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Sample records for respiratory gated multidetector

  1. Respiratory gating in cardiac PET

    DEFF Research Database (Denmark)

    Lassen, Martin Lyngby; Rasmussen, Thomas; Christensen, Thomas E

    2017-01-01

    BACKGROUND: Respiratory motion due to breathing during cardiac positron emission tomography (PET) results in spatial blurring and erroneous tracer quantification. Respiratory gating might represent a solution by dividing the PET coincidence dataset into smaller respiratory phase subsets. The aim...... of our study was to compare the resulting imaging quality by the use of a time-based respiratory gating system in two groups administered either adenosine or dipyridamole as the pharmacological stress agent. METHODS AND RESULTS: Forty-eight patients were randomized to adenosine or dipyridamole cardiac...... stress (82)RB-PET. Respiratory rates and depths were measured by a respiratory gating system in addition to registering actual respiratory rates. Patients undergoing adenosine stress showed a decrease in measured respiratory rate from initial to later scan phase measurements [12.4 (±5.7) vs 5.6 (±4...

  2. Evaluation of respiratory pattern during respiratory-gated radiotherapy

    International Nuclear Information System (INIS)

    Dobashi, Suguru; Mori, Shinichiro

    2014-01-01

    The respiratory cycle is not strictly regular, and generally varies in amplitude and period from one cycle to the next. We evaluated the characteristics of respiratory patterns acquired during respiratory gating treatment in more than 300 patients. A total 331 patients treated with respiratory-gated carbon-ion beam therapy were selected from a group of patients with thoracic and abdominal conditions. Respiratory data were acquired for a total of 3,171 fractions using an external respiratory sensing monitor and evaluated for respiratory cycle, duty cycle, magnitude of baseline drift, and intrafractional/interfractional peak inhalation/exhalation positional variation. Results for the treated anatomical sites and patient positioning were compared. Mean ± SD respiratory cycle averaged over all patients was 4.1 ± 1.3 s. Mean ± SD duty cycle averaged over all patients was 36.5 ± 7.3 %. Two types of baseline drift were seen, the first decremental and the second incremental. For respiratory peak variation, the mean intrafractional variation in peak-inhalation position relative to the amplitude in the first respiratory cycle (15.5 ± 9.3 %) was significantly larger than that in exhalation (7.5 ± 4.6 %). Interfractional variations in inhalation (17.2 ± 18.5 %) were also significantly greater than those in exhalation (9.4 ± 10.0 %). Statistically significant differences were observed between patients in the supine position and those in the prone position in mean respiratory cycle, duty cycle, and intra-/interfractional variations. We quantified the characteristics of the respiratory curve based on a large number of respiratory data obtained during treatment. These results might be useful in improving the accuracy of respiratory-gated treatment.

  3. Respiratory gating in positron emission tomography: A quantitative comparison of different gating schemes

    International Nuclear Information System (INIS)

    Dawood, Mohammad; Buether, Florian; Lang, Norbert; Schober, Otmar; Schaefers, Klaus P

    2007-01-01

    Respiratory gating is used for reducing the effects of breathing motion in a wide range of applications from radiotherapy treatment to diagnostical imaging. Different methods are feasible for respiratory gating. In this study seven gating methods were developed and tested on positron emission tomography (PET) listmode data. The results of seven patient studies were compared quantitatively with respect to motion and noise. (1) Equal and (2) variable time-based gating methods use only the time information of the breathing cycle to define respiratory gates. (3) Equal and (4) variable amplitude-based gating approaches utilize the amplitude of the respiratory signal. (5) Cycle-based amplitude gating is a combination of time and amplitude-based techniques. A baseline correction was applied to methods (3) and (4) resulting in two new approaches: Baseline corrected (6) equal and (7) variable amplitude-based gating. Listmode PET data from seven patients were acquired together with a respiratory signal. Images were reconstructed applying the seven gating methods. Two parameters were used to quantify the results: Motion was measured as the displacement of the heart due to respiration and noise was defined as the standard deviation of pixel intensities in a background region. The amplitude-based approaches (3) and (4) were superior to the time-based methods (1) and (2). The improvement in capturing the motion was more than 30% (up to 130%) in all subjects. The variable time (2) and amplitude (4) methods had a more uniform noise distribution among all respiratory gates compared to equal time (1) and amplitude (3) methods. Baseline correction did not improve the results. Out of seven different respiratory gating approaches, the variable amplitude method (4) captures the respiratory motion best while keeping a constant noise level among all respiratory phases

  4. Audio-visual biofeedback for respiratory-gated radiotherapy: Impact of audio instruction and audio-visual biofeedback on respiratory-gated radiotherapy

    International Nuclear Information System (INIS)

    George, Rohini; Chung, Theodore D.; Vedam, Sastry S.; Ramakrishnan, Viswanathan; Mohan, Radhe; Weiss, Elisabeth; Keall, Paul J.

    2006-01-01

    Purpose: Respiratory gating is a commercially available technology for reducing the deleterious effects of motion during imaging and treatment. The efficacy of gating is dependent on the reproducibility within and between respiratory cycles during imaging and treatment. The aim of this study was to determine whether audio-visual biofeedback can improve respiratory reproducibility by decreasing residual motion and therefore increasing the accuracy of gated radiotherapy. Methods and Materials: A total of 331 respiratory traces were collected from 24 lung cancer patients. The protocol consisted of five breathing training sessions spaced about a week apart. Within each session the patients initially breathed without any instruction (free breathing), with audio instructions and with audio-visual biofeedback. Residual motion was quantified by the standard deviation of the respiratory signal within the gating window. Results: Audio-visual biofeedback significantly reduced residual motion compared with free breathing and audio instruction. Displacement-based gating has lower residual motion than phase-based gating. Little reduction in residual motion was found for duty cycles less than 30%; for duty cycles above 50% there was a sharp increase in residual motion. Conclusions: The efficiency and reproducibility of gating can be improved by: incorporating audio-visual biofeedback, using a 30-50% duty cycle, gating during exhalation, and using displacement-based gating

  5. Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification

    Science.gov (United States)

    Wang, Shouyi; Bowen, Stephen R.; Chaovalitwongse, W. Art; Sandison, George A.; Grabowski, Thomas J.; Kinahan, Paul E.

    2014-02-01

    The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUVpeak) over lesions of interest. Relative differences in SUVpeak between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUVpeak values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion compensation

  6. Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification

    International Nuclear Information System (INIS)

    Wang, Shouyi; Chaovalitwongse, W Art; Bowen, Stephen R; Kinahan, Paul E; Sandison, George A; Grabowski, Thomas J

    2014-01-01

    The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUV peak ) over lesions of interest. Relative differences in SUV peak between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUV peak values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion

  7. Visualization of neonatal coronary arteries on multidetector row CT: ECG-gated versus non-ECG-gated technique

    International Nuclear Information System (INIS)

    Tsai, I.C.; Lee, Tain; Chen, Min-Chi; Fu, Yun-Ching; Jan, Sheng-Lin; Wang, Chung-Chi; Chang, Yen

    2007-01-01

    Multidetector CT (MDCT) seems to be a promising tool for detection of neonatal coronary arteries, but whether the ECG-gated or non-ECG-gated technique should be used has not been established. To compare the detection rate and image quality of neonatal coronary arteries on MDCT using ECG-gated and non-ECG-gated techniques. Twelve neonates with complex congenital heart disease were included. The CT scan was acquired using an ECG-gated technique, and the most quiescent phase of the RR interval was selected to represent the ECG-gated images. The raw data were then reconstructed without the ECG signal to obtain non-ECG-gated images. The detection rate and image quality of nine coronary artery segments in the two sets of images were then compared. A two-tailed paired t test was used with P values <0.05 considered as statistically significant. In all coronary segments the ECG-gated technique had a better detection rate and produced images of better quality. The difference between the two techniques ranged from 25% in the left main coronary artery to 100% in the distal right coronary artery. For neonates referred for MDCT, if evaluation of coronary artery anatomy is important for the clinical management or surgical planning, the ECG-gated technique should be used because it can reliably detect the coronary arteries. (orig.)

  8. The clinical implementation of respiratory-gated intensity-modulated radiotherapy

    International Nuclear Information System (INIS)

    Keall, Paul; Vedam, Sastry; George, Rohini; Bartee, Chris; Siebers, Jeffrey; Lerma, Fritz; Weiss, Elisabeth; Chung, Theodore

    2006-01-01

    The clinical use of respiratory-gated radiotherapy and the application of intensity-modulated radiotherapy (IMRT) are 2 relatively new innovations to the treatment of lung cancer. Respiratory gating can reduce the deleterious effects of intrafraction motion, and IMRT can concurrently increase tumor dose homogeneity and reduce dose to critical structures including the lungs, spinal cord, esophagus, and heart. The aim of this work is to describe the clinical implementation of respiratory-gated IMRT for the treatment of non-small cell lung cancer. Documented clinical procedures were developed to include a tumor motion study, gated CT imaging, IMRT treatment planning, and gated IMRT delivery. Treatment planning procedures for respiratory-gated IMRT including beam arrangements and dose-volume constraints were developed. Quality assurance procedures were designed to quantify both the dosimetric and positional accuracy of respiratory-gated IMRT, including film dosimetry dose measurements and Monte Carlo dose calculations for verification and validation of individual patient treatments. Respiratory-gated IMRT is accepted by both treatment staff and patients. The dosimetric and positional quality assurance test results indicate that respiratory-gated IMRT can be delivered accurately. If carefully implemented, respiratory-gated IMRT is a practical alternative to conventional thoracic radiotherapy. For mobile tumors, respiratory-gated radiotherapy is used as the standard of care at our institution. Due to the increased workload, the choice of IMRT is taken on a case-by-case basis, with approximately half of the non-small cell lung cancer patients receiving respiratory-gated IMRT. We are currently evaluating whether superior tumor coverage and limited normal tissue dosing will lead to improvements in local control and survival in non-small cell lung cancer

  9. Quality verification for respiratory gated proton therapy

    International Nuclear Information System (INIS)

    Kim, Eun Sook; Jang, Yo Jong; Park, Ji Yeon; Kang, Dong Yun; Yeom, Doo Seok

    2013-01-01

    To verify accuracy of respiratory gated proton therapy by measuring and analyzing proton beam delivered when respiratory gated proton therapy is being performed in our institute. The plan data of 3 patients who took respiratory gated proton therapy were used to deliver proton beam from proton therapy system. The manufactured moving phantom was used to apply respiratory gating system to reproduce proton beam which was partially irradiated. The key characteristics of proton beam, range, spreat-out Bragg peak (SOBP) and output factor were measured 5 times and the same categories were measured in the continuous proton beam which was not performed with respiratory gating system. Multi-layer ionization chamber was used to measure range and SOBP, and Scanditronix Wellhofer and farmer chamber was used to measure output factor. The average ranges of 3 patients (A, B, C), who had taken respiratory gated proton therapy or not, were (A) 7.226, 7.230, (B) 12.216, 12.220 and (C) 19.918, 19.920 g/cm 2 and average SOBP were (A) 4.950, 4.940, (B) 6.496, 6.512 and (C) 8.486, 8.490 g/cm 2 . And average output factor were (A) 0.985, 0.984 (B) 1.026, 1.027 and (C) 1.138, 1.136 cGy/MU. The differences of average range were -0.004, -0.004, -0.002 g/cm 2 , that of SOBP were 0.010, -0.016, -0.004 g/cm 2 and that of output factor were 0.001, -0.001, 0.002 cGy/MU. It is observed that the range, SOBP and output factor of proton beam delivered when respiratory gated proton therapy is being performed have the same beam quality with no significant difference compared to the proton beam which was continuously irradiated. Therefore, this study verified the quality of proton beam delivered when respiratory gated proton therapy and confirmed the accuracy of proton therapy using this

  10. Determination of prospective displacement-based gate threshold for respiratory-gated radiation delivery from retrospective phase-based gate threshold selected at 4D CT simulation

    International Nuclear Information System (INIS)

    Vedam, S.; Archambault, L.; Starkschall, G.; Mohan, R.; Beddar, S.

    2007-01-01

    Four-dimensional (4D) computed tomography (CT) imaging has found increasing importance in the localization of tumor and surrounding normal structures throughout the respiratory cycle. Based on such tumor motion information, it is possible to identify the appropriate phase interval for respiratory gated treatment planning and delivery. Such a gating phase interval is determined retrospectively based on tumor motion from internal tumor displacement. However, respiratory-gated treatment is delivered prospectively based on motion determined predominantly from an external monitor. Therefore, the simulation gate threshold determined from the retrospective phase interval selected for gating at 4D CT simulation may not correspond to the delivery gate threshold that is determined from the prospective external monitor displacement at treatment delivery. The purpose of the present work is to establish a relationship between the thresholds for respiratory gating determined at CT simulation and treatment delivery, respectively. One hundred fifty external respiratory motion traces, from 90 patients, with and without audio-visual biofeedback, are analyzed. Two respiratory phase intervals, 40%-60% and 30%-70%, are chosen for respiratory gating from the 4D CT-derived tumor motion trajectory. From residual tumor displacements within each such gating phase interval, a simulation gate threshold is defined based on (a) the average and (b) the maximum respiratory displacement within the phase interval. The duty cycle for prospective gated delivery is estimated from the proportion of external monitor displacement data points within both the selected phase interval and the simulation gate threshold. The delivery gate threshold is then determined iteratively to match the above determined duty cycle. The magnitude of the difference between such gate thresholds determined at simulation and treatment delivery is quantified in each case. Phantom motion tests yielded coincidence of simulation

  11. Respiratory gated lung CT using 320-row area detector CT

    International Nuclear Information System (INIS)

    Sakamoto, Ryo; Noma, Satoshi; Higashino, Takanori

    2010-01-01

    Three hundred and twenty-row Area Detector CT (ADCT) has made it possible to scan whole lung field with prospective respiratory gated wide volume scan. We evaluated whether the respiratory gated wide volume scan enables to reduce motion induced artifacts in the lung area. Helical scan and respiratory gated wide volume scan were performed in 5 patients and 10 healthy volunteers under spontaneous breathing. Significant reduction of motion artifact and superior image quality were obtained in respiratory gated scan in comparison with helical scan. Respiratory gated wide volume scan is an unique method using ADCT, and is able to reduce motion artifacts in lung CT scans of patients unable to suspend respiration in clinical scenes. (author)

  12. Respiratory gated beam delivery cannot facilitate margin reduction, unless combined with respiratory correlated image guidance

    International Nuclear Information System (INIS)

    Korreman, Stine S.; Juhler-Nottrup, Trine; Boyer, Arthur L.

    2008-01-01

    Purpose/objective: In radiotherapy of targets moving with respiration, beam gating is offered as a means of reducing the target motion. The purpose of this study is to evaluate the safe magnitude of margin reduction for respiratory gated beam delivery. Materials/methods: The study is based on data for 17 lung cancer patients in separate protocols at Rigshospitalet and Stanford Cancer Center. Respiratory curves for external optical markers and implanted fiducials were collected using equipment based on the RPM system (Varian Medical Systems). A total of 861 respiratory curves represented external measurements over 30 fraction treatment courses for 10 patients, and synchronous external/internal measurements in single sessions for seven patients. Variations in respiratory amplitude (simulated coaching) and external/internal phase shifts were simulated by perturbation with realistic values. Variations were described by medians and standard deviations (SDs) of position distributions of the markers. Gating windows (35% duty cycle) were retrospectively applied to the respiratory data for each session, mimicking the use of commercially available gating systems. Medians and SDs of gated data were compared to those of ungated data, to assess potential margin reductions. Results: External respiratory data collected over entire treatment courses showed SDs from 1.6 to 8.1 mm, the major part arising from baseline variations. The gated data had SDs from 1.5 to 7.7 mm, with a mean reduction of 0.3 mm (6%). Gated distributions were more skewed than ungated, and in a few cases a marginal miss of gated respiration would be found even if no margin reduction was applied. Regularization of breathing amplitude to simulate coaching did not alter these results significantly. Simulation of varying phase shifts between internal and external respiratory signals showed that the SDs of gated distributions were the same as for the ungated or smaller, but the median values were markedly shifted

  13. Respiratory signal analysis of liver cancer patients with respiratory-gated radiation therapy

    International Nuclear Information System (INIS)

    Kang, Dong Im; Jung, Sang Hoon; Kim, Chul Jong; Park, Hee Chul; Choi, Byung Ki

    2015-01-01

    External markers respiratory movement measuring device (RPM; Real-time Position Management, Varian Medical System, USA) Liver Cancer Radiation Therapy Respiratory gated with respiratory signal with irradiation time and the actual research by analyzing the respiratory phase with the breathing motion measurement device respiratory tuning evaluate the accuracy of radiation therapy May-September 2014 Novalis Tx. (Varian Medical System, USA) and liver cancer radiotherapy using respiratory gated RPM (Duty Cycle 20%, Gating window 40%-60%) of 16 patients who underwent total when recording the analyzed respiratory movement. After the breathing motion of the external markers recorded on the RPM was reconstructed by breathing through the acts phase analysis, for Beam-on Time and Duty Cycle recorded by using the reconstructed phase breathing breathing with RPM gated the prediction accuracy of the radiation treatment analysis and analyzed the correlation between prediction accuracy and Duty Cycle in accordance with the reproducibility of the respiratory movement. Treatment of 16 patients with respiratory cycle during the actual treatment plan was analyzed with an average difference -0.03 seconds (range -0.50 seconds to 0.09 seconds) could not be confirmed statistically significant difference between the two breathing (p = 0.472). The average respiratory period when treatment is 4.02 sec (0.71 sec), the average value of the respiratory cycle of the treatment was characterized by a standard deviation 7.43% (range 2.57 to 19.20%). Duty Cycle is that the actual average 16.05% (range 13.78 to 17.41%), average 56.05 got through the acts of the show and then analyzed% (range 39.23 to 75.10%) is planned in respiratory research phase (40% to 60%) in was confirmed. The investigation on the correlation between the ratio Duty Cycle and planned respiratory phase and the standard deviation of the respiratory cycle was analyzed in each -0.156 (p = 0.282) and -0.385 (p = 0.070). This study is

  14. Efficiency of respiratory-gated delivery of synchrotron-based pulsed proton irradiation

    International Nuclear Information System (INIS)

    Tsunashima, Yoshikazu; Vedam, Sastry; Dong, Lei; Bues, Martin; Balter, Peter; Smith, Alfred; Mohan, Radhe; Umezawa, Masumi; Sakae, Takeji

    2008-01-01

    Significant differences exist in respiratory-gated proton beam delivery with a synchrotron-based accelerator system when compared to photon therapy with a conventional linear accelerator. Delivery of protons with a synchrotron accelerator is governed by a magnet excitation cycle pattern. Optimal synchronization of the magnet excitation cycle pattern with the respiratory motion pattern is critical to the efficiency of respiratory-gated proton delivery. There has been little systematic analysis to optimize the accelerator's operational parameters to improve gated treatment efficiency. The goal of this study was to estimate the overall efficiency of respiratory-gated synchrotron-based proton irradiation through realistic simulation. Using 62 respiratory motion traces from 38 patients, we simulated respiratory gating for duty cycles of 30%, 20% and 10% around peak exhalation for various fixed and variable magnet excitation patterns. In each case, the time required to deliver 100 monitor units in both non-gated and gated irradiation scenarios was determined. Based on results from this study, the minimum time required to deliver 100 MU was 1.1 min for non-gated irradiation. For respiratory-gated delivery at a 30% duty cycle around peak exhalation, corresponding average delivery times were typically three times longer with a fixed magnet excitation cycle pattern. However, when a variable excitation cycle was allowed in synchrony with the patient's respiratory cycle, the treatment time only doubled. Thus, respiratory-gated delivery of synchrotron-based pulsed proton irradiation is feasible and more efficient when a variable magnet excitation cycle pattern is used

  15. Retrospectively ECG-gated multi-detector row CT of the chest: does ECG-gating improve three-dimensional visualization of the bronchial tree?

    International Nuclear Information System (INIS)

    Schertler, T.; Wildermuth, S.; Willmann, J.K.; Crook, D.W.; Marincek, B.; Boehm, T.

    2004-01-01

    Purpose: To determine the impact of retrospectively ECG-gated multi-detector row CT (MDCT) on three-dimensional (3D) visualization of the bronchial tree and virtual bronchoscopy (VB) as compared to non-ECG-gated data acquisition. Materials and Methods: Contrast-enhanced retrospectively ECG-gated and non-ECG-gated MDCT of the chest was performed in 25 consecutive patients referred for assessment of coronary artery bypass grafts and pathology of the ascending aorta. ECG-gated MDCT data were reconstructed in diastole using an absolute reverse delay of -400 msec in all patients. In 10 patients additional reconstructions at -200 msec, -300 msec, and -500 msec prior to the R-wave were performed. Shaded surface display (SSD) and virtual bronchoscopy (VB) for visualization of the bronchial segments was performed with ECG-gated and non-ECG-gated MDCT data. The visualization of the bronchial tree underwent blinded scoring. Effective radiation dose and signal-to-noise ratio (SNR) for both techniques were compared. Results: There was no significant difference in visualizing single bronchial segments using ECG-gated compared to non-ECG-gated MDCT data. However, the total sum of scores for all bronchial segments visualized with non-ECG-gated MDCT was significantly higher compared to ECG-gated MDCT (P [de

  16. Intrinsic respiratory gating in small-animal CT

    International Nuclear Information System (INIS)

    Bartling, Soenke H.; Dinkel, Julien; Kauczor, Hans-Ulrich; Stiller, Wolfram; Semmler, Wolfhard; Grasruck, Michael; Madisch, Ijad; Gupta, Rajiv; Kiessling, Fabian

    2008-01-01

    Gating in small-animal CT imaging can compensate artefacts caused by physiological motion during scanning. However, all published gating approaches for small animals rely on additional hardware to derive the gating signals. In contrast, in this study a novel method of intrinsic respiratory gating of rodents was developed and tested for mice (n=5), rats (n=5) and rabbits (n=2) in a flat-panel cone-beam CT system. In a consensus read image quality was compared with that of non-gated and retrospective extrinsically gated scans performed using a pneumatic cushion. In comparison to non-gated images, image quality improved significantly using intrinsic and extrinsic gating. Delineation of diaphragm and lung structure improved in all animals. Image quality of intrinsically gated CT was judged to be equivalent to extrinsically gated ones. Additionally 4D datasets were calculated using both gating methods. Values for expiratory, inspiratory and tidal lung volumes determined with the two gating methods were comparable and correlated well with values known from the literature. We could show that intrinsic respiratory gating in rodents makes additional gating hardware and preparatory efforts superfluous. This method improves image quality and allows derivation of functional data. Therefore it bears the potential to find wide applications in small-animal CT imaging. (orig.)

  17. Retrospective data-driven respiratory gating for PET/CT

    International Nuclear Information System (INIS)

    Schleyer, Paul J; O'Doherty, Michael J; Barrington, Sally F; Marsden, Paul K

    2009-01-01

    Respiratory motion can adversely affect both PET and CT acquisitions. Respiratory gating allows an acquisition to be divided into a series of motion-reduced bins according to the respiratory signal, which is typically hardware acquired. In order that the effects of motion can potentially be corrected for, we have developed a novel, automatic, data-driven gating method which retrospectively derives the respiratory signal from the acquired PET and CT data. PET data are acquired in listmode and analysed in sinogram space, and CT data are acquired in cine mode and analysed in image space. Spectral analysis is used to identify regions within the CT and PET data which are subject to respiratory motion, and the variation of counts within these regions is used to estimate the respiratory signal. Amplitude binning is then used to create motion-reduced PET and CT frames. The method was demonstrated with four patient datasets acquired on a 4-slice PET/CT system. To assess the accuracy of the data-derived respiratory signal, a hardware-based signal was acquired for comparison. Data-driven gating was successfully performed on PET and CT datasets for all four patients. Gated images demonstrated respiratory motion throughout the bin sequences for all PET and CT series, and image analysis and direct comparison of the traces derived from the data-driven method with the hardware-acquired traces indicated accurate recovery of the respiratory signal.

  18. Prospective respiratory-gated micro-CT of free breathing rodents

    International Nuclear Information System (INIS)

    Ford, Nancy L.; Nikolov, Hristo N.; Norley, Chris J.D.; Thornton, Michael M.; Foster, Paula J.; Drangova, Maria; Holdsworth, David W.

    2005-01-01

    Microcomputed tomography (Micro-CT) has the potential to noninvasively image the structure of organs in rodent models with high spatial resolution and relatively short image acquisition times. However, motion artifacts associated with the normal respiratory motion of the animal may arise when imaging the abdomen or thorax. To reduce these artifacts and the accompanying loss of spatial resolution, we propose a prospective respiratory gating technique for use with anaesthetized, free-breathing rodents. A custom-made bed with an embedded pressure chamber was connected to a pressure transducer. Anaesthetized animals were placed in the prone position on the bed with their abdomens located over the chamber. During inspiration, the motion of the diaphragm caused an increase in the chamber pressure, which was converted into a voltage signal by the transducer. An output voltage was used to trigger image acquisition at any desired time point in the respiratory cycle. Digital radiographic images were acquired of anaesthetized, free-breathing rats with a digital radiographic system to correlate the respiratory wave form with respiration-induced organ motion. The respiratory wave form was monitored and recorded simultaneously with the x-ray radiation pulses, and an imaging window was defined, beginning at end expiration. Phantom experiments were performed to verify that the respiratory gating apparatus was triggering the micro-CT system. Attached to the distensible phantom were 100 μm diameter copper wires and the measured full width at half maximum was used to assess differences in image quality between respiratory-gated and ungated imaging protocols. This experiment allowed us to quantify the improvement in the spatial resolution, and the reduction of motion artifacts caused by moving structures, in the images resulting from respiratory-gated image acquisitions. The measured wire diameters were 0.135 mm for the stationary phantom image, 0.137 mm for the image gated at end

  19. Role of respiratory-gated PET/CT for pancreatic tumors: A preliminary result

    International Nuclear Information System (INIS)

    Kasuya, Takeo; Tateishi, Ukihide; Suzuki, Kazufumi; Daisaki, Hiromitsu; Nishiyama, Yuji; Hata, Masaharu; Inoue, Tomio

    2013-01-01

    Purpose: The aim of this study is to ascertain role of respiratory-gated PET/CT for accurate diagnosis of pancreatic tumors. Materials and methods: Prior to clinical study, the phantom study was performed to evaluate the impact of respiratory motion on lesion quantification. Twenty-two patients (mean age 65 years) with pancreatic tumors were enrolled. Pathological diagnoses by surgical specimens consisted of pancreatic cancer (n = 15) and benign intraductal papillary mucinous neoplasm (IPMN, n = 7). Whole-body scan of non-respiratory-gated PET/CT was performed at first, and subsequent respiratory-gated PET/CT for one bed position was performed. All PET/CT studies were performed prior to surgery. The SUV max obtained by non-respiratory-gated PET/CT and respiratory-gated PET/CT, and percent difference in SUVmax (%SUVmax) were compared. Results: The profile curve of 5 respiratory bin image was most similar to that of static image. The third bin of 5 respiratory bin image showed highest FWHM (24.0 mm) and FWTM (32.7 mm). The mean SUVmax of pancreatic cancer was similar to that of benign IPMN on non-respiratory-gated PET/CT (p = 0.05), whereas significant difference was found between two groups on respiratory-gated PET/CT (p = 0.016). The mean %SUV of pancreatic cancer was greater than that of benign IPMN (p < 0.0001). Identification of the primary tumor in pancreatic head (n = 13, 59%) was improved by using respiratory-gated PET/CT because of minimal affection of physiological accumulation in duodenum. Conclusion: Respiratory-gated PET/CT is a feasible technique for evaluation of pancreatic tumors and allows more accurate identification of pancreatic tumors compared with non-respiratory-gated PET/CT

  20. Integrated cardio-thoracic imaging with ECG-Gated 64-slice multidetector-row CT: initial findings in 133 patients

    International Nuclear Information System (INIS)

    Salem, Randa; Remy-Jardin, Martine; Delhaye, Damien; Khalil, Chadi; Teisseire, Antoine; Remy, Jacques; Delannoy-Deken, Valerie; Duhamel, Alain

    2006-01-01

    The purpose of this study was to investigate the possibility of assessing the underlying respiratory disease as well as cardiac function during ECG-gated CT angiography of the chest with 64-slice multidetector-row CT (MDCT). One hundred thirty-three consecutive patients in sinus rhythm with known or suspected ventricular dysfunction underwent an ECG-gated CT angiographic examination of the chest without β-blockers using the following parameters: (1) collimation: 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices (Sensation 64; Siemens); rotation time: 0.33 s; pitch: 0.3; 120 kV; 200 mAs; ECG-controlled dose modulation (ECG-pulsing) and (2) 120 ml of a 35% contrast agent. Data were reconstructed: (1) to evaluate the underlying respiratory disease (1-mm thick lung and mediastinal scans reconstructed at 55% of the R-R interval; i.e., ''morphologic scans'') and (2) to determine right (RVEF) and left (LVEF) ventricular ejection fractions (short-axis systolic and diastolic images; Argus software; i.e., ''functional scans''). The mean heart rate was 73 bpm (range: 42-120) and the mean scan time was 18.11±2.67 s (range: 10-27). A total of 123 examinations (92%) had both lung and mediastinal images rated as diagnostic scans, whereas 10 examinations (8%) had non-diagnostic images altered by the presence of respiratory-motion artifacts (n=4) or cyclic artifacts related to the use of a pitch value of 0.3 in patients with a very low heart rate during data acquisition (n=6). Assessment of right and left ventricular function was achievable in 124 patients (93%, 95% CI: 88-97%). For these 124 examinations, the mean RVEF was 46.10% (±9.5; range: 20-72) and the mean LVEF was 58.23% (±10.88; range: 20-83). In the remaining nine patients, an imprecise segmentation of the right and left ventricular cavities was considered as a limiting factor for precise calculation of end-systolic and end-diastolic ventricular volumes. The mean (±SD) DLP

  1. Dose profile measurements during respiratory-gated lung stereotactic radiotherapy: A phantom study

    International Nuclear Information System (INIS)

    Jong, W L; Ung, N M; Wong, J H D; Ng, K H

    2016-01-01

    During stereotactic body radiotherapy, high radiation dose (∼60 Gy) is delivered to the tumour in small fractionation regime. In this study, the dosimetric characteristics were studied using radiochromic film during respiratory-gated and non-gated lung stereotactic body radiotherapy (SBRT). Specifically, the effect of respiratory cycle and amplitude, as well as gating window on the dosimetry were studied. In this study, the dose profiles along the irradiated area were measured. The dose profiles for respiratory-gated radiation delivery with different respiratory or tumour motion amplitudes, gating windows and respiratory time per cycle were in agreement with static radiation delivery. The respiratory gating system was able to deliver the radiation dose accurately (±1.05 mm) in the longitudinal direction. Although the treatment time for respiratory-gated SBRT was prolonged, this approach can potentially reduce the margin for internal tumour volume without compromising the tumour coverage. In addition, the normal tissue sparing effect can be improved. (paper)

  2. Accuracy and Consistency of Respiratory Gating in Abdominal Cancer Patients

    International Nuclear Information System (INIS)

    Ge, Jiajia; Santanam, Lakshmi; Yang, Deshan; Parikh, Parag J.

    2013-01-01

    Purpose: To evaluate respiratory gating accuracy and intrafractional consistency for abdominal cancer patients treated with respiratory gated treatment on a regular linear accelerator system. Methods and Materials: Twelve abdominal patients implanted with fiducials were treated with amplitude-based respiratory-gated radiation therapy. On the basis of daily orthogonal fluoroscopy, the operator readjusted the couch position and gating window such that the fiducial was within a setup margin (fiducial-planning target volume [f-PTV]) when RPM indicated “beam-ON.” Fifty-five pre- and post-treatment fluoroscopic movie pairs with synchronized respiratory gating signal were recorded. Fiducial motion traces were extracted from the fluoroscopic movies using a template matching algorithm and correlated with f-PTV by registering the digitally reconstructed radiographs with the fluoroscopic movies. Treatment was determined to be “accurate” if 50% of the fiducial area stayed within f-PTV while beam-ON. For movie pairs that lost gating accuracy, a MATLAB program was used to assess whether the gating window was optimized, the external-internal correlation (EIC) changed, or the patient moved between movies. A series of safety margins from 0.5 mm to 3 mm was added to f-PTV for reassessing gating accuracy. Results: A decrease in gating accuracy was observed in 44% of movie pairs from daily fluoroscopic movies of 12 abdominal patients. Three main causes for inaccurate gating were identified as change of global EIC over time (∼43%), suboptimal gating setup (∼37%), and imperfect EIC within movie (∼13%). Conclusions: Inconsistent respiratory gating accuracy may occur within 1 treatment session even with a daily adjusted gating window. To improve or maintain gating accuracy during treatment, we suggest using at least a 2.5-mm safety margin to account for gating and setup uncertainties

  3. Patient training in respiratory-gated radiotherapy

    International Nuclear Information System (INIS)

    Kini, Vijay R.; Vedam, Subrahmanya S.; Keall, Paul J.; Patil, Sumukh; Chen, Clayton; Mohan, Radhe

    2003-01-01

    Respiratory gating is used to counter the effects of organ motion during radiotherapy for chest tumors. The effects of variations in patient breathing patterns during a single treatment and from day to day are unknown. We evaluated the feasibility of using patient training tools and their effect on the breathing cycle regularity and reproducibility during respiratory-gated radiotherapy. To monitor respiratory patterns, we used a component of a commercially available respiratory-gated radiotherapy system (Real Time Position Management (RPM) System, Varian Oncology Systems, Palo Alto, CA 94304). This passive marker video tracking system consists of reflective markers placed on the patient's chest or abdomen, which are detected by a wall-mounted video camera. Software installed on a PC interfaced to this camera detects the marker motion digitally and records it. The marker position as a function of time serves as the motion signal that may be used to trigger imaging or treatment. The training tools used were audio prompting and visual feedback, with free breathing as a control. The audio prompting method used instructions to 'breathe in' or 'breathe out' at periodic intervals deduced from patients' own breathing patterns. In the visual feedback method, patients were shown a real-time trace of their abdominal wall motion due to breathing. Using this, they were asked to maintain a constant amplitude of motion. Motion traces of the abdominal wall were recorded for each patient for various maneuvers. Free breathing showed a variable amplitude and frequency. Audio prompting resulted in a reproducible frequency; however, the variability and the magnitude of amplitude increased. Visual feedback gave a better control over the amplitude but showed minor variations in frequency. We concluded that training improves the reproducibility of amplitude and frequency of patient breathing cycles. This may increase the accuracy of respiratory-gated radiation therapy

  4. Respiratory gating of cardiac PET data in list-mode acquisition

    International Nuclear Information System (INIS)

    Livieratos, Lefteris; Rajappan, Kim; Camici, Paolo G.; Stegger, Lars; Schafers, Klaus; Bailey, Dale L.

    2006-01-01

    Respiratory motion has been identified as a source of artefacts in most medical imaging modalities. This paper reports on respiratory gating as a means to eliminate motion-related inaccuracies in PET imaging. Respiratory gating was implemented in list mode with physiological signal recorded every millisecond together with the PET data. Respiration was monitored with an inductive respiration monitor using an elasticised belt around the patient's chest. Simultaneous ECG gating can be maintained independently by encoding ECG trigger signal into the list-mode data. Respiratory gating is performed in an off-line workstation with gating parameters defined retrospectively. The technique was applied on a preliminary set of patient data with C 15 O. Motion was visually observed in the cine displays of the sagittal and coronal views of the reconstructed respiratory gated images. Significant changes in the cranial-caudal position of the heart could be observed. The centroid of the cardiac blood pool showed an excursion of 4.5-16.5 mm (mean 8.5±4.8 mm) in the cranial-caudal direction, with more limited excursion of 1.1-7.0 mm (mean 2.5±2.2 mm) in the horizontal direction and 1.3-3.7 mm (mean 2.4±0.9 mm) in the vertical direction. These preliminary data show that the extent of motion involved in respiration is comparable to myocardial wall thickness, and respiratory gating may be considered in order to reduce this effect in the reconstructed images. (orig.)

  5. Respiratory gating of cardiac PET data in list-mode acquisition.

    Science.gov (United States)

    Livieratos, Lefteris; Rajappan, Kim; Stegger, Lars; Schafers, Klaus; Bailey, Dale L; Camici, Paolo G

    2006-05-01

    Respiratory motion has been identified as a source of artefacts in most medical imaging modalities. This paper reports on respiratory gating as a means to eliminate motion-related inaccuracies in PET imaging. Respiratory gating was implemented in list mode with physiological signal recorded every millisecond together with the PET data. Respiration was monitored with an inductive respiration monitor using an elasticised belt around the patient's chest. Simultaneous ECG gating can be maintained independently by encoding ECG trigger signal into the list-mode data. Respiratory gating is performed in an off-line workstation with gating parameters defined retrospectively. The technique was applied on a preliminary set of patient data with C(15)O. Motion was visually observed in the cine displays of the sagittal and coronal views of the reconstructed respiratory gated images. Significant changes in the cranial-caudal position of the heart could be observed. The centroid of the cardiac blood pool showed an excursion of 4.5-16.5 mm (mean 8.5+/-4.8 mm) in the cranial-caudal direction, with more limited excursion of 1.1-7.0 mm (mean 2.5+/-2.2 mm) in the horizontal direction and 1.3-3.7 mm (mean 2.4+/-0.9 mm) in the vertical direction. These preliminary data show that the extent of motion involved in respiration is comparable to myocardial wall thickness, and respiratory gating may be considered in order to reduce this effect in the reconstructed images.

  6. Respiratory gated radiotherapy: current techniques and potential benefits

    International Nuclear Information System (INIS)

    Giraud, P.; Campana, F.; Rosenwald, J.C.; Cosset, J.M.; Reboul, F.; Garcia, R.; Clippe, S.; Carrie, C.; Dubray, B.

    2003-01-01

    Respiration-gated radiotherapy offers a significant potential for improvement in the irradiation of tumor sites affected by respiratory motion such as lung, breast and liver tumors. An increased conformality of irradiation fields leading to decreased complications rates of organs at risk (lung, heart...) is expected. Respiratory gating is in line with the need for improved precision required by radiotherapy techniques such as 3D conformal radiotherapy or intensity modulated radiotherapy. Reduction of respiratory motion can be achieved by using either breath hold techniques or respiration synchronized gating techniques. Breath-hold techniques can be achieved with active, in which airflow of the patient is temporarily blocked by a valve, or passive techniques, in which the patient voluntarily breath-hold. Synchronized gating techniques use external devices to predict the phase of the respiration cycle while the patient breaths freely. These techniques presently investigated in several medical centers worldwide. Although promising, the first results obtained in lung and liver cancer patients require confirmation. Physical, technical and physiological questions still remain to be answered. This paper describes the most frequently used gated techniques and the main published clinical reports on the use of respiration-gated radiotherapy in order to evaluate the impact of these techniques. (author)

  7. Respiratory gating and multi field technique radiotherapy for esophageal cancer

    International Nuclear Information System (INIS)

    Ohta, Atsushi; Kaidu, Motoki; Tanabe, Satoshi

    2017-01-01

    To investigate the effects of a respiratory gating and multi field technique on the dose-volume histogram (DVH) in radiotherapy for esophageal cancer. Twenty patients who underwent four-dimensional computed tomography for esophageal cancer were included. We retrospectively created the four treatment plans for each patient, with or without the respiratory gating and multi field technique: No gating-2-field, No gating-4-field, Gating-2-field, and Gating-4-field plans. We compared the DVH parameters of the lung and heart in the No gating-2-field plan with the other three plans.Result In the comparison of the parameters in the No gating-2-field plan, there are significant differences in the Lung V 5Gy , V 20Gy , mean dose with all three plans and the Heart V 25Gy -V 40Gy with Gating-2-field plan, V 35Gy , V 40Gy , mean dose with No Gating-4-field plan and V 30Gy -V 40Gy , and mean dose with Gating-4-field plan. The lung parameters were smaller in the Gating-2-field plan and larger in the No gating-4-field and Gating-4-field plans. The heart parameters were all larger in the No gating-2-field plan. The lung parameters were reduced by the respiratory gating technique and increased by the multi field technique. The heart parameters were reduced by both techniques. It is important to select the optimal technique according to the risk of complications. (author)

  8. Cardiac pathologies incidentally detected with non-gated chest CT; Inzidentelle Pathologien des Herzens im Thorax-CT

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, Axel; Kroepil, P.; Lanzman, R.S.; Moedder, U. [Inst. fuer Radiologie, Universitaetsklinikum Duesseldorf, Heinrich-Heine-Univ. (Germany); Choy, G.; Abbara, S. [Cardiovascular Imaging Section, Massachusetts General Hospital, Harvard Medical School (United States)

    2009-12-15

    Cardiac imaging using electrocardiogram-gated multi-detector computed tomography (MDCT) permits noninvasive diagnosis of congenital and acquired cardiac pathologies and has thus become increasingly important in the last years. Several studies investigated the incidence and relevance of incidental extracardiac structures within the lungs, mediastinum, chest wall, and abdomen with gated coronary CT. This resulted in the general acceptance of the review of extracardiac structures as a routine component of coronary CT interpretation. On the other hand radiologists tend to neglect pericardial and cardiac pathologies in non-gated chest CT, which is primarily performed for the evaluation of the respiratory system or for tumor staging. Since the introduction of multi-detector spiral CT technology, the incidental detection of cardiac and pericardial findings has become possible using non-gated chest CT. This article reviews the imaging appearances and differential diagnostic considerations of incidental cardiac entities that may be encountered in non-gated chest CT. (orig.)

  9. Dose verification for respiratory-gated volumetric modulated arc therapy

    Energy Technology Data Exchange (ETDEWEB)

    Qian Jianguo; Xing Lei; Liu Wu; Luxton, Gary, E-mail: gluxton@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)

    2011-08-07

    A novel commercial medical linac system (TrueBeam(TM), Varian Medical Systems, Palo Alto, CA) allows respiratory-gated volumetric modulated arc therapy (VMAT), a new modality for treating moving tumors with high precision and improved accuracy by allowing for regular motion associated with a patient's breathing during VMAT delivery. The purpose of this work is to adapt a previously-developed dose reconstruction technique to evaluate the fidelity of VMAT treatment during gated delivery under clinic-relevant periodic motion related to patient breathing. A Varian TrueBeam system was used in this study. VMAT plans were created for three patients with lung or pancreas tumors. Conventional 6 and 15 MV beams with flattening filter and high-dose-rate 10 MV beams with no flattening filter were used in these plans. Each patient plan was delivered to a phantom first without gating and then with gating for three simulated respiratory periods (3, 4.5 and 6 s). Using the adapted log-file-based dose reconstruction procedure supplemented with ion chamber array (Seven29(TM), PTW, Freiburg, Germany) measurements, the delivered dose was used to evaluate the fidelity of gated VMAT delivery. Comparison of Seven29 measurements with and without gating showed good agreement with gamma-index passing rates above 99% for 1%/1 mm dose accuracy/distance-to-agreement criteria. With original plans as reference, gamma-index passing rates were 100% for the reconstituted plans (1%/1 mm criteria) and 93.5-100% for gated Seven29 measurements (3%/3 mm criteria). In the presence of leaf error deliberately introduced into the gated delivery of a pancreas patient plan, both dose reconstruction and Seven29 measurement consistently indicated substantial dosimetric differences from the original plan. In summary, a dose reconstruction procedure was demonstrated for evaluating the accuracy of respiratory-gated VMAT delivery. This technique showed that under clinical operation, the TrueBeam system

  10. Respiratory guiding system for respiratory motion management in respiratory gated radiotherapy

    International Nuclear Information System (INIS)

    Kang, Seong Hee; Kim, Dong Su; Kim, Tae Ho; Suh, Tae Suk

    2013-01-01

    Respiratory guiding systems have been shown to improve the respiratory regularity. This, in turn, improves the efficiency of synchronized moving aperture radiation therapy, and it reduces the artifacts caused by irregular breathing in imaging techniques such as four-dimensional computed tomography (4D CT), which is used for treatment planning in RGRT. We have previously developed a respiratory guiding system that incorporates an individual-specific guiding waveform, which is easy to follow for each volunteer, to improve the respiratory regularity. The present study evaluates the application of this system to improve the respiratory regularity for respiratory-gated radiation therapy (RGRT). In this study, we evaluated the effectiveness of an in-house-developed respiratory guiding system incorporating an individual specific guiding waveform to improve the respiratory regularity for RGRT. Most volunteers showed significantly less residual motion at each phase during guided breathing owing to the improvement in respiratory regularity. Therefore, the respiratory guiding system can clearly reduce the residual, or respiratory, motion in each phase. From the result, the CTV and the PTV margins during RGRT can be reduced by using the respiratory guiding system, which reduces the residual motions, thus improving the accuracy of RGRT

  11. Respiratory and cardiac motion correction in dual gated PET/MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fayad, Hadi; Monnier, Florian [LaTIM, INSERM, UMR 1101, Brest (France); Odille, Freedy; Felblinger, Jacques [INSERM U947, University of Nancy, Nancy (France); Lamare, Frederic [INCIA, UMR5287, CNRS, CHU Bordeaux, Bordeaux (France); Visvikis, Dimitris [LaTIM, INSERM, UMR 1101, Brest (France)

    2015-05-18

    Respiratory and cardiac motion in PET/MR imaging leads to reduced quantitative and qualitative image accuracy. Correction methodologies involve the use of double gated acquisitions which lead to low signal-to-noise ratio (SNR) and to issues concerning the combination of cardiac and respiratory frames. The objective of this work is to use a generalized reconstruction by inversion of coupled systems (GRICS) approach, previously used for PET/MR respiratory motion correction, combined with a cardiac phase signal and a reconstruction incorporated PET motion correction approach in order to reconstruct motion free images from dual gated PET acquisitions. The GRICS method consists of formulating parallel MRI in the presence of patient motion as a coupled inverse problem. Its resolution, using a fixed-point method, allows the reconstructed image to be improved using a motion model constructed from the raw MR data and two respiratory belts. GRICS obtained respiratory displacements are interpolated using the cardiac phase derived from an ECG to model simultaneous cardiac and respiratory motion. Three different volunteer datasets (4DMR acquisitions) were used for evaluation. GATE was used to simulate 4DPET datasets corresponding to the acquired 4DMR images. Simulated data were subsequently binned using 16 cardiac phases (M1) vs diastole only (M2), in combination with 8 respiratory amplitude gates. Respiratory and cardiac motion corrected PET images using either M1 or M2 were compared to respiratory only corrected images and evaluated in terms of SNR and contrast improvement. Significant visual improvements were obtained when correcting simultaneously for respiratory and cardiac motion (using 16 cardiac phase or diastole only) compared to respiratory motion only compensation. Results were confirmed by an associated increased SNR and contrast. Results indicate that using GRICS is an efficient tool for respiratory and cardiac motion correction in dual gated PET/MR imaging.

  12. Acquisition and automated 3-D segmentation of respiratory/cardiac-gated PET transmission images

    International Nuclear Information System (INIS)

    Reutter, B.W.; Klein, G.J.; Brennan, K.M.; Huesman, R.H.

    1996-01-01

    To evaluate the impact of respiratory motion on attenuation correction of cardiac PET data, we acquired and automatically segmented gated transmission data for a dog breathing on its own under gas anesthesia. Data were acquired for 20 min on a CTI/Siemens ECAT EXACT HR (47-slice) scanner configured for 12 gates in a static study, Two respiratory gates were obtained using data from a pneumatic bellows placed around the dog's chest, in conjunction with 6 cardiac gates from standard EKG gating. Both signals were directed to a LabVIEW-controlled Macintosh, which translated them into one of 12 gate addresses. The respiratory gating threshold was placed near end-expiration to acquire 6 cardiac-gated datasets at end-expiration and 6 cardiac-gated datasets during breaths. Breaths occurred about once every 10 sec and lasted about 1-1.5 sec. For each respiratory gate, data were summed over cardiac gates and torso and lung surfaces were segmented automatically using a differential 3-D edge detection algorithm. Three-dimensional visualizations showed that lung surfaces adjacent to the heart translated 9 mm inferiorly during breaths. Our results suggest that respiration-compensated attenuation correction is feasible with a modest amount of gated transmission data and is necessary for accurate quantitation of high-resolution gated cardiac PET data

  13. An integrated bioimpedance—ECG gating technique for respiratory and cardiac motion compensation in cardiac PET

    International Nuclear Information System (INIS)

    Koivumäki, Tuomas; Nekolla, Stephan G; Fürst, Sebastian; Loher, Simone; Schwaiger, Markus; Vauhkonen, Marko; Hakulinen, Mikko A

    2014-01-01

    Respiratory motion may degrade image quality in cardiac PET imaging. Since cardiac PET studies often involve cardiac gating by ECG, a separate respiratory monitoring system is required increasing the logistic complexity of the examination, in case respiratory gating is also needed. Thus, we investigated the simultaneous acquisition of both respiratory and cardiac gating signals using II limb lead mimicking electrode configuration during cardiac PET scans of 11 patients. In addition to conventional static and ECG-gated images, bioimpedance technique was utilized to generate respiratory- and dual-gated images. The ability of the bioimpedance technique to monitor intrathoracic respiratory motion was assessed estimating cardiac displacement between end-inspiration and -expiration. The relevance of dual gating was evaluated in left ventricular volume and myocardial wall thickness measurements. An average 7.6  ±  3.3 mm respiratory motion was observed in the study population. Dual gating showed a small but significant increase (4 ml, p = 0.042) in left ventricular myocardial volume compared to plain cardiac gating. In addition, a thinner myocardial wall was observed in dual-gated images (9.3  ±  1.3 mm) compared to cardiac-gated images (11.3  ±  1.3 mm, p = 0.003). This study shows the feasibility of bioimpedance measurements for dual gating in a clinical setting. The method enables simultaneous acquisition of respiratory and cardiac gating signals using a single device with standard ECG electrodes. (paper)

  14. Dosimetric Analysis of Respiratory-Gated Radiotherapy for Hepatocellular Carcinoma

    International Nuclear Information System (INIS)

    Xi Mian; Zhang Li; Liu Mengzhong; Deng Xiaowu; Huang Xiaoyan; Liu Hui

    2011-01-01

    The purpose of this study was to define individualized internal target volume (ITV) for hepatocellular carcinoma (HCC) using 4D computed tomography (4DCT), and to determine the geometric and dosimetric benefits of respiratory gating. Gross tumor volumes (GTVs) were contoured on 10 respiratory phases of 4DCT images for 12 patients with HCC. Three treatment plans were prepared using different planning target volumes (PTVs): (1) PTV 3D , derived from a single helical clinical target volume (CTV) plus conventional margins; (2) PTV 10phases , derived from ITV 10phases , which encompassed all 10 CTVs plus an isotropic margin of 0.8 cm; (3) PTV gating , derived from ITV gating , which encompassed three CTVs within gating-window at end-expiration plus an isotropic margin of 0.8 cm. The PTV 3D was the largest volume for all patients. The ITV-based plans and gating plans spared more normal tissues than 3D plans, especially the liver. Without increasing normal tissue complication probability of the 3D plans, the ITV-based plans allowed for increasing the calculated dose from 50.8 Gy to 54.7 Gy on average, and the gating plans could further escalate the dose to 58.5 Gy. Compared with ITV-based plans, the dosimetric gains with gating plan strongly correlated with GTV mobility in the craniocaudal direction. The ITV-based plans can ensure target coverage with less irradiation of normal tissues compared with 3D plans. Respiratory-gated radiotherapy can further reduce the target volumes to spare more surrounding tissues and allow dose escalation, especially for patients with tumor mobility >1 cm.

  15. Comparison of respiratory surrogates for gated lung radiotherapy without internal fiducials

    International Nuclear Information System (INIS)

    Korreman, S.; Mostafavi, H.; Le, Q.T.; Boyer, A.

    2006-01-01

    An investigation was carried out to compare the ability of two respiratory surrogates to mimic actual lung tumor motion during audio coaching. The investigation employed video clips acquired after patients had had fiducial markers implanted in lung tumors to be used for image-guided stereoscopic radiotherapy. The positions of the markers in the clips were measured within the video frames and used as the standard for tumor volume motion. An external marker was tracked optically during the fluoroscopic acquisitions. An image correlation technique was developed to compute a gating signal from the fluoroscopic images. The correlation gating trace was similar to the optical gating trace in the phase regions of the respiratory cycle used for gating. A cross correlation analysis and comparison of the external optical marker gating with internal fluoroscopic gating was performed. The fluoroscopic image correlation surrogate was found to be superior to the external optical surrogate in the AP-views in four out of six cases. In one of the remaining two cases, the two surrogates performed comparably, while in the last case, the external fiducial trace performed best. It was concluded that fluoroscopic gating based on correlation of native image features in the fluoroscopic images will be adequate for respiratory gating

  16. Comparison of respiratory surrogates for gated lung radiotherapy without internal fiducials

    Energy Technology Data Exchange (ETDEWEB)

    Korreman, S. [Rigshospitalet, Copenhagen (Denmark). Dept. of Radiation Oncology; Mostafavi, H. [Varian Medical Systems, Mountain View, CA (United States). Gintzon Technology Center; Le, Q.T.; Boyer, A. [Stanford Univ. School of Medicine, CA (United States). Dept. of Radiation Oncology

    2006-09-15

    An investigation was carried out to compare the ability of two respiratory surrogates to mimic actual lung tumor motion during audio coaching. The investigation employed video clips acquired after patients had had fiducial markers implanted in lung tumors to be used for image-guided stereoscopic radiotherapy. The positions of the markers in the clips were measured within the video frames and used as the standard for tumor volume motion. An external marker was tracked optically during the fluoroscopic acquisitions. An image correlation technique was developed to compute a gating signal from the fluoroscopic images. The correlation gating trace was similar to the optical gating trace in the phase regions of the respiratory cycle used for gating. A cross correlation analysis and comparison of the external optical marker gating with internal fluoroscopic gating was performed. The fluoroscopic image correlation surrogate was found to be superior to the external optical surrogate in the AP-views in four out of six cases. In one of the remaining two cases, the two surrogates performed comparably, while in the last case, the external fiducial trace performed best. It was concluded that fluoroscopic gating based on correlation of native image features in the fluoroscopic images will be adequate for respiratory gating.

  17. Consideration of the accuracy by variation of respiration in real-time position management respiratory gating system

    International Nuclear Information System (INIS)

    Na, Jun Young; Kang, Tae Young; Beak, Geum Mun; Kwon, Gyeong Tae

    2013-01-01

    Respiratory Gated Radiation Therapy (RGRT) has been carried out using RPM (Real-time Position Management) Respiratory Gating System (version 1.7.5, varian, USA) in Asan Medical Center. This study was to analyze and evaluate the accuracy of Respiratory Gated Radiation Therapy (RGRT) according to variation of respiration. Making variation of respiration using Motion Phantom:QUASAR Programmable Respiratory Motion Phantom (Moudus Medical Device Inc. CANADA) able to adjust respiration pattern randomly was varying period, amplitude and baseline by analyze 50 patient's respiration of lung and liver cancer. One of the variations of respiration is baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. The other variation of respiration is baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm. Experiments were performed in the same way that is used RPM Respiratory Gating System (phase gating, usually 30-70% gating) in Asan Medical Center. It was all exposed radiation under one of the conditions of baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. Under the other condition of baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm equally radiation was exposed. The variations of baseline shifts didn't accurately reflect on phase gating in RPM Respiratory Gating System. This inexactitude makes serious uncertainty in Respiratory Gated Radiation Therapy. So, Must be stabilized breathing of patient before conducting Respiratory Gated Radiation Therapy. also must be monitored breathing of patient in the middle of treatment. If you observe considerable changes of breathing when conducting Respiratory Gated Radiation Therapy. Stopping treatment immediately and then must be need to recheck treatment site using fluoroscopy. If patient's respiration rechecked using fluoroscopy restabilize, it is possible to restart Respiratory Gated Radiation Therapy

  18. External radioactive markers for PET data-driven respiratory gating in positron emission tomography.

    Science.gov (United States)

    Büther, Florian; Ernst, Iris; Hamill, James; Eich, Hans T; Schober, Otmar; Schäfers, Michael; Schäfers, Klaus P

    2013-04-01

    Respiratory gating is an established approach to overcoming respiration-induced image artefacts in PET. Of special interest in this respect are raw PET data-driven gating methods which do not require additional hardware to acquire respiratory signals during the scan. However, these methods rely heavily on the quality of the acquired PET data (statistical properties, data contrast, etc.). We therefore combined external radioactive markers with data-driven respiratory gating in PET/CT. The feasibility and accuracy of this approach was studied for [(18)F]FDG PET/CT imaging in patients with malignant liver and lung lesions. PET data from 30 patients with abdominal or thoracic [(18)F]FDG-positive lesions (primary tumours or metastases) were included in this prospective study. The patients underwent a 10-min list-mode PET scan with a single bed position following a standard clinical whole-body [(18)F]FDG PET/CT scan. During this scan, one to three radioactive point sources (either (22)Na or (18)F, 50-100 kBq) in a dedicated holder were attached the patient's abdomen. The list mode data acquired were retrospectively analysed for respiratory signals using established data-driven gating approaches and additionally by tracking the motion of the point sources in sinogram space. Gated reconstructions were examined qualitatively, in terms of the amount of respiratory displacement and in respect of changes in local image intensity in the gated images. The presence of the external markers did not affect whole-body PET/CT image quality. Tracking of the markers led to characteristic respiratory curves in all patients. Applying these curves for gated reconstructions resulted in images in which motion was well resolved. Quantitatively, the performance of the external marker-based approach was similar to that of the best intrinsic data-driven methods. Overall, the gain in measured tumour uptake from the nongated to the gated images indicating successful removal of respiratory motion

  19. Respiratory gated beam delivery cannot facilitate margin reduction, unless combined with respiratory correlated image guidance

    DEFF Research Database (Denmark)

    Korreman, S.S.; Boyer, A.L.; Juhler-Nøttrup, Trine

    2008-01-01

    PURPOSE/OBJECTIVE: In radiotherapy of targets moving with respiration, beam gating is offered as a means of reducing the target motion. The purpose of this study is to evaluate the safe magnitude of margin reduction for respiratory gated beam delivery. MATERIALS/METHODS: The study is based on data...... for 17 lung cancer patients in separate protocols at Rigshospitalet and Stanford Cancer Center. Respiratory curves for external optical markers and implanted fiducials were collected using equipment based on the RPM system (Varian Medical Systems). A total of 861 respiratory curves represented external...... measurements over 30 fraction treatment courses for 10 patients, and synchronous external/internal measurements in single sessions for seven patients. Variations in respiratory amplitude (simulated coaching) and external/internal phase shifts were simulated by perturbation with realistic values. Variations...

  20. Dynamic gating window for compensation of baseline shift in respiratory-gated radiation therapy

    International Nuclear Information System (INIS)

    Pepin, Eric W.; Wu Huanmei; Shirato, Hiroki

    2011-01-01

    Purpose: To analyze and evaluate the necessity and use of dynamic gating techniques for compensation of baseline shift during respiratory-gated radiation therapy of lung tumors. Methods: Motion tracking data from 30 lung tumors over 592 treatment fractions were analyzed for baseline shift. The finite state model (FSM) was used to identify the end-of-exhale (EOE) breathing phase throughout each treatment fraction. Using duty cycle as an evaluation metric, several methods of end-of-exhale dynamic gating were compared: An a posteriori ideal gating window, a predictive trend-line-based gating window, and a predictive weighted point-based gating window. These methods were evaluated for each of several gating window types: Superior/inferior (SI) gating, anterior/posterior beam, lateral beam, and 3D gating. Results: In the absence of dynamic gating techniques, SI gating gave a 39.6% duty cycle. The ideal SI gating window yielded a 41.5% duty cycle. The weight-based method of dynamic SI gating yielded a duty cycle of 36.2%. The trend-line-based method yielded a duty cycle of 34.0%. Conclusions: Dynamic gating was not broadly beneficial due to a breakdown of the FSM's ability to identify the EOE phase. When the EOE phase was well defined, dynamic gating showed an improvement over static-window gating.

  1. Organ motion study and dosimetric impact of respiratory gating radiotherapy for esophageal cancer

    International Nuclear Information System (INIS)

    Lorchel, F.

    2007-04-01

    Chemoradiotherapy is now the standard treatment for locally advanced or inoperable esophageal carcinoma. In this indication, conformal radiotherapy is generally used. However, prognosis remains poor for these patients. Respiratory gating radiotherapy can decrease healthy tissues irradiation and allows escalation dose in lung, liver and breast cancer. In order to improve radiotherapy technique, we propose to study the feasibility of respiratory gating for esophageal cancer. We will study the respiratory motions of esophageal cancer to optimize target volume delineation, especially the internal margin (I.M.). We will test the correlation between tumour and chest wall displacements to prove that esophageal cancer motions are induced by respiration. This is essential before using free breathing respiratory gating systems. We will work out the dosimetric impact of respiratory gating using various dosimetric analysis parameters. We will compare dosimetric plans at end expiration, end inspiration and deep inspiration with dosimetric plan in free-breathing condition. This will allow us to establish the best respiratory phase to irradiate for each gating system. This dosimetric study will be completed with linear quadratic equivalent uniform dose (E.U.D.) calculation for each volume of interest. Previously, we will do a theoretical study of histogram dose volume gradation to point up its use. (author)

  2. Respiratory gating during stereotactic body radiotherapy for lung cancer reduces tumor position variability.

    Science.gov (United States)

    Saito, Tetsuo; Matsuyama, Tomohiko; Toya, Ryo; Fukugawa, Yoshiyuki; Toyofuku, Takamasa; Semba, Akiko; Oya, Natsuo

    2014-01-01

    We evaluated the effects of respiratory gating on treatment accuracy in lung cancer patients undergoing lung stereotactic body radiotherapy by using electronic portal imaging device (EPID) images. Our study population consisted of 30 lung cancer patients treated with stereotactic body radiotherapy (48 Gy/4 fractions/4 to 9 days). Of these, 14 were treated with- (group A) and 16 without gating (group B); typically the patients whose tumors showed three-dimensional respiratory motion ≧5 mm were selected for gating. Tumor respiratory motion was estimated using four-dimensional computed tomography images acquired during treatment simulation. Tumor position variability during all treatment sessions was assessed by measuring the standard deviation (SD) and range of tumor displacement on EPID images. The two groups were compared for tumor respiratory motion and position variability using the Mann-Whitney U test. The median three-dimensional tumor motion during simulation was greater in group A than group B (9 mm, range 3-30 mm vs. 2 mm, range 0-4 mm; psimulation, tumor position variability in the EPID images was low and comparable to patients treated without gating. This demonstrates the benefit of respiratory gating.

  3. Dual cardiac-respiratory gated PET: implementation and results from a feasibility study

    International Nuclear Information System (INIS)

    Martinez-Moeller, Axel; Zikic, Darko; Navab, Nassir; Botnar, Rene M.; Bundschuh, Ralph A.; Ziegler, Sibylle I.; Schwaiger, Markus; Nekolla, Stephan G.; Howe, William

    2007-01-01

    Spatial resolution in myocardial imaging is impaired by both cardiac and respiratory motion owing to motional blurring. We investigated the feasibility of a dual cardiac-respiratory gated positron emission tomography (PET) acquisition using a clinical PET/computer tomography (CT) scanner. We describe its implementation and present results on the respiratory motion observed. The correlation between diaphragmatic excursion measured by real-time magnetic resonance imaging (MRI) and the expansion of the chest measured with an elastic belt was studied in six subjects. PET list mode acquisitions were then performed in 12 patients, six of them injected with 13 N-ammonia and six with 18 F-FDG. In parallel, the ECG and respiratory signals of the patients were recorded and the list mode file correspondingly sorted using a dual gated approach. Respiratory motion of the heart was quantified by measuring the displacement between the inspiratory and expiratory images in the diastolic phase by means of intensity-based non-rigid image registration. The correlation between diaphragmatic excursion and expansion of the chest was excellent (R 2 = 0.91), validating the ability of the elastic belt to provide an adequate respiratory trigger. Respiratory signals corresponding to the chest expansion showed a large inter-patient variability, requiring adapted algorithms in order to define suitable respiratory gates. Dual gated PET series were successfully acquired for both groups of patients, showing better resolved myocardial walls. The average respiratory motion of the heart measured by PET was 4.8 mm, with its largest component in the craniocaudal direction. Moreover, a deformation of the heart with respiration was observed, with the inferior wall moving significantly more than the anterior. Dual gated cardiac PET studies were performed successfully and showed better resolved myocardial walls as compared with ungated acquisitions. The respiratory motion of the heart presented a

  4. Investigation of patient, tumour and treatment variables affecting residual motion for respiratory-gated radiotherapy

    International Nuclear Information System (INIS)

    George, R; Ramakrishnan, V; Siebers, J V; Chung, T D; Keall, P J

    2006-01-01

    Respiratory gating can reduce the apparent respiratory motion during imaging and treatment; however, residual motion within the gating window remains. Respiratory training can improve respiratory reproducibility and, therefore, the efficacy of respiratory-gated radiotherapy. This study was conducted to determine whether residual motion during respiratory gating is affected by patient, tumour or treatment characteristics. The specific aims of this study were to: (1) identify significant characteristics affecting residual motion, (2) investigate time trends of residual motion over a period of days (inter-session) and (3) investigate time trends of residual motion within the same day (intra-session). Twenty-four lung cancer patients were enrolled in an Institutional Review Board (IRB)-approved protocol. For approximately five sessions, 331 four-minute, respiratory motion traces were acquired with free breathing, audio instructions and audio-visual biofeedback for each patient. The residual motion was quantified by the standard deviation of the displacement within the gating window. The generalized linear model was used to obtain coefficients for each variable within the model and to evaluate the clinical and statistical significance. The statistical significance was determined by a p-value <0.05, while effect sizes of ≥0.1 cm (one standard deviation) were considered clinically significant. This data analysis was applied to patient, tumour and treatment variables. Inter- and intra-session variations were also investigated. The only variable that was significant for both inhale- and exhale-based gating was disease type. In addition, visual-training displacement, breathing type and Karnofsky performance status (KPS) values were significant for inhale-based gating, and dose-per-fraction was significant for exhale-based gating. Temporal respiratory variations within and between sessions were observed for individual patients. However inter- and intra-session analyses did

  5. Investigation of patient, tumour and treatment variables affecting residual motion for respiratory-gated radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    George, R [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA (United States); Ramakrishnan, V [Department of Biostatistics, Virginia Commonwealth University, Richmond, VA (United States); Siebers, J V [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA (United States); Chung, T D [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA (United States); Keall, P J [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA (United States)

    2006-10-21

    Respiratory gating can reduce the apparent respiratory motion during imaging and treatment; however, residual motion within the gating window remains. Respiratory training can improve respiratory reproducibility and, therefore, the efficacy of respiratory-gated radiotherapy. This study was conducted to determine whether residual motion during respiratory gating is affected by patient, tumour or treatment characteristics. The specific aims of this study were to: (1) identify significant characteristics affecting residual motion, (2) investigate time trends of residual motion over a period of days (inter-session) and (3) investigate time trends of residual motion within the same day (intra-session). Twenty-four lung cancer patients were enrolled in an Institutional Review Board (IRB)-approved protocol. For approximately five sessions, 331 four-minute, respiratory motion traces were acquired with free breathing, audio instructions and audio-visual biofeedback for each patient. The residual motion was quantified by the standard deviation of the displacement within the gating window. The generalized linear model was used to obtain coefficients for each variable within the model and to evaluate the clinical and statistical significance. The statistical significance was determined by a p-value <0.05, while effect sizes of {>=}0.1 cm (one standard deviation) were considered clinically significant. This data analysis was applied to patient, tumour and treatment variables. Inter- and intra-session variations were also investigated. The only variable that was significant for both inhale- and exhale-based gating was disease type. In addition, visual-training displacement, breathing type and Karnofsky performance status (KPS) values were significant for inhale-based gating, and dose-per-fraction was significant for exhale-based gating. Temporal respiratory variations within and between sessions were observed for individual patients. However inter- and intra-session analyses did

  6. Respiratory motion management using audio-visual biofeedback for respiratory-gated radiotherapy of synchrotron-based pulsed heavy-ion beam delivery

    International Nuclear Information System (INIS)

    He, Pengbo; Ma, Yuanyuan; Huang, Qiyan; Yan, Yuanlin; Li, Qiang; Liu, Xinguo; Dai, Zhongying; Zhao, Ting; Fu, Tingyan; Shen, Guosheng

    2014-01-01

    Purpose: To efficiently deliver respiratory-gated radiation during synchrotron-based pulsed heavy-ion radiotherapy, a novel respiratory guidance method combining a personalized audio-visual biofeedback (BFB) system, breath hold (BH), and synchrotron-based gating was designed to help patients synchronize their respiratory patterns with synchrotron pulses and to overcome typical limitations such as low efficiency, residual motion, and discomfort. Methods: In-house software was developed to acquire body surface marker positions and display BFB, gating signals, and real-time beam profiles on a LED screen. Patients were prompted to perform short BHs or short deep breath holds (SDBH) with the aid of BFB following a personalized standard BH/SDBH (stBH/stSDBH) guiding curve or their own representative BH/SDBH (reBH/reSDBH) guiding curve. A practical simulation was performed for a group of 15 volunteers to evaluate the feasibility and effectiveness of this method. Effective dose rates (EDRs), mean absolute errors between the guiding curves and the measured curves, and mean absolute deviations of the measured curves were obtained within 10%–50% duty cycles (DCs) that were synchronized with the synchrotron’s flat-top phase. Results: All maneuvers for an individual volunteer took approximately half an hour, and no one experienced discomfort during the maneuvers. Using the respiratory guidance methods, the magnitude of residual motion was almost ten times less than during nongated irradiation, and increases in the average effective dose rate by factors of 2.39–4.65, 2.39–4.59, 1.73–3.50, and 1.73–3.55 for the stBH, reBH, stSDBH, and reSDBH guiding maneuvers, respectively, were observed in contrast with conventional free breathing-based gated irradiation, depending on the respiratory-gated duty cycle settings. Conclusions: The proposed respiratory guidance method with personalized BFB was confirmed to be feasible in a group of volunteers. Increased effective dose

  7. Respiratory motion management using audio-visual biofeedback for respiratory-gated radiotherapy of synchrotron-based pulsed heavy-ion beam delivery

    Energy Technology Data Exchange (ETDEWEB)

    He, Pengbo; Ma, Yuanyuan; Huang, Qiyan; Yan, Yuanlin [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000 (China); School of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Qiang, E-mail: liqiang@impcas.ac.cn; Liu, Xinguo; Dai, Zhongying; Zhao, Ting; Fu, Tingyan; Shen, Guosheng [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000 (China)

    2014-11-01

    Purpose: To efficiently deliver respiratory-gated radiation during synchrotron-based pulsed heavy-ion radiotherapy, a novel respiratory guidance method combining a personalized audio-visual biofeedback (BFB) system, breath hold (BH), and synchrotron-based gating was designed to help patients synchronize their respiratory patterns with synchrotron pulses and to overcome typical limitations such as low efficiency, residual motion, and discomfort. Methods: In-house software was developed to acquire body surface marker positions and display BFB, gating signals, and real-time beam profiles on a LED screen. Patients were prompted to perform short BHs or short deep breath holds (SDBH) with the aid of BFB following a personalized standard BH/SDBH (stBH/stSDBH) guiding curve or their own representative BH/SDBH (reBH/reSDBH) guiding curve. A practical simulation was performed for a group of 15 volunteers to evaluate the feasibility and effectiveness of this method. Effective dose rates (EDRs), mean absolute errors between the guiding curves and the measured curves, and mean absolute deviations of the measured curves were obtained within 10%–50% duty cycles (DCs) that were synchronized with the synchrotron’s flat-top phase. Results: All maneuvers for an individual volunteer took approximately half an hour, and no one experienced discomfort during the maneuvers. Using the respiratory guidance methods, the magnitude of residual motion was almost ten times less than during nongated irradiation, and increases in the average effective dose rate by factors of 2.39–4.65, 2.39–4.59, 1.73–3.50, and 1.73–3.55 for the stBH, reBH, stSDBH, and reSDBH guiding maneuvers, respectively, were observed in contrast with conventional free breathing-based gated irradiation, depending on the respiratory-gated duty cycle settings. Conclusions: The proposed respiratory guidance method with personalized BFB was confirmed to be feasible in a group of volunteers. Increased effective dose

  8. Fully automated intrinsic respiratory and cardiac gating for small animal CT

    Energy Technology Data Exchange (ETDEWEB)

    Kuntz, J; Baeuerle, T; Semmler, W; Bartling, S H [Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg (Germany); Dinkel, J [Department of Radiology, German Cancer Research Center, Heidelberg (Germany); Zwick, S [Department of Diagnostic Radiology, Medical Physics, Freiburg University (Germany); Grasruck, M [Siemens Healthcare, Forchheim (Germany); Kiessling, F [Chair of Experimental Molecular Imaging, RWTH-Aachen University, Medical Faculty, Aachen (Germany); Gupta, R [Department of Radiology, Massachusetts General Hospital, Boston, MA (United States)], E-mail: j.kuntz@dkfz.de

    2010-04-07

    A fully automated, intrinsic gating algorithm for small animal cone-beam CT is described and evaluated. A parameter representing the organ motion, derived from the raw projection images, is used for both cardiac and respiratory gating. The proposed algorithm makes it possible to reconstruct motion-corrected still images as well as to generate four-dimensional (4D) datasets representing the cardiac and pulmonary anatomy of free-breathing animals without the use of electrocardiogram (ECG) or respiratory sensors. Variation analysis of projections from several rotations is used to place a region of interest (ROI) on the diaphragm. The ROI is cranially extended to include the heart. The centre of mass (COM) variation within this ROI, the filtered frequency response and the local maxima are used to derive a binary motion-gating parameter for phase-sensitive gated reconstruction. This algorithm was implemented on a flat-panel-based cone-beam CT scanner and evaluated using a moving phantom and animal scans (seven rats and eight mice). Volumes were determined using a semiautomatic segmentation. In all cases robust gating signals could be obtained. The maximum volume error in phantom studies was less than 6%. By utilizing extrinsic gating via externally placed cardiac and respiratory sensors, the functional parameters (e.g. cardiac ejection fraction) and image quality were equivalent to this current gold standard. This algorithm obviates the necessity of both gating hardware and user interaction. The simplicity of the proposed algorithm enables adoption in a wide range of small animal cone-beam CT scanners.

  9. SU-E-J-159: Analysis of Total Imaging Uncertainty in Respiratory-Gated Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, J; Okuda, T [Toyota memorial hospital, Toyota, Aichi (Japan); Sakaino, S; Yokota, N [Suzukake central hospital, Hamamatsu, Shizuoka (Japan)

    2015-06-15

    Purpose: In respiratory-gated radiotherapy, the gating phase during treatment delivery needs to coincide with the corresponding phase determined during the treatment plan. However, because radiotherapy is performed based on the image obtained for the treatment plan, the time delay, motion artifact, volume effect, and resolution in the images are uncertain. Thus, imaging uncertainty is the most basic factor that affects the localization accuracy. Therefore, these uncertainties should be analyzed. This study aims to analyze the total imaging uncertainty in respiratory-gated radiotherapy. Methods: Two factors of imaging uncertainties related to respiratory-gated radiotherapy were analyzed. First, CT image was used to determine the target volume and 4D treatment planning for the Varian Realtime Position Management (RPM) system. Second, an X-ray image was acquired for image-guided radiotherapy (IGRT) for the BrainLAB ExacTrac system. These factors were measured using a respiratory gating phantom. The conditions applied during phantom operation were as follows: respiratory wave form, sine curve; respiratory cycle, 4 s; phantom target motion amplitude, 10, 20, and 29 mm (which is maximum phantom longitudinal motion). The target and cylindrical marker implanted in the phantom coverage of the CT images was measured and compared with the theoretically calculated coverage from the phantom motion. The theoretical position of the cylindrical marker implanted in the phantom was compared with that acquired from the X-ray image. The total imaging uncertainty was analyzed from these two factors. Results: In the CT image, the uncertainty between the target and cylindrical marker’s actual coverage and the coverage of CT images was 1.19 mm and 2.50mm, respectively. In the Xray image, the uncertainty was 0.39 mm. The total imaging uncertainty from the two factors was 1.62mm. Conclusion: The total imaging uncertainty in respiratory-gated radiotherapy was clinically acceptable. However

  10. SU-E-J-159: Analysis of Total Imaging Uncertainty in Respiratory-Gated Radiotherapy

    International Nuclear Information System (INIS)

    Suzuki, J; Okuda, T; Sakaino, S; Yokota, N

    2015-01-01

    Purpose: In respiratory-gated radiotherapy, the gating phase during treatment delivery needs to coincide with the corresponding phase determined during the treatment plan. However, because radiotherapy is performed based on the image obtained for the treatment plan, the time delay, motion artifact, volume effect, and resolution in the images are uncertain. Thus, imaging uncertainty is the most basic factor that affects the localization accuracy. Therefore, these uncertainties should be analyzed. This study aims to analyze the total imaging uncertainty in respiratory-gated radiotherapy. Methods: Two factors of imaging uncertainties related to respiratory-gated radiotherapy were analyzed. First, CT image was used to determine the target volume and 4D treatment planning for the Varian Realtime Position Management (RPM) system. Second, an X-ray image was acquired for image-guided radiotherapy (IGRT) for the BrainLAB ExacTrac system. These factors were measured using a respiratory gating phantom. The conditions applied during phantom operation were as follows: respiratory wave form, sine curve; respiratory cycle, 4 s; phantom target motion amplitude, 10, 20, and 29 mm (which is maximum phantom longitudinal motion). The target and cylindrical marker implanted in the phantom coverage of the CT images was measured and compared with the theoretically calculated coverage from the phantom motion. The theoretical position of the cylindrical marker implanted in the phantom was compared with that acquired from the X-ray image. The total imaging uncertainty was analyzed from these two factors. Results: In the CT image, the uncertainty between the target and cylindrical marker’s actual coverage and the coverage of CT images was 1.19 mm and 2.50mm, respectively. In the Xray image, the uncertainty was 0.39 mm. The total imaging uncertainty from the two factors was 1.62mm. Conclusion: The total imaging uncertainty in respiratory-gated radiotherapy was clinically acceptable. However

  11. Data-driven gating in PET: Influence of respiratory signal noise on motion resolution.

    Science.gov (United States)

    Büther, Florian; Ernst, Iris; Frohwein, Lynn Johann; Pouw, Joost; Schäfers, Klaus Peter; Stegger, Lars

    2018-05-21

    Data-driven gating (DDG) approaches for positron emission tomography (PET) are interesting alternatives to conventional hardware-based gating methods. In DDG, the measured PET data themselves are utilized to calculate a respiratory signal, that is, subsequently used for gating purposes. The success of gating is then highly dependent on the statistical quality of the PET data. In this study, we investigate how this quality determines signal noise and thus motion resolution in clinical PET scans using a center-of-mass-based (COM) DDG approach, specifically with regard to motion management of target structures in future radiotherapy planning applications. PET list mode datasets acquired in one bed position of 19 different radiotherapy patients undergoing pretreatment [ 18 F]FDG PET/CT or [ 18 F]FDG PET/MRI were included into this retrospective study. All scans were performed over a region with organs (myocardium, kidneys) or tumor lesions of high tracer uptake and under free breathing. Aside from the original list mode data, datasets with progressively decreasing PET statistics were generated. From these, COM DDG signals were derived for subsequent amplitude-based gating of the original list mode file. The apparent respiratory shift d from end-expiration to end-inspiration was determined from the gated images and expressed as a function of signal-to-noise ratio SNR of the determined gating signals. This relation was tested against additional 25 [ 18 F]FDG PET/MRI list mode datasets where high-precision MR navigator-like respiratory signals were available as reference signal for respiratory gating of PET data, and data from a dedicated thorax phantom scan. All original 19 high-quality list mode datasets demonstrated the same behavior in terms of motion resolution when reducing the amount of list mode events for DDG signal generation. Ratios and directions of respiratory shifts between end-respiratory gates and the respective nongated image were constant over all

  12. In Vivo Respiratory-Gated Micro-CT Imaging in Small-Animal Oncology Models

    Directory of Open Access Journals (Sweden)

    Dawn Cavanaugh

    2004-01-01

    Full Text Available Micro-computed tomography (micro-CT is becoming an accepted research tool for the noninvasive examination of laboratory animals such as mice and rats, but to date, in vivo scanning has largely been limited to the evaluation of skeletal tissues. We use a commercially available micro-CT device to perform respiratory gated in vivo acquisitions suitable for thoracic imaging. The instrument is described, along with the scan protocol and animal preparation techniques. Preliminary results confirm that lung tumors as small as 1 mm in diameter are visible in vivo with these methods. Radiation dose was evaluated using several approaches, and was found to be approximately 0.15 Gy for this respiratory-gated micro-CT imaging protocol. The combination of high-resolution CT imaging and respiratory-gated acquisitions appears well-suited to serial in vivo scanning.

  13. Respiratory-Gated Positron Emission Tomography and Breath-Hold Computed Tomography Coupling to Reduce the Influence of Respiratory Motion: Methodology and Feasibility

    International Nuclear Information System (INIS)

    Daouk, J.; Fin, L.; Bailly, P.; Meyer, M.E.

    2009-01-01

    Background: Respiratory motion causes uptake in positron emission tomography (PET) images of chest and abdominal structures to be blurred and reduced in intensity. Purpose: To compare two respiratory-gated PET binning methods (based on frequency and amplitude analyses of the respiratory signal) and to propose a 'BH-based' method based on an additional breath-hold computed tomography (CT) acquisition. Material and Methods: Respiratory-gated PET consists in list-mode (LM) acquisition with simultaneous respiratory signal recording. A phantom study featured rectilinear movement of a 0.5-ml sphere filled with 18 F-fluorodeoxyglucose ( 18 F-FDG) solution, placed in a radioactive background (sphere-to-background contrast 6:1). Two patients were also examined. Three figures of merit were calculated: the target-to-background ratio profile (TBRP) in the axial direction through the uptake (i.e., the sphere or lesion), full-width-at-half-maximum (FWHM) values, and maximized standard uptake values (SUVmax). Results: In the phantom study, the peak TBRP was 0.9 for non-gated volume, 1.83 for BH-based volume, and varied between 1.13 and 1.73 for Freq-based volumes and between 1.34 and 1.66 for Amp-based volumes. A reference volume (REF-static) was also acquired for the phantom (in a static, 'expiratory' state), with a peak TBRP at 1.88. TBRPs were computed for patient data, with higher peak values for all gated volumes than for non-gated volumes. Conclusion: Respiratory-gated PET acquisition reduces the blurring effect and increases image contrast. However, Freq-based and Amp-based volumes are still influenced by inappropriate attenuation correction and misregistration of mobile lesions on CT images. The proposed BH-based method both reduces motion artifacts and improves PET-CT registration

  14. Evaluation and reduction of respiratory motion artifacts in small animal SPECT with GATE

    International Nuclear Information System (INIS)

    Lee, C.-L.; Park, S.-J.; Kim, H.-J.

    2015-01-01

    The degradation of image quality caused by respiration is a major impediment to accurate lesion detection in single photon emission computed tomography (SPECT) imaging. This study was performed to evaluate the effects of lung motion on image quantification. A small animal SPECT system with NaI(Tl) was modeled in the Geant4 application for tomographic emission (GATE) simulation for a lung lesion using a 4D mouse whole-body phantom. SPECT images were obtained using 120 projection views acquired from 0 o to 360 o with a 3 o step. Slices were reconstructed using ordered subsets expectation maximization (OS-EM) without attenuation correction with five iterations and four subsets. Image quality was compared between the static mode without respiratory motion, and dynamic mode with respiratory motion in terms of spatial resolution was measured by the full width at half maximum (FWHM), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). The FWHM of the non-gated image and the respiratory gated image were also compared. Spatial resolution improved as activity increased and lesion diameter decreased in the static and dynamic modes. The SNR and CNR increased significantly as lesion activity increased and lesion diameter decreased. Our results show that respiratory motion leads to reduced contrast and quantitative accuracy and that image quantification depends on both the amplitude and the pattern of the respiratory motion. We verified that respiratory motion can have a major effect on the accuracy of measurement of lung lesions and that respiratory gating can reduce activity smearing on SPECT images

  15. Dosimetric evaluation of the interplay effect in respiratory-gated RapidArc radiation therapy

    International Nuclear Information System (INIS)

    Riley, Craig; Yang, Yong; Li, Tianfang; Zhang, Yongqian; Heron, Dwight E.; Huq, M. Saiful

    2014-01-01

    Purpose: Volumetric modulated arc therapy (VMAT) with gating capability has had increasing adoption in many clinics in the United States. In this new technique, dose rate, gantry rotation speed, and the leaf motion speed of multileaf collimators (MLCs) are modulated dynamically during gated beam delivery to achieve highly conformal dose coverage of the target and normal tissue sparing. Compared with the traditional gated intensity-modulated radiation therapy technique, this complicated beam delivery technique may result in larger dose errors due to the intrafraction tumor motion. The purpose of this work is to evaluate the dosimetric influence of the interplay effect for the respiration-gated VMAT technique (RapidArc, Varian Medical Systems, Palo Alto, CA). Our work consisted of two parts: (1) Investigate the interplay effect for different target residual errors during gated RapidArc delivery using a one-dimensional moving phantom capable of producing stable sinusoidal movement; (2) Evaluate the dosimetric influence in ten clinical patients’ treatment plans using a moving phantom driven with a patient-specific respiratory curve. Methods: For the first part of this study, four plans were created with a spherical target for varying residual motion of 0.25, 0.5, 0.75, and 1.0 cm. Appropriate gating windows were applied for each. The dosimetric effect was evaluated using EDR2 film by comparing the gated delivery with static delivery. For the second part of the project, ten gated lung stereotactic body radiotherapy cases were selected and reoptimized to be delivered by the gated RapidArc technique. These plans were delivered to a phantom, and again the gated treatments were compared to static deliveries by the same methods. Results: For regular sinusoidal motion, the dose delivered to the target was not substantially affected by the gating windows when evaluated with the gamma statistics, suggesting the interplay effect has a small role in respiratory-gated Rapid

  16. Dosimetric evaluation of the interplay effect in respiratory-gated RapidArc radiation therapy.

    Science.gov (United States)

    Riley, Craig; Yang, Yong; Li, Tianfang; Zhang, Yongqian; Heron, Dwight E; Huq, M Saiful

    2014-01-01

    Volumetric modulated arc therapy (VMAT) with gating capability has had increasing adoption in many clinics in the United States. In this new technique, dose rate, gantry rotation speed, and the leaf motion speed of multileaf collimators (MLCs) are modulated dynamically during gated beam delivery to achieve highly conformal dose coverage of the target and normal tissue sparing. Compared with the traditional gated intensity-modulated radiation therapy technique, this complicated beam delivery technique may result in larger dose errors due to the intrafraction tumor motion. The purpose of this work is to evaluate the dosimetric influence of the interplay effect for the respiration-gated VMAT technique (RapidArc, Varian Medical Systems, Palo Alto, CA). Our work consisted of two parts: (1) Investigate the interplay effect for different target residual errors during gated RapidArc delivery using a one-dimensional moving phantom capable of producing stable sinusoidal movement; (2) Evaluate the dosimetric influence in ten clinical patients' treatment plans using a moving phantom driven with a patient-specific respiratory curve. For the first part of this study, four plans were created with a spherical target for varying residual motion of 0.25, 0.5, 0.75, and 1.0 cm. Appropriate gating windows were applied for each. The dosimetric effect was evaluated using EDR2 film by comparing the gated delivery with static delivery. For the second part of the project, ten gated lung stereotactic body radiotherapy cases were selected and reoptimized to be delivered by the gated RapidArc technique. These plans were delivered to a phantom, and again the gated treatments were compared to static deliveries by the same methods. For regular sinusoidal motion, the dose delivered to the target was not substantially affected by the gating windows when evaluated with the gamma statistics, suggesting the interplay effect has a small role in respiratory-gated RapidArc therapy. Varied results were

  17. Motion management within two respiratory-gating windows: feasibility study of dual quasi-breath-hold technique in gated medical procedures

    International Nuclear Information System (INIS)

    Kim, Taeho; Kim, Siyong; Youn, Kaylin K; Park, Yang-Kyun; Keall, Paul; Lee, Rena

    2014-01-01

    A dual quasi-breath-hold (DQBH) technique is proposed for respiratory motion management (a hybrid technique combining breathing-guidance with breath-hold task in the middle). The aim of this study is to test a hypothesis that the DQBH biofeedback system improves both the capability of motion management and delivery efficiency. Fifteen healthy human subjects were recruited for two respiratory motion measurements (free breathing and DQBH biofeedback breathing for 15 min). In this study, the DQBH biofeedback system utilized the abdominal position obtained using an real-time position management (RPM) system (Varian Medical Systems, Palo Alto, USA) to audio-visually guide a human subject for 4 s breath-hold at EOI and 90% EOE (EOE 90% ) to improve delivery efficiency. We investigated the residual respiratory motion and the delivery efficiency (duty-cycle) of abdominal displacement within the gating window. The improvement of the abdominal motion reproducibility was evaluated in terms of cycle-to-cycle displacement variability, respiratory period and baseline drift. The DQBH biofeedback system improved the abdominal motion management capability compared to that with free breathing. With a phase based gating (mean ± std: 55  ±  5%), the averaged root mean square error (RMSE) of the abdominal displacement in the dual-gating windows decreased from 2.26 mm of free breathing to 1.16 mm of DQBH biofeedback (p-value = 0.007). The averaged RMSE of abdominal displacement over the entire respiratory cycles reduced from 2.23 mm of free breathing to 1.39 mm of DQBH biofeedback breathing in the dual-gating windows (p-value = 0.028). The averaged baseline drift dropped from 0.9 mm min −1 with free breathing to 0.09 mm min −1 with DQBH biofeedback (p-value = 0.048). The averaged duty-cycle with an 1 mm width of displacement bound increased from 15% of free breathing to 26% of DQBH biofeedback (p-value = 0.003). The study demonstrated that the DQBH

  18. Issues in quantification of registered respiratory gated PET/CT in the lung

    Science.gov (United States)

    Cuplov, Vesna; Holman, Beverley F.; McClelland, Jamie; Modat, Marc; Hutton, Brian F.; Thielemans, Kris

    2018-01-01

    PET/CT quantification of lung tissue is limited by several difficulties: the lung density and local volume changes during respiration, the anatomical mismatch between PET and CT and the relative contributions of tissue, air and blood to the PET signal (the tissue fraction effect). Air fraction correction (AFC) has been shown to improve PET image quantification in the lungs. Methods to correct for the movement and anatomical mismatch involve respiratory gating and image registration techniques. While conventional registration methods only account for spatial mismatch, the Jacobian determinant of the deformable registration transformation field can be used to estimate local volume changes and could therefore potentially be used to correct (i.e. Jacobian Correction, JC) the PET signal for changes in concentration due to local volume changes. This work aims to investigate the relationship between variations in the lung due to respiration, specifically density, tracer concentration and local volume changes. In particular, we study the effect of AFC and JC on PET quantitation after registration of respiratory gated PET/CT patient data. Six patients suffering from lung cancer with solitary pulmonary nodules underwent 18 F-FDG PET/cine-CT. The PET data were gated into six respiratory gates using displacement gating based on a real-time position management (RPM) signal and reconstructed with matched gated CT. The PET tracer concentration and tissue density were extracted from registered gated PET and CT images before and after corrections (AFC or JC) and compared to the values from the reference images. Before correction, we observed a linear correlation between the PET tracer concentration values and density. Across all gates and patients, the maximum relative change in PET tracer concentration before (after) AFC was found to be 16.2% (4.1%) and the maximum relative change in tissue density and PET tracer concentration before (after) JC was found to be 17.1% (5.5%) and 16

  19. Imaging quality and effective radiation dose of prospective ECG-gated axial multidetector row computed tomography coronary angiography

    International Nuclear Information System (INIS)

    Capunay, C.; Carrascosa, P.; Vallejos, J.; Deviggiano, A.; Pollono, P.M.; Garcia, M.J.

    2011-01-01

    Objective. To determine the imaging quality and effective radiation dose (ERD) of prospective ECG-gated multidetector row computed tomography coronary angiography (PMDCTCA) compared to retrospective ECG-gating (RMDCT-CA). Materials and Methods. Forty-five PMDCT-CA scans were retrospectively reviewed for assessing imaging quality and ERD, and compared to 90 RMDCT-CA scans performed with (n=45) and without (n=45) tube current modulation, selected from our database on the basis of similar demographical characteristics. ERD was compared between all three groups. Imaging quality was assessed by two independent observers and compared to the imaging quality of the group of RMDCT-CA scans performed with tube current modulation. The interobserver variability was also determined. Results. There were no significant differences in imaging quality between the two groups. Interobserver variability was k=0.92 (95 % CI: 0.87-0.96). The ERD (mean ± SD) using PMDCT-CA was 2.88 ± 0.37 mSv compared to 10.50 ± 1.15 mSv (p [es

  20. Respiratory gating based on internal electromagnetic motion monitoring during stereotactic liver radiation therapy: First results.

    Science.gov (United States)

    Poulsen, Per Rugaard; Worm, Esben Schjødt; Hansen, Rune; Larsen, Lars Peter; Grau, Cai; Høyer, Morten

    2015-01-01

    Intrafraction motion may compromise the target dose in stereotactic body radiation therapy (SBRT) of tumors in the liver. Respiratory gating can improve the treatment delivery, but gating based on an external surrogate signal may be inaccurate. This is the first paper reporting on respiratory gating based on internal electromagnetic monitoring during liver SBRT. Two patients with solitary liver metastases were treated with respiratory-gated SBRT guided by three implanted electromagnetic transponders. The treatment was delivered in end-exhale with beam-on when the centroid of the three transponders deviated less than 3 mm [left-right (LR) and anterior-posterior (AP) directions] and 4mm [cranio-caudal (CC)] from the planned position. For each treatment fraction, log files were used to determine the transponder motion during beam-on in the actual gated treatments and in simulated treatments without gating. The motion was used to reconstruct the dose to the clinical target volume (CTV) with and without gating. The reduction in D95 (minimum dose to 95% of the CTV) relative to the plan was calculated for both treatment courses. With gating the maximum course mean (standard deviation) geometrical error in any direction was 1.2 mm (1.8 mm). Without gating the course mean error would mainly increase for Patient 1 [to -2.8 mm (1.6 mm) (LR), 7.1 mm (5.8 mm) (CC), -2.6 mm (2.8mm) (AP)] due to a large systematic cranial baseline drift at each fraction. The errors without gating increased only slightly for Patient 2. The reduction in CTV D95 was 0.5% (gating) and 12.1% (non-gating) for Patient 1 and 0.3% (gating) and 1.7% (non-gating) for Patient 2. The mean duty cycle was 55%. Respiratory gating based on internal electromagnetic motion monitoring was performed for two liver SBRT patients. The gating added robustness to the dose delivery and ensured a high CTV dose even in the presence of large intrafraction motion.

  1. End-expiration respiratory gating for a high-resolution stationary cardiac SPECT system

    International Nuclear Information System (INIS)

    Chan, Chung; Sinusas, Albert J; Liu, Chi; Harris, Mark; Le, Max; Biondi, James; Grobshtein, Yariv; Liu, Yi-Hwa

    2014-01-01

    Respiratory and cardiac motions can degrade myocardial perfusion SPECT (MPS) image quality and reduce defect detection and quantitative accuracy. In this study, we developed a dual respiratory and cardiac gating system for a high-resolution fully stationary cardiac SPECT scanner in order to improve the image quality and defect detection. Respiratory motion was monitored using a compressive sensor pillow connected to a dual respiratory–cardiac gating box, which sends cardiac triggers only during end-expiration phases to the single cardiac trigger input on the SPECT scanners. The listmode data were rebinned retrospectively into end-expiration frames for respiratory motion reduction or eight cardiac gates only during end-expiration phases to compensate for both respiratory and cardiac motions. The proposed method was first validated on a motion phantom in the presence and absence of multiple perfusion defects, and then applied on 11 patient studies with and without perfusion defects. In the normal phantom studies, the end-expiration gated SPECT (EXG-SPECT) reduced respiratory motion blur and increased myocardium to blood pool contrast by 51.2% as compared to the ungated images. The proposed method also yielded an average of 11.2% increase in myocardium to defect contrast as compared to the ungated images in the phantom studies with perfusion defects. In the patient studies, EXG-SPECT significantly improved the myocardium to blood pool contrast (p < 0.005) by 24% on average as compared to the ungated images, and led to improved perfusion uniformity across segments on polar maps for normal patients. For a patient with defect, EXG-SPECT improved the defect contrast and definition. The dual respiratory–cardiac gating further reduced the blurring effect, increased the myocardium to blood pool contrast significantly by 36% (p < 0.05) compared to EXG-SPECT, and further improved defect characteristics and visualization of fine structures at the expense of increased

  2. Contrast-enhanced specific absorption rate-efficient 3D cardiac cine with respiratory-triggered radiofrequency gating.

    Science.gov (United States)

    Henningsson, Markus; Chan, Raymond H; Goddu, Beth; Goepfert, Lois A; Razavi, Reza; Botnar, Rene M; Schaeffter, Tobias; Nezafat, Reza

    2013-04-01

    To investigate the use of radiofrequency (RF) gating in conjunction with a paramagnetic contrast agent to reduce the specific absorption rate (SAR) and increase the blood-myocardium contrast in balanced steady-state free precession (bSSFP) 3D cardiac cine. RF gating was implemented by synchronizing the RF-excitation with an external respiratory sensor (bellows), which could additionally be used for respiratory gating. For reference, respiratory-gated 3D cine images were acquired without RF gating. Free-breathing 3D cine images were acquired in eight healthy subjects before and after contrast injection (Gd-BOPTA) and compared to breath-hold 2D cine. RF-gated 3D cine reduced the SAR by nearly 40% without introducing significant artifacts while providing left ventricle (LV) measurements similar to those obtained with 2D cine. The contrast-to-noise ratio (CNR) was significantly higher for 3D cine compared to 2D cine, both before and after contrast injection; however, no statistically significant CNR increase was observed for the postcontrast 3D cine compared to the precontrast acquisitions. Respiratory-triggered RF gating significantly reduces SAR in 3D cine acquisitions, which may enable a more widespread clinical use of 3D cine. Furthermore, CNR of 3D bSSFP cine is higher than of 2D and administration of Gd-BOPTA does not improve the CNR of 3D cine. Copyright © 2012 Wiley Periodicals, Inc.

  3. Respiratory lung motion analysis using a nonlinear motion correction technique for respiratory-gated lung perfusion SPECT images

    International Nuclear Information System (INIS)

    Ue, Hidenori; Haneishi, Hideaki; Iwanaga, Hideyuki; Suga, Kazuyoshi

    2007-01-01

    This study evaluated the respiratory motion of lungs using a nonlinear motion correction technique for respiratory-gated single photon emission computed tomography (SPECT) images. The motion correction technique corrects the respiratory motion of the lungs nonlinearly between two-phase images obtained by respiratory-gated SPECT. The displacement vectors resulting from respiration can be computed at every location of the lungs. Respiratory lung motion analysis is carried out by calculating the mean value of the body axis component of the displacement vector in each of the 12 small regions into which the lungs were divided. In order to enable inter-patient comparison, the 12 mean values were normalized by the length of the lung region along the direction of the body axis. This method was applied to 25 Technetium (Tc)-99m-macroaggregated albumin (MAA) perfusion SPECT images, and motion analysis results were compared with the diagnostic results. It was confirmed that the respiratory lung motion reflects the ventilation function. A statistically significant difference in the amount of the respiratory lung motion was observed between the obstructive pulmonary diseases and other conditions, based on an unpaired Student's t test (P<0.0001). A difference in the motion between normal lungs and lungs with a ventilation obstruction was detected by the proposed method. This method is effective for evaluating obstructive pulmonary diseases such as pulmonary emphysema and diffuse panbronchiolitis. (author)

  4. Systematic errors in respiratory gating due to intrafraction deformations of the liver

    International Nuclear Information System (INIS)

    Siebenthal, Martin von; Szekely, Gabor; Lomax, Antony J.; Cattin, Philippe C.

    2007-01-01

    This article shows the limitations of respiratory gating due to intrafraction deformations of the right liver lobe. The variability of organ shape and motion over tens of minutes was taken into account for this evaluation, which closes the gap between short-term analysis of a few regular cycles, as it is possible with 4DCT, and long-term analysis of interfraction motion. Time resolved MR volumes (4D MR sequences) were reconstructed for 12 volunteers and subsequent non-rigid registration provided estimates of the 3D trajectories of points within the liver over time. The full motion during free breathing and its distribution over the liver were quantified and respiratory gating was simulated to determine the gating accuracy for different gating signals, duty cycles, and different intervals between patient setup and treatment. Gating effectively compensated for the respiratory motion within short sequences (3 min), but deformations, mainly in the anterior inferior part (Couinaud segments IVb and V), led to systematic deviations from the setup position of more than 5 mm in 7 of 12 subjects after 20 min. We conclude that measurements over a few breathing cycles should not be used as a proof of accurate reproducibility of motion, not even within the same fraction, if it is longer than a few minutes. Although the diaphragm shows the largest magnitude of motion, it should not be used to assess the gating accuracy over the entire liver because the reproducibility is typically much more limited in inferior parts. Simple gating signals, such as the trajectory of skin motion, can detect the exhalation phase, but do not allow for an absolute localization of the complete liver over longer periods because the drift of these signals does not necessarily correlate with the internal drift

  5. Influence of Respiratory Gating, Image Filtering, and Animal Positioning on High-Resolution Electrocardiography-Gated Murine Cardiac Single-Photon Emission Computed Tomography

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2015-01-01

    Full Text Available Cardiac parameters obtained from single-photon emission computed tomographic (SPECT images can be affected by respiratory motion, image filtering, and animal positioning. We investigated the influence of these factors on ultra-high-resolution murine myocardial perfusion SPECT. Five mice were injected with 99m technetium (99mTc-tetrofosmin, and each was scanned in supine and prone positions in a U-SPECT-II scanner with respiratory and electrocardiographic (ECG gating. ECG-gated SPECT images were created without applying respiratory motion correction or with two different respiratory motion correction strategies. The images were filtered with a range of three-dimensional gaussian kernels, after which end-diastolic volumes (EDVs, end-systolic volumes (ESVs, and left ventricular ejection fractions were calculated. No significant differences in the measured cardiac parameters were detected when any strategy to reduce or correct for respiratory motion was applied, whereas big differences (> 5% in EDV and ESV were found with regard to different positioning of animals. A linear relationship (p < .001 was found between the EDV or ESV and the kernel size of the gaussian filter. In short, respiratory gating did not significantly affect the cardiac parameters of mice obtained with ultra-high-resolution SPECT, whereas the position of the animals and the image filters should be the same in a comparative study with multiple scans to avoid systematic differences in measured cardiac parameters.

  6. 3-D cardiac MRI in free-breathing newborns and infants: when is respiratory gating necessary?

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Achim [University Hospital of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); University Hospital of Tuebingen, Department of Diagnostic and Interventional Neuroradiology, Tuebingen (Germany); Krumm, Patrick; Schaefer, Juergen F.; Kramer, Ulrich [University Hospital of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Hornung, Andreas; Sieverding, Ludger [University Hospital of Tuebingen, Department of Pediatric Cardiology, Tuebingen (Germany)

    2015-09-15

    Newborns and small infants have shallow breathing. To suggest criteria for when respiratory gating is necessary during cardiac MRI in newborns and infants. One-hundred ten data sets of newborns and infants with (n = 92, mean age: 1.9 ± 1.7 [SD] years) and without (n = 18, mean age: 1.6 ± 1.8 [SD] years) navigator gating were analysed retrospectively. The respiratory motion of the right hemidiaphragm was recorded and correlated to age, weight, body surface area and qualitative image quality on a 4-point score. Quantitative image quality assessment was performed (sharpness of the delineation of the ventricular septal wall) as well as a matched-pair comparison between navigator-gated and non-gated data sets. No significant differences were found in overall image quality or in the sharpness of the ventricular septal wall between gated and non-gated scans. A navigator acceptance of >80% was frequently found in patients ages <12 months, body surface area <0.40 m{sup 2}, body weight <10 kg and a size of <80 cm. Sequences without respiratory gating may be used in newborns and small infants, in particular if age <12 months, body surface area <0.40 m{sup 2}, body weight <10 kg and height <80 cm. (orig.)

  7. SU-E-J-45: Design and Study of An In-House Respiratory Gating Phantom Platform for Gated Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Senthilkumar, S [Madurai Medical College ' Govt. Rajaji Hospital, Madurai (India)

    2014-06-01

    Purpose: The main purpose of this work was to develop an in-house low cost respiratory motion phantom platform for testing the accuracy of the gated radiotherapy system and analyze the dosimetric difference during gated radiotherapy. Methods: An in-house respiratory motion platform(RMP) was designed and constructed for testing the targeting accuracy of respiratory tracking system. The RMP consist of acrylic Chest Wall Platform, 2 DC motors, 4 IR sensors, speed controller circuit, 2 LED and 2 moving rods inside the RMP. The velocity of the movement can be varied from 0 to 30 cycles per minute. The platform mounted to a base using precision linear bearings. The base and platform are made of clear, 15mm thick polycarbonate plastic and the linear ball bearings are oriented to restrict the platform to a movement of approximately 50mm up and down with very little friction. Results: The targeting accuracy of the respiratory tracking system was evaluated using phantom with and without respiratory movement with varied amplitude. We have found the 5% dose difference to the PTV during the movement in comparison with stable PTV. The RMP can perform sinusoidal motion in 1D with fixed peak to peak motion of 5 to 50mm and cycle interval from 2 to 6 seconds. The RMP was designed to be able to simulate the gross anatomical anterior posterior motion attributable to respiration-induced motion of the thoracic region. Conclusion: The unique RMP simulates breathing providing the means to create a comprehensive program for commissioning, training, quality assurance and dose verification of gated radiotherapy treatments. Create the anterior/posterior movement of a target over a 5 to 50 mm distance to replicate tumor movement. The targeting error of the respiratory tracking system is less than 1.0 mm which shows suitable for clinical treatment with highly performance.

  8. SU-E-J-45: Design and Study of An In-House Respiratory Gating Phantom Platform for Gated Radiotherapy

    International Nuclear Information System (INIS)

    Senthilkumar, S

    2014-01-01

    Purpose: The main purpose of this work was to develop an in-house low cost respiratory motion phantom platform for testing the accuracy of the gated radiotherapy system and analyze the dosimetric difference during gated radiotherapy. Methods: An in-house respiratory motion platform(RMP) was designed and constructed for testing the targeting accuracy of respiratory tracking system. The RMP consist of acrylic Chest Wall Platform, 2 DC motors, 4 IR sensors, speed controller circuit, 2 LED and 2 moving rods inside the RMP. The velocity of the movement can be varied from 0 to 30 cycles per minute. The platform mounted to a base using precision linear bearings. The base and platform are made of clear, 15mm thick polycarbonate plastic and the linear ball bearings are oriented to restrict the platform to a movement of approximately 50mm up and down with very little friction. Results: The targeting accuracy of the respiratory tracking system was evaluated using phantom with and without respiratory movement with varied amplitude. We have found the 5% dose difference to the PTV during the movement in comparison with stable PTV. The RMP can perform sinusoidal motion in 1D with fixed peak to peak motion of 5 to 50mm and cycle interval from 2 to 6 seconds. The RMP was designed to be able to simulate the gross anatomical anterior posterior motion attributable to respiration-induced motion of the thoracic region. Conclusion: The unique RMP simulates breathing providing the means to create a comprehensive program for commissioning, training, quality assurance and dose verification of gated radiotherapy treatments. Create the anterior/posterior movement of a target over a 5 to 50 mm distance to replicate tumor movement. The targeting error of the respiratory tracking system is less than 1.0 mm which shows suitable for clinical treatment with highly performance

  9. Prospective Electrocardiogram-Gated Multidetector Row Computed Tomography Coronary Angiography. Analysis of Quality Image and Radiation Dose

    International Nuclear Information System (INIS)

    Carrascosa, P.; Capunay, C.; Deviggiano, A.; Tajer, C.D.; Vallejos, J.; Goldsmit, A.; Garcia, M.J.

    2009-01-01

    Multidetector row computed tomography coronary angiography (MDCT-CA) has become a useful diagnostic tool for the direct quantification of coronary stenosis, for identifying coronary anomalies and for the assessment of coronary artery bypass grafts. Despite its clinical value has been questioned due to the effective radiation dose (ERD) received by each patient, radiation exposure is similar to other studies. However, different strategies are permanently tested in order to reduce the ERD maintaining adequate and diagnostic image quality. Objectives: To determine the image quality and effective radiation dose (ERD) of prospective electrocardiogram-gated multidetector row computed tomography coronary angiography (PMDCTCA) (the x-ray beam is turned on for only a short portion of diastole) compared to retrospective ECG gating (RMDCTCA) (the x-ray beam is turned on throughout the cardiac cycle) and a preliminary approach of its diagnostic accuracy compared to digital invasive coronary angiography (CA). Material and Methods: Fifty consecutive patients with suspected coronary artery disease and sinus rhythm were evaluated with PMDCT-CA and compared to a control group who underwent RMDCTCA. Image quality was analyzed by two reviewers. Interobserver concordance and ERD were determined. The diagnostic accuracy of PMDCT-CA compared to CA to detect coronary artery stenosis > 50% was assessed in 30 patients. Results: There were no significant differences in the image quality between both groups. Agreement between the reviewers for segment image quality scores was k = 0.92. Mean ERD was 3.5 mSv for PMDCT-CA compared to 9.7 and 12.9 mSv for RMDCT-CA with and without tube current modulation, respectively. Individual analysis including all segments showed that the sensitivity, specificity, positive predictive value and negative predictive value of PMDCT-CA for the detection of coronary stenosis were 94.74%, 81.82%, 90% and 90%, respectively. Conclusion: Our initial experience

  10. Quality assurance for respiratory-gated stereotactic body radiation therapy in lung using real-time position management system

    International Nuclear Information System (INIS)

    Nakaguchi, Yuji; Maruyama, Masato; Araki, Fujio; Kouno, Tomohiro

    2012-01-01

    In this study, we investigated comprehensive quality assurance (QA) for respiratory-gated stereotactic body radiation therapy (SBRT) in the lungs using a real-time position management system (RPM). By using the phantom study, we evaluated dose liberality and reproducibility, and dose distributions for low monitor unite (MU), and also checked the absorbed dose at isocenter and dose profiles for the respiratory-gated exposure using RPM. Furthermore, we evaluated isocenter dose and dose distributions for respiratory-gated SBRT plans in the lungs using RPM. The maximum errors for the dose liberality were 4% for 2 MU, 1% for 4-10 MU, and 0.5% for 15 MU and 20 MU. The dose reproducibility was 2% for 1 MU and within 0.1% for 5 MU or greater. The accuracy for dose distributions was within 2% for 2 MU or greater. The dose error along a central axis for respiratory cycles of 2, 4, and 6 sec was within 1%. As for geometric accuracy, 90% and 50% isodose areas for the respiratory-gated exposure became almost 1 mm and 2 mm larger than without gating, respectively. For clinical lung-SBRT plans, the point dose at isocenter agreed within 2.1% with treatment planning system (TPS). And the pass rates of all plans for TPS were more than 96% in the gamma analysis (3 mm/3%). The geometrical accuracy and the dose accuracy of TPS calculation algorithm are more important for the dose evaluation at penumbra region for respiratory-gated SBRT in lung using RPM. (author)

  11. The relationship between coronary artery calcification detected by non-gated multi-detector CT in patients with suspected ischemic heart disease and myocardial ischemia detected by thallium exercise stress testing

    International Nuclear Information System (INIS)

    Nishida, Chikako; Okajima, Kaoru; Yamamoto, Takashi; Hattori, Ryuichi; Kudo, Takashi; Nishimura, Yasumasa

    2005-01-01

    The objective of this study was to examine whether we could predict myocardial ischemia when coronary artery calcification is detected by non-gated multidetector CT in patients with suspected ischemic heart disease. Eighty-three patients suspected of having ischemic heart disease (55 men, 28 women; age range 36-83 years; mean age 68 years) underwent multidetector CT and Tl-201 single photon emission computed tomography. Prediction of myocardial ischemia by coronary arterial calcification detected on CT was evaluated by comparing the coronary artery territories that showed calcification with the area of myocardial ischemia determined by SPECT. The sensitivity, specificity, positive predictive value, and negative predictive value of multidetector CT for predicting myocardial ischemia were calculated. Coronary angiography was also examined and compared with multidetector CT. Risk factors, including hypertension, smoking, hyperlipidemia, diabetes, and family history, were compared for evidence of coronary artery calcification detected by multidetector CT and myocardial ischemia detected by thallium nuclear scans. For analysis by patients, the sensitivity, specificity, positive predictive value, and negative predictive value of coronary artery calcification for myocardial ischemia detection were 65, 63, 56, and 71%, respectively. Similarly, for analysis by coronary arterial territories, those values were 56, 77, 41 and 86%, respectively. Coronary stenosis on CAG was also related to the ischemia determined by SPECT and calcification on multidetector CT. Ischemia was better influenced by risk factors than was coronary arterial calcification. For analysis by coronary arterial territories, the specificity and negative predictive value of coronary arterial calcification seen by multidetector CT are relatively high. (author)

  12. Feasibility of Systematic Respiratory-Gated Acquisition in Unselected Patients Referred for 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

    Directory of Open Access Journals (Sweden)

    Philippe Robin

    2018-02-01

    Full Text Available ObjectiveRespiratory motion in 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT induces blurred images, leading to errors in location and quantification for lung and abdominal lesions. Various methods have been developed to correct for these artifacts, and most of current PET/CT scanners are equipped with a respiratory gating system. However, they are not routinely performed because their use is time-consuming. The aim of this study is to assess the feasibility and quantitative impact of a systematic respiratory-gated acquisition in unselected patients referred for FDG PET/CT, without increasing acquisition time.MethodsPatients referred for a FDG PET/CT examination to the nuclear medicine department of Brest University Hospital were consecutively enrolled, during a 3-month period. Cases presenting lung or liver uptakes were analyzed. Two sets of images were reconstructed from data recorded during a unique acquisition with a continuous table speed of 1 mm/s of the used Biograph mCT Flow PET/CT scanner: standard free-breathing images, and respiratory-gated images. Lesion location and quantitative parameters were recorded and compared.ResultsFrom October 1 2015 to December 31 2015, 847 patients were referred for FDG PET/CT, 741 underwent a respiratory-gated acquisition. Out of them, 213 (29% had one or more lung or liver uptake but 82 (38% had no usable respiratory-gated signal. Accordingly, 131 (62% patients with 183 lung or liver uptakes were analyzed. Considering the 183 lesions, 140 and 43 were located in the lungs and the liver, respectively. The median (IQR difference between respiratory-gated images and non-gated images was 18% (4−32 for SUVmax, increasing to 30% (14−57 in lower lobes for lung lesions, and −18% (−40 to −4 for MTV (p < 0.05. Technologists’ active personal dosimetry and mean total examinations duration were not statistically different between periods with and without

  13. Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

    International Nuclear Information System (INIS)

    Bernatowicz, K.; Knopf, A.; Lomax, A.; Keall, P.; Kipritidis, J.; Mishra, P.

    2015-01-01

    Purpose: Prospective respiratory-gated 4D CT has been shown to reduce tumor image artifacts by up to 50% compared to conventional 4D CT. However, to date no studies have quantified the impact of gated 4D CT on normal lung tissue imaging, which is important in performing dose calculations based on accurate estimates of lung volume and structure. To determine the impact of gated 4D CT on thoracic image quality, the authors developed a novel simulation framework incorporating a realistic deformable digital phantom driven by patient tumor motion patterns. Based on this framework, the authors test the hypothesis that respiratory-gated 4D CT can significantly reduce lung imaging artifacts. Methods: Our simulation framework synchronizes the 4D extended cardiac torso (XCAT) phantom with tumor motion data in a quasi real-time fashion, allowing simulation of three 4D CT acquisition modes featuring different levels of respiratory feedback: (i) “conventional” 4D CT that uses a constant imaging and couch-shift frequency, (ii) “beam paused” 4D CT that interrupts imaging to avoid oversampling at a given couch position and respiratory phase, and (iii) “respiratory-gated” 4D CT that triggers acquisition only when the respiratory motion fulfills phase-specific displacement gating windows based on prescan breathing data. Our framework generates a set of ground truth comparators, representing the average XCAT anatomy during beam-on for each of ten respiratory phase bins. Based on this framework, the authors simulated conventional, beam-paused, and respiratory-gated 4D CT images using tumor motion patterns from seven lung cancer patients across 13 treatment fractions, with a simulated 5.5 cm 3 spherical lesion. Normal lung tissue image quality was quantified by comparing simulated and ground truth images in terms of overall mean square error (MSE) intensity difference, threshold-based lung volume error, and fractional false positive/false negative rates. Results: Averaged

  14. Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Bernatowicz, K., E-mail: kingab@student.ethz.ch; Knopf, A.; Lomax, A. [Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI 5232, Switzerland and Department of Physics, ETH Zürich, Zürich 8092 (Switzerland); Keall, P.; Kipritidis, J., E-mail: john.kipritidis@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, Sydney, NSW 2006 (Australia); Mishra, P. [Brigham and Womens Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States)

    2015-01-15

    Purpose: Prospective respiratory-gated 4D CT has been shown to reduce tumor image artifacts by up to 50% compared to conventional 4D CT. However, to date no studies have quantified the impact of gated 4D CT on normal lung tissue imaging, which is important in performing dose calculations based on accurate estimates of lung volume and structure. To determine the impact of gated 4D CT on thoracic image quality, the authors developed a novel simulation framework incorporating a realistic deformable digital phantom driven by patient tumor motion patterns. Based on this framework, the authors test the hypothesis that respiratory-gated 4D CT can significantly reduce lung imaging artifacts. Methods: Our simulation framework synchronizes the 4D extended cardiac torso (XCAT) phantom with tumor motion data in a quasi real-time fashion, allowing simulation of three 4D CT acquisition modes featuring different levels of respiratory feedback: (i) “conventional” 4D CT that uses a constant imaging and couch-shift frequency, (ii) “beam paused” 4D CT that interrupts imaging to avoid oversampling at a given couch position and respiratory phase, and (iii) “respiratory-gated” 4D CT that triggers acquisition only when the respiratory motion fulfills phase-specific displacement gating windows based on prescan breathing data. Our framework generates a set of ground truth comparators, representing the average XCAT anatomy during beam-on for each of ten respiratory phase bins. Based on this framework, the authors simulated conventional, beam-paused, and respiratory-gated 4D CT images using tumor motion patterns from seven lung cancer patients across 13 treatment fractions, with a simulated 5.5 cm{sup 3} spherical lesion. Normal lung tissue image quality was quantified by comparing simulated and ground truth images in terms of overall mean square error (MSE) intensity difference, threshold-based lung volume error, and fractional false positive/false negative rates. Results

  15. Improved method of in vivo respiratory-gated micro-CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Walters, Erin B; Panda, Kunal; Bankson, James A; Brown, Ellana; Cody, Dianna D [Department of Imaging Physics, Unit 56, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States)

    2004-09-07

    The presence of motion artifacts is a typical problem in thoracic imaging. However, synchronizing the respiratory cycle with computed tomography (CT) image acquisition can reduce these artifacts. We currently employ a method of in vivo respiratory-gated micro-CT imaging for small laboratory animals (mice). This procedure involves the use of a ventilator that controls the respiratory cycle of the animal and provides a digital output signal that is used to trigger data acquisition. After inspection of the default respiratory trigger timing, we hypothesized that image quality could be improved by moving the data-acquisition window to a portion of the cycle with less respiratory motion. For this reason, we developed a simple delay circuit to adjust the timing of the ventilator signal that initiates micro-CT data acquisition. This delay circuit decreases motion artifacts and substantially improves image quality.

  16. Improved method of in vivo respiratory-gated micro-CT imaging

    International Nuclear Information System (INIS)

    Walters, Erin B; Panda, Kunal; Bankson, James A; Brown, Ellana; Cody, Dianna D

    2004-01-01

    The presence of motion artifacts is a typical problem in thoracic imaging. However, synchronizing the respiratory cycle with computed tomography (CT) image acquisition can reduce these artifacts. We currently employ a method of in vivo respiratory-gated micro-CT imaging for small laboratory animals (mice). This procedure involves the use of a ventilator that controls the respiratory cycle of the animal and provides a digital output signal that is used to trigger data acquisition. After inspection of the default respiratory trigger timing, we hypothesized that image quality could be improved by moving the data-acquisition window to a portion of the cycle with less respiratory motion. For this reason, we developed a simple delay circuit to adjust the timing of the ventilator signal that initiates micro-CT data acquisition. This delay circuit decreases motion artifacts and substantially improves image quality

  17. Myocardial enhancement pattern in patients with acute myocardial infarction on two-phase contrast-enhanced Ecg-gated multidetector-row computed tomography

    International Nuclear Information System (INIS)

    Ko, S.M.; Seo, J.B.; Hong, M.K.; Do, K.H.; Lee, S.H.; Lee, J.S.; Song, J.W.; Park, S.J.; Park, S.W.; Lim, T.H.

    2006-01-01

    Aim: To evaluate the myocardial enhancement pattern of the left ventricle on two-phase contrast-enhanced electrocardiogram (ECG)-gated multidetector computed tomography (MDCT) images in patients with acute myocardial infarction (AMI). METHODS: Two-phase contrast-enhanced ECG-gated MDCT examinations were performed in 16 patients with AMI. The presence, location and pattern of myocardial enhancement were evaluated. MDCT findings were compared with the catheter angiographic results. RESULTS: Subendocardial (n=9) or transmural (n=6) area of early perfusion defects of the myocardium was detected in 15 of 16 patients (94%) on early-phase CT images. Variable delayed myocardial enhancement patterns on late-phase CT images were observed in 12 patients (75%): (1) subendocardial residual perfusion defect and subepicardial late enhancement (n=6); (2) transmural late enhancement (n=1); (3) isolated subendocardial late enhancement (n=1); and (4) isolated subendocardial residual perfusion defect (n=2). On catheter angiography, 14 of 15 corresponding coronary arteries showed significant stenosis. CONCLUSION: Variable abnormal myocardial enhancement pattern was seen on two-phase, contrast-enhanced ECG-gated MDCT in patients with AMI. Assessment of myocardial attenuation on CT angiography gives additional information of the location and extent of infarction

  18. MO-FG-BRA-08: Swarm Intelligence-Based Personalized Respiratory Gating in Lung SAbR

    Energy Technology Data Exchange (ETDEWEB)

    Modiri, A; Sabouri, P; Sawant, A [University of Maryland in Baltimore, Baltimore, MD (United States); Gu, X; Timmerman, R [University of Texas Southwestern Medical Center, Dallas, TX (United States)

    2016-06-15

    Purpose: Respiratory gating is widely deployed as a clinical motion-management strategy in lung radiotherapy. In conventional gating, the beam is turned on during a pre-determined phase window; typically, around end-exhalation. In this work, we challenge the notion that end-exhalation is always the optimal gating phase. Specifically, we use a swarm-intelligence-based, inverse planning approach to determine the optimal respiratory phase and MU for each beam with respect to (i) the state of the anatomy at each phase and (ii) the time spent in that state, estimated from long-term monitoring of the patient’s breathing motion. Methods: In a retrospective study of five lung cancer patients, we compared the dosimetric performance of our proposed personalized gating (PG) with that of conventional end-of-exhale gating (CEG) and a previously-developed, fully 4D-optimized plan (combined with MLC tracking delivery). For each patient, respiratory phase probabilities (indicative of the time duration of the phase) were estimated over 2 minutes from lung tumor motion traces recorded previously using the Synchrony system (Accuray Inc.). Based on this information, inverse planning optimization was performed to calculate the optimal respiratory gating phase and MU for each beam. To ensure practical deliverability, each PG beam was constrained to deliver the assigned MU over a time duration comparable to that of CEG delivery. Results: Maximum OAR sparing for the five patients achieved by the PG and the 4D plans compared to CEG plans was: Esophagus Dmax [PG:57%, 4D:37%], Heart Dmax [PG:71%, 4D:87%], Spinal cord Dmax [PG:18%, 4D:68%] and Lung V13 [PG:16%, 4D:31%]. While patients spent the most time in exhalation, the PG-optimization chose end-exhale only for 28% of beams. Conclusion: Our novel gating strategy achieved significant dosimetric improvements over conventional gating, and approached the upper limit represented by fully 4D optimized planning while being significantly simpler

  19. MO-FG-BRA-08: Swarm Intelligence-Based Personalized Respiratory Gating in Lung SAbR

    International Nuclear Information System (INIS)

    Modiri, A; Sabouri, P; Sawant, A; Gu, X; Timmerman, R

    2016-01-01

    Purpose: Respiratory gating is widely deployed as a clinical motion-management strategy in lung radiotherapy. In conventional gating, the beam is turned on during a pre-determined phase window; typically, around end-exhalation. In this work, we challenge the notion that end-exhalation is always the optimal gating phase. Specifically, we use a swarm-intelligence-based, inverse planning approach to determine the optimal respiratory phase and MU for each beam with respect to (i) the state of the anatomy at each phase and (ii) the time spent in that state, estimated from long-term monitoring of the patient’s breathing motion. Methods: In a retrospective study of five lung cancer patients, we compared the dosimetric performance of our proposed personalized gating (PG) with that of conventional end-of-exhale gating (CEG) and a previously-developed, fully 4D-optimized plan (combined with MLC tracking delivery). For each patient, respiratory phase probabilities (indicative of the time duration of the phase) were estimated over 2 minutes from lung tumor motion traces recorded previously using the Synchrony system (Accuray Inc.). Based on this information, inverse planning optimization was performed to calculate the optimal respiratory gating phase and MU for each beam. To ensure practical deliverability, each PG beam was constrained to deliver the assigned MU over a time duration comparable to that of CEG delivery. Results: Maximum OAR sparing for the five patients achieved by the PG and the 4D plans compared to CEG plans was: Esophagus Dmax [PG:57%, 4D:37%], Heart Dmax [PG:71%, 4D:87%], Spinal cord Dmax [PG:18%, 4D:68%] and Lung V13 [PG:16%, 4D:31%]. While patients spent the most time in exhalation, the PG-optimization chose end-exhale only for 28% of beams. Conclusion: Our novel gating strategy achieved significant dosimetric improvements over conventional gating, and approached the upper limit represented by fully 4D optimized planning while being significantly simpler

  20. An evaluation of gating window size, delivery method, and composite field dosimetry of respiratory-gated IMRT

    International Nuclear Information System (INIS)

    Hugo, Geoffrey D.; Agazaryan, Nzhde; Solberg, Timothy D.

    2002-01-01

    A respiratory gating system has been developed based on a commercial patient positioning system. The purpose of this study is to investigate the ability of the gating system to reproduce normal, nongated IMRT operation and to quantify the errors produced by delivering a nongated IMRT treatment onto a moving target. A moving phantom capable of simultaneous two-dimensional motion was built, and an analytical liver motion function was used to drive the phantom. Studies were performed to assess the effect of gating window size and choice of delivery method (segmented and dynamic multileaf collimation). Additionally, two multiple field IMRT cases were delivered to quantify the error in gated and nongated IMRT with motion. Dosimetric error between nonmoving and moving deliveries is related to gating window size. By reducing the window size, the error can be reduced. Delivery error can be reduced for both dynamic and segmented delivery with gating. For the implementation of dynamic IMRT delivery in this study, dynamic delivery was found to generate larger delivery errors than segmented delivery in most cases studied. For multiple field IMRT delivery, the largest errors were generated in regions where high field modulation was present parallel to the axis of motion. Gating was found to reduce these large errors to clinically acceptable levels

  1. Evaluation of the MEMS based portable respiratory training system with a tactile sensor for respiratory-gated radiotherapy

    Science.gov (United States)

    Moon, Sun Young; Yoon, Myonggeun; Chung, Mijoo; Chung, Weon Kuu; Kim, Dong Wook

    2017-10-01

    In respiratory-gated radiotherapy, it is important to maintain the regular respiratory cycles of patients. If patients undergo respiration training, their regular breathing pattern is affected. Therefore, we developed a respiratory training system based on a micro electromechanical system (MEMS) and evaluated the feasibility of the MEMS in radiotherapy. By comparing the measured signal before and after radiation exposure, we confirmed the effects of radiation. By evaluating the period of the electric signal emitted by a tactile sensor and its constancy, the performance of the tactile sensor was confirmed. Moreover, by comparing the delay between the motion of the MEMS and the electric signal from the tactile sensor, we confirmed the reaction time of the tactile sensor. The results showed that a baseline shift occurred for an accumulated dose of 400 Gy in the sensor, and both the amplitude and period changed. The period of the signal released by the tactile sensor was 5.39 and its standard deviation was 0.06. Considering the errors from the motion phantom, a standard deviation of 0.06 was desirable. The delay time was within 0.5 s and not distinguishable by a patient. We confirmed the performance of the MEMS and concluded that MEMS could be applied to patients for respiratory-gated radiotherapy.

  2. SU-E-J-89: Motion Effects On Organ Dose in Respiratory Gated Stereotactic Body Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T; Zhu, L [Georgia Institute of Technology, Atlanta, GA (Georgia); Khan, M; Landry, J; Rajpara, R; Hawk, N [Emory University, Atlanta, GA (United States)

    2014-06-01

    Purpose: Existing reports on gated radiation therapy focus mainly on optimizing dose delivery to the target structure. This work investigates the motion effects on radiation dose delivered to organs at risk (OAR) in respiratory gated stereotactic body radiation therapy (SBRT). A new algorithmic tool of dose analysis is developed to evaluate the optimality of gating phase for dose sparing on OARs while ensuring adequate target coverage. Methods: Eight patients with pancreatic cancer were treated on a phase I prospective study employing 4DCT-based SBRT. For each patient, 4DCT scans are acquired and sorted into 10 respiratory phases (inhale-exhale- inhale). Treatment planning is performed on the average CT image. The average CT is spatially registered to other phases. The resultant displacement field is then applied on the plan dose map to estimate the actual dose map for each phase. Dose values of each voxel are fitted to a sinusoidal function. Fitting parameters of dose variation, mean delivered dose and optimal gating phase for each voxel over respiration cycle are mapped on the dose volume. Results: The sinusoidal function accurately models the dose change during respiratory motion (mean fitting error 4.6%). In the eight patients, mean dose variation is 3.3 Gy on OARs with maximum of 13.7 Gy. Two patients have about 100cm{sup 3} volumes covered by more than 5 Gy deviation. The mean delivered dose maps are similar to plan dose with slight deformation. The optimal gating phase highly varies across the patient, with phase 5 or 6 on about 60% of the volume, and phase 0 on most of the rest. Conclusion: A new algorithmic tool is developed to conveniently quantify dose deviation on OARs from plan dose during the respiratory cycle. The proposed software facilitates the treatment planning process by providing the optimal respiratory gating phase for dose sparing on each OAR.

  3. Evaluation of respiratory movement during gated radiotherapy using film and electronic portal imaging

    International Nuclear Information System (INIS)

    Ford, E.C.; Mageras, G.S.; Yorke, E.; Rosenzweig, K.E.; Wagman, R.; Ling, C.C.

    2002-01-01

    Purpose: To evaluate the effectiveness of a commercial system in reducing respiration-induced treatment uncertainty by gating the radiation delivery. Methods and Materials: The gating system considered here measures respiration from the position of a reflective marker on the patient's chest. Respiration-triggered planning CT scans were obtained for 8 patients (4 lung, 4 liver) at the intended phase of respiration (6 at end expiration and 2 at end inspiration). In addition, fluoroscopic movies were recorded simultaneously with the respiratory waveform. During the treatment sessions, gated localization films were used to measure the position of the diaphragm relative to the vertebral bodies, which was compared to the reference digitally reconstructed radiograph derived from the respiration-triggered planning CT. Variability was quantified by the standard deviation about the mean position. We also assessed the interfraction variability of soft tissue structures during gated treatment in 2 patients using an amorphous silicon electronic portal imaging device. Results: The gated localization films revealed an interfraction patient-averaged diaphragm variability of 2.8±1.0 mm (error bars indicate standard deviation in the patient population). The fluoroscopic data yielded a patient-averaged intrafraction diaphragm variability of 2.6±1.7 mm. With no gating, this intrafraction excursion became 6.9±2.1 mm. In gated localization films, the patient-averaged mean displacement of the diaphragm from the planning position was 0.0±3.9 mm. However, in 4 of the 8 patients, the mean (over localization films) displacement was >4 mm, indicating a systematic displacement in treatment position from the planned one. The position of soft tissue features observed in portal images during gated treatments over several fractions showed a mean variability between 2.6 and 5.7 mm. The intrafraction variability, however, was between 0.6 and 1.4 mm, indicating that most of the variability was

  4. Correlation between the respiratory waveform measured using a respiratory sensor and 3D tumor motion in gated radiotherapy

    International Nuclear Information System (INIS)

    Tsunashima, Yoshikazu; Sakae, Takeji; Shioyama, Yoshiyuki; Kagei, Kenji; Terunuma, Toshiyuki; Nohtomi, Akihiro; Akine, Yasuyuki

    2004-01-01

    Purpose: The purpose of this study is to investigate the correlation between the respiratory waveform measured using a respiratory sensor and three-dimensional (3D) tumor motion. Methods and materials: A laser displacement sensor (LDS: KEYENCE LB-300) that measures distance using infrared light was used as the respiratory sensor. This was placed such that the focus was in an area around the patient's navel. When the distance from the LDS to the body surface changes as the patient breathes, the displacement is detected as a respiratory waveform. To obtain the 3D tumor motion, a biplane digital radiography unit was used. For the tumor in the lung, liver, and esophagus of 26 patients, the waveform was compared with the 3D tumor motion. The relationship between the respiratory waveform and the 3D tumor motion was analyzed by means of the Fourier transform and a cross-correlation function. Results: The respiratory waveform cycle agreed with that of the cranial-caudal and dorsal-ventral tumor motion. A phase shift observed between the respiratory waveform and the 3D tumor motion was principally in the range 0.0 to 0.3 s, regardless of the organ being measured, which means that the respiratory waveform does not always express the 3D tumor motion with fidelity. For this reason, the standard deviation of the tumor position in the expiration phase, as indicated by the respiratory waveform, was derived, which should be helpful in suggesting the internal margin required in the case of respiratory gated radiotherapy. Conclusion: Although obtained from only a few breathing cycles for each patient, the correlation between the respiratory waveform and the 3D tumor motion was evident in this study. If this relationship is analyzed carefully and an internal margin is applied, the accuracy and convenience of respiratory gated radiotherapy could be improved by use of the respiratory sensor.Thus, it is expected that this procedure will come into wider use

  5. Extraction of the respiratory signal from small-animal CT projections for a retrospective gating method

    Energy Technology Data Exchange (ETDEWEB)

    ChavarrIas, C; Vaquero, J J; Sisniega, A; RodrIguez-Ruano, A; Soto-Montenegro, M L; GarcIa-Barreno, P; Desco, M [Unidad de Medicina y CirugIa Experimental, Hospital General Universitario Gregorio Maranon, Anexo PsiquiatrIa, 1 Planta. C/Ibiza, 43. Madrid 28007 (Spain)

    2008-09-07

    We propose a retrospective respiratory gating algorithm to generate dynamic CT studies. To this end, we compared three different methods of extracting the respiratory signal from the projections of small-animal cone-beam computed tomography (CBCT) scanners. Given a set of frames acquired from a certain axial angle, subtraction of their average image from each individual frame produces a set of difference images. Pixels in these images have positive or negative values (according to the respiratory phase) in those areas where there is lung movement. The respiratory signals were extracted by analysing the shape of the histogram of these difference images: we calculated the first four central and non-central moments. However, only odd-order moments produced the desired breathing signal, as the even-order moments lacked information about the phase. Each of these curves was compared to a reference signal recorded by means of a pneumatic pillow. Given the similar correlation coefficients yielded by all of them, we selected the mean to implement our retrospective protocol. Respiratory phase bins were separated, reconstructed independently and included in a dynamic sequence, suitable for cine playback. We validated our method in five adult rat studies by comparing profiles drawn across the diaphragm dome, with and without retrospective respiratory gating. Results showed a sharper transition in the gated reconstruction, with an average slope improvement of 60.7%.

  6. Extraction of the respiratory signal from small-animal CT projections for a retrospective gating method

    International Nuclear Information System (INIS)

    ChavarrIas, C; Vaquero, J J; Sisniega, A; RodrIguez-Ruano, A; Soto-Montenegro, M L; GarcIa-Barreno, P; Desco, M

    2008-01-01

    We propose a retrospective respiratory gating algorithm to generate dynamic CT studies. To this end, we compared three different methods of extracting the respiratory signal from the projections of small-animal cone-beam computed tomography (CBCT) scanners. Given a set of frames acquired from a certain axial angle, subtraction of their average image from each individual frame produces a set of difference images. Pixels in these images have positive or negative values (according to the respiratory phase) in those areas where there is lung movement. The respiratory signals were extracted by analysing the shape of the histogram of these difference images: we calculated the first four central and non-central moments. However, only odd-order moments produced the desired breathing signal, as the even-order moments lacked information about the phase. Each of these curves was compared to a reference signal recorded by means of a pneumatic pillow. Given the similar correlation coefficients yielded by all of them, we selected the mean to implement our retrospective protocol. Respiratory phase bins were separated, reconstructed independently and included in a dynamic sequence, suitable for cine playback. We validated our method in five adult rat studies by comparing profiles drawn across the diaphragm dome, with and without retrospective respiratory gating. Results showed a sharper transition in the gated reconstruction, with an average slope improvement of 60.7%

  7. An automatic respiratory gating method for the improvement of microcirculation evaluation: application to contrast-enhanced ultrasound studies of focal liver lesions

    Energy Technology Data Exchange (ETDEWEB)

    Mule, S; Kachenoura, N; Lucidarme, O; De Oliveira, A; Pellot-Barakat, C; Herment, A; Frouin, F, E-mail: Sebastien.Mule@gmail.com [INSERM UMR-S 678, 75634 Paris Cedex 13 (France)

    2011-08-21

    Contrast-enhanced ultrasound (CEUS), with the recent development of both contrast-specific imaging modalities and microbubble-based contrast agents, allows noninvasive quantification of microcirculation in vivo. Nevertheless, functional parameters obtained by modeling contrast uptake kinetics could be impaired by respiratory motion. Accordingly, we developed an automatic respiratory gating method and tested it on 35 CEUS hepatic datasets with focal lesions. Each dataset included fundamental mode and cadence contrast pulse sequencing (CPS) mode sequences acquired simultaneously. The developed method consisted in (1) the estimation of the respiratory kinetics as a linear combination of the first components provided by a principal components analysis constrained by a prior knowledge on the respiratory rate in the frequency domain, (2) the automated generation of two respiratory-gated subsequences from the CPS mode sequence by detecting end-of-inspiration and end-of-expiration phases from the respiratory kinetics. The fundamental mode enabled a more reliable estimation of the respiratory kinetics than the CPS mode. The k-means algorithm was applied on both the original CPS mode sequences and the respiratory-gated subsequences resulting in clustering maps and associated mean kinetics. Our respiratory gating process allowed better superimposition of manually drawn lesion contours on k-means clustering maps as well as substantial improvement of the quality of contrast uptake kinetics. While the quality of maps and kinetics was satisfactory in only 11/35 datasets before gating, it was satisfactory in 34/35 datasets after gating. Moreover, noise amplitude estimated within the delineated lesions was reduced from 62 {+-} 21 to 40 {+-} 10 (p < 0.01) after gating. These findings were supported by the low residual horizontal (0.44 {+-} 0.29 mm) and vertical (0.15 {+-} 0.16 mm) shifts found during manual motion correction of each respiratory-gated subsequence. The developed

  8. Evaluation of respiratory and cardiac motion correction schemes in dual gated PET/CT cardiac imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lamare, F., E-mail: frederic.lamare@chu-bordeaux.fr; Fernandez, P. [Univ. Bordeaux, INCIA, UMR 5287, F-33400 Talence (France); CNRS, INCIA, UMR 5287, F-33400 Talence (France); Service de Médecine Nucléaire, Hôpital Pellegrin, CHU de Bordeaux, 33076 Bordeaux (France); Le Maitre, A.; Visvikis, D. [INSERM, UMR1101, LaTIM, Université de Bretagne Occidentale, 29609 Brest (France); Dawood, M.; Schäfers, K. P. [European Institute for Molecular Imaging, University of Münster, Mendelstr. 11, 48149 Münster (Germany); Rimoldi, O. E. [Vita-Salute University and Scientific Institute San Raffaele, Milan, Italy and CNR Istituto di Bioimmagini e Fisiologia Molecolare, Milan (Italy)

    2014-07-15

    Purpose: Cardiac imaging suffers from both respiratory and cardiac motion. One of the proposed solutions involves double gated acquisitions. Although such an approach may lead to both respiratory and cardiac motion compensation there are issues associated with (a) the combination of data from cardiac and respiratory motion bins, and (b) poor statistical quality images as a result of using only part of the acquired data. The main objective of this work was to evaluate different schemes of combining binned data in order to identify the best strategy to reconstruct motion free cardiac images from dual gated positron emission tomography (PET) acquisitions. Methods: A digital phantom study as well as seven human studies were used in this evaluation. PET data were acquired in list mode (LM). A real-time position management system and an electrocardiogram device were used to provide the respiratory and cardiac motion triggers registered within the LM file. Acquired data were subsequently binned considering four and six cardiac gates, or the diastole only in combination with eight respiratory amplitude gates. PET images were corrected for attenuation, but no randoms nor scatter corrections were included. Reconstructed images from each of the bins considered above were subsequently used in combination with an affine or an elastic registration algorithm to derive transformation parameters allowing the combination of all acquired data in a particular position in the cardiac and respiratory cycles. Images were assessed in terms of signal-to-noise ratio (SNR), contrast, image profile, coefficient-of-variation (COV), and relative difference of the recovered activity concentration. Results: Regardless of the considered motion compensation strategy, the nonrigid motion model performed better than the affine model, leading to higher SNR and contrast combined with a lower COV. Nevertheless, when compensating for respiration only, no statistically significant differences were

  9. Effectiveness of the Respiratory Gating System for Stereotectic Radiosurgery of Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Song, Heung Kwon; Kwon, Kyung Tae; Park, Cheol Su; Yang, Oh Nam; Kim, Min Su; Kim, Jeong Man [Dept. of Radiation Oncology, Asan Medical Center, Seoul (Korea, Republic of)

    2005-09-15

    For stereotactic radiosurgery (SRS) of a tumor in the region whose movement due to respiration is significant, like Lung lower lobe, the gated therapy, which delivers radiation dose to the selected respiratory phases when tumor motion is small, was performed using the Respiratory gating system and its clinical effectiveness was evaluated. For two SRS patients with a tumor in Lung lower lobe, a marker block (infrared reflector) was attached on the abdomen. While patient' respiratory cycle was monitored with Real-time Position Management (RPM, Varian, USA), 4D CT was performed (10 phases per a cycle). Phases in which tumor motion did not change rapidly were decided as treatment phases. The treatment volume was contoured on the CT images for selected treatment phases using maximum intensity projection (MIP) method. In order to verify setup reproducibility and positional variation, 4D CT was repeated. Gross tumor volume (GTV) showed maximum movement in superior-inferior direction. For patient no 1, motion of GTV was reduced to 2.6 mm in treatment phases (30-60%), while that was 9.4 mm in full phases (0-90%) and for patient no 2, it was reduced to 2.3 mm in treatment phases (30-70%), while it was 11.7 mm in full phases (0-90%). When comparing two sets of CT images, setup errors in all the directions were within 3 mm. Since tumor motion was reduced less than 5 mm, the Respiratory gating system for SRS of Lung lower lobe is useful.

  10. Feasibility study of multi-pass respiratory-gated helical tomotherapy of a moving target via binary MLC closure

    Science.gov (United States)

    Kim, Bryan; Chen, Jeff; Kron, Tomas; Battista, Jerry

    2010-11-01

    Gated radiotherapy of lung lesions is particularly complex for helical tomotherapy, due to the simultaneous motions of its three subsystems (gantry, couch and collimator). We propose a new way to implement gating for helical tomotherapy, namely multi-pass respiratory gating. In this method, gating is achieved by delivering only the beam projections that occur within a respiratory gating window, while blocking the rest of the beam projections by fully closing all collimator leaves. Due to the continuous couch motion, the planned beam projections must be delivered over multiple passes of radiation deliveries. After each pass, the patient couch is reset to its starting position, and the treatment recommences at a different phase of tumour motion to 'fill in' the previously blocked beam projections. The gating process may be repeated until the plan dose is delivered (full gating), or halted after a certain number of passes, with the entire remaining dose delivered in a final pass without gating (partial gating). The feasibility of the full gating approach was first tested for sinusoidal target motion, through experimental measurements with film and computer simulation. The optimal gating parameters for full and partial gating methods were then determined for various fractionation schemes through computer simulation, using a patient respiratory waveform. For sinusoidal motion, the PTV dose deviations of -29 to 5% observed without gating were reduced to range from -1 to 3% for a single fraction, with a 4 pass full gating. For a patient waveform, partial gating required fewer passes than full gating for all fractionation schemes. For a single fraction, the maximum allowed residual motion was only 4 mm, requiring large numbers of passes for both full (12) and partial (7 + 1) gating methods. The number of required passes decreased significantly for 3 and 30 fractions, allowing residual motion up to 7 mm. Overall, the multi-pass gating technique was shown to be a promising

  11. Feasibility study of multi-pass respiratory-gated helical tomotherapy of a moving target via binary MLC closure

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bryan; Chen, Jeff; Battista, Jerry [London Regional Cancer Program, London Health Sciences Centre, London, ON (Canada); Kron, Tomas, E-mail: bryan.kim@lhsc.on.c [Peter MacCallum Cancer Center, Melbourne (Australia)

    2010-11-21

    Gated radiotherapy of lung lesions is particularly complex for helical tomotherapy, due to the simultaneous motions of its three subsystems (gantry, couch and collimator). We propose a new way to implement gating for helical tomotherapy, namely multi-pass respiratory gating. In this method, gating is achieved by delivering only the beam projections that occur within a respiratory gating window, while blocking the rest of the beam projections by fully closing all collimator leaves. Due to the continuous couch motion, the planned beam projections must be delivered over multiple passes of radiation deliveries. After each pass, the patient couch is reset to its starting position, and the treatment recommences at a different phase of tumour motion to 'fill in' the previously blocked beam projections. The gating process may be repeated until the plan dose is delivered (full gating), or halted after a certain number of passes, with the entire remaining dose delivered in a final pass without gating (partial gating). The feasibility of the full gating approach was first tested for sinusoidal target motion, through experimental measurements with film and computer simulation. The optimal gating parameters for full and partial gating methods were then determined for various fractionation schemes through computer simulation, using a patient respiratory waveform. For sinusoidal motion, the PTV dose deviations of -29 to 5% observed without gating were reduced to range from -1 to 3% for a single fraction, with a 4 pass full gating. For a patient waveform, partial gating required fewer passes than full gating for all fractionation schemes. For a single fraction, the maximum allowed residual motion was only 4 mm, requiring large numbers of passes for both full (12) and partial (7 + 1) gating methods. The number of required passes decreased significantly for 3 and 30 fractions, allowing residual motion up to 7 mm. Overall, the multi-pass gating technique was shown to be a

  12. Detection of respiratory tumour motion using intrinsic list mode-driven gating in positron emission tomography.

    Science.gov (United States)

    Büther, Florian; Ernst, Iris; Dawood, Mohammad; Kraxner, Peter; Schäfers, Michael; Schober, Otmar; Schäfers, Klaus P

    2010-12-01

    Respiratory motion of organs during PET scans is known to degrade PET image quality, potentially resulting in blurred images, attenuation artefacts and erroneous tracer quantification. List mode-based gating has been shown to reduce these pitfalls in cardiac PET. This study evaluates these intrinsic gating methods for tumour PET scans. A total of 34 patients with liver or lung tumours (14 liver tumours and 27 lung tumours in all) underwent a 15-min single-bed list mode PET scan of the tumour region. Of these, 15 patients (8 liver and 11 lung tumours in total) were monitored by a video camera registering a marker on the patient's abdomen, thus capturing the respiratory motion for PET gating (video method). Further gating information was deduced by dividing the list mode stream into 200-ms frames, determining the number of coincidences (sensitivity method) and computing the axial centre of mass of the measured count rates in the same frames (centre of mass method). Additionally, these list mode-based methods were evaluated using only coincidences originating from the tumour region by segmenting the tumour in sinogram space (segmented sensitivity/centre of mass method). Measured displacement of the tumours between end-expiration and end-inspiration and the increase in apparent uptake in the gated images served as a measure for the exactness of gating. To estimate the accuracy, a thorax phantom study with moved activity sources simulating small tumours was also performed. All methods resolved the respiratory motion with varying success. The best results were seen in the segmented centre of mass method, on average leading to larger displacements and uptake values than the other methods. The simple centre of mass method performed worse in terms of displacements due to activities moving into the field of view during the respiratory cycle. Both sensitivity- and video-based methods lead to similar results. List mode-driven PET gating, especially the segmented centre of mass

  13. Utility estimation of the application of auditory-visual-tactile sense feedback in respiratory gated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Jung Hun; KIm, Byeong Jin; Roh, Shi Won; Lee, Hyeon Chan; Jang, Hyeong Jun; Kim, Hoi Nam [Dept. of Radiation Oncology, Biomedical Engineering, Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Song, Jae Hoon [Dept. of Biomedical Engineering, Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Kim, Young Jae [Dept. of Radiological Technology, Gwang Yang Health Collage, Gwangyang (Korea, Republic of)

    2013-03-15

    The purpose of this study was to evaluate the possibility to optimize the gated treatment delivery time and maintenance of stable respiratory by the introduction of breath with the assistance of auditory-visual-tactile sense. The experimenter's respiration were measured by ANZAI 4D system. We obtained natural breathing signal, monitor-induced breathing signal, monitor and ventilator-induced breathing signal, and breath-hold signal using real time monitor during 10 minutes beam-on-time. In order to check the stability of respiratory signals distributed in each group were compared with means, standard deviation, variation value, beam{sub t}ime of the respiratory signal. The stability of each respiratory was measured in consideration of deviation change studied in each respiratory time lapse. As a result of an analysis of respiratory signal, all experimenters has showed that breathing signal used both Real time monitor and Ventilator was the most stable and shortest time. In this study, it was evaluated that respiratory gated radiation therapy with auditory-visual-tactual sense and without auditory-visual-tactual sense feedback. The study showed that respiratory gated radiation therapy delivery time could significantly be improved by the application of video feedback when this is combined with audio-tactual sense assistance. This delivery technique did prove its feasibility to limit the tumor motion during treatment delivery for all patients to a defined value while maintaining the accuracy and proved the applicability of the technique in a conventional clinical schedule.

  14. Utility estimation of the application of auditory-visual-tactile sense feedback in respiratory gated radiation therapy

    International Nuclear Information System (INIS)

    Jo, Jung Hun; KIm, Byeong Jin; Roh, Shi Won; Lee, Hyeon Chan; Jang, Hyeong Jun; Kim, Hoi Nam; Song, Jae Hoon; Kim, Young Jae

    2013-01-01

    The purpose of this study was to evaluate the possibility to optimize the gated treatment delivery time and maintenance of stable respiratory by the introduction of breath with the assistance of auditory-visual-tactile sense. The experimenter's respiration were measured by ANZAI 4D system. We obtained natural breathing signal, monitor-induced breathing signal, monitor and ventilator-induced breathing signal, and breath-hold signal using real time monitor during 10 minutes beam-on-time. In order to check the stability of respiratory signals distributed in each group were compared with means, standard deviation, variation value, beam t ime of the respiratory signal. The stability of each respiratory was measured in consideration of deviation change studied in each respiratory time lapse. As a result of an analysis of respiratory signal, all experimenters has showed that breathing signal used both Real time monitor and Ventilator was the most stable and shortest time. In this study, it was evaluated that respiratory gated radiation therapy with auditory-visual-tactual sense and without auditory-visual-tactual sense feedback. The study showed that respiratory gated radiation therapy delivery time could significantly be improved by the application of video feedback when this is combined with audio-tactual sense assistance. This delivery technique did prove its feasibility to limit the tumor motion during treatment delivery for all patients to a defined value while maintaining the accuracy and proved the applicability of the technique in a conventional clinical schedule

  15. Technical and dosimetric aspects of respiratory gating using a pressure-sensor motion monitoring system

    International Nuclear Information System (INIS)

    Li, X. Allen; Stepaniak, Christopher; Gore, Elizabeth

    2006-01-01

    This work introduces a gating technique that uses 4DCT to determine gating parameters and to plan gated treatment, and employs a Siemens linear accelerator to deliver the gated treatment. Because of technology incompatibility, the 4DCT scanner (LightSpeed, GE) and the Siemens accelerator require two different motion-monitoring systems. The motion monitoring system (AZ-773V, Anzai Med.) used for the gated delivery utilizes a pressure sensor to detect the external respiratory motion (pressure change) in real time. Another system (RPM, Varian) used for the 4DCT scanner (LightSpeed, GE) is based on an infrared camera to detect motion of external markers. These two motion monitoring systems (RPM and Anzai systems) were found to correlate well with each other. The depth doses and profile measured for gated delivery (with a duty cycle of 25% or 50%) were found to agree within 1.0% with those measured for ungated delivery, indicating that gating did not significantly alter beam characteristics. The measurement verified also that the MU linearity and beam output remained unchanged (within 0.3%). A practical method of using 4DCT to plan a gated treatment was developed. The duty cycle for either phase or amplitude gating can be determined based on 4DCT with consideration of set-up error and delivery efficiency. The close-loop measurement involving the entire gating process (imaging, planning, and delivery) showed that the measured isodose distributions agreed with those intended, validating the accuracy and reliability of the gating technique. Based these observations, we conclude that the gating technique introduced in this work, integrating Siemens linear accelerator and Anzai pressure sensor device with GE/Varian RPM 4DCT, is reliable and effective, and it can be used clinically to account for respiratory motion during radiation therapy

  16. Audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI

    Science.gov (United States)

    Lee, D.; Greer, P. B.; Arm, J.; Keall, P.; Kim, T.

    2014-03-01

    The purpose of this study was to test the hypothesis that audiovisual (AV) biofeedback can improve image quality and reduce scan time for respiratory-gated 3D thoracic MRI. For five healthy human subjects respiratory motion guidance in MR scans was provided using an AV biofeedback system, utilizing real-time respiratory motion signals. To investigate the improvement of respiratory-gated 3D MR images between free breathing (FB) and AV biofeedback (AV), each subject underwent two imaging sessions. Respiratory-related motion artifacts and imaging time were qualitatively evaluated in addition to the reproducibility of external (abdominal) motion. In the results, 3D MR images in AV biofeedback showed more anatomic information such as a clear distinction of diaphragm, lung lobes and sharper organ boundaries. The scan time was reduced from 401±215 s in FB to 334±94 s in AV (p-value 0.36). The root mean square variation of the displacement and period of the abdominal motion was reduced from 0.4±0.22 cm and 2.8±2.5 s in FB to 0.1±0.15 cm and 0.9±1.3 s in AV (p-value of displacement audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI. These results suggest that AV biofeedback has the potential to be a useful motion management tool in medical imaging and radiation therapy procedures.

  17. Assessment of regional lung functional impairment with co-registered respiratory-gated ventilation/perfusion SPET-CT images: initial experiences

    International Nuclear Information System (INIS)

    Suga, Kazuyoshi; Yasuhiko, Kawakami; Zaki, Mohammed; Yamashita, Tomio; Seto, Aska; Matsumoto, Tsuneo; Matsunaga, Naofumi

    2004-01-01

    In this study, respiratory-gated ventilation and perfusion single-photon emission tomography (SPET) were used to define regional functional impairment and to obtain reliable co-registration with computed tomography (CT) images in various lung diseases. Using a triple-headed SPET unit and a physiological synchroniser, gated perfusion SPET was performed in a total of 78 patients with different pulmonary diseases, including metastatic nodules (n=15); in 34 of these patients, it was performed in combination with gated technetium-99m Technegas SPET. Projection data were acquired using 60 stops over 120 for each detector. Gated end-inspiration and ungated images were reconstructed from 1/8 data centered at peak inspiration for each regular respiratory cycle and full respiratory cycle data, respectively. Gated images were registered with tidal inspiration CT images using automated three-dimensional (3D) registration software. Registration mismatch was assessed by measuring 3D distance of the centroid of the nine selected round perfusion-defective nodules. Gated SPET images were completed within 29 min, and increased the number of visible ventilation and perfusion defects by 9.7% and 17.2%, respectively, as compared with ungated images; furthermore, lesion-to-normal lung contrast was significantly higher on gated SPET images. In the nine round perfusion-defective nodules, gated images yielded a significantly better SPET-CT match compared with ungated images (4.9±3.1 mm vs 19.0±9.1 mm, P<0.001). The co-registered SPET-CT images allowed accurate perception of the location and extent of each ventilation/perfusion defect on the underlying CT anatomy, and characterised the pathophysiology of the various diseases. By reducing respiratory motion effects and enhancing perfusion/ventilation defect clarity, gated SPET can provide reliable co-registered images with CT images to accurately characterise regional functional impairment in various lung diseases. (orig.)

  18. Respiratory gated radiotherapy-pretreatment patient specific quality assurance

    Directory of Open Access Journals (Sweden)

    Rajesh Thiyagarajan

    2016-01-01

    Full Text Available Organ motions during inter-fraction and intra-fraction radiotherapy introduce errors in dose delivery, irradiating excess of normal tissue, and missing target volume. Lung and heart involuntary motions cause above inaccuracies and gated dose delivery try to overcome above effects. Present work attempts a novel method to verify dynamic dose delivery using a four-dimensional (4D phantom. Three patients with mobile target are coached to maintain regular and reproducible breathing pattern. Appropriate intensity projection image set generated from 4D-computed tomography (4D-CT is used for target delineation. Intensity modulated radiotherapy plans were generated on selected phase using CT simulator (Siemens AG, Germany in conjunction with "Real-time position management" (Varian, USA to acquire 4D-CT images. Verification plans were generated for both ion chamber and Gafchromic (EBT film image sets. Gated verification plans were delivered on the phantom moving with patient respiratory pattern. We developed a MATLAB-based software to generate maximum intensity projection, minimum intensity projections, and average intensity projections, also a program to convert patient breathing pattern to phantom compatible format. Dynamic thorax quality assurance (QA phantom (Computerized Imaging Reference Systems type is used to perform the patient specific QA, which holds an ion chamber and film to measure delivered radiation intensity. Exposed EBT films are analyzed and compared with treatment planning system calculated dose. The ion chamber measured dose shows good agreement with planned dose within ± 0.5% (0.203 ± 0.57%. Gamma value evaluated from EBT film shows passing rates 92–99% (96.63 ± 3.84% for 3% dose and 3 mm distance criteria. Respiratory gated treatment delivery accuracy is found to be within clinically acceptable level.

  19. Impact of a new respiratory amplitude-based gating technique in evaluation of upper abdominal PET lesions

    Energy Technology Data Exchange (ETDEWEB)

    Van Der Gucht, Axel, E-mail: axel.vandergucht@gmail.com [Department of Nuclear Medicine, Centre Hospitalier Princesse Grace, Monaco (Monaco); Serrano, Benjamin [Department of Medical Physics, Centre Hospitalier Princesse Grace, Monaco (Monaco); Hugonnet, Florent; Paulmier, Benoît [Department of Nuclear Medicine, Centre Hospitalier Princesse Grace, Monaco (Monaco); Garnier, Nicolas [Department of Medical Physics, Centre Hospitalier Princesse Grace, Monaco (Monaco); Faraggi, Marc [Department of Nuclear Medicine, Centre Hospitalier Princesse Grace, Monaco (Monaco)

    2014-03-15

    PET acquisition requires several minutes which can lead to respiratory motion blurring, to increase partial volume effect and SUV under-estimation. To avoid these artifacts, conventional 10-min phase-based respiratory gating (PBRG) can be performed but is time-consuming and difficult with a non-compliant patient. We evaluated an automatic amplitude-based gating method (AABG) which keeps 35% of the counts at the end of expiration to minimize respiratory motion. We estimated the impact of AABG on upper abdominal lesion detectability, quantification and patient management. Methods: We consecutively included 31 patients (82 hepatic and 25 perihepatic known lesions). Each patient underwent 3 acquisitions on a Siemens Biograph mCT (4 rings and time-of-flight): a standard free-breathing whole-body (SWB, 5–7 steps/2.5 min per step, 3.3 ± 0.4 MBq/kg of 18F-FDG), a 10-min PBRG with six bins and a 5-min AABG method. All gated acquisitions were performed with an ANZAI respiratory gating system. SUV{sub max} and target to background ratio (TBR, defined as the maximum SUV of the lesion divided by the mean SUV of a region of interest drawn in healthy liver) were compared. Results: All 94 lesions in SWB images were detected in the gated images. 10-min PBRG and 5-min AABG acquisitions respectively revealed 9 and 13 new lesions and relocated 7 and 8 lesions. Four lesions revealed by 5-min AABG were missed by 10-min PBRG in 3 non-compliant patients. Both gated methods failed to relocate 2 lesions seen on SWB acquisition. Compared to SWB, TBR increased significantly with 10-min PBRG and with 5-min AABG (respectively 41 ± 59%, p = 4.10–3 and 66 ± 75%, p = 6.10–5) whereas SUV{sub max} did not (respectively 14 ± 43%, p = 0.29 with 10-min PBRG, and 24 ± 46%, p = 0.11 with 5-min AABG). Conclusion: The AABG is a fast and a user-friendly respiratory gating method to increase detectability and quantification of upper abdominal lesions compared to the conventional PBRG procedure and

  20. A radial sampling strategy for uniform k-space coverage with retrospective respiratory gating in 3D ultrashort-echo-time lung imaging.

    Science.gov (United States)

    Park, Jinil; Shin, Taehoon; Yoon, Soon Ho; Goo, Jin Mo; Park, Jang-Yeon

    2016-05-01

    The purpose of this work was to develop a 3D radial-sampling strategy which maintains uniform k-space sample density after retrospective respiratory gating, and demonstrate its feasibility in free-breathing ultrashort-echo-time lung MRI. A multi-shot, interleaved 3D radial sampling function was designed by segmenting a single-shot trajectory of projection views such that each interleaf samples k-space in an incoherent fashion. An optimal segmentation factor for the interleaved acquisition was derived based on an approximate model of respiratory patterns such that radial interleaves are evenly accepted during the retrospective gating. The optimality of the proposed sampling scheme was tested by numerical simulations and phantom experiments using human respiratory waveforms. Retrospectively, respiratory-gated, free-breathing lung MRI with the proposed sampling strategy was performed in healthy subjects. The simulation yielded the most uniform k-space sample density with the optimal segmentation factor, as evidenced by the smallest standard deviation of the number of neighboring samples as well as minimal side-lobe energy in the point spread function. The optimality of the proposed scheme was also confirmed by minimal image artifacts in phantom images. Human lung images showed that the proposed sampling scheme significantly reduced streak and ring artifacts compared with the conventional retrospective respiratory gating while suppressing motion-related blurring compared with full sampling without respiratory gating. In conclusion, the proposed 3D radial-sampling scheme can effectively suppress the image artifacts due to non-uniform k-space sample density in retrospectively respiratory-gated lung MRI by uniformly distributing gated radial views across the k-space. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Reproducibility of image quality for moving objects using respiratory-gated computed tomography. A study using a phantom model

    International Nuclear Information System (INIS)

    Fukumitsu, Nobuyoshi; Ishida, Masaya; Terunuma, Toshiyuki

    2012-01-01

    To investigate the reproducibility of computed tomography (CT) imaging quality in respiratory-gated radiation treatment planning is essential in radiotherapy of movable tumors. Seven series of regular and six series of irregular respiratory motions were performed using a thorax dynamic phantom. For the regular respiratory motions, the respiratory cycle was changed from 2.5 to 4 s and the amplitude was changed from 4 to 10 mm. For the irregular respiratory motions, a cycle of 2.5 to 4 or an amplitude of 4 to 10 mm was added to the base data (id est (i.e.) 3.5-s cycle, 6-mm amplitude) every three cycles. Images of the object were acquired six times using respiratory-gated data acquisition. The volume of the object was calculated and the reproducibility of the volume was decided based on the variety. The registered image of the object was added and the reproducibility of the shape was decided based on the degree of overlap of objects. The variety in the volumes and shapes differed significantly as the respiratory cycle changed according to regular respiratory motions. In irregular respiratory motion, shape reproducibility was further inferior, and the percentage of overlap among the six images was 35.26% in the 2.5- and 3.5-s cycle mixed group. Amplitude changes did not produce significant differences in the variety of the volumes and shapes. Respiratory cycle changes reduced the reproducibility of the image quality in respiratory-gated CT. (author)

  2. SPECT acquisition using dynamic projections: a novel approach for data-driven respiratory gating

    International Nuclear Information System (INIS)

    Hutton, B.F.; Hatton, R.L.; Yip, N.

    2002-01-01

    Full text: Movement of the heart due to respiration has been previously demonstrated to produce potentially serious artefacts. On-line respiratory gating is difficult, as it requires a high level of patient cooperation. We demonstrate that use of dynamic acquisition of projections permits identification of the respiratory dynamics, allowing retrospective selection of data corresponding to a fixed point in the respiratory cycle. To demonstrate the feasibility of the technique a dynamic study was acquired just prior to myocardial per-fusion SPECT acquisition, using 5 frames/sec for 20 seconds (64*64 matrix) in anterior and lateral projections (using a dual-head right-angled configuration). The dynamic was processed a) by compressing frames in the transverse direction so as to illustrate time dependence, b) by plotting the centre of mass in the axial direction as a function of time. Respiratory motion was enhanced by use of temporal smoothing and intensity thresholding. In ten patients studied the cyclic pattern of motion due to respiratory dynamics was clearly visible in nine. Respiration typically resulted in around 1cm axial translation but in some individuals, movements as large as 3 cm were identified. The respiration rate ranged from 12-18 /min in agreement with independent observation of the patient's breathing pattern. These results suggest that retrospective respiratory gating is feasible without the need for any external respiratory monitoring device, provide that dynamic acquisition of SPECT projections is implemented. Correction for respiratory motion may also be feasible using this technique. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  3. Amplitude-based optimal respiratory gating in positron emission tomography in patients with primary lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Grootjans, Willem; Meeuwis, Antoi P.W.; Vos, Charlotte S. van der; Gotthardt, Martin; Oyen, Wim J.G.; Visser, Eric P. [Radboud University Medical Center, Department of Radiology and Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Geus-Oei, Lioe-Fee de [Radboud University Medical Center, Department of Radiology and Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); University of Twente, MIRA Institute for Biomedical Technology and Technical Medicine, Enschede (Netherlands)

    2014-12-15

    Respiratory motion during PET imaging introduces quantitative and diagnostic inaccuracies, which may result in non-optimal patient management. This study investigated the effects of respiratory gating on image quantification using an amplitude-based optimal respiratory gating (ORG) algorithm. Whole body FDG-PET/CT was performed in 66 lung cancer patients. The respiratory signal was obtained using a pressure sensor integrated in an elastic belt placed around the patient's thorax. ORG images were reconstructed with 50 %, 35 %, and 20 % of acquired PET data (duty cycle). Lesions were grouped into anatomical locations. Differences in lesion volume between ORG and non-gated images, and mean FDG-uptake (SUV{sub mean}) were calculated. Lesions in the middle and lower lobes demonstrated a significant SUV{sub mean} increase for all duty cycles and volume decrease for duty cycles of 35 % and 20 %. Significant increase in SUV{sub mean} and decrease in volume for lesions in the upper lobes were observed for a 20 % duty cycle. The SUV{sub mean} increase for central lesions was significant for all duty cycles, whereas a significant volume decrease was observed for a duty cycle of 20 %. This study implies that ORG could influence clinical PET imaging with respect to response monitoring and radiotherapy planning. (orig.)

  4. Audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI

    International Nuclear Information System (INIS)

    Lee, D; Keall, P; Kim, T; Greer, P B; Arm, J

    2014-01-01

    The purpose of this study was to test the hypothesis that audiovisual (AV) biofeedback can improve image quality and reduce scan time for respiratory-gated 3D thoracic MRI. For five healthy human subjects respiratory motion guidance in MR scans was provided using an AV biofeedback system, utilizing real-time respiratory motion signals. To investigate the improvement of respiratory-gated 3D MR images between free breathing (FB) and AV biofeedback (AV), each subject underwent two imaging sessions. Respiratory-related motion artifacts and imaging time were qualitatively evaluated in addition to the reproducibility of external (abdominal) motion. In the results, 3D MR images in AV biofeedback showed more anatomic information such as a clear distinction of diaphragm, lung lobes and sharper organ boundaries. The scan time was reduced from 401±215 s in FB to 334±94 s in AV (p-value 0.36). The root mean square variation of the displacement and period of the abdominal motion was reduced from 0.4±0.22 cm and 2.8±2.5 s in FB to 0.1±0.15 cm and 0.9±1.3 s in AV (p-value of displacement <0.01 and p-value of period 0.12). This study demonstrated that audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI. These results suggest that AV biofeedback has the potential to be a useful motion management tool in medical imaging and radiation therapy procedures.

  5. Automatic intrinsic cardiac and respiratory gating from cone-beam CT scans of the thorax region

    Science.gov (United States)

    Hahn, Andreas; Sauppe, Sebastian; Lell, Michael; Kachelrieß, Marc

    2016-03-01

    We present a new algorithm that allows for raw data-based automated cardiac and respiratory intrinsic gating in cone-beam CT scans. It can be summarized in three steps: First, a median filter is applied to an initially reconstructed volume. The forward projection of this volume contains less motion information and is subtracted from the original projections. This results in new raw data that contain only moving and not static anatomy like bones, that would otherwise impede the cardiac or respiratory signal acquisition. All further steps are applied to these modified raw data. Second, the raw data are cropped to a region of interest (ROI). The ROI in the raw data is determined by the forward projection of a binary volume of interest (VOI) that includes the diaphragm for respiratory gating and most of the edge of the heart for cardiac gating. Third, the mean gray value in this ROI is calculated for every projection and the respiratory/cardiac signal is acquired using a bandpass filter. Steps two and three are carried out simultaneously for 64 or 1440 overlapping VOI inside the body for the respiratory or cardiac signal respectively. The signals acquired from each ROI are compared and the most consistent one is chosen as the desired cardiac or respiratory motion signal. Consistency is assessed by the standard deviation of the time between two maxima. The robustness and efficiency of the method is evaluated using simulated and measured patient data by computing the standard deviation of the mean signal difference between the ground truth and the intrinsic signal.

  6. Real-time system for respiratory-cardiac gating in positron tomography

    International Nuclear Information System (INIS)

    Klein, G.J.; Reutter, B.W.; Ho, M.H.; Huesman, R.H.; Reed, J.H.

    1998-01-01

    A Macintosh-based signal processing system has been developed to support simultaneous respiratory and cardiac gating on the ECAT EXACT HR PET scanner. Using the Lab-View real-time software environment, the system reads analog inputs from a pneumatic respiratory bellows and an EGG monitor to compute an appropriate histogram memory location for the PET data. Respiratory state is determined by the bellows signal amplitude; cardiac state is based on the time since the last R-wave. These two states are used in a 2D lookup table to determine a combined respiratory-cardiac state. A 4-bit address encoding the selected histogram is directed from the system to the ECAT scanner, which dynamically switches the destination of tomograph events as respiratory-cardiac state changes. to Test the switching efficiency of the combined Macintosh/ECAT system, a rotating emission phantom was built. Acquisitions with 25 msec states while the phantom was rotating at 240 rpm demonstrate the system could effectively stop motion at this rate, with approximately 5 msec switching time between states

  7. Residual Motion and Duty Time in Respiratory Gating Radiotherapy Using Individualized or Population-Based Windows

    International Nuclear Information System (INIS)

    Fuji, Hiroshi; Asada, Yoshihiro; Numano, Masumi; Yamashita, Haruo; Nishimura, Tetsuo; Hashimoto, Takayuki; Harada, Hideyuki; Asakura, Hirofumi; Murayama, Shigeyuki

    2009-01-01

    Purpose: The efficiency and precision of respiratory gated radiation therapy for tumors is affected by variations in respiration-induced tumor motion. We evaluated the use of individualized and population-based parameters for such treatment. Methods and Materials: External respiratory signal records and images of respiration-induced tumor motion were obtained from 42 patients undergoing respiratory gated radiation therapy for liver tumors. Gating window widths were calculated for each patient, with 2, 4, and 10 mm of residual motion, and the mean was defined as the population-based window width. Residual motions based on population-based and predefined window widths were compared. Duty times based on whole treatment sessions, at various window levels, were calculated. The window level giving the longest duty time was defined as the individualized most efficient level (MEL). MELs were also calculated based on the first 10 breathing cycles. The duty times for population-based MELs (defined as mean MELs) and individualized MELs were compared. Results: Tracks of respiration-induced tumor motion ranged from 3 to 50 mm. Half of the patients had larger actual residual motions than the assigned residual motions. Duty times were greater when based on individualized, rather than population-based, window widths. The MELs established during whole treatment sessions for 2 mm and 4 mm of residual motion gave significantly increased duty times, whereas those calculated using the first 10 breathing cycles showed only marginal increases. Conclusions: Using individualized window widths and levels provided more precise and efficient respiratory gated radiation therapy. However, methods for predicting individualized window levels before treatment remain to be explored.

  8. Improved attenuation correction for respiratory gated PET/CT with extended-duration cine CT: a simulation study

    Science.gov (United States)

    Zhang, Ruoqiao; Alessio, Adam M.; Pierce, Larry A.; Byrd, Darrin W.; Lee, Tzu-Cheng; De Man, Bruno; Kinahan, Paul E.

    2017-03-01

    Due to the wide variability of intra-patient respiratory motion patterns, traditional short-duration cine CT used in respiratory gated PET/CT may be insufficient to match the PET scan data, resulting in suboptimal attenuation correction that eventually compromises the PET quantitative accuracy. Thus, extending the duration of cine CT can be beneficial to address this data mismatch issue. In this work, we propose to use a long-duration cine CT for respiratory gated PET/CT, whose cine acquisition time is ten times longer than a traditional short-duration cine CT. We compare the proposed long-duration cine CT with the traditional short-duration cine CT through numerous phantom simulations with 11 respiratory traces measured during patient PET/CT scans. Experimental results show that, the long-duration cine CT reduces the motion mismatch between PET and CT by 41% and improves the overall reconstruction accuracy by 42% on average, as compared to the traditional short-duration cine CT. The long-duration cine CT also reduces artifacts in PET images caused by misalignment and mismatch between adjacent slices in phase-gated CT images. The improvement in motion matching between PET and CT by extending the cine duration depends on the patient, with potentially greater benefits for patients with irregular breathing patterns or larger diaphragm movements.

  9. Effectiveness of respiratory-gated radiotherapy with audio-visual biofeedback for synchrotron-based scanned heavy-ion beam delivery

    Science.gov (United States)

    He, Pengbo; Li, Qiang; Zhao, Ting; Liu, Xinguo; Dai, Zhongying; Ma, Yuanyuan

    2016-12-01

    A synchrotron-based heavy-ion accelerator operates in pulse mode at a low repetition rate that is comparable to a patient’s breathing rate. To overcome inefficiencies and interplay effects between the residual motion of the target and the scanned heavy-ion beam delivery process for conventional free breathing (FB)-based gating therapy, a novel respiratory guidance method was developed to help patients synchronize their breathing patterns with the synchrotron excitation patterns by performing short breath holds with the aid of personalized audio-visual biofeedback (BFB) system. The purpose of this study was to evaluate the treatment precision, efficiency and reproducibility of the respiratory guidance method in scanned heavy-ion beam delivery mode. Using 96 breathing traces from eight healthy volunteers who were asked to breathe freely and guided to perform short breath holds with the aid of BFB, a series of dedicated four-dimensional dose calculations (4DDC) were performed on a geometric model which was developed assuming a linear relationship between external surrogate and internal tumor motions. The outcome of the 4DDCs was quantified in terms of the treatment time, dose-volume histograms (DVH) and dose homogeneity index. Our results show that with the respiratory guidance method the treatment efficiency increased by a factor of 2.23-3.94 compared with FB gating, depending on the duty cycle settings. The magnitude of dose inhomogeneity for the respiratory guidance methods was 7.5 times less than that of the non-gated irradiation, and good reproducibility of breathing guidance among different fractions was achieved. Thus, our study indicates that the respiratory guidance method not only improved the overall treatment efficiency of respiratory-gated scanned heavy-ion beam delivery, but also had the advantages of lower dose uncertainty and better reproducibility among fractions.

  10. SU-G-JeP1-08: Dual Modality Verification for Respiratory Gating Using New Real- Time Tumor Tracking Radiotherapy System

    Energy Technology Data Exchange (ETDEWEB)

    Shiinoki, T; Hanazawa, H; Shibuya, K [Yamaguchi University, Ube, Yamaguchi (Japan); Kawamura, S; Koike, M; Yuasa, Y; Uehara, T; Fujimoto, K [Yamaguchi University Hospital, Ube, Yamaguchi (Japan)

    2016-06-15

    Purpose: The respirato ry gating system combined the TrueBeam and a new real-time tumor-tracking radiotherapy system (RTRT) was installed. The RTRT system consists of two x-ray tubes and color image intensifiers. Using fluoroscopic images, the fiducial marker which was implanted near the tumor was tracked and was used as the internal surrogate for respiratory gating. The purposes of this study was to develop the verification technique of the respiratory gating with the new RTRT using cine electronic portal image device images (EPIDs) of TrueBeam and log files of the RTRT. Methods: A patient who underwent respiratory gated SBRT of the lung using the RTRT were enrolled in this study. For a patient, the log files of three-dimensional coordinate of fiducial marker used as an internal surrogate were acquired using the RTRT. Simultaneously, the cine EPIDs were acquired during respiratory gated radiotherapy. The data acquisition was performed for one field at five sessions during the course of SBRT. The residual motion errors were calculated using the log files (E{sub log}). The fiducial marker used as an internal surrogate into the cine EPIDs was automatically extracted by in-house software based on the template-matching algorithm. The differences between the the marker positions of cine EPIDs and digitally reconstructed radiograph were calculated (E{sub EPID}). Results: Marker detection on EPID using in-house software was influenced by low image contrast. For one field during the course of SBRT, the respiratory gating using the RTRT showed the mean ± S.D. of 95{sup th} percentile E{sub EPID} were 1.3 ± 0.3 mm,1.1 ± 0.5 mm,and those of E{sub log} were 1.5 ± 0.2 mm, 1.1 ± 0.2 mm in LR and SI directions, respectively. Conclusion: We have developed the verification method of respiratory gating combined TrueBeam and new real-time tumor-tracking radiotherapy system using EPIDs and log files.

  11. Optimization of a retrospective technique for respiratory-gated high speed micro-CT of free-breathing rodents

    International Nuclear Information System (INIS)

    Ford, Nancy L; Wheatley, Andrew R; Holdsworth, David W; Drangova, Maria

    2007-01-01

    The objective of this study was to develop a technique for dynamic respiratory imaging using retrospectively gated high-speed micro-CT imaging of free-breathing mice. Free-breathing C57Bl6 mice were scanned using a dynamic micro-CT scanner, comprising a flat-panel detector mounted on a slip-ring gantry. Projection images were acquired over ten complete gantry rotations in 50 s, while monitoring the respiratory motion in synchrony with projection-image acquisition. Projection images belonging to a selected respiratory phase were retrospectively identified and used for 3D reconstruction. The effect of using fewer gantry rotations-which influences both image quality and the ability to quantify respiratory function-was evaluated. Images reconstructed using unique projections from six or more gantry rotations produced acceptable images for quantitative analysis of lung volume, CT density, functional residual capacity and tidal volume. The functional residual capacity (0.15 ± 0.03 mL) and tidal volumes (0.08 ± 0.03 mL) measured in this study agree with previously reported measurements made using prospectively gated micro-CT and at higher resolution (150 μm versus 90 μm voxel spacing). Retrospectively gated micro-CT imaging of free-breathing mice enables quantitative dynamic measurement of morphological and functional parameters in the mouse models of respiratory disease, with scan times as short as 30 s, based on the acquisition of projection images over six gantry rotations

  12. Optimization of a retrospective technique for respiratory-gated high speed micro-CT of free-breathing rodents

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Nancy L [Department of Physics, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Wheatley, Andrew R [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada); Holdsworth, David W [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada); Drangova, Maria [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada)

    2007-09-21

    The objective of this study was to develop a technique for dynamic respiratory imaging using retrospectively gated high-speed micro-CT imaging of free-breathing mice. Free-breathing C57Bl6 mice were scanned using a dynamic micro-CT scanner, comprising a flat-panel detector mounted on a slip-ring gantry. Projection images were acquired over ten complete gantry rotations in 50 s, while monitoring the respiratory motion in synchrony with projection-image acquisition. Projection images belonging to a selected respiratory phase were retrospectively identified and used for 3D reconstruction. The effect of using fewer gantry rotations-which influences both image quality and the ability to quantify respiratory function-was evaluated. Images reconstructed using unique projections from six or more gantry rotations produced acceptable images for quantitative analysis of lung volume, CT density, functional residual capacity and tidal volume. The functional residual capacity (0.15 {+-} 0.03 mL) and tidal volumes (0.08 {+-} 0.03 mL) measured in this study agree with previously reported measurements made using prospectively gated micro-CT and at higher resolution (150 {mu}m versus 90 {mu}m voxel spacing). Retrospectively gated micro-CT imaging of free-breathing mice enables quantitative dynamic measurement of morphological and functional parameters in the mouse models of respiratory disease, with scan times as short as 30 s, based on the acquisition of projection images over six gantry rotations.

  13. Evaluation of irradiation position in respiratory-gated radiotherapy using a phantom system simulating patient respiration

    International Nuclear Information System (INIS)

    Oyama, Masaya; Ueda, Takashi; Kitoh, Satoshi; Tanaka, Takashi; Goka, Tomonori; Ogino, Takashi

    2006-01-01

    Respiratory-gated (RG) radiotherapy is useful for minimizing the irradiated volume of normal tissues resulting from the shifting of internal structures caused by respiratory movement. The present study was conducted to evaluate the treatment field in RG radiotherapy using a phantom system simulating patient respiration. A phantom system consisting of a 3-cm ball-shaped dummy tumor and film placed in a cork lung phantom was used (THK Co., Ltd.). RG radiotherapy was employed in the expiratory phase. The phantom movement distance was set to 2 cm, and the gating signals from a respiratory-gating system (AZ-733V, Anzai Medical) were varied. The settings used for irradiation were an X-ray energy of 6 MV (PRIMUS, Toshiba Medical Systems), treatment field of 5 cm x 7 cm, and X-ray dose of 100 MU. Images were acquired using an electric portal-imaging device (EPID, OPTIVUE 500), and the X-ray dose distribution was measured by the film method. In images acquired using the EPID, the tumor margins became less clear when the gating signals were increased, and the ITVs were determined to be 3.6 cm, 3.7 cm, 4.2 cm, and 5.1 cm at gating rates of 10%, 25%, 50%, and no gate, respectively. With regard to the X-ray dose distribution measured by the film method, the dose profile in the cephalocaudal direction was shifted toward the expiratory phase, and the degree of shift became greater when the gating signals were increased. In addition, the optimal treatment fields in the cephalocaudal direction were determined to be 5.2 cm, 5.2 cm, 5.6 cm, and 7.0 cm at gating rates of 10%, 25%, 50%, and no gating, respectively. Although RG radiotherapy is useful for improving the accuracy of radiotherapy, the characteristics of the RG radiotherapy technique and the radiotherapy system must be clearly understood when this method is to be employed in clinical practice. Image-guided radiotherapy (IGRT) is now assuming a central role in radiotherapy, and properly identifying internal margins is an

  14. Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema

    Science.gov (United States)

    Ford, N. L.; Martin, E. L.; Lewis, J. F.; Veldhuizen, R. A. W.; Holdsworth, D. W.; Drangova, M.

    2009-04-01

    Non-invasive micro-CT imaging techniques have been developed to investigate lung structure in free-breathing rodents. In this study, we investigate the utility of retrospectively respiratory-gated micro-CT imaging in an emphysema model to determine if anatomical changes could be observed in the image-derived quantitative analysis at two respiratory phases. The emphysema model chosen was a well-characterized, genetically altered model (TIMP-3 knockout mice) that exhibits a homogeneous phenotype. Micro-CT scans of the free-breathing, anaesthetized mice were obtained in 50 s and retrospectively respiratory sorted and reconstructed, providing 3D images representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Anatomical measurements included the volume and CT density of the lungs and the volume of the major airways, along with the diameters of the trachea, left bronchus and right bronchus. From these measurements, functional parameters such as functional residual capacity and tidal volume were calculated. Significant differences between the wild-type and TIMP-3 knockout groups were observed for measurements of CT density over the entire lung, indicating increased air content in the lungs of TIMP-3 knockout mice. These results demonstrate retrospective respiratory-gated micro-CT, providing images at multiple respiratory phases that can be analyzed quantitatively to investigate anatomical changes in murine models of emphysema.

  15. Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema

    International Nuclear Information System (INIS)

    Ford, N L; Martin, E L; Lewis, J F; Veldhuizen, R A W; Holdsworth, D W; Drangova, M

    2009-01-01

    Non-invasive micro-CT imaging techniques have been developed to investigate lung structure in free-breathing rodents. In this study, we investigate the utility of retrospectively respiratory-gated micro-CT imaging in an emphysema model to determine if anatomical changes could be observed in the image-derived quantitative analysis at two respiratory phases. The emphysema model chosen was a well-characterized, genetically altered model (TIMP-3 knockout mice) that exhibits a homogeneous phenotype. Micro-CT scans of the free-breathing, anaesthetized mice were obtained in 50 s and retrospectively respiratory sorted and reconstructed, providing 3D images representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Anatomical measurements included the volume and CT density of the lungs and the volume of the major airways, along with the diameters of the trachea, left bronchus and right bronchus. From these measurements, functional parameters such as functional residual capacity and tidal volume were calculated. Significant differences between the wild-type and TIMP-3 knockout groups were observed for measurements of CT density over the entire lung, indicating increased air content in the lungs of TIMP-3 knockout mice. These results demonstrate retrospective respiratory-gated micro-CT, providing images at multiple respiratory phases that can be analyzed quantitatively to investigate anatomical changes in murine models of emphysema.

  16. Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema

    Energy Technology Data Exchange (ETDEWEB)

    Ford, N L [Department of Physics, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Martin, E L; Lewis, J F; Veldhuizen, R A W [Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2 (Canada); Holdsworth, D W; Drangova, M [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada)], E-mail: nlford@ryerson.ca

    2009-04-07

    Non-invasive micro-CT imaging techniques have been developed to investigate lung structure in free-breathing rodents. In this study, we investigate the utility of retrospectively respiratory-gated micro-CT imaging in an emphysema model to determine if anatomical changes could be observed in the image-derived quantitative analysis at two respiratory phases. The emphysema model chosen was a well-characterized, genetically altered model (TIMP-3 knockout mice) that exhibits a homogeneous phenotype. Micro-CT scans of the free-breathing, anaesthetized mice were obtained in 50 s and retrospectively respiratory sorted and reconstructed, providing 3D images representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Anatomical measurements included the volume and CT density of the lungs and the volume of the major airways, along with the diameters of the trachea, left bronchus and right bronchus. From these measurements, functional parameters such as functional residual capacity and tidal volume were calculated. Significant differences between the wild-type and TIMP-3 knockout groups were observed for measurements of CT density over the entire lung, indicating increased air content in the lungs of TIMP-3 knockout mice. These results demonstrate retrospective respiratory-gated micro-CT, providing images at multiple respiratory phases that can be analyzed quantitatively to investigate anatomical changes in murine models of emphysema.

  17. A contactless approach for respiratory gating in PET using continuous-wave radar.

    Science.gov (United States)

    Ersepke, Thomas; Büther, Florian; Heß, Mirco; Schäfers, Klaus P

    2015-08-01

    Respiratory gating is commonly used to reduce motion artifacts in positron emission tomography (PET). Clinically established methods for respiratory gating in PET require contact to the patient or a direct optical line between the sensor and the patient's torso and time consuming preparation. In this work, a contactless method for capturing a respiratory signal during PET is presented based on continuous-wave radar. The proposed method relies on the principle of emitting an electromagnetic wave and detecting the phase shift of the reflected wave, modulated due to the respiratory movement of the patient's torso. A 24 GHz carrier frequency was chosen allowing wave propagation through plastic and clothing with high reflections at the skin surface. A detector module and signal processing algorithms were developed to extract a quantitative respiratory signal. The sensor was validated using a high precision linear table. During volunteer measurements and [(18)F] FDG PET scans, the radar sensor was positioned inside the scanner bore of a PET/computed tomography scanner. As reference, pressure belt (one volunteer), depth camera-based (two volunteers, two patients), and PET data-driven (six patients) signals were acquired simultaneously and the signal correlation was quantified. The developed system demonstrated a high measurement accuracy for movement detection within the submillimeter range. With the proposed method, small displacements of 25 μm could be detected, not considerably influenced by clothing or blankets. From the patient studies, the extracted respiratory radar signals revealed high correlation (Pearson correlation coefficient) to those derived from the external pressure belt and depth camera signals (r = 0.69-0.99) and moderate correlation to those of the internal data-driven signals (r = 0.53-0.70). In some cases, a cardiac signal could be visualized, due to the representation of the mechanical heart motion on the skin. Accurate respiratory signals were

  18. Development of patient-controlled respiratory gating system based on visual guidance for magnetic-resonance image-guided radiation therapy.

    Science.gov (United States)

    Kim, Jung-In; Lee, Hanyoung; Wu, Hong-Gyun; Chie, Eui Kyu; Kang, Hyun-Cheol; Park, Jong Min

    2017-09-01

    The aim of this study is to develop a visual guidance patient-controlled (VG-PC) respiratory gating system for respiratory-gated magnetic-resonance image-guided radiation therapy (MR-IGRT) and to evaluate the performance of the developed system. The near-real-time cine planar MR image of a patient acquired during treatment was transmitted to a beam projector in the treatment room through an optical fiber cable. The beam projector projected the cine MR images inside the bore of the ViewRay system in order to be visible to a patient during treatment. With this visual information, patients voluntarily controlled their respiration to put the target volume into the gating boundary (gating window). The effect of the presence of the beam projector in the treatment room on the image quality of the MRI was investigated by evaluating the signal-to-noise ratio (SNR), uniformity, low-contrast detectability, high-contrast spatial resolution, and spatial integrity with the VG-PC gating system. To evaluate the performance of the developed system, we applied the VG-PC gating system to a total of seven patients; six patients received stereotactic ablative radiotherapy (SABR) and one patient received conventional fractionated radiation therapy. The projected cine MR images were visible even when the room light was on. No image data loss or additional time delay during delivery of image data were observed. Every indicator representing MRI quality, including SNR, uniformity, low-contrast detectability, high-contrast spatial resolution, and spatial integrity exhibited values higher than the tolerance levels of the manufacturer with the VG-PC gating system; therefore, the presence of the VG-PC gating system in the treatment room did not degrade the MR image quality. The average beam-off times due to respiratory gating with and without the VG-PC gating system were 830.3 ± 278.2 s and 1264.2 ± 302.1 s respectively (P = 0.005). Consequently, the total treatment times excluding

  19. Clinical application of MRI-respiratory gating technology in the evaluation of children with obstructive sleep apnea hypopnea syndrome.

    Science.gov (United States)

    Zeng, Guohui; Teng, Yaoshu; Zhu, Jin; Zhu, Darong; Yang, Bin; Hu, Linping; Chen, Manman; Fu, Xiao

    2018-01-01

    The objective of the present study was to investigate the clinical application of magnetic resonance imaging (MRI)-respiratory gating technology for assessing illness severity in children with obstructive sleep apnea hypopnea syndrome (OSAHS).MRI-respiratory gating technology was used to scan the nasopharyngeal cavities of 51 children diagnosed with OSAHS during 6 respiratory phases. Correlations between the ratio of the area of the adenoid to the area of the nasopalatine pharyngeal cavity (Sa/Snp), with the main indexes of polysomnography (PSG), were analyzed. Receiver operator characteristic (ROC) curve and Kappa analysis were used to determine the diagnostic accuracy of Sa/Snp in pediatric OSAHS.The Sa/Snp was positively correlated with the apnea hypopnea index (AHI) (P children. Consistency analysis with the AHI showed a diagnosis accordance rate of 96.0% in severe pediatric OSAHS and 96.2% in slight-moderate pediatric OSAHS (Kappa = 0.922, P children with adenoidal hypertrophy was greatest at the end-expiration phase during sleep. The end-expiratory Sa/Snp obtained by a combination of MRI and respiratory gating technology has potential as an important imaging index for diagnosing and evaluating severity in pediatric OSAHS.

  20. Validation of a gating technique for radiotherapy treatment of injuries affected by respiratory motion; Validacion de una atecnica de gating para el tratamiento con radioterapia externa de lesiones afectadas por el movimiento respiratorio

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Ortega, J.; Castro Tejero, P.

    2011-07-01

    The use of gating techniques for the treatment of lesions that are involved respiratory motion may bring an increase in the dose administered. tumors and decreased the dose to adjacent healthy organs. In the study presented shows the steps taken to validate the respiratory gating technique using the RPM system (Real-time Position Management) from Varian. (Author)

  1. Respiratory-Gated MRgHIFU in Upper Abdomen Using an MR-Compatible In-Bore Digital Camera

    Directory of Open Access Journals (Sweden)

    Vincent Auboiroux

    2014-01-01

    Full Text Available Objective. To demonstrate the technical feasibility and the potential interest of using a digital optical camera inside the MR magnet bore for monitoring the breathing cycle and subsequently gating the PRFS MR thermometry, MR-ARFI measurement, and MRgHIFU sonication in the upper abdomen. Materials and Methods. A digital camera was reengineered to remove its magnetic parts and was further equipped with a 7 m long USB cable. The system was electromagnetically shielded and operated inside the bore of a closed 3T clinical scanner. Suitable triggers were generated based on real-time motion analysis of the images produced by the camera (resolution 640×480 pixels, 30 fps. Respiratory-gated MR-ARFI prepared MRgHIFU ablation was performed in the kidney and liver of two sheep in vivo, under general anaesthesia and ventilator-driven forced breathing. Results. The optical device demonstrated very good MR compatibility. The current setup permitted the acquisition of motion artefact-free and high resolution MR 2D ARFI and multiplanar interleaved PRFS thermometry (average SNR 30 in liver and 56 in kidney. Microscopic histology indicated precise focal lesions with sharply delineated margins following the respiratory-gated HIFU sonications. Conclusion. The proof-of-concept for respiratory motion management in MRgHIFU using an in-bore digital camera has been validated in vivo.

  2. Implementation of respiratory-gated VMAT on a Versa HD linear accelerator.

    Science.gov (United States)

    Snyder, Jeffrey E; Flynn, Ryan T; Hyer, Daniel E

    2017-09-01

    The accurate delivery of respiratory-gated volumetric modulated arc therapy (VMAT) treatment plans presents a challenge since the gantry rotation and collimator leaves must be repeatedly stopped and set into motion during each breathing cycle. In this study, we present the commissioning process for an Anzai gating system (AZ-733VI) on an Elekta Versa HD linear accelerator and make recommendations for successful clinical implementation. The commissioning tests include central axis dose consistency, profile consistency, gating beam-on/off delay, and comparison of gated versus nongated gamma pass rates for patient-specific quality assurance using four clinically commissioned photon energies: 6 MV, 6 FFF, 10 MV, and 10 FFF. The central axis dose constancy between gated and nongated deliveries was within 0.6% for all energies and the analysis of open field profiles for gated and nongated deliveries showed an agreement of 97.8% or greater when evaluated with a percent difference criteria of 1%. The measurement of the beam-on/off delay was done by evaluating images of a moving ball-bearing phantom triggered by the gating system and average beam-on delays of 0.22-0.29 s were observed. No measurable beam-off delay was present. Measurements of gated VMAT dose distributions resulted in decrements as high as 9% in the gamma passing rate as compared to nongated deliveries when evaluated against the planned dose distribution at 3%/3 mm. By decreasing the dose rate, which decreases the gantry speed during gated delivery, the gamma passing rates of gated and nongated treatments can be made equivalent. We present an empirically derived formula to limit the maximum dose rate during VMAT deliveries and show that by implementing a reduced dose rate, a gamma passing rate of greater than 95% (3%/3 mm) was obtained for all plan measurements. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of

  3. Real-time prediction and gating of respiratory motion using an extended Kalman filter and Gaussian process regression

    International Nuclear Information System (INIS)

    Bukhari, W; Hong, S-M

    2015-01-01

    Motion-adaptive radiotherapy aims to deliver a conformal dose to the target tumour with minimal normal tissue exposure by compensating for tumour motion in real time. The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of the treatment beam due to respiratory motion. In this article, we present a real-time algorithm for predicting and gating respiratory motion that utilizes a model-based and a model-free Bayesian framework by combining them in a cascade structure. The algorithm, named EKF-GPR + , implements a gating function without pre-specifying a particular region of the patient’s breathing cycle. The algorithm first employs an extended Kalman filter (LCM-EKF) to predict the respiratory motion and then uses a model-free Gaussian process regression (GPR) to correct the error of the LCM-EKF prediction. The GPR is a non-parametric Bayesian algorithm that yields predictive variance under Gaussian assumptions. The EKF-GPR + algorithm utilizes the predictive variance from the GPR component to capture the uncertainty in the LCM-EKF prediction error and systematically identify breathing points with a higher probability of large prediction error in advance. This identification allows us to pause the treatment beam over such instances. EKF-GPR + implements the gating function by using simple calculations based on the predictive variance with no additional detection mechanism. A sparse approximation of the GPR algorithm is employed to realize EKF-GPR + in real time. Extensive numerical experiments are performed based on a large database of 304 respiratory motion traces to evaluate EKF-GPR + . The experimental results show that the EKF-GPR + algorithm effectively reduces the prediction error in a root-mean-square (RMS) sense by employing the gating function, albeit at the cost of a reduced duty cycle. As an example, EKF-GPR + reduces the patient-wise RMS error to 37%, 39% and 42

  4. Real-time prediction and gating of respiratory motion using an extended Kalman filter and Gaussian process regression

    Science.gov (United States)

    Bukhari, W.; Hong, S.-M.

    2015-01-01

    Motion-adaptive radiotherapy aims to deliver a conformal dose to the target tumour with minimal normal tissue exposure by compensating for tumour motion in real time. The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of the treatment beam due to respiratory motion. In this article, we present a real-time algorithm for predicting and gating respiratory motion that utilizes a model-based and a model-free Bayesian framework by combining them in a cascade structure. The algorithm, named EKF-GPR+, implements a gating function without pre-specifying a particular region of the patient’s breathing cycle. The algorithm first employs an extended Kalman filter (LCM-EKF) to predict the respiratory motion and then uses a model-free Gaussian process regression (GPR) to correct the error of the LCM-EKF prediction. The GPR is a non-parametric Bayesian algorithm that yields predictive variance under Gaussian assumptions. The EKF-GPR+ algorithm utilizes the predictive variance from the GPR component to capture the uncertainty in the LCM-EKF prediction error and systematically identify breathing points with a higher probability of large prediction error in advance. This identification allows us to pause the treatment beam over such instances. EKF-GPR+ implements the gating function by using simple calculations based on the predictive variance with no additional detection mechanism. A sparse approximation of the GPR algorithm is employed to realize EKF-GPR+ in real time. Extensive numerical experiments are performed based on a large database of 304 respiratory motion traces to evaluate EKF-GPR+. The experimental results show that the EKF-GPR+ algorithm effectively reduces the prediction error in a root-mean-square (RMS) sense by employing the gating function, albeit at the cost of a reduced duty cycle. As an example, EKF-GPR+ reduces the patient-wise RMS error to 37%, 39% and 42% in

  5. Real-time prediction and gating of respiratory motion using an extended Kalman filter and Gaussian process regression.

    Science.gov (United States)

    Bukhari, W; Hong, S-M

    2015-01-07

    Motion-adaptive radiotherapy aims to deliver a conformal dose to the target tumour with minimal normal tissue exposure by compensating for tumour motion in real time. The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of the treatment beam due to respiratory motion. In this article, we present a real-time algorithm for predicting and gating respiratory motion that utilizes a model-based and a model-free Bayesian framework by combining them in a cascade structure. The algorithm, named EKF-GPR(+), implements a gating function without pre-specifying a particular region of the patient's breathing cycle. The algorithm first employs an extended Kalman filter (LCM-EKF) to predict the respiratory motion and then uses a model-free Gaussian process regression (GPR) to correct the error of the LCM-EKF prediction. The GPR is a non-parametric Bayesian algorithm that yields predictive variance under Gaussian assumptions. The EKF-GPR(+) algorithm utilizes the predictive variance from the GPR component to capture the uncertainty in the LCM-EKF prediction error and systematically identify breathing points with a higher probability of large prediction error in advance. This identification allows us to pause the treatment beam over such instances. EKF-GPR(+) implements the gating function by using simple calculations based on the predictive variance with no additional detection mechanism. A sparse approximation of the GPR algorithm is employed to realize EKF-GPR(+) in real time. Extensive numerical experiments are performed based on a large database of 304 respiratory motion traces to evaluate EKF-GPR(+). The experimental results show that the EKF-GPR(+) algorithm effectively reduces the prediction error in a root-mean-square (RMS) sense by employing the gating function, albeit at the cost of a reduced duty cycle. As an example, EKF-GPR(+) reduces the patient-wise RMS error to 37%, 39% and

  6. Evaluation of the Usefulness of the Respiratory Guidance System in the Respiratory Gating Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yeong Cheol; Kim, Sun Myung; Do, Gyeong Min; Park, Geun Yong; Kim, Gun Oh; Kim, Young Bum [Dept. of Radiation Oncology, Guro Hospital, Korea Univeristy, Seoul (Korea, Republic of)

    2012-09-15

    The respiration is one of the most important factors in respiratory gating radiation therapy (RGRT). We have developed an unique respiratory guidance system using an audio-visual system in order to support and stabilize individual patient's respiration and evaluated the usefulness of this system. Seven patients received the RGRT at our clinic from June 2011 to April 2012. After breathing exercise standard deviations by the superficial contents of respiratory cycles and functions, and analyzed them to examine changes in their breathing before and with the audio-visual system, we measured their spontaneous respiration and their respiration with the audio-visual system respectively. With the measured data, we yielded after the therapy. The PTP (peak to peak) of the standard deviations of the free breathing, the audio guidance system, and the respiratory guidance system were 0.343, 0.148, and 0.078 respectively. The respiratory cycles were 0.645, 0.345, and 0.171 respectively and the superficial contents of the respiratory functions were 2.591, 1.008, and 0.877 respectively. The average values of the differences in the standard deviations among the whole patients at the CT room and therapy room were 0.425 for the PTP, 1.566 for the respiratory cycles, and 3.671 for the respiratory superficial contents. As for the standard deviations before and after the application of the PTP respiratory guidance system, that of the PTP was 0.265, that of the respiratory cycles was 0.474, and that of the respiratory superficial contents. The results of t-test of the values before and after free breathing and the audio-visual guidance system showed that the P-value of the PTP was 0.035, that of the cycles 0.009, and that of the respiratory superficial contents 0.010. The respiratory control could be one of the most important factors in the RGRT which determines the success or failure of a treatment. We were able to get more stable breathing with the audio-visual respiratory

  7. Evaluation of the Usefulness of the Respiratory Guidance System in the Respiratory Gating Radiation Therapy

    International Nuclear Information System (INIS)

    Lee, Yeong Cheol; Kim, Sun Myung; Do, Gyeong Min; Park, Geun Yong; Kim, Gun Oh; Kim, Young Bum

    2012-01-01

    The respiration is one of the most important factors in respiratory gating radiation therapy (RGRT). We have developed an unique respiratory guidance system using an audio-visual system in order to support and stabilize individual patient's respiration and evaluated the usefulness of this system. Seven patients received the RGRT at our clinic from June 2011 to April 2012. After breathing exercise standard deviations by the superficial contents of respiratory cycles and functions, and analyzed them to examine changes in their breathing before and with the audio-visual system, we measured their spontaneous respiration and their respiration with the audio-visual system respectively. With the measured data, we yielded after the therapy. The PTP (peak to peak) of the standard deviations of the free breathing, the audio guidance system, and the respiratory guidance system were 0.343, 0.148, and 0.078 respectively. The respiratory cycles were 0.645, 0.345, and 0.171 respectively and the superficial contents of the respiratory functions were 2.591, 1.008, and 0.877 respectively. The average values of the differences in the standard deviations among the whole patients at the CT room and therapy room were 0.425 for the PTP, 1.566 for the respiratory cycles, and 3.671 for the respiratory superficial contents. As for the standard deviations before and after the application of the PTP respiratory guidance system, that of the PTP was 0.265, that of the respiratory cycles was 0.474, and that of the respiratory superficial contents. The results of t-test of the values before and after free breathing and the audio-visual guidance system showed that the P-value of the PTP was 0.035, that of the cycles 0.009, and that of the respiratory superficial contents 0.010. The respiratory control could be one of the most important factors in the RGRT which determines the success or failure of a treatment. We were able to get more stable breathing with the audio-visual respiratory guidance

  8. Assessment of coronary artery bypass graft patency by multidetector computed tomography and electron-beam tomography

    NARCIS (Netherlands)

    Piers, LH; Dorgelo, J; Tio, RA; Jessurun, GAJ; Oudkerk, M; Zijlstra, F

    This case report describes the use of retrospectively ECG-gated 16-slice multidetector computed tomography (MDCT) and electron-beam tomography (EBT) for assessing bypass graft patency in two patients with recurrent angina after coronary artery bypass graft surgery. The results of each tomographic

  9. A contactless approach for respiratory gating in PET using continuous-wave radar

    Energy Technology Data Exchange (ETDEWEB)

    Ersepke, Thomas, E-mail: Thomas.Ersepke@rub.de; Büther, Florian; Heß, Mirco [European Institute for Molecular Imaging, University of Münster, Münster 48149 (Germany); Schäfers, Klaus P. [European Institute for Molecular Imaging, University of Münster, Münster 48149, Germany and DFG EXC 1003, Cluster of Excellence ‘Cells in Motion,’ Münster 48149 (Germany)

    2015-08-15

    Purpose: Respiratory gating is commonly used to reduce motion artifacts in positron emission tomography (PET). Clinically established methods for respiratory gating in PET require contact to the patient or a direct optical line between the sensor and the patient’s torso and time consuming preparation. In this work, a contactless method for capturing a respiratory signal during PET is presented based on continuous-wave radar. Methods: The proposed method relies on the principle of emitting an electromagnetic wave and detecting the phase shift of the reflected wave, modulated due to the respiratory movement of the patient’s torso. A 24 GHz carrier frequency was chosen allowing wave propagation through plastic and clothing with high reflections at the skin surface. A detector module and signal processing algorithms were developed to extract a quantitative respiratory signal. The sensor was validated using a high precision linear table. During volunteer measurements and [{sup 18}F] FDG PET scans, the radar sensor was positioned inside the scanner bore of a PET/computed tomography scanner. As reference, pressure belt (one volunteer), depth camera-based (two volunteers, two patients), and PET data-driven (six patients) signals were acquired simultaneously and the signal correlation was quantified. Results: The developed system demonstrated a high measurement accuracy for movement detection within the submillimeter range. With the proposed method, small displacements of 25 μm could be detected, not considerably influenced by clothing or blankets. From the patient studies, the extracted respiratory radar signals revealed high correlation (Pearson correlation coefficient) to those derived from the external pressure belt and depth camera signals (r = 0.69–0.99) and moderate correlation to those of the internal data-driven signals (r = 0.53–0.70). In some cases, a cardiac signal could be visualized, due to the representation of the mechanical heart motion on the skin

  10. SU-D-12A-05: Iterative Reconstruction Techniques to Enable Intrinsic Respiratory Gated CT in Mice

    Energy Technology Data Exchange (ETDEWEB)

    Sun, T; Sun, N; Tan, S [Huazhong University of Science and Technology, Wuhan, Hubei (China); Liu, Y; Mistry, N [University of Maryland School of Medicine, Baltimore, MD (United States)

    2014-06-01

    Purpose: Longitudinal studies of lung function in mice need the ability to image different phases of ventilation in free-breathing mice using retrospective gating. However, retrospective gating often produces under-sampled and uneven angular samples, resulting in severe reconstruction artifacts when using traditional FDK based reconstruction algorithms. We wanted to demonstrate the utility of iterative reconstruction method to enable intrinsic respiratory gating in small-animal CT. Methods: Free-breathing mice were imaged using a Siemens Inveon PET/micro-CT system. Evenly distributed projection images were acquired at 360 angles. Retrospective respiratory gating was performed using an intrinsic marker based on the average intensity in a region covering the diaphragm. Projections were classified into 4 and 6 phases (finer temporal resolution) resulting in 138 and 67 projections respectively. Reconstruction was carried out using 3 Methods: conventional FDK, iterative penalized least-square (PWLS) with total variation (TV), and PWLS with edge-preserving penalty. The performance of the methods was compared using contrast-to-noise (CNR) in a region of interest (ROI). Line profile through a specific region was plotted to evaluate the preserving of edges. Results: In both the cases with 4 and 6 phases, inadequate and non-uniform angular sampling results in artifacts using conventional FDK. However, such artifacts are minimized using both the iterative methods. Using both 4 and 6 phases, the iterative techniques outperformed FDK in terms of CNR and maintaining sharp edges. This is further evidenced especially with increased artifacts using FDK for 6 phases. Conclusion: This work indicates fewer artifacts and better image details can be achieved with iterative reconstruction methods in non-uniform under-sampled reconstruction. Using iterative methods can enable free-breathing intrinsic respiratory gating in small-animal CT. Further studies are needed to compare the

  11. Evaluation of the new respiratory gating system

    Science.gov (United States)

    Shi, Chengyu; Tang, Xiaoli; Chan, Maria

    2018-01-01

    Objective The newly released Respiratory Gating for Scanners (RGSC; Varian Medical Systems, Palo Alto, CA, USA) system has limited existing quality assurance (QA) protocols and pertinent publications. Herein, we report our experiences of the RGSC system acceptance and QA. Methods The RGSC system integration was tested with peripheral equipment, spatial reproducibility, and dynamic localization accuracy for regular and irregular breathing patterns, respectively. A QUASAR Respiratory Motion Phantom and a mathematical fitting method were used for data acquisition and analysis. Results The results showed that the RGSC system could accurately measure regular motion periods of 3–10 s. For irregular breathing patterns, differences from the existing Real-time Position Management (RPM; Varian Medical Systems, Palo Alto, CA) system were observed. For dynamic localization measurements, the RGSC system showed 76% agreement with the programmed test data within ±5% tolerance in terms of fitting period. As s comparison, the RPM system showed 66% agreement within ±5% tolerance, and 65% for the RGSC versus RPM measurements. Conclusions New functions and positioning accuracy improve the RGSC system’s ability to achieve higher dynamic treatment precision. A 4D phantom is helpful for the QA tests. Further investigation is required for the whole RGSC system performance QA. PMID:29722356

  12. Influence of gating phase selection on the image quality of coronary arteries in multidetector row computed tomography

    International Nuclear Information System (INIS)

    Laskowska, K.; Marzec, M.; Serafin, Z.; Nawrocka, E.; Lasek, W.; WWisniewska-Szmyt, J.; Kubica, J.

    2005-01-01

    Motion artifacts caused by cardiac movement disturb the imaging of coronary arteries with multidetector-row spiral computed tomography. The aim of this study was to determine the phase of the heart rate which provides the best quality of coronary artery imaging in retrospective ECG-gated CT. Although 75% is usually the best reconstruction phase, the optimal phase should be established individually for the patient, artery, segment, and type of tomograph for the best imaging quality. Forty-five cardiac CT angiograms of 26 patients were retrospectively evaluated. The examinations were performed with a 4-detector-row tomograph. ECG-gated retrospective reconstructions were relatively delayed at 0%, 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, and 87.5% of the cardiac cycle. Selected coronary arteries of the highest diagnostic quality were estimated in the eight phases of the cardiac cycle. Only arteries of very high image quality were selected for analysis: left coronary artery trunks (44 cases, incl. 37 stented), anterior interventricular branches (36, incl. 3 stented), circumflex branches (16), right coronary rtery branches (23), and posterior interventricular branches (4). The reconstruction phase had a statistically significant impact on the quality of imaging (p < 0.0003). Depending on the case, optimal imaging was noted in various phases, except in the 12.5 % phase. The 75% phase appeared to be the best of all those examined (p < 0.05), both in the group of arteries without stents (p < 0.0006) and in those stented (p < 0.05). In some cases of repeated examinations the best phases differed within the same patient. (author)

  13. The feasibility evaluation of Respiratory Gated radiation therapy simulation according to the Respiratory Training with lung cancer

    International Nuclear Information System (INIS)

    Hong, Mi Ran; Kim, Cheol Jong; Park, Soo Yeon; Choi, Jae Won; Pyo, Hong Ryeol

    2016-01-01

    To evaluate the usefulness of the breathing exercise,we analyzed the change in the RPM signal and the diaphragm image before 4D respiratory gated radiation therapy planning of lung cancer patients. The breathing training was enforced on 11 patients getting the 4D respiratory gated radiation therapy from April, 2016 until August. At the same time, RPM signal and diaphragm image was obtained respiration training total three steps in step 1 signal acquisition of free-breathing state, 2 steps respiratory signal acquisition through the guide of the respiratory signal, 3 steps, won the regular respiration signal to the description and repeat training. And then, acquired the minimum value, maximum value, average value, and a standard deviation of the inspiration and expiration in RPM signal and diaphragm image in each steps. Were normalized by the value of the step 1, to convert the 2,3 steps to the other distribution ratio (%), by evaluating the change in the interior of the respiratory motion of the patient, it was evaluated breathing exercise usefulness of each patient. The mean value and the standard deviation of each step were obtained with the procedure 1 of the RPM signal and the diaphragm amplitude as a 100% reference. In the RPM signal, the amplitudes and standard deviations of four patients (36.4%, eleven) decreased by 18.1%, 27.6% on average in 3 steps, and 2 patients (18.2%, 11 people) had standard deviation, It decreased by an average of 36.5%. Meanwhile, the other four patients (36.4%, eleven) decreased by an average of only amplitude 13.1%. In Step 3, the amplitude of the diaphragm image decreased by 30% on average of 9 patients (81.8%, 11 people), and the average of 2 patients (18.2%, 11 people) increased by 7.3%. However, the amplitudes of RPM signals and diaphragm image in 3 steps were reduced by 52.6% and 42.1% on average from all patients, respectively, compared to the 2 steps. Relationship between RPM signal and diaphragm image amplitude difference

  14. The feasibility evaluation of Respiratory Gated radiation therapy simulation according to the Respiratory Training with lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Mi Ran; Kim, Cheol Jong; Park, Soo Yeon; Choi, Jae Won; Pyo, Hong Ryeol [Dept. of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of)

    2016-12-15

    To evaluate the usefulness of the breathing exercise,we analyzed the change in the RPM signal and the diaphragm image before 4D respiratory gated radiation therapy planning of lung cancer patients. The breathing training was enforced on 11 patients getting the 4D respiratory gated radiation therapy from April, 2016 until August. At the same time, RPM signal and diaphragm image was obtained respiration training total three steps in step 1 signal acquisition of free-breathing state, 2 steps respiratory signal acquisition through the guide of the respiratory signal, 3 steps, won the regular respiration signal to the description and repeat training. And then, acquired the minimum value, maximum value, average value, and a standard deviation of the inspiration and expiration in RPM signal and diaphragm image in each steps. Were normalized by the value of the step 1, to convert the 2,3 steps to the other distribution ratio (%), by evaluating the change in the interior of the respiratory motion of the patient, it was evaluated breathing exercise usefulness of each patient. The mean value and the standard deviation of each step were obtained with the procedure 1 of the RPM signal and the diaphragm amplitude as a 100% reference. In the RPM signal, the amplitudes and standard deviations of four patients (36.4%, eleven) decreased by 18.1%, 27.6% on average in 3 steps, and 2 patients (18.2%, 11 people) had standard deviation, It decreased by an average of 36.5%. Meanwhile, the other four patients (36.4%, eleven) decreased by an average of only amplitude 13.1%. In Step 3, the amplitude of the diaphragm image decreased by 30% on average of 9 patients (81.8%, 11 people), and the average of 2 patients (18.2%, 11 people) increased by 7.3%. However, the amplitudes of RPM signals and diaphragm image in 3 steps were reduced by 52.6% and 42.1% on average from all patients, respectively, compared to the 2 steps. Relationship between RPM signal and diaphragm image amplitude difference

  15. SU-E-T-217: Intrinsic Respiratory Gating in Small Animal CT

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y; Smith, M; Mistry, N [University of Maryland School of Medicine, Baltimore, MD (United States)

    2014-06-01

    Purpose: Preclinical animal models of lung cancer can provide a controlled test-bed for testing dose escalation or function-based-treatment-planning studies. However, to extract lung function, i.e. ventilation, one needs to be able to image the lung at different phases of ventilation (in-hale / ex-hale). Most respiratory-gated imaging using micro-CT involves using an external ventilator and surgical intervention limiting the utility in longitudinal studies. A new intrinsic respiratory retrospective gating method was developed and tested in mice. Methods: A fixed region of interest (ROI) that covers the diaphragm was selected on all projection images to estimate the mean intensity (M). The mean intensity depends on the projection angle and diaphragm position. A 3-point moving average (A) of consecutive M values: Mpre, Mcurrent and Mpost, was calculated to be subtracted from Mcurrent. A fixed threshold was used to enable amplitude based sorting into 4 different phases of respiration. Images at full-inhale and end-exhale phases of respiration were reconstructed using the open source OSCaR. Lung volumes estimated at the 2 phases of respiration were validated against literature values. Results: Intrinsic retrospective gating was accomplished without the use of any external breathing waveform. While projection images were acquired at 360 different angles. Only 138 and 104 projections were used to reconstruct images at full-inhale and end-exhale. This often results in non-uniform under-sampled angular projections leading to some minor streaking artifacts. The calculated expiratory, inspiratory and tidal lung volumes correlated well with the values known from the literature. Conclusion: Our initial result demonstrates an intrinsic gating method that is suitable for flat panel cone beam small animal CT systems. Reduction in streaking artifacts can be accomplished by oversampling the data or using iterative reconstruction methods. This initial experience will enable

  16. MO-FG-CAMPUS-JeP2-02: Audiovisual Biofeedback Guided Respiratory-Gated MRI: An Investigation of Tumor Definition and Scan Time for Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D; Pollock, S; Keall, P [University of Sydney, Sydney, NSW (Australia); Greer, P; Lapuz, C; Ludbrook, J [Calvary Mater Newcastle, Newcastle, NSW (Australia); Kim, T [Virginia Commonwealth University, Glen Allen, VA (United States)

    2016-06-15

    Purpose: Breathing consistency variations can cause respiratory-related motion blurring and artifacts and increase in MRI scan time due to inadequate respiratory-gating and discarding of breathing cycles. In a previous study the concept of audiovisual biofeedback (AV) guided respiratory-gated MRI was tested with healthy volunteers and it demonstrated image quality improvement on anatomical structures and scan time reduction. This study tests the applicability of AV-guided respiratorygated MRI for lung cancer in a prospective patient study. Methods: Image quality and scan time were investigated in thirteen lung cancer patients who underwent two 3T MRI sessions. In the first MRI session (pre-treatment), respiratory-gated MR images with free breathing (FB) and AV were acquired at inhalation and exhalation. An RF navigator placed on the liver dome was employed for the respiratory-gated MRI. This was repeated in the second MRI session (mid-treatment). Lung tumors were delineated on each dataset. FB and AV were compared in terms of (1) tumor definition assessed by lung tumor contours and (2) intra-patient scan time variation using the total image acquisition time of inhalation and exhalation datasets from the first and second MRI sessions across 13 lung cancer patients. Results: Compared to FB AV-guided respiratory-gated MRI improved image quality for contouring tumors with sharper boundaries and less blurring resulted in the improvement of tumor definition. Compared to FB the variation of intra-patient scan time with AV was reduced by 48% (p<0.001) from 54 s to 28 s. Conclusion: This study demonstrated that AV-guided respiratorygated MRI improved the quality of tumor images and fixed tumor definition for lung cancer. These results suggest that audiovisual biofeedback breathing guidance has the potential to control breathing for adequate respiratory-gating for lung cancer imaging and radiotherapy.

  17. MO-FG-CAMPUS-JeP2-02: Audiovisual Biofeedback Guided Respiratory-Gated MRI: An Investigation of Tumor Definition and Scan Time for Lung Cancer

    International Nuclear Information System (INIS)

    Lee, D; Pollock, S; Keall, P; Greer, P; Lapuz, C; Ludbrook, J; Kim, T

    2016-01-01

    Purpose: Breathing consistency variations can cause respiratory-related motion blurring and artifacts and increase in MRI scan time due to inadequate respiratory-gating and discarding of breathing cycles. In a previous study the concept of audiovisual biofeedback (AV) guided respiratory-gated MRI was tested with healthy volunteers and it demonstrated image quality improvement on anatomical structures and scan time reduction. This study tests the applicability of AV-guided respiratorygated MRI for lung cancer in a prospective patient study. Methods: Image quality and scan time were investigated in thirteen lung cancer patients who underwent two 3T MRI sessions. In the first MRI session (pre-treatment), respiratory-gated MR images with free breathing (FB) and AV were acquired at inhalation and exhalation. An RF navigator placed on the liver dome was employed for the respiratory-gated MRI. This was repeated in the second MRI session (mid-treatment). Lung tumors were delineated on each dataset. FB and AV were compared in terms of (1) tumor definition assessed by lung tumor contours and (2) intra-patient scan time variation using the total image acquisition time of inhalation and exhalation datasets from the first and second MRI sessions across 13 lung cancer patients. Results: Compared to FB AV-guided respiratory-gated MRI improved image quality for contouring tumors with sharper boundaries and less blurring resulted in the improvement of tumor definition. Compared to FB the variation of intra-patient scan time with AV was reduced by 48% (p<0.001) from 54 s to 28 s. Conclusion: This study demonstrated that AV-guided respiratorygated MRI improved the quality of tumor images and fixed tumor definition for lung cancer. These results suggest that audiovisual biofeedback breathing guidance has the potential to control breathing for adequate respiratory-gating for lung cancer imaging and radiotherapy.

  18. Automatic tumour volume delineation in respiratory-gated PET images

    International Nuclear Information System (INIS)

    Gubbi, Jayavardhana; Palaniswami, Marimuthu; Kanakatte, Aparna; Mani, Nallasamy; Kron, Tomas; Binns, David; Srinivasan, Bala

    2011-01-01

    Positron emission tomography (PET) is a state-of-the-art functional imaging technique used in the accurate detection of cancer. The main problem with the tumours present in the lungs is that they are non-stationary during each respiratory cycle. Tumours in the lungs can get displaced up to 2.5 cm during respiration. Accurate detection of the tumour enables avoiding the addition of extra margin around the tumour that is usually used during radiotherapy treatment planning. This paper presents a novel method to detect and track tumour in respiratory-gated PET images. The approach followed to achieve this task is to automatically delineate the tumour from the first frame using support vector machines. The resulting volume and position information from the first frame is used in tracking its motion in the subsequent frames with the help of level set (LS) deformable model. An excellent accuracy of 97% is obtained using wavelets and support vector machines. The volume calculated as a result of the machine learning (ML) stage is used as a constraint for deformable models and the tumour is tracked in the remaining seven phases of the respiratory cycle. As a result, the complete information about tumour movement during each respiratory cycle is available in relatively short time. The combination of the LS and ML approach accurately delineated the tumour volume from all frames, thereby providing a scope of using PET images towards planning an accurate and effective radiotherapy treatment for lung cancer.

  19. Visualization of pulmonary vein stenosis after radio frequency ablation for treatment of atrial fibrillation using multidetector computed tomography with retrospective gating; Darstellung von Pulmonalvenenstenosen nach Radiofrequenzablation zur Behandlung von Vorhofflimmern unter Verwendung der Multidetektor Computertomographie mit retrospektivem Gating

    Energy Technology Data Exchange (ETDEWEB)

    Trabold, T.; Kuettner, A.; Heuschmid, M.; Kopp, A.F.; Claussen, C.D. [Radiologische Klinik, Abt. fuer Radiologische Diagnostik, Univ. Tuebingen (Germany); Burgstahler, C.; Mewis, C.; Schroeder, S.; Kuehlkamp, V. [Medizinische Klinik III, Abt. fuer Kardiologie, Univ. Tuebingen (Germany)

    2003-01-01

    Purpose: With the number of radio frequency ablations (RFA) for treatment of chronic atrial fibrillation increasing, the diagnostic evaluation for RFA associated pulmonary vein stenosis is getting more important. This study investigates the feasibility of the visualization of pulmonary vein stenosis using non-invasive multidetector computed tomography. Materials and Methods: Twenty-eight patients were examined following RFA-treatment. A 4-slice (20 patients) and a 16-slice (8 patients) multidetector CT scanner (SOMATOM Volume Zoom and Sensation 16, Siemens, Forchheim, Germany) with retrospective gating was used to assess the pulmonary veins. Lesion severity was determined on a semi-quantitative scale (< 30%, 30 - 50%, > 50%). Results: CT was performed without any complications in all patients. Diagnostic image quality could be obtained in all examinations. The pulmonary veins showed lesions < 30% in four patients, lesions of 30 - 50% in five patients and a stenosis > 50% in one patient. Eighteen patients showed no lesions. Conclusion: Multidetector CT of the pulmonary veins seems to be able to visualize high-grade and low-grade lesions, but larger catheter-controlled studies are needed for further assessment of the diagnostic accuracy and clinical reliability of this noninvasive method. (orig.) [German] Ziel: Mit steigender Anzahl von Radiofrequenzablationen (RFA) zur Behandlung des chronischen Vorhofflimmerns wird die Diagnostik von RFA assoziierten Pulmonalvenenstenosen zunehmend wichtiger. Ziel dieser Studie war es, die Moeglichkeit der Darstellung von Pulmonalvenenstenosen mittels der nichtinvasiven Multidetektor-Computertomographie zu untersuchen. Material und Methoden: 28 Patienten wurden im Anschluss an eine RFA-Behandlung untersucht. Die Untersuchung wurde an einem 4-Zeilen- (20 Patienten) bzw. 16-Zeilen- (8 Patienten) Multidetektor-CT (SOMATOM Volume Zoom bzw. Sensation 16, Siemens, Forchheim, Germany) mit retrospektivem Gating durchgefuehrt. Der

  20. Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality : a digital phantom study

    NARCIS (Netherlands)

    Bernatowicz, K; Keall, P; Mishra, P; Knopf, A; Lomax, A; Kipritidis, J

    PURPOSE: Prospective respiratory-gated 4D CT has been shown to reduce tumor image artifacts by up to 50% compared to conventional 4D CT. However, to date no studies have quantified the impact of gated 4D CT on normal lung tissue imaging, which is important in performing dose calculations based on

  1. Communication between the right and circumflex coronary arteries discovered incidentally by multidetector computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Se Hwan; Kim, Eui Jong; Woo, Jong Shin; Kim, Soo Joong; Youn, Hyo Chul; Oh, Joo Hyeong [College of Medicine, Kyung Hee University, Seoul (Korea, Republic of)

    2016-09-15

    Intercoronary communication is a rare congenital coronary anomaly. We present a case of a 48-year-old man with an incidentally discovered communication between the right and circumflex coronary arteries, who was admitted with chest tightness and exertional dyspnea. The initial diagnosis was made using electrocardiogram-gated multidetector computed tomography.

  2. Coronary imaging quality in routine ECG-gated multidetector CT examinations of the entire thorax: preliminary experience with a 64-slice CT system in 133 patients

    International Nuclear Information System (INIS)

    Delhaye, Damien; Remy-Jardin, Martine; Salem, Randa; Teisseire, Antoine; Khalil, Chadi; Remy, Jacques; Delannoy-Deken, Valerie; Duhamel, Alain

    2007-01-01

    To evaluate image quality in the assessment of the coronary arteries during routine ECG-gated multidetector CT (MDCT) of the chest. One hundred and thirty three patients in sinus rhythm underwent an ECG-gated CT angiographic examination of the entire chest without β-blockers with a 64-slice CT system. In 127 patients (95%), it was possible to assess the coronary arteries partially or totally; coronary artery imaging failed in six patients (5%), leading to a detailed description of the coronary arteries in 127 patients. Considering ten coronary artery segments per patient, 75% of coronary segments were assessable (948/1270 segments). When the distal segments were excluded from the analysis (i.e., seven coronary segments evaluated per patient), the percentage of assessable segments was 86% (768/889 proximal and mid coronary segments) and reached 93% (474/508) when assessing proximal segments exclusively. The mean number of assessable segments was significantly higher in patients with a heart rate ≤80 bpm (n=95) than in patients with a heart rate >80 bpm (n=38) (p<0.002). Proximal and mid-coronary segments can be adequately assessed during a whole-chest ECG-gated CT angiographic examination without administration of β-blockers in patients with a heart rate below 80 bpm. (orig.)

  3. Poster — Thur Eve — 37: Respiratory gating with an Elekta flattening filter free photon beam

    International Nuclear Information System (INIS)

    Péloquin, S; Furstoss, C; Munger, P; Wierzbicki, W; Carrier, J-F

    2014-01-01

    In cases where surgery is not possible for lung cancer treatment, stereotactic body radiation therapy (SBRT) may be an option. One problem when treating this type of cancer is the motion of the lungs caused by the patient's respiration. It is possible to reduce the impact of this movement with the use of respiratory gating. By combining respiratory gating with a flattening filter free (FFF) photon beam linac, the increased treatment time caused by a reduced beam-on time of respiratory gating methods can be compensated by the inherent increased dose rate of FFF beams. This project's aim is to create hardware and software interfaces allowing free respiration gating on an Elekta Synergy-S linac specially modified to deliver 6 MV FFF photon beams. First, a printed circuit board was created for reading the signal from a Bellows Belt from Philips (a respiration monitor belt) and transmitting an On/Off signal to the accelerator. A software was also developed to visualize patient respiration. Secondly, a FFF model was created with the Pinnacle treatment planning system from Philips. Gamma (Γ) analysis (2%, 2 mm) was used to evaluate model. For fields going from 5.6 × 5.6 to 12 × 12 cm 2 , central axis depth dose model fitting shows an average gamma value of 0.2 and 100% of gamma values remain under the Γ = 1 limit. For smaller fields (0.8 × 0.8 and 1.6 × 1.6 cm 2 ), Pinnacle has more trouble trying to fit the measurements, overestimating dose in penumbra and buildup regions

  4. Four-dimensional (4D) flow of the whole heart and great vessels using real-time respiratory self-gating

    DEFF Research Database (Denmark)

    Uribe, Sergio; Beerbaum, Philipp; Sørensen, Thomas Sangild

    2009-01-01

    Four-dimensional (4D) flow imaging has been used to study flow patterns and pathophysiology, usually focused on specific thoracic vessels and cardiac chambers. Whole-heart 4D flow at high measurement accuracy covering the entire thoracic cardiovascular system would be desirable to simplify...... and improve hemodynamic assessment. This has been a challenge because compensation of respiratory motion is difficult to achieve, but it is paramount to limit artifacts and improve accuracy. In this work we propose a self-gating technique for respiratory motion-compensation integrated into a whole-heart 4D...... flow acquisition that overcomes these challenges. Flow components are measured in all three directions for each pixel over the complete cardiac cycle, and 1D volume projections are obtained at certain time intervals for respiratory gating in real time during the acquisition. The technique was tested...

  5. Quantitative assessment of left ventricular systolic wall thickening using multidetector computed tomography

    DEFF Research Database (Denmark)

    Kristensen, Thomas S; Kofoed, Klaus F; Møller, Daniel V

    2009-01-01

    BACKGROUND: Multidetector computed tomography (MDCT) of the heart provides both anatomical and functional information. The objective of this study was to evaluate the accuracy of quantitative assessment of left ventricular contractile function in relation to two-dimensional transthoracic echocard......BACKGROUND: Multidetector computed tomography (MDCT) of the heart provides both anatomical and functional information. The objective of this study was to evaluate the accuracy of quantitative assessment of left ventricular contractile function in relation to two-dimensional transthoracic...... echocardiography (TTE). MATERIALS AND METHODS: Sixty-four patients with known or suspected coronary artery disease underwent ECG-gated 64-slice MDCT and TTE. Regional left ventricular contractile function was measured by percent systolic wall thickening (SWT) in 16 myocardial segments using MDCT, and compared...

  6. Integrating respiratory-gated PET-based target volume delineation in liver SBRT planning, a pilot study

    International Nuclear Information System (INIS)

    Riou, Olivier; Thariat, Juliette; Serrano, Benjamin; Azria, David; Paulmier, Benoit; Villeneuve, Remy; Fenoglietto, Pascal; Artenie, Antonella; Ortholan, Cécile; Faraggi, Marc

    2014-01-01

    To assess the feasibility and benefit of integrating four-dimensional (4D) Positron Emission Tomography (PET) – computed tomography (CT) for liver stereotactic body radiation therapy (SBRT) planning. 8 patients with 14 metastases were accrued in the study. They all underwent a non-gated PET and a 4D PET centered on the liver. The same CT scan was used for attenuation correction, registration, and considered the planning CT for SBRT planning. Six PET phases were reconstructed for each 4D PET. By applying an individualized threshold to the 4D PET, a Biological Internal Target Volume (BITV) was generated for each lesion. A gated Planning Target Volume (PTVg) was created by adding 3 mm to account for set-up margins. This volume was compared to a manual Planning Target Volume (PTV) delineated with the help of a semi-automatic Biological Target Volume (BTV) obtained from the non-gated exam. A 5 mm radial and a 10 mm craniocaudal margins were applied to account for tumor motion and set-up margins to create the PTV. One undiagnosed liver metastasis was discovered thanks to the 4D PET. The semi-automatic BTV were significantly smaller than the BITV (p = 0.0031). However, after applying adapted margins, 4D PET allowed a statistically significant decrease in the PTVg as compared to the PTV (p = 0.0052). In comparison to non-gated PET, 4D PET may better define the respiratory movements of liver targets and improve SBRT planning for liver metastases. Furthermore, non respiratory-gated PET exams can both misdiagnose liver metastases and underestimate the real internal target volumes

  7. Carbon-ion scanning lung treatment planning with respiratory-gated phase-controlled rescanning: simulation study using 4-dimensional CT data.

    Science.gov (United States)

    Takahashi, Wataru; Mori, Shinichiro; Nakajima, Mio; Yamamoto, Naoyoshi; Inaniwa, Taku; Furukawa, Takuji; Shirai, Toshiyuki; Noda, Koji; Nakagawa, Keiichi; Kamada, Tadashi

    2014-11-11

    To moving lung tumors, we applied a respiratory-gated strategy to carbon-ion pencil beam scanning with multiple phase-controlled rescanning (PCR). In this simulation study, we quantitatively evaluated dose distributions based on 4-dimensional CT (4DCT) treatment planning. Volumetric 4DCTs were acquired for 14 patients with lung tumors. Gross tumor volume, clinical target volume (CTV) and organs at risk (OARs) were delineated. Field-specific target volumes (FTVs) were calculated, and 48Gy(RBE) in a single fraction was prescribed to the FTVs delivered from four beam angles. The dose assessment metrics were quantified by changing the number of PCR and the results for the ungated and gated scenarios were then compared. For the ungated strategy, the mean dose delivered to 95% of the volume of the CTV (CTV-D95) was in average 45.3 ± 0.9 Gy(RBE) even with a single rescanning (1 × PCR). Using 4 × PCR or more achieved adequate target coverage (CTV-D95 = 46.6 ± 0.3 Gy(RBE) for ungated 4 × PCR) and excellent dose homogeneity (homogeneity index =1.0 ± 0.2% for ungated 4 × PCR). Applying respiratory gating, percentage of lung receiving at least 20 Gy(RBE) (lung-V20) and heart maximal dose, averaged over all patients, significantly decreased by 12% (p lung tumors without gating. The use of a respiratory-gated strategy in combination with PCR reduced excessive doses to OARs.

  8. Dual-gated cardiac PET-clinical feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Teraes, Mika; Kokki, Tommi; Noponen, Tommi; Hoppela, Erika; Sipilae, Hannu T.; Knuuti, Juhani [Turku PET Centre, PO BOX 52, Turku (Finland); Durand-Schaefer, Nicolas [General Electric Medical Systems, Buc (France); Pietilae, Mikko [Turku University Hospital, Department of Internal Medicine, Turku (Finland); Kiss, Jan [Turku University Hospital, Department of Surgery, Turku (Finland)

    2010-03-15

    Both respiratory and cardiac motions reduce image quality in myocardial imaging. For accurate imaging of small structures such as vulnerable coronary plaques, simultaneous cardiac and respiratory gating is warranted. This study tests the feasibility of a recently developed robust method for cardiac-respiratory gating. List-mode data with triggers from respiratory and cardiac cycles are rearranged into dual-gated segments and reconstructed with standard algorithms of a commercial PET/CT scanner. Cardiac gates were defined as three fixed phases and one variable diastolic phase. Chest motion was measured with a respiratory gating device and post-processed to determine gates. Preservation of quantification in dual-gated images was tested with an IEC whole-body phantom. Minipig and human studies were performed to evaluate the feasibility of the method. In minipig studies, a coronary catheter with radioactive tip was guided in coronary artery for in vivo and ex vivo acquisitions. Dual gating in humans with suspected cardiac disorders was performed using 18-F-FDG as a tracer. The method was found feasible for in vivo imaging and the radioactive catheter tip was better resolved in gated images. In human studies, the dual gating was found feasible and easy for clinical routine. Maximal movement of myocardial surface in cranio-caudal direction was over 20 mm. The shape of myocardium was clearly different between the gates and papillary muscles become more visible in diastolic images. The first clinical experiences using robust cardiac-respiratory dual gating are encouraging. Further testing in larger clinical populations using tracers designed especially for plaque imaging is warranted. (orig.)

  9. Dual-gated cardiac PET-clinical feasibility study

    International Nuclear Information System (INIS)

    Teraes, Mika; Kokki, Tommi; Noponen, Tommi; Hoppela, Erika; Sipilae, Hannu T.; Knuuti, Juhani; Durand-Schaefer, Nicolas; Pietilae, Mikko; Kiss, Jan

    2010-01-01

    Both respiratory and cardiac motions reduce image quality in myocardial imaging. For accurate imaging of small structures such as vulnerable coronary plaques, simultaneous cardiac and respiratory gating is warranted. This study tests the feasibility of a recently developed robust method for cardiac-respiratory gating. List-mode data with triggers from respiratory and cardiac cycles are rearranged into dual-gated segments and reconstructed with standard algorithms of a commercial PET/CT scanner. Cardiac gates were defined as three fixed phases and one variable diastolic phase. Chest motion was measured with a respiratory gating device and post-processed to determine gates. Preservation of quantification in dual-gated images was tested with an IEC whole-body phantom. Minipig and human studies were performed to evaluate the feasibility of the method. In minipig studies, a coronary catheter with radioactive tip was guided in coronary artery for in vivo and ex vivo acquisitions. Dual gating in humans with suspected cardiac disorders was performed using 18-F-FDG as a tracer. The method was found feasible for in vivo imaging and the radioactive catheter tip was better resolved in gated images. In human studies, the dual gating was found feasible and easy for clinical routine. Maximal movement of myocardial surface in cranio-caudal direction was over 20 mm. The shape of myocardium was clearly different between the gates and papillary muscles become more visible in diastolic images. The first clinical experiences using robust cardiac-respiratory dual gating are encouraging. Further testing in larger clinical populations using tracers designed especially for plaque imaging is warranted. (orig.)

  10. SU-E-J-169: The Dosimetric and Temporal Effects of Respiratory-Gated Radiation Therapy in Lung Cancer Patients

    International Nuclear Information System (INIS)

    Rouabhi, O; Gross, B; Xia, J; Bayouth, J

    2015-01-01

    Purpose: To evaluate the dosimetric and temporal effects of high dose rate treatment mode for respiratory-gated radiation therapy in lung cancer patients. Methods: Treatment plans from five lung cancer patients (3 nongated (Group 1), 2 gated at 80EX-80IN (Group 2)) were retrospectively evaluated. The maximum tumor motions range from 6–12 mm. Using the same planning criteria, four new treatment plans, corresponding to four gating windows (20EX–20IN, 40EX–40IN, 60EX–60IN, and 80EX–80IN), were generated for each patient. Mean tumor dose (MTD), mean lung dose (MLD), and lung V20 were used to assess the dosimetric effects. A MATLAB algorithm was developed to compute treatment time by considering gantry rotation time, time to position collimator leaves, dose delivery time (scaled relative to the gating window), and communication overhead. Treatment delivery time for each plan was estimated using a 500 MU/min dose rate for the original plans and a 1500 MU/min dose rate for the gated plans. Results: Differences in MTD were less than 1Gy across plans for all five patients. MLD and lung V20 were on average reduced between −16.1% to −6.0% and −20.0% to −7.2%, respectively for non-gated plans when compared with the corresponding gated plans, and between − 5.8% to −4.2% and −7.0% to −5.4%, respectively for plans originally gated at 80EX–80IN when compared with the corresponding 20EX-20IN to 60EX– 60IN gated plans. Treatment delivery times of gated plans using high dose rate were reduced on average between −19.7% (−1.9min) to −27.2% (−2.7min) for originally non-gated plans and −15.6% (−0.9min) to −20.3% (−1.2min) for originally 80EX-80IN gated plans. Conclusion: Respiratory-gated radiation therapy in lung cancer patients can reduce lung toxicity, while maintaining tumor dose. Using a gated high-dose-rate treatment, delivery time comparable to non-gated normal-dose-rate treatment can be achieved. This research is supported by Siemens

  11. SU-E-T-66: Characterization of Radiation Dose Associated with Dark Currents During Beam Hold for Respiratory-Gated Electron Therapy

    International Nuclear Information System (INIS)

    Hessler, J; Gupta, N; Rong, Y; Weldon, M

    2014-01-01

    Purpose: The main objective of this study was to estimate the radiation dose contributed by dark currents associated with the respiratory-gated electron therapy during beam hold. The secondary aim was to determine clinical benefits of using respiratory-gated electron therapy for left-sided breast cancer patients with positive internal mammary nodes (IMN). Methods: Measurements of the dark current-induced dose in all electron modes were performed on multiple Siemens and Varian linear accelerators by manually simulating beam-hold during respiratory gating. Dose was quantified at the machine isocenter by comparing the collected charge to the known output for all energies ranging from 6 to 18 MeV for a 10cm × 10cm field at 100 SSD with appropriate solid-water buildup. Using the Eclipse treatment planning system, we compared the additional dose associated with dark current using gated electron fields to the dose uncertainties associated with matching gated photon fields and ungated electron fields. Dose uncertainties were seen as hot and cold spots along the match line of the fields. Results: The magnitude of the dose associated with dark current is highly correlated to the energy of the beam and the amount of time the beam is on hold. For lower energies (6–12 MeV), there was minimal dark current dose (0.1–1.3 cGy/min). Higher energies (15–18 MeV) showed measurable amount of doses. The dark current associated with the electron beam-hold varied between linear accelerator vendors and depended on dark current suppression and the age of the linear accelerator. Conclusion: For energies up to 12 MeV, the dose associated with the dark current for respiratorygated electron therapy was shown to be negligible, and therefore should be considered an option for treating IMN positive left-sided breast cancer patients. However, at higher energies the benefit of respiratory gating may be outweighed by dose due to the dark current

  12. Establishing tumour tracking accuracy in free-breathing respiratory gated SBRT of lung cancer

    International Nuclear Information System (INIS)

    Wen, Chuan-Dong; Wong, C; Ackerly, T; Ruben, J; Millar, J

    2014-01-01

    Free-breathing respiratory gated SBRT of surgically inoperable lung cancer has been clinically commissioned. This study was to establish the tumour tracking accuracy under clinical conditions based on an implanted fiducial marker. A Visicoil TM marker embedded in tissue-equivalent material mounted in a phantom (ET Gating Phantom TM Brainlab) driven by a patient's breathing data was treated with the ExacTrac TM system. This one-dimensional moving marker represented a tumour motion in superior-inferior (S-I) direction measured through 4DCT study of the same patient. Both Gafchromic TM films and the stereoscopic kV images were used for tracking the position of the marker. For tumour motion at magnitudes of 10, 20 and 29 mm and treated with corresponding gate widths of 50%, 33% and 20% of free breathing amplitude, the implanted marker was able to be tracked with a deviation ≤1.53 mm to its planned position.

  13. Verification of respiratory-gated radiotherapy with new real-time tumour-tracking radiotherapy system using cine EPID images and a log file.

    Science.gov (United States)

    Shiinoki, Takehiro; Hanazawa, Hideki; Yuasa, Yuki; Fujimoto, Koya; Uehara, Takuya; Shibuya, Keiko

    2017-02-21

    A combined system comprising the TrueBeam linear accelerator and a new real-time tumour-tracking radiotherapy system, SyncTraX, was installed at our institution. The objectives of this study are to develop a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine electronic portal image device (EPID) images and a log file and to verify this treatment in clinical cases. Respiratory-gated radiotherapy was performed using TrueBeam and the SyncTraX system. Cine EPID images and a log file were acquired for a phantom and three patients during the course of the treatment. Digitally reconstructed radiographs (DRRs) were created for each treatment beam using a planning CT set. The cine EPID images, log file, and DRRs were analysed using a developed software. For the phantom case, the accuracy of the proposed method was evaluated to verify the respiratory-gated radiotherapy. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker used as an internal surrogate were calculated to evaluate the gating accuracy and set-up uncertainty in the superior-inferior (SI), anterior-posterior (AP), and left-right (LR) directions. The proposed method achieved high accuracy for the phantom verification. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker were  ⩽3 mm and  ±3 mm in the SI, AP, and LR directions. We proposed a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine EPID images and a log file and showed that this treatment is performed with high accuracy in clinical cases.

  14. Quantification of liver fat with respiratory-gated quantitative chemical shift encoded MRI.

    Science.gov (United States)

    Motosugi, Utaroh; Hernando, Diego; Bannas, Peter; Holmes, James H; Wang, Kang; Shimakawa, Ann; Iwadate, Yuji; Taviani, Valentina; Rehm, Jennifer L; Reeder, Scott B

    2015-11-01

    To evaluate free-breathing chemical shift-encoded (CSE) magnetic resonance imaging (MRI) for quantification of hepatic proton density fat-fraction (PDFF). A secondary purpose was to evaluate hepatic R2* values measured using free-breathing quantitative CSE-MRI. Fifty patients (mean age, 56 years) were prospectively recruited and underwent the following four acquisitions to measure PDFF and R2*; 1) conventional breath-hold CSE-MRI (BH-CSE); 2) respiratory-gated CSE-MRI using respiratory bellows (BL-CSE); 3) respiratory-gated CSE-MRI using navigator echoes (NV-CSE); and 4) single voxel MR spectroscopy (MRS) as the reference standard for PDFF. Image quality was evaluated by two radiologists. MRI-PDFF measured from the three CSE-MRI methods were compared with MRS-PDFF using linear regression. The PDFF and R2* values were compared using two one-sided t-test to evaluate statistical equivalence. There was no significant difference in the image quality scores among the three CSE-MRI methods for either PDFF (P = 1.000) or R2* maps (P = 0.359-1.000). Correlation coefficients (95% confidence interval [CI]) for the PDFF comparisons were 0.98 (0.96-0.99) for BH-, 0.99 (0.97-0.99) for BL-, and 0.99 (0.98-0.99) for NV-CSE. The statistical equivalence test revealed that the mean difference in PDFF and R2* between any two of the three CSE-MRI methods was less than ±1 percentage point (pp) and ±5 s(-1) , respectively (P liver PDFF and R2* and are as valid as the standard breath-hold technique. © 2015 Wiley Periodicals, Inc.

  15. Reductions in the variations of respiration signals for respiratory-gated radiotherapy when using the video-coaching respiration guiding system

    Science.gov (United States)

    Lee, Hyun Jeong; Yea, Ji Woon; Oh, Se An

    2015-07-01

    Respiratory-gated radiation therapy (RGRT) has been used to minimize the dose to normal tissue in lung-cancer radiotherapy. The present research aims to improve the regularity of respiration in RGRT by using a video-coached respiration guiding system. In the study, 16 patients with lung cancer were evaluated. The respiration signals of the patients were measured by using a realtime position management (RPM) respiratory gating system (Varian, USA), and the patients were trained using the video-coaching respiration guiding system. The patients performed free breathing and guided breathing, and the respiratory cycles were acquired for ~5 min. Then, Microsoft Excel 2010 software was used to calculate the mean and the standard deviation for each phase. The standard deviation was computed in order to analyze the improvement in the respiratory regularity with respect to the period and the displacement. The standard deviation of the guided breathing decreased to 48.8% in the inhale peak and 24.2% in the exhale peak compared with the values for the free breathing of patient 6. The standard deviation of the respiratory cycle was found to be decreased when using the respiratory guiding system. The respiratory regularity was significantly improved when using the video-coaching respiration guiding system. Therefore, the system is useful for improving the accuracy and the efficiency of RGRT.

  16. Evaluation of left ventricular function and volume with multidetector-row computed tomography. Comparison with electrocardiogram-gated single photon emission computed tomography

    International Nuclear Information System (INIS)

    Suzuki, Takeya; Yamashina, Shohei; Nanjou, Shuji; Yamazaki, Junichi

    2007-01-01

    This study compared left ventricular systolic function and volume determined by multidetector-row computed tomography (MDCT) and electrocardiogram-gated single photon emission computed tomography (G-SPECT) Thirty-seven patients with coronary artery disease and non-cardiovascular disease underwent MDCT. In this study, left ventricular ejection fraction (EF), left ventricular end-diastolic volume (EDV) and left ventricular end-systolic volume (ESV) were calculated using only two-phase imaging with MDCT. Left ventricular function and volume were compared using measurements from G-SPECT. We conducted MDCT and G-SPECT virtually simultaneously. Both the EF and ESV evaluated by MDCT closely correlated with G-SPECT (r=0.763, P 65 bpm) during MDCT significantly influenced the difference in EF calculated from MDCT and G-SPECT (P<0.05). Left ventricular function can be measured with MDCT as well as G-SPECT. However, a heart rate over 65 bpm during MDCT negatively affects the EF correlation between MDCT and G-SPECT. (author)

  17. Verification of respiratory-gated radiotherapy with new real-time tumour-tracking radiotherapy system using cine EPID images and a log file

    Science.gov (United States)

    Shiinoki, Takehiro; Hanazawa, Hideki; Yuasa, Yuki; Fujimoto, Koya; Uehara, Takuya; Shibuya, Keiko

    2017-02-01

    A combined system comprising the TrueBeam linear accelerator and a new real-time tumour-tracking radiotherapy system, SyncTraX, was installed at our institution. The objectives of this study are to develop a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine electronic portal image device (EPID) images and a log file and to verify this treatment in clinical cases. Respiratory-gated radiotherapy was performed using TrueBeam and the SyncTraX system. Cine EPID images and a log file were acquired for a phantom and three patients during the course of the treatment. Digitally reconstructed radiographs (DRRs) were created for each treatment beam using a planning CT set. The cine EPID images, log file, and DRRs were analysed using a developed software. For the phantom case, the accuracy of the proposed method was evaluated to verify the respiratory-gated radiotherapy. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker used as an internal surrogate were calculated to evaluate the gating accuracy and set-up uncertainty in the superior-inferior (SI), anterior-posterior (AP), and left-right (LR) directions. The proposed method achieved high accuracy for the phantom verification. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker were  ⩽3 mm and  ±3 mm in the SI, AP, and LR directions. We proposed a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine EPID images and a log file and showed that this treatment is performed with high accuracy in clinical cases. This work was partly presented at the 58th Annual meeting of American Association of Physicists in Medicine.

  18. Determining the most stable breathing phase for respiratory gating using velocity deformable registration in patients with lung cancer

    International Nuclear Information System (INIS)

    Aarons, Y.; Wightman, F.; Roxby, P.; Kron, T.

    2011-01-01

    Full text: Respiratory gated radiotherapy is a high-precision technique where the treatment beam is turned on during a predetermined phase of the breathing cycle in order to minimise dose to surrounding healthy dose sensitive structures. We aim to compare inspiration and expiration phases to determine which is more stable in the breathing cycle to perform respiratory gating. Methods Nine patients underwent a planning time resolved 4DCT (Philips Brilliance 16-multislice widebore) and repeat 4DCT during weeks I, 3 and 5 of a radical course of radiotherapy for lung cancer. Inspiration scans were co-registered to the same phase image of the original planning CT using rigid and then deformable registration with Velocity software. The process was repeated for scans at exhalation phase. The deformation matrix for the diaphragm was used to compare the reproducibility of breathing phases. In the majority of patients (seven of nine) the expiration phase was found to be the more stable compared with inspiration. The maximum diaphragm displacement exceeded 3 cm in one case for the registered inhalation images while the deformation was typically half of that in the exhalation images. Interestingly, several patients showed significant differences in deformation for the left and right diaphragm. Conclusions In a group of lung cancer patients we found the expiration phase to be more reproducible for delivering respiratory gated RT, when compared with inspiration.

  19. MR respiratory navigator echo gated coronary angiography at 3 T

    International Nuclear Information System (INIS)

    Chang Shixin; Wang Yibin; Zong Genlin; Hao Nanxin; Du Yushan

    2007-01-01

    Objective: To investigate the techniques and influence factors for the respiratory navigator echo triggered whole-heart coronary MR angiography (WH-CMRA) and evaluate its application in visualizing coronary arteries and the image quality. Methods: Ninety two volunteers were acquired with WH-CMRA at 3 T MR scanner using respiratory navigator-echo gated TFE sequence. Imaging quality was visually graded as 0-IV grade according to the visual inspection, average length, diameter and sharpness of coronary arteries. The correlation between the imaging quality and respiratory pattern, heart rate and navigator efficiency was analyzed. Results: The imaging quality in 92 cases was that 28 were graded as IV, 53 were graded as III, 9 were graded as II and 2 were graded as I. The successful rate of scan was 88% (81/92). The imaging quality is mainly graded as IV when the heart rate was less than 75 beats per minute (bpm) and the sharpness of vessel was (48±11)%. When heart rate was more than 75 bpm, the image quality was mostly graded as 111 and the sharpness was (33±15)%. The correlation between heart rate and imaging quality score was negative (r= -0.726, P O.05). Conclusion: 3 T WH-CMRA technique could facilitated the visualization of whole coronary arteries at free breathing but having indications on heart rate. (authors)

  20. Evaluation of prosthetic valve obstruction on electrocardiographically gated multidetector-row computed tomography--identification of subprosthetic pannus in the aortic position.

    Science.gov (United States)

    Ueda, Tomohiro; Teshima, Hideki; Fukunaga, Shuji; Aoyagi, Shigeaki; Tanaka, Hiroyuki

    2013-01-01

    This study was performed to evaluate the diagnostic role of electrocardiographically gated multidetector-row computed tomography (MDCT) for prosthetic valve obstruction (PVO) in the aortic position. Between 2002 and 2006, 9 patients were diagnosed with PVO of an aortic bileaflet mechanical valve based on echocardiographic and cineradiographic criteria. These 9 patients were examined using MDCT before replacement of the mechanical valve, and intraoperative findings were compared to morphologic periprosthetic abnormalities observed on MDCT. CT attenuation (Hounsfield units; HU) of the periprosthetic abnormalities was measured to investigate the underlying cause of the PVO. MDCT showed subprosthetic masses extending beyond the prosthetic ring into the orifice of the valve. At reoperation, presence of subprosthetic pannus was confirmed in all of the 9 patients, but no periprosthetic thrombus was found. The mean CT attenuation of the subprosthetic pannus was 170 HU, and it was significantly greater than that obtained from the interventricular septum (108 HU; Ppannus causing PVO and the mean CT attenuation of subprosthetic pannus is significantly higher than that of the interventricular septum on MDCT.

  1. SU-E-J-211: Design and Study of In-House Software Based Respiratory Motion Monitoring, Controlling and Breath-Hold Device for Gated Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, Senthilkumar [Madurai Medical College ' Govt. Rajaji Hospital, Madurai (India)

    2014-06-01

    Purpose: The purpose of this present work was to fabricate an in-house software based respiratory monitoring, controlling and breath-hold device using computer software programme which guides the patient to have uniform breath hold in response to request during the gated radiotherapy. Methods: The respiratory controlling device consists of a computer, inhouse software, video goggles, a highly sensitive sensor for measurement of distance, mounting systems, a camera, a respiratory signal device, a speaker and a visual indicator. The computer is used to display the respiratory movements of the patient with digital as well as analogue respiration indicators during the respiration cycle, to control, breath-hold and analyze the respiratory movement using indigenously developed software. Results: Studies were conducted with anthropomophic phantoms by simulating the respiratory motion on phantoms and recording the respective movements using the respiratory monitoring device. The results show good agreement between the simulated and measured movements. Further studies were conducted for 60 cancer patients with several types of cancers in the thoracic region. The respiratory movement cycles for each fraction of radiotherapy treatment were recorded and compared. Alarm indications are provided in the system to indicate when the patient breathing movement exceeds the threshold level. This will help the patient to maintain uniform breath hold during the radiotherapy treatment. Our preliminary clinical test results indicate that our device is highly reliable and able to maintain the uniform respiratory motion and breathe hold during the entire course of gated radiotherapy treatment. Conclusion: An indigenous respiratory monitoring device to guide the patient to have uniform breath hold device was fabricated. The alarm feature and the visual waveform indicator in the system guide the patient to have normal respiration. The signal from the device can be connected to the radiation

  2. SU-E-J-211: Design and Study of In-House Software Based Respiratory Motion Monitoring, Controlling and Breath-Hold Device for Gated Radiotherapy

    International Nuclear Information System (INIS)

    Shanmugam, Senthilkumar

    2014-01-01

    Purpose: The purpose of this present work was to fabricate an in-house software based respiratory monitoring, controlling and breath-hold device using computer software programme which guides the patient to have uniform breath hold in response to request during the gated radiotherapy. Methods: The respiratory controlling device consists of a computer, inhouse software, video goggles, a highly sensitive sensor for measurement of distance, mounting systems, a camera, a respiratory signal device, a speaker and a visual indicator. The computer is used to display the respiratory movements of the patient with digital as well as analogue respiration indicators during the respiration cycle, to control, breath-hold and analyze the respiratory movement using indigenously developed software. Results: Studies were conducted with anthropomophic phantoms by simulating the respiratory motion on phantoms and recording the respective movements using the respiratory monitoring device. The results show good agreement between the simulated and measured movements. Further studies were conducted for 60 cancer patients with several types of cancers in the thoracic region. The respiratory movement cycles for each fraction of radiotherapy treatment were recorded and compared. Alarm indications are provided in the system to indicate when the patient breathing movement exceeds the threshold level. This will help the patient to maintain uniform breath hold during the radiotherapy treatment. Our preliminary clinical test results indicate that our device is highly reliable and able to maintain the uniform respiratory motion and breathe hold during the entire course of gated radiotherapy treatment. Conclusion: An indigenous respiratory monitoring device to guide the patient to have uniform breath hold device was fabricated. The alarm feature and the visual waveform indicator in the system guide the patient to have normal respiration. The signal from the device can be connected to the radiation

  3. Complications of myocardial infarction on multidetector-row computed tomography of chest

    International Nuclear Information System (INIS)

    Raj, V.; Karunasaagarar, K.; Rudd, J.H.F.; Screaton, N.; Gopalan, D.

    2010-01-01

    Myocardial infarction (MI) secondary to coronary artery disease remains the leading cause of death in the western world. The advent of early reperfusion therapy has substantially decreased in-hospital mortality and has improved the outcome in survivors of the acute phase of MI. Complications of MI include ischaemic, mechanical, arrhythmic, embolic and inflammatory disturbances. Although some of these complications may be infrequent, their importance is underscored because of the potential ability to correct them with early diagnosis and appropriate treatment. The majority of these complications will be detected on clinical examination and confirmed by echocardiography. Some patients may undergo non-electrocardiogram (ECG)-gated thoracic multidetector-row computed tomography (MDCT) due to non-specific presentation. In this group, it is imperative for the radiologist to be aware of and be confident in diagnosing the complications secondary to MI. This review illustrates the spectrum and imaging features of acute and chronic complications of MI that can be visualized on both ECG-gated cardiac and non-ECG-gated thoracic MDCT.

  4. Complications of myocardial infarction on multidetector-row computed tomography of chest

    Energy Technology Data Exchange (ETDEWEB)

    Raj, V.; Karunasaagarar, K. [Department of Radiology, Papworth and Addenbrookes Hospital, Cambridge (United Kingdom); Rudd, J.H.F. [Division of Cardiovascular Medicine, University of Cambridge, Cambridge (United Kingdom); Screaton, N. [Department of Radiology, Papworth and Addenbrookes Hospital, Cambridge (United Kingdom); Gopalan, D., E-mail: deepa.gopalan@btopenworld.co [Department of Radiology, Papworth and Addenbrookes Hospital, Cambridge (United Kingdom)

    2010-11-15

    Myocardial infarction (MI) secondary to coronary artery disease remains the leading cause of death in the western world. The advent of early reperfusion therapy has substantially decreased in-hospital mortality and has improved the outcome in survivors of the acute phase of MI. Complications of MI include ischaemic, mechanical, arrhythmic, embolic and inflammatory disturbances. Although some of these complications may be infrequent, their importance is underscored because of the potential ability to correct them with early diagnosis and appropriate treatment. The majority of these complications will be detected on clinical examination and confirmed by echocardiography. Some patients may undergo non-electrocardiogram (ECG)-gated thoracic multidetector-row computed tomography (MDCT) due to non-specific presentation. In this group, it is imperative for the radiologist to be aware of and be confident in diagnosing the complications secondary to MI. This review illustrates the spectrum and imaging features of acute and chronic complications of MI that can be visualized on both ECG-gated cardiac and non-ECG-gated thoracic MDCT.

  5. Magnetic resonance imaging of the coronary arteries : clinical results from three dimensional evaluation of a respiratory gated technique

    NARCIS (Netherlands)

    van Geuns, R J; de Bruin, H G; Rensing, B J; Wielopolski, P A; Hulshoff, M D; van Ooijen, P M; Oudkerk, M; de Feyter, P J

    1999-01-01

    BACKGROUND: Magnetic resonance coronary angiography is challenging because of the motion of the vessels during cardiac contraction and respiration. Additional challenges are the small calibre of the arteries and their complex three dimensional course. Respiratory gating, turboflash acquisition, and

  6. Technical Report: TG-142 compliant and comprehensive quality assurance tests for respiratory gating

    Energy Technology Data Exchange (ETDEWEB)

    Woods, Kyle [Department of Radiation Oncology, Ohio State University, Columbus, Ohio 43210 (United States); Rong, Yi, E-mail: yrong@ucdavis.edu [Department of Radiation Oncology, University of California Davis Comprehensive Cancer Center, Sacramento, California 95817 (United States)

    2015-11-15

    Purpose: To develop and establish a comprehensive gating commissioning and quality assurance procedure in compliance with TG-142. Methods: Eight Varian TrueBeam Linacs were used for this study. Gating commissioning included an end-to-end test and baseline establishment. The end-to-end test was performed using a CIRS dynamic thoracic phantom with a moving cylinder inside the lung, which was used for carrying both optically simulated luminescence detectors (OSLDs) and Gafchromic EBT2 films while the target is moving, for a point dose check and 2D profile check. In addition, baselines were established for beam-on temporal delay and calibration of the surrogate, for both megavoltage (MV) and kilovoltage (kV) beams. A motion simulation device (MotionSim) was used to provide periodic motion on a platform, in synchronizing with a surrogate motion. The overall accuracy and uncertainties were analyzed and compared. Results: The OSLD readings were within 5% compared to the planned dose (within measurement uncertainty) for both phase and amplitude gated deliveries. Film results showed less than 3% agreement to the predicted dose with a standard sinusoid motion. The gate-on temporal accuracy was averaged at 139 ± 10 ms for MV beams and 92 ± 11 ms for kV beams. The temporal delay of the surrogate motion depends on the motion speed and was averaged at 54.6 ± 3.1 ms for slow, 24.9 ± 2.9 ms for intermediate, and 23.0 ± 20.1 ms for fast speed. Conclusions: A comprehensive gating commissioning procedure was introduced for verifying the output accuracy and establishing the temporal accuracy baselines with respiratory gating. The baselines are needed for routine quality assurance tests, as suggested by TG-142.

  7. Technical Report: TG-142 compliant and comprehensive quality assurance tests for respiratory gating

    International Nuclear Information System (INIS)

    Woods, Kyle; Rong, Yi

    2015-01-01

    Purpose: To develop and establish a comprehensive gating commissioning and quality assurance procedure in compliance with TG-142. Methods: Eight Varian TrueBeam Linacs were used for this study. Gating commissioning included an end-to-end test and baseline establishment. The end-to-end test was performed using a CIRS dynamic thoracic phantom with a moving cylinder inside the lung, which was used for carrying both optically simulated luminescence detectors (OSLDs) and Gafchromic EBT2 films while the target is moving, for a point dose check and 2D profile check. In addition, baselines were established for beam-on temporal delay and calibration of the surrogate, for both megavoltage (MV) and kilovoltage (kV) beams. A motion simulation device (MotionSim) was used to provide periodic motion on a platform, in synchronizing with a surrogate motion. The overall accuracy and uncertainties were analyzed and compared. Results: The OSLD readings were within 5% compared to the planned dose (within measurement uncertainty) for both phase and amplitude gated deliveries. Film results showed less than 3% agreement to the predicted dose with a standard sinusoid motion. The gate-on temporal accuracy was averaged at 139 ± 10 ms for MV beams and 92 ± 11 ms for kV beams. The temporal delay of the surrogate motion depends on the motion speed and was averaged at 54.6 ± 3.1 ms for slow, 24.9 ± 2.9 ms for intermediate, and 23.0 ± 20.1 ms for fast speed. Conclusions: A comprehensive gating commissioning procedure was introduced for verifying the output accuracy and establishing the temporal accuracy baselines with respiratory gating. The baselines are needed for routine quality assurance tests, as suggested by TG-142

  8. Evaluation of a direct motion estimation/correction method in respiratory-gated PET/MRI with motion-adjusted attenuation.

    Science.gov (United States)

    Bousse, Alexandre; Manber, Richard; Holman, Beverley F; Atkinson, David; Arridge, Simon; Ourselin, Sébastien; Hutton, Brian F; Thielemans, Kris

    2017-06-01

    Respiratory motion compensation in PET/CT and PET/MRI is essential as motion is a source of image degradation (motion blur, attenuation artifacts). In previous work, we developed a direct method for joint image reconstruction/motion estimation (JRM) for attenuation-corrected (AC) respiratory-gated PET, which uses a single attenuation-map (μ-map). This approach was successfully implemented for respiratory-gated PET/CT, but since it relied on an accurate μ-map for motion estimation, the question of its applicability in PET/MRI is open. The purpose of this work is to investigate the feasibility of JRM in PET/MRI and to assess the robustness of the motion estimation when a degraded μ-map is used. We performed a series of JRM reconstructions from simulated PET data using a range of simulated Dixon MRI sequence derived μ-maps with wrong attenuation values in the lungs, from -100% (no attenuation) to +100% (double attenuation), as well as truncated arms. We compared the estimated motions with the one obtained from JRM in ideal conditions (no noise, true μ-map as an input). We also applied JRM on 4 patient datasets of the chest, 3 of them containing hot lesions. Patient list-mode data were gated using a principal component analysis method. We compared SUV max values of the JRM reconstructed activity images and non motion-corrected images. We also assessed the estimated motion fields by comparing the deformed JRM-reconstructed activity with individually non-AC reconstructed gates. Experiments on simulated data showed that JRM-motion estimation is robust to μ-map degradation in the sense that it produces motion fields similar to the ones obtained when using the true μ-map, regardless of the attenuation errors in the lungs (PET/MRI clinical datasets. It provides a potential alternative to existing methods where the motion fields are pre-estimated from separate MRI measurements. © 2017 University College London (UCL). Medical Physics published by Wiley Periodicals, Inc

  9. SU-G-JeP3-09: Tumor Location Prediction Using Natural Respiratory Volume for Respiratory Gated Radiation Therapy (RGRT): System Verification Study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M; Jung, J; Yoon, D; Shin, H; Kim, S; Suh, T [The catholic university of Korea, Seoul (Korea, Republic of)

    2016-06-15

    Purpose: Respiratory gated radiation therapy (RGRT) gives accurate results when a patient’s breathing is stable and regular. Thus, the patient should be fully aware during respiratory pattern training before undergoing the RGRT treatment. In order to bypass the process of respiratory pattern training, we propose a target location prediction system for RGRT that uses only natural respiratory volume, and confirm its application. Methods: In order to verify the proposed target location prediction system, an in-house phantom set was used. This set involves a chest phantom including target, external markers, and motion generator. Natural respiratory volume signals were generated using the random function in MATLAB code. In the chest phantom, the target takes a linear motion based on the respiratory signal. After a four-dimensional computed tomography (4DCT) scan of the in-house phantom, the motion trajectory was derived as a linear equation. The accuracy of the linear equation was compared with that of the motion algorithm used by the operating motion generator. In addition, we attempted target location prediction using random respiratory volume values. Results: The correspondence rate of the linear equation derived from the 4DCT images with the motion algorithm of the motion generator was 99.41%. In addition, the average error rate of target location prediction was 1.23% for 26 cases. Conclusion: We confirmed the applicability of our proposed target location prediction system for RGRT using natural respiratory volume. If additional clinical studies can be conducted, a more accurate prediction system can be realized without requiring respiratory pattern training.

  10. Deep-inspiration breath-hold PET/CT versus free breathing PET/CT and respiratory gating PET for reference. Evaluation in 95 patients with lung cancer

    International Nuclear Information System (INIS)

    Kawano, Tsuyoshi; Ohtake, Eiji; Inoue, Tomio

    2011-01-01

    The objective of this study was to define the factors that correlate with differences in maximum standardized uptake value (SUV max ) in deep-inspiration breath-hold (DIBH) and free breathing (FB) positron emission tomography (PET)/CT admixed with respiratory gating (RG) PET for reference. Patients (n=95) with pulmonary lesions were evaluated at one facility over 33 months. After undergoing whole-body PET/CT, a RG PET and FB PET/CT scans were obtained, followed by a DIBH PET/CT scan. All scans were recorded using a list-mode dynamic collection method with respiratory gating. The RG PET was reconstructed using phase gating without attenuation correction; the FB PET was reconstructed from the RG PET sinogram datasets with attenuation correction. Respiratory motion distance, breathing cycle speed, and waveform of RG PET were recorded. The SUV max of FB PET/CT and DIBH PET/CT were recorded: the percent difference in SUV max between the FB and DIBH scans was defined as the %BH-index. The %BH-index was significantly higher for lesions in the lower lung area than in the upper lung area. Respiratory motion distance was significantly higher in the lower lung area than in the upper lung area. A significant relationship was observed between the %BH-index and respiratory motion distance. Waveforms without steady end-expiration tended to show a high %BH-index. Significant inverse relationships were observed between %BH-index and cycle speed, and between respiratory motion distance and cycle speed. Decrease in SUV max of FB PET/CT was due to tumor size, distribution of lower lung, long respiratory movement at slow breathing cycle speeds, and respiratory waveforms without steady end-expiration. (author)

  11. Low-dose respiratory-gated PET/CT: based on 30 mA tube current

    International Nuclear Information System (INIS)

    Wu Ping; Li Sijin; Zhang Yanlan; Hao Xinzhong; Qin Zhixing; Yan Min; Cheng Pengliang; Wu Zhifang

    2013-01-01

    Objective: To establish a low-dose but image-comparable respiratory-gated PET/CT (RG PET/CT) protocol based on 30 mA tube current plus other improved scanning parameters, such as the tube current, the number of respiratory phase and length of breathing cycle. Methods: Twenty-six patients with 18 F-FDG-intaking lung nodules underwent one-bed standard-dose PET/CT (120 mA, 2 min/bed) and low dose RG PET/CT (30 mA, 6 respiratory phases, 1 min/phase). The radiation dose and image quality were analyzed subsequently with signal to noise ratio (SNR) for PET and the homogeneity, noise level for CT in the water phantom respectively. Otherwise the CT images were both visual evaluated by two experienced doctors. In addition, different respiratory cycle was simulated to observe its relation with radiation dose. Results: The effective dose of low-dose RG PET/CT was 4.88∼7.69 mSv [mean (5.68±0.83) mSv]. The PET SNR showed no significance between groups. The homogeneity of 30 mA is good (< 5 HU), although noise level was high, the visual character like lobulation, speculation of lung nodule was superior in some respiratory phases. The radiation dose was positively correlated with respiratory cycle. Conclusions: The performance of low-dose RG PET/CT was comparable to those of standard-dose PET/CT based on a protocol with 30 mA tube current, 6 respiratory phases and breathing state of eupnoea. It produced a much lower radiation exposure and the image quality was enough for clinical use such as delineation of tumor active target, characterization and staging of lung nodules, etc. (authors)

  12. Accurate estimation of global and regional cardiac function by retrospectively gated multidetector row computed tomography. Comparison with cine magnetic resonance imaging

    International Nuclear Information System (INIS)

    Belge, Benedicte; Pasquet, Agnes; Vanoverschelde, Jean-Louis J.; Coche, Emmanuel; Gerber, Bernhard L.

    2006-01-01

    Retrospective reconstruction of ECG-gated images at different parts of the cardiac cycle allows the assessment of cardiac function by multi-detector row CT (MDCT) at the time of non-invasive coronary imaging. We compared the accuracy of such measurements by MDCT to cine magnetic resonance (MR). Forty patients underwent the assessment of global and regional cardiac function by 16-slice MDCT and cine MR. Left ventricular (LV) end-diastolic and end-systolic volumes estimated by MDCT (134±51 and 67±56 ml) were similar to those by MR (137±57 and 70±60 ml, respectively; both P=NS) and strongly correlated (r=0.92 and r=0.95, respectively; both P<0.001). Consequently, LV ejection fractions by MDCT and MR were also similar (55±21 vs. 56±21%; P=NS) and highly correlated (r=0.95; P<0.001). Regional end-diastolic and end-systolic wall thicknesses by MDCT were highly correlated (r=0.84 and r=0.92, respectively; both P<0.001), but significantly lower than by MR (8.3±1.8 vs. 8.8±1.9 mm and 12.7±3.4 vs. 13.3±3.5 mm, respectively; both P<0.001). Values of regional wall thickening by MDCT and MR were similar (54±30 vs. 51±31%; P=NS) and also correlated well (r=0.91; P<0.001). Retrospectively gated MDCT can accurately estimate LV volumes, EF and regional LV wall thickening compared to cine MR. (orig.)

  13. SU-E-T-247: Determinations of the Optimal Phase for Respiratory Gated Radiotherapy From Statistical Analysis Using a Visible Guidance System

    Energy Technology Data Exchange (ETDEWEB)

    Oh, S; Yea, J; Kang, M; Lee, H; Kim, S [Yeungnam University Medical Center, Daegu, Daegu (Korea, Republic of)

    2015-06-15

    Purpose: Respiratory gated radiation therapy (RGRT) is used to minimize the radiation dose to normal tissue in lung cancer patients. Determination of the optimal point in the respiratory phase of a patient is important in RGRT but it is not easy. The goal of the present study was to see if a visible guidance system is helpful in determining the optimal phase in respiratory gated therapy. Methods: The breathing signals of 23 lung cancer patients were recorded with a Real-time Position Management (RPM) respiratory gating system (Varian, USA). The patients underwent breathing training with our visible guidance system, after which their breathing signals were recorded during 5 min of free breathing and 5 min of guided breathing. The breathing signals recorded between 3 and 5 min before and after training were compared. We performed statistical analysis of the breathing signals to find the optimal duty cycle in guided breathing for RGRT. Results: The breathing signals aided by the visible guidance system had more regular cycles over time and smaller variations in the positions of the marker block than the free breathing signals. Of the 23 lung cancer patients, 19 showed statistically significant differences by time when the values obtained before and after breathing were compared (p < 0.05); 30% and 40% of the duty cycle, respectively, was determined to be the most effective, and the corresponding phases were 30 60% (duty cycle, 30%; p < 0.05) and 30 70% (duty cycle, 40%; p < 0.05). Conclusion: Respiratory regularity was significantly improved with the use of the RPM with our visible guiding system; therefore, it would help improve the accuracy and efficiency of RGRT.

  14. Congenital anomalies of coronary arteries: Diagnosis with 64 slice multidetector CT

    Energy Technology Data Exchange (ETDEWEB)

    Tariq, Rukhsana, E-mail: drrukhsanatariq@hotmail.com [Consultant Radiologists, Advanced Radiology Clinic, Behind Hamdard University Hospital, Off M.A. Jinnah Road, Karachi (Pakistan); Kureshi, Shahzad Babar [Consultant Radiologists, Advanced Radiology Clinic, Behind Hamdard University Hospital, Off M.A. Jinnah Road, Karachi (Pakistan); Siddiqui, Usman T. [Medical College, Aga Khan University, Karachi (Pakistan); Ahmed, Rashid [Consultant Radiologists, Advanced Radiology Clinic, Behind Hamdard University Hospital, Off M.A. Jinnah Road, Karachi (Pakistan)

    2012-08-15

    Objective: Congenital coronary artery anomalies are generally incidental, uncommon and asymptomatic. Some can cause severe potentially life threatening symptoms. The common mode of studying the coronary arteries is Conventional Coronary Angiogram. ECG-gated-multidetector CT is a non invasive modality. The objective of our study was to identify rare congenital coronary artery anomalies and discuss their clinical significance. Material and methods: A total number of 900 MDCT coronary angiograms were carried out at our institution between the period of April 2006 and October 2010. Patients with coronary artery anomaly constituted the subject of study. Results: The incidence of anomalous anatomical origin and course of the coronary arteries in our study was 1.55%. Hemodynamical significance was seen in five patients. 3 cases of single coronary artery originating from right coronary sinus were seen. 1 case of anomalous left coronary artery arising from main pulmonary artery was seen. 4 cases of anomalous RCA arising from left aortic cusp, 6 cases of absent LMCA with separate origin of LAD and LCX were seen. Conclusion: Multidetector row CT is a noninvasive modality in cardiac imaging. It provides superior resolution of coronary tree and its variant. No projectional vascular overlap is seen. Various postprocessing techniques outclass catheter angiography imaging. Definition of ostia and proximal course of the coronary arteries by Multidetector CT is better than catheter angiography.

  15. Congenital anomalies of coronary arteries: Diagnosis with 64 slice multidetector CT

    International Nuclear Information System (INIS)

    Tariq, Rukhsana; Kureshi, Shahzad Babar; Siddiqui, Usman T.; Ahmed, Rashid

    2012-01-01

    Objective: Congenital coronary artery anomalies are generally incidental, uncommon and asymptomatic. Some can cause severe potentially life threatening symptoms. The common mode of studying the coronary arteries is Conventional Coronary Angiogram. ECG-gated-multidetector CT is a non invasive modality. The objective of our study was to identify rare congenital coronary artery anomalies and discuss their clinical significance. Material and methods: A total number of 900 MDCT coronary angiograms were carried out at our institution between the period of April 2006 and October 2010. Patients with coronary artery anomaly constituted the subject of study. Results: The incidence of anomalous anatomical origin and course of the coronary arteries in our study was 1.55%. Hemodynamical significance was seen in five patients. 3 cases of single coronary artery originating from right coronary sinus were seen. 1 case of anomalous left coronary artery arising from main pulmonary artery was seen. 4 cases of anomalous RCA arising from left aortic cusp, 6 cases of absent LMCA with separate origin of LAD and LCX were seen. Conclusion: Multidetector row CT is a noninvasive modality in cardiac imaging. It provides superior resolution of coronary tree and its variant. No projectional vascular overlap is seen. Various postprocessing techniques outclass catheter angiography imaging. Definition of ostia and proximal course of the coronary arteries by Multidetector CT is better than catheter angiography.

  16. Respiratory-gated segment reconstruction for radiation treatment planning using 256-slice CT-scanner during free breathing

    Science.gov (United States)

    Mori, Shinichiro; Endo, Masahiro; Kohno, Ryosuke; Minohara, Shinichi; Kohno, Kazutoshi; Asakura, Hiroshi; Fujiwara, Hideaki; Murase, Kenya

    2005-04-01

    The conventional respiratory-gated CT scan technique includes anatomic motion induced artifacts due to the low temporal resolution. They are a significant source of error in radiotherapy treatment planning for the thorax and upper abdomen. Temporal resolution and image quality are important factors to minimize planning target volume margin due to the respiratory motion. To achieve high temporal resolution and high signal-to-noise ratio, we developed a respiratory gated segment reconstruction algorithm and adapted it to Feldkamp-Davis-Kress algorithm (FDK) with a 256-detector row CT. The 256-detector row CT could scan approximately 100 mm in the cranio-caudal direction with 0.5 mm slice thickness in one rotation. Data acquisition for the RS-FDK relies on the assistance of the respiratory sensing system by a cine scan mode (table remains stationary). We evaluated RS-FDK in phantom study with the 256-detector row CT and compared it with full scan (FS-FDK) and HS-FDK results with regard to volume accuracy and image noise, and finally adapted the RS-FDK to an animal study. The RS-FDK gave a more accurate volume than the others and it had the same signal-to-noise ratio as the FS-FDK. In the animal study, the RS-FDK visualized the clearest edges of the liver and pulmonary vessels of all the algorithms. In conclusion, the RS-FDK algorithm has a capability of high temporal resolution and high signal-to-noise ratio. Therefore it will be useful when combined with new radiotherapy techniques including image guided radiation therapy (IGRT) and 4D radiation therapy.

  17. Organ motion study and dosimetric impact of respiratory gating radiotherapy for esophageal cancer; Etude de mobilite organique et impact dosimetrique de l'asservissement respiratoire dans la radiotherapie des cancers de l'oesophage

    Energy Technology Data Exchange (ETDEWEB)

    Lorchel, F

    2007-04-15

    Chemoradiotherapy is now the standard treatment for locally advanced or inoperable esophageal carcinoma. In this indication, conformal radiotherapy is generally used. However, prognosis remains poor for these patients. Respiratory gating radiotherapy can decrease healthy tissues irradiation and allows escalation dose in lung, liver and breast cancer. In order to improve radiotherapy technique, we propose to study the feasibility of respiratory gating for esophageal cancer. We will study the respiratory motions of esophageal cancer to optimize target volume delineation, especially the internal margin (I.M.). We will test the correlation between tumour and chest wall displacements to prove that esophageal cancer motions are induced by respiration. This is essential before using free breathing respiratory gating systems. We will work out the dosimetric impact of respiratory gating using various dosimetric analysis parameters. We will compare dosimetric plans at end expiration, end inspiration and deep inspiration with dosimetric plan in free-breathing condition. This will allow us to establish the best respiratory phase to irradiate for each gating system. This dosimetric study will be completed with linear quadratic equivalent uniform dose (E.U.D.) calculation for each volume of interest. Previously, we will do a theoretical study of histogram dose volume gradation to point up its use. (author)

  18. SU-F-J-158: Respiratory Motion Resolved, Self-Gated 4D-MRI Using Rotating Cartesian K-Space Sampling

    Energy Technology Data Exchange (ETDEWEB)

    Han, F; Zhou, Z; Yang, Y; Sheng, K; Hu, P [UCLA School of Medicine, Los Angeles, CA (United States)

    2016-06-15

    Purpose: Dynamic MRI has been used to quantify respiratory motion of abdominal organs in radiation treatment planning. Many existing 4D-MRI methods based on 2D acquisitions suffer from limited slice resolution and additional stitching artifacts when evaluated in 3D{sup 1}. To address these issues, we developed a 4D-MRI (3D dynamic) technique with true 3D k-space encoding and respiratory motion self-gating. Methods: The 3D k-space was acquired using a Rotating Cartesian K-space (ROCK) pattern, where the Cartesian grid was reordered in a quasi-spiral fashion with each spiral arm rotated using golden angle{sup 2}. Each quasi-spiral arm started with the k-space center-line, which were used as self-gating{sup 3} signal for respiratory motion estimation. The acquired k-space data was then binned into 8 respiratory phases and the golden angle ensures a near-uniform k-space sampling in each phase. Finally, dynamic 3D images were reconstructed using the ESPIRiT technique{sup 4}. 4D-MRI was performed on 6 healthy volunteers, using the following parameters (bSSFP, Fat-Sat, TE/TR=2ms/4ms, matrix size=500×350×120, resolution=1×1×1.2mm, TA=5min, 8 respiratory phases). Supplemental 2D real-time images were acquired in 9 different planes. Dynamic locations of the diaphragm dome and left kidney were measured from both 4D and 2D images. The same protocol was also performed on a MRI-compatible motion phantom where the motion was programmed with different amplitude (10–30mm) and frequency (3–10/min). Results: High resolution 4D-MRI were obtained successfully in 5 minutes. Quantitative motion measurements from 4D-MRI agree with the ones from 2D CINE (<5% error). The 4D images are free of the stitching artifacts and their near-isotropic resolution facilitates 3D visualization and segmentation of abdominal organs such as the liver, kidney and pancreas. Conclusion: Our preliminary studies demonstrated a novel ROCK 4D-MRI technique with true 3D k-space encoding and respiratory

  19. Estimation of patient-specific imaging dose for real-time tumour monitoring in lung patients during respiratory-gated radiotherapy

    Science.gov (United States)

    Shiinoki, Takehiro; Onizuka, Ryota; Kawahara, Daisuke; Suzuki, Tatsuhiko; Yuasa, Yuki; Fujimoto, Koya; Uehara, Takuya; Hanazawa, Hideki; Shibuya, Keiko

    2018-03-01

    Purpose: To quantify the patient-specific imaging dose for real-time tumour monitoring in the lung during respiratory-gated stereotactic body radiotherapy (SBRT) in clinical cases using SyncTraX. Methods and Materials: Ten patients who underwent respiratory-gated SBRT with SyncTraX were enrolled in this study. The imaging procedure for real-time tumour monitoring using SyncTraX was simulated using Monte Carlo. We evaluated the dosimetric effect of a real-time tumour monitoring in a critical organ at risk (OAR) and the planning target volume (PTV) over the course of treatment. The relationship between skin dose and gating efficiency was also investigated. Results: For all patients, the mean D50 to the PTV, ipsilateral lung, liver, heart, spinal cord and skin was 118.3 (21.5–175.9), 31.9 (9.5–75.4), 15.4 (1.1–31.6), 10.1 (1.3–18.1), 25.0 (1.6–101.8), and 3.6 (0.9–7.1) mGy, respectively. The mean D2 was 352.0 (26.5–935.8), 146.4 (27.3–226.7), 90.7 (3.6–255.0), 42.2 (4.8–82.7), 88.0 (15.4–248.5), and 273.5 (98.3–611.6) mGy, respectively. The D2 of the skin dose was found to increase as the gating efficiency decreased. Conclusions: The additional dose to the PTV was at most 1.9% of the prescribed dose over the course of treatment for real-time tumour monitoring. For OARs, we could confirm the high dose region, which may not be susceptible to radiation toxicity. However, to reduce the skin dose from SyncTraX, it is necessary to increase the gating efficiency.

  20. Radiological emergency room management with emphasis on multidetector-row

    Energy Technology Data Exchange (ETDEWEB)

    Philipp, M.O.; Kubin, K.; Hoermann, M.; Metz, V.M. E-mail: viktor.metz@univie.ac.at

    2003-10-01

    Trauma is the fifth leading cause of death after disease of the cardiovascular system, malignomas and disease of the respiratory and digestive system. The management of severely injured patients, including radiological imaging, is a matter of ongoing development. In particular, as for the imaging modalities, multidetector-row CT represents a substantial refinement in the diagnostic work-up of multitrauma patients. Sufficient therapy within the first hour after trauma increases the patient's chances for survival significantly. Thus, therapeutic procedures and diagnostic evaluation have to be concomitant events, performed by a multidisciplinary team, namely trauma surgeon, anesthesiologist and, last but not least, radiologist. The increased performance of multidetector-row CT leads to increased spatial resolution, which is a prerequisite for sophisticated two- and three-dimensional postprocessing. The increased volume coverage speed allows for comprehensive whole-body CT at still high levels of spatial resolution, resulting in significant spare of time which influences patient's survival. Using this technique conventional imaging such as plane film or angiography may be omitted.

  1. Real-time prediction and gating of respiratory motion in 3D space using extended Kalman filters and Gaussian process regression network

    Science.gov (United States)

    Bukhari, W.; Hong, S.-M.

    2016-03-01

    The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of the radiation treatment beam due to respiratory motion. In this article, we present a real-time algorithm for predicting respiratory motion in 3D space and realizing a gating function without pre-specifying a particular phase of the patient’s breathing cycle. The algorithm, named EKF-GPRN+ , first employs an extended Kalman filter (EKF) independently along each coordinate to predict the respiratory motion and then uses a Gaussian process regression network (GPRN) to correct the prediction error of the EKF in 3D space. The GPRN is a nonparametric Bayesian algorithm for modeling input-dependent correlations between the output variables in multi-output regression. Inference in GPRN is intractable and we employ variational inference with mean field approximation to compute an approximate predictive mean and predictive covariance matrix. The approximate predictive mean is used to correct the prediction error of the EKF. The trace of the approximate predictive covariance matrix is utilized to capture the uncertainty in EKF-GPRN+ prediction error and systematically identify breathing points with a higher probability of large prediction error in advance. This identification enables us to pause the treatment beam over such instances. EKF-GPRN+ implements a gating function by using simple calculations based on the trace of the predictive covariance matrix. Extensive numerical experiments are performed based on a large database of 304 respiratory motion traces to evaluate EKF-GPRN+ . The experimental results show that the EKF-GPRN+ algorithm reduces the patient-wise prediction error to 38%, 40% and 40% in root-mean-square, compared to no prediction, at lookahead lengths of 192 ms, 384 ms and 576 ms, respectively. The EKF-GPRN+ algorithm can further reduce the prediction error by employing the gating function, albeit

  2. Real-time prediction and gating of respiratory motion in 3D space using extended Kalman filters and Gaussian process regression network

    International Nuclear Information System (INIS)

    Bukhari, W; Hong, S-M

    2016-01-01

    The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of the radiation treatment beam due to respiratory motion. In this article, we present a real-time algorithm for predicting respiratory motion in 3D space and realizing a gating function without pre-specifying a particular phase of the patient’s breathing cycle. The algorithm, named EKF-GPRN +  , first employs an extended Kalman filter (EKF) independently along each coordinate to predict the respiratory motion and then uses a Gaussian process regression network (GPRN) to correct the prediction error of the EKF in 3D space. The GPRN is a nonparametric Bayesian algorithm for modeling input-dependent correlations between the output variables in multi-output regression. Inference in GPRN is intractable and we employ variational inference with mean field approximation to compute an approximate predictive mean and predictive covariance matrix. The approximate predictive mean is used to correct the prediction error of the EKF. The trace of the approximate predictive covariance matrix is utilized to capture the uncertainty in EKF-GPRN + prediction error and systematically identify breathing points with a higher probability of large prediction error in advance. This identification enables us to pause the treatment beam over such instances. EKF-GPRN + implements a gating function by using simple calculations based on the trace of the predictive covariance matrix. Extensive numerical experiments are performed based on a large database of 304 respiratory motion traces to evaluate EKF-GPRN +  . The experimental results show that the EKF-GPRN + algorithm reduces the patient-wise prediction error to 38%, 40% and 40% in root-mean-square, compared to no prediction, at lookahead lengths of 192 ms, 384 ms and 576 ms, respectively. The EKF-GPRN + algorithm can further reduce the prediction error by employing the gating function

  3. Dynamic respiratory gated 18FDG-PET of lung tumors - a feasibility study

    International Nuclear Information System (INIS)

    Skjei Knudtsen, Ingerid; Skretting, Arne; Roedal, Jan; Brustugun, Odd Terje; Helland, Aaslaug; Malinen, Eirik

    2011-01-01

    Background. 18 FDG-PET/CT imaging is well established for diagnosis and staging of lung tumors. However, more detailed information regarding the distribution of FDG within the tumor, also as a function of time after injection may be relevant. In this study we explore the feasibility of a combined dynamic and respiratory gated (DR) PET protocol. Material and methods. A DR FDG-PET protocol for a Siemens Biograph 16 PET/CT scanner was set up, allowing data acquisition from the time of FDG injection. Breath-hold (BH) respiratory gating was performed at four intervals over a total acquisition time of 50 minutes. Thus, the PET protocol provides both motion-free images and a spatiotemporal characterization of the glucose distribution in lung tumors. Software tools were developed in-house for tentative tumor segmentation and for extracting standard uptake values (SUVs) voxel by voxel, tumor volumes and SUV gradients in all directions. Results. Four pilot patients have been investigated with the DR PET protocol. The procedure was well tolerated by the patients. The BH images appeared sharper, and SUV max /SUV mean was higher, compared to free breathing (FB) images. Also, SUV gradients in the periphery of the tumor in the BH images were in general greater than or equal to the gradients in the FB PET images. Conclusion. The DR FDG-PET protocol is feasible and the BH images have a superior quality compared to the FB images. The protocol may also provide information of relevance for radiotherapy planning and follow-up. A patient trial is needed for assessing the clinical value of the imaging protocol

  4. MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open high-field MRI scanner with respiratory gating

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ming; Huang, Jie; Xu, Yujun; He, Xiangmeng; Lue, Yubo; Liu, Qiang; Li, Chengli [Department of Interventional MRI, Shandong Medical Imaging Research Institute affiliated to Shandong University, Shandong Key Laboratory of Advanced Medical Imaging Technologies and Applications, Jinan, Shandong (China); Li, Lei [Qingdao Central Hospital, Department of Interventional Radiology, Qingdao, Shandong (China); Blanco Sequeiros, Roberto [Turku University Hospital, The South Western Finland Imaging Centre, Turku (Finland)

    2017-04-15

    To prospectively evaluate the feasibility, safety and accuracy of MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open MR scanner with respiratory gating. Sixty-five patients with 65 solitary pulmonary lesions underwent MR-guided percutaneous coaxial cutting needle biopsy using a 1.0-T open MR scanner with respiratory gating. Lesions were divided into two groups according to maximum lesion diameters: ≤2.0 cm (n = 31) and >2.0 cm (n = 34). The final diagnosis was established in surgery and subsequent histology. Diagnostic accuracy, sensitivity and specificity were compared between the groups using Fisher's exact test. Accuracy, sensitivity and specificity of MRI-guided percutaneous pulmonary biopsy in diagnosing malignancy were 96.9 %, 96.4 % and 100 %, respectively. Accuracy, sensitivity and specificity were 96.8 %, 96.3 % and 100 % for lesions 2.0 cm or smaller and 97.1 %, 96.4 % and 100 %, respectively, for lesions larger than 2.0 cm. There was no significant difference between the two groups (P > 0.05). Biopsy-induced complications encountered were pneumothorax in 12.3 % (8/65) and haemoptysis in 4.6 % (3/65). There were no serious complications. MRI-guided percutaneous biopsy using a 1.0-T open MR scanner with respiratory gating is an accurate and safe diagnostic technique in evaluation of pulmonary lesions. (orig.)

  5. Management of the baseline shift using a new and simple method for respiratory-gated radiation therapy: Detectability and effectiveness of a flexible monitoring system

    International Nuclear Information System (INIS)

    Tachibana, Hidenobu; Kitamura, Nozomi; Ito, Yasushi; Kawai, Daisuke; Nakajima, Masaru; Tsuda, Akihisa; Shiizuka, Hisao

    2011-01-01

    Purpose: In respiratory-gated radiation therapy, a baseline shift decreases the accuracy of target coverage and organs at risk (OAR) sparing. The effectiveness of audio-feedback and audio-visual feedback in correcting the baseline shift in the breathing pattern of the patient has been demonstrated previously. However, the baseline shift derived from the intrafraction motion of the patient's body cannot be corrected by these methods. In the present study, the authors designed and developed a simple and flexible system. Methods: The system consisted of a web camera and a computer running our in-house software. The in-house software was adapted to template matching and also to no preimage processing. The system was capable of monitoring the baseline shift in the intrafraction motion of the patient's body. Another marker box was used to monitor the baseline shift due to the flexible setups required of a marker box for gated signals. The system accuracy was evaluated by employing a respiratory motion phantom and was found to be within AAPM Task Group 142 tolerance (positional accuracy <2 mm and temporal accuracy <100 ms) for respiratory-gated radiation therapy. Additionally, the effectiveness of this flexible and independent system in gated treatment was investigated in healthy volunteers, in terms of the results from the differences in the baseline shift detectable between the marker positions, which the authors evaluated statistically. Results: The movement of the marker on the sternum [1.599 ± 0.622 mm (1 SD)] was substantially decreased as compared with the abdomen [6.547 ± 0.962 mm (1 SD)]. Additionally, in all of the volunteers, the baseline shifts for the sternum [-0.136 ± 0.868 (2 SD)] were in better agreement with the nominal baseline shifts than was the case for the abdomen [-0.722 ± 1.56 mm (2 SD)]. The baseline shifts could be accurately measured and detected using the monitoring system, which could acquire the movement of the marker on the sternum. The

  6. Extension of a data-driven gating technique to 3D, whole body PET studies

    International Nuclear Information System (INIS)

    Schleyer, Paul J; O'Doherty, Michael J; Marsden, Paul K

    2011-01-01

    Respiratory gating can be used to separate a PET acquisition into a series of near motion-free bins. This is typically done using additional gating hardware; however, software-based methods can derive the respiratory signal from the acquired data itself. The aim of this work was to extend a data-driven respiratory gating method to acquire gated, 3D, whole body PET images of clinical patients. The existing method, previously demonstrated with 2D, single bed-position data, uses a spectral analysis to find regions in raw PET data which are subject to respiratory motion. The change in counts over time within these regions is then used to estimate the respiratory signal of the patient. In this work, the gating method was adapted to only accept lines of response from a reduced set of axial angles, and the respiratory frequency derived from the lung bed position was used to help identify the respiratory frequency in all other bed positions. As the respiratory signal does not identify the direction of motion, a registration-based technique was developed to align the direction for all bed positions. Data from 11 clinical FDG PET patients were acquired, and an optical respiratory monitor was used to provide a hardware-based signal for comparison. All data were gated using both the data-driven and hardware methods, and reconstructed. The centre of mass of manually defined regions on gated images was calculated, and the overall displacement was defined as the change in the centre of mass between the first and last gates. The mean displacement was 10.3 mm for the data-driven gated images and 9.1 mm for the hardware gated images. No significant difference was found between the two gating methods when comparing the displacement values. The adapted data-driven gating method was demonstrated to successfully produce respiratory gated, 3D, whole body, clinical PET acquisitions.

  7. Gated listmode acquisition with the QuadHIDAC animal PET to image mouse hearts

    International Nuclear Information System (INIS)

    Schaefers, K.P.; Lang, N.; Stegger, L.; Schober, O.; Schaefers, M.

    2006-01-01

    Purpose: the aim of this study was to develop ECG and respiratory gating in combination with listmode acquisition for the quadHIDAC small-animal PET scanner. Methods: ECG and respiratory gating was realized with the help of an external trigger device (BioVET) synchronized with the listmode acquisition. Listmode data of a mouse acquisition (injected with 6.5 MBq of 18 F-FDG) were sorted according to three different gating definitions: 12 cardiac gates, 8 respiratory gates and a combination of 8 cardiac and 8 respiratory gates. Images were reconstructed with filtered back-projection (ramp filter), and parameters like left ventricular wall thickness (WT), wall-to-wall separation (WS) and blood to myocardium activity ratios (BMR) were calculated. Results: cardiac gated images show improvement of all parameters (WT 2.6 mm, WS 4.1 mm, BRM 2.3) in diastole compared to ungated images (WT 3.0 mm, WS 3.4 mm, BMR 1.3). Respiratory gating had little effect on calculated parameters. Conclusion: ECG gating with the quadHIDAC can improve myocardial image quality in mice. This could have a major impact on the calculation of an image-derived input function for kinetic modelling. (orig.)

  8. In vivo measurements of relaxation process in the human liver by MRI. The role of respiratory gating/triggering

    DEFF Research Database (Denmark)

    Thomsen, C; Henriksen, O; Ring, P

    1988-01-01

    In vivo estimation of relaxation processes in the liver by magnetic resonance imaging (MRI) may be helpful for characterization of various pathological conditions in the liver. However, such measurements may be significantly hampered by movement of the liver with the respiration. The effect...... of synchronization of data acquisition to the respiratory cycle on measured T1- and T2-relaxation curves was studied in normal subjects, patients with diffuse liver disease, and patients with focal liver pathology. Multi spin echo sequences with five different repetition times were used. The measurements were...... carried out with and without respiratory gating/triggering. In the healthy subjects as well as in the patients with diffuse liver diseases respiratory synchronization did not alter the obtained relaxation curves. However, in the patients with focal pathology the relaxation curves were significantly...

  9. Study on motion artifacts in coronary arteries with an anthropomorphic moving heart phantom on an ECG-gated multidetector computed tomography unit

    International Nuclear Information System (INIS)

    Greuter, Marcel J.W.; Dorgelo, Joost; Tukker, Wim G.J.; Oudkerk, Matthijs

    2005-01-01

    Acquisition time plays a key role in the quality of cardiac multidetector computed tomography (MDCT) and is directly related to the rotation time of the scanner. The purpose of this study is to examine the influence of heart rate and a multisector reconstruction algorithm on the image quality of coronary arteries of an anthropomorphic adjustable moving heart phantom on an ECG-gated MDCT unit. The heart phantom and a coronary artery phantom were used on a MDCT unit with a rotation time of 500 ms. The movement of the heart was determined by analysis of the images taken at different phases. The results indicate that the movement of the coronary arteries on the heart phantom is comparable to that in a clinical setting. The influence of the heart rate on image quality and artifacts was determined by analysis of several heart rates between 40 and 80 bpm where the movement of the heart was synchronized using a retrospective ECG-gated acquisition protocol. The resulting reformatted volume rendering images of the moving heart and the coronary arteries were qualitatively compared as a result of the heart rate. The evaluation was performed on three independent series by two independent radiologists for the image quality of the coronary arteries and the presence of artifacts. The evaluation shows that at heart rates above 50 bpm the influence of motion artifacts in the coronary arteries becomes apparent. In addition the influence of a dedicated multisector reconstruction technique on image quality was determined. The results show that the image quality of the coronary arteries is not only related to the heart rate and that the influence of the multisector reconstruction technique becomes significant above 70 bpm. Therefore, this study proves that from the actual acquisition time per heart cycle one cannot determine an actual acquisition time, but only a mathematical acquisition time. (orig.)

  10. Prospective ECG triggering reduces prosthetic heart valve-induced artefacts compared with retrospective ECG gating on 256-slice CT

    NARCIS (Netherlands)

    Symersky, P.; Habets, J.; Westers, P.; Mol, de B.A.J.M.; Prokop, M.; Budde, R.P.J.

    2012-01-01

    Objectives Multidetector computed tomography (MDCT) has diagnostic value for the evaluation of prosthetic heart valve (PHV) dysfunction but it is hampered by artefacts. We hypothesised that image acquisition using prospective triggering instead of retrospective gating would reduce artefacts related

  11. Main technical aspects and clinical benefits of respiratory Gating for radiotherapy of lung neoplasm

    International Nuclear Information System (INIS)

    Benites, Rafaela Freitas Oliveira

    2016-01-01

    The concern with the irradiation of lung tumors is that many of them can move along the breathing, which can cause problems in defining accurately the target and increases the irradiation of normal tissues. The objectives are to present the 4D CT principles, image acquisition, reconstruction and application in planning of the radiotherapy. It justifies the quick implantation, improvements in acquisition and images, the possibility in quantify the tumor movement, verifying strategies and delivery treatment. It's concluded that the toxicity risk is reduced with the respiratory gating, and the results suggests that the closed RT will be of clinical relevance. (author)

  12. A novel respiratory motion compensation strategy combining gated beam delivery and mean target position concept - A compromise between small safety margins and long duty cycles

    International Nuclear Information System (INIS)

    Guckenberger, Matthias; Kavanagh, Anthony; Webb, Steve; Brada, Michael

    2011-01-01

    Purpose: To evaluate a novel respiratory motion compensation strategy combining gated beam delivery with the mean target position (MTP) concept for pulmonary stereotactic body radiotherapy (SBRT). Materials and methods: Four motion compensation strategies were compared for 10 targets with motion amplitudes between 6 mm and 31 mm: the internal target volume concept (plan ITV ); the MTP concept where safety margins were adapted based on 4D dose accumulation (plan MTP ); gated beam delivery without margins for motion compensation (plan gated ); a novel approach combining gating and the MTP concept (plan gated and MTP ). Results: For 5/10 targets with an average motion amplitude of 9 mm, the differences in the mean lung dose (MLD) between plan gated and plan MTP were gated and MTP . Despite significantly shorter duty cycles, plan gated reduced the MLD by gated and MTP . The MLD was increased by 18% in plan MTP compared to that of plan gated and MTP . Conclusions: For pulmonary targets with motion amplitudes >10-15 mm, the combination of gating and the MTP concept allowed small safety margins with simultaneous long duty cycles.

  13. Detection and compensation of organ/lesion motion using 4D-PET/CT respiratory gated acquisition techniques

    International Nuclear Information System (INIS)

    Bettinardi, Valentino; Picchio, Maria; Di Muzio, Nadia; Gianolli, Luigi; Gilardi, Maria Carla; Messa, Cristina

    2010-01-01

    Purpose: To describe the degradation effects produced by respiratory organ and lesion motion on PET/CT images and to define the role of respiratory gated (RG) 4D-PET/CT techniques to compensate for such effects. Methods: Based on the literature and on our own experience, technical recommendations and clinical indications for the use of RG 4D PET/CT have been outlined. Results: RG 4D-PET/CT techniques require a state of the art PET/CT scanner, a respiratory monitoring system and dedicated acquisition and processing protocols. Patient training is particularly important to obtain a regular breathing pattern. An adequate number of phases has to be selected to balance motion compensation and statistical noise. RG 4D PET/CT motion free images may be clinically useful for tumour tissue characterization, monitoring patient treatment and target definition in radiation therapy planning. Conclusions: RG 4D PET/CT is a valuable tool to improve image quality and quantitative accuracy and to assess and measure organ and lesion motion for radiotherapy planning.

  14. Left ventricular volume measurements with free breathing respiratory self-gated 3-dimensional golden angle radial whole-heart cine imaging - Feasibility and reproducibility.

    Science.gov (United States)

    Holst, Karen; Ugander, Martin; Sigfridsson, Andreas

    2017-11-01

    To develop and evaluate a free breathing respiratory self-gated isotropic resolution technique for left ventricular (LV) volume measurements. A 3D radial trajectory with double golden-angle ordering was used for free-running data acquisition during free breathing in 9 healthy volunteers. A respiratory self-gating signal was extracted from the center of k-space and used with the electrocardiogram to bin all data into 3 respiratory and 25 cardiac phases. 3D image volumes were reconstructed and the LV endocardial border was segmented. LV volume measurements and reproducibility from 3D free breathing cine were compared to conventional 2D breath-held cine. No difference was found between 3D free breathing cine and 2D breath-held cine with regards to LV ejection fraction, stroke volume, end-systolic volume and end-diastolic volume (Pcine and 2D breath-held cine (Pcine and conventional 2D breath-held cine showed similar values and test-retest repeatability for LV volumes in healthy volunteers. 3D free breathing cine enabled retrospective sorting and arbitrary angulation of isotropic data, and could correctly measure LV volumes during free breathing acquisition. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Coronary artery assessment by multidetector computed tomography in patients with prosthetic heart valves

    International Nuclear Information System (INIS)

    Habets, Jesse; Mali, Willem P.T.M.; Budde, Ricardo P.J.; Brink, Renee B.A. van den; Uijlings, Ruben; Spijkerboer, Anje M.; Chamuleau, Steven A.J.

    2012-01-01

    Patients with prosthetic heart valves may require assessment for coronary artery disease. We assessed whether valve artefacts hamper coronary artery assessment by multidetector CT. ECG-gated or -triggered CT angiograms were selected from our PACS archive based on the presence of prosthetic heart valves. The best systolic and diastolic axial reconstructions were selected for coronary assessment. Each present coronary segment was scored for the presence of valve-related artefacts prohibiting coronary artery assessment. Scoring was performed in consensus by two observers. Eighty-two CT angiograms were performed on a 64-slice (n = 27) or 256-slice (n = 55) multidetector CT. Eighty-nine valves and five annuloplasty rings were present. Forty-three out of 1160 (3.7%) present coronary artery segments were non-diagnostic due to valve artefacts (14/82 patients). Valve artefacts were located in right coronary artery (15/43; 35%), left anterior descending artery (2/43; 5%), circumflex artery (14/43; 32%) and marginal obtuse (12/43; 28%) segments. All cobalt-chrome containing valves caused artefacts prohibiting coronary assessment. Biological and titanium-containing valves did not cause artefacts except for three specific valve types. Most commonly implanted prosthetic heart valves do not hamper coronary assessment on multidetector CT. Cobalt-chrome containing prosthetic heart valves preclude complete coronary artery assessment because of severe valve artefacts. circle Most commonly implanted prosthetic heart valves do not hamper coronary artery assessment circle Prosthetic heart valve composition determines the occurrence of prosthetic heart valve-related artefacts circle Bjoerk-Shiley and Sorin tilting disc valves preclude diagnostic coronary artery segment assessment. (orig.)

  16. Multi-detector computed tomography (MDCT imaging of cardiovascular effects of pulmonary embolism: What the radiologists need to know

    Directory of Open Access Journals (Sweden)

    Mohamed Aboul-fotouh E. Mourad

    2017-09-01

    Full Text Available Background: Patients with pulmonary embolism have high mortality and morbidity rate due to right heart failure and circulatory collapse leading to sudden death. Multi-detector computed tomography MDCT can efficiently evaluate the cardiovascular factors related to pulmonary embolism. Objectives: To evaluate the diagnostic accuracy of multi-detector computed tomography (MDCT in differentiation of between sever and non-severe pulmonary embolism groups depending on the associated cardiovascular parameters and create a simple reporting system. Patients & methods: Prospective study contained 145 patients diagnosed clinically pulmonary embolism. All patients were examined by combined electrocardiographically gated computed tomography pulmonary angiography-computed tomography venography (ECG-CTPA-CTV using certain imaging criteria in a systematic manner. Results: Our study revealed 95 and 55 non-severe and severe pulmonary embolism groups respectively. Many cardiovascular parameters related to pulmonary embolism shows significant p value and can differentiate between sever and non-severe pulmonary embolism patients include pulmonary artery diameter, intraventricular septum flattening, bowing, superior vena cava and Azygos vein diameters, right and left ventricular diameters. Conclusion: Multi-detector computed tomography (MDCT can be valuable to assess the severity of pulmonary embolism using the related cardiovascular parameters and leading the management strategy aim for best outcome. Keywords: Pulmonary embolism, MDCT, Cardiovascular, Computed tomography venography

  17. The Analysis of Predictive Factors for the Identification of Patients Who Could Benefit from Respiratory-Gated Radiotherapy in Non-Small Cell Lung Cancer

    International Nuclear Information System (INIS)

    Jang, Seong Soon; Park, Ji Chan

    2009-01-01

    4DCT scans performed for radiotherapy were retrospectively analyzed to assess the possible benefits of respiratory gating in non-small cell lung cancer (NSCLC) and established the predictive factors for identifying patients who could benefit from this approach. Three treatment planning was performed for 15 patients with stage I∼III NSCLC using different planning target volumes (PTVs) as follows: 1) PTVroutine, derived from the addition of conventional uniform margins to gross tumor volume (GTV) of a single bin, 2) PTVall phases (patient-specific PTV), derived from the composite GTV of all 6 bins of the 4DCT, and 3) PTVgating, derived from the composite GTV of 3 consecutive bins at end-exhalation. The reductions in PTV were 43.2% and 9.5%, respectively, for the PTVall phases vs. PTVroutine and PTVgating vs. PTVall phases. Compared to PTVroutine, the use of PTVall phases and PTVgating reduced the mean lung dose (MLD) by 18.1% and 21.6%, and V20 by 18.2% and 22.0%, respectively. Significant correlations were seen between certain predictive factors selected from the tumor mobility and volume analysis, such as the 3D mobility vector, the reduction in 3D mobility and PTV with gating, and the ratio of GTV overlap between 2 extreme bins and additional reductions in both MLD and V20 with gating. The additional benefits with gating compared to the use of patient-specific PTV were modest; however, there were distinct correlations and differences according to the predictive factors. Therefore, these predictive factors might be useful for identifying patients who could benefit from respiratory-gated radiotherapy

  18. Management of respiratory motion in radiation oncology

    International Nuclear Information System (INIS)

    Vedam, Subrahmanya Sastry

    2003-01-01

    Respiration affects the instantaneous position of almost all thoracic and abdominal structures (lung, breast, liver, pancreas, etc.), posing significant problems in the radiotherapy of tumors located at these sites. The diaphragm, for example, has been shown to move approximately 1.5 cm in the superior-inferior direction during normal breathing. During radiotherapy, margin expansion around the tumor, based on an estimate of the expected range of tumor motion, is commonly employed to ensure adequate dose coverage. Such a margin estimate may or may not encompass the 'current' extent of motion exhibited by the tumor, resulting in either a higher dose to the surrounding normal tissue or a cold spot in the tumor volume, leading to poor prognosis. Accounting for respiratory motion by active management during radiotherapy can, however, potentiate a reduction in the amount of high dose to normal tissue. Active management of respiratory motion forms the primary theme of this dissertation. Among the various techniques available to manage respiratory motion, our research focused on respiratory gated and respiration synchronized radiotherapy, with an external marker to monitor respiratory motion. Multiple session recordings of diaphragm and external marker motion revealed a consistent linear relationship, validating the use of external marker motion as a 'surrogate' for diaphragm motion. The predictability of diaphragm motion based on such external marker motion both within and between treatment sessions was also determined to be of the order of 0.1 cm. Gating during exhalation was found to be more reproducible than gating during inhalation. Although, a reduction in the 'gate' width achieved a modest reduction in the margins added around the tumor further reduction was limited by setup error. A motion phantom study of the potential gains from respiratory gating indicated margin reduction of 0.2-1.1 cm while employing gating. In addition, gating also improved the quality of

  19. Comparative evaluation of respiratory-gated and ungated FDG-PET for target volume definition in radiotherapy treatment planning for pancreatic cancer.

    Science.gov (United States)

    Kishi, Takahiro; Matsuo, Yukinori; Nakamura, Akira; Nakamoto, Yuji; Itasaka, Satoshi; Mizowaki, Takashi; Togashi, Kaori; Hiraoka, Masahiro

    2016-08-01

    The purpose of this study was to evaluate the usefulness of respiratory-gated positron emission tomography (4D-PET) in pancreatic cancer radiotherapy treatment planning (RTTP). Fourteen patients with 18F-fluorodeoxyglucose (FDG)-avid pancreatic tumours were evaluated between December 2013 and March 2015. Two sets of volumes were contoured for the pancreatic tumour of each patient. The biological target volume in three-dimensional RTTP (BTV3D) was contoured using conventional respiratory un-gated PET. The BTV3D was then expanded using population-based margins to generate a series of internal target volume 3D (ITV3D) values. The ITV 4D (ITV4D) was contoured using 4D-PET. Each of the five phases of 4D-PET was used for 4D contouring, and the ITV4D was constructed by summing the volumes defined on the five individual 4D-PET images. The relative volumes and normalized volumetric overlap were computed between ITV3D and ITV4D. On average, the FDG-avid tumour volumes were 1.6 (range: 0.8-2.3) fold greater in the ITV4D than in the BTV3D. On average, the ITV3D values were 2.0 (range: 1.1-3.4) fold larger than the corresponding ITV4D values. The ITV generated from 4D-PET can be used to improve the accuracy or reduce normal tissue irradiation compared with conventional un-gated PET-based ITV. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Quality assurance program of a respiratory gating irradiation system based on external and internal fiducial markers; Programa de garantia de calidad de un sistema de irradiacion con control respiratorio basado en marcadores fiduciales externos e internos

    Energy Technology Data Exchange (ETDEWEB)

    Zucca Aparicio, D.; Perez Moreno, J. M.; Fernandez Leton, P.; Garcia Ruiz-Zorrilla, J.; Minambres Moro, A.

    2011-07-01

    Respiratory Gating involves the administration of radiation during treatment delivery within a particular portion of the patients breathing cycle, so the absorbed dose administration with respiratory control techniques requires specific quality control to ensure the correctness of the delivered dose. The establishment of a Quality Control Program (QC) is proposed for the Respiratory Gating based techniques in order to have a better understanding of how this system works and to know its associated dosimetric impact. The influence of the CT acquisition under respiratory motion conditions has been analyzed for the treatment isocenter localization, using internal and external fiducial markers with IGRT techniques that allow the correlation of the isocenter positioning with the phase of the respiratory cycle. Radiation delivery in the presence of intra fraction organ motion causes an averaging or blurring of the static dose distribution over the path of motion increasing the beam penumbra of the radiation field and reducing the therapeutic region when the irradiation is not breath controlled. The feasibility of intensity modulated treatments (IMRT) for both static and dynamic techniques, managed by respiratory control has been tested, demonstrating the possibility of synchronizing the movement of the leaves in the microfluorimeter collimator (mMLC) with the gated beam irradiation. (Author) 45 refs.

  1. Quality assurance device for four-dimensional IMRT or SBRT and respiratory gating using patient-specific intrafraction motion kernels.

    Science.gov (United States)

    Nelms, Benjamin E; Ehler, Eric; Bragg, Henry; Tomé, Wolfgang A

    2007-09-17

    Emerging technologies such as four-dimensional computed tomography (4D CT) and implanted beacons are expected to allow clinicians to accurately model intrafraction motion and to quantitatively estimate internal target volumes (ITVs) for radiation therapy involving moving targets. In the case of intensity-modulated (IMRT) and stereotactic body radiation therapy (SBRT) delivery, clinicians must consider the interplay between the temporal nature of the modulation and the target motion within the ITV. A need exists for a 4D IMRT/SBRT quality assurance (QA) device that can incorporate and analyze customized intrafraction motion as it relates to dose delivery and respiratory gating. We built a 4D IMRT/SBRT prototype device and entered (X, Y, Z)(T) coordinates representing a motion kernel into a software application that 1. transformed the kernel into beam-specific two-dimensional (2D) motion "projections," 2. previewed the motion in real time, and 3. drove a recision X-Y motorized device that had, atop it, a mounted planar IMRT QA measurement device. The detectors that intersected the target in the beam's-eye-view of any single phase of the breathing cycle (a small subset of all the detectors) were defined as "target detectors" to be analyzed for dose uniformity between multiple fractions. Data regarding the use of this device to quantify dose variation fraction-to-fraction resulting from target motion (for several delivery modalities and with and without gating) have been recently published. A combined software and hardware solution for patient-customized 4D IMRT/SBRT QA is an effective tool for assessing IMRT delivery under conditions of intrafraction motion. The 4D IMRT QA device accurately reproduced the projected motion kernels for all beam's-eye-view motion kernels. This device has been proved to, effectively quantify the degradation in dose uniformity resulting from a moving target within a static planning target volume, and, integrate with a commercial

  2. Quality assurance device for four‐dimensional IMRT or SBRT and respiratory gating using patient‐specific intrafraction motion kernels

    Science.gov (United States)

    Ehler, Eric; Bragg, Henry; Tomé, Wolfgang A.

    2007-01-01

    Emerging technologies such as four‐dimensional computed tomography (4D CT) and implanted beacons are expected to allow clinicians to accurately model intrafraction motion and to quantitatively estimate internal target volumes (ITVs) for radiation therapy involving moving targets. In the case of intensity‐modulated (IMRT) and stereotactic body radiation therapy (SBRT) delivery, clinicians must consider the interplay between the temporal nature of the modulation and the target motion within the ITV. A need exists for a 4D IMRT/SBRT quality assurance (QA) device that can incorporate and analyze customized intrafraction motion as it relates to dose delivery and respiratory gating. We built a 4D IMRT/SBRT prototype device and entered (X, Y, Z)(T) coordinates representing a motion kernel into a software application that transformed the kernel into beam‐specific two‐dimensional (2D) motion “projections,”previewed the motion in real time, anddrove a precision X–Y motorized device that had, atop it, a mounted planar IMRT QA measurement device. The detectors that intersected the target in the beam's‐eye‐view of any single phase of the breathing cycle (a small subset of all the detectors) were defined as “target detectors” to be analyzed for dose uniformity between multiple fractions. Data regarding the use of this device to quantify dose variation fraction‐to‐fraction resulting from target motion (for several delivery modalities and with and without gating) have been recently published. A combined software and hardware solution for patient‐customized 4D IMRT/ SBRT QA is an effective tool for assessing IMRT delivery under conditions of intrafraction motion. The 4D IMRT QA device accurately reproduced the projected motion kernels for all beam's‐eye‐view motion kernels. This device has been proved to • effectively quantify the degradation in dose uniformity resulting from a moving target within a static planning target volume, and • integrate

  3. The relation between respiratory motion artifact correction and lung standardized uptake value

    International Nuclear Information System (INIS)

    Yin Lijie; Liu Xiaojian; Liu Jie; Xu Rui; Yan Jue

    2014-01-01

    PET/CT is playing an important role in disease diagnosis and therapeutic evaluation. But the respiratory motion artifact may bring trouble in diagnosis and therapy. There are many methods to correct the respiratory motion artifact. Respiratory gated PET/CT is applied most extensively of them. Using respiratory gated PET/CT to correct respiratory motion artifact can increase the maximum standardized uptake value of lung lesion obviously, thereby improving the quality of image and accuracy of diagnosis. (authors)

  4. A Comparison of Amplitude-Based and Phase-Based Positron Emission Tomography Gating Algorithms for Segmentation of Internal Target Volumes of Tumors Subject to Respiratory Motion

    International Nuclear Information System (INIS)

    Jani, Shyam S.; Robinson, Clifford G.; Dahlbom, Magnus; White, Benjamin M.; Thomas, David H.; Gaudio, Sergio; Low, Daniel A.; Lamb, James M.

    2013-01-01

    Purpose: To quantitatively compare the accuracy of tumor volume segmentation in amplitude-based and phase-based respiratory gating algorithms in respiratory-correlated positron emission tomography (PET). Methods and Materials: List-mode fluorodeoxyglucose-PET data was acquired for 10 patients with a total of 12 fluorodeoxyglucose-avid tumors and 9 lymph nodes. Additionally, a phantom experiment was performed in which 4 plastic butyrate spheres with inner diameters ranging from 1 to 4 cm were imaged as they underwent 1-dimensional motion based on 2 measured patient breathing trajectories. PET list-mode data were gated into 8 bins using 2 amplitude-based (equal amplitude bins [A1] and equal counts per bin [A2]) and 2 temporal phase-based gating algorithms. Gated images were segmented using a commercially available gradient-based technique and a fixed 40% threshold of maximum uptake. Internal target volumes (ITVs) were generated by taking the union of all 8 contours per gated image. Segmented phantom ITVs were compared with their respective ground-truth ITVs, defined as the volume subtended by the tumor model positions covering 99% of breathing amplitude. Superior-inferior distances between sphere centroids in the end-inhale and end-exhale phases were also calculated. Results: Tumor ITVs from amplitude-based methods were significantly larger than those from temporal-based techniques (P=.002). For lymph nodes, A2 resulted in ITVs that were significantly larger than either of the temporal-based techniques (P<.0323). A1 produced the largest and most accurate ITVs for spheres with diameters of ≥2 cm (P=.002). No significant difference was shown between algorithms in the 1-cm sphere data set. For phantom spheres, amplitude-based methods recovered an average of 9.5% more motion displacement than temporal-based methods under regular breathing conditions and an average of 45.7% more in the presence of baseline drift (P<.001). Conclusions: Target volumes in images generated

  5. Evaluation of MotionSim XY/4D for patient specific QA of respiratory gated treatment for lung cancer

    International Nuclear Information System (INIS)

    Wen, C.; Ackerly, T.; Lancaster, C.; Bailey, N.

    2011-01-01

    Full text: A commercial system-MotionSim XY/4D(TM) capable of simulating two-dimensional tumour motion and measuring planar dose with diode-matrix was evaluated at the Alfred Hospital, for establishing patient-specific QA programme of respiratory gated treatment of lung cancer. This study presents the investigation of accuracies, limitations and the practical aspects of that system. Planar doses generated on iPlan-TM by mapping clinical beams to a scanned-in water phantom were measured by MotionSim XY/4D-TM with 5 cm water equivalent build-up at normal incidence. The gated delivery using ExacTrac-TM through tracking infrared markers simulating external respiration surrogate was measured simultaneously with Gaf-ChromicR RTQA2 film and MapCHECK 2TM . Dose maps of both non-gated and gated beams with 30% duty cycle were compared with both film and diodes measurements. Differences in dose distribution were analysed with built-in tools in MapCHECK2 TM and the effect of residual motion within the beamenabled window was then assessed. Preliminary results indicate that difference between Gafchromic film and MapCHECK2 measurements of same beam was ignorable. Gated dose delivery to a target at 9 mm maximum motion was in good agreement with planned dose. Complement to measurements suggested in AAPM Report No.9 I I, this QA device can detect any random error and assess the magnitude of residual target motion through analysing differences between planned and delivered doses as gamma function. Although some user-friendliness aspects could be improved, it meets its specification and can be used for routine clinical QA purposes provided calibrations were performed and procedures were followed.

  6. [Comparison of radiation dose reduction of prospective ECG-gated one beat scan using 320 area detector CT coronary angiography and prospective ECG-gated helical scan with high helical pitch (FlashScan) using 64 multidetector-row CT coronary angiography].

    Science.gov (United States)

    Matsutani, Hideyuki; Sano, Tomonari; Kondo, Takeshi; Fujimoto, Shinichiro; Sekine, Takako; Arai, Takehiro; Morita, Hitomi; Takase, Shinichi

    2010-12-20

    A high radiation dose associated with 64 multidetector-row computed tomography (64-MDCT) is a major concern for physicians and patients alike. A new 320 row area detector computed tomography (ADCT) can obtain a view of the entire heart with one rotation (0.35 s) without requiring the helical method. As such, ADCT is expected to reduce the radiation dose. We studied image quality and radiation dose of ADCT compared to that of 64-MDCT in patients with a low heart rate (HR≤60). Three hundred eighty-five consecutive patients underwent 64-MDCT and 379 patients, ADCT. Patients with an arrhythmia were excluded. Prospective ECG-gated helical scan with high HP (FlashScan) in 64 was used for MDCT and prospective ECG-gated conventional one beat scan, for 320-ADCT. Image quality was visually evaluated by an image quality score. Radiation dose was estimated by DLP (mGy・cm) for 64-MDCT and DLP.e (mGy・cm) for 320-ADCT. Radiation dose of 320-ADCT (208±48 mGy・cm) was significantly (P<0.0001) lower than that of 64-MDCT (484±112 mGy・cm), and image quality score of 320-ADCT (3.0±0.2) was significantly (P=0.0011) higher than that of 64-MDCT (2.9±0.4). Scan time of 320-ADCT (1.4±0.1 s) was also significantly (P<0.0001) shorter than that of 64-MDCT (6.8±0.6 s). 320-ADCT can achieve not only a reduction in radiation dose but also a superior image quality and shortening of scan time compared to 64-MDCT.

  7. Accuracy and effectiveness of self-gating signals in free-breathing three-dimensional cardiac cine magnetic resonance imaging

    International Nuclear Information System (INIS)

    Li Shuo; Gao Song; Wang Lei; Zhu Yan-Chun; Yang Jie; Xie Yao-Qin; Fu Nan; Wang Yi

    2016-01-01

    Conventional multiple breath-hold two-dimensional (2D) balanced steady-state free precession (SSFP) presents many difficulties in cardiac cine magnetic resonance imaging (MRI). Recently, a self-gated free-breathing three-dimensional (3D) SSFP technique has been proposed as an alternative in many studies. However, the accuracy and effectiveness of self-gating signals have been barely studied before. Since self-gating signals are crucially important in image reconstruction, a systematic study of self-gating signals and comparison with external monitored signals are needed.Previously developed self-gated free-breathing 3D SSFP techniques are used on twenty-eight healthy volunteers. Both electrocardiographic (ECG) and respiratory bellow signals are also acquired during the scan as external signals. Self-gating signal and external signal are compared by trigger and gating window. Gating window is proposed to evaluate the accuracy and effectiveness of respiratory self-gating signal. Relative deviation of the trigger and root-mean-square-deviation of the cycle duration are calculated. A two-tailed paired t-test is used to identify the difference between self-gating and external signals. A Wilcoxon signed rank test is used to identify the difference between peak and valley self-gating triggers.The results demonstrate an excellent correlation ( P = 0, R > 0.99) between self-gating and external triggers. Wilcoxon signed rank test shows that there is no significant difference between peak and valley self-gating triggers for both cardiac ( H = 0, P > 0.10) and respiratory ( H = 0, P > 0.44) motions. The difference between self-gating and externally monitored signals is not significant (two-tailed paired-sample t-test: H = 0, P > 0.90).The self-gating signals could demonstrate cardiac and respiratory motion accurately and effectively as ECG and respiratory bellow. The difference between the two methods is not significant and can be explained. Furthermore, few ECG trigger errors

  8. Functional Image-Guided Radiotherapy Planning in Respiratory-Gated Intensity-Modulated Radiotherapy for Lung Cancer Patients With Chronic Obstructive Pulmonary Disease

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Tomoki, E-mail: tkkimura@hiroshima-u.ac.jp [Department of Radiation Oncology, Hiroshima University, Graduate School of Biomedical Sciences, Hiroshima City (Japan); Nishibuchi, Ikuno; Murakami, Yuji; Kenjo, Masahiro; Kaneyasu, Yuko; Nagata, Yasushi [Department of Radiation Oncology, Hiroshima University, Graduate School of Biomedical Sciences, Hiroshima City (Japan)

    2012-03-15

    Purpose: To investigate the incorporation of functional lung image-derived low attenuation area (LAA) based on four-dimensional computed tomography (4D-CT) into respiratory-gated intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) in treatment planning for lung cancer patients with chronic obstructive pulmonary disease (COPD). Methods and Materials: Eight lung cancer patients with COPD were the subjects of this study. LAA was generated from 4D-CT data sets according to CT values of less than than -860 Hounsfield units (HU) as a threshold. The functional lung image was defined as the area where LAA was excluded from the image of the total lung. Two respiratory-gated radiotherapy plans (70 Gy/35 fractions) were designed and compared in each patient as follows: Plan A was an anatomical IMRT or VMAT plan based on the total lung; Plan F was a functional IMRT or VMAT plan based on the functional lung. Dosimetric parameters (percentage of total lung volume irradiated with {>=}20 Gy [V20], and mean dose of total lung [MLD]) of the two plans were compared. Results: V20 was lower in Plan F than in Plan A (mean 1.5%, p = 0.025 in IMRT, mean 1.6%, p = 0.044 in VMAT) achieved by a reduction in MLD (mean 0.23 Gy, p = 0.083 in IMRT, mean 0.5 Gy, p = 0.042 in VMAT). No differences were noted in target volume coverage and organ-at-risk doses. Conclusions: Functional IGRT planning based on LAA in respiratory-guided IMRT or VMAT appears to be effective in preserving a functional lung in lung cancer patients with COPD.

  9. Respiratory gated PET/CT of the liver: A novel method and its impact on the detection of colorectal liver metastases

    International Nuclear Information System (INIS)

    Schulz, Anselm; Godt, Johannes Clemens; Dormagen, Johann Baptist; Holtedahl, Jon Erik; Bogsrud, Trond Velde; Labori, Knut Jørgen; Kløw, Nils-Einar; Bach-Gansmo, Tore

    2015-01-01

    Highlights: • Combined PET/CT and respiratory gated PET/CT improved sensitivity significantly. • Respiratory gated PET/CT had greatest impact on detection of small CRLM <10 mm. • Our results were comparable to earlier reported more complex and expensive methods. • The method used is inexpensive and requires only limited additional imaging time. - Abstract: Purpose: To evaluate the diagnostic performance of a new method for respiratory gated positron emission tomography (rgPET/CT) for colorectal liver metastases (CRLM), secondly, to assess its additional value to standard PET/CT (PET/CT). Materials and methods: Forty-three patients scheduled for resection of suspected CRLM were prospectively included from September 2011 to January 2013. None of the patients had previously undergone treatment for their CRLM. All patients underwent PET/CT and rgPET/CT in the same session. For rgPET/CT an in-house developed electronic circuit was used which displayed a color-coded countdown for the patient. The patients held their breath according to the countdown and only the data from the inspiration breath-hold period was used for image reconstruction. Two independent and blinded readers evaluated both PET/CT and rgPET/CT separately. The reference standard was histopathological confirmation for 73 out of 131 CRLM and follow-up otherwise. Results: Reference standard identified 131 CRLM in 39/43 patients. Nine patients accounted for 25 mucinous CRLM. The overall per-lesion sensitivity for detection of CRLM was for PET/CT 60.0%, for rgPET/CT 63.1%, and for standard + rgPET/CT 67.7%, respectively. Standard + rgPET/CT was overall significantly more sensitive for CRLM compared to PET/CT (p = 0.002) and rgPET/CT (p = 0.031). The overall positive predictive value (PPV) for detection of CRLM was for PET/CT 97.5%, for rgPET/CT 95.3%, and for standard + rgPET/CT 93.6%, respectively. Conclusion: Combination of PET/CT and rgPET/CT improved the sensitivity significantly for CRLM. However

  10. Respiratory gated PET/CT of the liver: A novel method and its impact on the detection of colorectal liver metastases

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Anselm, E-mail: anselm.schulz@gmail.com [Department of Radiology and Nuclear Medicine, Oslo University Hospital, Postboks Pb 4956 Nydalen, 0424 Oslo (Norway); Institute of Clinical Medicine, University of Oslo, P.O. Box 1171 Blindern, 0318 Oslo (Norway); Godt, Johannes Clemens, E-mail: UXGODJ@ous-hf.no [Department of Radiology and Nuclear Medicine, Oslo University Hospital, Postboks Pb 4956 Nydalen, 0424 Oslo (Norway); Institute of Clinical Medicine, University of Oslo, P.O. Box 1171 Blindern, 0318 Oslo (Norway); Dormagen, Johann Baptist, E-mail: UXJORM@ous-hf.no [Department of Radiology and Nuclear Medicine, Oslo University Hospital, Postboks Pb 4956 Nydalen, 0424 Oslo (Norway); Holtedahl, Jon Erik, E-mail: JONHOL@ous-hf.no [The Intervention Centre, Oslo University Hospital, Postboks 4950 Nydalen, 0424 Oslo (Norway); Bogsrud, Trond Velde, E-mail: tvbog@aol.com [Department of Radiology and Nuclear Medicine, Oslo University Hospital, Postboks Pb 4956 Nydalen, 0424 Oslo (Norway); Department of Nuclear Medicine and PET-Center, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C (Denmark); Labori, Knut Jørgen, E-mail: uxknab@ous-hf.no [Department of Hepato-Pancreato-Biliary Surgery, Oslo University Hospital, Postboks 4950 Nydalen, 0424 Oslo (Norway); Kløw, Nils-Einar, E-mail: NILKLO@ous-hf.no [Department of Radiology and Nuclear Medicine, Oslo University Hospital, Postboks Pb 4956 Nydalen, 0424 Oslo (Norway); Institute of Clinical Medicine, University of Oslo, P.O. Box 1171 Blindern, 0318 Oslo (Norway); Bach-Gansmo, Tore, E-mail: bat@ous-hf.no [Department of Radiology and Nuclear Medicine, Oslo University Hospital, Postboks Pb 4956 Nydalen, 0424 Oslo (Norway)

    2015-08-15

    Highlights: • Combined PET/CT and respiratory gated PET/CT improved sensitivity significantly. • Respiratory gated PET/CT had greatest impact on detection of small CRLM <10 mm. • Our results were comparable to earlier reported more complex and expensive methods. • The method used is inexpensive and requires only limited additional imaging time. - Abstract: Purpose: To evaluate the diagnostic performance of a new method for respiratory gated positron emission tomography (rgPET/CT) for colorectal liver metastases (CRLM), secondly, to assess its additional value to standard PET/CT (PET/CT). Materials and methods: Forty-three patients scheduled for resection of suspected CRLM were prospectively included from September 2011 to January 2013. None of the patients had previously undergone treatment for their CRLM. All patients underwent PET/CT and rgPET/CT in the same session. For rgPET/CT an in-house developed electronic circuit was used which displayed a color-coded countdown for the patient. The patients held their breath according to the countdown and only the data from the inspiration breath-hold period was used for image reconstruction. Two independent and blinded readers evaluated both PET/CT and rgPET/CT separately. The reference standard was histopathological confirmation for 73 out of 131 CRLM and follow-up otherwise. Results: Reference standard identified 131 CRLM in 39/43 patients. Nine patients accounted for 25 mucinous CRLM. The overall per-lesion sensitivity for detection of CRLM was for PET/CT 60.0%, for rgPET/CT 63.1%, and for standard + rgPET/CT 67.7%, respectively. Standard + rgPET/CT was overall significantly more sensitive for CRLM compared to PET/CT (p = 0.002) and rgPET/CT (p = 0.031). The overall positive predictive value (PPV) for detection of CRLM was for PET/CT 97.5%, for rgPET/CT 95.3%, and for standard + rgPET/CT 93.6%, respectively. Conclusion: Combination of PET/CT and rgPET/CT improved the sensitivity significantly for CRLM. However

  11. Respiratory synchronization for lung tumors exploration by positon emission tomography

    International Nuclear Information System (INIS)

    Grotus, Nicolas

    2009-01-01

    Positron Emission Tomography (PET) is a medical imaging technique that requires several minutes of acquisition to get an image. PET images are thus severely affected by the respiratory motion of the patient, which introduces a blur in the images. Techniques consisting in gating the PET acquisition as a function of the patient respiration exist and reduce the respiratory blur in the PET images. However, these techniques increase the noise in the reconstructed images. The aim of this work was to propose a method for respiratory motion compensation that would not enhance the noise in the PET images, without increasing the acquisition duration nor estimating the deformation field associated with the respiratory motion. We proposed 2 original spatio-temporal (4D) reconstruction algorithms of gated PET images. These 2 methods take advantage of the temporal correlation between the images corresponding to the different breathing phases. The performances of these techniques were evaluated and compared to classic approaches using phantom data and simulated data. The results showed that the 4D reconstructions increase the signal-to-noise ratio compared to the classic reconstructions while maintaining the reduction of the respiratory blur. For a fixed acquisition duration, the 4D reconstructions can thus yield gated images that are almost free of respiratory blur and of the same quality in terms of noise level as the ones obtained without respiratory gating. The clinical feasibility of the proposed techniques was also demonstrated. (author) [fr

  12. Clinical validation of free breathing respiratory triggered retrospectively cardiac gated cine balanced steady-state free precession cardiovascular magnetic resonance in sedated children

    OpenAIRE

    Krishnamurthy, Rajesh; Pednekar, Amol; Atweh, Lamya A; Vogelius, Esben; Chu, Zili David; Zhang, Wei; Maskatia, Shiraz; Masand, Prakash; Morris, Shaine A; Krishnamurthy, Ramkumar; Muthupillai, Raja

    2015-01-01

    Background Cine balanced steady-state free precession (SSFP), the preferred sequence for ventricular function, demands uninterrupted radio frequency (RF) excitation to maintain the steady-state during suspended respiration. This is difficult to accomplish in sedated children. In this work, we validate a respiratory triggered (RT) SSFP sequence that drives the magnetization to steady-state before commencing retrospectively cardiac gated cine acquisition in a sedated pediatric population. Metho...

  13. Data acquisition for experiments with multi-detector arrays

    Indian Academy of Sciences (India)

    Experiments with multi-detector arrays have special requirements and place higher demands on computer data acquisition systems. In this contribution we discuss data acquisition systems with special emphasis on multi-detector arrays and in particular we describe a new data acquisition system, AMPS which we have ...

  14. SU-E-T-350: Verification of Gating Performance of a New Elekta Gating Solution: Response Kit and Catalyst System

    Energy Technology Data Exchange (ETDEWEB)

    Xie, X; Cao, D; Housley, D; Mehta, V; Shepard, D [Swedish Cancer Institute, Seattle, WA (United States)

    2014-06-01

    Purpose: In this work, we have tested the performance of new respiratory gating solutions for Elekta linacs. These solutions include the Response gating and the C-RAD Catalyst surface mapping system.Verification measurements have been performed for a series of clinical cases. We also examined the beam on latency of the system and its impact on delivery efficiency. Methods: To verify the benefits of tighter gating windows, a Quasar Respiratory Motion Platform was used. Its vertical-motion plate acted as a respiration surrogate and was tracked by the Catalyst system to generate gating signals. A MatriXX ion-chamber array was mounted on its longitudinal-moving platform. Clinical plans are delivered to a stationary and moving Matrix array at 100%, 50% and 30% gating windows and gamma scores were calculated comparing moving delivery results to the stationary result. It is important to note that as one moves to tighter gating windows, the delivery efficiency will be impacted by the linac's beam-on latency. Using a specialized software package, we generated beam-on signals of lengths of 1000ms, 600ms, 450ms, 400ms, 350ms and 300ms. As the gating windows get tighter, one can expect to reach a point where the dose rate will fall to nearly zero, indicating that the gating window is close to beam-on latency. A clinically useful gating window needs to be significantly longer than the latency for the linac. Results: As expected, the use of tighter gating windows improved delivery accuracy. However, a lower limit of the gating window, largely defined by linac beam-on latency, exists at around 300ms. Conclusion: The Response gating kit, combined with the C-RAD Catalyst, provides an effective solution for respiratorygated treatment delivery. Careful patient selection, gating window design, even visual/audio coaching may be necessary to ensure both delivery quality and efficiency. This research project is funded by Elekta.

  15. Dual-gated volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Fahimian, Benjamin; Wu, Junqing; Wu, Huanmei; Geneser, Sarah; Xing, Lei

    2014-01-01

    Gated Volumetric Modulated Arc Therapy (VMAT) is an emerging radiation therapy modality for treatment of tumors affected by respiratory motion. However, gating significantly prolongs the treatment time, as delivery is only activated during a single respiratory phase. To enhance the efficiency of gated VMAT delivery, a novel dual-gated VMAT (DG-VMAT) technique, in which delivery is executed at both exhale and inhale phases in a given arc rotation, is developed and experimentally evaluated. Arc delivery at two phases is realized by sequentially interleaving control points consisting of MUs, MLC sequences, and angles of VMAT plans generated at the exhale and inhale phases. Dual-gated delivery is initiated when a respiration gating signal enters the exhale window; when the exhale delivery concludes, the beam turns off and the gantry rolls back to the starting position for the inhale window. The process is then repeated until both inhale and exhale arcs are fully delivered. DG-VMAT plan delivery accuracy was assessed using a pinpoint chamber and diode array phantom undergoing programmed motion. DG-VMAT delivery was experimentally implemented through custom XML scripting in Varian’s TrueBeam™ STx Developer Mode. Relative to single gated delivery at exhale, the treatment time was improved by 95.5% for a sinusoidal breathing pattern. The pinpoint chamber dose measurement agreed with the calculated dose within 0.7%. For the DG-VMAT delivery, 97.5% of the diode array measurements passed the 3%/3 mm gamma criterion. The feasibility of DG-VMAT delivery scheme has been experimentally demonstrated for the first time. By leveraging the stability and natural pauses that occur at end-inspiration and end-exhalation, DG-VMAT provides a practical method for enhancing gated delivery efficiency by up to a factor of two

  16. The correlation between internal and external markers for abdominal tumors: Implications for respiratory gating

    International Nuclear Information System (INIS)

    Gierga, David P.; Brewer, Johanna; Sharp, Gregory C.; Betke, Margrit; Willett, Christopher G.; Chen, George T.Y.

    2005-01-01

    Purpose: The correlation of the respiratory motion of external patient markers and abdominal tumors was examined. Data of this type are important for image-guided therapy techniques, such as respiratory gating, that monitor the movement of external fiducials. Methods and Materials: Fluoroscopy sessions for 4 patients with internal, radiopaque tumor fiducial clips were analyzed by computer vision techniques. The motion of the internal clips and the external markers placed on the patient's abdominal skin surface were quantified and correlated. Results: In general, the motion of the tumor and external markers were well correlated. The maximum amount of peak-to-peak craniocaudal tumor motion was 2.5 cm. The ratio of tumor motion to external-marker motion ranged from 0.85 to 7.1. The variation in tumor position for a given external-marker position ranged from 2 to 9 mm. The period of the breathing cycle ranged from 2.7 to 4.5 seconds, and the frequency patterns for both the tumor and the external markers were similar. Conclusions: Although tumor motion generally correlated well with external fiducial marker motion, relatively large underlying tumor motion can occur compared with external-marker motion and variations in the tumor position for a given marker position. Treatment margins should be determined on the basis of a detailed understanding of tumor motion, as opposed to relying only on external-marker information

  17. Step-and-shoot prospectively ECG-gated vs. retrospectively ECG-gated with tube current modulation coronary CT angiography using 128-slice MDCT patients with chest pain: diagnostic performance and radiation dose

    International Nuclear Information System (INIS)

    Kim, Jeong Su; Choo, Ki Seok; Jeong, Dong Wook

    2011-01-01

    Background With increasing awareness for radiation exposure, the study of diagnostic accuracy of coronary CT angiography (CCTA) with low radiation dose techniques is mandatory to both radiologist and clinician. Purpose To compare diagnostic performance and effective radiation dose between step-and-shoot prospectively ECG-gated and retrospectively ECG-gated with tube current modulation (TCM) CCTA using 128-slice multidetector computed tomography (MDCT). Material and Methods We retrospectively evaluated 60 patients who underwent CCTA with either of two different low-dose techniques using 128-slice MDCT (23 patients for step-and shoot-prospectively ECG-gated and 37 patients for retrospectively ECG-gated with TCM CCTA) followed by conventional coronary angiography. All coronary arteries and all segments thereof, except anatomical variants or small size (< 1.5 mm) ones, were included in analysis. Results In per-segment analysis, sensitivity, specificity, positive predictive value, and negative predictive value were 91/96%, 95/94%, 75/73%, and 98/99% for step-and-shoot prospectively ECG-gated and retrospectively ECG gated with TCM CCTA, respectively, relative to conventional coronary angiography. Effective radiation dose were 1.75 ± 0.83 mSv, 4.91 ± 1.71 mSv in the step-and-shoot prospectively ECG-gated and retrospectively ECG-gated with TCM CCTA groups, respectively. Conclusion The two low-radiation dose CCTA techniques using 128-slice MDCT yields comparable diagnostic performance for coronary artery disease in symptomatic patients with low heart rates

  18. A Prospective Cohort Study of Gated Stereotactic Liver Radiation Therapy Using Continuous Internal Electromagnetic Motion Monitoring

    DEFF Research Database (Denmark)

    Worm, Esben S; Høyer, Morten; Hansen, Rune

    2018-01-01

    PURPOSE: Intrafraction motion can compromise the treatment accuracy in liver stereotactic body radiation therapy (SBRT). Respiratory gating can improve treatment delivery; however, gating based on external motion surrogates is inaccurate. The present study reports the use of Calypso-based internal...... electromagnetic motion monitoring for gated liver SBRT. METHODS AND MATERIALS: Fifteen patients were included in a study of 3-fraction respiratory gated liver SBRT guided by 3 implanted electromagnetic transponders. The planning target volume was created by a 5-mm axial and 7-mm (n = 12) or 10-mm (n = 3...

  19. Enhancing ejection fraction measurement through 4D respiratory motion compensation in cardiac PET imaging

    Science.gov (United States)

    Tang, Jing; Wang, Xinhui; Gao, Xiangzhen; Segars, W. Paul; Lodge, Martin A.; Rahmim, Arman

    2017-06-01

    ECG gated cardiac PET imaging measures functional parameters such as left ventricle (LV) ejection fraction (EF), providing diagnostic and prognostic information for management of patients with coronary artery disease (CAD). Respiratory motion degrades spatial resolution and affects the accuracy in measuring the LV volumes for EF calculation. The goal of this study is to systematically investigate the effect of respiratory motion correction on the estimation of end-diastolic volume (EDV), end-systolic volume (ESV), and EF, especially on the separation of normal and abnormal EFs. We developed a respiratory motion incorporated 4D PET image reconstruction technique which uses all gated-frame data to acquire a motion-suppressed image. Using the standard XCAT phantom and two individual-specific volunteer XCAT phantoms, we simulated dual-gated myocardial perfusion imaging data for normally and abnormally beating hearts. With and without respiratory motion correction, we measured the EDV, ESV, and EF from the cardiac-gated reconstructed images. For all the phantoms, the estimated volumes increased and the biases significantly reduced with motion correction compared with those without. Furthermore, the improvement of ESV measurement in the abnormally beating heart led to better separation of normal and abnormal EFs. The simulation study demonstrated the significant effect of respiratory motion correction on cardiac imaging data with motion amplitude as small as 0.7 cm. The larger the motion amplitude the more improvement respiratory motion correction brought about on the EF measurement. Using data-driven respiratory gating, we also demonstrated the effect of respiratory motion correction on estimating the above functional parameters from list mode patient data. Respiratory motion correction has been shown to improve the accuracy of EF measurement in clinical cardiac PET imaging.

  20. The Impact of Optimal Respiratory Gating and Image Noise on Evaluation of Intratumor Heterogeneity on 18F-FDG PET Imaging of Lung Cancer.

    Science.gov (United States)

    Grootjans, Willem; Tixier, Florent; van der Vos, Charlotte S; Vriens, Dennis; Le Rest, Catherine C; Bussink, Johan; Oyen, Wim J G; de Geus-Oei, Lioe-Fee; Visvikis, Dimitris; Visser, Eric P

    2016-11-01

    Accurate measurement of intratumor heterogeneity using parameters of texture on PET images is essential for precise characterization of cancer lesions. In this study, we investigated the influence of respiratory motion and varying noise levels on quantification of textural parameters in patients with lung cancer. We used an optimal-respiratory-gating algorithm on the list-mode data of 60 lung cancer patients who underwent 18 F-FDG PET. The images were reconstructed using a duty cycle of 35% (percentage of the total acquired PET data). In addition, nongated images of varying statistical quality (using 35% and 100% of the PET data) were reconstructed to investigate the effects of image noise. Several global image-derived indices and textural parameters (entropy, high-intensity emphasis, zone percentage, and dissimilarity) that have been associated with patient outcome were calculated. The clinical impact of optimal respiratory gating and image noise on assessment of intratumor heterogeneity was evaluated using Cox regression models, with overall survival as the outcome measure. The threshold for statistical significance was adjusted for multiple comparisons using Bonferroni correction. In the lower lung lobes, respiratory motion significantly affected quantification of intratumor heterogeneity for all textural parameters (P 0.007). The mean increase in entropy, dissimilarity, zone percentage, and high-intensity emphasis was 1.3% ± 1.5% (P = 0.02), 11.6% ± 11.8% (P = 0.006), 2.3% ± 2.2% (P = 0.002), and 16.8% ± 17.2% (P = 0.006), respectively. No significant differences were observed for lesions in the upper lung lobes (P > 0.007). Differences in the statistical quality of the PET images affected the textural parameters less than respiratory motion, with no significant difference observed. The median follow-up time was 35 mo (range, 7-39 mo). In multivariate analysis for overall survival, total lesion glycolysis and high-intensity emphasis were the two most

  1. Sacroiliitis in Ankylosing Spondylitis: Comparison with Multidetector Row CT and Plain Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ji Youn; Joo, Kyung Bin; Choi, Byeong Kyoo; Ryu, Jeong Ah; Kim, Tae Hwan; Choi, Woo Jung [Hanyang University Hospital, Seoul (Korea, Republic of)

    2009-03-15

    The objective of our study was to compare multidetector row CT and the plain radiographs for making the diagnosis and grading the sacroiliitis that accompanies ankylosing spondylitis. We wanted to determine the role of multidetector row CT for the evaluation of the sacroilitis in patients with ankylosing spondylitis. One hundred ninety two patients with clinically suspected ankylosing spondylitis were evaluated by conventional radiography and multidetector row CT. Two musculoskeletal radiologists retrospectively analyzed the images, and they graded the sacroiliitis using the modified New York Criteria. Multidetector row CT demonstrated a significantly higher sensitivity (74.5%, 83.3%) than did plain radiography (59.9%, 66.7%) for detecting early sacroiliitis (p<0.05). Multidetector row CT showed a higher grade of sacroiliitis in 114 and 127 of 384 sacroiliac joints. Performing multidetector row CT rather than plain radiography for making the diagnoses of accompanying ankylosing spondylitis allows an early start of treatment with a subsequently improved prognosis

  2. Self-gated golden-angle spiral 4D flow MRI.

    Science.gov (United States)

    Bastkowski, Rene; Weiss, Kilian; Maintz, David; Giese, Daniel

    2018-01-17

    The acquisition of 4D flow magnetic resonance imaging (MRI) in cardiovascular applications has recently made large progress toward clinical feasibility. The need for simultaneous compensation of cardiac and breathing motion still poses a challenge for widespread clinical use. Especially, breathing motion, addressed by gating approaches, can lead to unpredictable and long scan times. The current work proposes a time-efficient self-gated 4D flow sequence that exploits up to 100% of the acquired data and operates at a predictable scan time. A self-gated golden-angle spiral 4D flow sequence was implemented and tested in 10 volunteers. Data were retrospectively binned into respiratory and cardiac states and reconstructed using a conjugate-gradient sensitivity encoding reconstruction. Net flow curves, stroke volumes, and peak flow in the aorta were evaluated and compared to a conventional Cartesian 4D flow sequence. Additionally, flow quantities reconstructed from 50% to 100% of the self-gated 4D flow data were compared. Self-gating signals for respiratory and cardiac motion were extracted for all volunteers. Flow quantities were in agreement with the standard Cartesian scan. Mean differences in stroke volumes and peak flow of 7.6 ± 11.5 and 4.0 ± 79.9 mL/s were obtained, respectively. By retrospectively increasing breathing navigator efficiency while decreasing acquisition times (15:06-07:33 minutes), 50% of the acquired data were sufficient to measure stroke volumes with errors under 9.6 mL. The feasibility to acquire respiratory and cardiac self-gated 4D flow data at a predictable scan time was demonstrated. Magn Reson Med, 2018. © 2018 International Society for Magnetic Resonance in Medicine. © 2018 International Society for Magnetic Resonance in Medicine.

  3. Evaluation of accuracy about 2D vs 3D real-time position management system based on couch rotation when non-coplanar respiratory gated radiation therapy

    International Nuclear Information System (INIS)

    Kwon, Kyung Tae; Kim, Jung Soo; Sim, Hyun Sun; Min, Jung Whan; Son, Soon Yong; Han, Dong Kyoon

    2016-01-01

    Because of non-coplanar therapy with couch rotation in respiratory gated radiation therapy, the recognition of marker movement due to the change in the distance between the infrared camera and the marker due to the rotation of the couch is called RPM (Real-time The purpose of this paper is to evaluate the accuracy of motion reflections (baseline changes) of 2D gating configuration (two dot marker block) and 3D gating configuration (six dot marker block). The motion was measured by varying the couch angle in the clockwise and counterclockwise directions by 10° in the 2D gating configuration. In the 3D gating configuration, the couch angle was changed by 10° in the clockwise direction and compared with the baseline at the reference 0°. The reference amplitude was 1.173 to 1.165, the couch angle at 20° was 1.132, and the couch angle at 1.0° was 1.083. At 350° counterclockwise, the reference amplitude was 1.168 to 1.157, the couch angle at 340° was 1.124, and the couch angle at 330° was 1.079. In this study, the phantom is used to quantitatively evaluate the value of the amplitude according to couch change

  4. Evaluation of accuracy about 2D vs 3D real-time position management system based on couch rotation when non-coplanar respiratory gated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kyung Tae; Kim, Jung Soo [Dongnam Health University, Suwon (Korea, Republic of); Sim, Hyun Sun [College of Health Sciences, Korea University, Seoul (Korea, Republic of); Min, Jung Whan [Shingu University College, Sungnam (Korea, Republic of); Son, Soon Yong [Wonkwang Health Science University, Iksan (Korea, Republic of); Han, Dong Kyoon [College of Health Sciences, EulJi University, Daejeon (Korea, Republic of)

    2016-12-15

    Because of non-coplanar therapy with couch rotation in respiratory gated radiation therapy, the recognition of marker movement due to the change in the distance between the infrared camera and the marker due to the rotation of the couch is called RPM (Real-time The purpose of this paper is to evaluate the accuracy of motion reflections (baseline changes) of 2D gating configuration (two dot marker block) and 3D gating configuration (six dot marker block). The motion was measured by varying the couch angle in the clockwise and counterclockwise directions by 10° in the 2D gating configuration. In the 3D gating configuration, the couch angle was changed by 10° in the clockwise direction and compared with the baseline at the reference 0°. The reference amplitude was 1.173 to 1.165, the couch angle at 20° was 1.132, and the couch angle at 1.0° was 1.083. At 350° counterclockwise, the reference amplitude was 1.168 to 1.157, the couch angle at 340° was 1.124, and the couch angle at 330° was 1.079. In this study, the phantom is used to quantitatively evaluate the value of the amplitude according to couch change.

  5. Main technical aspects and clinical benefits of respiratory Gating for radiotherapy of lung neoplasm; Principais aspectos tecnicos e beneficios clinicos do Gating respitatorio para radioterapia do cancer de pulmao

    Energy Technology Data Exchange (ETDEWEB)

    Benites, Rafaela Freitas Oliveira, E-mail: rafaelafreitasfisica@gmail.com [Fundacao do Cancer, Rio de Janeiro, RJ (Brazil)

    2016-07-01

    The concern with the irradiation of lung tumors is that many of them can move along the breathing, which can cause problems in defining accurately the target and increases the irradiation of normal tissues. The objectives are to present the 4D CT principles, image acquisition, reconstruction and application in planning of the radiotherapy. It justifies the quick implantation, improvements in acquisition and images, the possibility in quantify the tumor movement, verifying strategies and delivery treatment. It's concluded that the toxicity risk is reduced with the respiratory gating, and the results suggests that the closed RT will be of clinical relevance. (author)

  6. Multidetector CT evaluation of potential right lobe living donors for ...

    African Journals Online (AJOL)

    Mohamed Saied Abdelgawad

    Multidetector CT evaluation of potential right lobe living donors for liver transplantation. Mohamed Saied Abdelgawad *, Osama L. El-Abd. National Liver Institute, El-Menoufiya University, Shebein El-Koom, Alexandria, Egypt. Received 4 June 2011; accepted 18 June 2011. KEYWORDS. Liver transplantation;. Multidetector ...

  7. Accuracy and effectiveness of self-gating signals in free-breathing three-dimensional cardiac cine magnetic resonance imaging

    Science.gov (United States)

    Li, Shuo; Wang, Lei; Zhu, Yan-Chun; Yang, Jie; Xie, Yao-Qin; Fu, Nan; Wang, Yi; Gao, Song

    2016-12-01

    Conventional multiple breath-hold two-dimensional (2D) balanced steady-state free precession (SSFP) presents many difficulties in cardiac cine magnetic resonance imaging (MRI). Recently, a self-gated free-breathing three-dimensional (3D) SSFP technique has been proposed as an alternative in many studies. However, the accuracy and effectiveness of self-gating signals have been barely studied before. Since self-gating signals are crucially important in image reconstruction, a systematic study of self-gating signals and comparison with external monitored signals are needed. Previously developed self-gated free-breathing 3D SSFP techniques are used on twenty-eight healthy volunteers. Both electrocardiographic (ECG) and respiratory bellow signals are also acquired during the scan as external signals. Self-gating signal and external signal are compared by trigger and gating window. Gating window is proposed to evaluate the accuracy and effectiveness of respiratory self-gating signal. Relative deviation of the trigger and root-mean-square-deviation of the cycle duration are calculated. A two-tailed paired t-test is used to identify the difference between self-gating and external signals. A Wilcoxon signed rank test is used to identify the difference between peak and valley self-gating triggers. The results demonstrate an excellent correlation (P = 0, R > 0.99) between self-gating and external triggers. Wilcoxon signed rank test shows that there is no significant difference between peak and valley self-gating triggers for both cardiac (H = 0, P > 0.10) and respiratory (H = 0, P > 0.44) motions. The difference between self-gating and externally monitored signals is not significant (two-tailed paired-sample t-test: H = 0, P > 0.90). The self-gating signals could demonstrate cardiac and respiratory motion accurately and effectively as ECG and respiratory bellow. The difference between the two methods is not significant and can be explained. Furthermore, few ECG trigger errors

  8. Respiratory Motion Management in PET/CT: Applications and Clinical Usefulness.

    Science.gov (United States)

    Guerra, Luca; Ponti, Elena De; Morzenti, Sabrina; Spadavecchia, Chiara; Crivellaro, Cinzia

    2017-01-01

    Breathing movement can introduce heavy bias in both image quality and quantitation in PET/CT. The aim of this paper is a review of the literature to evaluate the benefit of respiratory gating in terms of image quality, quantification and lesion detectability. A review of the literature published in the last 10 years and dealing with gated PET/CT technique has been performed, focusing on improvement in quantification, lesion detectability and diagnostic accuracy in neoplastic lesion. In addition, the improvement in the definition of radiotherapy planning has been evaluated. There is a consistent increase of the Standardized Uptake Value (SUV) in gated PET images when compared to ungated ones, particularly for lesions located in liver and in lung. Respiratory gating can also increase sensitivity, specificity and accuracy of PET/CT. Gated PET/CT can be used for radiation therapy planning, reducing the uncertainty in target definition, optimizing the volume to be treated and reducing the possibility of "missing" during the dose delivery. Moreover, new technologies, able to define the movement of lesions and organs directly from the PET sinogram, can solve some problems that currently are limiting the clinical use of gated PET/CT (i.e.: extended acquisition time, radiation exposure). The published literature demonstrated that respiratory gating PET/CT is a valid technique to improve quantification, lesion detectability of lung and liver tumors and can better define the radiotherapy planning of moving lesions and organs. If new technical improvements for motion compensation will be clinically validated, gated technique could be applied routinely in any PET/CT scan. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. Patent foramen ovale: diagnosis with multidetector CT--comparison with transesophageal echocardiography.

    Science.gov (United States)

    Kim, Young Jin; Hur, Jin; Shim, Chi-Young; Lee, Hye-Jeong; Ha, Jong-Won; Choe, Kyu Ok; Heo, Ji Hoe; Choi, Eui-Young; Choi, Byoung Wook

    2009-01-01

    To evaluate the clinical feasibility and accuracy of 64-section multidetector computed tomography (CT) compared with transesophageal echocardiography (TEE) for diagnosis of a patent foramen ovale (PFO). Institutional review board approval was obtained for this retrospective study. The study included 152 consecutive stroke patients (mean age, 61.7 years; 98 men, 54 women) who underwent both cardiac multidetector CT and TEE. Electrocardiographically gated cardiac CT was performed with a 64-section CT scanner by using a saline-chaser contrast agent injection technique. A contrast agent jet from the contrast agent-filled left atrium (LA) to the saline-filled right atrium (RA) and channel-like appearance of the interatrial septum (IAS) were evaluated on axial and oblique sagittal CT images. Two-dimensional and Doppler TEE were performed to detect PFO. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT were obtained with TEE as the reference standard. A PFO was present in 26 patients at TEE. On CT images, a left-to-right contrast agent jet toward the inferior vena cava was noted in 21 patients (sensitivity, 73.1%; specificity, 98.4%; PPV, 90.5%; NPV, 94.7%). Channel-like appearance of the IAS was detected in 38 patients (sensitivity, 76.9%; specificity, 85.7%; PPV, 52.6%; NPV, 94.7%). Channel-like appearance of the IAS was noted in all patients who had a contrast agent jet. A contrast agent jet from LA to RA toward the inferior vena cava with channel-like appearance of the IAS on CT images confirms the presence of a PFO. (c) RSNA, 2008.

  10. MO-FG-BRA-03: A Novel Method for Characterizing Gating Response Time in Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Wiersma, R; McCabe, B; Belcher, A; Jenson, P [The University of Chicago, Chicago, IL (United States); Smith, B [University Illinois at Chicago, Orland Park, IL (United States); Aydogan, B [The University of Chicago, Chicago, IL (United States); University Illinois at Chicago, Orland Park, IL (United States)

    2016-06-15

    Purpose: Low temporal latency between a gating ON/OFF signal and the LINAC beam ON/OFF during respiratory gating is critical for patient safety. Current film based methods to assess gating response have poor temporal resolution and are highly qualitative. We describe a novel method to precisely measure gating lag times at high temporal resolutions and use it to characterize the temporal response of several gating systems. Methods: A respiratory gating simulator with an oscillating platform was modified to include a linear potentiometer for position measurement. A photon diode was placed at linear accelerator isocenter for beam output measurement. The output signals of the potentiometer and diode were recorded simultaneously at 2500 Hz (0.4 millisecond (ms) sampling interval) with an analogue-to-digital converter (ADC). The techniques was used on three commercial respiratory gating systems. The ON and OFF of the beam signal were located and compared to the expected gating window for both phase and position based gating and the temporal lag times extracted using a polynomial fit method. Results: A Varian RPM system with a monoscopic IR camera was measured to have mean beam ON and OFF lag times of 98.2 ms and 89.6 ms, respectively. A Varian RPM system with a stereoscopic IR camera was measured to have mean beam ON and OFF lag times of 86.0 ms and 44.0 ms, respectively. A Calypso magnetic fiducial tracking system was measured to have mean beam ON and OFF lag times of 209.0 ms and 60.0 ms, respectively. Conclusions: A novel method allowed for quantitative determination of gating timing accuracy for several clinically used gating systems. All gating systems met the 100 ms TG-142 criteria for mean beam OFF times. For beam ON response, the Calypso system exceeded the recommended response time.

  11. Initial clinical results for breath-hold CT-based processing of respiratory-gated PET acquisitions

    International Nuclear Information System (INIS)

    Fin, Loic; Daouk, Joel; Morvan, Julie; Esper, Isabelle El; Saidi, Lazhar; Meyer, Marc-Etienne; Bailly, Pascal

    2008-01-01

    Respiratory motion causes uptake in positron emission tomography (PET) images of chest structures to spread out and misregister with the CT images. This misregistration can alter the attenuation correction and thus the quantisation of PET images. In this paper, we present the first clinical results for a respiratory-gated PET (RG-PET) processing method based on a single breath-hold CT (BH-CT) acquisition, which seeks to improve diagnostic accuracy via better PET-to-CT co-registration. We refer to this method as ''CT-based'' RG-PET processing. Thirteen lesions were studied. Patients underwent a standard clinical PET protocol and then the CT-based protocol, which consists of a 10-min List Mode RG-PET acquisition, followed by a shallow end-expiration BH-CT. The respective performances of the CT-based and clinical PET methods were evaluated by comparing the distances between the lesions' centroids on PET and CT images. SUV MAX and volume variations were also investigated. The CT-based method showed significantly lower (p=0.027) centroid distances (mean change relative to the clinical method =-49%; range =-100% to 0%). This led to higher SUV MAX (mean change =+33%; range =-4% to 69%). Lesion volumes were significantly lower (p=0.022) in CT-based PET volumes (mean change =-39%: range =-74% to -1%) compared with clinical ones. A CT-based RG-PET processing method can be implemented in clinical practice with a small increase in radiation exposure. It improves PET-CT co-registration of lung lesions and should lead to more accurate attenuation correction and thus SUV measurement. (orig.)

  12. Myocardial perfusion with multi-detector computed tomography: quantitative evaluation

    International Nuclear Information System (INIS)

    Carrascosa, Patricia M.; Vallejos, J.; Capunay, Carlos M.; Deviggiano, A.; Carrascosa, Jorge M.

    2007-01-01

    The objective of this work is to evaluate the skill of multidetector computer tomography, to quantify the different patterns of intensification during the evaluation of the myocardial perfusion. 45 patients were studied with suspicion of cardiovascular disease. Multi-detector computed tomography was utilized on patients at rest and in effort with pharmacological stress, after the administration of dipyridamole. Also they were evaluated using nuclear medicine [es

  13. Multi-detector CT knee arthrography - initial experience

    International Nuclear Information System (INIS)

    Thomson, J.M.Z.; Fallon, M.; Breidahl, W.H.

    2002-01-01

    Full text: Traditional plain film arthrography can achieve reasonable accuracy and is an accepted method of investigation of patients with knee pain and possible meniscal tear. Multi-detector CT can potentially provide a more detailed and accurate examination due to its high-resolution crosssectional and multi-planar capabilities. The aim of this study was to assess the accuracy of our technique. All patients who underwent a multi-detector CT knee arthrogram in an initial 8 month period were identified. Initially the referring clinician was contacted. If the patient was referred to an orthopaedic surgeon the outcome of orthopaedic review was recorded using clinical, arthroscopic and / or MRI follow-up of the patient population. One hundred and twelve patients had a Multi-detector CT knee arthrogram performed within and 8 month period. Follow-up information was received in 69.7% of patients. Of these 68.9% had orthopaedic assessment - of which 69.2% underwent a knee arthroscopy.There was total agreement of findings in 67%, agreement of meniscal findings in 67% and chondral findings in 100%. Overall, orthopaedic opinion agreed with CT findings in 76.9%. At this stage, all meniscal tears not described in the initial CT arthrogram report have in retrospect been visible. Multi-detector CT knee arthrography is an accurate and elegant technique for investigation of knee pain, providing information in a format familiar to those reporting knee MRI. There is an initial learning curve. The technique is particularly useful in chondral assessment. It is accurate for meniscal pathology, although caution and recognition of potential pitfalls is required. Copyright (2002) Blackwell Science Pty Ltd

  14. Free-breathing steady-state free precession cine cardiac magnetic resonance with respiratory navigator gating.

    Science.gov (United States)

    Moghari, Mehdi H; Komarlu, Rukmini; Annese, David; Geva, Tal; Powell, Andrew J

    2015-04-01

    To develop and validate a respiratory motion compensation method for free-breathing cardiac cine imaging. A free-breathing navigator-gated cine steady-state free precession acquisition (Cine-Nav) was developed which preserves the equilibrium state of the net magnetization vector, maintains the high spatial and temporal resolutions of standard breath-hold (BH) acquisition, and images entire cardiac cycle. Cine image data is accepted only from cardiac cycles occurring entirely during end-expiration. Prospective validation was performed in 10 patients by obtaining in each three complete ventricular image stacks with different respiratory motion compensation approaches: (1) BH, (2) free-breathing with 3 signal averages (3AVG), and (3) free-breathing with Cine-Nav. The subjective image quality score (1 = worst, 4 = best) for Cine-Nav (3.8 ± 0.4) was significantly better than for 3AVG (2.2 ± 0.5, P = 0.002), and similar to BH (4.0 ± 0.0, P = 0.13). The blood-to-myocardium contrast ratio for Cine-Nav (6.3 ± 1.5) was similar to BH (5.9 ± 1.6, P = 0.52) and to 3AVG (5.6 ± 2.5, P = 0.43). There were no significant differences between Cine-Nav and BH for the ventricular volumes and mass. In contrast, there were significant differences between 3AVG and BH in all of these measurements but right ventricular mass. Free-breathing cine imaging with Cine-Nav yielded comparable image quality and ventricular measurements to BH, and was superior to 3AVG. © 2014 Wiley Periodicals, Inc.

  15. Statistical analysis of target motion in gated lung stereotactic body radiation therapy

    International Nuclear Information System (INIS)

    Zhao Bo; Yang Yong; Li Tianfang; Li Xiang; Heron, Dwight E; Huq, M Saiful

    2011-01-01

    An external surrogate-based respiratory gating technique is a useful method to reduce target margins for the treatment of a moving lung tumor. The success of this technique relies on a good correlation between the motion of the external markers and the internal tumor as well as the repeatability of the respiratory motion. In gated lung stereotactic body radiation therapy (SBRT), the treatment time for each fraction could exceed 30 min due to large fractional dose. Tumor motion may experience pattern changes such as baseline shift during such extended treatment time. The purpose of this study is to analyze tumor motion traces in actual treatment situations and to evaluate the effect of the target baseline shift in gated lung SBRT treatment. Real-time motion data for both the external markers and tumors from 51 lung SBRT treatments with Cyberknife Synchrony technology were analyzed in this study. The treatment time is typically greater than 30 min. The baseline shift was calculated with a rolling average window equivalent to ∼20 s and subtracted from that at the beginning. The magnitude of the baseline shift and its relationship with treatment time were investigated. Phase gating simulation was retrospectively performed on 12 carefully selected treatments with respiratory amplitude larger than 5 mm and regular phases. A customized gating window was defined for each individual treatment. It was found that the baseline shifts are specific to each patient and each fraction. Statistical analysis revealed that more than 69% treatments exhibited increased baseline shifts with the lapse of treatment time. The magnitude of the baseline shift could reach 5.3 mm during a 30 min treatment. Gating simulation showed that tumor excursion was caused mainly by the uncertainties in phase gating simulation and baseline shift, the latter being the primary factor. With a 5 mm gating window, 2 out of 12 treatments in the study group showed significant tumor excursion. Baseline shifts

  16. Fabrication process of ionization chamber multidetector and multidetector got by this process

    International Nuclear Information System (INIS)

    Tirelli, M.; Lecolant, R.; Hecquet, R.

    1986-01-01

    The multidetector ionization chamber walls are fixed one related to the others and carried together with a tool above a resin bath to polymerize. After resin hardening, the detector includes resin basis. To contain the resin bath, the realization of a mould cut in a massive resin block are been provided for. This allows for its manutention all along the process without any deterioration risk [fr

  17. Measurement of time delay for a prospectively gated CT simulator.

    Science.gov (United States)

    Goharian, M; Khan, R F H

    2010-04-01

    For the management of mobile tumors, respiratory gating is the ideal option, both during imaging and during therapy. The major advantage of respiratory gating during imaging is that it is possible to create a single artifact-free CT data-set during a selected phase of the patient's breathing cycle. The purpose of the present work is to present a simple technique to measure the time delay during acquisition of a prospectively gated CT. The time delay of a Philips Brilliance BigBore (Philips Medical Systems, Madison, WI) scanner attached to a Varian Real-Time Position Management (RPM) system (Varian Medical Systems, Palo Alto, CA) was measured. Two methods were used to measure the CT time delay: using a motion phantom and using a recorded data file from the RPM system. In the first technique, a rotating wheel phantom was altered by placing two plastic balls on its axis and rim, respectively. For a desired gate, the relative positions of the balls were measured from the acquired CT data and converted into corresponding phases. Phase difference was calculated between the measured phases and the desired phases. Using period of motion, the phase difference was converted into time delay. The Varian RPM system provides an external breathing signal; it also records transistor-transistor logic (TTL) 'X-Ray ON' status signal from the CT scanner in a text file. The TTL 'X-Ray ON' indicates the start of CT image acquisition. Thus, knowledge of the start time of CT acquisition, combined with the real-time phase and amplitude data from the external respiratory signal, provides time-stamping of all images in an axial CT scan. The TTL signal with time-stamp was used to calculate when (during the breathing cycle) a slice was recorded. Using the two approaches, the time delay between the prospective gating signal and CT simulator has been determined to be 367 +/- 40 ms. The delay requires corrections both at image acquisition and while setting gates for the treatment delivery

  18. Breathing adapted radiotherapy for breast cancer: comparison of free breathing gating with the breath-hold technique

    DEFF Research Database (Denmark)

    Korreman, Stine Sofia; Pedersen, Anders N; Nøttrup, Trine Jakobi

    2005-01-01

    BACKGROUND AND PURPOSE: Adjuvant radiotherapy after breast-conserving surgery for breast cancer implies a risk of late cardiac and pulmonary toxicity. This is the first study to evaluate cardiopulmonary dose sparing of breathing adapted radiotherapy (BART) using free breathing gating......, and to compare this respiratory technique with voluntary breath-hold. PATIENTS AND METHODS: 17 patients were CT-scanned during non-coached breathing manoeuvre including free breathing (FB), end-inspiration gating (IG), end-expiration gating (EG), deep inspiration breath-hold (DIBH) and end-expiration breath......-hold (EBH). The Varian Real-time Position Management system (RPM) was used to monitor respiratory movement and to gate the scanner. For each breathing phase, a population based internal margin (IM) was estimated based on average chest wall excursion, and incorporated into an individually optimised three...

  19. Voltage-gated proton channel is expressed on phagosomes

    International Nuclear Information System (INIS)

    Okochi, Yoshifumi; Sasaki, Mari; Iwasaki, Hirohide; Okamura, Yasushi

    2009-01-01

    Voltage-gated proton channel has been suggested to help NADPH oxidase activity during respiratory burst of phagocytes through its activities of compensating charge imbalance and regulation of pH. In phagocytes, robust production of reactive oxygen species occurs in closed membrane compartments, which are called phagosomes. However, direct evidence for the presence of voltage-gated proton channels in phagosome has been lacking. In this study, the expression of voltage-gated proton channels was studied by Western blot with the antibody specific to the voltage-sensor domain protein, VSOP/Hv1, that has recently been identified as the molecular correlate for the voltage-gated proton channel. Phagosomal membranes of neutrophils contain VSOP/Hv1 in accordance with subunits of NADPH oxidases, gp91, p22, p47 and p67. Superoxide anion production upon PMA activation was significantly reduced in neutrophils from VSOP/Hv1 knockout mice. These are consistent with the idea that voltage-gated proton channels help NADPH oxidase in phagocytes to produce reactive oxygen species.

  20. Cardiac Computed Tomography (Multidetector CT, or MDCT)

    Science.gov (United States)

    ... Disease Venous Thromboembolism Aortic Aneurysm More Cardiac Computed Tomography (Multidetector CT, or MDCT) Updated:Sep 19,2016 What is Computerized Tomography (CT)? CT is a noninvasive test that uses ...

  1. Imaging of patent foramen ovale with 64-section multidetector CT.

    Science.gov (United States)

    Saremi, Farhood; Channual, Stephanie; Raney, Aidan; Gurudevan, Swaminatha V; Narula, Jagat; Fowler, Steven; Abolhoda, Amir; Milliken, Jeffrey C

    2008-11-01

    To investigate the feasibility of 64-section multidetector computed tomography (CT) by using CT angiography (a) to demonstrate anatomic detail of the interatrial septum pertinent to the patent foramen ovale (PFO), and (b) to visually detect left-to-right PFO shunts and compare these findings in patients who also underwent transesophageal echocardiography (TEE). In this institutional review board-approved HIPAA-compliant study, electrocardiographically gated coronary CT angiograms in 264 patients (159 men, 105 women; mean age, 60 years) were reviewed for PFO morphologic features. The length and diameter of the opening of the PFO tunnel, presence of atrial septal aneurysm (ASA), and PFO shunts were evaluated. A left-to-right shunt was assigned a grade according to length of contrast agent jet (grade 1, 1 cm to 2 cm; grade 3, >2 cm). In addition, 23 patients who underwent both modalities were compared (Student t test and linear regression analysis). A difference with P patent at the entry into the right atrium (PFO) in 62 patients (61.4% of patients with flap valve, 23.5% of total patients). A left-to-right shunt was detected in 44 (16.7% of total) patients (grade 1, 61.4%; grade 2, 34.1%; grade 3, 4.5%). No shunt was seen in patients without a flap valve. Mean length of PFO tunnel was 7.1 mm in 44 patients with a shunt and 12.1 mm in 57 patients with a flap valve without a shunt (P < .0001). In patients with a tunnel length of 6 mm or shorter, 92.6% of the shunts were seen. ASA was seen in 11 (4.2%) patients; of these patients, a shunt was seen in seven (63.6%). In 23 patients who underwent CT angiography and TEE, both modalities showed a PFO shunt in seven. Multidetector CT provides detailed anatomic information about size, morphologic features, and shunt grade of the PFO. Shorter tunnel length and septal aneurysms are frequently associated with left-to-right shunts in patients with PFO. (c) RSNA, 2008.

  2. Patent foramen ovale: detection with nongated multidetector CT.

    Science.gov (United States)

    Revel, Marie-Pierre; Faivre, Jean-Baptiste; Letourneau, Thierry; Henon, Hilde; Leys, Didier; Delannoy-Deken, Valérie; Remy-Jardin, Martine; Remy, Jacques

    2008-10-01

    To evaluate nongated multidetector computed tomography (CT) in the detection of patent foramen ovale (PFO) and atrial septal aneurysm (ASA) in comparison with transesophageal echocardiography (TEE). The study was approved by the institutional review board, and informed consent was obtained from all patients. One hundred five patients (57 men, 48 women; mean age, 53 years) with a recent stroke underwent TEE and multidetector CT on the same day. After injection of a diluted iodinated contrast material, a series of 2.4-mm-thick transverse images centered on the fossa ovalis were acquired in conjunction with release of the Valsalva maneuver. Two independent radiologists considered PFO present if left atrial enhancement was detected visually before enhancement of the pulmonary veins or if an early peak of left atrial enhancement was found at time-attenuation curve analysis. PFO was detected with 98% specificity (95% confidence interval [CI]: 0.91, 0.99). Overall sensitivity was 55% (95% CI: 0.38, 0.70), ranging from 28% for shunts classified as grade 1 at TEE to 91% for those classified as grade 4 at TEE. Interreader agreement was good (kappa = 0.81). Visual assessment was better than time-attenuation curve analysis, which enabled detection of only 15 of the 40 cases of PFO. Multidetector CT depicted only 22% of cases of ASA. The mean effective radiation dose was 2.3 mSv. Nongated multidetector CT can be used to diagnose high-grade shunts through a PFO, with 91% sensitivity and 98% specificity. Thus, PFO detection, in addition to routine CT evaluation of the lungs, could be indicated in patients with unexplained hypoxemia. (c) RSNA, 2008.

  3. Measurement of time delays in gated radiotherapy for realistic respiratory motions

    International Nuclear Information System (INIS)

    Chugh, Brige P.; Quirk, Sarah; Conroy, Leigh; Smith, Wendy L.

    2014-01-01

    Purpose: Gated radiotherapy is used to reduce internal motion margins, escalate target dose, and limit normal tissue dose; however, its temporal accuracy is limited. Beam-on and beam-off time delays can lead to treatment inefficiencies and/or geographic misses; therefore, AAPM Task Group 142 recommends verifying the temporal accuracy of gating systems. Many groups use sinusoidal phantom motion for this, under the tacit assumption that use of sinusoidal motion for determining time delays produces negligible error. The authors test this assumption by measuring gating time delays for several realistic motion shapes with increasing degrees of irregularity. Methods: Time delays were measured on a linear accelerator with a real-time position management system (Varian TrueBeam with RPM system version 1.7.5) for seven motion shapes: regular sinusoidal; regular realistic-shape; large (40%) and small (10%) variations in amplitude; large (40%) variations in period; small (10%) variations in both amplitude and period; and baseline drift (30%). Film streaks of radiation exposure were generated for each motion shape using a programmable motion phantom. Beam-on and beam-off time delays were determined from the difference between the expected and observed streak length. Results: For the system investigated, all sine, regular realistic-shape, and slightly irregular amplitude variation motions had beam-off and beam-on time delays within the AAPM recommended limit of less than 100 ms. In phase-based gating, even small variations in period resulted in some time delays greater than 100 ms. Considerable time delays over 1 s were observed with highly irregular motion. Conclusions: Sinusoidal motion shapes can be considered a reasonable approximation to the more complex and slightly irregular shapes of realistic motion. When using phase-based gating with predictive filters even small variations in period can result in time delays over 100 ms. Clinical use of these systems for patients

  4. Measurement of time delays in gated radiotherapy for realistic respiratory motions

    Energy Technology Data Exchange (ETDEWEB)

    Chugh, Brige P.; Quirk, Sarah; Conroy, Leigh; Smith, Wendy L., E-mail: Wendy.Smith@albertahealthservices.ca [Department of Medical Physics, Tom Baker Cancer Centre, Calgary, Alberta T2N 4N2 (Canada)

    2014-09-15

    Purpose: Gated radiotherapy is used to reduce internal motion margins, escalate target dose, and limit normal tissue dose; however, its temporal accuracy is limited. Beam-on and beam-off time delays can lead to treatment inefficiencies and/or geographic misses; therefore, AAPM Task Group 142 recommends verifying the temporal accuracy of gating systems. Many groups use sinusoidal phantom motion for this, under the tacit assumption that use of sinusoidal motion for determining time delays produces negligible error. The authors test this assumption by measuring gating time delays for several realistic motion shapes with increasing degrees of irregularity. Methods: Time delays were measured on a linear accelerator with a real-time position management system (Varian TrueBeam with RPM system version 1.7.5) for seven motion shapes: regular sinusoidal; regular realistic-shape; large (40%) and small (10%) variations in amplitude; large (40%) variations in period; small (10%) variations in both amplitude and period; and baseline drift (30%). Film streaks of radiation exposure were generated for each motion shape using a programmable motion phantom. Beam-on and beam-off time delays were determined from the difference between the expected and observed streak length. Results: For the system investigated, all sine, regular realistic-shape, and slightly irregular amplitude variation motions had beam-off and beam-on time delays within the AAPM recommended limit of less than 100 ms. In phase-based gating, even small variations in period resulted in some time delays greater than 100 ms. Considerable time delays over 1 s were observed with highly irregular motion. Conclusions: Sinusoidal motion shapes can be considered a reasonable approximation to the more complex and slightly irregular shapes of realistic motion. When using phase-based gating with predictive filters even small variations in period can result in time delays over 100 ms. Clinical use of these systems for patients

  5. Contribution to the development of the multidetector AMPHORA. Design of the electronic set up

    International Nuclear Information System (INIS)

    Stassi, P.

    1989-01-01

    The multidetector AMPHORA has been designed and built to be used to detect and identify all the particles produced in intermediate energy heavy ion reactions. This installation consist of 140 detectors built with CsI(TI) + NE102A and CsI(TI) + NE213 scintillators, covering nearly 81% of the solid angle around the target. These detectors can identify light charged particles, intermediate mass fragments and neutrons. The electronic set up associated is compact and requires little manual adjustment. It is built with special CAMAC modules which have the folowing functions: A 4 channel constant fraction discriminator and gate generator, a 16 channel charge to digital converter (12 bits), a 8 channel time to digital converter (12 bits), a 16 channel pile-up detector and a fast decision module. This thesis contains a detailed explanation of the principle and operation of the set up. It also contains a part which describes the way to connect all the modules of the electronic configuration for AMPHORA [fr

  6. Dual gated PET/CT imaging of small targets of the heart: method description and testing with a dynamic heart phantom.

    Science.gov (United States)

    Kokki, Tommi; Sipilä, Hannu T; Teräs, Mika; Noponen, Tommi; Durand-Schaefer, Nicolas; Klén, Riku; Knuuti, Juhani

    2010-01-01

    In PET imaging respiratory and cardiac contraction motions interfere the imaging of heart. The aim was to develop and evaluate dual gating method for improving the detection of small targets of the heart. The method utilizes two independent triggers which are sent periodically into list mode data based on respiratory and ECG cycles. An algorithm for generating dual gated segments from list mode data was developed. The test measurements showed that rotational and axial movements of point source can be separated spatially to different segments with well-defined borders. The effect of dual gating on detection of small moving targets was tested with a moving heart phantom. Dual gated images showed 51% elimination (3.6 mm out of 7.0 mm) of contraction motion of hot spot (diameter 3 mm) and 70% elimination (14 mm out of 20 mm) of respiratory motion. Averaged activity value of hot spot increases by 89% when comparing to non-gated images. Patient study of suspected cardiac sarcoidosis shows sharper spatial myocardial uptake profile and improved detection of small myocardial structures such as papillary muscles. The dual gating method improves detection of small moving targets in a phantom and it is feasible in clinical situations.

  7. Measurement of time delay for a prospectively gated CT simulator

    Directory of Open Access Journals (Sweden)

    Goharian M

    2010-01-01

    Full Text Available For the management of mobile tumors, respiratory gating is the ideal option, both during imaging and during therapy. The major advantage of respiratory gating during imaging is that it is possible to create a single artifact-free CT data-set during a selected phase of the patient′s breathing cycle. The purpose of the present work is to present a simple technique to measure the time delay during acquisition of a prospectively gated CT. The time delay of a Philips Brilliance BigBore™ (Philips Medical Systems, Madison, WI scanner attached to a Varian Real-Time Position Management™ (RPM system (Varian Medical Systems, Palo Alto, CA was measured. Two methods were used to measure the CT time delay: using a motion phantom and using a recorded data file from the RPM system. In the first technique, a rotating wheel phantom was altered by placing two plastic balls on its axis and rim, respectively. For a desired gate, the relative positions of the balls were measured from the acquired CT data and converted into corresponding phases. Phase difference was calculated between the measured phases and the desired phases. Using period of motion, the phase difference was converted into time delay. The Varian RPM system provides an external breathing signal; it also records transistor-transistor logic (TTL ′X-Ray ON′ status signal from the CT scanner in a text file. The TTL ′X-Ray ON′ indicates the start of CT image acquisition. Thus, knowledge of the start time of CT acquisition, combined with the real-time phase and amplitude data from the external respiratory signal, provides time-stamping of all images in an axial CT scan. The TTL signal with time-stamp was used to calculate when (during the breathing cycle a slice was recorded. Using the two approaches, the time delay between the prospective gating signal and CT simulator has been determined to be 367 ± 40 ms. The delay requires corrections both at image acquisition and while setting gates for

  8. Measurement of time delay for a prospectively gated CT simulator

    International Nuclear Information System (INIS)

    Goharian, M.; Khan, R.F.H.

    2010-01-01

    For the management of mobile tumors, respiratory gating is the ideal option, both during imaging and during therapy. The major advantage of respiratory gating during imaging is that it is possible to create a single artifact-free CT data-set during a selected phase of the patient's breathing cycle. The purpose of the present work is to present a simple technique to measure the time delay during acquisition of a prospectively gated CT. The time delay of a Philips Brilliance BigBore (Philips Medical Systems, Madison, WI) scanner attached to a Varian Real-Time Position Management (RPM) system (Varian Medical Systems, Palo Alto, CA) was measured. Two methods were used to measure the CT time delay: using a motion phantom and using a recorded data file from the RPM system. In the first technique, a rotating wheel phantom was altered by placing two plastic balls on its axis and rim, respectively. For a desired gate, the relative positions of the balls were measured from the acquired CT data and converted into corresponding phases. Phase difference was calculated between the measured phases and the desired phases. Using period of motion, the phase difference was converted into time delay. The Varian RPM system provides an external breathing signal; it also records transistor-transistor logic (TTL) 'X-Ray ON' status signal from the CT scanner in a text file. The TTL 'X-Ray ON' indicates the start of CT image acquisition. Thus, knowledge of the start time of CT acquisition, combined with the real-time phase and amplitude data from the external respiratory signal, provides time-stamping of all images in an axial CT scan. The TTL signal with time-stamp was used to calculate when (during the breathing cycle) a slice was recorded. Using the two approaches, the time delay between the prospective gating signal and CT simulator has been determined to be 367 ± 40 ms. The delay requires corrections both at image acquisition and while setting gates for the treatment delivery

  9. Multidetector CT portal venography in evaluation of portosystemic collateral vessels

    International Nuclear Information System (INIS)

    Agarwal, A.; Jain, M.

    2008-01-01

    This essay shows the usefulness of multidetector CT angiography for evaluation of the splenoportal venous system, which is essential in the management of patients with portal hypertension and its complications, such as portal vein thrombosis. By providing scanning with reconstruction of thin axial source images and reformatting into thicker multiplanar reformats, multidetector CT can help to determine the extent and location of portosystemic collateral vessels in patients with portal hypertension and is probably the optimal imaging technique in this setting.

  10. Double Chooz Improved Multi-Detector Measurements

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    The Double Chooz experiment (DC) is a reactor neutrino oscillation experiment running at Chooz nuclear power plant (2 reactors) in France. In 2011, DC first reported indication of non-zero θ13 with the far detector (FD) located at the maximum of oscillation effects (i.e. disappearance), thus challenging the CHOOZ non-observation limit. A robust observation of θ13 followed in 2012 by the Daya Bay experiments with multiple detector configurations. Since 2015 DC runs in a multi-detector configuration making thus the impact of several otherwise dominating systematics reduce strongly. DC’s unique almost "iso-flux" site, allows the near detector (ND) to become a direct accurate non-oscillation reference to the FD. Our first multi-detector results at MORIOND-2016 showed an intriguing deviation of θ13 with respect to the world average. We will address this issue in this seminar. The combined "reactor-θ13" measurement is expected to ...

  11. The effects of tumor motion on planning and delivery of respiratory-gated IMRT

    International Nuclear Information System (INIS)

    Hugo, Geoffrey D.; Agazaryan, Nzhde; Solberg, Timothy D.

    2003-01-01

    The purpose of this study is to investigate the effects of object motion on the planning and delivery of IMRT. Two phantoms containing objects were imaged using CT under a variety of motion conditions. The effects of object motion on axial CT acquisition with and without gating were assessed qualitatively and quantitatively. Measurements of effective slice width and position for the CT scans were made. Mutual information image fusion was adapted for use as a quantitative measure of object deformation in CT images. IMRT plans were generated on the CT scans of the moving and gated object images. These plans were delivered with motion, with and without gating, and the delivery error between the moving deliveries and a nonmoving delivery was assessed using a scalable vector-based index. Motion during CT acquisition produces motion artifact, object deformation, and object mispositioning, which can be substantially reduced with gating. Objects that vary in cross section in the direction of motion exhibit the most deformation in CT images. Mutual information provides a useful quantitative estimate of object deformation. The delivery of IMRT in the presence of target motion significantly alters the delivered dose distribution in relation to the planned distribution. The utilization of gating for IMRT treatment, including imaging, planning, and delivery, significantly reduces the errors introduced by object motion

  12. Multi-detector CT (MDCT in bowel and mesenteric injury

    Directory of Open Access Journals (Sweden)

    Vajjalla Ravikumar

    2013-04-01

    Full Text Available Objectives: To evaluate multi-detector CT (MDCT findings in bowel and mesenteric injury due to blunt abdominal trauma.Method: Retrospective evaluation of MDCT scan reports of patients admitted in Hamad Medical Corporation, Doha, Qatar with bowel and mesenteric injury during the period of January 2005 to April 2008.Results: MDCT, without using oral contrast, clearly demonstrated various specific and less specific findings of bowel and mesenteric injury.Conclusion: Multi-detector CT is an excellent diagnostic modality in bowel and mesenteric injury. Routine administration of oral contrast agent is not mandatory for initial evaluation of these patients.

  13. Multi-detector row computed tomography angiography of peripheral arterial disease

    International Nuclear Information System (INIS)

    Kock, Marc C.J.M.; Dijkshoorn, Marcel L.; Pattynama, Peter M.T.; Myriam Hunink, M.G.

    2007-01-01

    With the introduction of multi-detector row computed tomography (MDCT), scan speed and image quality has improved considerably. Since the longitudinal coverage is no longer a limitation, multi-detector row computed tomography angiography (MDCTA) is increasingly used to depict the peripheral arterial runoff. Hence, it is important to know the advantages and limitations of this new non-invasive alternative for the reference test, digital subtraction angiography. Optimization of the acquisition parameters and the contrast delivery is important to achieve a reliable enhancement of the entire arterial runoff in patients with peripheral arterial disease (PAD) using fast CT scanners. The purpose of this review is to discuss the different scanning and injection protocols using 4-, 16-, and 64-detector row CT scanners, to propose effective methods to evaluate and to present large data sets, to discuss its clinical value and major limitations, and to review the literature on the validity, reliability, and cost-effectiveness of multi-detector row CT in the evaluation of PAD. (orig.)

  14. Three-Dimensional Respiratory-Gated Coronary Mr Angiography with Reference to X-Ray Coronary Angiography

    International Nuclear Information System (INIS)

    Ikonen, A. E. J.; Manninen, H. I.; Vainio, P.; Vanninen, R. L.; Matsi, P. J.; Soimakallio, S.; Hirvonen, T.P.J.; Hartikainen, J.E.K.

    2003-01-01

    Purpose: To assess the clinical value of three-dimensional coronary MR angiography (CMRA) in the detection of significant coronary artery stenosis using conventional X-ray angiography as the standard reference. Material and Methods: Sixty-nine patients underwent X-ray coronary angiography and CMRA because of suspected or previously diagnosed coronary artery disease. MRI was performed with a 1.5-T whole body imaging system using ECG-triggered 3D gradient echo sequence with retrospective navigator echo respiratory gating and fat suppression. Results: A total of 276 coronary artery segments were analyzed. The X-ray coronary angiography was normal in 22 patients. Significant proximal stenoses (exceeding 50%) or occlusions were present in 102 coronary artery segments. In all, 120 stenoses or occlusions were identified in CMRA. Sixteen percent of the coronary artery segments had to be excluded because of poor image quality. The overall sensitivity and specificity for MRA for identification of significant stenosis were 75% and 62%, respectively. CMRA correctly detected 89% of patients with at least one vessel disease, but 6 patients with coronary artery disease would have been missed. Conclusions: Because of the high data exclusion and false-negative case rate, CMRA with retrospective navigator echo triggering is at present not suitable as a clinical screening method in coronary artery disease

  15. Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates

    International Nuclear Information System (INIS)

    Berbeco, Ross I.; Nishioka, Seiko; Shirato, Hiroki; Jiang, Steve B.

    2006-01-01

    It has been noted that some lung tumors exhibit large periodic motion due to respiration. To limit the amount of dose to healthy lung tissues, many clinics have begun gating radiotherapy treatment using externally placed surrogates. It has been observed by several institutions that the end-of-exhale (EOE) tumor position is more reproducible than other phases of the breathing cycle, so the gating window is often set there. From a treatment planning perspective, end-of-inhale (EOI) phase might be preferred for gating because the expanded lungs will further decrease the healthy tissue within the treatment field. We simulate gated treatment at the EOI phase, using a set of recently measured internal/external anatomy patient data. This paper attempts to answer three questions: (1) How much is the tumor residual motion when we use an external surrogate gating window at EOI? (2) How could we reduce the residual motion in the EOI gating window? (3) Is there a preference for amplitude- versus phase-based gating at EOI? We found that under free breathing conditions the residual motion of the tumors is much larger for EOI phase than for EOE phase. The mean values of residual motion at EOI were found to be 2.2 and 2.7 mm for amplitude- and phase-based gating, respectively, and, at EOE, 1.0 and 1.2 mm for amplitude- and phase-based gating, respectively. However, we note that the residual motion in the EOI gating window is correlated well with the reproducibility of the external surface position in the EOI phase. Using the results of a published breath-coaching study, we deduce that the residual motion of a lung tumor at EOI would approach that at EOE, with the same duty cycle (30%), under breath-coaching conditions. Additionally, we found that under these same conditions, phase-based gating approaches the same residual motion as amplitude-based gating, going from a 28% difference to 11%, for the patient with the largest difference between the two gating modalities. We conclude

  16. Improving the Spatial Alignment in PET/CT Using Amplitude-Based Respiration-Gated PET and Respiration-Triggered CT

    NARCIS (Netherlands)

    Vos, C.S. van der; Grootjans, W.; Osborne, D.R.; Meeuwis, A.P.; Hamill, J.J.; Acuff, S.; Geus-Oei, L.F. de; Visser, E.P.

    2015-01-01

    Respiratory motion during PET can cause inaccuracies in the quantification of radiotracer uptake, which negatively affects PET-guided radiotherapy planning. Quantitative accuracy can be improved by respiratory gating. However, additional miscalculation of standardized uptake value (SUV) in PET

  17. TU-D-202-03: Gating Is the Best ITV Killer

    International Nuclear Information System (INIS)

    Low, D.

    2016-01-01

    Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion-inclusive approach with better imaging and smaller margins, called mid-position CT. 2) The tracking approach and 3) The gating approach. The following topics will be addressed by Marcel van Herk (“Is ITV the correct motion encompassing strategy”): Magnitude of respiratory motion, effect of motion on radiotherapy, motion encompassing strategies, and software solutions to assist in motion encompassing strategies. Then Paul Keall (“Make margins simple: Use real-time target tracking”) will discuss tracking with: clinical drivers for tracking, current clinical status of tumor tracking, future tumor tracking technology, and margin margin challenges with and without tracking. Finally Daniel Low will discuss gating (“Gating is the best ITV killer”): why ITV in the first place, requirements for planning, requirements at the machine, benefits and costs. The session will end with a discussion and live demo of motion simulation software to illustrate the issues and explain the relative benefit and appropriate uses for the three methods. Learning Objectives: Explain the 4D imaging and treatment planning process. Summarize the various approaches to deal with respiratory motion during radiotherapy Discuss the tradeoffs involved when choosing one of the three discussed approaches. Explain in which situation each method is the best choice Research is partly funded by Elekta Oncology Systems and the Dutch Cancer

  18. TU-D-202-03: Gating Is the Best ITV Killer

    Energy Technology Data Exchange (ETDEWEB)

    Low, D.

    2016-06-15

    Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion-inclusive approach with better imaging and smaller margins, called mid-position CT. 2) The tracking approach and 3) The gating approach. The following topics will be addressed by Marcel van Herk (“Is ITV the correct motion encompassing strategy”): Magnitude of respiratory motion, effect of motion on radiotherapy, motion encompassing strategies, and software solutions to assist in motion encompassing strategies. Then Paul Keall (“Make margins simple: Use real-time target tracking”) will discuss tracking with: clinical drivers for tracking, current clinical status of tumor tracking, future tumor tracking technology, and margin margin challenges with and without tracking. Finally Daniel Low will discuss gating (“Gating is the best ITV killer”): why ITV in the first place, requirements for planning, requirements at the machine, benefits and costs. The session will end with a discussion and live demo of motion simulation software to illustrate the issues and explain the relative benefit and appropriate uses for the three methods. Learning Objectives: Explain the 4D imaging and treatment planning process. Summarize the various approaches to deal with respiratory motion during radiotherapy Discuss the tradeoffs involved when choosing one of the three discussed approaches. Explain in which situation each method is the best choice Research is partly funded by Elekta Oncology Systems and the Dutch Cancer

  19. Impact of multi-detector row computed tomography on the tactics of cardiovascular surgery. From qualitative evaluation to quantitative assessment

    International Nuclear Information System (INIS)

    Imagawa, Hiroshi; Kawachi, Kanji; Takano, Shinji

    2005-01-01

    We assessed the role of multi-detector row computed tomography in cardiovascular surgery. The efficacy of multi-detector row computed tomography was assessed concerning the graft patency of coronary artery bypass, arterial atheromatous degeneration, small vessel imaging, and left ventricular volume measurement. Images were reconstructed using both the volume-rendering and the maximum-intensity-profile methods. Arterial atherosclerotic degeneration was assessed by aortic wall volume and aortic calcification volume. In the assessment of bypass graft patency, multidetector row computed tomography showed a 98% correct positive ratio with sensitivity and specificity of 98% and 100%, respectively. Atheromatous degeneration showed matching results in more than 70% of cases compared with intraoperative findings. More than 92% of arterial branches with diameters of 3 mm or greater were detected by preoperative multi-detector row computed tomography images, though only 6% of branches with diameters of 2 mm or less could be visualized. There was a positive linear correlation between left ventricular volumes determined by multi-detector row computed tomography and those calculated from cine angiography. Multi-detector row computed tomography clearly visualized coronary bypass grafts and aortic arterial branches, providing detailed vascular images. Atheromatous degeneration assessed by multi-detector row computed tomography was equivalent with intraoperative findings in more than 70% of cases. Left ventricular volumes measured by multi-detector row computed tomography correlated closely with those determined by cine-angiography. Multidetector row computed tomography is an efficient and promising modality in cardiovascular surgery. (author)

  20. The detectability of the origin of the inferior phrenic artery by paging method on multidetector-row CT angiography

    International Nuclear Information System (INIS)

    Terayama, Koshi

    2005-01-01

    We evaluated the ability to detect the origin of the inferior phrenic artery (IPA) by paging method on multidetector-row computed tomography (CT) angiography. In 104 patients who underwent multidetector-row CT, detectability of the origin of the IPA was assessed. In addition, in 30 patients in whom arteriographic study was performed, the IPA findings on multidetector-row CT were compared with those on arteriography. In 100 patients (96%) the origin of the right IPA was demonstrated with multidetector-row CT and in 93 patients (89%) the origin of the left IPA was demonstrated. CT angiographic findings concurred with arteriographic findings in all 30 patients (100%) who underwent arteriographic study. In conclusion, paging method on multidetector-row CT angiography provides valuable anatomical information regarding IPA. (author)

  1. Diffusion-weighted MR-imaging for the detection of pulmonary nodules at 1.5 Tesla: intraindividual comparison with multidetector computed tomography

    International Nuclear Information System (INIS)

    Regier, Marc; Schwarz, Dorothee; Henes, Frank Oliver; Groth, Michael; Begemann, Philipp G.C.; Adam, Gerhard; Kooijman, Hendrik

    2011-01-01

    To investigate the feasibility of diffusion-weighted imaging (DWI) MRI for detecting pulmonary nodules at 1.5 Tesla in comparison with standard multidetector computed tomography (MDCT). Twenty patients with disseminated cancer disease in which MDCT had assured the presence of at least one pulmonary nodule were examined using a respiratory-gated DWI MR-sequence. Grey scale inverted source images and coronal maximum intensity projection (MIP) images were consensually analysed by two experienced radiologists. Size and location of any nodule detected were assessed. Additionally, the readers evaluated each hemithorax for the presence of at least one nodule and applied a four-point conspicuity scale (1-hemithorax definitely affected; 4-hemithorax definitely not affected). MDCT data served as reference. At MDCT, a total of 71 pulmonary noduIes was found (size 3–5 mm, n = 16; 6–9 mm, n = 22; ≥10 mm, n = 33). For the DWI MR-sequence, a sensitivity of 86.4% was calculated for nodules ranging 6–9 mm and 97% for nodules ≥10 mm. In contrast, only 43.8% of lesions ≤5 mm was detected. The separate analysis of each hemithorax for the presence of at least one pulmonary nodule revealed a specificity rate, PPV and NPV of DWI-MR of 92.3%, 96% and 80%, respectively. The presented study is the first to confirm the diagnostic potential of DWI-MR in the detection of solid lung nodules. This technique allows for the detection of nodules ≥6 mm with reasonably high sensitivity rates (>86%). The observation of false positive findings decreases the accuracy of this approach compared with MDCT.

  2. Image-guided adaptive gating of lung cancer radiotherapy: a computer simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Aristophanous, Michalis; Rottmann, Joerg; Park, Sang-June; Berbeco, Ross I [Department of Radiation Oncology, Brigham and Women' s Hospital, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA (United States); Nishioka, Seiko [Department of Radiology, NTT Hospital, Sapporo (Japan); Shirato, Hiroki, E-mail: maristophanous@lroc.harvard.ed [Department of Radiation Medicine, Hokkaido University School of Medicine, Sapporo (Japan)

    2010-08-07

    The purpose of this study is to investigate the effect that image-guided adaptation of the gating window during treatment could have on the residual tumor motion, by simulating different gated radiotherapy techniques. There are three separate components of this simulation: (1) the 'Hokkaido Data', which are previously measured 3D data of lung tumor motion tracks and the corresponding 1D respiratory signals obtained during the entire ungated radiotherapy treatments of eight patients, (2) the respiratory gating protocol at our institution and the imaging performed under that protocol and (3) the actual simulation in which the Hokkaido Data are used to select tumor position information that could have been collected based on the imaging performed under our gating protocol. We simulated treatments with a fixed gating window and a gating window that is updated during treatment. The patient data were divided into different fractions, each with continuous acquisitions longer than 2 min. In accordance to the imaging performed under our gating protocol, we assume that we have tumor position information for the first 15 s of treatment, obtained from kV fluoroscopy, and for the rest of the fractions the tumor position is only available during the beam-on time from MV imaging. The gating window was set according to the information obtained from the first 15 s such that the residual motion was less than 3 mm. For the fixed gating window technique the gate remained the same for the entire treatment, while for the adaptive technique the range of the tumor motion during beam-on time was measured and used to adapt the gating window to keep the residual motion below 3 mm. The algorithm used to adapt the gating window is described. The residual tumor motion inside the gating window was reduced on average by 24% for the patients with regular breathing patterns and the difference was statistically significant (p-value = 0.01). The magnitude of the residual tumor motion

  3. Set-up of light nuclei multidetector

    International Nuclear Information System (INIS)

    Drouet, A.

    1985-01-01

    In order to study mechanisms of reactions produced by heavy ions in the GANIL energy range (15-100 MeV/A), a multidetector capable to detect large multiplicities for particles and light nuclei is necessary. The multidetector set up covers the 3-30 0 angular range and consists of 96 counters (NE102 plastic scintillator sheet, 2mm thick). The apparatus must identify the nuclear charge of the detected particles. Using the apparatus at GANIL leaded to carry out data processing tools in conversationnal mode and to write on experimental area programs performing and monitoring data acquisition. A test carried out with a 44 MeV/A argon beam showed that the apparatus was working properly: the identification in nuclear charge between Z=1 (proton) and Z=7 (nitrogen) is good. Results of the test allow to draw light production curves in the NE102 plastic scintillator for the following ions: 1 H, 4 He, 7 Li, 9 Be, 11 B, 12 C, 14 N, in the 13 to 44 MeV/A energy range [fr

  4. Evaluation of dose according to the volume and respiratory range during SBRT in lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Deuk Hee [Dept. of Radiation Oncology, Busan Paik Hospital, Inje University, Busan (Korea, Republic of); Park, Eun Tae; Kim, Jung Hoon; Kang, Se Seik [Dept. of Radiological Science, College of Health Sciences, Catholic University of Pusan, Busan (Korea, Republic of)

    2016-09-15

    Stereotactic body radiotherapy is effective technic in radiotherapy for low stage lung cancer. But lung cancer is affected by respiratory so accurately concentrate high dose to the target is very difficult. In this study, evaluated the target volume according to how to take the image. And evaluated the dose by photoluminescence glass dosimeter according to how to contour the volume and respiratory range. As a result, evaluated the 4D CT volume was 10.4 cm{sup 3} which was closest value of real size target. And in dose case is internal target volume dose was 10.82, 16.88, 21.90 Gy when prescribed dose was 10, 15, 20 Gy and it was the highest dose. Respiratory gated radiotherapy dose was more higher than internal target volume. But it made little difference by respiratory range. Therefore, when moving cancer treatment, acquiring image by 4D CT, contouring internal target volume and respiratory gated radiotherapy technic would be the best way.

  5. Evaluation of dose according to the volume and respiratory range during SBRT in lung cancer

    International Nuclear Information System (INIS)

    Lee, Deuk Hee; Park, Eun Tae; Kim, Jung Hoon; Kang, Se Seik

    2016-01-01

    Stereotactic body radiotherapy is effective technic in radiotherapy for low stage lung cancer. But lung cancer is affected by respiratory so accurately concentrate high dose to the target is very difficult. In this study, evaluated the target volume according to how to take the image. And evaluated the dose by photoluminescence glass dosimeter according to how to contour the volume and respiratory range. As a result, evaluated the 4D CT volume was 10.4 cm 3 which was closest value of real size target. And in dose case is internal target volume dose was 10.82, 16.88, 21.90 Gy when prescribed dose was 10, 15, 20 Gy and it was the highest dose. Respiratory gated radiotherapy dose was more higher than internal target volume. But it made little difference by respiratory range. Therefore, when moving cancer treatment, acquiring image by 4D CT, contouring internal target volume and respiratory gated radiotherapy technic would be the best way

  6. Effects of acute respiratory virus infection upon tracheal mucous transport

    International Nuclear Information System (INIS)

    Gerrard, C.S.; Levandowski, R.A.; Gerrity, T.R.; Yeates, D.B.; Klein, E.

    1985-01-01

    Tracheal mucous velocity was measured in 13 healthy non-smokers using an aerosol labelled with /sup 99m/Tc and a multidetector probe during respiratory virus infections. The movement of boluses of tracheal mucous were either absent or reduced in number in five subjects with myxovirus infection (four influenza and one respiratory syncytial virus) within 48 hr of the onset of symptoms and in four subjects 1 wk later. One subject with influenza still had reduced bolus formation 12-16 wk after infection. Frequent coughing was a feature of those subjects with absent tracheal boluses. In contrast, four subjects with rhinovirus infection had normal tracheal mucous velocity at 48 hr after the onset of symptoms (4.1 +/- 1.3 mm/min). Tracheal mucous velocity was also normal (4.6 +/- 1.1 mm/min) in four subjects in whom no specific viral agent could be defined but had typical symptomatology of respiratory viral infection. During health tracheal mucous velocity was normal (4.8 +/- 1.6 mm/min) in the eleven subjects who had measurements made. Disturbances in tracheal mucous transport during virus infection appear to depend upon the type of virus and are most severe in influenza A and respiratory syncytial virus infection

  7. Clinical usefulness of multidetector-row CT to evaluate coronary artery calcium score in type 2 diabetes

    International Nuclear Information System (INIS)

    Nishioka, Makiko; Sakuma, Toru; Sano, Hironari; Utsunomiya, Kazunori; Agata, Toshihiko; Shimizu, Keisuke; Tajima, Naoko

    2004-01-01

    According to recent studies, multidetector-row CT (MDCT) with a retrospective electrocardiogram (ECG)-gating reconstruction algorithm shows a high correlation with coronary artery calcium score determined using electron-beam CT. Diabetes leads to many macrovascular complications, including coronary artery disease. The aim of this study was to evaluate risk factors for cardiac macroangiopathy in type 2 diabetes using MDCT. An observational cross-sectional study was performed in 90 patients with diabetes mellitus. Coronary calcium data was acquired by MDCT (SOMATOM Volume Zoom, Siemens AG, Medical Solutions, Germany). Physical examinations, laboratory data, glycemic control, and control of other risk factors were analyzed. The coronary artery calcium score increased with age. Multivariant analysis revealed that the coronary calcium score was closely correlated with electrocardiogram evaluation and control of hypertension. Coronary artery calcium score as determined by MDCT can be used as a screening radiological examination for cardiac macroangiopathy in diabetes patients with electrocardiogram abnormality and hypertension. (author)

  8. Non rigid respiratory motion correction in whole body PET/MR imaging

    International Nuclear Information System (INIS)

    Fayad, Hadi; Schmidt, Holger; Wuerslin, Christian; Visvikis, Dimitris

    2014-01-01

    Respiratory motion in PET/MR imaging leads to reduced quantitative and qualitative image accuracy. Correction methodologies include the use of respiratory synchronized gated frames which lead to low signal to noise ratio (SNR) given that each frame contains only part of the count available throughout an average PET acquisition. In this work, 4D MRI extracted elastic transformations were applied to list-mode data either inside the image reconstruction or to the reconstructed respiratory synchronized images to obtain respiration corrected PET images.

  9. MARS - a multidetector array for reaction studies

    International Nuclear Information System (INIS)

    Ball, G.C.; Davies, W.G.; Forster, J.S.

    1988-03-01

    The proposal for MARS, a Multidetector Array for Reaction Studies is presented. MARS consists of a large, high-vacuum vessel enclosing an array of 128 scintillation detectors for use in studies of heavy-ion collisions at TASCC. The instrument will be funded and owned jointly by AECL and NSERC

  10. Video-coaching as biofeedback tool to improve gated treatments. Possibilities and limitations

    International Nuclear Information System (INIS)

    Cossmann, Peter H.

    2012-01-01

    For respiratory gated radiotherapy the manufacturers of linear accelerators offer dedicated gating technologies. The video-based Varian RPM Gating system (Varian Medical Systems, Palo Alto/CA, USA) includes in a standard configuration a support tool for regular breathing called audiocoaching. As this approach has limitations regarding direct control of the patient's breathing due to a missing feedback, we designed an additional tool offering videocoaching. In order to evaluate the impact of this additional functionality, we measured parameters defining the image quality of 4D-CT data as well as the treatment duration which is mainly influenced by the patient's limited ability to achieve a stable breathing pattern. (orig.)

  11. Visual and Quantitative Analysis Methods of Respiratory Patterns for Respiratory Gated PET/CT.

    Science.gov (United States)

    Son, Hye Joo; Jeong, Young Jin; Yoon, Hyun Jin; Park, Jong-Hwan; Kang, Do-Young

    2016-01-01

    We integrated visual and quantitative methods for analyzing the stability of respiration using four methods: phase space diagrams, Fourier spectra, Poincaré maps, and Lyapunov exponents. Respiratory patterns of 139 patients were grouped based on the combination of the regularity of amplitude, period, and baseline positions. Visual grading was done by inspecting the shape of diagram and classified into two states: regular and irregular. Quantitation was done by measuring standard deviation of x and v coordinates of Poincaré map (SD x , SD v ) or the height of the fundamental peak ( A 1 ) in Fourier spectrum or calculating the difference between maximal upward and downward drift. Each group showed characteristic pattern on visual analysis. There was difference of quantitative parameters (SD x , SD v , A 1 , and MUD-MDD) among four groups (one way ANOVA, p = 0.0001 for MUD-MDD, SD x , and SD v , p = 0.0002 for A 1 ). In ROC analysis, the cutoff values were 0.11 for SD x (AUC: 0.982, p quantitative indices of respiratory stability and determining quantitative cutoff value for differentiating regular and irregular respiration.

  12. Multidetector computed tomography in the preoperative staging of gastric adenocarcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Ricardo Hoelz de Oliveira; Penachim, Thiago Jose; Martins, Daniel Lahan; Andreollo, Nelson Adami; Caserta, Nelson Marcio Gomes, E-mail: rhobarros@hotmail.com [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil)

    2015-03-15

    Objective: To evaluate the role of multidetector computed tomography in the preoperative investigation of tumor invasion depth and lymph node and metastatic involvement according to the TNM classification, in patients with gastric adenocarcinoma. Materials and Methods: Fifty-four patients with biopsy-confirmed gastric cancer underwent preoperative staging with 64-channel multidetector computed tomography. Two independent radiologists analyzed the images and classified the findings. Sensitivity, specificity, accuracy and overall accuracy were calculated for each observer. The interobserver agreement was also evaluated. Results: The accuracy in the classification of categories T ranged from 74% to 96% for observer 1 and from 80% to 92% for observer 2. The overall accuracy was 70% for both observers. The weighted kappa index was 0.75, consistent with a significant interobserver agreement. The accuracy in the classification of lymph node involvement (category N) ranged from 55% to 79% for observer 1 and from 73% to 82% for observer 2. The evaluation of metastatic involvement showed an overall accuracy of 89.6% for both observers. Conclusion: 64-channel multidetector computed tomography demonstrated clinically relevant accuracy in the preoperative staging of gastric adenocarcinoma as regards invasion depth (T category) and metastatic involvement (M category). (author)

  13. Multidetector computed tomography in the preoperative staging of gastric adenocarcinoma

    International Nuclear Information System (INIS)

    Barros, Ricardo Hoelz de Oliveira; Penachim, Thiago Jose; Martins, Daniel Lahan; Andreollo, Nelson Adami; Caserta, Nelson Marcio Gomes

    2015-01-01

    Objective: To evaluate the role of multidetector computed tomography in the preoperative investigation of tumor invasion depth and lymph node and metastatic involvement according to the TNM classification, in patients with gastric adenocarcinoma. Materials and Methods: Fifty-four patients with biopsy-confirmed gastric cancer underwent preoperative staging with 64-channel multidetector computed tomography. Two independent radiologists analyzed the images and classified the findings. Sensitivity, specificity, accuracy and overall accuracy were calculated for each observer. The interobserver agreement was also evaluated. Results: The accuracy in the classification of categories T ranged from 74% to 96% for observer 1 and from 80% to 92% for observer 2. The overall accuracy was 70% for both observers. The weighted kappa index was 0.75, consistent with a significant interobserver agreement. The accuracy in the classification of lymph node involvement (category N) ranged from 55% to 79% for observer 1 and from 73% to 82% for observer 2. The evaluation of metastatic involvement showed an overall accuracy of 89.6% for both observers. Conclusion: 64-channel multidetector computed tomography demonstrated clinically relevant accuracy in the preoperative staging of gastric adenocarcinoma as regards invasion depth (T category) and metastatic involvement (M category). (author)

  14. Automated patient setup and gating using cone beam computed tomography projections

    DEFF Research Database (Denmark)

    Wan, Hanlin; Bertholet, Jenny; Ge, Jiajia

    2016-01-01

    In radiation therapy, fiducial markers are often implanted near tumors and used for patient positioning and respiratory gating purposes. These markers are then used to manually align the patients by matching the markers in the cone beam computed tomography (CBCT) reconstruction to those...

  15. Low-dose cardio-respiratory phase-correlated cone-beam micro-CT of small animals.

    Science.gov (United States)

    Sawall, Stefan; Bergner, Frank; Lapp, Robert; Mronz, Markus; Karolczak, Marek; Hess, Andreas; Kachelriess, Marc

    2011-03-01

    Micro-CT imaging of animal hearts typically requires a double gating procedure because scans during a breath-hold are not possible due to the long scan times and the high respiratory rates, Simultaneous respiratory and cardiac gating can either be done prospectively or retrospectively. True five-dimensional information can be either retrieved with retrospective gating or with prospective gating if several prospective gates are acquired. In any case, the amount of information available to reconstruct one volume for a given respiratory and cardiac phase is orders of magnitud lower than the total amount of information acquired. For example, the reconstruction of a volume from a 10% wide respiratory and a 20% wide cardiac window uses only 2% of the data acquired. Achieving a similar image quality as a nongated scan would therefore require to increase the amount of data and thereby the dose to the animal by up to a factor of 50. To achieve the goal of low-dose phase-correlated (LDPC) imaging, the authors propose to use a highly efficient combination of slightly modified existing algorithms. In particular, the authors developed a variant of the McKinnon-Bates image reconstruction algorithm and combined it with bilateral filtering in up to five dimensions to significantly reduce image noise without impairing spatial or temporal resolution. The preliminary results indicate that the proposed LDPC reconstruction method typically reduces image noise by a factor of up to 6 (e.g., from 170 to 30 HU), while the dose values lie in a range from 60 to 500 mGy. Compared to other publications that apply 250-1800 mGy for the same task [C. T. Badea et al., "4D micro-CT of the mouse heart," Mol. Imaging 4(2), 110-116 (2005); M. Drangova et al., "Fast retrospectively gated quantitative four-dimensional (4D) cardiac micro computed tomography imaging of free-breathing mice," Invest. Radiol. 42(2), 85-94 (2007); S. H. Bartling et al., "Retrospective motion gating in small animal CT of mice

  16. CASE SERIES Multi-detector computer tomography venography ...

    African Journals Online (AJOL)

    in the curved coronal plane with particular reference to the course of the common and external iliac veins through the pelvis. Axial venous. Aim. To evaluate the role of multi-detector computer tomography venography (MDCTV), compared with conventional venography, as a diagnostic tool in the management of patients with ...

  17. Characterizing string-of-pearls colloidal silica by multidetector hydrodynamic chromatography and comparison to multidetector size-exclusion chromatography, off-line multiangle static light scattering, and transmission electron microscopy.

    Science.gov (United States)

    Brewer, Amandaa K; Striegel, André M

    2011-04-15

    The string-of-pearls-type morphology is ubiquitous, manifesting itself variously in proteins, vesicles, bacteria, synthetic polymers, and biopolymers. Characterizing the size and shape of analytes with such morphology, however, presents a challenge, due chiefly to the ease with which the "strings" can be broken during chromatographic analysis or to the paucity of information obtained from the benchmark microscopy and off-line light scattering methods. Here, we address this challenge with multidetector hydrodynamic chromatography (HDC), which has the ability to determine, simultaneously, the size, shape, and compactness and their distributions of string-of-pearls samples. We present the quadruple-detector HDC analysis of colloidal string-of-pearls silica, employing static multiangle and quasielastic light scattering, differential viscometry, and differential refractometry as detection methods. The multidetector approach shows a sample that is broadly polydisperse in both molar mass and size, with strings ranging from two to five particles, but which also contains a high concentration of single, unattached "pearls". Synergistic combination of the various size parameters obtained from the multiplicity of detectors employed shows that the strings with higher degrees of polymerization have a shape similar to the theory-predicted shape of a Gaussian random coil chain of nonoverlapping beads, while the strings with lower degrees of polymerization have a prolate ellipsoidal shape. The HDC technique is contrasted experimentally with multidetector size-exclusion chromatography, where, even under extremely gentle conditions, the strings still degraded during analysis. Such degradation is shown to be absent in HDC, as evidenced by the fact that the molar mass and radius of gyration obtained by HDC with multiangle static light scattering detection (HDC/MALS) compare quite favorably to those determined by off-line MALS analysis under otherwise identical conditions. The

  18. Accuracy Improvement of Boron Meter Adopting New Fitting Function and Multi-Detector

    Directory of Open Access Journals (Sweden)

    Chidong Kong

    2016-12-01

    Full Text Available This paper introduces a boron meter with improved accuracy compared with other commercially available boron meters. Its design includes a new fitting function and a multi-detector. In pressurized water reactors (PWRs in Korea, many boron meters have been used to continuously monitor boron concentration in reactor coolant. However, it is difficult to use the boron meters in practice because the measurement uncertainty is high. For this reason, there has been a strong demand for improvement in their accuracy. In this work, a boron meter evaluation model was developed, and two approaches were considered to improve the boron meter accuracy: the first approach uses a new fitting function and the second approach uses a multi-detector. With the new fitting function, the boron concentration error was decreased from 3.30 ppm to 0.73 ppm. With the multi-detector, the count signals were contaminated with noise such as field measurement data, and analyses were repeated 1,000 times to obtain average and standard deviations of the boron concentration errors. Finally, using the new fitting formulation and multi-detector together, the average error was decreased from 5.95 ppm to 1.83 ppm and its standard deviation was decreased from 0.64 ppm to 0.26 ppm. This result represents a great improvement of the boron meter accuracy.

  19. Accuracy improvement of boron meter adopting new fitting function and multi-detector

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Chidong; Lee, Hyun Suk; Tak, Tae Woo; Lee, Deok Jung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); KIm, Si Hwan; Lyou, Seok Jean [Users Incorporated Company, Hansin S-MECA, Daejeon (Korea, Republic of)

    2016-12-15

    This paper introduces a boron meter with improved accuracy compared with other commercially available boron meters. Its design includes a new fitting function and a multi-detector. In pressurized water reactors (PWRs) in Korea, many boron meters have been used to continuously monitor boron concentration in reactor coolant. However, it is difficult to use the boron meters in practice because the measurement uncertainty is high. For this reason, there has been a strong demand for improvement in their accuracy. In this work, a boron meter evaluation model was developed, and two approaches were considered to improve the boron meter accuracy: the first approach uses a new fitting function and the second approach uses a multi-detector. With the new fitting function, the boron concentration error was decreased from 3.30 ppm to 0.73 ppm. With the multi-detector, the count signals were contaminated with noise such as field measurement data, and analyses were repeated 1,000 times to obtain average and standard deviations of the boron concentration errors. Finally, using the new fitting formulation and multi-detector together, the average error was decreased from 5.95 ppm to 1.83 ppm and its standard deviation was decreased from 0.64 ppm to 0.26 ppm. This result represents a great improvement of the boron meter accuracy.

  20. Respiratory gated PET/CT in a European multicentre retrospective study: added diagnostic value in detection and characterization of lung lesions

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, Luca; Elisei, Federica [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); De Ponti, Elena [San Gerardo Hospital, Medical Physics, Monza (Italy); Bettinardi, Valentino; Picchio, Maria [San Raffaele Scientific Institute, Nuclear Medicine, Milan (Italy); National Research Council, Institute for Bioimaging and Molecular Physiology, Milan (Italy); Landoni, Claudio [San Raffaele Scientific Institute, Nuclear Medicine, Milan (Italy); University of Milano-Bicocca, Milan (Italy); Gilardi, Maria Carla [San Raffaele Scientific Institute, Nuclear Medicine, Milan (Italy); National Research Council, Institute for Bioimaging and Molecular Physiology, Milan (Italy); University of Milano-Bicocca, Tecnomed Foundation, Milan (Italy); Versari, Annibale [Scientific Institute Santa Maria Nuova Hospital, Nuclear Medicine, Reggio Emilia (Italy); Fioroni, Federica [Scientific Institute Santa Maria Nuova Hospital, Medical Physics, Reggio Emilia (Italy); Dziuk, Miroslaw [Masovian PET-CT Centre, Department of Nuclear Medicine, Military Institute of Medicine, Warsaw (Poland); Koza, Magdalena [Masovian PET-CT Centre, Euromedic Diagnostic, Warsaw (Poland); Ahond-Vionnet, Renee; Collin, Bertrand [Hopital Pierre Beregovoy, Service de Medecine Nucleaire, Nevers (France); Messa, Cristina [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); National Research Council, Institute for Bioimaging and Molecular Physiology, Milan (Italy); University of Milano-Bicocca, Tecnomed Foundation, Milan (Italy)

    2012-09-15

    The aim of our work is to evaluate the added diagnostic value of respiratory gated (4-D) positron emission tomography/computed tomography (PET/CT) in lung lesion detection/characterization in a large patient population of a multicentre retrospective study. The data of 155 patients (89 men, 66 women, mean age 63.9 {+-} 11.1 years) from 5 European centres and submitted to standard (3-D) and 4-D PET/CT were retrospectively analysed. Overall, 206 lung lesions were considered for the analysis (mean {+-} SD lesions dimension 14.7 {+-} 11.8 mm). Maximum standardized uptake values (SUV{sub max}) and lesion detectability were assessed for both 3-D and 4-D PET/CT studies; 3-D and 4-D PET/CT findings were compared to clinical follow-up as standard reference. Mean {+-} SD 3-D and 4-D SUV{sub max} values were 5.2 {+-} 5.1 and 6.8 {+-} 6.1 (p < 0.0001), respectively, with an average percentage increase of 30.8 %. In 3-D PET/CT, 86 of 206 (41.7 %) lesions were considered positive, 70 of 206 (34 %) negative and 50 of 206 (24.3 %) equivocal, while in 4-D PET/CT 117 of 206 (56.8 %) lesions were defined as positive, 80 of 206 (38.8 %) negative and 9 of 206 (4.4 %) equivocal. In 34 of 50 (68 %) 3-D equivocal lesions follow-up data were available and the presence of malignancy was confirmed in 21 of 34 (61.8 %) lesions, while in 13 of 34 (38.2 %) was excluded. In 31 of these 34 controlled lesions, 20 of 34 (58.8 %) and 11 of 34 (32.4 %) were correctly classified by 4-D PET/CT as positive and negative, respectively; 3 of 34 (8.8 %) remained equivocal. With equivocal lesions classified as positive, the overall accuracy of 3-D and 4-D was 85.7 and 92.8 %, respectively, while the same figures were 80.5 and 94.2 % when equivocal lesions were classified as negative. The respiratory gated PET/CT technique is a valuable clinical tool in diagnosing lung lesions, improving quantification and confidence in reporting, reducing 3-D undetermined findings and increasing the overall accuracy in lung

  1. Respiratory monitoring with an acceleration sensor

    International Nuclear Information System (INIS)

    Ono, Tomohiro; Takegawa, Hideki; Ageishi, Tatsuya; Takashina, Masaaki; Numasaki, Hodaka; Matsumoto, Masao; Teshima, Teruki

    2011-01-01

    Respiratory gating radiotherapy is used to irradiate a local area and to reduce normal tissue toxicity. There are certain methods for the detection of tumor motions, for example, using internal markers or an external respiration signal. However, because some of these respiratory monitoring systems require special or expensive equipment, respiratory monitoring can usually be performed only in limited facilities. In this study, the feasibility of using an acceleration sensor for respiratory monitoring was evaluated. The respiratory motion was represented by means of a platform and measured five times with the iPod touch (registered) at 3, 4 and 5 s periods of five breathing cycles. For these three periods of the reference waveform, the absolute means ± standard deviation (SD) of displacement were 0.45 ± 0.34 mm, 0.33 ± 0.24 mm and 0.31 ± 0.23 mm, respectively. On the other hand, the corresponding absolute means ± SD for the periods were 0.04 ± 0.09 s, 0.04 ± 0.02 s and 0.06 ± 0.04 s. The accuracy of respiratory monitoring using the acceleration sensor was satisfactory in terms of the absolute means ± SD. Using the iPod touch (registered) for respiratory monitoring does not need special equipment and makes respiratory monitoring easier. For these reasons, this system is a viable alternative to other respiratory monitoring systems.

  2. Development of deformable moving lung phantom to simulate respiratory motion in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jina [Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul 137-701 (Korea, Republic of); Lee, Youngkyu [Department of Radiation Oncology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 137-701, Seoul (Korea, Republic of); Shin, Hunjoo [Department of Radiation Oncology, Inchoen St. Mary' s Hospital College of Medicine, The Catholic University of Korea, Incheon 403-720 (Korea, Republic of); Ji, Sanghoon [Field Robot R& D Group, Korea Institute of Industrial Technology, Ansan 426-910 (Korea, Republic of); Park, Sungkwang [Department of Radiation Oncology, Busan Paik Hospital, Inje University, Busan 614-735 (Korea, Republic of); Kim, Jinyoung [Department of Radiation Oncology, Haeundae Paik Hospital, Inje University, Busan 612-896 (Korea, Republic of); Jang, Hongseok [Department of Radiation Oncology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 137-701, Seoul (Korea, Republic of); Kang, Youngnam, E-mail: ynkang33@gmail.com [Department of Radiation Oncology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 137-701, Seoul (Korea, Republic of)

    2016-07-01

    Radiation treatment requires high accuracy to protect healthy organs and destroy the tumor. However, tumors located near the diaphragm constantly move during treatment. Respiration-gated radiotherapy has significant potential for the improvement of the irradiation of tumor sites affected by respiratory motion, such as lung and liver tumors. To measure and minimize the effects of respiratory motion, a realistic deformable phantom is required for use as a gold standard. The purpose of this study was to develop and study the characteristics of a deformable moving lung (DML) phantom, such as simulation, tissue equivalence, and rate of deformation. The rate of change of the lung volume, target deformation, and respiratory signals were measured in this study; they were accurately measured using a realistic deformable phantom. The measured volume difference was 31%, which closely corresponds to the average difference in human respiration, and the target movement was − 30 to + 32 mm. The measured signals accurately described human respiratory signals. This DML phantom would be useful for the estimation of deformable image registration and in respiration-gated radiotherapy. This study shows that the developed DML phantom can exactly simulate the patient's respiratory signal and it acts as a deformable 4-dimensional simulation of a patient's lung with sufficient volume change.

  3. Development of deformable moving lung phantom to simulate respiratory motion in radiotherapy

    International Nuclear Information System (INIS)

    Kim, Jina; Lee, Youngkyu; Shin, Hunjoo; Ji, Sanghoon; Park, Sungkwang; Kim, Jinyoung; Jang, Hongseok; Kang, Youngnam

    2016-01-01

    Radiation treatment requires high accuracy to protect healthy organs and destroy the tumor. However, tumors located near the diaphragm constantly move during treatment. Respiration-gated radiotherapy has significant potential for the improvement of the irradiation of tumor sites affected by respiratory motion, such as lung and liver tumors. To measure and minimize the effects of respiratory motion, a realistic deformable phantom is required for use as a gold standard. The purpose of this study was to develop and study the characteristics of a deformable moving lung (DML) phantom, such as simulation, tissue equivalence, and rate of deformation. The rate of change of the lung volume, target deformation, and respiratory signals were measured in this study; they were accurately measured using a realistic deformable phantom. The measured volume difference was 31%, which closely corresponds to the average difference in human respiration, and the target movement was − 30 to + 32 mm. The measured signals accurately described human respiratory signals. This DML phantom would be useful for the estimation of deformable image registration and in respiration-gated radiotherapy. This study shows that the developed DML phantom can exactly simulate the patient's respiratory signal and it acts as a deformable 4-dimensional simulation of a patient's lung with sufficient volume change.

  4. Combined electrocardiography- and respiratory-triggered CT of the lung to reduce respiratory misregistration artifacts between imagining slabs in free-breathing children: Initial experience

    International Nuclear Information System (INIS)

    Goo, Hyun Woo; Allmendinger, Thomas

    2017-01-01

    Cardiac and respiratory motion artifacts degrade the image quality of lung CT in free-breathing children. The aim of this study was to evaluate the effect of combined electrocardiography (ECG) and respiratory triggering on respiratory misregistration artifacts on lung CT in free-breathing children. In total, 15 children (median age 19 months, range 6 months–8 years; 7 boys), who underwent free-breathing ECG-triggered lung CT with and without respiratory-triggering were included. A pressure-sensing belt of a respiratory gating system was used to obtain the respiratory signal. The degree of respiratory misregistration artifacts between imaging slabs was graded on a 4-point scale (1, excellent image quality) on coronal and sagittal images and compared between ECG-triggered lung CT studies with and without respiratory triggering. A p value < 0.05 was considered significant. Lung CT with combined ECG and respiratory triggering showed significantly less respiratory misregistration artifacts than lung CT with ECG triggering only (1.1 ± 0.4 vs. 2.2 ± 1.0, p = 0.003). Additional respiratory-triggering reduces respiratory misregistration artifacts on ECG-triggered lung CT in free-breathing children

  5. Combined electrocardiography- and respiratory-triggered CT of the lung to reduce respiratory misregistration artifacts between imagining slabs in free-breathing children: Initial experience

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Allmendinger, Thomas [Siemens Healthcare, GmbH, Computed Tomography Division, Forchheim (Germany)

    2017-09-15

    Cardiac and respiratory motion artifacts degrade the image quality of lung CT in free-breathing children. The aim of this study was to evaluate the effect of combined electrocardiography (ECG) and respiratory triggering on respiratory misregistration artifacts on lung CT in free-breathing children. In total, 15 children (median age 19 months, range 6 months–8 years; 7 boys), who underwent free-breathing ECG-triggered lung CT with and without respiratory-triggering were included. A pressure-sensing belt of a respiratory gating system was used to obtain the respiratory signal. The degree of respiratory misregistration artifacts between imaging slabs was graded on a 4-point scale (1, excellent image quality) on coronal and sagittal images and compared between ECG-triggered lung CT studies with and without respiratory triggering. A p value < 0.05 was considered significant. Lung CT with combined ECG and respiratory triggering showed significantly less respiratory misregistration artifacts than lung CT with ECG triggering only (1.1 ± 0.4 vs. 2.2 ± 1.0, p = 0.003). Additional respiratory-triggering reduces respiratory misregistration artifacts on ECG-triggered lung CT in free-breathing children.

  6. Beat-to-beat respiratory motion correction with near 100% efficiency: a quantitative assessment using high-resolution coronary artery imaging☆

    Science.gov (United States)

    Scott, Andrew D.; Keegan, Jennifer; Firmin, David N.

    2011-01-01

    This study quantitatively assesses the effectiveness of retrospective beat-to-beat respiratory motion correction (B2B-RMC) at near 100% efficiency using high-resolution coronary artery imaging. Three-dimensional (3D) spiral images were obtained in a coronary respiratory motion phantom with B2B-RMC and navigator gating. In vivo, targeted 3D coronary imaging was performed in 10 healthy subjects using B2B-RMC spiral and navigator gated balanced steady-state free-precession (nav-bSSFP) techniques. Vessel diameter and sharpness in proximal and mid arteries were used as a measure of respiratory motion compensation effectiveness and compared between techniques. Phantom acquisitions with B2B-RMC were sharper than those acquired with navigator gating (B2B-RMC vs. navigator gating: 1.01±0.02 mm−1 vs. 0.86±0.08 mm−1, PB2B-RMC respiratory efficiency was significantly and substantially higher (99.7%±0.5%) than nav-bSSFP (44.0%±8.9%, PB2B-RMC vs. nav-bSSFP, proximal: 1.00±0.14 mm−1 vs. 1.08±0.11 mm−1, mid: 1.01±0.11 mm−1 vs. 1.05±0.12 mm−1; both P=not significant [ns]). Mid vessel diameters were not significantly different (2.85±0.39 mm vs. 2.80±0.35 mm, P=ns), but proximal B2B-RMC diameters were slightly higher (2.85±0.38 mm vs. 2.70±0.34 mm, PB2B-RMC is less variable and significantly higher than navigator gating. Phantom and in vivo vessel sharpness and diameter values suggest that respiratory motion compensation is equally effective. PMID:21292418

  7. Beat-to-beat respiratory motion correction with near 100% efficiency: a quantitative assessment using high-resolution coronary artery imaging.

    Science.gov (United States)

    Scott, Andrew D; Keegan, Jennifer; Firmin, David N

    2011-05-01

    This study quantitatively assesses the effectiveness of retrospective beat-to-beat respiratory motion correction (B2B-RMC) at near 100% efficiency using high-resolution coronary artery imaging. Three-dimensional (3D) spiral images were obtained in a coronary respiratory motion phantom with B2B-RMC and navigator gating. In vivo, targeted 3D coronary imaging was performed in 10 healthy subjects using B2B-RMC spiral and navigator gated balanced steady-state free-precession (nav-bSSFP) techniques. Vessel diameter and sharpness in proximal and mid arteries were used as a measure of respiratory motion compensation effectiveness and compared between techniques. Phantom acquisitions with B2B-RMC were sharper than those acquired with navigator gating (B2B-RMC vs. navigator gating: 1.01±0.02 mm(-1) vs. 0.86±0.08 mm(-1), PB2B-RMC respiratory efficiency was significantly and substantially higher (99.7%±0.5%) than nav-bSSFP (44.0%±8.9%, PB2B-RMC vs. nav-bSSFP, proximal: 1.00±0.14 mm(-1) vs. 1.08±0.11 mm(-1), mid: 1.01±0.11 mm(-1) vs. 1.05±0.12 mm(-1); both P=not significant [ns]). Mid vessel diameters were not significantly different (2.85±0.39 mm vs. 2.80±0.35 mm, P=ns), but proximal B2B-RMC diameters were slightly higher (2.85±0.38 mm vs. 2.70±0.34 mm, PB2B-RMC is less variable and significantly higher than navigator gating. Phantom and in vivo vessel sharpness and diameter values suggest that respiratory motion compensation is equally effective. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Evaluation of the combined effects of target size, respiratory motion and background activity on 3D and 4D PET/CT images

    International Nuclear Information System (INIS)

    Park, Sang-June; Ionascu, Dan; Killoran, Joseph; Chin, Lee; Berbeco, Ross; Mamede, Marcelo; Gerbaudo, Victor H

    2008-01-01

    Gated (4D) PET/CT has the potential to greatly improve the accuracy of radiotherapy at treatment sites where internal organ motion is significant. However, the best methodology for applying 4D-PET/CT to target definition is not currently well established. With the goal of better understanding how to best apply 4D information to radiotherapy, initial studies were performed to investigate the effect of target size, respiratory motion and target-to-background activity concentration ratio (TBR) on 3D (ungated) and 4D PET images. Using a PET/CT scanner with 4D or gating capability, a full 3D-PET scan corrected with a 3D attenuation map from 3D-CT scan and a respiratory gated (4D) PET scan corrected with corresponding attenuation maps from 4D-CT were performed by imaging spherical targets (0.5-26.5 mL) filled with 18 F-FDG in a dynamic thorax phantom and NEMA IEC body phantom at different TBRs (infinite, 8 and 4). To simulate respiratory motion, the phantoms were driven sinusoidally in the superior-inferior direction with amplitudes of 0, 1 and 2 cm and a period of 4.5 s. Recovery coefficients were determined on PET images. In addition, gating methods using different numbers of gating bins (1-20 bins) were evaluated with image noise and temporal resolution. For evaluation, volume recovery coefficient, signal-to-noise ratio and contrast-to-noise ratio were calculated as a function of the number of gating bins. Moreover, the optimum thresholds which give accurate moving target volumes were obtained for 3D and 4D images. The partial volume effect and signal loss in the 3D-PET images due to the limited PET resolution and the respiratory motion, respectively were measured. The results show that signal loss depends on both the amplitude and pattern of respiratory motion. However, the 4D-PET successfully recovers most of the loss induced by the respiratory motion. The 5-bin gating method gives the best temporal resolution with acceptable image noise. The results based on the 4D

  9. Monte: A compact and versatile multidetector system based on monolithic telescopes

    International Nuclear Information System (INIS)

    Amorini, F.; Bonanno, A.; Cardella, G.; Di Pietro, A.; Fallica, G.; Figuera, P.; Morea, A.; Musumarra, A.; Papa, M.; Pappalardo, G.; Pinto, A.; Rizzo, F.; Tian, W.; Tudisco, S.; Valvo, G.

    2005-01-01

    We present the characteristics of a new multidetector based on monolithic silicon telescopes: MONTE. By using high-energy ion implantation techniques, the ΔE and residual energy stages of such telescopes have been integrated on the same silicon chip, obtaining extremely thin ΔE stages of the order of 1μm. This allowed one to obtain a very low charge identification energy threshold and a very good β background suppression in reactions induced by radioactive ion beams. The multidetector has a modular structure and can be assembled in different geometrical configurations according to experimental needs

  10. SU-E-T-163: Evaluation of Dose Distributions Recalculated with Per-Field Measurement Data Under the Condition of Respiratory Motion During IMRT for Liver Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Song, J; Yoon, M; Nam, T; Ahn, S; Chung, W [Chonnam National University Hwasun Hospital, Hwasun-kun, Chonnam (Korea, Republic of)

    2014-06-01

    Purpose: The dose distributions within the real volumes of tumor targets and critical organs during internal target volume-based intensity-modulated radiation therapy (ITV-IMRT) for liver cancer were recalculated by applying the effects of actual respiratory organ motion, and the dosimetric features were analyzed through comparison with gating IMRT (Gate-IMRT) plan results. Methods: The 4DCT data for 10 patients who had been treated with Gate-IMRT for liver cancer were selected to create ITV-IMRT plans. The ITV was created using MIM software, and a moving phantom was used to simulate respiratory motion. The period and range of respiratory motion were recorded in all patients from 4DCT-generated movie data, and the same period and range were applied when operating the dynamic phantom to realize coincident respiratory conditions in each patient. The doses were recalculated with a 3 dose-volume histogram (3DVH) program based on the per-field data measured with a MapCHECK2 2-dimensional diode detector array and compared with the DVHs calculated for the Gate-IMRT plan. Results: Although a sufficient prescription dose covered the PTV during ITV-IMRT delivery, the dose homogeneity in the PTV was inferior to that with the Gate-IMRT plan. We confirmed that there were higher doses to the organs-at-risk (OARs) with ITV-IMRT, as expected when using an enlarged field, but the increased dose to the spinal cord was not significant and the increased doses to the liver and kidney could be considered as minor when the reinforced constraints were applied during IMRT plan optimization. Conclusion: Because Gate-IMRT cannot always be considered an ideal method with which to correct the respiratory motional effect, given the dosimetric variations in the gating system application and the increased treatment time, a prior analysis for optimal IMRT method selection should be performed while considering the patient's respiratory condition and IMRT plan results.

  11. Interfractional changes in tumour volume and position during entire radiotherapy courses for lung cancer with respiratory gating and image guidance

    Energy Technology Data Exchange (ETDEWEB)

    Juhler-Noettrup, Trine; Korreman, Stine S.; Pedersen, Anders N.; Persson, Gitte F.; Aarup, Lasse R.; Nystroem, Haakan; Olsen, Mikael; Tarnavski, Nikolai; Specht, Lena (Dept. of Radiation Oncology, The Finsen Centre, Copenhagen (Denmark))

    2008-08-15

    Introduction. With the purpose of implementing gated radiotherapy for lung cancer patients, this study investigated the interfraction variations in tumour size and internal displacement over entire treatment courses. To explore the potential of image guided radiotherapy (IGRT) the variations were measured using a set-up strategy based on imaging of bony landmarks and compared to a strategy using in room lasers, skin tattoos and cupper landmarks. Materials and methods. During their six week treatment course of 60Gy in 2Gy fractions, ten patients underwent 3 respiratory gated CT scans. The tumours were contoured on each CT scan to evaluate the variations in volumes and position. The lung tumours and the mediastinal tumours were contoured separately. The positional variations were measured as 3D mobility vectors and correlated to matching of the scans using the two different strategies. Results. The tumour size was significantly reduced from the first to the last CT scan. For the lung tumours the reduction was 19%, p=0.03, and for the mediastinal tumours the reduction was 34%, p=0.0007. The mean 3D mobility vector and the SD for the lung tumours was 0.51cm (+-0.21) for matching using bony landmarks and 0.85cm (+-0.54) for matching using skin tattoos. For the mediastinal tumours the corresponding vectors and SD's were 0.55cm (+-0.19) and 0.72cm (+-0.43). The differences between the vectors were significant for the lung tumours p=0.004. The interfractional overlap of lung tumours was 80-87% when matched using bony landmarks and 70-76% when matched using skin tattoos. The overlap of the mediastinal tumours were 60-65% and 41-47%, respectively. Conclusions. Despite the use of gating the tumours varied considerably, regarding both position and volume. The variations in position were dependent on the set-up strategy. Set-up using IGRT was superior to set-up using skin tattoos.

  12. Interfractional changes in tumour volume and position during entire radiotherapy courses for lung cancer with respiratory gating and image guidance

    International Nuclear Information System (INIS)

    Juhler-Noettrup, Trine; Korreman, Stine S.; Pedersen, Anders N.; Persson, Gi tte F.; Aarup, Lasse R.; Nystroem, Haakan; Olsen, Mikael; Tarnavski, Nikolai; Sp echt, Lena

    2008-01-01

    Introduction. With the purpose of implementing gated radiotherapy for lung cancer patients, this study investigated the interfraction variations in tumour size and internal displacement over entire treatment courses. To explore the potential of image guided radiotherapy (IGRT) the variations were measured using a set-up strategy based on imaging of bony landmarks and compared to a strategy using in room lasers, skin tattoos and cupper landmarks. Materials and methods. During their six week treatment course of 60Gy in 2Gy fractions, ten patients underwent 3 respiratory gated CT scans. The tumours were contoured on each CT scan to evaluate the variations in volumes and position. The lung tumours and the mediastinal tumours were contoured separately. The positional variations were measured as 3D mobility vectors and correlated to matching of the scans using the two different strategies. Results. The tumour size was significantly reduced from the first to the last CT scan. For the lung tumours the reduction was 19%, p=0.03, and for the mediastinal tumours the reduction was 34%, p=0.0007. The mean 3D mobility vector and the SD for the lung tumours was 0.51cm (±0.21) for matching using bony landmarks and 0.85cm (±0.54) for matching using skin tattoos. For the mediastinal tumours the corresponding vectors and SD's were 0.55cm (±0.19) and 0.72cm (±0.43). The differences between the vectors were significant for the lung tumours p=0.004. The interfractional overlap of lung tumours was 80-87% when matched using bony landmarks and 70-76% when matched using skin tattoos. The overlap of the mediastinal tumours were 60-65% and 41-47%, respectively. Conclusions. Despite the use of gating the tumours varied considerably, regarding both position and volume. The variations in position were dependent on the set-up strategy. Set-up using IGRT was superior to set-up using skin tattoos

  13. Respiratory motion-resolved, self-gated 4D-MRI using Rotating Cartesian K-space (ROCK): Initial clinical experience on an MRI-guided radiotherapy system.

    Science.gov (United States)

    Han, Fei; Zhou, Ziwu; Du, Dongsu; Gao, Yu; Rashid, Shams; Cao, Minsong; Shaverdian, Narek; Hegde, John V; Steinberg, Michael; Lee, Percy; Raldow, Ann; Low, Daniel A; Sheng, Ke; Yang, Yingli; Hu, Peng

    2018-06-01

    To optimize and evaluate the respiratory motion-resolved, self-gated 4D-MRI using Rotating Cartesian K-space (ROCK-4D-MRI) method in a 0.35 T MRI-guided radiotherapy (MRgRT) system. The study included seven patients with abdominal tumors treated on the MRgRT system. ROCK-4D-MRI and 2D-CINE, was performed immediately after one of the treatment fractions. Motion quantification based on 4D-MRI was compared with those based on 2D-CINE. The image quality of 4D-MRI was evaluated against 4D-CT. The gross tumor volumes (GTV) were defined based on individual respiratory phases of both 4D-MRI and 4D-CT and compared for their variability over the respiratory cycle. The motion measurements based on 4D-MRI matched well with 2D-CINE, with differences of 1.04 ± 0.52 mm in the superior-inferior and 0.54 ± 0.21 mm in the anterior-posterior directions. The image quality scores of 4D-MRI were significantly higher than 4D-CT, with better tumor contrast (3.29 ± 0.76 vs. 1.86 ± 0.90) and less motion artifacts (3.57 ± 0.53 vs. 2.29 ± 0.95). The GTVs were more consistent in 4D-MRI than in 4D-CT, with significantly smaller GTV variability (9.31 ± 4.58% vs. 34.27 ± 23.33%). Our study demonstrated the clinical feasibility of using the ROCK-4D-MRI to acquire high quality, respiratory motion-resolved 4D-MRI in a low-field MRgRT system. The 4D-MRI image could provide accurate dynamic information for radiotherapy treatment planning. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Extracting a respiratory signal from raw dynamic PET data that contain tracer kinetics.

    Science.gov (United States)

    Schleyer, P J; Thielemans, K; Marsden, P K

    2014-08-07

    Data driven gating (DDG) methods provide an alternative to hardware based respiratory gating for PET imaging. Several existing DDG approaches obtain a respiratory signal by observing the change in PET-counts within specific regions of acquired PET data. Currently, these methods do not allow for tracer kinetics which can interfere with the respiratory signal and introduce error. In this work, we produced a DDG method for dynamic PET studies that exhibit tracer kinetics. Our method is based on an existing approach that uses frequency-domain analysis to locate regions within raw PET data that are subject to respiratory motion. In the new approach, an optimised non-stationary short-time Fourier transform was used to create a time-varying 4D map of motion affected regions. Additional processing was required to ensure that the relationship between the sign of the respiratory signal and the physical direction of movement remained consistent for each temporal segment of the 4D map. The change in PET-counts within the 4D map during the PET acquisition was then used to generate a respiratory curve. Using 26 min dynamic cardiac NH3 PET acquisitions which included a hardware derived respiratory measurement, we show that tracer kinetics can severely degrade the respiratory signal generated by the original DDG method. In some cases, the transition of tracer from the liver to the lungs caused the respiratory signal to invert. The new approach successfully compensated for tracer kinetics and improved the correlation between the data-driven and hardware based signals. On average, good correlation was maintained throughout the PET acquisitions.

  15. Video-coaching as biofeedback tool to improve gated treatments. Possibilities and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Cossmann, Peter H. [Medtech Consulting Cossmann, Wettingen (Switzerland); Private Univ. im Fuerstentum Liechtenstein, Triesen (Liechtenstein)

    2012-11-01

    For respiratory gated radiotherapy the manufacturers of linear accelerators offer dedicated gating technologies. The video-based Varian RPM Gating system (Varian Medical Systems, Palo Alto/CA, USA) includes in a standard configuration a support tool for regular breathing called audiocoaching. As this approach has limitations regarding direct control of the patient's breathing due to a missing feedback, we designed an additional tool offering videocoaching. In order to evaluate the impact of this additional functionality, we measured parameters defining the image quality of 4D-CT data as well as the treatment duration which is mainly influenced by the patient's limited ability to achieve a stable breathing pattern. (orig.)

  16. SU-E-J-235: Audiovisual Biofeedback Improves the Correlation Between Internal and External Respiratory Motion

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D; Pollock, S; Keall, P [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, NSW (Australia); Greer, P [School of Mathematical and Physical Sciences, The University of Newcastle, Newcastle, NSW (Australia); Department of Radiation Oncology, Calvary Mater Newcastle, Newcastle, NSW (Australia); Ludbrook, J [Department of Radiation Oncology, Calvary Mater Newcastle, Newcastle, NSW (Australia); Paganelli, C [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano (Italy); Kim, T [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, NSW (Australia); Department of Radiation Oncology, University of Virginia Health System, Charlottesville, NC (United States)

    2015-06-15

    Purpose: External respiratory surrogates are often used to predict internal lung tumor motion for beam gating but the assumption of correlation between external and internal surrogates is not always verified resulting in amplitude mismatch and time shift. To test the hypothesis that audiovisual (AV) biofeedback improves the correlation between internal and external respiratory motion, in order to improve the accuracy of respiratory-gated treatments for lung cancer radiotherapy. Methods: In nine lung cancer patients, 2D coronal and sagittal cine-MR images were acquired across two MRI sessions (pre- and mid-treatment) with (1) free breathing (FB) and (2) AV biofeedback. External anterior-posterior (AP) respiratory motions of (a) chest and (b) abdomen were simultaneously acquired with physiological measurement unit (PMU, 3T Skyra, Siemens Healthcare Erlangen, Germany) and real-time position management (RPM) system (Varian, Palo Alto, USA), respectively. Internal superior-inferior (SI) respiratory motions of (c) lung tumor (i.e. centroid of auto-segmented lung tumor) and (d) diaphragm (i.e. upper liver dome) were measured from individual cine-MR images across 32 dataset. The four respiratory motions were then synchronized with the cine-MR image acquisition time. Correlation coefficients were calculated in the time variation of two nominated respiratory motions: (1) chest-abdomen, (2) abdomen-diaphragm and (3) diaphragm-lung tumor. The three combinations were compared between FB and AV biofeedback. Results: Compared to FB, AV biofeedback improved chest-abdomen correlation by 17% (p=0.005) from 0.75±0.23 to 0.90±0.05 and abdomen-diaphragm correlation by 4% (p=0.058) from 0.91±0.11 to 0.95±0.05. Compared to FB, AV biofeedback improved diaphragm-lung tumor correlation by 12% (p=0.023) from 0.65±0.21 to 0.74±0.16. Conclusions: Our results demonstrated that AV biofeedback significantly improved the correlation of internal and external respiratory motion, thus

  17. SU-E-J-235: Audiovisual Biofeedback Improves the Correlation Between Internal and External Respiratory Motion

    International Nuclear Information System (INIS)

    Lee, D; Pollock, S; Keall, P; Greer, P; Ludbrook, J; Paganelli, C; Kim, T

    2015-01-01

    Purpose: External respiratory surrogates are often used to predict internal lung tumor motion for beam gating but the assumption of correlation between external and internal surrogates is not always verified resulting in amplitude mismatch and time shift. To test the hypothesis that audiovisual (AV) biofeedback improves the correlation between internal and external respiratory motion, in order to improve the accuracy of respiratory-gated treatments for lung cancer radiotherapy. Methods: In nine lung cancer patients, 2D coronal and sagittal cine-MR images were acquired across two MRI sessions (pre- and mid-treatment) with (1) free breathing (FB) and (2) AV biofeedback. External anterior-posterior (AP) respiratory motions of (a) chest and (b) abdomen were simultaneously acquired with physiological measurement unit (PMU, 3T Skyra, Siemens Healthcare Erlangen, Germany) and real-time position management (RPM) system (Varian, Palo Alto, USA), respectively. Internal superior-inferior (SI) respiratory motions of (c) lung tumor (i.e. centroid of auto-segmented lung tumor) and (d) diaphragm (i.e. upper liver dome) were measured from individual cine-MR images across 32 dataset. The four respiratory motions were then synchronized with the cine-MR image acquisition time. Correlation coefficients were calculated in the time variation of two nominated respiratory motions: (1) chest-abdomen, (2) abdomen-diaphragm and (3) diaphragm-lung tumor. The three combinations were compared between FB and AV biofeedback. Results: Compared to FB, AV biofeedback improved chest-abdomen correlation by 17% (p=0.005) from 0.75±0.23 to 0.90±0.05 and abdomen-diaphragm correlation by 4% (p=0.058) from 0.91±0.11 to 0.95±0.05. Compared to FB, AV biofeedback improved diaphragm-lung tumor correlation by 12% (p=0.023) from 0.65±0.21 to 0.74±0.16. Conclusions: Our results demonstrated that AV biofeedback significantly improved the correlation of internal and external respiratory motion, thus

  18. The value of unenhanced multi-detector computed tomography ...

    African Journals Online (AJOL)

    Introduction: Unenhanced computed tomography (CT) is used to detect urinary tract calculi with high accuracy. The development of multi-detector CT (MDCT) allows reconstructions in coronal, sagittal and oblique directions. Objective: To compare MDCT with three-dimensional (3D) ultrasound (US) imaging in evaluating ...

  19. SU-F-T-526: A Comparative Study On Gating Efficiency of Varian RPM Device and Calypso System

    Energy Technology Data Exchange (ETDEWEB)

    Ravindran, P [Christian Medical College Hospital, Vellore (India); Wui Ann, W; Lim, Y [The Brunei Cancer Center (Brunei Darussalam)

    2016-06-15

    Purpose: In general, the linear accelerator is gated using respiratory signal obtained by way of external sensors to account for the breathing motion during radiotherapy. One of the commonly used gating devices is the Varian RPM device. Calypso system that uses electromagnetic tracking of implanted or surface transponders could also be used for gating. The aim of this study is to compare the gating efficiency of RPM device and the calypso system by phantom studies. Methods: An ArcCheck insert was used as the phantom with a Gafchromic film placed in its holder. The ArcCheck insert was placed on a Motion Sim platform and moved in the longitudinal direction simulating a respiratory motion with a period of 5 seconds and amplitude of ±6mm. The Gafchromic film was exposed to a 2 × 2cm{sup 2} field, i) with the phantom static, ii) phantom moving but ungated iii) gated with gating window of 2mm and 3mm. This was repeated with Calypso system using surface transponders with the same gating window. The Gafchromic films were read with an EPSON 11000 flatbed scanner and analysed with ‘Medphysto’ software. Results: The full width at half maximum (FWHM) as measured with film at the level of the film holder was 1.65cm when the phantom was static. FWHM measured with phantom moving and without gating was 1.16 cm and penumbra was 7 mm (80–20%) on both sides. When the beam was gated with 2 mm gating window the FWHM was 1.8 cm with RPM device and 1.9 cm with Calypso. Similarly, when the beam was gated with 3 mm window, the FWHM was 1.9cm with RPM device and 2cm with Calypso. Conclusion: This work suggests that the gating efficiency of RPM device is better than that of the Calypso with surface transponder, with reference to the latency in gating.

  20. Multidetector-row computed tomography of thoracic aortic anomalies in dogs and cats: Patent ductus arteriosus and vascular rings

    Directory of Open Access Journals (Sweden)

    Nolte Ingo

    2011-09-01

    Full Text Available Abstract Background Diagnosis of extracardiac intrathoracic vascular anomalies is of clinical importance, but remains challenging. Traditional imaging modalities, such as radiography, echocardiography, and angiography, are inherently limited by the difficulties of a 2-dimensional approach to a 3-dimensional object. We postulated that accurate characterization of malformations of the aorta would benefit from 3-dimensional assessment. Therefore, multidetector-row computed tomography (MDCT was chosen as a 3-dimensional, new, and noninvasive imaging technique. The purpose of this study was to evaluate patients with 2 common diseases of the intrathoracic aorta, either patent ductus arteriosus or vascular ring anomaly, by contrast-enhanced 64-row computed tomography. Results Electrocardiography (ECG-gated and thoracic nongated MDCT images were reviewed in identified cases of either a patent ductus arteriosus or vascular ring anomaly. Ductal size and morphology were determined in 6 dogs that underwent ECG-gated MDCT. Vascular ring anomalies were characterized in 7 dogs and 3 cats by ECG-gated MDCT or by a nongated thoracic standard protocol. Cardiac ECG-gated MDCT clearly displayed the morphology, length, and caliber of the patent ductus arteriosus in 6 affected dogs. Persistent right aortic arch was identified in 10 animals, 8 of which showed a coexisting aberrant left subclavian artery. A mild dilation of the proximal portion of the aberrant subclavian artery near its origin of the aorta was present in 4 dogs, and a diverticulum analogous to the human Kommerell's diverticulum was present in 2 cats. Conclusions Contrast-enhanced MDCT imaging of thoracic anomalies gives valuable information about the exact aortic arch configuration. Furthermore, MDCT was able to characterize the vascular branching patterns in dogs and cats with a persistent right aortic arch and the morphology and size of the patent ductus arteriosus in affected dogs. This additional

  1. Comparison of gated blood pool SPECT and spiral multidetector computed tomography in the assessment of right ventricular functional parameters. Validation with first-pass radionuclide angiography

    International Nuclear Information System (INIS)

    Lee, Jung S.; Kim, Seong-Jang; Kim, In-Ju; Kim, Yong-Ki; Choo, Ki S.; Lee, Jun S.

    2007-01-01

    The aim of this study was to compare gated blood pool single photon emission computed tomography (SPECT) (GBPS) and multidetector row computed tomography (MDCT) for the determination of right ventricular ejection fraction (RVEF) and right ventricular volumes (RVV) and to compare first-pass radionuclide angiography (FP-RNA) as the gold standard. Twenty consecutive patients (11 men, 9 women) referred for MDCT for the evaluation of the presence of coronary artery disease underwent FP-RNA and GBPS. The mean right ventricular end-diastolic volume (EDV) calculated with GBPS revealed a statistically significant lower value than that of MDCT. The mean right ventricular end-systolic volume (ESV) calculated with GBPS was also lower than that of MDCT. A comparison of right ventricular EDV from GBPS and MDCT yielded a correlation coefficient of 0.5972. Right ventricular ESV between GBPS and MDCT showed a correlation coefficient of 0.5650. The mean RVEFs calculated with FP-RNA (39.8%±4.0%), GBPS (43.7%±6.9%), and MDCT (40.4%±7.7%) showed no statistical differences (Kruskal-Wallis statistics 4.538, P=0.1034). A comparison of RVEFs from FP-RNA and GBPS yielded a correlation coefficient of 0.7251; RVEFs between FP-RNA and MDCT showed a correlation coefficient of 0.6166 and between GBPS and MDCT showed a correlation coefficient of 0.6367. The RVEF, EDV, and ESV calculated by GBPS had good correlation with those obtained with MDCT. In addition, there were no statistical differences of RVEF calculated from FP-RNA, GBPS, and MDCT. However, with regard to RVV, EDV and ESV from GBPS revealed statistically significantly lower values than those of MDCT. Although reasonable correlations among these modalities were obtained, the agreement among these three modalities was not good enough for interchangeable use in the clinical setting. Also, these results should be confirmed in patients with cardiac diseases in future larger population-based studies. (author)

  2. Congenital coronary artery anomalies: diagnosis with 64 slice multidetector row computed tomography coronary angiography: A single Centre Study

    International Nuclear Information System (INIS)

    Srnivasan, K.G.; Gaikward, A.; Kannan, B.R.J.; Ritesh, K.; Ushanandini, K.P.

    2008-01-01

    Full text: Retrospective review of the congenital coronary artery (CA) anomalies detected by a 64-slice multidetector row computed tomographic (MDCT) angiography. The type of the anomaly, imaging characteristics, clinical relevance and the superiority of the MDCT over conventional coronary angiography are discussed. Multidetector row computed tomographic coronary angiography was carried out by the usual technique with 70 cc of non-ionic contrast agent and retrospective electrocardiogram gating. The volume data obtained were reconstructed in axial plane, along with volume-rendered three-dimensional reconstruction and virtual angioscopy in selected patients. The images were analysed by a radiologist, experienced in cardiac CT, and an experienced cardiologist. A retrospective review of the records was carried out, and subjects with congenital coronary anomalies were included in the study. Between 15 November 2005 and 27 February 2007, 1495 MDCT coronary angiograms were carried out. Eleven of them were found to have coronary anomalies. Five had absent left main CA. Two had interarterial course of the left main CA artery passing in between the right ventricular outflow tract and the root of aorta. In one patient, there was aberrant origin of right CA from the left aortic sinus with subsequent interarterial course and another one had aberrant origin of circumflex artery from the right aortic sinus. One patient each of congenitally absent circumflex artery and atresia of the right CA were found. Sixty-four slice MDCT coronary angiography provided accurate depiction of anomalous vessel origin and course along with the complex anatomical relation with the adjacent structures. CTcan be considered as a first-line imaging method for delineating coronary arterial anomalies.

  3. Usefulness of multi-detector row Computed Tomography for ...

    African Journals Online (AJOL)

    A 74-year-old female underwent surgical treatment for adenocarcinoma of the pancreatic head. Preoperative multi-detector row computed tomography (MD-CT) demonstrated tumor invasion into the accessory right colic vein and the branch of the middle colic artery (MCA), which was not detected by digital subtraction ...

  4. A multidetector tomography protocol for follow-up of endovascular aortic aneurysm repair

    Directory of Open Access Journals (Sweden)

    Roberto Moraes Bastos

    2011-01-01

    Full Text Available OBJECTIVE: The purpose of this study was to improve the use of 64-channel multidetector computed tomography using lower doses of ionizing radiation during follow-up procedures in a series of patients with endovascular aortic aneurysm repair. METHODS: Thirty patients receiving 5 to 29 months of follow-up after endovascular aortic aneurysm repair were analyzed using a 64-channel multidetector computed tomography device by an exam that included pre-and postcontrast with both arterial and venous phases. Leak presence and type were classified based on the exam phase. RESULTS: Endoleaks were identified in 8/30 of cases; the endoleaks in 3/8 of these cases were not visible in the arterial phases of the exams. CONCLUSION: The authors conclude that multidetector computed tomography with pre-contrast and venous phases should be a part of the ongoing follow-up of patients undergoing endovascular aortic aneurysm repair. The arterial phase can be excluded when the aneurism is stable or regresses. These findings permit a lower radiation dose without jeopardizing the correct diagnosis of an endoleak.

  5. Comparative evaluation of CT-based and respiratory-gated PET/CT-based planning target volume (PTV) in the definition of radiation treatment planning in lung cancer: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, Luca; Elisei, Federica [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); Meregalli, Sofia; Niespolo, Rita [San Gerardo Hospital, Radiotherapy, Monza (Italy); Zorz, Alessandra; De Ponti, Elena; Morzenti, Sabrina; Crespi, Andrea [San Gerardo Hospital, Medical Physics, Monza (Italy); Brenna, Sarah [University of Milan-Bicocca, School of Radiation Oncology, Monza (Italy); Gardani, Gianstefano [San Gerardo Hospital, Radiotherapy, Monza (Italy); University of Milan-Bicocca, Milan (Italy); Messa, Cristina [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); University of Milan-Bicocca, Tecnomed Foundation, Milan (Italy); National Research Council, Institute for Bioimaging and Molecular Physiology, Milan (Italy)

    2014-04-15

    The aim of this study was to compare planning target volume (PTV) defined on respiratory-gated positron emission tomography (PET)/CT (RG-PET/CT) to PTV based on ungated free-breathing CT and to evaluate if RG-PET/CT can be useful to personalize PTV by tailoring the target volume to the lesion motion in lung cancer patients. Thirteen lung cancer patients (six men, mean age 70.0 years, 1 small cell lung cancer, 12 non-small cell lung cancer) who were candidates for radiation therapy were prospectively enrolled and submitted to RG-PET/CT. Ungated free-breathing CT images obtained during a PET/CT study were visually contoured by the radiation oncologist to define standard clinical target volumes (CTV1). Standard PTV (PTV1) resulted from CTV1 with the addition of 1-cm expansion of margins in all directions. RG-PET/CT images were contoured by the nuclear medicine physician and radiation oncologist according to a standardized institutional protocol for contouring gated images. Each CT and PET image of the patient's respiratory cycle phases was contoured to obtain the RG-CT-based CTV (CTV2) and the RG-PET/CT-based CTV (CTV3), respectively. RG-CT-based and RG-PET/CT-based PTV (PTV2 and PTV3, respectively) were then derived from gated CTVs with a margin expansion of 7-8 mm in head to feet direction and 5 mm in anterior to posterior and left to right direction. The portions of gated PTV2 and PTV3 geometrically not encompassed in PTV1 (PTV2 out PTV1 and PTV3 out PTV1) were also calculated. Mean ± SD CTV1, CTV2 and CTV3 were 30.5 ± 33.2, 43.1 ± 43.2 and 44.8 ± 45.2 ml, respectively. CTV1 was significantly smaller than CTV2 and CTV3 (p = 0.017 and 0.009 with Student's t test, respectively). No significant difference was found between CTV2 and CTV3. Mean ± SD of PTV1, PTV2 and PTV3 were 118.7 ± 94.1, 93.8 ± 80.2 and 97.0 ± 83.9 ml, respectively. PTV1 was significantly larger than PTV2 and PTV3 (p = 0.038 and 0.043 with Student's t test, respectively). No

  6. High-resolution imaging of pulmonary ventilation and perfusion with 68Ga-VQ respiratory gated (4-D) PET/CT

    International Nuclear Information System (INIS)

    Callahan, Jason; Hofman, Michael S.; Siva, Shankar; Kron, Tomas; Schneider, Michal E.; Binns, David; Eu, Peter; Hicks, Rodney J.

    2014-01-01

    Our group has previously reported on the use of 68 Ga-ventilation/perfusion (VQ) PET/CT scanning for the diagnosis of pulmonary embolism. We describe here the acquisition methodology for 68 Ga-VQ respiratory gated (4-D) PET/CT and the effects of respiratory motion on image coregistration in VQ scanning. A prospective study was performed in 15 patients with non-small-cell lung cancer. 4-D PET and 4-D CT images were acquired using an infrared marker on the patient's abdomen as a surrogate for breathing motion following inhalation of Galligas and intravenous administration of 68 Ga-macroaggregated albumin. Images were reconstructed with phase-matched attenuation correction. The lungs were contoured on CT and PET VQ images during free-breathing (FB) and at maximum inspiration (Insp) and expiration (Exp). The similarity between PET and CT volumes was measured using the Dice coefficient (DC) comparing the following groups; (1) FB-PET/CT, (2) InspPET/InspCT, (3) ExpPET/Exp CT, and (4) FB-PET/AveCT. A repeated measures one-way ANOVA with multiple comparison Tukey tests were performed to evaluate any difference between the groups. Diaphragmatic motion in the superior-inferior direction on the 4-D CT scan was also measured. 4-D VQ scanning was successful in all patients without additional acquisition time compared to the nongated technique. The highest volume overlap was between ExpPET and ExpCT and between FB-PET and AveCT with a DC of 0.82 and 0.80 for ventilation and perfusion, respectively. This was significantly better than the DC comparing the other groups (0.78-0.79, p 68 Ga-VQ 4-D PET/CT is feasible and the blurring caused by respiratory motion is well corrected with 4-D acquisition, which principally reduces artefact at the lung bases. The images with the highest spatial overlap were the combined expiration phase or FB PET and average CT. With higher resolution than SPECT/CT, the PET/CT technique has a broad range of potential clinical applications including

  7. Extracting a respiratory signal from raw dynamic PET data that contain tracer kinetics

    International Nuclear Information System (INIS)

    Schleyer, P J; Thielemans, K; Marsden, P K

    2014-01-01

    Data driven gating (DDG) methods provide an alternative to hardware based respiratory gating for PET imaging. Several existing DDG approaches obtain a respiratory signal by observing the change in PET-counts within specific regions of acquired PET data. Currently, these methods do not allow for tracer kinetics which can interfere with the respiratory signal and introduce error. In this work, we produced a DDG method for dynamic PET studies that exhibit tracer kinetics. Our method is based on an existing approach that uses frequency-domain analysis to locate regions within raw PET data that are subject to respiratory motion. In the new approach, an optimised non-stationary short-time Fourier transform was used to create a time-varying 4D map of motion affected regions. Additional processing was required to ensure that the relationship between the sign of the respiratory signal and the physical direction of movement remained consistent for each temporal segment of the 4D map. The change in PET-counts within the 4D map during the PET acquisition was then used to generate a respiratory curve. Using 26 min dynamic cardiac NH 3 PET acquisitions which included a hardware derived respiratory measurement, we show that tracer kinetics can severely degrade the respiratory signal generated by the original DDG method. In some cases, the transition of tracer from the liver to the lungs caused the respiratory signal to invert. The new approach successfully compensated for tracer kinetics and improved the correlation between the data-driven and hardware based signals. On average, good correlation was maintained throughout the PET acquisitions. (paper)

  8. Doses of Coronary Study in 64 Channel Multi-Detector Computed Tomography : Reduced Radiation Dose According to Varity of Examnination Protocols

    International Nuclear Information System (INIS)

    Kim, Moon Chan

    2009-01-01

    To compare radiation dose for coronary CT angiography (CTA) obtained with 6 examination protocols such as a retrospectively ECG gated helical scan, a prospectively ECG gated sequential scan, low kVp technique, and cardiac dose modulation technique. Coronary CTA was performed by using 6 current clinical protocols to evaluate effective dose and organ dose in primary beam area with anthropomorphic female phantom and glass dosimetric system in 64 channel multi-detector CT. After acquiring topograms of frontal and lateral projection with 80 kVp and 10 mA, main coronary scan was done with 0.35 sec tube rotation time, 40 mm collimation (0.625 mm x 64 ea), small scan field of view (32 cm diameter), 105 mm scan length. Heart beat rate of phantom was maintained 60 bpm in ECG gating. In constant mAs technique 120 kVp, 600 mA was used, and 100 kVp for low kVp technique. In a retrospectively ECG gated helical CT technique 0.22 pitch was used, peak mA (600 mA) was adopted in range of 40-80% of R-R interval and 120 mA (80% reduction) in others with cardiac dose modulation. And 210 mAs was used without cardiac dose modulation. In a prospectively ECG gated sequential CT technique data were acquired at 75% R-R interval (middle diastolic phase in cardiac cycle), and 120 msec additional padding of the tube-on time was used. For effective dose calculation region specific conversion factor of dose length product in thorax was used, which was recommended by EUR 16262. The mean effective dose for conventional coronary CTA without cardiac dose modulation in a retrospectively ECG gated helical scan was 17.8 mSv, and mean organ dose of heart was 103.8 mGy. With low kVp and cardiac dose modulation the mean effective dose showed 54.5% reduction, and heart dose showed 52.3% reduction, compared with that of conventional coronary CTA. And at the sequential scan(SnapShot pulse mode) under prospective ECG gating the mean effective dose was 4.9 mSv, this represents an 72.5% reduction compared with

  9. Multi-detector CT assessment of traumatic renal lesions

    African Journals Online (AJOL)

    Mohamed Samir Shaaban

    2015-07-10

    Jul 10, 2015 ... Aim of the work: To demonstrate different traumatic lesions of the kidneys using multi-detector. CT, and its use in ... sis and staging of renal trauma and guiding management. © 2015 The ... Emotion 6 (Siemens, Germany), and 16 detectors PHILIPS .... with active bleeding within the hematoma and was man-.

  10. Development and clinical application of respiration gated irradiation system (ReGIS) in heavy ion radiotherapy

    International Nuclear Information System (INIS)

    Osaka, Yasuhiro; Tsujii, Hirohiko; Mizoe, Jun-etsu

    1999-01-01

    In order to achieve maximal radiation dose concentration for thoraco-abdominal tumors and spare normal surrounding tissue in heavy ion therapy, compensation for respiration-related movement is desirable. Hence, a respiration-gated irradiation system (ReGIS) was introduced to the Heavy Ion Medical Accelerator in Chiba (HIMAC) in June 1996. In this report, the development and clinical application of ReGIS, as well as the analysis of respiration-related movement and reduction of target volumes are described. When using ReGIS, a sensor emitting infrared rays is attached to the thoracic or abdominal wall to measure respiratory movement. A position-sensitive device (camera) senses these rays to detect sensor locations and data are forwarded to a computer system. A curve representing respiratory cycles is displayed, upon which a trigger level that is part of a respiratory cycle (about a fourth or fifth of the expiratory phase). Beams can be delivered while the respiratory curve is under the trigger level. Thirty-five patients involving 37 irradiated sites (19 lung cancers, 13 hepatomas, 2 mediastinal tumors, and 3 metastatic lung tumors) were retrospectively analyzed. Target volumes were reduced an average of 29.5% (11.0 to 57.9%) using ReGIS. Average tumor respiration-related movement in gated phase was 3.7 mm (0 mm to 14.6 mm). Although irradiation using ReGIS took more time to perform (average 1.62 times non-gated irradiation), it was considered to be acceptable for routine heavy ion therapy. ReGIS has proved to be useful for compensation of respiration-related movement and reduction of target volume in radiotherapy, and this method is sufficiently simple for practical clinical application. (author)

  11. Motion management during IMAT treatment of mobile lung tumors-A comparison of MLC tracking and gated delivery

    DEFF Research Database (Denmark)

    Falk, Marianne; Pommer, Tobias; Keall, Paul

    2014-01-01

    Purpose:To compare real-time dynamic multileaf collimator (MLC) tracking, respiratory amplitude and phase gating, and no compensation for intrafraction motion management during intensity modulated arc therapy (IMAT). Methods: Motion management with MLC tracking and gating was evaluated for four...... tracking reduced the effects of the target movements, although the gated delivery showed a better dosimetric accuracy and enabled a larger reduction of the margins in some cases. MLC tracking did not prolong the treatment time compared to delivery with no motion compensation while gating had a considerably...... of the dosimetric error contributions showed that the gated delivery mainly had errors in target localization, while MLC tracking also had contributions from MLC leaf fitting and leaf adjustment. The average treatment time was about three times longer with gating compared to delivery with MLC tracking (that did...

  12. Gated Treatment Delivery Verification With On-Line Megavoltage Fluoroscopy

    International Nuclear Information System (INIS)

    Tai An; Christensen, James D.; Gore, Elizabeth; Khamene, Ali; Boettger, Thomas; Li, X. Allen

    2010-01-01

    Purpose: To develop and clinically demonstrate the use of on-line real-time megavoltage (MV) fluoroscopy for gated treatment delivery verification. Methods and Materials: Megavoltage fluoroscopy (MVF) image sequences were acquired using a flat panel equipped for MV cone-beam CT in synchrony with the respiratory signal obtained from the Anzai gating device. The MVF images can be obtained immediately before or during gated treatment delivery. A prototype software tool (named RTReg4D) was developed to register MVF images with phase-sequenced digitally reconstructed radiograph images generated from the treatment planning system based on four-dimensional CT. The image registration can be used to reposition the patient before or during treatment delivery. To demonstrate the reliability and clinical usefulness, the system was first tested using a thoracic phantom and then prospectively in actual patient treatments under an institutional review board-approved protocol. Results: The quality of the MVF images for lung tumors is adequate for image registration with phase-sequenced digitally reconstructed radiographs. The MVF was found to be useful for monitoring inter- and intrafractional variations of tumor positions. With the planning target volume contour displayed on the MVF images, the system can verify whether the moving target stays within the planning target volume margin during gated delivery. Conclusions: The use of MVF images was found to be clinically effective in detecting discrepancies in tumor location before and during respiration-gated treatment delivery. The tools and process developed can be useful for gated treatment delivery verification.

  13. Model-based respiratory motion compensation for emission tomography image reconstruction

    International Nuclear Information System (INIS)

    Reyes, M; Malandain, G; Koulibaly, P M; Gonzalez-Ballester, M A; Darcourt, J

    2007-01-01

    In emission tomography imaging, respiratory motion causes artifacts in lungs and cardiac reconstructed images, which lead to misinterpretations, imprecise diagnosis, impairing of fusion with other modalities, etc. Solutions like respiratory gating, correlated dynamic PET techniques, list-mode data based techniques and others have been tested, which lead to improvements over the spatial activity distribution in lungs lesions, but which have the disadvantages of requiring additional instrumentation or the need of discarding part of the projection data used for reconstruction. The objective of this study is to incorporate respiratory motion compensation directly into the image reconstruction process, without any additional acquisition protocol consideration. To this end, we propose an extension to the maximum likelihood expectation maximization (MLEM) algorithm that includes a respiratory motion model, which takes into account the displacements and volume deformations produced by the respiratory motion during the data acquisition process. We present results from synthetic simulations incorporating real respiratory motion as well as from phantom and patient data

  14. Congenital anomalies of the coronary arteries: imaging with contrast-enhanced, multidetector computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Rainer; Froehner, Steffen; Wagner, Matthias; Brunner, Horst; Cherevatyy, Oleg; Christopoulos, Georgios [Herz- und Gefaessklinik GmbH, Department of Radiology, Bad Neustadt an der Saale (Germany); Brunn, Juergen; Gietzen, Frank; Kerber, Sebastian [Herz- und Gefaessklinik GmbH, Department of Cardiology, Bad Neustadt an der Saale (Germany); Fellner, Franz [Oberoesterreichische Landesnervenklinik, Department of Radiology, Linz (Austria)

    2005-06-01

    The objective of this study is to evaluate multidetector CT (MDCT) in detecting and characterizing anomalous coronary arteries. Forty-four patients with anomalies of the coronaries were selected from a total of 1758 individuals examined with ECG-gated 4- and 16-row MDCT including thin MIP, MPR and VRT post-processing. Twenty-eight patients showed origin and course anomalies of the central coronary segments, and in this subgroup 13 were judged as ''malignant'' because of interarterial courses between the aortic root and the pulmonary trunk, either of the right coronary artery (n=11) or the left coronary artery (n=2). Twelve non-hemodynamic anomalies were found, affecting the coronary origins only (n=10) or the peripheral vessels courses (n=2). Four arteriovenous fistulas were present, all of them with complex arterial feeders. Regardless of vessel anatomy, coronary opacification was always possible by means of the systemic contrast agent, and the aberrant coronary arteries were visualized synoptically in direct relation to the great mediastinal vessels. In contrast to MDCT, selective cannulation and final diagnosis was possible in only 11 of the 20 catheter angiograms performed (accuracy of 55.0%). In conclusion, its non-invasiveness and precise visualization makes MDCT the standard of reference for evaluating anomalous coronary arteries. (orig.)

  15. Respiratory-Gated Proton Beam Therapy for Hepatocellular Carcinoma Adjacent to the Gastrointestinal Tract without Fiducial Markers

    Directory of Open Access Journals (Sweden)

    Miu Mizuhata

    2018-02-01

    Full Text Available The efficacy of proton beam therapy (PBT for hepatocellular carcinoma (HCC has been reported, but insertion of fiducial markers in the liver is usually required. We evaluated the efficacy and toxicity of respiratory-gated PBT without fiducial markers for HCC located within 2 cm of the gastrointestinal tract. From March 2011 to December 2015 at our institution, 40 patients were evaluated (median age, 72 years; range, 38–87 years. All patients underwent PBT at a dose of 60 to 80 cobalt gray equivalents (CGE in 20 to 38 fractions. The median follow-up period was 19.9 months (range, 1.2–72.3 months. The median tumor size was 36.5 mm (range, 11–124 mm. Kaplan–Meier estimates of the 2-year overall survival, progression-free survival, and local tumor control rates were 76%, 60%, and 94%, respectively. One patient (2.5% developed a grade 3 gastric ulcer and one (2.5% developed grade 3 ascites retention; none of the remaining patients developed grade >3 toxicities (National Cancer Institute Common Terminology Criteria for Adverse Events ver. 4.0.. This study indicates that PBT without fiducial markers achieves good local control without severe treatment-related toxicity of the gastrointestinal tract for HCC located within 2 cm of the gastrointestinal tract.

  16. Evaluation of secondary spontaneous pneumothorax with multidetector CT

    International Nuclear Information System (INIS)

    Hilliard, N.J.; Marciniak, S.J.; Babar, J.L.; Balan, A.

    2013-01-01

    The purpose of this article is to review the underlying causes of secondary pneumothoraces as observed on multidetector computed tomography (MDCT). Using examples from our institutional experience, we shall illustrate important diagnostic features to indicate the underlying lung disease. Understanding the varied range of conditions is important for accurate diagnosis and facilitation of patient management

  17. Tracheo-oesophageal fistula diagnosed with multidetector computed tomography.

    LENUS (Irish Health Repository)

    Hodnett, Pa

    2009-04-01

    This case highlights important issues in investigation of patients with suspected tracheo-oesophageal fistula including the value of multidetector computed tomography, the importance of thorough imaging evaluation when high clinical suspicion of tracheo-oesophageal fistula exists and the value of close interaction between radiologists and intensive care physicians in the investigation of these patients.

  18. Respiratory-Gated Helical Computed Tomography of Lung: Reproducibility of Small Volumes in an Ex Vivo Model

    International Nuclear Information System (INIS)

    Biederer, Juergen; Dinkel, Julien; Bolte, Hendrik; Welzel, Thomas; Hoffmann, Beata M.Sc.; Thierfelder, Carsten; Mende, Ulrich; Debus, Juergen; Heller, Martin; Kauczor, Hans-Ulrich

    2007-01-01

    Purpose: Motion-adapted radiotherapy with gated irradiation or tracking of tumor positions requires dedicated imaging techniques such as four-dimensional (4D) helical computed tomography (CT) for patient selection and treatment planning. The objective was to evaluate the reproducibility of spatial information for small objects on respiratory-gated 4D helical CT using computer-assisted volumetry of lung nodules in a ventilated ex vivo system. Methods and Materials: Five porcine lungs were inflated inside a chest phantom and prepared with 55 artificial nodules (mean diameter, 8.4 mm ± 1.8). The lungs were respirated by a flexible diaphragm and scanned with 40-row detector CT (collimation, 24 x 1.2 mm; pitch, 0.1; rotation time, 1 s; slice thickness, 1.5 mm; increment, 0.8 mm). The 4D-CT scans acquired during respiration (eight per minute) and reconstructed at 0-100% inspiration and equivalent static scans were scored for motion-related artifacts (0 or absent to 3 or relevant). The reproducibility of nodule volumetry (three readers) was assessed using the variation coefficient (VC). Results: The mean volumes from the static and dynamic inspiratory scans were equal (364.9 and 360.8 mm 3 , respectively, p = 0.24). The static and dynamic end-expiratory volumes were slightly greater (371.9 and 369.7 mm 3 , respectively, p = 0.019). The VC for volumetry (static) was 3.1%, with no significant difference between 20 apical and 20 caudal nodules (2.6% and 3.5%, p = 0.25). In dynamic scans, the VC was greater (3.9%, p = 0.004; apical and caudal, 2.6% and 4.9%; p = 0.004), with a significant difference between static and dynamic in the 20 caudal nodules (3.5% and 4.9%, p = 0.015). This was consistent with greater motion-related artifacts and image noise at the diaphragm (p <0.05). The VC for interobserver variability was 0.6%. Conclusion: Residual motion-related artifacts had only minimal influence on volumetry of small solid lesions. This indicates a high reproducibility of

  19. Four-dimensional measurement of intrafractional respiratory motion of pancreatic tumors using a 256 multi-slice CT scanner

    International Nuclear Information System (INIS)

    Mori, Shinichiro; Hara, Ryusuke; Yanagi, Takeshi; Sharp, Gregory C.; Kumagai, Motoki; Asakura, Hiroshi; Kishimoto, Riwa; Yamada, Shigeru; Kandatsu, Susumu; Kamada, Tadashi

    2009-01-01

    Purpose: To quantify pancreas and pancreatic tumor movement due to respiratory motion using volumetric cine CT images. Materials and methods: Six patients with pancreatic tumors were scanned in cine mode with a 256 multi-slice CT scanner under free breathing conditions. Gross tumor volume (GTV) and pancreas were manually contoured on the CT data set by a radiation oncologist. Intrafractional respiratory movement of the GTV and pancreas was calculated, and the results were compared between the respiratory ungated and gated phases, which is a 30% duty cycle around exhalation. Results: Respiratory-induced organ motion was observed mainly in the anterior abdominal side than the posterior side. Average GTV displacement (ungated/gated phases) was 0.7 mm/0.2 mm in both the left and right directions, and 2.5 mm/0.9 mm in the anterior, 0.1 mm/0 mm in the posterior, and 8.9 mm/2.6 mm in the inferior directions. Average pancreas center of mass displacement relative to that at peak exhalation was mainly in the inferior direction, at 9.6 mm in the ungated phase and 2.3 mm in the gated phase. Conclusions: By allowing accurate determination of the margin, quantitative analysis of tumor and pancreas displacement provides useful information in treatment planning in all radiation approaches for pancreatic tumors.

  20. Relationship between noise, dose, and pitch in cardiac multi-detector row CT.

    Science.gov (United States)

    Primak, Andrew N; McCollough, Cynthia H; Bruesewitz, Michael R; Zhang, Jie; Fletcher, Joel G

    2006-01-01

    In spiral computed tomography (CT), dose is always inversely proportional to pitch. However, the relationship between noise and pitch (and hence noise and dose) depends on the scanner type (single vs multi-detector row) and reconstruction mode (cardiac vs noncardiac). In single detector row spiral CT, noise is independent of pitch. Conversely, in noncardiac multi-detector row CT, noise depends on pitch because the spiral interpolation algorithm makes use of redundant data from different detector rows to decrease noise for pitch values less than 1 (and increase noise for pitch values > 1). However, in cardiac spiral CT, redundant data cannot be used because such data averaging would degrade the temporal resolution. Therefore, the behavior of noise versus pitch returns to the single detector row paradigm, with noise being independent of pitch. Consequently, since faster rotation times require lower pitch values in cardiac multi-detector row CT, dose is increased without a commensurate decrease in noise. Thus, the use of faster rotation times will improve temporal resolution, not alter noise, and increase dose. For a particular application, the higher dose resulting from faster rotation speeds should be justified by the clinical benefits of the improved temporal resolution. RSNA, 2006

  1. Multidetector-row CT: economics and workflow

    International Nuclear Information System (INIS)

    Pottala, K.M.; Kalra, M.K.; Saini, S.; Ouellette, K.; Sahani, D.; Thrall, J.H.

    2005-01-01

    With rapid evolution of multidetector-row CT (MDCT) technology and applications, several factors such ad technology upgrade and turf battles for sharing cost and profitability affect MDCT workflow and economics. MDCT workflow optimization can enhance productivity and reduce unit costs as well as increase profitability, in spite of decrease in reimbursement rates. Strategies for workflow management include standardization, automation, and constant assessment of various steps involved in MDCT operations. In this review article, we describe issues related to MDCT economics and workflow. (orig.)

  2. Role of multidetector computed tomography (MDCT) in diagnosis of ...

    African Journals Online (AJOL)

    Aim of the work: To assess the role of multidetector computed tomographic imaging in the diagnosis of secondary intussusception with pathological leading points in children. Materials and methods: This study is a retrospective study including 12 children referred to the radiodiagnosis department at Alexandria University ...

  3. Multidetector CT of blunt traumatic venous injuries in the chest, abdomen, and pelvis.

    Science.gov (United States)

    Holly, Brian P; Steenburg, Scott D

    2011-01-01

    Venous injuries as a result of blunt trauma are rare. Even though current protocols for multidetector computed tomography (CT) of patients with trauma are designed to evaluate primarily the solid organs and arteries, blunt venous injuries may nevertheless be identified, or at least suspected, on the basis of the multidetector CT findings. Venous injuries are associated with high morbidity and mortality rates. Diagnosis of a possible venous injury is crucial because the physical findings of a venous injury are nonspecific and may be absent. This article aims to make the radiologist aware of various venous injuries caused by blunt trauma and to provide helpful hints to aid in the identification of venous injuries. Multidetector CT technology, in combination with interactive manipulation of the raw dataset, can be useful in the creation of multiplanar reconstructed images and in the identification of a venous injury caused by blunt trauma. Familiarity with direct and indirect signs of venous injuries, as well as with examples of blunt traumatic venous injuries in the chest, abdomen, and pelvis, will help in the diagnosis of these injuries.

  4. Weighted expectation maximization reconstruction algorithms with application to gated megavoltage tomography

    International Nuclear Information System (INIS)

    Zhang Jin; Shi Daxin; Anastasio, Mark A; Sillanpaa, Jussi; Chang Jenghwa

    2005-01-01

    We propose and investigate weighted expectation maximization (EM) algorithms for image reconstruction in x-ray tomography. The development of the algorithms is motivated by the respiratory-gated megavoltage tomography problem, in which the acquired asymmetric cone-beam projections are limited in number and unevenly sampled over view angle. In these cases, images reconstructed by use of the conventional EM algorithm can contain ring- and streak-like artefacts that are attributable to a combination of data inconsistencies and truncation of the projection data. By use of computer-simulated and clinical gated fan-beam megavoltage projection data, we demonstrate that the proposed weighted EM algorithms effectively mitigate such image artefacts. (note)

  5. CACTUS - a multidetector set-up at the Oslo Cyclotron

    International Nuclear Information System (INIS)

    Guttormsen, M.; Bjerke, B.; Messelt, S.; Olsen, E.A.; Ramsoey, T.; Rekstad, J.; Tveter, T.S.; Wikne, J.C.; Kownacki, J.

    1989-06-01

    The design and construction of the multidetector system CACTUS is discussed, and its operation in the context of the Oslo Cyclotron is described. The multidetector system has been initiated to meet the requirements at the Oslo Cyclotron Laboratory in the experimental work on nuclear structure at high intrinsic excitation energy. The laboratory has developed a promising technique based on measuring γ-decay after single nucleon transfer reactions with the use of pγ coincidences. However, a proper interpretation of the experimental results has often been difficult due to low counting rates. One of the most important aims for the new experimental set-up has been to obtain pγ as well as pγγ coincidence spectra with high statistics. The CACTUS detector system which is mounted on the 90 o beam line of the cyclotron, consists of 28 NaI and 2 Ge detectors in combination with 8 Si particle telescopes

  6. Multidetector CT for congenital heart patients: what a paediatric radiologist should know

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Jean-Francois; Rohnean, Adela; Sigal-Cinqualbre, Anne [Radiology Unit, Marie Lannelongue Hospital, Plessis-Robinson (France)

    2010-06-15

    Multidetector CT (MDCT) is increasingly used for imaging congenital heart disease (CHD) patients in addition to echocardiography, due to its ability to provide high quality three-dimensional images, giving a comprehensive evaluation of complex heart malformations. Using 4-slice or 16-slice CT, diagnostic information in CHD patients is limited to extra-cardiac anatomy, mainly the pulmonary arteries, aorta and venous connections. Due to high heart rates in babies however, coronary evaluation and intra-cardiac analysis were not reliable with the first generations of MDCT. Larger detector size with 64-slice CT and faster acquisition time, up to 75 ms for one slice, has progressively improved coronary and intra-cardiac visualization. Because radiation dose is the main concern, especially in children, every attempt to minimize dose whilst preserving image quality is important: the ALARA concept should always be applied in this population. The 80 kVp setting is now well accepted as a standard for more and more radiological teams involved in CT of children. Different acquisition strategies are now possible for childhood coronary imaging, using retrospective or even prospective gating. Using the latest technology, sub-mSv acquisitions are now attainable for scanning a whole thorax, providing a complete analysis of any 3-D cardiac malformation, including coronary artery course visualisation. This review will describe how technological developments have improved image quality with continuous reduction of radiation dose. (orig.)

  7. Respiration Gates Sensory Input Responses in the Mitral Cell Layer of the Olfactory Bulb

    Science.gov (United States)

    Short, Shaina M.; Morse, Thomas M.; McTavish, Thomas S.; Shepherd, Gordon M.; Verhagen, Justus V.

    2016-01-01

    Respiration plays an essential role in odor processing. Even in the absence of odors, oscillating excitatory and inhibitory activity in the olfactory bulb synchronizes with respiration, commonly resulting in a burst of action potentials in mammalian mitral/tufted cells (MTCs) during the transition from inhalation to exhalation. This excitation is followed by inhibition that quiets MTC activity in both the glomerular and granule cell layers. Odor processing is hypothesized to be modulated by and may even rely on respiration-mediated activity, yet exactly how respiration influences sensory processing by MTCs is still not well understood. By using optogenetics to stimulate discrete sensory inputs in vivo, it was possible to temporally vary the stimulus to occur at unique phases of each respiration. Single unit recordings obtained from the mitral cell layer were used to map spatiotemporal patterns of glomerular evoked responses that were unique to stimulations occurring during periods of inhalation or exhalation. Sensory evoked activity in MTCs was gated to periods outside phasic respiratory mediated firing, causing net shifts in MTC activity across the cycle. In contrast, odor evoked inhibitory responses appear to be permitted throughout the respiratory cycle. Computational models were used to further explore mechanisms of inhibition that can be activated by respiratory activity and influence MTC responses. In silico results indicate that both periglomerular and granule cell inhibition can be activated by respiration to internally gate sensory responses in the olfactory bulb. Both the respiration rate and strength of lateral connectivity influenced inhibitory mechanisms that gate sensory evoked responses. PMID:28005923

  8. Highly-accelerated self-gated free-breathing 3D cardiac cine MRI: validation in assessment of left ventricular function.

    Science.gov (United States)

    Liu, Jing; Feng, Li; Shen, Hsin-Wei; Zhu, Chengcheng; Wang, Yan; Mukai, Kanae; Brooks, Gabriel C; Ordovas, Karen; Saloner, David

    2017-08-01

    This work presents a highly-accelerated, self-gated, free-breathing 3D cardiac cine MRI method for cardiac function assessment. A golden-ratio profile based variable-density, pseudo-random, Cartesian undersampling scheme was implemented for continuous 3D data acquisition. Respiratory self-gating was achieved by deriving motion signal from the acquired MRI data. A multi-coil compressed sensing technique was employed to reconstruct 4D images (3D+time). 3D cardiac cine imaging with self-gating was compared to bellows gating and the clinical standard breath-held 2D cine imaging for evaluation of self-gating accuracy, image quality, and cardiac function in eight volunteers. Reproducibility of 3D imaging was assessed. Self-gated 3D imaging provided an image quality score of 3.4 ± 0.7 vs 4.0 ± 0 with the 2D method (p = 0.06). It determined left ventricular end-systolic volume as 42.4 ± 11.5 mL, end-diastolic volume as 111.1 ± 24.7 mL, and ejection fraction as 62.0 ± 3.1%, which were comparable to the 2D method, with bias ± 1.96 × SD of -0.8 ± 7.5 mL (p = 0.90), 2.6 ± 3.3 mL (p = 0.84) and 1.4 ± 6.4% (p = 0.45), respectively. The proposed 3D cardiac cine imaging method enables reliable respiratory self-gating performance with good reproducibility, and provides comparable image quality and functional measurements to 2D imaging, suggesting that self-gated, free-breathing 3D cardiac cine MRI framework is promising for improved patient comfort and cardiac MRI scan efficiency.

  9. ROLE OF MULTIDETECTOR CT IN EVALUATION OF NECK LESIONS

    Directory of Open Access Journals (Sweden)

    Reena Mathur

    2016-06-01

    Full Text Available AIMS AND OBJECTIVES To find out the role of multidetector computed tomography in the evaluation of neck lesions with respect to evaluation of the size, location and extent of tumour. Extension of tumour infiltrating into surrounding vascular and visceral structures. To correlate the findings of MD-CT with final diagnosis by biopsy. MATERIAL AND METHODS Data for the study was collected from patients with suspected neck lesions attending Department of Radio-diagnosis, J.L.N. Medical College and Associated Group of Hospitals, Ajmer, Rajasthan. A prospective study was conducted over a period (From 1st March 2014 to 31 Aug. 2015 on patients with clinically suspected neck lesions or patients who were diagnosed to have neck lesion on ultrasound and were referred to CT for further characterisation. The patients presented with symptoms of palpable neck mass and neck pain. Patients were evaluated using multidetector CT. A provisional diagnosis was made after CT scan and these findings were correlated with histopathology/surgical findings as applicable. RESULT In the present study, 97 out of 100 cases were correctly characterised by computed tomography giving an accuracy of 97%. One case of buccal carcinoma was wrongly diagnosed as benign lesion and another case of malignant lymph node was inaccurately diagnosed as benign lymph node, also another case of benign lymph node was inaccurately diagnosed as malignant lymph node. CONCLUSION Multidetector Computed Tomography of the neck has improved the localisation and characterisation of neck lesions. Accurate delineation of disease by CT scan provides a reliable preoperative diagnosis, plan for radiotherapy ports and posttreatment followup. However, histopathology still remains the gold standard as CT is not 100% accurate.

  10. CT paging arteriography with a multidetector-row CT. Advantages in splanchnic arterial imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Seiji [Keio Univ., Tokyo (Japan). School of Medicine

    1999-11-01

    The purpose of this study is to assess the utility of CT paging arteriography with a multidetector-row CT as a replacement for conventional angiography in the evaluation of splanchnic arterial anomalies. Sixty-three patients underwent CT paging arteriography with a multidetector-row CT. In the 56 patients with conventional angiographic correlation, there was only one minor disagreement with CT paging arteriography. In the 7 patients who underwent IVDSA (intra venous digital subtraction angiography), CT paging arteriography defined four hepatic arterial anomalies which could not be depicted by IVDSA. In conclusion, CT paging arteriography provides noninvasive means to identify splanchnic arterial anomalies. (author)

  11. Correcting for respiratory motion in liver PET/MRI: preliminary evaluation of the utility of bellows and navigated hepatobiliary phase imaging

    International Nuclear Information System (INIS)

    Hope, Thomas A.; Verdin, Emily F.; Bergsland, Emily K.; Ohliger, Michael A.; Corvera, Carlos University; Nakakura, Eric K.

    2015-01-01

    The purpose of this study was to evaluate the utility of bellows-based respiratory compensation and navigated hepatobiliary phase imaging to correct for respiratory motion in the setting of dedicated liver PET/MRI. Institutional review board approval and informed consent were obtained. Six patients with metastatic neuroendocrine tumor were imaged using Ga-68 DOTA-TOC PET/MRI. Whole body imaging and a dedicated 15-min liver PET acquisition was performed, in addition to navigated and breath-held hepatobiliary phase (HBP) MRI. Liver PET data was reconstructed three ways: the entire data set (liver PET), gated using respiratory bellows (RC-liver PET), and a non-gated data set reconstructed using the same amount of data used in the RC-liver PET (shortened liver PET). Liver lesions were evaluated using SUV max , SUV peak , SUV mean , and Vol isocontour . Additionally, the displacement of each lesion between the RC-liver PET images and the navigated and breath-held HBP images was calculated. Respiratory compensation resulted in a 43 % increase in SUVs compared to ungated data (liver vs RC-liver PET SUV max 26.0 vs 37.3, p < 0.001) and a 25 % increase compared to a non-gated reconstruction using the same amount of data (RC-liver vs shortened liver PET SUV max 26.0 vs 32.6, p < 0.001). Lesion displacement was minimized using navigated HBP MRI (1.3 ± 1.0 mm) compared to breath-held HBP MRI (23.3 ± 1.0 mm). Respiratory bellows can provide accurate respiratory compensation when imaging liver lesions using PET/MRI, and results in increased SUVs due to a combination of increased image noise and reduced respiratory blurring. Additionally, navigated HBP MRI accurately aligns with respiratory compensated PET data.

  12. Correcting for respiratory motion in liver PET/MRI: preliminary evaluation of the utility of bellows and navigated hepatobiliary phase imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hope, Thomas A. [Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA (United States); Department of Radiology, San Francisco VA Medical Center, San Francisco, CA (United States); Verdin, Emily F. [Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA (United States); Bergsland, Emily K. [Division of Hematology/Oncology, Department of Medicine, University of California, San Francisco, San Francisco, CA (United States); Ohliger, Michael A. [Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA (United States); Department of Radiology, San Francisco General Hospital, San Francisco, CA (United States); Corvera, Carlos University; Nakakura, Eric K. [Division of Surgical Oncology, Department of Surgery, University of California, San Francisco, San Francisco, CA (United States)

    2015-09-18

    The purpose of this study was to evaluate the utility of bellows-based respiratory compensation and navigated hepatobiliary phase imaging to correct for respiratory motion in the setting of dedicated liver PET/MRI. Institutional review board approval and informed consent were obtained. Six patients with metastatic neuroendocrine tumor were imaged using Ga-68 DOTA-TOC PET/MRI. Whole body imaging and a dedicated 15-min liver PET acquisition was performed, in addition to navigated and breath-held hepatobiliary phase (HBP) MRI. Liver PET data was reconstructed three ways: the entire data set (liver PET), gated using respiratory bellows (RC-liver PET), and a non-gated data set reconstructed using the same amount of data used in the RC-liver PET (shortened liver PET). Liver lesions were evaluated using SUV{sub max}, SUV{sub peak}, SUV{sub mean}, and Vol{sub isocontour}. Additionally, the displacement of each lesion between the RC-liver PET images and the navigated and breath-held HBP images was calculated. Respiratory compensation resulted in a 43 % increase in SUVs compared to ungated data (liver vs RC-liver PET SUV{sub max} 26.0 vs 37.3, p < 0.001) and a 25 % increase compared to a non-gated reconstruction using the same amount of data (RC-liver vs shortened liver PET SUV{sub max} 26.0 vs 32.6, p < 0.001). Lesion displacement was minimized using navigated HBP MRI (1.3 ± 1.0 mm) compared to breath-held HBP MRI (23.3 ± 1.0 mm). Respiratory bellows can provide accurate respiratory compensation when imaging liver lesions using PET/MRI, and results in increased SUVs due to a combination of increased image noise and reduced respiratory blurring. Additionally, navigated HBP MRI accurately aligns with respiratory compensated PET data.

  13. Estudio vascular renal por TC multidetector de 64 canales 64-Multidetector row CT for the Renal Vascular Study

    OpenAIRE

    Daniela Stoisa; Fabrizzio E. Galiano; Andrés Quaranta; Roberto L. Villavicencio

    2009-01-01

    Objetivo: Mostrar las diversas variantes anatómicas vasculares tanto arteriales como venosas en el estudio angiográfico renal por tomografìa computada multidetector (TCMD) de 64 canales, dada su implicancia en un eventual planeamiento quirúrgico. Material y métodos: Evaluamos retrospectivamente 26 estudios realizados con tomógrafo Philips Brilliance de 64 canales. Se obtuvieron secuencias sin contraste y postcontraste e.v. en fases arterial y venosa, administrado con bomba inyectora doble cab...

  14. CT portography by multidetector helical CT. Comparison of three rendering models

    International Nuclear Information System (INIS)

    Nakayama, Yoshiharu; Imuta, Masanori; Funama, Yoshinori; Kadota, Masataka; Utsunomiya, Daisuke; Shiraishi, Shinya; Hayashida, Yoshiko; Yamashita, Yasuyuki

    2002-01-01

    The purpose of this study was to assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD). A total of 46 patients with portal hypertension were examined by CT and conventional portography for evaluation of portosystemic collaterals. CT portography was performed by multidetector CT (MD-CT) scanner with a slice thickness of 2.5 mm and table feed of 7.5 mm. Three types of CT portographic models were generated and compared with transarterial portography. Among 46 patients, 48 collaterals were identified on CT transverse images, while 38 collaterals were detected on transarterial portography. Forty-four of 48 collaterals identified on CT transverse images were visualized with the MIP model, while 34 and 29 collaterals were visualized by the VR and SSD methods, respectively. The average CT value for the portal vein and varices was 198 HU with data acquisition of 50 sec after contrast material injection. CT portography by multidetector CT provides excellent images in the visualization of portosystemic collaterals. The images of collaterals produced by MD-CT are superior to those of transarterial portography. Among the three rendering techniques, MIP provides the best visualization of portosystemic collaterals. (author)

  15. CT portography by multidetector helical CT. Comparison of three rendering models

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Yoshiharu; Imuta, Masanori; Funama, Yoshinori; Kadota, Masataka; Utsunomiya, Daisuke; Shiraishi, Shinya; Hayashida, Yoshiko; Yamashita, Yasuyuki [Kumamoto Univ. (Japan). School of Medicine

    2002-12-01

    The purpose of this study was to assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD). A total of 46 patients with portal hypertension were examined by CT and conventional portography for evaluation of portosystemic collaterals. CT portography was performed by multidetector CT (MD-CT) scanner with a slice thickness of 2.5 mm and table feed of 7.5 mm. Three types of CT portographic models were generated and compared with transarterial portography. Among 46 patients, 48 collaterals were identified on CT transverse images, while 38 collaterals were detected on transarterial portography. Forty-four of 48 collaterals identified on CT transverse images were visualized with the MIP model, while 34 and 29 collaterals were visualized by the VR and SSD methods, respectively. The average CT value for the portal vein and varices was 198 HU with data acquisition of 50 sec after contrast material injection. CT portography by multidetector CT provides excellent images in the visualization of portosystemic collaterals. The images of collaterals produced by MD-CT are superior to those of transarterial portography. Among the three rendering techniques, MIP provides the best visualization of portosystemic collaterals. (author)

  16. SU-F-J-151: Evaluation of a Magnetic Resonance Image Gated Radiotherapy System Using a Motion Phantom and Radiochromic Film

    Energy Technology Data Exchange (ETDEWEB)

    Lamb, J; Ginn, J; O’Connell, D; Thomas, D; Agazaryan, N; Cao, M; Yang, Y; Low, D [UCLA, Los Angeles, CA (United States)

    2016-06-15

    Purpose: Magnetic resonance image (MRI) guided radiotherapy enables gating directly on target position for soft-tissue targets in the lung and abdomen. We present a dosimetric evaluation of a commercially-available FDA-approved MRI-guided radiotherapy system’s gating performance using a MRI-compatible respiratory motion phantom and radiochromic film. Methods: The MRI-compatible phantom was capable of one-dimensional motion. The phantom consisted of a target rod containing high-contrast target inserts which moved inside a body structure containing background contrast material. The target rod was equipped with a radiochromic film insert. Treatment plans were generated for a 3 cm diameter spherical target, and delivered to the phantom at rest and in motion with and without gating. Both sinusoidal and actual tumor trajectories (two free-breathing trajectories and one repeated-breath hold) were used. Gamma comparison at 5%/3mm was used to measure fidelity to the static target dose distribution. Results: Without gating, gamma pass rates were 24–47% depending on motion trajectory. Using our clinical standard of repeated breath holds and a gating window of 3 mm with 10% of the target allowed outside the gating boundary, the gamma pass rate was 99.6%. Relaxing the gating window to 5 mm resulted in gamma pass rate of 98.6% with repeated breath holds. For all motion trajectories gated with 3 mm margin and 10% allowed out, gamma pass rates were between 64–100% (mean:87.5%). For a 5 mm margin and 10% allowed out, gamma pass rates were between 57–98% (mean: 82.49%), significantly lower than for 3 mm by paired t-test (p=0.01). Conclusion: We validated the performance of respiratory gating based on real-time cine MRI images with the only FDA-approved MRI-guided radiotherapy system. Our results suggest that repeated breath hold gating should be used when possible for best accuracy. A 3 mm gating margin is statistically significantly more accurate than a 5 mm gating margin.

  17. Study of statistical properties of hybrid statistic in coherent multi-detector compact binary coalescences Search

    OpenAIRE

    Haris, K; Pai, Archana

    2015-01-01

    In this article, we revisit the problem of coherent multi-detector search of gravitational wave from compact binary coalescence with Neutron stars and Black Holes using advanced interferometers like LIGO-Virgo. Based on the loss of optimal multi-detector signal-to-noise ratio (SNR), we construct a hybrid statistic as a best of maximum-likelihood-ratio(MLR) statistic tuned for face-on and face-off binaries. The statistical properties of the hybrid statistic is studied. The performance of this ...

  18. 18F-FDG PET-CT respiratory gating in characterization of pulmonary lesions. Approximation towards clinical indications

    International Nuclear Information System (INIS)

    Garcia Vicente, A.M.; Soriano Castrejon, A.M.; Talavera Rubio, M.P.; Leon Martin, A.A.; Palomar Munoz, A.M.; Pilkington Woll, J.P.; Poblete Garcia, V.M.

    2010-01-01

    The aim of this study was to evaluate the effect of the 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-CT respiratory gating (4D) study in the correct documentation of pulmonary lesions with faint uptake in standard PET-CT. Forty-two pulmonary lesions with a low or no detectable uptake of FDG (standardized uptake value (SUV) max max was determined for each lesion in both studies. For the 4D studies, we selected the SUV max in respiratory period with the highest uptake ('best bin'). We calculated the SUV max percentage difference between 3D and 4D PET-CT (% difference=SUV max 4D-SUV max 3D/SUV max 3D x 100) and the relation of this value with the size and locations of the lesions. In 4D study, any lesion with SUV max ≥2.5 was classified as malignant. We assessed the changes of lesion classification (from benign to malignant) applying the 4D technique. The final diagnosis was obtained by histological assessment or clinical and radiological follow-up longer than 12 months. Forty out of 42 lesions showed an increase of SUV max in the 4D study with respect to 3D. The mean SUV max in the 3D and 4D PET-CT studies were 1.33 (±0.59) and 2.26 (±0.87), respectively. The SUV max percentage difference mean between both techniques was 83.3% (±80.81). The smaller the lesion the greater was the SUV max percentage difference (P<0.05). No differences were observed depending on the location of the lesion. In 40% of cases, there was a change in the final classification of lesions from benign to malignant. In the final diagnosis, 24 lesions were malignant. 4D PET-CT diagnosed correctly the 52% of them. The 4D PET-CT study permitted a better characterization of malignant lung lesions compared with the standard PET-CT, because of its higher sensitivity. 4D PET-CT is a recommendable technique in the early diagnosis of malignant lesions. (author)

  19. Does mean heart dose sufficiently reflect coronary artery exposure in left-sided breast cancer radiotherapy. Influence of respiratory gating

    Energy Technology Data Exchange (ETDEWEB)

    Becker-Schiebe, Martina [Klinikum Braunschweig, Department of Radiotherapy and Radio-Oncology, Braunschweig (Germany); Hannover Medical School, Radiation Oncology, Hannover (Germany); Stockhammer, Maxi; Franz, Heiko [Klinikum Braunschweig, Department of Gynecology and Obstetrics, Braunschweig (Germany); Hoffmann, Wolfgang; Wetzel, Fabian [Klinikum Braunschweig, Department of Radiotherapy and Radio-Oncology, Braunschweig (Germany)

    2016-09-15

    With extensive use of systemic treatment, the issue of cardiac mortality after breast cancer radiation (RT) is still important. The aim of our analysis was to clarify whether the dose to one surrogate parameter (e. g., mean heart dose, as used in most studies) reflects the dose to the other cardiovascular structures especially the left anterior descending artery depending on breathing-adapted RT. A total of 130 patients who underwent adjuvant RT (50.4 Gy plus boost 9-16 Gy) were evaluated. In all, 71 patients were treated with free-breathing and 59 patients using respiratory monitoring (gated RT). Dosimetric associations were calculated. The mean dose to the heart (Dmean heart) was reduced from 2.7 (0.8-5.2) Gy to 2.4 (1.1-4.6) Gy, the Dmean LAD (left anterior descending artery) decreased from 11.1 (1.3-28.6) Gy to 9.3 (2.2-19.9) Gy with gated RT (p = 0.04). A significant relationship was shown for Dmean{sub heart}-Dmean LAD, V25heart-Dmean LAD and Dmax heart-Dmax LAD for gated patients only (p < 0.01). For every 1 Gy increase in Dmean heart, mean LAD doses rose by 3.6 Gy, without gating V25 ≤5 % did not assure a benefit and resulted in Dmean LAD between 1.3 and 28.6 Gy. A significant reduction and association of heart and coronary artery (LAD) doses using inspiratory gating was shown. However, in free-breathing plans commonly measured dose constraints do not allow precise estimation of the dose to the coronary arteries. (orig.) [German] Das Risiko kardialer Spaetfolgen nach Bestrahlung (RT) eines Mammakarzinoms spielt insbesondere auch aufgrund der zunehmenden systemischen Begleittherapien eine wichtige Rolle. Unklar ist, welche koronaren und/oder myokardialen Mechanismen hier entscheidend sind. Der Einfluss der Atemtriggerung und der daraus resultierenden geometrischen Lagevariabilitaet der Risikoorgane auf die Dosisverteilung am Herzen/Koronarien sollte geprueft werden, um zu klaeren, inwieweit die mittlere Herzdosis ein ausreichender Surrogatparameter fuer

  20. Multi-Detector CT Findings of Palpable Chest Wall Masses in Children: A Pictorial Essay

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chan Ho; Kim, Young Tong [Dept. of Radiology, Soonchunhyang University College of Medicine, Cheonan Hospital, Cheonan (Korea, Republic of); Hong, Hyun Sook [Dept. of Radiology, Soonchunhyang University College of Medicine, Bucheon Hospital, Bucheon (Korea, Republic of)

    2013-03-15

    A wide variety of diseases manifest as palpable chest wall masses in children. These include normal variation, congenital anomalies, trauma, infection, axillary lymphadenopathies, soft tissue tumors and bone tumors. Given that most of these diseases are associated with chest wall deformity, diagnosis is difficult by physical examination or ultrasonography alone. However, multi-detector CT with three dimensional reconstruction is useful in the characterization and differential diagnosis of palpable chest wall lesions. In this article, we review the spectrum of palpable chest wall diseases and illustrate their multi-detector CT presentation.

  1. Use of multidetector row CT with volume renderings in right lobe living liver transplantation

    International Nuclear Information System (INIS)

    Ishifuro, Minoru; Akiyama, Yuji; Kushima, Toshio; Horiguchi, Jun; Nakashige, Aya; Tamura, Akihisa; Marukawa, Kazushi; Fukuda, Hiroshi; Ono, Chiaki; Ito, Katsuhide

    2002-01-01

    Multidetector row CT is a feasible diagnostic tool in pre- and postoperative liver partial transplantation. We can assess vascular anatomy and liver parenchyma as well as volumetry, which provide useful information for both donor selection and surgical planning. Disorders of the vascular and biliary systems are carefully observed in recipients. In addition, we evaluate liver regeneration of both the donor and the recipient by serial volumetry. We present how multidetector row CT with state-of-the-art three-dimensional volume renderings may be used in right lobe liver transplantation. (orig.)

  2. Focal Stenosis in Right Upper Lobe Bronchus in a Recurrently Wheezing Child Sequentially Studied by Multidetector-row Spiral Computed Tomography and Scintigraphy

    Directory of Open Access Journals (Sweden)

    I-Chen Chen

    2009-12-01

    Full Text Available Lower respiratory tract infections associated with wheezing are not uncommon in infants and young children. Among the wheezing-associated disorders, allergic etiologies are more commonly encountered than anatomic anomalies. We present a 3-year-old girl with a sudden attack of asthmatic symptoms including dyspnea, cyanosis and diffuse wheezing. Based on a history of choking, and atelectasis in the right upper lobe detected by chest films, flexible tracheobronchoscopy was arranged and incidentally detected a stenotic orifice in the right upper lobe bronchus. Multidetector-row spiral computed tomography and pulmonary scintigraphy subsequently also disclosed the focal stenosis. She suffered from recurrent wheezing, pneumonia and lung atelectasis during 1 year of follow-up. We emphasize the diagnosis, clinical course and management of focal stenosis in the right upper lobe bronchus.

  3. Assessment of hepatic arterial variation using multidetector helical CT-angiography

    International Nuclear Information System (INIS)

    Lee, Dong Hoon; Lee, Jun Woo; Jun, Woong Bae; Lee, Suk Hong

    2001-01-01

    To evaluate the anatomy of the hepatic artery and normal variants using oblique thick-slab maximal intensity projection (MIP) 3-D CT angiography and multidetector helical CT technology. In 70 patients, axial three-phase CT together with multidetector helical CT and a nonionic contrast agent was used to evaluate liver disease. During the early arterial phase, the parameters were as follow: slice thickness, 2.5 mm; table speed, 15 mm/rotation, pitch, 6; contrast material, 4 ml/sec; total 120 ml. Using the MIP technique and an Advantage window voxtal 3.03 system (GE), the images obtained were reconstructed as 3D angiograms. In each case, the arterial anatomy and its variants were recorded. A typical anatomy was found in 53 cases (75.7%). Common variants were a left hepatic artery arising from the left gastric artery(8 cases, 11.4 %) and a right hepatic artery arising from the superior mesenteric artery(3 cases, 4.3%). Other variant cases were right hepatic artery arising from the gastroduodenal artery(2 cases, 2.9%), a proper hepatic artery arising from the left gastric artery (1 case, 1.4%), a hepatomesenteric trunk (1 case), a hepatogastric/splenomesenteric trunk(1 case), and a celiomesenteric trunk (1 case). 3-D hepatic angiography using multidetector helical CT technology is non-invasive and as accurate as conventional angiography for the evaluation of hepatic arterial anatomy. It is thus considered that 3-D CT angiography is very helpful for the evaluation of hepatic arterial anatomy prior to liver surgery such as transplantation or the treatment of hepatocellular carinoma

  4. Dual respiratory and cardiac motion estimation in PET imaging: Methods design and quantitative evaluation.

    Science.gov (United States)

    Feng, Tao; Wang, Jizhe; Tsui, Benjamin M W

    2018-04-01

    The goal of this study was to develop and evaluate four post-reconstruction respiratory and cardiac (R&C) motion vector field (MVF) estimation methods for cardiac 4D PET data. In Method 1, the dual R&C motions were estimated directly from the dual R&C gated images. In Method 2, respiratory motion (RM) and cardiac motion (CM) were separately estimated from the respiratory gated only and cardiac gated only images. The effects of RM on CM estimation were modeled in Method 3 by applying an image-based RM correction on the cardiac gated images before CM estimation, the effects of CM on RM estimation were neglected. Method 4 iteratively models the mutual effects of RM and CM during dual R&C motion estimations. Realistic simulation data were generated for quantitative evaluation of four methods. Almost noise-free PET projection data were generated from the 4D XCAT phantom with realistic R&C MVF using Monte Carlo simulation. Poisson noise was added to the scaled projection data to generate additional datasets of two more different noise levels. All the projection data were reconstructed using a 4D image reconstruction method to obtain dual R&C gated images. The four dual R&C MVF estimation methods were applied to the dual R&C gated images and the accuracy of motion estimation was quantitatively evaluated using the root mean square error (RMSE) of the estimated MVFs. Results show that among the four estimation methods, Methods 2 performed the worst for noise-free case while Method 1 performed the worst for noisy cases in terms of quantitative accuracy of the estimated MVF. Methods 4 and 3 showed comparable results and achieved RMSE lower by up to 35% than that in Method 1 for noisy cases. In conclusion, we have developed and evaluated 4 different post-reconstruction R&C MVF estimation methods for use in 4D PET imaging. Comparison of the performance of four methods on simulated data indicates separate R&C estimation with modeling of RM before CM estimation (Method 3) to be

  5. Physiologically gated microbeam radiation using a field emission x-ray source array

    Energy Technology Data Exchange (ETDEWEB)

    Chtcheprov, Pavel, E-mail: PavelC@unc.edu, E-mail: zhou@email.unc.edu [Department of Biomedical Engineering, University of North Carolina, 152 MacNider Hall, Campus Box 7575, Chapel Hill, North Carolina 27599 (United States); Burk, Laurel; Inscoe, Christina; Ger, Rachel; Hadsell, Michael; Lu, Jianping [Department of Physics and Astronomy, University of North Carolina, Phillips Hall, CB #3255, 120 East Cameron Avenue, Chapel Hill, North Carolina 27599 (United States); Yuan, Hong [Department of Radiology, University of North Carolina, 2006 Old Clinic, CB #7510, Chapel Hill, North Carolina 27599 (United States); Zhang, Lei [Department of Applied Physical Sciences, University of North Carolina, Chapman Hall, CB#3216, Chapel Hill, North Carolina 27599 (United States); Chang, Sha [Department of Radiation Oncology, University of North Carolina, 101 Manning Drive, Chapel Hill, North Carolina 27514 and UNC Lineberger Comprehensive Cancer Center, University of North Carolina, 101 Manning Drive, Chapel Hill, North Carolina 27514 (United States); Zhou, Otto, E-mail: PavelC@unc.edu, E-mail: zhou@email.unc.edu [Department of Physics and Astronomy, University of North Carolina, Phillips Hall, CB #3255, 120 East Cameron Avenue, Chapel Hill, North Carolina 27599 and UNC Lineberger Comprehensive Cancer Center, University of North Carolina, 101 Manning Drive, Chapel Hill, North Carolina 27514 (United States)

    2014-08-15

    Purpose: Microbeam radiation therapy (MRT) uses narrow planes of high dose radiation beams to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000 Gy of peak entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during treatment can lead to significant movement of microbeam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), which reduces the effectiveness of MRT. Recently, the authors have demonstrated the feasibility of generating microbeam radiation for small animal treatment using a carbon nanotube (CNT) x-ray source array. The purpose of this study is to incorporate physiological gating to the CNT microbeam irradiator to minimize motion-induced microbeam blurring. Methods: The CNT field emission x-ray source array with a narrow line focal track was operated at 160 kVp. The x-ray radiation was collimated to a single 280 μm wide microbeam at entrance. The microbeam beam pattern was recorded using EBT2 Gafchromic{sup ©} films. For the feasibility study, a strip of EBT2 film was attached to an oscillating mechanical phantom mimicking mouse chest respiratory motion. The servo arm was put against a pressure sensor to monitor the motion. The film was irradiated with three microbeams under gated and nongated conditions and the full width at half maximums and PVDRs were compared. An in vivo study was also performed with adult male athymic mice. The liver was chosen as the target organ for proof of concept due to its large motion during respiration compared to other organs. The mouse was immobilized in a specialized mouse bed and anesthetized using isoflurane. A pressure sensor was attached to a mouse's chest to monitor its respiration. The output signal triggered the electron extraction voltage of the field emission source such that x-ray was generated only

  6. CHICSI - a proposal for a multi-detector ΔE-E particle telescope

    International Nuclear Information System (INIS)

    Guttormsen, M.

    1992-01-01

    The aim of the CHICSI project is to build a silicon ΔE-E telescope system for the measurement of charged ejectiles produced in violent heavy ion collisions. Of particular interest is the detection of intermediate mass fragments in order to investigate the behavior of nuclear matter under extreme conditions. The report is a first attempt to determine the design parameters of the multidetector system CHICSI. The detector is intended to be used for experiments at the CELSIUS storage ring. Thus, the operation in a storage ring environment requires special attention to the ultra high vacuum condition and target arrangements. The multidetector system will be operated in conjunction with other detector systems as the slow heavy ion recoil detector. 11 refs., 9 figs., 3 tabs

  7. SU-G-JeP3-13: Use of Volumetric Indices to Study the Viability of Respiratory Gating in Conjunction with Abdominal Compression in the Management of Non-Small Cell Lung Cancer Tumors Using Stereotactic Body Radiation Therapy Under the Conditions of Controlled Breathing

    Energy Technology Data Exchange (ETDEWEB)

    Malhotra, H; Gomez, J [Roswell Park Cancer Institute, Buffalo, NY (United States)

    2016-06-15

    Purpose: AAPM TG-76 report advises lung patients experiencing tumor motion >5mm to use some form of motion management with even smaller limit for complex/special procedures like SBRT. Generally, either respiratory gating or abdominal compression is used for motion management. In this retrospective study, we are using an innovative index, Volumetric Indices (VI) = (GTVnn AND GTV{sub 50+}Xmm)/(GTVnn) to quantify how much of the tumor remains within 1, 2, and 3mm margins throughout the breathing cycle using GTV{sub 50+}Xmm margin on GTV{sub 50}[nn=0,10,20,…90]. Using appropriate limits, VI can provide tumor motion information and to check if RPM gates could have been used in conjunction with abdominal compression to better manage tumor motion. Methods: 64 SBRT patients with a total of 67 lung tumors were studied. 4DCT scans were taken, fully capturing tumor motion throughout the 10 phases of the breathing cycle. For each phase, Gross Tumor Volume (GTV) was segmented and appropriates structures were defined to determine VI values. For the 2mm margin, VI values less than 0.95 for peripheral lesions and 0.97 for central lesions indicate tumor movement greater than 4mm. VI values for 1mm and 3mm margins were also analyzed signifying tumor motion of 2mm & 6mm, respectively. Results: Of the 64 patients, 35 (55%) had motion greater than 4mm & could have benefited from respiratory gating. For 5/8 (63%) middle lobe lesions, 21/27 (78%) lower lobe lesions, and 10/32 (31%) upper lobe lesions, gating could have resulted in smaller ITV. 32/55 (58%) peripheral lesions and 4/12 (33%) central lesions could have had gating. Average ITV decreased by 1.25cc (11.43%) and average VI increased by 0.11. Conclusion: Out of 64 patients, 55% exhibited motion greater than 4mm even with abdominal compression. Even with abdominalcompression, lung tumors can move >4mm as the degree of pressure which a patient can tolerate, is patient specific.

  8. Added diagnostic value of respiratory-gated 4D 18F-FDG PET/CT in the detection of liver lesions. A multicenter study

    Energy Technology Data Exchange (ETDEWEB)

    Crivellaro, Cinzia; Landoni, Claudio; Guerra, Luca [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); University of Milan-Bicocca, Milan (Italy); De Ponti, Elena; Morzenti, Sabrina [San Gerardo Hospital, Medical Physics, Monza (Italy); Elisei, Federica [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); Picchio, Maria; Bettinardi, Valentino [IRCCS San Raffaele Scientific Institute, Nuclear Medicine, Milan (Italy); Versari, Annibale [Santa Maria Nuova Hospital IRCCS, Nuclear Medicine, Reggio Emilia (Italy); Fioroni, Federica [Santa Maria Nuova Hospital IRCCS, Medical Physics, Reggio Emilia (Italy); Dziuk, Miroslaw; Tkaczewski, Konrad [Military Institute of Medicine, Warsaw (Poland); Ahond-Vionnet, Renee; Nodari, Guillaume [Hopital Pierre Beregovoy, Service de Medecine Nucleaire, Nevers (France); Todde, Sergio [University of Milan-Bicocca, Tecnomed Foundation, Monza (Italy)

    2018-01-15

    The aim of the present study was to evaluate the added diagnostic value of respiratory-gated 4D18F-FDG PET/CT in liver lesion detection and characterization in a European multicenter retrospective study. Fifty-six oncological patients (29 males and 27 females, mean age, 61.2 ± 11.2 years) from five European centers, submitted to standard 3D-PET/CT and liver 4D-PET/CT were retrospectively evaluated. Based on visual analysis, liver PET/CT findings were scored as positive, negative, or equivocal both in 3D and 4D PET/CT. The impact of 4D-PET/CT on the confidence in classifying liver lesions was assessed. PET/CT findings were compared to histology and clinical follow-up as standard reference and diagnostic accuracy was calculated for both techniques. At semi-quantitative analysis, SUVmax was calculated for each detected lesion in 3D and 4D-PET/CT. Overall, 72 liver lesions were considered for the analysis. Based on visual analysis in 3D-PET/CT, 32/72 (44.4%) lesions were considered positive, 21/72 (29.2%) negative, and 19/72 (26.4%) equivocal, while in 4D-PET/CT 48/72 (66.7%) lesions were defined positive, 23/72 (31.9%) negative, and 1/72 (1.4%) equivocal. 4D-PET/CT findings increased the confidence in lesion definition in 37/72 lesions (51.4%). Considering 3D equivocal lesions as positive, sensitivity, specificity, and accuracy were 88.9, 70.0, and 83.1%, respectively, while the same figures were 67.7, 90.0, and 73.8% if 3D equivocal findings were included as negative. 4D-PET/CT sensitivity, specificity, and accuracy were 97.8, 90.0, and 95.4%, respectively, considering equivocal lesions as positive and 95.6, 90.0, and 93.8% considering equivocal lesions as negative. The SUVmax of the liver lesions in 4D-PET (mean ± SD, 6.9 ± 3.2) was significantly higher (p < 0.001) than SUVmax in 3D-PET (mean ± SD, 5.2 ± 2.3). Respiratory-gated PET/CT technique is a valuable clinical tool in diagnosing liver lesions, reducing 3D undetermined findings, improving diagnostic

  9. Evaluating FDG uptake changes between pre and post therapy respiratory gated PET scans

    International Nuclear Information System (INIS)

    Aristophanous, Michalis; Yong, Yue; Yap, Jeffrey T.; Killoran, Joseph H.; Allen, Aaron M.; Berbeco, Ross I.; Chen, Aileen B.

    2012-01-01

    Purpose: Whole body (3D) and respiratory gated (4D) FDG-PET/CT scans performed pre-radiotherapy (pre-RT) and post-radiotherapy (post-RT) were analyzed to investigate the impact of 4D PET in evaluating 18F-fluorodeoxyglucose (FDG) uptake changes due to therapy, relative to traditional 3D PET. Methods and materials: 3D and 4D sequential FDG-PET/CT scans were acquired pre-RT and approximately one month post-RT for patients with non-small cell lung cancer (NSCLC). The lesions of high uptake targeted with radiotherapy were identified on the pre-RT scan of each patient. Each lesion on the 3D and each of the five phases of the 4D scan were analyzed using a region of interest (ROI). For each patient the ROIs of the pre-RT scans were used to locate the areas of initial FDG uptake on the post-RT scans following rigid registration. Post-RT ROIs were drawn and the FDG uptake was compared with that of the pre-RT scans. Results: Sixteen distinct lesions from 12 patients were identified and analyzed. Standardized uptake value (SUV) maxima were significantly higher (p-value <0.005) for the lesions as measured on the 4D compared to 3D PET. Comparison of serial pre and post-RT scans showed a mean 62% decrease in SUV with the 3D PET scan (range 36–89%), and a 67% decrease with the 4D PET scan (range 30–89%). The mean absolute difference in SUV change on 3D versus 4D scans was 4.9%, with a range 0–15% (p-value = 0.07). Conclusions: Signal recovery with 4D PET results in higher SUVs when compared to standard 3D PET. Consequently, differences in the evaluation of SUV changes between pre and post-RT plans were observed. Such difference can have a significant impact in PET-based response assessment.

  10. Multidetector CT of the colon

    International Nuclear Information System (INIS)

    Luboldt, W.; Hoepffner, N.; Holzer, K.

    2003-01-01

    Multidetector technology, enabling faster imaging, higher spatial resolution and reduction in radiation dose, increases the role of CT in colonic diagnostic. The higher spatial resolution in the z-direction also changes the way to analyze the images. Instead of reading axial sections, now the colon can be systematically assessed in 3D by scrolling through multiplanar reconstructions or in CT colonography by virtual endoscopy. With ongoing improvements in computer-aided diagnosis CT colonography becomes an alternative to fiberoptic colonocopy for screening (http://www.multiorganscreening.org). In this article we propose a CT examination protocol for the colon, describe the typical imaging findings of different colonic diseases, and summarize the current status of CT colonography. (orig.)

  11. Right heart on multidetector CT

    Science.gov (United States)

    Gopalan, D

    2011-01-01

    Right ventricular function plays an integral role in the pathogenesis and outcome of many cardiovascular diseases. Imaging the right ventricle has long been a challenge because of its complex geometry. In recent years there has been a tremendous expansion in multidetector row CT (MDCT) and its cardiac applications. By judicious modification of contrast medium protocol, it is possible to achieve good opacification of the right-sided cardiac chambers, thereby paving the way for exploring the overshadowed right heart. This article will describe the key features of right heart anatomy, review MDCT acquisition techniques, elaborate the various morphological and functional information that can be obtained, and illustrate some important clinical conditions associated with an abnormal right heart. PMID:22723537

  12. SU-E-J-48: Development of An Abdominal Compression Device for Respiratory Correlated Radiation Therapy

    International Nuclear Information System (INIS)

    Kim, T; Kang, S; Kim, D; Suh, T; Kim, S

    2014-01-01

    Purpose: The aim of this study is to develop the abdominal compression device which could control pressure level according to the abdominal respiratory motion and evaluate its feasibility. Methods: In this study, we focused on developing the abdominal compression device which could control pressure level at any point of time so the developed device is possible to use a variety of purpose (gating technique or respiratory training system) while maintaining the merit of the existing commercial device. The compression device (air pad form) was designed to be able to compress the front and side of abdomen and the pressure level of the abdomen is controlled by air flow. Pressure level of abdomen (air flow) was determined using correlation data between external abdominal motion and respiratory volume signal measured by spirometer. In order to verify the feasibility of the device, it was necessary to confirm the correlation between the abdominal respiratory motion and respiratory volume signal and cooperation with respiratory training system also checked. Results: In the previous study, we could find that the correlation coefficient ratio between diaphragm and respiratory volume signal measured by spirometer was 0.95. In this study, we confirmed the correlation between the respiratory volume signal and the external abdominal motion measured by belt-transducer (correlation coefficient ratio was 0.92) and used the correlated respiratory volume data as an abdominal pressure level. It was possible to control the pressure level with negligible time delay and respiratory volume data based guiding waveforms could be properly inserted into the respiratory training system. Conclusion: Through this feasibility study, we confirmed the correlation between the respiratory volume signal and the external abdominal motion. Also initial assessment of the device and its compatibility with the respiratory training system were verified. Further study on application in respiratory gated

  13. Feasibility of deep-inspiration breath-hold PET/CT with short-time acquisition. Detectability for pulmonary lesions compared with respiratory-gated PET/CT

    International Nuclear Information System (INIS)

    Yamashita, Shozo; Yamamoto, Haruki; Hiko, Shigeaki; Horita, Akihiro; Yokoyama, Kunihiko; Onoguchi, Masahisa; Nakajima, Kenichi

    2014-01-01

    Deep-inspiration breath-hold (DIBH) positron emission tomography (PET)/CT with short-time acquisition and respiratory-gated (RG) PET/CT are performed for pulmonary lesions to reduce the respiratory motion artifacts, and to obtain more accurate standardized uptake value (SUV). DIBH PET/CT demonstrates significant advantages in terms of rapid examination, good quality of CT images and low radiation exposure. On the other hand, the image quality of DIBH PET is generally inferior to that of RG PET because of short-time acquisition resulting in poor signal-to-noise ratio. In this study, RG PET has been regarded as a gold standard, and its detectability between DIBH and RG PET studies was compared using each of the most optimal reconstruction parameters. In the phantom study, the most optimal reconstruction parameters for DIBH and RG PET were determined. In the clinical study, 19 cases were examined using each of the most optimal reconstruction parameters. In the phantom study, the most optimal reconstruction parameters for DIBH and RG PET were different. Reconstruction parameters of DIBH PET could be obtained by reducing the number of subsets for those of RG PET in the state of fixing the number of iterations. In the clinical study, high correlation in the maximum SUV was observed between DIBH and RG PET studies. The clinical result was consistent with that of the phantom study surrounded by air since most of the lesions were located in the low pulmonary radioactivity. DIBH PET/CT may be the most practical method which can be the first choice to reduce respiratory motion artifacts if the detectability of DIBH PET is equivalent with that of RG PET. Although DIBH PET may have limitations in suboptimal signal-to-noise ratio, most of the lesions surrounded by low background radioactivity could provide nearly equivalent image quality between DIBH and RG PET studies when each of the most optimal reconstruction parameters was used. (author)

  14. Multidetector computed tomographic pulmonary angiography in patients with a high clinical probability of pulmonary embolism.

    Science.gov (United States)

    Moores, L; Kline, J; Portillo, A K; Resano, S; Vicente, A; Arrieta, P; Corres, J; Tapson, V; Yusen, R D; Jiménez, D

    2016-01-01

    ESSENTIALS: When high probability of pulmonary embolism (PE), sensitivity of computed tomography (CT) is unclear. We investigated the sensitivity of multidetector CT among 134 patients with a high probability of PE. A normal CT alone may not safely exclude PE in patients with a high clinical pretest probability. In patients with no clear alternative diagnosis after CTPA, further testing should be strongly considered. Whether patients with a negative multidetector computed tomographic pulmonary angiography (CTPA) result and a high clinical pretest probability of pulmonary embolism (PE) should be further investigated is controversial. This was a prospective investigation of the sensitivity of multidetector CTPA among patients with a priori clinical assessment of a high probability of PE according to the Wells criteria. Among patients with a negative CTPA result, the diagnosis of PE required at least one of the following conditions: ventilation/perfusion lung scan showing a high probability of PE in a patient with no history of PE, abnormal findings on venous ultrasonography in a patient without previous deep vein thrombosis at that site, or the occurrence of venous thromboembolism (VTE) in a 3-month follow-up period after anticoagulation was withheld because of a negative multidetector CTPA result. We identified 498 patients with a priori clinical assessment of a high probability of PE and a completed CTPA study. CTPA excluded PE in 134 patients; in these patients, the pooled incidence of VTE was 5.2% (seven of 134 patients; 95% confidence interval [CI] 1.5-9.0). Five patients had VTEs that were confirmed by an additional imaging test despite a negative CTPA result (five of 48 patients; 10.4%; 95% CI 1.8-19.1), and two patients had objectively confirmed VTEs that occurred during clinical follow-up of at least 3 months (two of 86 patients; 2.3%; 95% CI 0-5.5). None of the patients had a fatal PE during follow-up. A normal multidetector CTPA result alone may not safely

  15. Registration and Summation of Respiratory-Gated or Breath-Hold PET Images Based on Deformation Estimation of Lung from CT Image

    Directory of Open Access Journals (Sweden)

    Hideaki Haneishi

    2016-01-01

    Full Text Available Lung motion due to respiration causes image degradation in medical imaging, especially in nuclear medicine which requires long acquisition times. We have developed a method for image correction between the respiratory-gated (RG PET images in different respiration phases or breath-hold (BH PET images in an inconsistent respiration phase. In the method, the RG or BH-PET images in different respiration phases are deformed under two criteria: similarity of the image intensity distribution and smoothness of the estimated motion vector field (MVF. However, only these criteria may cause unnatural motion estimation of lung. In this paper, assuming the use of a PET-CT scanner, we add another criterion that is the similarity for the motion direction estimated from inhalation and exhalation CT images. The proposed method was first applied to a numerical phantom XCAT with tumors and then applied to BH-PET image data for seven patients. The resultant tumor contrasts and the estimated motion vector fields were compared with those obtained by our previous method. Through those experiments we confirmed that the proposed method can provide an improved and more stable image quality for both RG and BH-PET images.

  16. Fluoroscopic gating without implanted fiducial markers for lung cancer radiotherapy based on support vector machines

    International Nuclear Information System (INIS)

    Cui Ying; Dy, Jennifer G; Alexander, Brian; Jiang, Steve B

    2008-01-01

    Various problems with the current state-of-the-art techniques for gated radiotherapy have prevented this new treatment modality from being widely implemented in clinical routine. These problems are caused mainly by applying various external respiratory surrogates. There might be large uncertainties in deriving the tumor position from external respiratory surrogates. While tracking implanted fiducial markers has sufficient accuracy, this procedure may not be widely accepted due to the risk of pneumothorax. Previously, we have developed a technique to generate gating signals from fluoroscopic images without implanted fiducial markers using template matching methods (Berbeco et al 2005 Phys. Med. Biol. 50 4481-90, Cui et al 2007b Phys. Med. Biol. 52 741-55). In this note, our main contribution is to provide a totally different new view of the gating problem by recasting it as a classification problem. Then, we solve this classification problem by a well-studied powerful classification method called a support vector machine (SVM). Note that the goal of an automated gating tool is to decide when to turn the beam ON or OFF. We treat ON and OFF as the two classes in our classification problem. We create our labeled training data during the patient setup session by utilizing the reference gating signal, manually determined by a radiation oncologist. We then pre-process these labeled training images and build our SVM prediction model. During treatment delivery, fluoroscopic images are continuously acquired, pre-processed and sent as an input to the SVM. Finally, our SVM model will output the predicted labels as gating signals. We test the proposed technique on five sequences of fluoroscopic images from five lung cancer patients against the reference gating signal as ground truth. We compare the performance of the SVM to our previous template matching method (Cui et al 2007b Phys. Med. Biol. 52 741-55). We find that the SVM is slightly more accurate on average (1-3%) than

  17. Five-dimensional motion compensation for respiratory and cardiac motion with cone-beam CT of the thorax region

    Science.gov (United States)

    Sauppe, Sebastian; Hahn, Andreas; Brehm, Marcus; Paysan, Pascal; Seghers, Dieter; Kachelrieß, Marc

    2016-03-01

    We propose an adapted method of our previously published five-dimensional (5D) motion compensation (MoCo) algorithm1, developed for micro-CT imaging of small animals, to provide for the first time motion artifact-free 5D cone-beam CT (CBCT) images from a conventional flat detector-based CBCT scan of clinical patients. Image quality of retrospectively respiratory- and cardiac-gated volumes from flat detector CBCT scans is deteriorated by severe sparse projection artifacts. These artifacts further complicate motion estimation, as it is required for MoCo image reconstruction. For high quality 5D CBCT images at the same x-ray dose and the same number of projections as todays 3D CBCT we developed a double MoCo approach based on motion vector fields (MVFs) for respiratory and cardiac motion. In a first step our already published four-dimensional (4D) artifact-specific cyclic motion-compensation (acMoCo) approach is applied to compensate for the respiratory patient motion. With this information a cyclic phase-gated deformable heart registration algorithm is applied to the respiratory motion-compensated 4D CBCT data, thus resulting in cardiac MVFs. We apply these MVFs on double-gated images and thereby respiratory and cardiac motion-compensated 5D CBCT images are obtained. Our 5D MoCo approach processing patient data acquired with the TrueBeam 4D CBCT system (Varian Medical Systems). Our double MoCo approach turned out to be very efficient and removed nearly all streak artifacts due to making use of 100% of the projection data for each reconstructed frame. The 5D MoCo patient data show fine details and no motion blurring, even in regions close to the heart where motion is fastest.

  18. MO-FG-BRA-05: Dosimetric and Radiobiological Validation of Respiratory Gating in Conventional and Hypofractionated Radiotherapy of the Lung: Effect of Dose, Dose Rate, Gating Window and Breathing Pattern

    Energy Technology Data Exchange (ETDEWEB)

    Cervino, L; Soultan, D; Pettersson, N; Yock, A; Cornell, M; Aguilera, J; Murphy, J; Advani, S; Moiseenko, V [University of California, San Diego, La Jolla, CA (United States); Gill, B [British Columbia Cancer Agency, Vancouver, BC (Canada)

    2016-06-15

    Purpose: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. Methods: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated. Simultaneous integrated boost (SIB) 6 MV VMAT plans were produced for conventional and hypofractionated radiotherapy, using 30–70 and 100% cycle gating scenarios. Prescribed doses were 200 cGy with SIB to 240 cGy to high uptake volume for conventional, and 800 with SIB to 900 cGy for hypofractionated plans. Dose rates of 600 MU/min (conventional and hypofractionated) and flattening filter free 1400 MU/min (hypofractionated) were used. Ion chamber measurements were performed to verify delivered doses. Vials with A549 cells placed in locations matching ion chamber measurements were irradiated using the same plans to measure clonogenic survival. Differences in survival for the different doses, dose rates, gating windows, and breathing patterns were analyzed. Results: Ion chamber measurements agreed within 3% of the planned dose, for all locations, breathing patterns and gating windows. Cell survival depended on dose alone, and not on gating window, breathing pattern, MU rate, or delivery time. The surviving fraction varied from approximately 40% at 2Gy to 1% for 9 Gy and was within statistical uncertainty relative to that observed for the stationary phantom. Conclusions: Use of gated VMAT in PET-driven SIB radiotherapy was validated using ion chamber measurements and cell survival assays for conventional and hypofractionated radiotherapy.

  19. Robust real-time extraction of respiratory signals from PET list-mode data.

    Science.gov (United States)

    Salomon, Andre; Zhang, Bin; Olivier, Patrick; Goedicke, Andreas

    2018-05-01

    Respiratory motion, which typically cannot simply be suspended during PET image acquisition, affects lesions' detection and quantitative accuracy inside or in close vicinity to the lungs. Some motion compensation techniques address this issue via pre-sorting ("binning") of the acquired PET data into a set of temporal gates, where each gate is assumed to be minimally affected by respiratory motion. Tracking respiratory motion is typically realized using dedicated hardware (e.g. using respiratory belts and digital cameras). Extracting respiratory signalsdirectly from the acquired PET data simplifies the clinical workflow as it avoids to handle additional signal measurement equipment. We introduce a new data-driven method "Combined Local Motion Detection" (CLMD). It uses the Time-of-Flight (TOF) information provided by state-of-the-art PET scanners in order to enable real-time respiratory signal extraction without additional hardware resources. CLMD applies center-of-mass detection in overlapping regions based on simple back-positioned TOF event sets acquired in short time frames. Following a signal filtering and quality-based pre-selection step, the remaining extracted individual position information over time is then combined to generate a global respiratory signal. The method is evaluated using 7 measured FDG studies from single and multiple scan positions of the thorax region, and it is compared to other software-based methods regarding quantitative accuracy and statistical noise stability. Correlation coefficients around 90% between the reference and the extracted signal have been found for those PET scans where motion affected features such as tumors or hot regions were present in the PET field-of-view. For PET scans with a quarter of typically applied radiotracer doses, the CLMD method still provides similar high correlation coefficients which indicates its robustness to noise. Each CLMD processing needed less than 0.4s in total on a standard multi-core CPU

  20. Robust real-time extraction of respiratory signals from PET list-mode data

    Science.gov (United States)

    Salomon, André; Zhang, Bin; Olivier, Patrick; Goedicke, Andreas

    2018-06-01

    Respiratory motion, which typically cannot simply be suspended during PET image acquisition, affects lesions’ detection and quantitative accuracy inside or in close vicinity to the lungs. Some motion compensation techniques address this issue via pre-sorting (‘binning’) of the acquired PET data into a set of temporal gates, where each gate is assumed to be minimally affected by respiratory motion. Tracking respiratory motion is typically realized using dedicated hardware (e.g. using respiratory belts and digital cameras). Extracting respiratory signals directly from the acquired PET data simplifies the clinical workflow as it avoids handling additional signal measurement equipment. We introduce a new data-driven method ‘combined local motion detection’ (CLMD). It uses the time-of-flight (TOF) information provided by state-of-the-art PET scanners in order to enable real-time respiratory signal extraction without additional hardware resources. CLMD applies center-of-mass detection in overlapping regions based on simple back-positioned TOF event sets acquired in short time frames. Following a signal filtering and quality-based pre-selection step, the remaining extracted individual position information over time is then combined to generate a global respiratory signal. The method is evaluated using seven measured FDG studies from single and multiple scan positions of the thorax region, and it is compared to other software-based methods regarding quantitative accuracy and statistical noise stability. Correlation coefficients around 90% between the reference and the extracted signal have been found for those PET scans where motion affected features such as tumors or hot regions were present in the PET field-of-view. For PET scans with a quarter of typically applied radiotracer doses, the CLMD method still provides similar high correlation coefficients which indicates its robustness to noise. Each CLMD processing needed less than 0.4 s in total on a standard

  1. Noninvasive coronary angioscopy using electron beam computed tomography and multidetector computed tomography

    NARCIS (Netherlands)

    van Ooijen, PMA; Nieman, K; de Feyter, PJ; Oudkerk, M

    2002-01-01

    With the advent of noninvasive coronary imaging techniques like multidetector computed tomography and electron beam computed tomography, new representation methods such as intracoronary visualization. have been introduced. We explore the possibilities of these novel visualization techniques and

  2. A statistical method for retrospective cardiac and respiratory motion gating of interventional cardiac x-ray images

    Energy Technology Data Exchange (ETDEWEB)

    Panayiotou, Maria, E-mail: maria.panayiotou@kcl.ac.uk; King, Andrew P.; Housden, R. James; Ma, YingLiang; Rhode, Kawal S. [Division of Imaging Sciences and Biomedical Engineering, King' s College London, London SE1 7EH (United Kingdom); Cooklin, Michael; O' Neill, Mark; Gill, Jaswinder; Rinaldi, C. Aldo [Department of Cardiology, Guy' s and St. Thomas' Hospitals NHS Foundation Trust, London SE1 7EH (United Kingdom)

    2014-07-15

    Purpose: Image-guided cardiac interventions involve the use of fluoroscopic images to guide the insertion and movement of interventional devices. Cardiorespiratory gating can be useful for 3D reconstruction from multiple x-ray views and for reducing misalignments between 3D anatomical models overlaid onto fluoroscopy. Methods: The authors propose a novel and potentially clinically useful retrospective cardiorespiratory gating technique. The principal component analysis (PCA) statistical method is used in combination with other image processing operations to make our proposed masked-PCA technique suitable for cardiorespiratory gating. Unlike many previously proposed techniques, our technique is robust to varying image-content, thus it does not require specific catheters or any other optically opaque structures to be visible. Therefore, it works without any knowledge of catheter geometry. The authors demonstrate the application of our technique for the purposes of retrospective cardiorespiratory gating of normal and very low dose x-ray fluoroscopy images. Results: For normal dose x-ray images, the algorithm was validated using 28 clinical electrophysiology x-ray fluoroscopy sequences (2168 frames), from patients who underwent radiofrequency ablation (RFA) procedures for the treatment of atrial fibrillation and cardiac resynchronization therapy procedures for heart failure. The authors established end-systole, end-expiration, and end-inspiration success rates of 97.0%, 97.9%, and 97.0%, respectively. For very low dose applications, the technique was tested on ten x-ray sequences from the RFA procedures with added noise at signal to noise ratio (SNR) values of√(5)0, √(1)0, √(8), √(6), √(5), √(2), and √(1) to simulate the image quality of increasingly lower dose x-ray images. Even at the low SNR value of √(2), representing a dose reduction of more than 25 times, gating success rates of 89.1%, 88.8%, and 86.8% were established. Conclusions: The proposed

  3. Inhibition of protein kinase A and GIRK channel reverses fentanyl-induced respiratory depression.

    Science.gov (United States)

    Liang, Xiaonan; Yong, Zheng; Su, Ruibin

    2018-06-11

    Opioid-induced respiratory depression is a major obstacle to improving the clinical management of moderate to severe chronic pain. Opioids inhibit neuronal activity via various pathways, including calcium channels, adenylyl cyclase, and potassium channels. Currently, the underlying molecular pathway of opioid-induced respiratory depression is only partially understood. This study aimed to investigate the mechanisms of opioid-induced respiratory depression in vivo by examining the effects of different pharmacological agents on fentanyl-induced respiratory depression. Respiratory parameters were detected using whole body plethysmography in conscious rats. We show that pre-treatment with the protein kinase A (PKA) inhibitor H89 reversed the fentanyl-related effects on respiratory rate, inspiratory time, and expiratory time. Pre-treatment with the G protein-gated inwardly rectifying potassium (GIRK) channel blocker Tertiapin-Q dose-dependently reversed the fentanyl-related effects on respiratory rate and inspiratory time. A phosphodiesterase 4 (PDE4) inhibitor and cyclic adenosine monophosphate (cAMP) analogs did not affect fentanyl-induced respiratory depression. These findings suggest that PKA and GIRK may be involved in fentanyl-induced respiratory depression and could represent useful therapeutic targets for the treatment of fentanyl-induced ventilatory depression. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. 100-nm gate lithography for double-gate transistors

    Science.gov (United States)

    Krasnoperova, Azalia A.; Zhang, Ying; Babich, Inna V.; Treichler, John; Yoon, Jung H.; Guarini, Kathryn; Solomon, Paul M.

    2001-09-01

    The double gate field effect transistor (FET) is an exploratory device that promises certain performance advantages compared to traditional CMOS FETs. It can be scaled down further than the traditional devices because of the greater electrostatic control by the gates on the channel (about twice as short a channel length for the same gate oxide thickness), has steeper sub-threshold slope and about double the current for the same width. This paper presents lithographic results for double gate FET's developed at IBM's T. J. Watson Research Center. The device is built on bonded wafers with top and bottom gates self-aligned to each other. The channel is sandwiched between the top and bottom polysilicon gates and the gate length is defined using DUV lithography. An alternating phase shift mask was used to pattern gates with critical dimensions of 75 nm, 100 nm and 125 nm in photoresist. 50 nm gates in photoresist have also been patterned by 20% over-exposure of nominal 100 nm lines. No trim mask was needed because of a specific way the device was laid out. UV110 photoresist from Shipley on AR-3 antireflective layer were used. Process windows, developed and etched patterns are presented.

  5. Motion-compensated PET image reconstruction with respiratory-matched attenuation correction using two low-dose inhale and exhale CT images

    International Nuclear Information System (INIS)

    Nam, Woo Hyun; Ahn, Il Jun; Ra, Jong Beom; Kim, Kyeong Min; Kim, Byung Il

    2013-01-01

    Positron emission tomography (PET) is widely used for diagnosis and follow up assessment of radiotherapy. However, thoracic and abdominal PET suffers from false staging and incorrect quantification of the radioactive uptake of lesion(s) due to respiratory motion. Furthermore, respiratory motion-induced mismatch between a computed tomography (CT) attenuation map and PET data often leads to significant artifacts in the reconstructed PET image. To solve these problems, we propose a unified framework for respiratory-matched attenuation correction and motion compensation of respiratory-gated PET. For the attenuation correction, the proposed algorithm manipulates a 4D CT image virtually generated from two low-dose inhale and exhale CT images, rather than a real 4D CT image which significantly increases the radiation burden on a patient. It also utilizes CT-driven motion fields for motion compensation. To realize the proposed algorithm, we propose an improved region-based approach for non-rigid registration between body CT images, and we suggest a selection scheme of 3D CT images that are respiratory-matched to each respiratory-gated sinogram. In this work, the proposed algorithm was evaluated qualitatively and quantitatively by using patient datasets including lung and/or liver lesion(s). Experimental results show that the method can provide much clearer organ boundaries and more accurate lesion information than existing algorithms by utilizing two low-dose CT images. (paper)

  6. [Sigmoid endometriosis: a diagnostic dilemma on multidetector CT].

    Science.gov (United States)

    Telegrafo, Michele; Lorusso, Valentina; Rubini, Giuseppe; Rella, Leonarda; Pezzolla, Angela; Stabile Ianora, Amato Antonio; Moschetta, Marco

    2013-01-01

    Intestinal endometriosis represents a common condition that occurs particularly in women of reproductive age. The gastrointestinal tract is the third most common localization of endometriosis, after the ovaries and the peritoneum, and recto-sigmoid tract is involved in 70% of cases. Recto-sigmoid endometriosis has to be differentiated from other diseases of large bowel, especially in patients without a history of endometriosis. We report a case of sigmoid endometriosis which represented a diagnostic dilemma on multidetector computed tomography.

  7. Simultaneous ECG-gated PET imaging of multiple mice

    International Nuclear Information System (INIS)

    Seidel, Jurgen; Bernardo, Marcelino L.; Wong, Karen J.; Xu, Biying; Williams, Mark R.; Kuo, Frank; Jagoda, Elaine M.; Basuli, Falguni; Li, Changhui; Griffiths, Gary L.

    2014-01-01

    Introduction: We describe and illustrate a method for creating ECG-gated PET images of the heart for each of several mice imaged at the same time. The method is intended to increase “throughput” in PET research studies of cardiac dynamics or to obtain information derived from such studies, e.g. tracer concentration in end-diastolic left ventricular blood. Methods: An imaging bed with provisions for warming, anesthetic delivery, etc., was fabricated by 3D printing to allow simultaneous PET imaging of two side-by-side mice. After electrode attachment, tracer injection and placement of the animals in the scanner field of view, ECG signals from each animal were continuously analyzed and independent trigger markers generated whenever an R-wave was detected in each signal. PET image data were acquired in “list” mode and these trigger markers were inserted into this list along with the image data. Since each mouse is in a different spatial location in the FOV, sorting of these data using trigger markers first from one animal and then the other yields two independent and correctly formed ECG-gated image sequences that reflect the dynamical properties of the heart during an “average” cardiac cycle. Results: The described method yields two independent ECG-gated image sequences that exhibit the expected properties in each animal, e.g. variation of the ventricular cavity volumes from maximum to minimum and back during the cardiac cycle in the processed animal with little or no variation in these volumes during the cardiac cycle in the unprocessed animal. Conclusion: ECG-gated image sequences for each of several animals can be created from a single list mode data collection using the described method. In principle, this method can be extended to more than two mice (or other animals) and to other forms of physiological gating, e.g. respiratory gating, when several subjects are imaged at the same time

  8. Prognostic implications of nonobstructive coronary plaques in patients with non-ST-segment elevation myocardial infarction: a multidetector computed tomography study

    DEFF Research Database (Denmark)

    Kristensen, Thomas S; Kofoed, Klaus F; Kühl, Jørgen T

    2011-01-01

    We sought to determine whether the amount of noncalcified plaque (NCP) in nonobstructive coronary lesions as detected by multidetector computed tomography (MDCT) was a predictor of future coronary events.......We sought to determine whether the amount of noncalcified plaque (NCP) in nonobstructive coronary lesions as detected by multidetector computed tomography (MDCT) was a predictor of future coronary events....

  9. Multidetector computed tomography of jaw lesions in children and adolescents

    International Nuclear Information System (INIS)

    Gadodia, A.; Seith, A.; Sharma, R.; Choudhury, A.R.; Bhutia, O.; Gupta, A.

    2010-01-01

    Full text: Jaw lesions in paediatric and adolescent population are uncommon and can arise in odontogenic or non-odontogenic tissues. With the advent of multidetector computed tomography (MDCT), algorithm for imaging jaw lesions has changed dramatically. This pictorial essay describes the imaging appearance of commonly encountered jaw lesions in children and adolescents with emphasis on MDCT findings

  10. Gating-ML: XML-based gating descriptions in flow cytometry.

    Science.gov (United States)

    Spidlen, Josef; Leif, Robert C; Moore, Wayne; Roederer, Mario; Brinkman, Ryan R

    2008-12-01

    The lack of software interoperability with respect to gating due to lack of a standardized mechanism for data exchange has traditionally been a bottleneck, preventing reproducibility of flow cytometry (FCM) data analysis and the usage of multiple analytical tools. To facilitate interoperability among FCM data analysis tools, members of the International Society for the Advancement of Cytometry (ISAC) Data Standards Task Force (DSTF) have developed an XML-based mechanism to formally describe gates (Gating-ML). Gating-ML, an open specification for encoding gating, data transformations and compensation, has been adopted by the ISAC DSTF as a Candidate Recommendation. Gating-ML can facilitate exchange of gating descriptions the same way that FCS facilitated for exchange of raw FCM data. Its adoption will open new collaborative opportunities as well as possibilities for advanced analyses and methods development. The ISAC DSTF is satisfied that the standard addresses the requirements for a gating exchange standard.

  11. Imaging patterns of hepatic steatosis on multidetector CT: Pearls and pitfalls

    Energy Technology Data Exchange (ETDEWEB)

    Kani, K.K., E-mail: khalatbarik@yahoo.com [Department of Radiology, Body Imaging, University of Washington Medical Center, Seattle, WA (United States); Moshiri, M.; Cuevas, C.; Lee, J.H.; Mitsumori, L.M.; Kolokythas, O. [Department of Radiology, Body Imaging, University of Washington Medical Center, Seattle, WA (United States)

    2012-04-15

    Fatty liver disease is an important cause of chronic liver disease in Western countries. The purpose of this article is to describe and illustrate the diagnostic criteria and various morphological patterns of fatty liver disease on multidetector computed tomography (MDCT) with an emphasis on potential limitations and diagnostic pitfalls.

  12. Hypervascular hepatocellular carcinomas: detection with gadoxetate disodium-enhanced MR imaging and multiphasic multidetector CT

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Hiromitsu; Kim, Tonsok; Hori, Masatoshi; Nakaya, Yasuhiro; Tsuboyama, Takahiro; Nakamoto, Atsushi; Tatsumi, Mitsuaki; Tomiyama, Noriyuki [Osaka University Graduate School of Medicine, Department of Radiology, Suita, Osaka (Japan); Imai, Yasuharu [Ikeda Municipal Hospital, Department of Gastroenterology, Ikeda, Osaka (Japan); Nagano, Hiroaki [Osaka University Graduate School of Medicine, Department of Surgery, Suita, Osaka (Japan); Kumano, Seishi; Okada, Masahiro; Murakami, Takamichi [Kinki University School of Medicine, Department of Radiology, Osakasayama, Osaka (Japan); Takamura, Manabu [Ikeda Municipal Hospital, Department of Radiology, Ikeda, Osaka (Japan); Wakasa, Kenichi [Osaka City University Graduate School of Medicine, Department of Diagnostic Pathology, Osaka, Osaka (Japan)

    2012-04-15

    To retrospectively compare the accuracy of detection of hypervascular hepatocellular carcinoma (HCC) by multiphasic multidetector CT and by gadoxetate disodium-enhanced MR imaging. After ethical approval, we analysed a total of 73 hypervascular HCC lesions from 31 patients suspected of having HCC, who underwent both gadoxetate disodium-enhanced MR imaging and multiphasic multidetector CT. Five blinded observers independently reviewed CT images, as well as dynamic MR images alone and combined with hepatobiliary phase MR images. Diagnostic accuracy (Az values), sensitivities and positive predictive values were compared by using the Scheffe post hoc test. The mean Az value for dynamic and hepatobiliary phase MR combined (0.81) or dynamic MR images alone (0.78) was significantly higher than that for CT images (0.67, P < 0.001, 0.005, respectively). The mean sensitivity of the combined MR images (0.67) was significantly higher than that of dynamic MR alone (0.52, P < 0.05) or CT images (0.44, P < 0.05). The mean positive predictive values were 0.96, 0.95 and 0.94, for CT, dynamic MR alone and combined MR images, respectively. Compared with multiphasic multidetector CT, gadoxetate disodium-enhanced MR imaging combining dynamic and hepatobiliary phase images results in significantly improved sensitivity and diagnostic accuracy for detection of hypervascular HCC. (orig.)

  13. Identification of an HV 1 voltage-gated proton channel in insects.

    Science.gov (United States)

    Chaves, Gustavo; Derst, Christian; Franzen, Arne; Mashimo, Yuta; Machida, Ryuichiro; Musset, Boris

    2016-04-01

    The voltage-gated proton channel 1 (HV 1) is an important component of the cellular proton extrusion machinery and is essential for charge compensation during the respiratory burst of phagocytes. HV 1 has been identified in a wide range of eukaryotes throughout the animal kingdom, with the exception of insects. Therefore, it has been proposed that insects do not possess an HV 1 channel. In the present study, we report the existence of an HV 1-type proton channel in insects. We searched insect transcriptome shotgun assembly (TSA) sequence databases and found putative HV 1 orthologues in various polyneopteran insects. To confirm that these putative HV 1 orthologues were functional channels, we studied the HV 1 channel of Nicoletia phytophila (NpHV 1), an insect of the Zygentoma order, in more detail. NpHV 1 comprises 239 amino acids and is 33% identical to the human voltage-gated proton channel 1. Patch clamp measurements in a heterologous expression system showed proton selectivity, as well as pH- and voltage-dependent gating. Interestingly, NpHV 1 shows slightly enhanced pH-dependent gating compared to the human channel. Mutations in the first transmembrane segment at position 66 (Asp66), the presumed selectivity filter, lead to a loss of proton-selective conduction, confirming the importance of this aspartate residue in voltage-gated proton channels. Nucleotide sequence data have been deposited in the GenBank database under accession number KT780722. © 2016 Federation of European Biochemical Societies.

  14. Respiration Induced Heart Motion and Indications of Gated Delivery for Left-Sided Breast Irradiation

    International Nuclear Information System (INIS)

    Qi, X. Sharon; Hu, Angela; Wang Kai; Newman, Francis; Crosby, Marcus; Hu Bin; White, Julia; Li, X. Allen

    2012-01-01

    Purpose: To investigate respiration-induced heart motion for left-sided breast irradiation using a four-dimensional computed tomography (4DCT) technique and to determine novel indications to assess heart motion and identify breast patients who may benefit from a gated treatment. Methods and Materials: Images of 4DCT acquired during free breathing for 20 left-sided breast cancer patients, who underwent whole breast irradiation with or without regional nodal irradiation, were analyzed retrospectively. Dose distributions were reconstructed in the phases of 0%, 20%, and 50%. The intrafractional heart displacement was measured in three selected transverse CT slices using D LAD (the distance from left ascending aorta to a fixed line [connecting middle point of sternum and the body] drawn on each slice) and maximum heart depth (MHD, the distance of the forefront of the heart to the line). Linear regression analysis was used to correlate these indices with mean heart dose and heart dose volume at different breathing phases. Results: Respiration-induced heart displacement resulted in observable variations in dose delivered to the heart. During a normal free-breathing cycle, heart-induced motion D LAD and MHD changed up to 9 and 11 mm respectively, resulting in up to 38% and 39% increases of mean doses and V 25.2 for the heart. MHD and D LAD were positively correlated with mean heart dose and heart dose volume. Respiratory-adapted gated treatment may better spare heart and ipsilateral-lung compared with the conventional non-gated plan in a subset of patients with large D LAD or MHD variations. Conclusion: Proposed indices offer novel assessment of heart displacement based on 4DCT images. MHD and D LAD can be used independently or jointly as selection criteria for respiratory gating procedure before treatment planning. Patients with great intrafractional MHD variations or tumor(s) close to the diaphragm may particularly benefit from the gated treatment.

  15. Respiration Induced Heart Motion and Indications of Gated Delivery for Left-Sided Breast Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Qi, X. Sharon, E-mail: xiangrong.qi@ucdenver.edu [Department of Radiation Oncology, University of Colorado Denver, Aurora, CO (United States); Hu, Angela [Department of Radiation Oncology, University of Colorado Denver, Aurora, CO (United States); Wang Kai [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States); Newman, Francis [Department of Radiation Oncology, University of Colorado Denver, Aurora, CO (United States); Crosby, Marcus; Hu Bin; White, Julia; Li, X. Allen [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States)

    2012-04-01

    Purpose: To investigate respiration-induced heart motion for left-sided breast irradiation using a four-dimensional computed tomography (4DCT) technique and to determine novel indications to assess heart motion and identify breast patients who may benefit from a gated treatment. Methods and Materials: Images of 4DCT acquired during free breathing for 20 left-sided breast cancer patients, who underwent whole breast irradiation with or without regional nodal irradiation, were analyzed retrospectively. Dose distributions were reconstructed in the phases of 0%, 20%, and 50%. The intrafractional heart displacement was measured in three selected transverse CT slices using D{sub LAD} (the distance from left ascending aorta to a fixed line [connecting middle point of sternum and the body] drawn on each slice) and maximum heart depth (MHD, the distance of the forefront of the heart to the line). Linear regression analysis was used to correlate these indices with mean heart dose and heart dose volume at different breathing phases. Results: Respiration-induced heart displacement resulted in observable variations in dose delivered to the heart. During a normal free-breathing cycle, heart-induced motion D{sub LAD} and MHD changed up to 9 and 11 mm respectively, resulting in up to 38% and 39% increases of mean doses and V{sub 25.2} for the heart. MHD and D{sub LAD} were positively correlated with mean heart dose and heart dose volume. Respiratory-adapted gated treatment may better spare heart and ipsilateral-lung compared with the conventional non-gated plan in a subset of patients with large D{sub LAD} or MHD variations. Conclusion: Proposed indices offer novel assessment of heart displacement based on 4DCT images. MHD and D{sub LAD} can be used independently or jointly as selection criteria for respiratory gating procedure before treatment planning. Patients with great intrafractional MHD variations or tumor(s) close to the diaphragm may particularly benefit from the gated

  16. Dataset of calcified plaque condition in the stenotic coronary artery lesion obtained using multidetector computed tomography to indicate the addition of rotational atherectomy during percutaneous coronary intervention

    Directory of Open Access Journals (Sweden)

    Yasushi Akutsu

    2016-06-01

    Full Text Available Our data shows the regional coronary artery calcium scores (lesion CAC on multidetector computed tomography (MDCT and the cross-section imaging on MDCT angiography (CTA in the target lesion of the patients with stable angina pectoris who were scheduled for percutaneous coronary intervention (PCI. CAC and CTA data were measured using a 128-slice scanner (Somatom Definition AS+; Siemens Medical Solutions, Forchheim, Germany before PCI. CAC was measured in a non-contrast-enhanced scan and was quantified using the Calcium Score module of SYNAPSE VINCENT software (Fujifilm Co. Tokyo, Japan and expressed in Agatston units. CTA were then continued with a contrast-enhanced ECG gating to measure the severity of the calcified plaque condition. We present that both CAC and CTA data are used as a benchmark to consider the addition of rotational atherectomy during PCI to severely calcified plaque lesions.

  17. Markerless gating for lung cancer radiotherapy based on machine learning techniques

    International Nuclear Information System (INIS)

    Lin Tong; Li Ruijiang; Tang Xiaoli; Jiang, Steve B; Dy, Jennifer G

    2009-01-01

    In lung cancer radiotherapy, radiation to a mobile target can be delivered by respiratory gating, for which we need to know whether the target is inside or outside a predefined gating window at any time point during the treatment. This can be achieved by tracking one or more fiducial markers implanted inside or near the target, either fluoroscopically or electromagnetically. However, the clinical implementation of marker tracking is limited for lung cancer radiotherapy mainly due to the risk of pneumothorax. Therefore, gating without implanted fiducial markers is a promising clinical direction. We have developed several template-matching methods for fluoroscopic marker-less gating. Recently, we have modeled the gating problem as a binary pattern classification problem, in which principal component analysis (PCA) and support vector machine (SVM) are combined to perform the classification task. Following the same framework, we investigated different combinations of dimensionality reduction techniques (PCA and four nonlinear manifold learning methods) and two machine learning classification methods (artificial neural networks-ANN and SVM). Performance was evaluated on ten fluoroscopic image sequences of nine lung cancer patients. We found that among all combinations of dimensionality reduction techniques and classification methods, PCA combined with either ANN or SVM achieved a better performance than the other nonlinear manifold learning methods. ANN when combined with PCA achieves a better performance than SVM in terms of classification accuracy and recall rate, although the target coverage is similar for the two classification methods. Furthermore, the running time for both ANN and SVM with PCA is within tolerance for real-time applications. Overall, ANN combined with PCA is a better candidate than other combinations we investigated in this work for real-time gated radiotherapy.

  18. Contrast-enhanced ultrasound vs multidetector-computed tomography for detecting liver metastases in colorectal cancer: a prospective, blinded, patient-by-patient analysis

    DEFF Research Database (Denmark)

    Rafaelsen, S R; Jakobsen, A

    2011-01-01

    This study compared the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) and multidetector-computed tomography (MDCT) in the detection of liver metastases in patients with colorectal cancer.......This study compared the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) and multidetector-computed tomography (MDCT) in the detection of liver metastases in patients with colorectal cancer....

  19. Measurement of cardiac ventricular volumes using multidetector row computed tomography: comparison of two- and three-dimensional methods

    International Nuclear Information System (INIS)

    Montaudon, M.; Laffon, E.; Berger, P.; Corneloup, O.; Latrabe, V.; Laurent, F.

    2006-01-01

    This study compared a three-dimensional volumetric threshold-based method to a two-dimensional Simpson's rule based short-axis multiplanar method for measuring right (RV) and left ventricular (LV) volumes, stroke volumes, and ejection fraction using electrocardiography-gated multidetector computed tomography (MDCT) data sets. End-diastolic volume (EDV) and end-systolic volume (ESV) of RV and LV were measured independently and blindly by two observers from contrast-enhanced MDCT images using commercial software in 18 patients. For RV and LV the three-dimensionally calculated EDV and ESV values were smaller than those provided by two-dimensional short axis (10%, 5%, 15% and 26% differences respectively). Agreement between the two methods was found for LV (EDV/ESV: r=0.974/0.910, ICC=0.905/0.890) but not for RV (r=0.882/0.930, ICC=0.663/0.544). Measurement errors were significant only for EDV of LV using the two-dimensional method. Similar reproducibility was found for LV measurements, but the three-dimensional method provided greater reproducibility for RV measurements than the two-dimensional. The threshold value supported three-dimensional method provides reproducible cardiac ventricular volume measurements, comparable to those obtained using the short-axis Simpson based method. (orig.)

  20. Current status of multi-detector row helical CT in imaging of adult ...

    African Journals Online (AJOL)

    Current status of multi-detector row helical CT in imaging of adult acquired pancreatic diseases and assessing surgical neoplastic resectability. ... The presence of inflammation, masses, and vascular invasion was evaluated and interpreted images were obtained during each phase. Results were compared with surgery, ...

  1. Automated quantitative coronary computed tomography correlates of myocardial ischaemia on gated myocardial perfusion SPECT

    International Nuclear Information System (INIS)

    Graaf, Michiel A. de; Boogers, Mark J.; Veltman, Caroline E.; El-Naggar, Heba M.; Bax, Jeroen J.; Delgado, Victoria; Broersen, Alexander; Kitslaar, Pieter H.; Dijkstra, Jouke; Kroft, Lucia J.; Younis, Imad Al; Reiber, Johan H.; Scholte, Arthur J.

    2013-01-01

    Automated software tools have permitted more comprehensive, robust and reproducible quantification of coronary stenosis, plaque burden and plaque location of coronary computed tomography angiography (CTA) data. The association between these quantitative CTA (QCT) parameters and the presence of myocardial ischaemia has not been explored. The aim of the present investigation was to evaluate the association between QCT parameters of coronary artery lesions and the presence of myocardial ischaemia on gated myocardial perfusion single-photon emission CT (SPECT). Included in the study were 40 patients (mean age 58.2 ± 10.9 years, 27 men) with known or suspected coronary artery disease (CAD) who had undergone multidetector row CTA and gated myocardial perfusion SPECT within 6 months. From the CTA datasets, vessel-based and lesion-based visual analyses were performed. Consecutively, lesion-based QCT was performed to assess plaque length, plaque burden, percentage lumen area stenosis and remodelling index. Subsequently, the presence of myocardial ischaemia was assessed using the summed difference score (SDS ≥2) on gated myocardial perfusion SPECT. Myocardial ischaemia was seen in 25 patients (62.5 %) in 37 vascular territories. Quantitatively assessed significant stenosis and quantitatively assessed lesion length were independently associated with myocardial ischaemia (OR 7.72, 95 % CI 2.41-24.7, p 2 = 20.7) and lesion length (χ 2 = 26.0) to the clinical variables and the visual assessment (χ 2 = 5.9) had incremental value in the association with myocardial ischaemia. Coronary lesion length and quantitatively assessed significant stenosis were independently associated with myocardial ischaemia. Both quantitative parameters have incremental value over baseline variables and visually assessed significant stenosis. Potentially, QCT can refine assessment of CAD, which may be of potential use for identification of patients with myocardial ischaemia. (orig.)

  2. High-resolution 3D coronary vessel wall imaging with near 100% respiratory efficiency using epicardial fat tracking: reproducibility and comparison with standard methods.

    Science.gov (United States)

    Scott, Andrew D; Keegan, Jennifer; Firmin, David N

    2011-01-01

    To quantitatively assess the performance and reproducibility of 3D spiral coronary artery wall imaging with beat-to-beat respiratory-motion-correction (B2B-RMC) compared to navigator gated 2D spiral and turbo-spin-echo (TSE) acquisitions. High-resolution (0.7 × 0.7 mm) cross-sectional right coronary wall acquisitions were performed in 10 subjects using four techniques (B2B-RMC 3D spiral with alternate (2RR) and single (1RR) R-wave gating, navigator-gated 2D spiral (2RR) and navigator-gated 2D TSE (2RR)) on two occasions. Wall thickness measurements were compared with repeated measures analysis of variance (ANOVA). Reproducibility was assessed with the intraclass correlation coefficient (ICC). In all, 91% (73/80) of acquisitions were successful (failures: four TSE, two 3D spiral (1RR) and one 3D spiral (2RR)). Respiratory efficiency of the B2B-RMC was less variable and substantially higher than for navigator gating (99.6 ± 1.2% vs. 39.0 ± 7.5%, P B2B-RMC permits coronary vessel wall assessment over multiple thin contiguous slices in a clinically feasible duration. Excellent reproducibility of the technique potentially enables studies of disease progression/regression. Copyright © 2010 Wiley-Liss, Inc.

  3. A high performance gate drive for large gate turn off thyristors

    Energy Technology Data Exchange (ETDEWEB)

    Szilagyi, C.P.

    1993-01-01

    Past approaches to gate turn-off (GTO) gating are application oriented, inefficient and dissipate power even when inactive. They allow the gate to avalanch, and do not reduce GTO turn-on and turn-off losses. A new approach is proposed which will allow modular construction and adaptability to large GTOs in the 50 amp to 2000 amp range. The proposed gate driver can be used in large voltage source and current source inverters and other power converters. The approach consists of a power metal-oxide-silicon field effect transistor (MOSFET) technology gating unit, with associated logic and supervisory circuits and an isolated flyback converter as the dc power source for the gating unit. The gate driver formed by the gating unit and the flyback converter is designed for 4000 V isolation. Control and supervisory signals are exchanged between the gate driver and the remote control system via fiber optics. The gating unit has programmable front-porch current amplitude and pulse-width, programmable closed-loop controlled back-porch current, and a turn-off switch capable of supplying negative gate current at demand as a function of peak controllable forward anode current. The GTO turn-on, turn-off and gate avalanch losses are reduced to a minimum. The gate driver itself has minimum operating losses. Analysis, design and practical realization are reported. 19 refs., 54 figs., 1 tab.

  4. Integral diagnosis of coronary atherosclerosis by coronary multidetector computed tomography and by invasive coronary angiography

    International Nuclear Information System (INIS)

    Llerena Rojas, Luis Roberto; Llerena Rojas, Lorenzo D; Mendoza Rodriguez, Vladimir

    2013-01-01

    Coronary angiography by multidetector computed tomography (CMDCT) visualizes the wall and lumen of coronary arteries. Invasive coronary angiography (INVCA) only visualizes the arterial lumen but with better resolution

  5. A novel optical gating method for laser gated imaging

    Science.gov (United States)

    Ginat, Ran; Schneider, Ron; Zohar, Eyal; Nesher, Ofer

    2013-06-01

    For the past 15 years, Elbit Systems is developing time-resolved active laser-gated imaging (LGI) systems for various applications. Traditional LGI systems are based on high sensitive gated sensors, synchronized to pulsed laser sources. Elbit propriety multi-pulse per frame method, which is being implemented in LGI systems, improves significantly the imaging quality. A significant characteristic of the LGI is its ability to penetrate a disturbing media, such as rain, haze and some fog types. Current LGI systems are based on image intensifier (II) sensors, limiting the system in spectral response, image quality, reliability and cost. A novel propriety optical gating module was developed in Elbit, untying the dependency of LGI system on II. The optical gating module is not bounded to the radiance wavelength and positioned between the system optics and the sensor. This optical gating method supports the use of conventional solid state sensors. By selecting the appropriate solid state sensor, the new LGI systems can operate at any desired wavelength. In this paper we present the new gating method characteristics, performance and its advantages over the II gating method. The use of the gated imaging systems is described in a variety of applications, including results from latest field experiments.

  6. Initial evaluation of a practical PET respiratory motion correction method in clinical simultaneous PET/MRI

    International Nuclear Information System (INIS)

    Manber, Richard; Thielemans, Kris; Hutton, Brian; Barnes, Anna; Ourselin, Sebastien; Arridge, Simon; O’Meara, Celia; Atkinson, David

    2014-01-01

    Respiratory motion during PET acquisitions can cause image artefacts, with sharpness and tracer quantification adversely affected due to count ‘smearing’. Motion correction by registration of PET gates becomes increasingly difficult with shorter scan times and less counts. The advent of simultaneous PET/MRI scanners allows the use of high spatial resolution MRI to capture motion states during respiration [1, 2]. In this work, we use a respiratory signal derived from the PET list-mode data [3, ], with no requirement for an external device or MR sequence modifications.

  7. The management of respiratory motion in radiation oncology report of AAPM Task Group 76

    International Nuclear Information System (INIS)

    Keall, Paul J.; Mageras, Gig S.; Balter, James M.

    2006-01-01

    This document is the report of a task group of the AAPM and has been prepared primarily to advise medical physicists involved in the external-beam radiation therapy of patients with thoracic, abdominal, and pelvic tumors affected by respiratory motion. This report describes the magnitude of respiratory motion, discusses radiotherapy specific problems caused by respiratory motion, explains techniques that explicitly manage respiratory motion during radiotherapy and gives recommendations in the application of these techniques for patient care, including quality assurance (QA) guidelines for these devices and their use with conformal and intensity modulated radiotherapy. The technologies covered by this report are motion-encompassing methods, respiratory gated techniques, breath-hold techniques, forced shallow-breathing methods, and respiration-synchronized techniques. The main outcome of this report is a clinical process guide for managing respiratory motion. Included in this guide is the recommendation that tumor motion should be measured (when possible) for each patient for whom respiratory motion is a concern. If target motion is greater than 5 mm, a method of respiratory motion management is available, and if the patient can tolerate the procedure, respiratory motion management technology is appropriate. Respiratory motion management is also appropriate when the procedure will increase normal tissue sparing. Respiratory motion management involves further resources, education and the development of and adherence to QA procedures

  8. Multidetector CT of blunt cervical spine trauma in adults.

    Science.gov (United States)

    Dreizin, David; Letzing, Michael; Sliker, Clint W; Chokshi, Falgun H; Bodanapally, Uttam; Mirvis, Stuart E; Quencer, Robert M; Munera, Felipe

    2014-01-01

    A number of new developments in cervical spine imaging have transpired since the introduction of 64-section computed tomographic (CT) scanners in 2004. An increasing body of evidence favors the use of multidetector CT as a stand-alone screening test for excluding cervical injuries in polytrauma patients with obtundation. A new grading scale that is based on CT and magnetic resonance (MR) imaging findings, the cervical spine Subaxial Injury Classification and Scoring (SLIC) system, is gaining acceptance among spine surgeons. Radiographic measurements described for the evaluation of craniocervical distraction injuries are now being reevaluated with the use of multidetector CT. Although most patients with blunt trauma are now treated nonsurgically, evolution in the understanding of spinal stability, as well as the development of new surgical techniques and hardware, has driven management strategies that are increasingly favorable toward surgical intervention. It is therefore essential that radiologists recognize findings that distinguish injuries with ligamentous instability or a high likelihood of nonfusion that require surgical stabilization from those that are classically stable and can be treated with a collar or halo vest alone. The purpose of this article is to review the spectrum of cervical spine injuries, from the craniocervical junction through the subaxial spine, and present the most widely used grading systems for each injury type. ©RSNA, 2014.

  9. The Utility of 64 Channel Multidetector CT Angiography for Evaluating the Renal Vascular Anatomy and Possible Variations: a Pictorial Essay

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sheo; Neyaz, Zafar; Gupta, Archna [Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow (India)

    2010-06-15

    The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment.

  10. The utility of 64 channel multidetector CT angiography for evaluating the renal vascular anatomy and possible variations: a pictorial essay.

    Science.gov (United States)

    Kumar, Sheo; Neyaz, Zafar; Gupta, Archna

    2010-01-01

    The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment.

  11. The Utility of 64 Channel Multidetector CT Angiography for Evaluating the Renal Vascular Anatomy and Possible Variations: a Pictorial Essay

    International Nuclear Information System (INIS)

    Kumar, Sheo; Neyaz, Zafar; Gupta, Archna

    2010-01-01

    The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment

  12. An interactive videogame designed to improve respiratory navigator efficiency in children undergoing cardiovascular magnetic resonance.

    Science.gov (United States)

    Hamlet, Sean M; Haggerty, Christopher M; Suever, Jonathan D; Wehner, Gregory J; Grabau, Jonathan D; Andres, Kristin N; Vandsburger, Moriel H; Powell, David K; Sorrell, Vincent L; Fornwalt, Brandon K

    2016-09-06

    Advanced cardiovascular magnetic resonance (CMR) acquisitions often require long scan durations that necessitate respiratory navigator gating. The tradeoff of navigator gating is reduced scan efficiency, particularly when the patient's breathing patterns are inconsistent, as is commonly seen in children. We hypothesized that engaging pediatric participants with a navigator-controlled videogame to help control breathing patterns would improve navigator efficiency and maintain image quality. We developed custom software that processed the Siemens respiratory navigator image in real-time during CMR and represented diaphragm position using a cartoon avatar, which was projected to the participant in the scanner as visual feedback. The game incentivized children to breathe such that the avatar was positioned within the navigator acceptance window (±3 mm) throughout image acquisition. Using a 3T Siemens Tim Trio, 50 children (Age: 14 ± 3 years, 48 % female) with no significant past medical history underwent a respiratory navigator-gated 2D spiral cine displacement encoding with stimulated echoes (DENSE) CMR acquisition first with no feedback (NF) and then with the feedback game (FG). Thirty of the 50 children were randomized to undergo extensive off-scanner training with the FG using a MRI simulator, or no off-scanner training. Navigator efficiency, signal-to-noise ratio (SNR), and global left-ventricular strains were determined for each participant and compared. Using the FG improved average navigator efficiency from 33 ± 15 to 58 ± 13 % (p < 0.001) and improved SNR by 5 % (p = 0.01) compared to acquisitions with NF. There was no difference in navigator efficiency (p = 0.90) or SNR (p = 0.77) between untrained and trained participants for FG acquisitions. Circumferential and radial strains derived from FG acquisitions were slightly reduced compared to NF acquisitions (-16 ± 2 % vs -17 ± 2 %, p < 0.001; 40 ± 10

  13. Prevalence and Characteristics of Myocardial Bridging in Multidetector-Row Computed Tomography Coronary Angiography

    International Nuclear Information System (INIS)

    Carrascosa, Patricia; Martin Lopez, Elba; Capunay, Carlos; Deviggiano, Alejandro; Vallejos, Javier; Carrascosa, Jorge

    2009-01-01

    Background: Myocardial bridging (MB) are congenital defects of the coronary arteries in which a segment of an epicardial artery lies in the myocardium for part of its course. The current gold standard for diagnosing MB is coronary angiography; however other invasive techniques are also useful. Myocardial bridging can also be visualized with the use of novel non-invasive imaging techniques such as multidetector-row computed tomography coronary angiography (MDCT-CA). Objectives: To assess the prevalence and characteristics of myocardial bridging in patients undergoing multidetector-row computed tomography coronary angiography (MDCT-CA). Material and Methods: A total of 452 consecutive patients were evaluated with 16-row and 64-row MDCT-CA due to the presence of abnormal findings in myocardial perfusion image tests, symptoms suggestive of coronary artery disease, and in asymptomatic patients with a family history of coronary artery disease. The presence of MB, their location and characteristics were analyzed. Myocardial bridging were classified as complete and incomplete bridges with respect to continuity of the myocardium over the tunneled segment of the artery involved. Quantitative measurements of vessel diameter during systole and diastole were evaluated. Results: The prevalence of MB was 35.18%; 88 were complete and 71 incomplete. Among complete MB, 6 affected both systole and diastole, 27 presented only systolic compression and 55 showed no compression. Incomplete MB showed absence of arterial compression. Conclusions: Multidetector-row computed tomography coronary angiography detected a higher prevalence of MB in the study population and allowed to classify them and to assess their functional aspects throughout the cardiac cycle. (authors) [es

  14. Monte Carlo simulations with MENATE program in order to determine the characteristics of neutron multidetector

    International Nuclear Information System (INIS)

    Petrascu, M.; Isbasescu, Alina; Constantinescu, A.; Serban, S.; Stoica, I.V.

    2004-01-01

    The neutron multidetector consists of 81 detectors, made of 4x4x12 cmc BC-400 crystals mounted on XP2972 phototubes. This detector placed in the forward direction at 138 cm from the target, was used to detect the correlated neutrons in the fusion of Li11 halo nuclei with Si targets. To verify the criterion for selecting the true coincidences against cross-talk ( a spurious effect in which the same neutron is registered by two or more detectors) and to establish the optimal distance between adjacent detectors, the program MENATE ( written by P.Desesquelles, IPN - Orsay) was used to generate Monte Carlo neutrons and their interactions in multidetector. The results were analysed with PAW (from CERN Library). (authors)

  15. Comparison of cardiac gating and refocusing pulses for correction of cerebrospinal fluid pulsation artifacts in MR images

    International Nuclear Information System (INIS)

    Modic, M.T.; Haacke, E.M.; Lenz, G.W.; Masaryk, T.; Kaufman, B.; Ross, J.S.

    1986-01-01

    This study compared cardiac gating and additional refocusing gradient pulses in combination or alone for correction of cerebrospinal fluid (CSF) pulsation artifacts in both normal volunteers and in patients with suspected spinal pathology. Refocusing pulses or cardiac gating when used alone produced a decrease in ghosting artifacts on sagittal images and reduced the nonuniformity of the CSF signal on axial images. There is improved thin-section T2 imaging of the cord with long TEs and as few as one excitation. The refocusing pulses reduced ghosting artifacts also from respiratory motion and enhanced the CSF signal with shorter TRs leading to increased CSF contrast. When used together, the results were significantly better than either alone. Refocusing schemes can be used with any TR, do not require gating, and are now routinely employed at the authors' institution

  16. High-resolution imaging of pulmonary ventilation and perfusion with {sup 68}Ga-VQ respiratory gated (4-D) PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Callahan, Jason [Centre for Molecular Imaging, Peter MacCallum Cancer Centre, East Melbourne, VIC (Australia); Hofman, Michael S. [The University of Melbourne, Department of Medicine, Peter MacCallum Cancer Centre, Centre for Molecular Imaging, East Melbourne, VIC (Australia); Siva, Shankar [The University of Melbourne, Peter MacCallum Cancer Centre, Department of Radiation Oncology, East Melbourne, VIC (Australia); The University of Melbourne, Sir Peter MacCallum Department of Oncology, East Melbourne, VIC (Australia); Kron, Tomas [The University of Melbourne, Sir Peter MacCallum Department of Oncology, East Melbourne, VIC (Australia); The University of Melbourne, Peter MacCallum Cancer Centre, Department of Physical Sciences, East Melbourne, VIC (Australia); Schneider, Michal E. [Monash University, Department of Medical Imaging and Radiation Science, Clayton, VIC (Australia); Binns, David; Eu, Peter [Peter MacCallum Cancer Centre, Centre for Cancer Imaging, East Melbourne, VIC (Australia); Hicks, Rodney J. [The University of Melbourne, Sir Peter MacCallum Department of Oncology, Peter MacCallum Cancer Centre, Centre for Molecular Imaging, East Melbourne, VIC (Australia)

    2014-02-15

    Our group has previously reported on the use of {sup 68}Ga-ventilation/perfusion (VQ) PET/CT scanning for the diagnosis of pulmonary embolism. We describe here the acquisition methodology for {sup 68}Ga-VQ respiratory gated (4-D) PET/CT and the effects of respiratory motion on image coregistration in VQ scanning. A prospective study was performed in 15 patients with non-small-cell lung cancer. 4-D PET and 4-D CT images were acquired using an infrared marker on the patient's abdomen as a surrogate for breathing motion following inhalation of Galligas and intravenous administration of {sup 68}Ga-macroaggregated albumin. Images were reconstructed with phase-matched attenuation correction. The lungs were contoured on CT and PET VQ images during free-breathing (FB) and at maximum inspiration (Insp) and expiration (Exp). The similarity between PET and CT volumes was measured using the Dice coefficient (DC) comparing the following groups; (1) FB-PET/CT, (2) InspPET/InspCT, (3) ExpPET/Exp CT, and (4) FB-PET/AveCT. A repeated measures one-way ANOVA with multiple comparison Tukey tests were performed to evaluate any difference between the groups. Diaphragmatic motion in the superior-inferior direction on the 4-D CT scan was also measured. 4-D VQ scanning was successful in all patients without additional acquisition time compared to the nongated technique. The highest volume overlap was between ExpPET and ExpCT and between FB-PET and AveCT with a DC of 0.82 and 0.80 for ventilation and perfusion, respectively. This was significantly better than the DC comparing the other groups (0.78-0.79, p < 0.05). These values agreed with a visual inspection of the images with improved image coregistration around the lung bases. The diaphragmatic motion during the 4-D CT scan was highly variable with a range of 0.4-3.4 cm (SD 0.81 cm) in the right lung and 0-2.8 cm (SD 0.83 cm) in the left lung. Right-sided diaphragmatic nerve palsy was observed in 3 of 15 patients. {sup 68}Ga-VQ 4-D

  17. Multidetector computed tomography arteriography in the preoperative assessment of patients with ureteropelvic junction obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Petra [Department of Radiology, Hospital de la Plana, Ctra. de Vila-real a Borriana KM. 0.5, 12540 Vila-real (Spain)]. E-mail: PetraBraun@gmx.de; Guilabert, Jose Pamies [Department of Radiology, Hospital de la Plana, Ctra. de Vila-real a Borriana KM. 0.5, 12540 Vila-real (Spain); Kazmi, Faaiza [Department of Radiology, Penn State Milton S. Hershey Medical Center (United States)

    2007-01-15

    Background: Nowadays, endoscopic management of ureteropelvic junction (UPJ) obstruction is the treatment of choice. However, in the presence of crossing vessels, the success rate of endoscopic management decreases and the risk of hemorrhagic and vascular complications rises. The purpose of this study is to evaluate patients with UPJ obstruction using contrast enhanced multidetector computed tomography (CT) angiography to aid in surgical planning and management. Patients and methods: Between 2001 and 2005, 27 patients (mean age: 43 years; age range: 17-75 years) with UPJ obstruction were studied with multidetector CT angiography. Identification and characterization of crossing vessels was performed with multidirectional images and three-directional reconstructions. Results: 12 patients (44%) were found to have 16 crossing vessels (vessels in contact with the UPJ or within a vicinity of less than 2 mm). Nine of these vessels were arteries and seven were veins. Nine vessels crossed anteriorly, two posteriorly, and one anteromedially. Endopyelotomy was contraindicated in these 12 patients due to the presence of crossing vessels. Eleven out of the 12 patients underwent a pyeloplasty by open surgery or laparoscopy, where the presence of crossing vessels was confirmed. One of the 12 patients did not undergo surgery. Conclusion: Multidetector CT angiography permits an adequate preoperative assessment of patients with UPJ obstruction as it is able to identify the presence and location of crossing vessels. Furthermore, it allows to study in detail the anatomy of the renal area and its vascular variants.

  18. Prevalence of thoracolumbar vertebral fractures on multidetector CT

    International Nuclear Information System (INIS)

    Bartalena, Tommaso; Giannelli, Giovanni; Rinaldi, Maria Francesca; Rimondi, Eugenio; Rinaldi, Giovanni; Sverzellati, Nicola; Gavelli, Giampaolo

    2009-01-01

    Objective: To evaluate the prevalence of osteoporotic vertebral fractures in patients undergoing multidetector computed tomography (MDCT) of the chest and/or abdomen. Materials and methods: 323 consecutive patients (196 males, 127 females) with a mean age of 62.6 years (range 20-88) who had undergone chest and/or abdominal MDCT were evaluated. Sagittal reformats of the spine obtained from thin section datasets were reviewed by two radiologists and assessed for vertebral fractures. Morphometric analysis using electronic calipers was performed on vertebral bodies which appeared abnormal upon visual inspection. A vertebral body height loss of 15% or more was considered a fracture and graded as mild (15-24%), moderate (25-49%) or severe (more than 50%). Official radiology reports were reviewed and whether the vertebral fractures had been reported or not was noted. Results: 31 out of 323 patients (9.5%) had at least 1 vertebral fracture and 7 of those patients had multiple fractures for a total of 41 fractures. Morphometric grading revealed 10 mild, 16 moderate and 15 severe fractures. Prevalence was higher in women (14.1%) than men (6.6%) and increased with patients age with a 17.1% prevalence in post-menopausal women. Only 6 out 41 vertebral fractures (14.6%) had been noted in the radiology final report while the remaining 35 (85.45) had not. Conclusion: although vertebral fractures represent frequent incidental findings on multidetector CT studies and may be easily identified on sagittal reformats, they are often underreported by radiologists, most likely because of unawareness of their clinical importance.

  19. Respiratory correlated cone beam CT

    International Nuclear Information System (INIS)

    Sonke, Jan-Jakob; Zijp, Lambert; Remeijer, Peter; Herk, Marcel van

    2005-01-01

    conclusion, we have successfully implemented a respiratory correlated CBCT procedure yielding a 4D dataset. With respiratory correlated CBCT on a linear accelerator, the mean position, trajectory, and shape of a moving tumor can be verified just prior to treatment. Such verification reduces respiration induced geometrical uncertainties, enabling safe delivery of 4D radiotherapy such as gated radiotherapy with small margins

  20. Multidetector-row CT duodenography in familial adenomatous polyposis: a pilot study

    International Nuclear Information System (INIS)

    Taylor, S.A.; Halligan, S.; Moore, L.; Saunders, B.P.; Gallagher, M.; Phillips, R.K.S.; Bartram, C.I.

    2004-01-01

    AIM: To investigate the feasibility of using multidetector-row computed tomography (CT) duodenography to stage duodenal polyposis in patients with familial adenomatous polyposis. MATERIALS AND METHODS: Six patients underwent multidetector-row CT duodenography before upper gastrointestinal endoscopy. A single-blinded radiologist used a surface shaded three-dimensional endoluminal fly though and two-dimensional axial and multiplanar reformats to assign a score for maximum polyp size and number based on the Spigelman classification. Comparison was made with the corresponding Spigelman scores obtained from subsequent endoscopy. RESULTS: CT duodenography was technically successful in five of six patients. The CT derived Spigelman score based on maximum polyp size was accurate in all five patients. The CT derived Spigelman score based on polyp number was accurate in only two cases: Polyp number was overestimated in one patient and underestimated in a further two. In retrospect, fine carpeting of tiny duodenal polyps was poorly visualized with CT. CONCLUSIONS: CT duodenography is technically feasible and accurately predicts maximum polyp size but CT estimates of polyp number are relatively inaccurate. CT duodenography potentially has a useful role for duodenal surveillance in those patients intolerant of conventional endoscopy

  1. Radiotherapy for breast cancer: respiratory and set-up uncertainties

    International Nuclear Information System (INIS)

    Saliou, M.G.; Giraud, P.; Simon, L.; Fournier-Bidoz, N.; Fourquet, A.; Dendale, R.; Rosenwald, J.C.; Cosset, J.M.

    2005-01-01

    Adjuvant Radiotherapy has been shown to significantly reduce locoregional recurrence but this advantage is associated with increased cardiovascular and pulmonary morbidities. All uncertainties inherent to conformal radiation therapy must be identified in order to increase the precision of treatment; misestimation of these uncertainties increases the potential risk of geometrical misses with, as a consequence, under-dosage of the tumor and/or overdosage of healthy tissues. Geometric uncertainties due to respiratory movements or set-up errors are well known. Two strategies have been proposed to limit their effect: quantification of these uncertainties, which are then taken into account in the final calculation of safety margins and/or reduction of respiratory and set-up uncertainties by an efficient immobilization or gating systems. Measured on portal films with two tangential fields. CLD (central lung distance), defined as the distance between the deep field edge and the interior chest wall at the central axis, seems to be the best predictor of set-up uncertainties. Using CLD, estimated mean set-up errors from the literature are 3.8 and 3.2 mm for the systematic and random errors respectively. These depend partly on the type of immobilization device and could be reduced by the use of portal imaging systems. Furthermore, breast is mobile during respiration with motion amplitude as high as 0.8 to 10 mm in the anteroposterior direction. Respiratory gating techniques, currently on evaluation, have the potential to reduce effect of these movements. Each radiotherapy department should perform its own assessments and determine the geometric uncertainties with respect of the equipment used and its particular treatment practices. This paper is a review of the main geometric uncertainties in breast treatment, due to respiration and set-up, and solutions proposed to limit their impact. (author)

  2. Gating treatment delivery QA based on a surrogate motion analysis

    International Nuclear Information System (INIS)

    Chojnowski, J.; Simpson, E.

    2011-01-01

    Full text: To develop a methodology to estimate intrafractional target position error during a phase-based gated treatment. Westmead Cancer Care Centre is using respiratory correlated phase-based gated beam delivery in the treatment of lung cancer. The gating technique is managed by the Varian Real-time Position Management (RPM) system, version 1.7.5. A 6-dot block is placed on the abdomen of the patient and acts as a surrogate for the target motion. During a treatment session, the motion of the surrogate can be recorded by RPM application. Analysis of the surrogate motion file by in-house developed software allows the intrafractional error of the treatment session to be computed. To validate the computed error, a simple test that involves the introduction of deliberate errors is performed. Errors of up to 1.1 cm are introduced to a metal marker placed on a surrogate using the Varian Breathing Phantom. The moving marker was scanned in prospective mode using a GE Lightspeed 16 CT scanner. Using the CT images, a difference of the marker position with and without introduced errors is compared to the calculated errors based on the surrogate motion. The average and standard deviation of a difference between calculated target position errors and measured introduced artificial errors of the marker position is 0.02 cm and 0.07 cm respectively. Conclusion The calculated target positional error based on surrogate motion analysis provides a quantitative measure of intrafractional target positional errors during treatment. Routine QA for gated treatment using surrogate motion analysis is relatively quick and simple.

  3. Spirometrically gated 133Xe ventilation imaging and phase analysis for assessment of regional lung function

    International Nuclear Information System (INIS)

    Inoue, Tomio

    1984-01-01

    The purpose of this study is to develop the technique of performing spirometrically gated 133 Xe ventilation imaging and to evaluate its clinical usefulness for the assessmentof regional ventilatory function in various lung diseases. Patients rebreathe d 133 Xe gas through the system with constant rates signaled by a metronom. The trigger signals from the patients were recorded in a minicomputer for 60 respiratory cycles simultaneously with posterior lung images. Functional images (phase analysis images) indicating phase and amplitude of regional ventilation were constructed by the first harmonic Fourier analysis. Materials included 13 normal volunteers and patients with COPD (24), lung cancer (5), pulmonary embolism (4) and others (20). In normal controls, phase analysis images before respiratory motion correction revealed gradual decrease in amplitude from base to apex with uniform phase distribution. The amplitude and phase distribution after respiratory motion correction became even more uniform. In patients with COPD, phase analysis images showed asymmetrical and irregular amplitude distribution with non-uniform phase distribution. The standard deviation (S.D.) of phase histogram correlated well with FEVsub(1.0)% (r=0.71, p<0.001) and down slope of flowvolume curve (r=0.55, p<0.001), and less prominently with %VC (r=0.42, p<0.01). Mean S.D. in patients with COPD (12.3+-6.5 degree, mean+-1 s.d.) was significantly larger than in normal controls (6.3+-1.5). Amplitude profile curve analysis revealed 83% sensitivity for the detection of abnormal spirometric respiratory function test. Data aquisition and processing of present method are rapid and easy to perform. The phase analysis of the gated ventilation images should prove useful in the clinical evaluation of patients with uneven ventilation such as COPD. (J.P.N.)

  4. Design and development of a new pulsating cardiac coronary phantom for ECG-gated CT and its experimental characteristics

    International Nuclear Information System (INIS)

    Shen, Yun; Sato, Munekuni; Kimura, Fumiko; Jinzaki, Masahiro; Kuribayashi, Sachio; Horiguchi, Jun; Ito, Katsuhide

    2005-01-01

    The optimal pulsating cardiac phantom is an important tool for the evaluation of cardiac images and cardiac applications on electrocardiogram (ECG)-gated multidetector-row CT (MDCT). The purpose of this study was to demonstrate the design and fabrication of the pulsating cardiac coronary phantom. The newly developed pulsating cardiac coronary phantom has the following five key advantages: a driver component that uses only one servomotor to move the phantom in three dimensions (X, Y, and Z directions) with 16 presets of different heart types (heartbeat: 0-120 bpm; ejection fraction: 0-90%); versatile pumping and filling phases to simulate a real heart in a cardiac cycle can be incorporated into the driver sequence including shift of patient heartbeat or irregular pulse (maximum: 200 different heart waves in one scan); a cardiac coronary component constituted of an acrylic/silicon/rubber tube (2-6 mm inner diameter) with stent/in-stent restenosis/stenosis/soft plaque/calcification parts and maximum 16 coronary arteries that can be attached to the phantom in the same scan; the complete phantom can be submerged in a tank to simulate the heart and its surrounding tissues; ECG gating can be from interior trigger and exterior trigger. It has been confirmed that the developed pulsating cardiac phantom is very useful to quantitatively assess imaging of the heart and coronary arteries during phantom experiments. (author)

  5. Examination of geometric and dosimetric accuracies of gated step-and-shoot intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    Wiersma, R. D.; Xing, L.

    2007-01-01

    Due to the complicated technical nature of gated radiation therapy, electronic and mechanical limitations may affect the precision of delivery. The purpose of this study is to investigate the geometric and dosimetric accuracies of gated step-and-shoot intensity modulated radiation treatments (SS-IMRT). Unique segmental MLC plans are designed, which allow quantitative testing of the gating process. Both ungated and gated deliveries are investigated for different dose sizes, dose rates, and gating window times using a commercial treatment system (Varian Trilogy) together with a respiratory gating system [Varian Real-Time Position Management system]. Radiographic film measurements are used to study the geometric accuracy, where it is found that with both ungated and gated SS-IMRT deliveries the MLC leaf divergence away from planned is less than or equal to the MLC specified leaf tolerance value for all leafs (leaf tolerance being settable from 0.5-5 mm). Nevertheless, due to the MLC controller design, failure to define a specific leaf tolerance value suitable to the SS-IMRT plan can lead to undesired geometric effects, such as leaf motion of up to the maximum 5 mm leaf tolerance value occurring after the beam is turned on. In this case, gating may be advantageous over the ungated case, as it allows more time for the MLC to reach the intended leaf configuration. The dosimetric precision of gated SS-IMRT is investigated using ionization chamber methods. Compared with the ungated case, it is found that gating generally leads to increased dosimetric errors due to the interruption of the ''overshoot phenomena.'' With gating the average timing deviation for intermediate segments is found to be 27 ms, compared to 18 ms for the ungated case. For a plan delivered at 600 MU/min this would correspond to an average segment dose error of ∼0.27 MU and ∼0.18 MU for gated and ungated deliveries, respectively. The maximum dosimetric errors for individual intermediate segments are

  6. Multidetector-row computed tomography for prosthetic heart valve dysfunction: is concomitant non-invasive coronary angiography possible before redo-surgery?

    Energy Technology Data Exchange (ETDEWEB)

    Tanis, Wilco [Haga Teaching Hospital, Department of Cardiology, The Hague (Netherlands); Haga Teaching Hospital, The Hague (Netherlands); Sucha, Dominika; Habets, Jesse [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Laufer, Ward; Chamuleau, Steven [University Medical Center Utrecht, Department of Cardiology, Utrecht (Netherlands); Herwerden, Lex.A. van [University Medical Center Utrecht, Department of Cardiothoracic Surgery, Utrecht (Netherlands); Symersky, Petr [Vrije Universiteit, Department of Cardiothoracic Surgery, Amsterdam (Netherlands); Budde, Ricardo P.J. [Erasmus Medical Center, Department of Radiology, Rotterdam (Netherlands)

    2015-06-01

    Retrospective ECG-gated multidetector-row computed tomography (MDCT) is increasingly used for the assessment of prosthetic heart valve (PHV) dysfunction, but is also hampered by PHV-related artefacts/cardiac arrhythmias. Furthermore, it is performed without nitroglycerine or heart rate correction. The purpose was to determine whether MDCT performed before potential redo-PHV surgery is feasible for concomitant coronary artery stenosis assessment and can replace invasive coronary angiography (CAG). PHV patients with CAG and MDCT were identified. Based on medical history, two groups were created: (I) patients with no known coronary artery disease (CAD), (II) patients with known CAD. All images were scored for the presence of significant (>50 %) stenosis. CAG was the reference test. Fifty-one patients were included. In group I (n = 38), MDCT accurately ruled out significant stenosis in 19/38 (50 %) patients, but could not replace CAG in the remaining 19/38 (50 %) patients due to non-diagnostic image quality (n = 16) or significant stenosis (n = 3) detection. In group II (n = 13), MDCT correctly found no patients without significant stenosis, requiring CAG imaging in all. MDCT assessed patency in 16/19 (84 %) grafts and detected a hostile anatomy in two. MDCT performed for PHV dysfunction assessment can replace CAG (100 % accurate) in approximately half of patients without previously known CAD. (orig.)

  7. Multidetector-row computed tomography for prosthetic heart valve dysfunction: is concomitant non-invasive coronary angiography possible before redo-surgery?

    International Nuclear Information System (INIS)

    Tanis, Wilco; Sucha, Dominika; Habets, Jesse; Laufer, Ward; Chamuleau, Steven; Herwerden, Lex.A. van; Symersky, Petr; Budde, Ricardo P.J.

    2015-01-01

    Retrospective ECG-gated multidetector-row computed tomography (MDCT) is increasingly used for the assessment of prosthetic heart valve (PHV) dysfunction, but is also hampered by PHV-related artefacts/cardiac arrhythmias. Furthermore, it is performed without nitroglycerine or heart rate correction. The purpose was to determine whether MDCT performed before potential redo-PHV surgery is feasible for concomitant coronary artery stenosis assessment and can replace invasive coronary angiography (CAG). PHV patients with CAG and MDCT were identified. Based on medical history, two groups were created: (I) patients with no known coronary artery disease (CAD), (II) patients with known CAD. All images were scored for the presence of significant (>50 %) stenosis. CAG was the reference test. Fifty-one patients were included. In group I (n = 38), MDCT accurately ruled out significant stenosis in 19/38 (50 %) patients, but could not replace CAG in the remaining 19/38 (50 %) patients due to non-diagnostic image quality (n = 16) or significant stenosis (n = 3) detection. In group II (n = 13), MDCT correctly found no patients without significant stenosis, requiring CAG imaging in all. MDCT assessed patency in 16/19 (84 %) grafts and detected a hostile anatomy in two. MDCT performed for PHV dysfunction assessment can replace CAG (100 % accurate) in approximately half of patients without previously known CAD. (orig.)

  8. Evaluation of image quality and radiation dose at prospective ECG-triggered axial 256-slice multi-detector CT in infants with congenital heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Mei-ping; Liang, Chang-hong; Zhao, Zhen-jun; Liu, Hui; Li, Jing-lei; Zhang, Jin-e; Cui, Yan-hai; Yang, Lin; Liu, Qi-shun [Guangdong Academy of Medical Sciences, Guangdong General Hospital, Department of Radiology, Guangzhou (China); Ivanc, Thomas B.; Vembar, Mani [Philips Healthcare, CT Clinical Science, Highland Heights, OH (United States)

    2011-07-15

    There are a limited number of reports on the technical and clinical feasibility of prospective electrocardiogram (ECG)-gated multi-detector computed tomography (MDCT) in infants with congenital heart disease (CHD). To evaluate image quality and radiation dose at weight-based low-dose prospectively gated 256-slice MDCT angiography in infants with CHD. From November 2009 to February 2010, 64 consecutive infants with CHD referred for pre-operative or post-operative CT were included. All were scanned on a 256-slice MDCT system utilizing a low-dose protocol (80 kVp and 60-120 mAs depending on weight: 60 mAs for {<=}3 kg, 80 mAs for 3.1-6 kg, 100 mAs for 6.1-10 kg, 120 mAs for 10.1-15 kg). No serious adverse events were recorded. A total of 174 cardiac deformities, confirmed by surgery or heart catheterization, were studied. The sensitivity of MDCT for cardiac deformities was 97.1%; specificity, 99.4%; accuracy, 95.9%. The mean heart rate during scan was 136.7 {+-} 14.9/min (range, 91-160) with a corresponding heart rate variability of 2.8 {+-} 2.2/min (range, 0-8). Mean scan length was 115.3 {+-} 11.7 mm (range, 93.6-143.3). Mean volume CT dose index, mean dose-length product and effective dose were 2.1 {+-} 0.4 mGy (range, 1.5-2.8), 24.7 {+-} 5.9 mGy.cm (range, 14.7-35.8) and 1.6 {+-} 0.3 mSv (range, 1.1-2.5), respectively. Diagnostic-quality images were achieved in all cases. Satisfactory diagnostic quality for visualization of all/proximal/distal coronary artery segments was achieved in 88.4/98.8/80.0% of the scans. Low-dose prospectively gated axial 256-slice CT angiography is a valuable tool in the routine clinical evaluation of infants with CHD, providing a comprehensive three-dimensional evaluation of the cardiac anatomy, including the coronary arteries. (orig.)

  9. Delineation of the anatomical relationship of innominate artery and trachea by respiratory-gated MR imaging with true FISP sequence in patients with severe motor and intellectual disabilities

    International Nuclear Information System (INIS)

    Fujikawa, Yoshinao; Sato, Noriko; Sugai, Kenji; Endo, Yusaku; Matsufuji, Hiroki; Oomi, Tsuyoshi; Honzawa, Shiho; Sasaki, Masayuki

    2008-01-01

    Tracheoinnominate artery fistula is a well-known complication that arises on using a cannula. Therefore, routine examination of the anatomical relationship of the innominate artery and trachea should be carried out. We evaluated the usefulness of magnetic resonance imaging in 5 patients with severe motor and intellectual disabilities (SMID) using a combination of true-fast imaging of steady-state precession (true-FISP) sequences and two-dimensional prospective acquisition correction (2D-PACE). For all patients, the trachea and the innominate artery were identified without sedation and contrast media. In one patient, the innominate artery was observed to be pressing on the trachea. In three patients, the trachea and innominate artery were brought very close each other, and in the other patient the anatomical relationship of the trachea and surrounding structure was delineated before tracheotomy. The validity of true-FISP sequences combined with the respiratory-gated technique was confirmed useful for the patients who are difficult to lie quietly and to hold their breath voluntarily. (author)

  10. Respiratory motion correction for PET oncology applications using affine transformation of list mode data

    International Nuclear Information System (INIS)

    Lamare, F; Cresson, T; Savean, J; Rest, C Cheze Le; Reader, A J; Visvikis, D

    2007-01-01

    Respiratory motion is a source of artefacts and reduced image quality in PET. Proposed methodology for correction of respiratory effects involves the use of gated frames, which are however of low signal-to-noise ratio. Therefore a method accounting for respiratory motion effects without affecting the statistical quality of the reconstructed images is necessary. We have implemented an affine transformation of list mode data for the correction of respiratory motion over the thorax. The study was performed using datasets of the NCAT phantom at different points throughout the respiratory cycle. List mode data based PET simulated frames were produced by combining the NCAT datasets with a Monte Carlo simulation. Transformation parameters accounting for respiratory motion were estimated according to an affine registration and were subsequently applied on the original list mode data. The corrected and uncorrected list mode datasets were subsequently reconstructed using the one-pass list mode EM (OPL-EM) algorithm. Comparison of corrected and uncorrected respiratory motion average frames suggests that an affine transformation in the list mode data prior to reconstruction can produce significant improvements in accounting for respiratory motion artefacts in the lungs and heart. However, the application of a common set of transformation parameters across the imaging field of view does not significantly correct the respiratory effects on organs such as the stomach, liver or spleen

  11. Development of a charged particle multidetector and application to physics at the Vivitron accelerator

    International Nuclear Information System (INIS)

    Belier, G.

    1994-05-01

    The charged particle multidetector ICARE is an apparatus designed for the Vivitron accelerator, with the aim to study both heavy ions reaction mechanisms and the structure of the nuclei. It will be able to work independently with its own electronic and acquisition system as well as in association with other types of multidetectors (Eurogam, Demon, ...). The development of ICARE is based on compactness and modularity criteria and takes into account the expected multiplicities and energies of the particles to be detected. It is composed of 48 compact telescopes of low energy threshold, 8 of them being heavy ion telescopes (Z 147 Gd superdeformed states of highest angular momenta. In the gamma ray spectra detected by the Eurogam array in coincidence with fission fragments, a positive contribution corresponding to energy differences are observed, which are consistent with the emission by superdeformed states. (from author) 64 figs., 12 tabs., 91 refs

  12. 64 multidetector CT findings of influenza A (H1N1) virus in patients with hematologic malignancies

    International Nuclear Information System (INIS)

    El-Badrawy, Adel; Zeidan, Amany; Ebrahim, Mohamed A.

    2012-01-01

    Background. The pandemic of swine-origin H1N1 influenza that began in early 2009 has provided evidence that radiology can assist in the early diagnosis of severe cases. Immunocompromised patients are at increased risk for morbidity and mortality. MDCT is superior to radiography in showing the distribution of the disease. Purpose. To review the 64 multidetector CT thoracic findings of novel swine-origin influenza A (H1N1) virus in patients with hematologic malignancies. Material and Methods. This study included 12 patients (3 women, 9 men; mean age, 32.2 years). All patients proved to be infected with influenza A (H1N1) virus. The hematologic malignancies were acute myeloid leukemia (n = 8), chronic lymphocytic leukemia (n = 2), multiple myeloma (n = 1), and myelodysplastic syndrome (n = 1). All the patients underwent CT scanning using a 64 multidetector CT scanner. Chest CT scans were reviewed for ground-glass opacities (GGOs), consolidation, airway thickening/dilatation, nodules, mediastinal lymphadenopathy, and pleural effusion. Results. More than one CT finding was detected in every patient. Pulmonary affection was bilateral, more on the left side. The affections were mainly peribronchial. Airway wall thickening and dilatation were detected in all 12 patients, GGO in 9/12 patients, nodules in 6/12 patients, consolidation in 6/12 patients, hilar lymphadenopathy in 3/12 patients, and pleural effusion in 2/12 patients. Conclusion. Acute myeloid leukemia is the most common hematologic malignancy affected by influenza A (H1N1) virus. The left lung is affected more than the right one. The most common multidetector CT findings are unilateral or bilateral airway thickening and dilatation. Multidetector CT can be used for early and accurate assessment of pulmonary affection with influenza A H1N1 virus infection

  13. Usefulness of multiplanar reformatted images of multi-detector row helical CT in assessment of biliary stent patency

    International Nuclear Information System (INIS)

    Kim, Soo Jin; Kim, Suk; Kim, Chang Won; Lee, Jun Woo; Lee, Tae Hong; Choo, Ki Seok; Koo, Young Baek; Moon, Tae Yong; Lee, Suk Hong

    2004-01-01

    To evaluate the usefulness of multi-detector row helical CT (MDCT), multiplanar reformatted images for the noninvasive assessment of biliary stent patency, and for the planning for management in patients with a sele-expandable metallic stent due to malignant biliary obstruction. Among 90 consecutive patients, from August 1999 to July 2003, 26 cases in 23 patients with malignant biliary obstruction who underwent self-expandable metaIlic stent insertion in the biliary system and percutaneous transhepatic biliary drainage within 7 days after CT were enrolled in this study. On CT images, the complete and functional obstruction of the stent and the precise level of obstruction were evaluated. The presence of an enhancing intraluminal mass or wall thickening around stent was determined, and the causes of obstruction were evaluated. These findings were then compared with percutaneous transhepatic cholangiography. Multi-detector row helical CT correctly demonstrated the patency of a stent in 24 cases (92.3%). It was adequate in helping to depict the precise level of stent occlusion in 23 cases (88.5%). Multi-detector row helical CT also revealed the extent of tumor that represented as an enhancing intraluminal mass or wall thickening around the stent in 23 cases, and this was represented as complete obstruction on percutaneous transhepatic cholangiography. In the case of functional obstruction, MDCT predicted the possible cause of the obstruction. Multiplanar reformatted images of multi-detector row helical CT is a useful imaging modality for the noninvasive assessment of stent patency and the precise level of obstruction when stent obstruction is suspected in the patients with self-expandable metallic stent due to malignant biliary obstruction. It can also predict the possible cause of the obstruction and allows adequate planning for the medical management of such cases

  14. Usefulness of multiplanar reformatted images of multi-detector row helical CT in assessment of biliary stent patency

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soo Jin; Kim, Suk; Kim, Chang Won; Lee, Jun Woo; Lee, Tae Hong; Choo, Ki Seok; Koo, Young Baek; Moon, Tae Yong; Lee, Suk Hong [Pusan National Univ. Hospital, Busan (Korea, Republic of)

    2004-08-01

    To evaluate the usefulness of multi-detector row helical CT (MDCT), multiplanar reformatted images for the noninvasive assessment of biliary stent patency, and for the planning for management in patients with a sele-expandable metallic stent due to malignant biliary obstruction. Among 90 consecutive patients, from August 1999 to July 2003, 26 cases in 23 patients with malignant biliary obstruction who underwent self-expandable metaIlic stent insertion in the biliary system and percutaneous transhepatic biliary drainage within 7 days after CT were enrolled in this study. On CT images, the complete and functional obstruction of the stent and the precise level of obstruction were evaluated. The presence of an enhancing intraluminal mass or wall thickening around stent was determined, and the causes of obstruction were evaluated. These findings were then compared with percutaneous transhepatic cholangiography. Multi-detector row helical CT correctly demonstrated the patency of a stent in 24 cases (92.3%). It was adequate in helping to depict the precise level of stent occlusion in 23 cases (88.5%). Multi-detector row helical CT also revealed the extent of tumor that represented as an enhancing intraluminal mass or wall thickening around the stent in 23 cases, and this was represented as complete obstruction on percutaneous transhepatic cholangiography. In the case of functional obstruction, MDCT predicted the possible cause of the obstruction. Multiplanar reformatted images of multi-detector row helical CT is a useful imaging modality for the noninvasive assessment of stent patency and the precise level of obstruction when stent obstruction is suspected in the patients with self-expandable metallic stent due to malignant biliary obstruction. It can also predict the possible cause of the obstruction and allows adequate planning for the medical management of such cases.

  15. 64 multidetector CT findings of influenza A (H1N1) virus in patients with hematologic malignancies

    Energy Technology Data Exchange (ETDEWEB)

    El-Badrawy, Adel [Dept. of Radiology, Mansoura Faculty of Medicine, Mansoura (Egypt)], E-mail: adelelbadrawy@hotmail.com; Zeidan, Amany [Dept. of Thoracic Medicine, Mansoura Faculty of Medicine, Mansoura (Egypt); Ebrahim, Mohamed A. [Dept. of Medical Oncology, Mansoura Faculty of Medicine, Mansoura (Egypt)

    2012-07-15

    Background. The pandemic of swine-origin H1N1 influenza that began in early 2009 has provided evidence that radiology can assist in the early diagnosis of severe cases. Immunocompromised patients are at increased risk for morbidity and mortality. MDCT is superior to radiography in showing the distribution of the disease. Purpose. To review the 64 multidetector CT thoracic findings of novel swine-origin influenza A (H1N1) virus in patients with hematologic malignancies. Material and Methods. This study included 12 patients (3 women, 9 men; mean age, 32.2 years). All patients proved to be infected with influenza A (H1N1) virus. The hematologic malignancies were acute myeloid leukemia (n = 8), chronic lymphocytic leukemia (n = 2), multiple myeloma (n = 1), and myelodysplastic syndrome (n = 1). All the patients underwent CT scanning using a 64 multidetector CT scanner. Chest CT scans were reviewed for ground-glass opacities (GGOs), consolidation, airway thickening/dilatation, nodules, mediastinal lymphadenopathy, and pleural effusion. Results. More than one CT finding was detected in every patient. Pulmonary affection was bilateral, more on the left side. The affections were mainly peribronchial. Airway wall thickening and dilatation were detected in all 12 patients, GGO in 9/12 patients, nodules in 6/12 patients, consolidation in 6/12 patients, hilar lymphadenopathy in 3/12 patients, and pleural effusion in 2/12 patients. Conclusion. Acute myeloid leukemia is the most common hematologic malignancy affected by influenza A (H1N1) virus. The left lung is affected more than the right one. The most common multidetector CT findings are unilateral or bilateral airway thickening and dilatation. Multidetector CT can be used for early and accurate assessment of pulmonary affection with influenza A H1N1 virus infection.

  16. Linear gate

    International Nuclear Information System (INIS)

    Suwono.

    1978-01-01

    A linear gate providing a variable gate duration from 0,40μsec to 4μsec was developed. The electronic circuity consists of a linear circuit and an enable circuit. The input signal can be either unipolar or bipolar. If the input signal is bipolar, the negative portion will be filtered. The operation of the linear gate is controlled by the application of a positive enable pulse. (author)

  17. Early-life exposure to indoor air pollution or tobacco smoke and lower respiratory tract illness and wheezing in African infants: a longitudinal birth cohort study

    Directory of Open Access Journals (Sweden)

    Dr Aneesa Vanker, FCPaed

    2017-11-01

    Funding: Bill & Melinda Gates Foundation, Discovery Foundation, South African Thoracic Society AstraZeneca Respiratory Fellowship, Medical Research Council South Africa, National Research Foundation South Africa, and CIDRI Clinical Fellowship.

  18. Multidetector-row CT finding of gastric cystic lymphangioma: A case report

    International Nuclear Information System (INIS)

    Kang, Tae Wook; Lee, Soon Jin; Song, Hye Jong

    2008-01-01

    Cystic lymphangioma is a rare benign submucosal tumor of the stomach thought to originate from sequestered lymphatic tissue that fails to communicate with the normal lymphatic system. The most commonly used method of evaluation for cystic lymphangioma of the stomach is an endoscopic ultrasonography. We report the multidetector-row computed tomography findings of a cystic lymphangioma of the stomach in a 46-year-old man along with a literature review

  19. Observation of Interfractional Variations in Lung Tumor Position Using Respiratory Gated and Ungated Megavoltage Cone-Beam Computed Tomography

    International Nuclear Information System (INIS)

    Chang, Jenghwa; Mageras, Gig S.; Yorke, Ellen; De Arruda, Fernando; Sillanpaa, Jussi; Rosenzweig, Kenneth E.; Hertanto, Agung; Pham, Hai; Seppi, Edward; Pevsner, Alex; Ling, C. Clifton; Amols, Howard

    2007-01-01

    Purpose: To evaluate the use of megavoltage cone-beam computed tomography (MV CBCT) to measure interfractional variation in lung tumor position. Methods and Materials: Eight non-small-cell lung cancer patients participated in the study, 4 with respiratory gating and 4 without. All patients underwent MV CBCT scanning at weekly intervals. Contoured planning CT and MV CBCT images were spatially registered based on vertebral anatomy, and displacements of the tumor centroid determined. Setup error was assessed by comparing weekly portal orthogonal radiographs with digitally reconstructed radiographs generated from planning CT images. Hypothesis testing was performed to test the statistical significance of the volume difference, centroid displacement, and setup uncertainty. Results: The vertebral bodies and soft tissue portions of tumor within lung were visible on the MV CBCT scans. Statistically significant systematic volume decrease over the course of treatment was observed for 1 patient. The average centroid displacement between simulation CT and MV CBCT scans were 2.5 mm, -2.0 mm, and -1.5 mm with standard deviations of 2.7 mm, 2.7 mm, and 2.6 mm in the right-left, anterior-posterior and superior-inferior directions. The mean setup errors were smaller than the centroid shifts, while the standard deviations were comparable. In most cases, the gross tumor volume (GTV) defined on the MV CBCT was located on average at least 5 mm inside a 10 mm expansion of the GTV defined on the planning CT scan. Conclusions: The MV CBCT technique can be used to image lung tumors and may prove valuable for image-guided radiotherapy. Our conclusions must be verified in view of the small patient number

  20. Reproducibility of multi-detector spiral computed tomography in detection of sub-segmental acute pulmonary embolism

    International Nuclear Information System (INIS)

    Brunot, S.; Corneloup, O.; Latrabe, V.; Montaudon, M.; Laurent, F.

    2005-01-01

    The aim of this study was to evaluate the inter-observer and intra-observer agreement of the diagnosis of sub-segmental acute pulmonary embolism (PE) in an inpatient population explored by 16 slice multi-detector spiral computed tomography (MDCT). Four hundred consecutive inpatients were referred for MDCT for the clinical suspicion of acute PE. One hundred and seventy seven (44.2%) had a known cardio-respiratory disease at the time of examination. Inter-observer and intra-observer agreements for the diagnosis of acute PE and of sub-segmental acute PE were assessed blind and independently by three experienced readers and by kappa statistics. Seventy-five patients were diagnosed as having acute PE findings (19.5%), and clots were located exclusively within sub-segmental arteries in nine patients (12%). When clots were limited to sub-segmental or more distal branches of the pulmonary arteries, kappa values were found to be moderate (0.56) to very good (0.85) for the diagnosis of sub-segmental acute PE, whereas for the diagnosis of acute PE in the whole population, kappa values ranged from 0.84 to 0.97. Intra-observer agreement was found to be perfect (kappa=1). MDCT is a reproducible technique for the diagnosis of sub-segmental acute PE as well as for acute PE. In this inpatient population, sub-segmental acute PE was not a rare event. (orig.)

  1. A finite state model for respiratory motion analysis in image guided radiation therapy

    International Nuclear Information System (INIS)

    Wu Huanmei; Sharp, Gregory C; Salzberg, Betty; Kaeli, David; Shirato, Hiroki; Jiang, Steve B

    2004-01-01

    Effective image guided radiation treatment of a moving tumour requires adequate information on respiratory motion characteristics. For margin expansion, beam tracking and respiratory gating, the tumour motion must be quantified for pretreatment planning and monitored on-line. We propose a finite state model for respiratory motion analysis that captures our natural understanding of breathing stages. In this model, a regular breathing cycle is represented by three line segments, exhale, end-of-exhale and inhale, while abnormal breathing is represented by an irregular breathing state. In addition, we describe an on-line implementation of this model in one dimension. We found this model can accurately characterize a wide variety of patient breathing patterns. This model was used to describe the respiratory motion for 23 patients with peak-to-peak motion greater than 7 mm. The average root mean square error over all patients was less than 1 mm and no patient has an error worse than 1.5 mm. Our model provides a convenient tool to quantify respiratory motion characteristics, such as patterns of frequency changes and amplitude changes, and can be applied to internal or external motion, including internal tumour position, abdominal surface, diaphragm, spirometry and other surrogates

  2. A finite state model for respiratory motion analysis in image guided radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Huanmei [College of Computer and Information Science, Northeastern University, Boston, MA 02115 (United States); Sharp, Gregory C [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114 (United States); Salzberg, Betty [College of Computer and Information Science, Northeastern University, Boston, MA 02115 (United States); Kaeli, David [Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States); Shirato, Hiroki [Department of Radiation Medicine, Hokkaido University School of Medicine, Sapporo (Japan); Jiang, Steve B [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114 (United States)

    2004-12-07

    Effective image guided radiation treatment of a moving tumour requires adequate information on respiratory motion characteristics. For margin expansion, beam tracking and respiratory gating, the tumour motion must be quantified for pretreatment planning and monitored on-line. We propose a finite state model for respiratory motion analysis that captures our natural understanding of breathing stages. In this model, a regular breathing cycle is represented by three line segments, exhale, end-of-exhale and inhale, while abnormal breathing is represented by an irregular breathing state. In addition, we describe an on-line implementation of this model in one dimension. We found this model can accurately characterize a wide variety of patient breathing patterns. This model was used to describe the respiratory motion for 23 patients with peak-to-peak motion greater than 7 mm. The average root mean square error over all patients was less than 1 mm and no patient has an error worse than 1.5 mm. Our model provides a convenient tool to quantify respiratory motion characteristics, such as patterns of frequency changes and amplitude changes, and can be applied to internal or external motion, including internal tumour position, abdominal surface, diaphragm, spirometry and other surrogates.

  3. Evaluation of a New Motion-correction Algorithm Using On-rigid Registration in Respiratory-gated PET/CT Images of Liver Tumors.

    Science.gov (United States)

    Wagatsuma, Kei; Osawa, Tatsufumi; Yokokawa, Naoki; Miwa, Kenta; Oda, Keiichi; Kudo, Yoshiro; Unno, Yasushi; Ito, Kimiteru; Ishii, Kenji

    2016-01-01

    The present study aimed to determine the qualitative and quantitative accuracy of the Q.Freeze algorithm in PET/CT images of liver tumors. A body phantom and hot spheres representing liver tumors contained 5.3 and 21.2 kBq/mL of a solution containing 18 F radioactivity, respectively. The phantoms were moved in the superior-inferior direction at a motion displacement of 20 mm. Conventional respiratory-gated (RG) and Q.Freeze images were sorted into 6, 10, and 13 phase-groups. The SUV ave was calculated from the background of the body phantom, and the SUV max was determined from the hot spheres of the liver tumors. Three patients with four liver tumors were also clinically assessed by whole-body and RG PET. The RG and Q.Freeze images derived from the clinical study were also sorted into 6, 10 and 13 phase-groups. Liver signal-to-noise ratio (SNR) and SUV max were determined from the RG and Q.Freeze clinical images. The SUV ave of Q.Freeze images was the same as those derived from the body phantom using RG. The liver SNR improved with Q.Freeze, and the SUVs max was not overestimated when Q.Freeze was applied in both the phantom and clinical studies. Q.Freeze did not degrade the liver SNR and SUV max even though the phase number was larger. Q.Freeze delivered qualitative and quantitative motion correction than conventional RG imaging even in 10-phase groups.

  4. Investigation of a breathing surrogate prediction algorithm for prospective pulmonary gating

    International Nuclear Information System (INIS)

    White, Benjamin M.; Low, Daniel A.; Zhao Tianyu; Wuenschel, Sara; Lu, Wei; Lamb, James M.; Mutic, Sasa; Bradley, Jeffrey D.; El Naqa, Issam

    2011-01-01

    Purpose: A major challenge of four dimensional computed tomography (4DCT) in treatment planning and delivery has been the lack of respiration amplitude and phase reproducibility during image acquisition. The implementation of a prospective gating algorithm would ensure that images would be acquired only during user-specified breathing phases. This study describes the development and testing of an autoregressive moving average (ARMA) model for human respiratory phase prediction under quiet respiration conditions. Methods: A total of 47 4DCT patient datasets and synchronized respiration records was utilized in this study. Three datasets were used in model development and were removed from further evaluation of the ARMA model. The remaining 44 patient datasets were evaluated with the ARMA model for prediction time steps from 50 to 1000 ms in increments of 50 and 100 ms. Thirty-five of these datasets were further used to provide a comparison between the proposed ARMA model and a commercial algorithm with a prediction time step of 240 ms. Results: The optimal number of parameters for the ARMA model was based on three datasets reserved for model development. Prediction error was found to increase as the prediction time step increased. The minimum prediction time step required for prospective gating was selected to be half of the gantry rotation period. The maximum prediction time step with a conservative 95% confidence criterion was found to be 0.3 s. The ARMA model predicted peak inhalation and peak exhalation phases significantly better than the commercial algorithm. Furthermore, the commercial algorithm had numerous instances of missed breath cycles and falsely predicted breath cycles, while the proposed model did not have these errors. Conclusions: An ARMA model has been successfully applied to predict human respiratory phase occurrence. For a typical CT scanner gantry rotation period of 0.4 s (0.2 s prediction time step), the absolute error was relatively small, 0

  5. Spirometrically gated /sup 133/Xe ventilation imaging and phase analysis for assessment of regional lung function

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Tomio (Kanto Teishin Hospital, Tokyo (Japan))

    1984-10-01

    The purpose of this study is to develop the technique of performing spirometrically gated /sup 133/Xe ventilation imaging and to evaluate its clinical usefulness for the assessment of regional ventilatory function in various lung diseases. Patients rebreathed /sup 133/Xe gas through the system with constant rates signaled by a metronome. The trigger signals from the patients were recorded in a minicomputer for 60 respiratory cycles simultaneously with posterior lung images. Functional images (phase analysis images) indicating phase and amplitude of regional ventilation were constructed by the first harmonic Fourier analysis. Materials included 13 normal volunteers and patients with COPD (24), lung cancer (5), pulmonary embolism (4) and others (20). In normal controls, phase analysis images before respiratory motion correction revealed gradual decrease in amplitude from base to apex with uniform phase distribution. The amplitude and phase distribution after respiratory motion correction became even more uniform. In patients with COPD, phase analysis images showed asymmetrical and irregular amplitude distribution with non-uniform phase distribution. The standard deviation (S.D.) of phase histogram correlated well with FEVsub(1.0)% (r=0.71, p < 0.001) and down slope of flow-volume curve (r=0.55, p < 0.001), and less prominently with %VC (r=0.42, p < 0.01). Mean S.D. in patients with COPD (12.3 +- 6.5 degree, mean+-1 s.d.) was significantly larger than in normal controls (6.3 +- 1.5). Amplitude profile curve analysis revealed 83% sensitivity for the detection of abnormal spirometric respiratory function test. Data aquisition and processing of present method are rapid and easy to perform. The phase analysis of the gated ventilation images should prove useful in the clinical evaluation of patients with uneven ventilation such as COPD.

  6. New gate opening hours

    CERN Multimedia

    GS Department

    2009-01-01

    Please note the new opening hours of the gates as well as the intersites tunnel from the 19 May 2009: GATE A 7h - 19h GATE B 24h/24 GATE C 7h - 9h\t17h - 19h GATE D 8h - 12h\t13h - 16h GATE E 7h - 9h\t17h - 19h Prévessin 24h/24 The intersites tunnel will be opened from 7h30 to 18h non stop. GS-SEM Group Infrastructure and General Services Department

  7. ISAC's Gating-ML 2.0 data exchange standard for gating description.

    Science.gov (United States)

    Spidlen, Josef; Moore, Wayne; Brinkman, Ryan R

    2015-07-01

    The lack of software interoperability with respect to gating has traditionally been a bottleneck preventing the use of multiple analytical tools and reproducibility of flow cytometry data analysis by independent parties. To address this issue, ISAC developed Gating-ML, a computer file format to encode and interchange gates. Gating-ML 1.5 was adopted and published as an ISAC Candidate Recommendation in 2008. Feedback during the probationary period from implementors, including major commercial software companies, instrument vendors, and the wider community, has led to a streamlined Gating-ML 2.0. Gating-ML has been significantly simplified and therefore easier to support by software tools. To aid developers, free, open source reference implementations, compliance tests, and detailed examples are provided to stimulate further commercial adoption. ISAC has approved Gating-ML as a standard ready for deployment in the public domain and encourages its support within the community as it is at a mature stage of development having undergone extensive review and testing, under both theoretical and practical conditions. © 2015 International Society for Advancement of Cytometry.

  8. Multidetector CT evaluation of the postoperative pancreas.

    Science.gov (United States)

    Yamauchi, Fernando I; Ortega, Cinthia D; Blasbalg, Roberto; Rocha, Manoel S; Jukemura, José; Cerri, Giovanni G

    2012-01-01

    Several pancreatic diseases may require surgical treatment, with most of these procedures classified as resection or drainage. Resection procedures, which are usually performed to remove pancreatic tumors, include pancreatoduodenectomy, central pancreatectomy, distal pancreatectomy, and total pancreatectomy. Drainage procedures are usually performed to treat chronic pancreatitis after the failure of medical therapy and include the Puestow and Frey procedures. The type of surgery depends not only on the patient's symptoms and the location of the disease, but also on the expertise of the surgeon. Radiologists should become familiar with these surgical procedures to better understand postoperative changes in anatomic findings. Multidetector computed tomography is the modality of choice for identifying normal findings after surgery, postoperative complications, and tumor recurrence in patients who have undergone pancreatic surgery. RSNA, 2012

  9. Multi-detector computed tomography of acute abdomen

    International Nuclear Information System (INIS)

    Leschka, Sebastian; Alkadhi, Hatem; Wildermuth, Simon; Marincek, Borut; University Hospital of Zurich

    2005-01-01

    Acute abdominal pain is one of the most common causes for referrals to the emergency department. The sudden onset of severe abdominal pain characterising the ''acute abdomen'' requires rapid and accurate identification of a potentially life-threatening abdominal pathology to provide a timely referral to the appropriate physician. While the physical examination and laboratory investigations are often non-specific, computed tomography (CT) has evolved as the first-line imaging modality in patients with an acute abdomen. Because the new multi-detector CT (MDCT) scanner generations provide increased speed, greater volume coverage and thinner slices, the acceptance of CT for abdominal imaging has increased rapidly. The goal of this article is to discuss the role of MDCT in the diagnostic work-up of acute abdominal pain. (orig.)

  10. Multidetector computed tomography of the renal arteries in vascular emergencies

    International Nuclear Information System (INIS)

    Regine, Giovanni; Stasolla, Alessandro; Miele, Vittorio

    2007-01-01

    Multidetector computed tomography (MDCT) has drastically changed the diagnostic imaging protocol in both traumatic and non-traumatic vascular emergencies, replacing almost completely the traditional primary role of catheter angiography. MDCT is a well-established tool for the elective evaluation of stenoses, malformations, and dysplasias in the settings of renovascular hypertension, but probably less used in the settings of acute traumatic and non-traumatic clinical situations. The aim of this review is to define the role of MDCT in renal arteries emergencies

  11. Automated quantitative coronary computed tomography correlates of myocardial ischaemia on gated myocardial perfusion SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Graaf, Michiel A. de; Boogers, Mark J.; Veltman, Caroline E. [Leiden University Medical Center, Department of Cardiology, Leiden (Netherlands); The Interuniversity Cardiology Institute of The Netherlands, Utrecht (Netherlands); El-Naggar, Heba M.; Bax, Jeroen J.; Delgado, Victoria [Leiden University Medical Center, Department of Cardiology, Leiden (Netherlands); Broersen, Alexander; Kitslaar, Pieter H.; Dijkstra, Jouke [Leiden University Medical Center, Department of Radiology, Division of Image Processing, Leiden (Netherlands); Kroft, Lucia J. [Leiden University Medical Center, Department of Radiology, Leiden (Netherlands); Younis, Imad Al [Leiden University Medical Center, Department of Nuclear Medicine, Leiden (Netherlands); Reiber, Johan H. [Leiden University Medical Center, Department of Radiology, Division of Image Processing, Leiden (Netherlands); Medis medical imaging systems B.V., Leiden (Netherlands); Scholte, Arthur J. [Leiden University Medical Center, Department of Cardiology, Leiden (Netherlands)

    2013-08-15

    Automated software tools have permitted more comprehensive, robust and reproducible quantification of coronary stenosis, plaque burden and plaque location of coronary computed tomography angiography (CTA) data. The association between these quantitative CTA (QCT) parameters and the presence of myocardial ischaemia has not been explored. The aim of the present investigation was to evaluate the association between QCT parameters of coronary artery lesions and the presence of myocardial ischaemia on gated myocardial perfusion single-photon emission CT (SPECT). Included in the study were 40 patients (mean age 58.2 {+-} 10.9 years, 27 men) with known or suspected coronary artery disease (CAD) who had undergone multidetector row CTA and gated myocardial perfusion SPECT within 6 months. From the CTA datasets, vessel-based and lesion-based visual analyses were performed. Consecutively, lesion-based QCT was performed to assess plaque length, plaque burden, percentage lumen area stenosis and remodelling index. Subsequently, the presence of myocardial ischaemia was assessed using the summed difference score (SDS {>=}2) on gated myocardial perfusion SPECT. Myocardial ischaemia was seen in 25 patients (62.5 %) in 37 vascular territories. Quantitatively assessed significant stenosis and quantitatively assessed lesion length were independently associated with myocardial ischaemia (OR 7.72, 95 % CI 2.41-24.7, p < 0.001, and OR 1.07, 95 % CI 1.00-1.45, p = 0.032, respectively) after correcting for clinical variables and visually assessed significant stenosis. The addition of quantitatively assessed significant stenosis ({chi} {sup 2} = 20.7) and lesion length ({chi} {sup 2} = 26.0) to the clinical variables and the visual assessment ({chi} {sup 2} = 5.9) had incremental value in the association with myocardial ischaemia. Coronary lesion length and quantitatively assessed significant stenosis were independently associated with myocardial ischaemia. Both quantitative parameters have

  12. Preoperative staging of esophageal carcinoma with multidetector CT and virtual endoscopy

    International Nuclear Information System (INIS)

    Onbas, Omer; Eroglu, Atilla; Kantarci, Mecit; Polat, Pinar; Alper, Fatih; Karaoglanoglu, Nurettin; Okur, Adnan

    2006-01-01

    Purpose: The aim of this study was to assess the accuracy of multidetector computed tomography (MDCT), including virtual endoscopy (VE) for detection, precise localization, preoperative evaluation and staging of esophageal cancer (EC) by comparison with surgical and histopathological findings. Materials and methods: Between September 2003 and April 2005, 44 patients with histologically proven EC underwent MDCT and VE. Among 44 patients, the findings were confirmed in 24 at surgery. The accuracy of three-dimensional MDCT for detection, localization, and staging of EC was determined, and compared with surgical finding and histopathology. Results: The overall accuracy of three-dimensional multidetector row CT for detection of EC was 100% (24/24). MDCT staging was correct in 20 patients (83.3%). The T parameter was correctly assessed in 22 (91.7%) cases (understaged in 1 and overstaged in 1). The N parameter was correctly evaluated in 20 (83.4%) patients (understaged in 2 and overstaged in 2). The overall accuracy of VE for the morphologic classification of EC was 81.5%. Conclusions: Three-dimensional MDCT, along with VE is a promising method for preoperative evaluation and staging of EC. Although accuracy in N staging remains low in comparison to PET, it provides a larger amount of diagnostic and staging information

  13. Evaluation of the geometric accuracy of surrogate-based gated VMAT using intrafraction kilovoltage x-ray images

    International Nuclear Information System (INIS)

    Li Ruijiang; Mok, Edward; Han, Bin; Koong, Albert; Xing Lei

    2012-01-01

    Purpose: To evaluate the geometric accuracy of beam targeting in external surrogate-based gated volumetric modulated arc therapy (VMAT) using kilovoltage (kV) x-ray images acquired during dose delivery. Methods: Gated VMAT treatments were delivered using a Varian TrueBeam STx Linac for both physical phantoms and patients. Multiple gold fiducial markers were implanted near the target. The reference position was created for each implanted marker, representing its correct position at the gating threshold. The gating signal was generated from the RPM system. During the treatment, kV images were acquired immediately before MV beam-on at every breathing cycle, using the on-board imaging system. All implanted markers were detected and their 3D positions were estimated using in-house developed software. The positioning error of a marker is defined as the distance of the marker from its reference position for each frame of the images. The overall error of the system is defined as the average over all markers. For the phantom study, both sinusoidal motion (1D and 3D) and real human respiratory motion was simulated for the target and surrogate. In the baseline case, the two motions were synchronized for the first treatment fraction. To assess the effects of surrogate-target correlation on the geometric accuracy, a phase shift of 5% and 10% between the two motions was introduced. For the patient study, intrafraction kV images of five stereotactic body radiotherapy (SBRT) patients were acquired for one or two fractions. Results: For the phantom study, a high geometric accuracy was achieved in the baseline case (average error: 0.8 mm in the superior-inferior or SI direction). However, the treatment delivery is prone to geometric errors if changes in the target-surrogate relation occur during the treatment: the average error was increased to 2.3 and 4.7 mm for the phase shift of 5% and 10%, respectively. Results obtained with real human respiratory curves show a similar trend

  14. Molecular mechanism of voltage sensing in voltage-gated proton channels

    Science.gov (United States)

    Rebolledo, Santiago; Perez, Marta E.

    2013-01-01

    Voltage-gated proton (Hv) channels play an essential role in phagocytic cells by generating a hyperpolarizing proton current that electrically compensates for the depolarizing current generated by the NADPH oxidase during the respiratory burst, thereby ensuring a sustained production of reactive oxygen species by the NADPH oxidase in phagocytes to neutralize engulfed bacteria. Despite the importance of the voltage-dependent Hv current, it is at present unclear which residues in Hv channels are responsible for the voltage activation. Here we show that individual neutralizations of three charged residues in the fourth transmembrane domain, S4, all reduce the voltage dependence of activation. In addition, we show that the middle S4 charged residue moves from a position accessible from the cytosolic solution to a position accessible from the extracellular solution, suggesting that this residue moves across most of the membrane electric field during voltage activation of Hv channels. Our results show for the first time that the charge movement of these three S4 charges accounts for almost all of the measured gating charge in Hv channels. PMID:23401575

  15. Diagnostic ability of Barrett's index to detect dysthyroid optic neuropathy using multidetector computed tomography

    International Nuclear Information System (INIS)

    Monteiro, Mario L.R.; Goncalves, Allan C.P.; Silva, Carla T.M.; Moura, Janete P.; Ribeiro, Carolina S.; Gebrim, Eloisa M.M.S.; Universidade de Sao Paulo; Universidade de Sao Paulo

    2008-01-01

    Objectives: The objective of this study was to evaluate the ability of a muscular index (Barrett's Index), calculated with multidetector computed tomography, to detect dysthyroid optic neuropathy in patients with Graves' orbitopathy. Methods: Thirty-six patients with Graves' orbitopathy were prospectively studied and submitted to neuro-ophthalmic evaluation and multidetector computed tomography scans of the orbits. Orbits were divided into two groups: those with and without dysthyroid optic neuropathy. Barrett's index was calculated as the percentage of the orbit occupied by muscles. Sensitivity and specificity were determined for several index values. Results: Sixty-four orbits (19 with and 45 without dysthyroid optic neuropathy) met the inclusion criteria for the study. The mean Barrett's index values (±SD) were 64.47% ± 6.06% and 49.44% ± 10.94% in the groups with and without dysthyroid optic neuropathy, respectively (p 60% should be carefully examined and followed for the development of dysthyroid optic neuropathy. (author)

  16. Diagnostic ability of barrett's index to detect dysthyroid optic neuropathy using multidetector computed tomography

    Directory of Open Access Journals (Sweden)

    Mário L. R. Monteiro

    2008-01-01

    Full Text Available OBJECTIVES: The objective of this study was to evaluate the ability of a muscular index (Barrett's Index, calculated with multidetector computed tomography, to detect dysthyroid optic neuropathy in patients with Graves' orbitopathy. METHODS: Thirty-six patients with Graves' orbitopathy were prospectively studied and submitted to neuro-ophthalmic evaluation and multidetector computed tomography scans of the orbits. Orbits were divided into two groups: those with and without dysthyroid optic neuropathy. Barrett's index was calculated as the percentage of the orbit occupied by muscles. Sensitivity and specificity were determined for several index values. RESULTS: Sixty-four orbits (19 with and 45 without dysthyroid optic neuropathy met the inclusion criteria for the study. The mean Barrett's index values (± SD were 64.47% ± 6.06% and 49.44% ± 10.94%in the groups with and without dysthyroid optic neuropathy, respectively (p60% should be carefully examined and followed for the development of dysthyroid optic neuropathy.

  17. Multiplanar and two-dimensional imaging of central airway stenting with multidetector computed tomography

    Directory of Open Access Journals (Sweden)

    Ozgul Mehmet

    2012-08-01

    Full Text Available Abstract Background Multidetector computed tomography (MDCT provides guidance for primary screening of the central airways. The aim of our study was assessing the contribution of multidetector computed tomography- two dimensional reconstruction in the management of patients with tracheobronchial stenosis prior to the procedure and during a short follow up period of 3 months after the endobronchial treatment. Methods This is a retrospective study with data collected from an electronic database and from the medical records. Patients evaluated with MDCT and who had undergone a stenting procedure were included. A Philips RSGDT 07605 model MDCT was used, and slice thickness, 3 mm; overlap, 1.5 mm; matrix, 512x512; mass, 90 and kV, 120 were evaluated. The diameters of the airways 10 mm proximal and 10 mm distal to the obstruction were measured and the stent diameter (D was determined from the average between D upper and D lower. Results Fifty-six patients, 14 (25% women and 42 (75% men, mean age 55.3 ± 13.2 years (range: 16-79 years, were assessed by MDCT and then treated with placement of an endobronchial stent. A computed tomography review was made with 6 detector Philips RSGDT 07605 multidetector computed tomography device. Endobronchial therapy was provided for the patients with endoluminal lesions. Stents were placed into the area of stenosis in patients with external compression after dilatation and debulking procedures had been carried out. In one patient the migration of a stent was detected during the follow up period by using MDCT. Conclusions MDCT helps to define stent size, length and type in patients who are suitable for endobronchial stinting. This is a non-invasive, reliable method that helps decisions about optimal stent size and position, thus reducing complications.

  18. Quantitation of respiratory motion during 4D-PET/CT acquisition

    International Nuclear Information System (INIS)

    Nehmeh, S.A.; Erdi, Y.E.; Pan, T.; Yorke, E.; Mageras, G.S.; Rosenzweig, K.E.; Schoder, H.; Mostafavi, H.; Squire, O.; Pevsner, A.; Larson, S.M.; Humm, J.L.

    2004-01-01

    We report on the variability of the respiratory motion during 4D-PET/CT acquisition. The respiratory motion for five lung cancer patients was monitored by tracking external markers placed on the abdomen. CT data were acquired over an entire respiratory cycle at each couch position. The x-ray tube status was recorded by the tracking system, for retrospective sorting of the CT data as a function of respiration phase. Each respiratory cycle was sampled in ten equal bins. 4D-PET data were acquired in gated mode, where each breathing cycle was divided into ten 500 ms bins. For both CT and PET acquisition, patients received audio prompting to regularize breathing. The 4D-CT and 4D-PET data were then correlated according to their respiratory phases. The respiratory periods, and average amplitude within each phase bin, acquired in both modality sessions were then analyzed. The average respiratory motion period during 4D-CT was within 18% from that in the 4D-PET sessions. This would reflect up to 1.8% fluctuation in the duration of each 4D-CT bin. This small uncertainty enabled good correlation between CT and PET data, on a phase-to-phase basis. Comparison of the average-amplitude within the respiration trace, between 4D-CT and 4D- PET, on a bin-by-bin basis show a maximum deviation of ∼15%. This study has proved the feasibility of performing 4D-PET/CT acquisition. Respiratory motion was in most cases consistent between PET and CT sessions, thereby improving both the attenuation correction of PET images, and co-registration of PET and CT images. On the other hand, in two patients, there was an increased partial irregularity in their breathing motion, which would prevent accurately correlating the corresponding PET and CT images

  19. Respiration-correlated spiral CT: A method of measuring respiratory-induced anatomic motion for radiation treatment planning

    International Nuclear Information System (INIS)

    Ford, E.C.; Mageras, G.S.; Yorke, E.; Ling, C.C.

    2003-01-01

    We describe a method for generating CT images at multiple respiratory phases with a single spiral CT scan, referred to as respiratory-correlated spiral CT (RCCT). RCCT relies on a respiration wave form supplied by an external patient monitor. During acquisition this wave form is recorded along with the initiation time of the CT scan, so as to 'time stamp' each reconstructed slice with the phase of the respiratory cycle. By selecting the appropriate slices, a full CT image set is generated at several phases, typically 7-11 per cycle. The CT parameters are chosen to optimize the temporal resolution while minimizing the spatial gap between slices at successive respiratory cycles. Using a pitch of 0.5, a gantry rotation period of 1.5 s, and a 180 degree sign reconstruction algorithm results in ∼5 mm slice spacing at a given phase for typical respiration periods, and a respiratory motion within each slice that is acceptably small, particularly near end expiration or end inspiration where gated radiotherapy is to occur. We have performed validation measurements on a phantom with a moving sphere designed to simulate respiration-induced tumor motion. RCCT scans of the phantom at respiratory periods of 4, 5, and 6 s show good agreement of the sphere's motion with that observed under fluoroscopic imaging. The positional deviations in the sphere's centroid between RCCT and fluoroscopy are 1.1±0.9 mm in the transaxial direction (average over all scans at all phases ±1 s.d.) and 1.2±1.0 mm in the longitudinal direction. Reconstructed volumes match those expected on the basis of stationary-phantom scans to within 5% in all cases. The surface distortions of the reconstructed sphere, as quantified by deviations from a mathematical reference sphere, are similar to those from a stationary phantom scan and are correlated with the speed of the phantom. A RCCT scan of the phantom undergoing irregular motion, demonstrates that successful reconstruction can be achieved even with

  20. The normal anatomy and variations of the bronchial arteries: evaluation with multidetector computed tomography.

    Science.gov (United States)

    Yener, Özlem; Türkvatan, Aysel; Yüce, Gökhan; Yener, Ali Ümit

    2015-02-01

    In this study, we aimed to reveal the normal anatomy and variations of the bronchial arterial system and to determine the sex distribution of these variations by retrospectively reviewing the images of patients who underwent thoracal multidetector computed tomographic angiography for various reasons. Multidetector computed tomographic images of a total of 208 patients (151 men; mean age, 59 years) were retrospectively reviewed to assess the normal anatomy and variations of the bronchial arterial system. A total of 531 bronchial arteries (median, 3; minimum, 1; maximum, 5; mean, 2.5) were detected. The number (mean diameter) of the right bronchial arteries were higher than the left bronchial arteries (290 [1.43 mm] and 241 [1.26 mm], respectively; P arteries were higher with men than with women (2.58 [1.45 mm] and 2.47 [1.32 mm], respectively; P artery, and, secondarily (13.46%), the combination of 2 right (1 intercostal-bronchial trunk and 1 bronchial artery) and 1 left bronchial arteries. Seventy-eight ectopic bronchial arteries were detected in 59 cases (28.3%). They most commonly originated from the aortic arch (37.2%), the descending aorta below the level of T6 (35.9%), or the aortic branches (16.7%). The number of right ectopic bronchial arteries was significantly higher than the left ectopic bronchial arteries (50 [64%] vs 28 [36%]; P arteries was statistically higher with men versus women (45 [29.8%] vs 14 [24.6%]; P arteries can vary substantially among individuals. Multidetector computed tomographic angiography enables a detailed road map of the bronchial arterial system to interventional radiologists and thoracic surgeons. Copyright © 2015 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  1. Long-term internal thoracic artery bypass graft patency and geometry assessed by multidetector computed tomography

    DEFF Research Database (Denmark)

    Zacho, Mette; Damgaard, Sune; Lilleoer, Nikolaj Thomas

    2012-01-01

    The left internal thoracic artery (LITA) undergoes vascular remodelling when used for coronary artery bypass grafting. In this study we tested the hypothesis that the extent of the LITA remodelling late after coronary artery bypass grafting assessed by multidetector computed tomography is related...

  2. Field Programmable Gate Array (FPGA Respiratory Monitoring System Using a Flow Microsensor and an Accelerometer

    Directory of Open Access Journals (Sweden)

    Mellal Idir

    2017-04-01

    Full Text Available This paper describes a non-invasive system for respiratory monitoring using a Micro Electro Mechanical Systems (MEMS flow sensor and an IMU (Inertial Measurement Unit accelerometer. The designed system is intended to be wearable and used in a hospital or at home to assist people with respiratory disorders. To ensure the accuracy of our system, we proposed a calibration method based on ANN (Artificial Neural Network to compensate the temperature drift of the silicon flow sensor. The sigmoid activation functions used in the ANN model were computed with the CORDIC (COordinate Rotation DIgital Computer algorithm. This algorithm was also used to estimate the tilt angle in body position. The design was implemented on reconfigurable platform FPGA.

  3. Gate current for p+-poly PMOS devices under gate injection conditions

    NARCIS (Netherlands)

    Hof, A.J.; Holleman, J.; Woerlee, P.H.

    2001-01-01

    In current CMOS processing both n+-poly and p+-poly gates are used. The I-V –relationship and reliability of n+-poly devices are widely studied and well understood. Gate currents and reliability for p+-poly PMOS devices under gate injection conditions are not well understood. In this paper, the

  4. MO-F-CAMPUS-J-02: Commissioning of Radiofrequency Tracking for Gated SBRT of the Liver Using Novel Motion System

    International Nuclear Information System (INIS)

    James, J; Cetnar, A; Nguyen, V; Wang, B

    2015-01-01

    Purpose: Tracking soft tissue targets has recently been approved as a new application of the Calypso radiofrequency tracking system allowing for gated treatment of the liver based on the motion of the target volume itself. As part of the commissioning process, an end-to-end test was performed using a 3D diode array and 6D motion platform to verify the dosimetric accuracy and establish the workflow of gated SBRT treatment of the liver using Calypso. Methods: A 4DCT scan of the ScandiDos Delta4 phantom was acquired using the HexaMotion motion platform to simulate realistic breathing motion. A VMAT plan was optimized on the end of inspiration phase of the 4DCT scan and delivered to the Delta4 phantom using the Varian TrueBeam. The treatment beam was gated by Calypso to deliver dose at the end of inspiration. The expected dose was compared to the delivered dose using gamma analysis. In addition, gating limits were investigated to determine how large the gating range can be while still maintaining dosimetric accuracy. Results: The 3%/3mm and 2%/2mm gamma pass rate for the gated treatment delivery was 100% and 98.4%, respectively. When increasing the gating limits beyond the known extent of planned motion from the 4DCT, the gamma pass rates decreased as expected. The 3%/3mm gamma pass rate for a 1, 2, and 3mm increase in gating limits were measured to be 96.0%, 92.7%, and 78.8%, respectively. Conclusion: Radiofrequency tracking was shown to be an effective way to provide gated SBRT treatment of the liver. Baseline gating limits should be determined by measuring the extent of target motion during the respiratory phases used for planning. We recommend adding 1mm to the baseline limits to provide the proper balance between treatment efficiency and dosimetric accuracy

  5. Multiple Independent Gate FETs: How Many Gates Do We Need?

    OpenAIRE

    Amarù, Luca; Hills, Gage; Gaillardon, Pierre-Emmanuel; Mitra, Subhasish; De Micheli, Giovanni

    2015-01-01

    Multiple Independent Gate Field Effect Transistors (MIGFETs) are expected to push FET technology further into the semiconductor roadmap. In a MIGFET, supplementary gates either provide (i) enhanced conduction properties or (ii) more intelligent switching functions. In general, each additional gate also introduces a side implementation cost. To enable more efficient digital systems, MIGFETs must leverage their expressive power to realize complex logic circuits with few physical resources. Rese...

  6. Transparently wrap-gated semiconductor nanowire arrays for studies of gate-controlled photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Nylund, Gustav; Storm, Kristian; Torstensson, Henrik; Wallentin, Jesper; Borgström, Magnus T.; Hessman, Dan; Samuelson, Lars [Solid State Physics, Nanometer Structure Consortium, Lund University, Box 118, S-221 00 Lund (Sweden)

    2013-12-04

    We present a technique to measure gate-controlled photoluminescence (PL) on arrays of semiconductor nanowire (NW) capacitors using a transparent film of Indium-Tin-Oxide (ITO) wrapping around the nanowires as the gate electrode. By tuning the wrap-gate voltage, it is possible to increase the PL peak intensity of an array of undoped InP NWs by more than an order of magnitude. The fine structure of the PL spectrum reveals three subpeaks whose relative peak intensities change with gate voltage. We interpret this as gate-controlled state-filling of luminescing quantum dot segments formed by zincblende stacking faults in the mainly wurtzite NW crystal structure.

  7. Dual-Gate p-GaN Gate High Electron Mobility Transistors for Steep Subthreshold Slope.

    Science.gov (United States)

    Bae, Jong-Ho; Lee, Jong-Ho

    2016-05-01

    A steep subthreshold slope characteristic is achieved through p-GaN gate HEMT with dual-gate structure. Obtained subthreshold slope is less than 120 μV/dec. Based on the measured and simulated data obtained from single-gate device, breakdown of parasitic floating-base bipolar transistor and floating gate charged with holes are responsible to increase abruptly in drain current. In the dual-gate device, on-current degrades with high temperature but subthreshold slope is not changed. To observe the switching speed of dual-gate device and transient response of drain current are measured. According to the transient responses of drain current, switching speed of the dual-gate device is about 10(-5) sec.

  8. Multidetector CT in children: current concepts and dose reduction strategies

    Energy Technology Data Exchange (ETDEWEB)

    Nievelstein, Rutger A.J.; Dam, Ingrid M. van [University Medical Centre Utrecht, Department of Pediatric Radiology, Wilhelmina Children' s Hospital, E01.132, P.O. Box 85500, Utrecht (Netherlands); Molen, Aart J. van der [Leiden University Medical Centre, Department of Radiology, C-2S, Leiden (Netherlands)

    2010-08-15

    The recent technical development of multidetector CT (MDCT) has contributed to a substantial increase in its diagnostic applications and accuracy in children. A major drawback of MDCT is the use of ionising radiation with the risk of inducing secondary cancer. Therefore, justification and optimisation of paediatric MDCT is of great importance in order to minimise these risks (''as low as reasonably achievable'' principle). This review will focus on all technical and non-technical aspects relevant for paediatric MDCT optimisation and includes guidelines for radiation dose level-based CT protocols. (orig.)

  9. Multidetector CT in children: current concepts and dose reduction strategies

    International Nuclear Information System (INIS)

    Nievelstein, Rutger A.J.; Dam, Ingrid M. van; Molen, Aart J. van der

    2010-01-01

    The recent technical development of multidetector CT (MDCT) has contributed to a substantial increase in its diagnostic applications and accuracy in children. A major drawback of MDCT is the use of ionising radiation with the risk of inducing secondary cancer. Therefore, justification and optimisation of paediatric MDCT is of great importance in order to minimise these risks (''as low as reasonably achievable'' principle). This review will focus on all technical and non-technical aspects relevant for paediatric MDCT optimisation and includes guidelines for radiation dose level-based CT protocols. (orig.)

  10. Top-gate pentacene-based organic field-effect transistor with amorphous rubrene gate insulator

    Science.gov (United States)

    Hiroki, Mizuha; Maeda, Yasutaka; Ohmi, Shun-ichiro

    2018-02-01

    The scaling of organic field-effect transistors (OFETs) is necessary for high-density integration and for this, OFETs with a top-gate configuration are required. There have been several reports of damageless lithography processes for organic semiconductor or insulator layers. However, it is still difficult to fabricate scaled OFETs with a top-gate configuration. In this study, the lift-off process and the device characteristics of the OFETs with a top-gate configuration utilizing an amorphous (α) rubrene gate insulator were investigated. We have confirmed that α-rubrene shows an insulating property, and its extracted linear mobility was 2.5 × 10-2 cm2/(V·s). The gate length and width were 10 and 60 µm, respectively. From these results, the OFET with a top-gate configuration utilizing an α-rubrene gate insulator is promising for the high-density integration of scaled OFETs.

  11. Analytical drain current formulation for gate dielectric engineered dual material gate-gate all around-tunneling field effect transistor

    Science.gov (United States)

    Madan, Jaya; Gupta, R. S.; Chaujar, Rishu

    2015-09-01

    In this work, an analytical drain current model for gate dielectric engineered (hetero dielectric)-dual material gate-gate all around tunnel field effect transistor (HD-DMG-GAA-TFET) has been developed. Parabolic approximation has been used to solve the two-dimensional (2D) Poisson equation with appropriate boundary conditions and continuity equations to evaluate analytical expressions for surface potential, electric field, tunneling barrier width and drain current. Further, the analog performance of the device is studied for three high-k dielectrics (Si3N4, HfO2, and ZrO2), and it has been investigated that the problem of lower ION, can be overcome by using the hetero-gate architecture. Moreover, the impact of scaling the gate oxide thickness and bias variations has also been studied. The HD-DMG-GAA-TFET shows an enhanced ION of the order of 10-4 A. The effectiveness of the proposed model is validated by comparing it with ATLAS device simulations.

  12. A gate drive circuit for gate-turn-off (GTO) devices in series stack

    International Nuclear Information System (INIS)

    Despe, O.

    1999-01-01

    A gate-turn-off (GTO) switch is under development at the Advanced Photon Source as a replacement for a thyratron switch in high power pulsed application. The high voltage in the application requires multiple GTOs connected in series. One component that is critical to the success of GTO operation is the gate drive circuit. The gate drive circuit has to provide fast high-current pulses to the GTO gate for fast turn-on and turn-off. It also has to be able to operate while floating at high voltage. This paper describes a gate drive circuit that meets these requirements

  13. Multidetector computed tomography angiography of the renal arteries: normal anatomy and its variations

    Directory of Open Access Journals (Sweden)

    Carlos Fernando de Mello Júnior

    2016-06-01

    Full Text Available Abstract Conventional angiography is still considered the gold standard for the study of the anatomy and of vascular diseases of the abdomen. However, the advent of multidetector computed tomography and techniques of digital image reconstruction has provided an alternative means of performing angiography, without the risks inherent to invasive angiographic examinations. Therefore, within the field of radiology, there is an ever-increasing demand for deeper knowledge of the anatomy of the regional vasculature and its variations. Variations in the renal vascular system are relatively prevalent in the venous and arterial vessels. For various conditions in which surgical planning is crucial to the success of the procedure, knowledge of this topic is important. The aim of this study was to familiarize the general radiologist with variations in the renal vascular system. To that end, we prepared a pictorial essay comprising multidetector computed tomography images obtained in a series of cases. We show patterns representative of the most common anatomical variations in the arterial blood supply to the kidneys, calling attention to the nomenclature, as well as to the clinical and surgical implications of such variations.

  14. Multidetector computed tomography angiography of the renal arteries: normal anatomy and its variations

    International Nuclear Information System (INIS)

    Mello Junior, Carlos Fernando de; Araujo Neto, Severino Aires; Carvalho Junior, Arlindo Monteiro de; Negromonte, Gustavo Ramalho Pessoa; Oliveira, Carollyne Dantas de; Reboucas, Rafael Batista

    2016-01-01

    Conventional angiography is still considered the gold standard for the study of the anatomy and of vascular diseases of the abdomen. However, the advent of multidetector computed tomography and techniques of digital image reconstruction has provided an alternative means of performing angiography, without the risks inherent to invasive angiographic examinations. Therefore, within the field of radiology, there is an ever-increasing demand for deeper knowledge of the anatomy of the regional vasculature and its variations. Variations in the renal vascular system are relatively prevalent in the venous and arterial vessels. For various conditions in which surgical planning is crucial to the success of the procedure, knowledge of this topic is important. The aim of this study was to familiarize the general radiologist with variations in the renal vascular system. To that end, we prepared a pictorial essay comprising multidetector computed tomography images obtained in a series of cases. We show patterns representative of the most common anatomical variations in the arterial blood supply to the kidneys, calling attention to the nomenclature, as well as to the clinical and surgical implications of such variations. (author)

  15. Multidetector computed tomography angiography of the renal arteries: normal anatomy and its variations

    Energy Technology Data Exchange (ETDEWEB)

    Mello Junior, Carlos Fernando de; Araujo Neto, Severino Aires; Carvalho Junior, Arlindo Monteiro de; Negromonte, Gustavo Ramalho Pessoa; Oliveira, Carollyne Dantas de [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil); Reboucas, Rafael Batista, E-mail: severinoaires@hotmail.com [Faculdade de Ciencias Medicas da Paraiba, Joao Pessoa, PB (Brazil)

    2016-05-15

    Conventional angiography is still considered the gold standard for the study of the anatomy and of vascular diseases of the abdomen. However, the advent of multidetector computed tomography and techniques of digital image reconstruction has provided an alternative means of performing angiography, without the risks inherent to invasive angiographic examinations. Therefore, within the field of radiology, there is an ever-increasing demand for deeper knowledge of the anatomy of the regional vasculature and its variations. Variations in the renal vascular system are relatively prevalent in the venous and arterial vessels. For various conditions in which surgical planning is crucial to the success of the procedure, knowledge of this topic is important. The aim of this study was to familiarize the general radiologist with variations in the renal vascular system. To that end, we prepared a pictorial essay comprising multidetector computed tomography images obtained in a series of cases. We show patterns representative of the most common anatomical variations in the arterial blood supply to the kidneys, calling attention to the nomenclature, as well as to the clinical and surgical implications of such variations. (author)

  16. Low-power DRAM-compatible Replacement Gate High-k/Metal Gate Stacks

    Science.gov (United States)

    Ritzenthaler, R.; Schram, T.; Bury, E.; Spessot, A.; Caillat, C.; Srividya, V.; Sebaai, F.; Mitard, J.; Ragnarsson, L.-Å.; Groeseneken, G.; Horiguchi, N.; Fazan, P.; Thean, A.

    2013-06-01

    In this work, the possibility of integration of High-k/Metal Gate (HKMG), Replacement Metal Gate (RMG) gate stacks for low power DRAM compatible transistors is studied. First, it is shown that RMG gate stacks used for Logic applications need to be seriously reconsidered, because of the additional anneal(s) needed in a DRAM process. New solutions are therefore developed. A PMOS stack HfO2/TiN with TiN deposited in three times combined with Work Function metal oxidations is demonstrated, featuring a very good Work Function of 4.95 eV. On the other hand, the NMOS side is shown to be a thornier problem to solve: a new solution based on the use of oxidized Ta as a diffusion barrier is proposed, and a HfO2/TiN/TaOX/TiAl/TiN/TiN gate stack featuring an aggressive Work Function of 4.35 eV (allowing a Work Function separation of 600 mV between NMOS and PMOS) is demonstrated. This work paves the way toward the integration of gate-last options for DRAM periphery transistors.

  17. SU-E-J-67: Evaluation of Breathing Patterns for Respiratory-Gated Radiation Therapy Using Respiration Regularity Index

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, K; Lee, M; Kang, S; Yoon, J; Park, S; Hwang, T; Kim, H; Kim, K; Han, T; Bae, H [Hallym University College of Medicine, Anyang (Korea, Republic of)

    2014-06-01

    Purpose: Despite the importance of accurately estimating the respiration regularity of a patient in motion compensation treatment, an effective and simply applicable method has rarely been reported. The authors propose a simple respiration regularity index based on parameters derived from a correspondingly simplified respiration model. Methods: In order to simplify a patient's breathing pattern while preserving the data's intrinsic properties, we defined a respiration model as a power of cosine form with a baseline drift. According to this respiration formula, breathing-pattern fluctuation could be explained using four factors: sample standard deviation of respiration period, sample standard deviation of amplitude and the results of simple regression of the baseline drift (slope and standard deviation of residuals of a respiration signal. Overall irregularity (δ) was defined as a Euclidean norm of newly derived variable using principal component analysis (PCA) for the four fluctuation parameters. Finally, the proposed respiration regularity index was defined as ρ=ln(1+(1/ δ))/2, a higher ρ indicating a more regular breathing pattern. Subsequently, we applied it to simulated and clinical respiration signals from real-time position management (RPM; Varian Medical Systems, Palo Alto, CA) and investigated respiration regularity. Moreover, correlations between the regularity of the first session and the remaining fractions were investigated using Pearson's correlation coefficient. Results: The respiration regularity was determined based on ρ; patients with ρ<0.3 showed worse regularity than the others, whereas ρ>0.7 was suitable for respiratory-gated radiation therapy (RGRT). Fluctuations in breathing cycle and amplitude were especially determinative of ρ. If the respiration regularity of a patient's first session was known, it could be estimated through subsequent sessions. Conclusions: Respiration regularity could be objectively determined

  18. SU-E-J-67: Evaluation of Breathing Patterns for Respiratory-Gated Radiation Therapy Using Respiration Regularity Index

    International Nuclear Information System (INIS)

    Cheong, K; Lee, M; Kang, S; Yoon, J; Park, S; Hwang, T; Kim, H; Kim, K; Han, T; Bae, H

    2014-01-01

    Purpose: Despite the importance of accurately estimating the respiration regularity of a patient in motion compensation treatment, an effective and simply applicable method has rarely been reported. The authors propose a simple respiration regularity index based on parameters derived from a correspondingly simplified respiration model. Methods: In order to simplify a patient's breathing pattern while preserving the data's intrinsic properties, we defined a respiration model as a power of cosine form with a baseline drift. According to this respiration formula, breathing-pattern fluctuation could be explained using four factors: sample standard deviation of respiration period, sample standard deviation of amplitude and the results of simple regression of the baseline drift (slope and standard deviation of residuals of a respiration signal. Overall irregularity (δ) was defined as a Euclidean norm of newly derived variable using principal component analysis (PCA) for the four fluctuation parameters. Finally, the proposed respiration regularity index was defined as ρ=ln(1+(1/ δ))/2, a higher ρ indicating a more regular breathing pattern. Subsequently, we applied it to simulated and clinical respiration signals from real-time position management (RPM; Varian Medical Systems, Palo Alto, CA) and investigated respiration regularity. Moreover, correlations between the regularity of the first session and the remaining fractions were investigated using Pearson's correlation coefficient. Results: The respiration regularity was determined based on ρ; patients with ρ 0.7 was suitable for respiratory-gated radiation therapy (RGRT). Fluctuations in breathing cycle and amplitude were especially determinative of ρ. If the respiration regularity of a patient's first session was known, it could be estimated through subsequent sessions. Conclusions: Respiration regularity could be objectively determined using a respiration regularity index, ρ. Such single-index testing of

  19. Volume and dimensions of angiographically normal coronary arteries assessed by multidetector computed tomography

    DEFF Research Database (Denmark)

    Sørensen, Samuel Kiil; Kühl, Jørgen Tobias; Fuchs, Andreas

    2017-01-01

    BACKGROUND: The objective of this study was to determine normal values for coronary artery volume (CAV) and individual vasculature and segment dimensions. METHODS: We examined 200 healthy volunteers with an Agatston score of 0 and a normal, high quality coronary CTA. Using 320 slice multidetector...... administration and left ventricular mass. The respective contribution of the left and right coronary vascularture is influenced by coronary dominance....

  20. Setting graphic software for data examination of multidetector used in heavy ions physic

    International Nuclear Information System (INIS)

    Le Flecher, C.

    1990-01-01

    In this work, the first chapter presents both the multidetectors of the vacuum chamber NAUTILUS, from a geometrical and parametrical point of view and the manual analysis phase. The second part deals with the main notions of the language Graphical Kernel System. Finally, the third chapter is a presentation of the different graphical programs written in order to accelerate and rationalize the analysis phase [fr

  1. Transmural myocardial perfusion gradients in relation to coronary artery stenoses severity assessed by cardiac multidetector computed tomography

    DEFF Research Database (Denmark)

    Linde, Jesper James; Kühl, Jørgen Tobias; Hove, Jens Dahlgaard

    2015-01-01

    To assess the relationship between epicardial coronary artery stenosis severity and the corresponding regional transmural perfusion at rest and during adenosine stress, using multidetector computed tomography (MDCT). We evaluated the relationship between the severity of coronary artery diameter...

  2. Penetrating Colorectal Injuries: Diagnostic Performance of Multidetector CT with Trajectography.

    Science.gov (United States)

    Dreizin, David; Boscak, Alexis R; Anstadt, Michael J; Tirada, Nikki; Chiu, William C; Munera, Felipe; Bodanapally, Uttam K; Hornick, Michael; Stein, Deborah M

    2016-12-01

    Purpose To determine the diagnostic performance of multidetector computed tomography (CT) with trajectography for penetrating colorectal injuries. Materials and Methods This institutional review board-approved and HIPAA-compliant study was a 6-year blinded retrospective review by two independent readers of 182 consecutive patients who preoperatively underwent 40- or 64-row multidetector CT for penetrating torso trauma below the diaphragm and had surgically confirmed findings. Colorectal perforation was present in 42 patients. Trajectory analysis with postprocessing software was used for all studies. Additional signs evaluated were rectal contrast agent leak, collections of extruded fecal material, mural defect, wall thickening, abnormal enhancement, free fluid or stranding, and free air. The quality of the colorectal contrast agent administration was recorded. Sensitivity, specificity, predictive values, areas under the receiver operating characteristic curves (AUCs), and Cohen κ were determined. Results In patients with rectal contrast agent administration (n = 151), AUCs were 0.90-0.91, which indicated excellent accuracy. Trajectory was sensitive (88%-91%). For single wounds (n = 104), sensitivity of trajectory was 96% for both readers, but was only 80% for multiple wounds (n = 47). Contrast agent leak was highly specific (96%-98%), but insensitive (42%-46%). Improved diagnostic performance was observed in patients with poor colonic distension or opacification. Accuracy remained high (AUC, 0.86-0.99) in the group without rectal contrast agent administration (n = 31). Conclusion Trajectory had excellent sensitivity, while rectal contrast agent leak was specific but insensitive. Sensitivity of trajectory was lower for multiple wounds. Accuracy remained high in patients without rectal contrast agent administration. © RSNA, 2016.

  3. Detection of Airway Anomalies in?Pediatric?Patients with Cardiovascular Anomalies with Low Dose Prospective ECG-Gated Dual-Source CT

    OpenAIRE

    Jiao, Hui; Xu, Zhuodong; Wu, Lebin; Cheng, Zhaoping; Ji, Xiaopeng; Zhong, Hai; Meng, Chen

    2013-01-01

    OBJECTIVES: To assess the feasibility of low-dose prospective ECG-gated dual-source CT (DSCT) in detecting airway anomalies in pediatric patients with cardiovascular anomalies compared with flexible tracheobronchoscopy (FTB). METHODS: 33 pediatrics with respiratory symptoms who had been revealed cardiovascular anomalies by transthoracic echocardiography underwent FTB and contrast material-enhanced prospective ECG-triggering CT were enrolled. The study was approved by our institution review bo...

  4. Multidetector CT and MRI of ostial atresia of the coronary sinus, associated collateral venous pathways and cardiac anomalies

    International Nuclear Information System (INIS)

    Shum, J.S.F.; Kim, S.M.; Choe, Y.H.

    2012-01-01

    Aim: To analyse the multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) findings in patients with atresia of the coronary sinus orifice (CSA). Materials and methods: MDCT findings of 15 consecutive adult patients with CSAs were retrospectively analysed. The patients underwent contrast-enhanced electrocardiography-gated MDCT (n = 13) or both CT and MRI (n = 2). Results: The mean size of the coronary sinus (CS) was 14.2 mm (range 5.5–24 mm) and 11 patients (73.3%) showed CS dilatation (diameter ≥12 mm). The mean length of the atretic CS segment was 2.9 mm (range 0–8 mm). Different forms of venous collateral pathways were observed in the CSA patients. Nine (60%) of the 15 CSA patients had communication between the right atrium (RA; n = 6) or LA (n = 5) and CS via intraseptal veins; six patients (40%) had persistent left superior caval veins; communications were also observed between the CS and RA (n = 4) or LA (n = 4); two patients had collateral venous pathways between dilated cardiac veins with RA; two patients had unroofing of the CS as outlet channels. Nine patients (60%) had cardiac anomalies: coronary artery fistula to the pulmonary artery (n = 6) or left ventricular base and CS (n = 1), atrial septal defects (n = 2), and a ventricular septal defect (n = 1). Conclusion: CSA patients have venous collateral pathways and a high incidence of associated cardiovascular anomalies such as coronary artery fistulae and atrial septal defects.

  5. Evaluation of the Positional Uncertainty of a Liver Tumor using 4-Dimensional Computed Tomography and Gated Orthogonal Kilovolt Setup Images

    International Nuclear Information System (INIS)

    Ju, Sang Gyu; Hong, Chae Seon; Park, Hee Chul; Ahn, Jong Ho; Shin, Eun Hyuk; Shin, Jung Suk; Kim, Jin Sung; Han, Young Yih; Lim, Do Hoon; Choi, Doo Ho

    2010-01-01

    In order to evaluate the positional uncertainty of internal organs during radiation therapy for treatment of liver cancer, we measured differences in inter- and intra-fractional variation of the tumor position and tidal amplitude using 4-dimensional computed radiograph (DCT) images and gated orthogonal setup kilovolt (KV) images taken on every treatment using the on board imaging (OBI) and real time position management (RPM) system. Twenty consecutive patients who underwent 3-dimensional (3D) conformal radiation therapy for treatment of liver cancer participated in this study. All patients received a 4DCT simulation with an RT16 scanner and an RPM system. Lipiodol, which was updated near the target volume after transarterial chemoembolization or diaphragm was chosen as a surrogate for the evaluation of the position difference of internal organs. Two reference orthogonal (anterior and lateral) digital reconstructed radiograph (DRR) images were generated using CT image sets of 0% and 50% into the respiratory phases. The maximum tidal amplitude of the surrogate was measured from 3D conformal treatment planning. After setting the patient up with laser markings on the skin, orthogonal gated setup images at 50% into the respiratory phase were acquired at each treatment session with OBI and registered on reference DRR images by setting each beam center. Online inter-fractional variation was determined with the surrogate. After adjusting the patient setup error, orthogonal setup images at 0% and 50% into the respiratory phases were obtained and tidal amplitude of the surrogate was measured. Measured tidal amplitude was compared with data from 4DCT. For evaluation of intra-fractional variation, an orthogonal gated setup image at 50% into the respiratory phase was promptly acquired after treatment and compared with the same image taken just before treatment. In addition, a statistical analysis for the quantitative evaluation was performed. Medians of inter

  6. Procedural sedation and analgesia for respiratory-gated MR-HIFU in the liver : a feasibility study

    NARCIS (Netherlands)

    van Breugel, Marjolein; Wijlemans, JW; Vaessen, Hermanus H B; de Greef, Martijn; Moonen, Chrit T W; van den Bosch, Maurice A A J; Ries, Mario G

    2016-01-01

    BACKGROUND: Previous studies demonstrated both pre-clinically and clinically the feasibility of magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablations in the liver. To overcome the associated problem of respiratory motion of the ablation area, general anesthesia (GA) and

  7. Impact of Multidetector Computerized Tomography (MDCT) On The General Population

    Energy Technology Data Exchange (ETDEWEB)

    Leite, B.B.; Ribeiro, N.C. [Servico de Radiologia, Hospital de Curry Cabral, Rua da Beneficencia, 8, 1069-166 Lisboa (Portugal)

    2009-05-15

    Multidetector computerized tomography (MDCT) appeared in the early 1990s, as a technological evolution of computerized tomography. As one would expect, the evolution continues and, each year, more powerful equipments appear, with new medical applications. However, the general use of this technique has lead to the dramatic increase on the general population irradiation. Special concern is required regarding the most vulnerable groups, like the pediatric population, the pregnant and the young female. Due to a larger awareness of this irradiation risks, some initiatives have been developed, coming from different areas, aiming to maximize the benefit to risk ratio of MDCT. (author)

  8. Multidetector Computed Tomography in the Preoperative Workup of Hilar Cholangiocarcinoma

    International Nuclear Information System (INIS)

    Kim, Hyoung Jung; Lee, Dong Ho; Lim, Joo Won; Ko, Young Tae

    2009-01-01

    Hilar cholangiocarcinoma is associated with a dismal prognosis; however, curative resection may offer a chance of cure. Various factors should be considered in the surgical planning for curative resection. These factors include extent of bile duct involvement, relationship between portal vein and tumor involvement, diffuse hepato duodenal ligament infiltration, vascular invasion, lymph node metastasis, peritoneal seeding, and hepatic volume. Using high-quality volume data from multidetector-row computed tomography (MDCT) and adequate postprocessing images, radiologists can provide various types of information, imperative for curative resection of a hilar cholangiocarcinoma. This review illustrates the role of MDCT in the preoperative workup of hilar cholangiocarcinoma

  9. SU-F-T-514: Evaluation of the Accuracy of Free-Breathing and Deep Inspiration Breath-Hold Gated Beam Delivery Using An Elekta Linac

    International Nuclear Information System (INIS)

    Jermoumi, M; Cao, D; Housley, D; Shepard, D; Xie, R

    2016-01-01

    Purpose: In this study, we evaluated the performance of an Elekta linac in the delivery of gated radiotherapy. We examined whether the use of either a short gating window or a long beam hold impacts the accuracy of the delivery Methods: The performance of an Elekta linac in the delivery of gated radiotherapy was assessed using a 20cmX 20cm open field with the radiation delivered using a range of beam-on and beam-off time periods. Two SBRT plans were used to examine the accuracy of gated beam delivery for clinical treatment plans. For the SBRT cases, tests were performed for both free-breathing based gating and for gated delivery with a simulated breath-hold. A MatriXX 2D ion chamber array was used for data collection, and the gating accuracy was evaluated using gamma score. Results: For the 20cmX20cm open field, the gated beam delivery agreed closely with the non-gated delivery results. Discrepancies in the agreement, however, began to appear with a 5-to-1 ratio of the beam-off to beam-on. For these tight gating windows, each beam-on segment delivered a small number of monitor units. This finding was confirmed with dose distribution analysis from the delivery of the two VMAT plans where the gamma score(±1%,2%/1mm) showed passing rates in the range of 95% to 100% for gating windows of 25%, 38%, 50%, 63%, 75%, and 83%. Using a simulated sinusoidal breathing signal with a 4 second period, the gamma score of freebreathing gating and breath-hold gating deliveries were measured in the range of 95.7% to 100%. Conclusion: The results demonstrate that Elekta linacs can be used to accurately deliver respiratory gated treatments for both free-breathing and breath-hold patients. The accuracy of beams delivered in a gated delivery mode at low small MU proved higher than similar deliveries performed in a non-gated (manually interrupted) fashion.

  10. SU-F-T-514: Evaluation of the Accuracy of Free-Breathing and Deep Inspiration Breath-Hold Gated Beam Delivery Using An Elekta Linac

    Energy Technology Data Exchange (ETDEWEB)

    Jermoumi, M; Cao, D; Housley, D; Shepard, D [Department of Radiation Oncology, Swedish Cancer Institute, Seattle, WA (United States); Xie, R [Ironwood Cancer and Research Centers, Chandler, AZ (United States)

    2016-06-15

    Purpose: In this study, we evaluated the performance of an Elekta linac in the delivery of gated radiotherapy. We examined whether the use of either a short gating window or a long beam hold impacts the accuracy of the delivery Methods: The performance of an Elekta linac in the delivery of gated radiotherapy was assessed using a 20cmX 20cm open field with the radiation delivered using a range of beam-on and beam-off time periods. Two SBRT plans were used to examine the accuracy of gated beam delivery for clinical treatment plans. For the SBRT cases, tests were performed for both free-breathing based gating and for gated delivery with a simulated breath-hold. A MatriXX 2D ion chamber array was used for data collection, and the gating accuracy was evaluated using gamma score. Results: For the 20cmX20cm open field, the gated beam delivery agreed closely with the non-gated delivery results. Discrepancies in the agreement, however, began to appear with a 5-to-1 ratio of the beam-off to beam-on. For these tight gating windows, each beam-on segment delivered a small number of monitor units. This finding was confirmed with dose distribution analysis from the delivery of the two VMAT plans where the gamma score(±1%,2%/1mm) showed passing rates in the range of 95% to 100% for gating windows of 25%, 38%, 50%, 63%, 75%, and 83%. Using a simulated sinusoidal breathing signal with a 4 second period, the gamma score of freebreathing gating and breath-hold gating deliveries were measured in the range of 95.7% to 100%. Conclusion: The results demonstrate that Elekta linacs can be used to accurately deliver respiratory gated treatments for both free-breathing and breath-hold patients. The accuracy of beams delivered in a gated delivery mode at low small MU proved higher than similar deliveries performed in a non-gated (manually interrupted) fashion.

  11. Multidetector bone densitometer for supine lateral vertebral scanning of the lumbar spine

    International Nuclear Information System (INIS)

    Pommet, R.

    1990-01-01

    ORIS-ODX 240 bone densitometer is used to provide the density values of large group of women obtaining both frontal and lateral projection of the lumbar spine on each of them. This device is the prototype of Sophos L-XRA developed by CEA/DAMRI for SOPHA MEDICAL. It uses as photon source an X-ray tube with K-edge filtration (Neodyme oxide). The multidetector uses 24 NaI (Tl) scintillators, 24 PM tubes and 24 dual channel analyzers

  12. Bosniak classification of renal cystic lesions according to multidetector computed tomography findings; Classificacao de Bosniak das lesoes cisticas renais segundo achados na tomografia computadorizada multidetectores

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Christiana Maia Nobre Rocha de; Padilha, Igor Gomes; Farias, Lucas de Padua Gomes de; Rocha, Milzi Sarmento da, E-mail: maiachristiana@globo.com [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil); Maranhao, Carol Pontes de Miranda; Santos, Carla Jotta Justo dos [Clinica de Medicina Nuclear e Radiologia de Maceio (MedRadiUS), Maceio, AL (Brazil)

    2014-03-15

    Renal cystic lesions are usually diagnosed in the radiologists' practice and therefore their characterization is crucial to determine the clinical approach to be adopted and prognosis. The Bosniak classification based on computed tomography findings has allowed for standardization and categorization of lesions in increasing order of malignancy (I, II, IIF, III and IV) in a simple and accurate way. The present iconographic essay developed with multidetector computed tomography images of selected cases from the archives of the authors' institution, is aimed at describing imaging findings that can help in the diagnosis of renal cysts. (author)

  13. Prevalence of extra-cardiac findings on studies of noninvasive coronary angiography multidetector computed tomography 64 rows

    International Nuclear Information System (INIS)

    Carrascosa, Patricia M.; Capunay, Carlos M.; Deviggiano, A.; Melendez, F.; Carrascosa, Jorge M.; Garcia, M.

    2007-01-01

    The aim of this paper is to show the importance of evaluating in a full form images obtained from a studio of noninvasive coronary angiography by multidetector computed tomography (AC-TCMD). 90 users of AC-TCMD were evaluated retrospectively conducted between October 2006 and April 2007 with a multidetector tomography of 64-rows(Phillips Medical Systems) . The images were reprocessed with a maximum field of vision and determined the presence of extra-cardiac findings, which were classified according to their impact on the management and treatment of patient at 3 degrees: low, medium and high grade. The studies were assessed jointly by a cardiologist and a radiologist qualified for cardiac and corporal evaluation. Extra-cardiac findings were identified in 58 patients. There were 38 patients with findings of low grade, 31 medium grade and 1 high grade. It was recommended to 16 patients its monitoring by images on reasonable period of time [es

  14. Expert Oracle GoldenGate

    CERN Document Server

    Prusinski, Ben; Chung, Richard

    2011-01-01

    Expert Oracle GoldenGate is a hands-on guide to creating and managing complex data replication environments using the latest in database replication technology from Oracle. GoldenGate is the future in replication technology from Oracle, and aims to be best-of-breed. GoldenGate supports homogeneous replication between Oracle databases. It supports heterogeneous replication involving other brands such as Microsoft SQL Server and IBM DB2 Universal Server. GoldenGate is high-speed, bidirectional, highly-parallelized, and makes only a light impact on the performance of databases involved in replica

  15. Multidetector Computed Tomography and Neuroendocrine Pancreaticoduodenal Tumors

    International Nuclear Information System (INIS)

    Rappeport, E.D.; Palnaes Hansen, C.; Kjaer, A.; Knigge, U.

    2006-01-01

    Purpose: To investigate the accuracy of dedicated pancreatic multidetector computed tomography (MDCT) in the diagnosis of neuroendocrine pancreaticoduodenal tumors (NPTs). Material and Methods: MDCT and other imaging studies in patients with suspected NPTs were identified. Thirty dedicated MDCT studies were done in 23 patients. Fourteen patients (16 operations) subsequently had surgery. Imaging reports were reviewed and findings compared with surgical findings and findings in other imaging studies. Results: Patients with surgery : 19 NPTs (16 extrapancreatic gastrinomas and 3 pancreatic NPTs) were identified at surgery. MDCT identified 16 and somatostatin receptor scintigraphy (SRS) 11 out of 19 tumors. Endoscopic ultrasound detected 11 out of 14 NPTs. Patients without surgery : In 4 out of 9 patients, no NPTs were identified at MDCT. Conclusion: Dedicated MDCT of the pancreas can identify many NPTs, including small duodenal and periduodenal tumors, and the detection rate is better than reported in the older literature on CT

  16. Diagnostic performance of 64-slice multidetector coronary computed tomographic angiography in women.

    Science.gov (United States)

    Jug, Borut; Gupta, Mohit; Papazian, Jenny; Li, Dong; Tsang, Janet; Bhatia, Harpreet; Karlsberg, Ronald; Budoff, Matthew

    2012-12-01

    Diagnostic approach to chest pain in women is challenging, but still under-investigated. The purpose of this study was to assess the diagnostic performance of 64-slice multidetector coronary computed tomographic angiography (CCTA) in women with chest pain. We included 606 patients--255 women and 351 men (mean age 61 ± 12 years for both)--who had been referred for a CCTA and an invasive coronary angiography (diagnostic standard) because of chest pain, either as part of clinical work-up in two urban medical centers or as part of the multicenter ACCURACY trial. On a patient-based model, the sensitivity, specificity, and positive predictive value (PPV) and negative predictive value to detect ≥50% and ≥70% stenosis were 98%, 84%, 87%, and 97% and 96%, 83%, 77%, and 97%, respectively, for women and 97%, 83%, 89%, and 95% and 94%, 91%, 90%, and 94%, respectively, for men. There were no statistically significant differences between men and women in diagnostic performance measures except for the PPV of detecting a ≥70% stenosis (P = .007). In women with chest pain, 64-slice multidetector CCTA is at least as sensitive and specific as in men. Our findings suggest that CCTA is a promising diagnostic tool for timely detection and/or exclusion of CAD in symptomatic intermediate-risk female populations.

  17. Normal mediastinal and hilar lymph nodes in children on multi-detector row chest computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jong, Pim A. de; Nievelstein, Rutger-Jan A. [University Medical Center Utrecht and Wilhelmina Children' s Hospital, Department of Radiology, Utrecht (Netherlands)

    2012-02-15

    To study normal mediastinal and hilar lymph nodes on multi-detector chest computed tomography (CT). A cohort of 120 children aged 1-17 years underwent emergency CT, including the chest, after high-energy trauma. Axial 5-mm reconstructions were evaluated for lymph nodes at hilar and various mediastinal levels and the short-axis diameters were measured. At least one lymph node was found in 115 (96%) children, with subcarinal (69%), lower paratracheal (64%) and hilar (60%) nodes being most common. Up to 10 years of age most lymph nodes were smaller than or equal to 7 mm. In older children lymph nodes measuring up to 10-mm-short-axis diameter were found. Lymph nodes were rare along the mammary vessels, at lower oesophageal and at prevascular and posterior mediastinal levels in children. Mediastinal and hilar lymph nodes are more common than previously thought, probably because of increased detection by modern multi-detector CT. Lymph node location and age have to be taken into account when evaluating lymph nodes in the paediatric chest. (orig.)

  18. Normal mediastinal and hilar lymph nodes in children on multi-detector row chest computed tomography

    International Nuclear Information System (INIS)

    Jong, Pim A. de; Nievelstein, Rutger-Jan A.

    2012-01-01

    To study normal mediastinal and hilar lymph nodes on multi-detector chest computed tomography (CT). A cohort of 120 children aged 1-17 years underwent emergency CT, including the chest, after high-energy trauma. Axial 5-mm reconstructions were evaluated for lymph nodes at hilar and various mediastinal levels and the short-axis diameters were measured. At least one lymph node was found in 115 (96%) children, with subcarinal (69%), lower paratracheal (64%) and hilar (60%) nodes being most common. Up to 10 years of age most lymph nodes were smaller than or equal to 7 mm. In older children lymph nodes measuring up to 10-mm-short-axis diameter were found. Lymph nodes were rare along the mammary vessels, at lower oesophageal and at prevascular and posterior mediastinal levels in children. Mediastinal and hilar lymph nodes are more common than previously thought, probably because of increased detection by modern multi-detector CT. Lymph node location and age have to be taken into account when evaluating lymph nodes in the paediatric chest. (orig.)

  19. Quantitative assessment of bone defect healing by multidetector CT in a pig model

    International Nuclear Information System (INIS)

    Riegger, Carolin; Kroepil, Patric; Lanzman, Rotem S.; Miese, Falk R.; Antoch, Gerald; Scherer, Axel; Jungbluth, Pascal; Hakimi, Mohssen; Wild, Michael; Hakimi, Ahmad R.

    2012-01-01

    To evaluate multidetector CT volumetry in the assessment of bone defect healing in comparison to histopathological findings in an animal model. In 16 mini-pigs, a circumscribed tibial bone defect was created. Multidetector CT (MDCT) of the tibia was performed on a 64-row scanner 42 days after the operation. The extent of bone healing was estimated quantitatively by MDCT volumetry using a commercially available software programme (syngo Volume, Siemens, Germany).The volume of the entire defect (including all pixels from -100 to 3,000 HU), the nonconsolidated areas (-100 to 500 HU), and areas of osseous consolidation (500 to 3,000 HU) were assessed and the extent of consolidation was calculated. Histomorphometry served as the reference standard. The extent of osseous consolidation in MDCT volumetry ranged from 19 to 92% (mean 65.4 ± 18.5%). There was a significant correlation between histologically visible newly formed bone and the extent of osseous consolidation on MDCT volumetry (r = 0.82, P < 0.0001). A significant negative correlation was detected between osseous consolidation on MDCT and histological areas of persisting defect (r = -0.9, P < 0.0001). MDCT volumetry is a promising tool for noninvasive monitoring of bone healing, showing excellent correlation with histomorphometry. (orig.)

  20. Quantitative assessment of bone defect healing by multidetector CT in a pig model

    Energy Technology Data Exchange (ETDEWEB)

    Riegger, Carolin; Kroepil, Patric; Lanzman, Rotem S.; Miese, Falk R.; Antoch, Gerald; Scherer, Axel [University Duesseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Duesseldorf (Germany); Jungbluth, Pascal; Hakimi, Mohssen; Wild, Michael [University Duesseldorf, Medical Faculty, Department of Traumatology and Hand Surgery, Duesseldorf (Germany); Hakimi, Ahmad R. [Universtity Duesseldorf, Medical Faculty, Department of Oral Surgery, Duesseldorf (Germany)

    2012-05-15

    To evaluate multidetector CT volumetry in the assessment of bone defect healing in comparison to histopathological findings in an animal model. In 16 mini-pigs, a circumscribed tibial bone defect was created. Multidetector CT (MDCT) of the tibia was performed on a 64-row scanner 42 days after the operation. The extent of bone healing was estimated quantitatively by MDCT volumetry using a commercially available software programme (syngo Volume, Siemens, Germany).The volume of the entire defect (including all pixels from -100 to 3,000 HU), the nonconsolidated areas (-100 to 500 HU), and areas of osseous consolidation (500 to 3,000 HU) were assessed and the extent of consolidation was calculated. Histomorphometry served as the reference standard. The extent of osseous consolidation in MDCT volumetry ranged from 19 to 92% (mean 65.4 {+-} 18.5%). There was a significant correlation between histologically visible newly formed bone and the extent of osseous consolidation on MDCT volumetry (r = 0.82, P < 0.0001). A significant negative correlation was detected between osseous consolidation on MDCT and histological areas of persisting defect (r = -0.9, P < 0.0001). MDCT volumetry is a promising tool for noninvasive monitoring of bone healing, showing excellent correlation with histomorphometry. (orig.)

  1. Noninvasive imaging of coronary arteries: current and future role of multidetector row computer tomography

    International Nuclear Information System (INIS)

    Nedevska, M.; Stoinova, V.

    2006-01-01

    Full text: This review will present the current and future role of cardiac computer tomography (CCT), and particular multidetector CCT, for imaging of atherosclerotic pathologic changes of the coronary arteries. Atherosclerosis and its cardio-vascular complications represent one of the major issues of public health in industrial countries. Different imaging modalities, including invasive coronarography, have been aimed to the diagnosis of the disease, when it provokes symptomatic decrease of the blood flow. In spite of development of surgical and percutaneous methods for coronary revascularization, coronary artery disease remains the major cause of death in North America and Europe. This demonstrates the need of novel, complementary diagnostic strategies, aimed to identify asymptomatic stages as the basis of pharmacological interventions. Noninvasive coronary angiography with multidetector CT allows both assessment of luminal stenosis and subclinical disease of arterial wall. Large trails are missing now to understand and present what will be the role of this technology in the comprehensive assessment of patients, suspected of having CAD. Based on experience and current potentials we will describe how tomographic coronary imaging may eventually supplement traditional angiographic techniques in understanding the patterns of atherosclerotic CAD development

  2. Comprehensive cardiovascular ECG-gated MDCT as a standard diagnostic tool in patients with acute chest pain

    Energy Technology Data Exchange (ETDEWEB)

    Runza, G. [Department of Radiology, University of Palermo (Italy)], E-mail: grunza@sirm.org; La Grutta, L.; Alaimo, V. [Department of Radiology, University of Palermo (Italy); Evola, S. [Department of Cardiology, University of Palermo (Italy); Lo Re, F.; Bartolotta, T.V. [Department of Radiology, University of Palermo (Italy); Cademartiri, F. [Department of Radiology and Cardiology, Erasmus Medical Center, Rotterdam (Netherlands); Department of Radiology and Cardiology, Cardiovascular CT Unit, University Hospital, Parma (Italy); Midiri, M. [Department of Radiology, University of Palermo (Italy)

    2007-10-15

    Acute myocardial infarction, pulmonary embolism, and aortic dissection are diseases associated with acute chest pain and may lead to severe morbidity and mortality. These diseases may not be trivial to diagnose in the settings of emergency room. ECG-gated multi-detector computed tomography (MDCT), already established for the assessment of pulmonary embolism and aortic dissection, provides reliable information regarding the triage of patients with acute coronary syndrome in the emergency room. MDCT recently appeared to be logistically feasible and a promising comprehensive method for the evaluation of cardiac and non-cardiac chest pain in emergency department patients. The possibility to scan the entire thorax visualizing the thoracic aorta, the pulmonary arteries, and the coronary arteries could provide a new approach to the triage of acute chest pain. The inherent advantage of MDCT with cardiac state-of-the-art capabilities is the rapid investigation of the main sources of acute chest pain with a high negative predictive value. Recent studies also reports an advantage in terms of costs. With current evidence, the selection of patients with acute chest pain candidates to MDCT should remain restricted to avoid unjustified risk of ionizing radiation.

  3. Comprehensive cardiovascular ECG-gated MDCT as a standard diagnostic tool in patients with acute chest pain

    International Nuclear Information System (INIS)

    Runza, G.; La Grutta, L.; Alaimo, V.; Evola, S.; Lo Re, F.; Bartolotta, T.V.; Cademartiri, F.; Midiri, M.

    2007-01-01

    Acute myocardial infarction, pulmonary embolism, and aortic dissection are diseases associated with acute chest pain and may lead to severe morbidity and mortality. These diseases may not be trivial to diagnose in the settings of emergency room. ECG-gated multi-detector computed tomography (MDCT), already established for the assessment of pulmonary embolism and aortic dissection, provides reliable information regarding the triage of patients with acute coronary syndrome in the emergency room. MDCT recently appeared to be logistically feasible and a promising comprehensive method for the evaluation of cardiac and non-cardiac chest pain in emergency department patients. The possibility to scan the entire thorax visualizing the thoracic aorta, the pulmonary arteries, and the coronary arteries could provide a new approach to the triage of acute chest pain. The inherent advantage of MDCT with cardiac state-of-the-art capabilities is the rapid investigation of the main sources of acute chest pain with a high negative predictive value. Recent studies also reports an advantage in terms of costs. With current evidence, the selection of patients with acute chest pain candidates to MDCT should remain restricted to avoid unjustified risk of ionizing radiation

  4. Pulmonary nodules: sensitivity of maximum intensity projection versus that of volume rendering of 3D multidetector CT data

    NARCIS (Netherlands)

    Peloschek, Philipp; Sailer, Johannes; Weber, Michael; Herold, Christian J.; Prokop, Mathias; Schaefer-Prokop, Cornelia

    2007-01-01

    PURPOSE: To prospectively compare maximum intensity projection (MIP) and volume rendering (VR) of multidetector computed tomographic (CT) data for the detection of small intrapulmonary nodules. MATERIALS AND METHODS: This institutional review board-approved prospective study included 20 oncology

  5. GATE V6: a major enhancement of the GATE simulation platform enabling modelling of CT and radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Jan, S; Becheva, E [DSV/I2BM/SHFJ, Commissariat a l' Energie Atomique, Orsay (France); Benoit, D; Rehfeld, N; Stute, S; Buvat, I [IMNC-UMR 8165 CNRS-Paris 7 and Paris 11 Universities, 15 rue Georges Clemenceau, 91406 Orsay Cedex (France); Carlier, T [INSERM U892-Cancer Research Center, University of Nantes, Nantes (France); Cassol, F; Morel, C [Centre de physique des particules de Marseille, CNRS-IN2P3 and Universite de la Mediterranee, Aix-Marseille II, 163, avenue de Luminy, 13288 Marseille Cedex 09 (France); Descourt, P; Visvikis, D [INSERM, U650, Laboratoire du Traitement de l' Information Medicale (LaTIM), CHU Morvan, Brest (France); Frisson, T; Grevillot, L; Guigues, L; Sarrut, D; Zahra, N [Universite de Lyon, CREATIS, CNRS UMR5220, Inserm U630, INSA-Lyon, Universite Lyon 1, Centre Leon Berard (France); Maigne, L; Perrot, Y [Laboratoire de Physique Corpusculaire, 24 Avenue des Landais, 63177 Aubiere Cedex (France); Schaart, D R [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Pietrzyk, U, E-mail: buvat@imnc.in2p3.fr [Reseach Center Juelich, Institute of Neurosciences and Medicine and Department of Physics, University of Wuppertal (Germany)

    2011-02-21

    GATE (Geant4 Application for Emission Tomography) is a Monte Carlo simulation platform developed by the OpenGATE collaboration since 2001 and first publicly released in 2004. Dedicated to the modelling of planar scintigraphy, single photon emission computed tomography (SPECT) and positron emission tomography (PET) acquisitions, this platform is widely used to assist PET and SPECT research. A recent extension of this platform, released by the OpenGATE collaboration as GATE V6, now also enables modelling of x-ray computed tomography and radiation therapy experiments. This paper presents an overview of the main additions and improvements implemented in GATE since the publication of the initial GATE paper (Jan et al 2004 Phys. Med. Biol. 49 4543-61). This includes new models available in GATE to simulate optical and hadronic processes, novelties in modelling tracer, organ or detector motion, new options for speeding up GATE simulations, examples illustrating the use of GATE V6 in radiotherapy applications and CT simulations, and preliminary results regarding the validation of GATE V6 for radiation therapy applications. Upon completion of extensive validation studies, GATE is expected to become a valuable tool for simulations involving both radiotherapy and imaging.

  6. List-mode-based reconstruction for respiratory motion correction in PET using non-rigid body transformations

    International Nuclear Information System (INIS)

    Lamare, F; Carbayo, M J Ledesma; Cresson, T; Kontaxakis, G; Santos, A; Rest, C Cheze Le; Reader, A J; Visvikis, D

    2007-01-01

    Respiratory motion in emission tomography leads to reduced image quality. Developed correction methodology has been concentrating on the use of respiratory synchronized acquisitions leading to gated frames. Such frames, however, are of low signal-to-noise ratio as a result of containing reduced statistics. In this work, we describe the implementation of an elastic transformation within a list-mode-based reconstruction for the correction of respiratory motion over the thorax, allowing the use of all data available throughout a respiratory motion average acquisition. The developed algorithm was evaluated using datasets of the NCAT phantom generated at different points throughout the respiratory cycle. List-mode-data-based PET-simulated frames were subsequently produced by combining the NCAT datasets with Monte Carlo simulation. A non-rigid registration algorithm based on B-spline basis functions was employed to derive transformation parameters accounting for the respiratory motion using the NCAT dynamic CT images. The displacement matrices derived were subsequently applied during the image reconstruction of the original emission list mode data. Two different implementations for the incorporation of the elastic transformations within the one-pass list mode EM (OPL-EM) algorithm were developed and evaluated. The corrected images were compared with those produced using an affine transformation of list mode data prior to reconstruction, as well as with uncorrected respiratory motion average images. Results demonstrate that although both correction techniques considered lead to significant improvements in accounting for respiratory motion artefacts in the lung fields, the elastic-transformation-based correction leads to a more uniform improvement across the lungs for different lesion sizes and locations

  7. Acute pulmonary embolism: prediction of cor pulmonale and short-term patient survival from assessment of cardiac dimensions in routine multidetector-row CT

    International Nuclear Information System (INIS)

    Engeike, C.; Rummeny, E.; Marten, K.

    2006-01-01

    Purpose: evaluation of the prognostic value of morphological cardiac parameters in patients with suspected and incidental acute pulmonary embolism (PE) using multidetector-row chest CT (MSCT). Materials and methods: 2335 consecutive MSCT scans were evaluated for the presence of PE. The arterial enhancement and analysability of pulmonary arteries and the heart were assessed as parameters of the scan quality. The diastolic right and left ventricular short axes (RV D , LV D ) and the interventricular septal deviation (ISD) were measured in all PE-positive patients and the echocardiography reports were reviewed. The clinical data assessment included cardio-respiratory and other co-morbidities, systemic anticoagulant therapy (ACT), and the 30-day outcome. Predictors of acute cor pulmonale and the short-term outcome were calculated by univariate and multivariate logistic regressions including odds ratios (OR) and ROC analyses using positive (PPV) and negative predictive values (NPV). Results: 90 patients with acute PE were included (36 with clinically suspected PE, 54 with incidental PE). 26 patients had cardio-respiratory co-morbidities. Four patients underwent systemic thrombolysis, 43 underwent anticoagulation in therapeutic doses, 19 underwent anticoagulation in prophylactic doses, and 24 patients did not undergo ACT. 15 of 41 patients had echocardiographic evidence of acute cor pulmonale. 8 patients died within 30 days. The RV D was the best independent predictor of acute cor pulmonale (p = 0,002, OR = 9.16, PPV = 0.68, NPV=1 at 4.49 cm cut off) and short-term outcome (p= 0,0005, OR = 2.82, PPV = 0.23, NPV = 0.98 at 4.75 cm cut off). The RV D /LV D ratio had a PPV of 0.85 for cor pulmonale. (orig.)

  8. Program system for processing of spectra obtained on the multidetector correlation device (MUK)

    International Nuclear Information System (INIS)

    Venos, D.; Adam, J.; Hnatowicz, V.; Honusek, M.

    1988-01-01

    A program system used by evaluation of multidimensional coincidence spectra is described. The spectra recorded on magnetic tapes are obtained by means of multidetector correlation device (MUK). The angular correlation coefficients A 22 and A 44 for the given cascades of gamma transitions are the final result of the calculations. The system operates in DOS/ES system of the EC-1040 computer with the 1024 Kbyte memeory. All the codes are written in fortran language

  9. Novel Quantum Dot Gate FETs and Nonvolatile Memories Using Lattice-Matched II-VI Gate Insulators

    Science.gov (United States)

    Jain, F. C.; Suarez, E.; Gogna, M.; Alamoody, F.; Butkiewicus, D.; Hohner, R.; Liaskas, T.; Karmakar, S.; Chan, P.-Y.; Miller, B.; Chandy, J.; Heller, E.

    2009-08-01

    This paper presents the successful use of ZnS/ZnMgS and other II-VI layers (lattice-matched or pseudomorphic) as high- k gate dielectrics in the fabrication of quantum dot (QD) gate Si field-effect transistors (FETs) and nonvolatile memory structures. Quantum dot gate FETs and nonvolatile memories have been fabricated in two basic configurations: (1) monodispersed cladded Ge nanocrystals (e.g., GeO x -cladded-Ge quantum dots) site-specifically self-assembled over the lattice-matched ZnMgS gate insulator in the channel region, and (2) ZnTe-ZnMgTe quantum dots formed by self-organization, using metalorganic chemical vapor-phase deposition (MOCVD), on ZnS-ZnMgS gate insulator layers grown epitaxially on Si substrates. Self-assembled GeO x -cladded Ge QD gate FETs, exhibiting three-state behavior, are also described. Preliminary results on InGaAs-on-InP FETs, using ZnMgSeTe/ZnSe gate insulator layers, are presented.

  10. Pneumomediastinum on Multidetector CT: The Radiologic Signs and Underlying Disorders

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Soo Jin; Kim, Young Tong [Soonchunhyang University Chunan Hospital, Cheonan (Korea, Republic of)

    2011-02-15

    We can see the typical signs of pneumomediastinum on chest radiography and we can also see them on the multiplanar reformatted (MPR) image of multidetector CT (MDCT). MDCT can help to understand the anatomical feature of these signs and differentiate pneumomediastinum from pneumothorax, pneumopericardium and the Mach band effect. MDCT shows the peribronchovascular air, which reveals the Macklin effect, and it can also evaluate the underlying disorders that cause pneumomediastinum. The purpose of this pictorial essay is to inform physicians about the mechanism and anatomical features of pneumomediastinum, and to help them understand the imaging findings and underlying disorders of pneumomediastinum as seen on MDCT

  11. Multidetector Computer Tomography: Evaluation of Blunt Chest Trauma in Adults

    International Nuclear Information System (INIS)

    Palas, J.; Matos, A.P.; Ramalho, M.; Mascarenhas, V.; Heredia, V.

    2014-01-01

    Imaging plays an essential part of chest trauma care. By definition, the employed imaging technique in the emergency setting should reach the correct diagnosis as fast as possible. In severe chest blunt trauma, multidetector computer tomography (MDCT) has become part of the initial workup, mainly due to its high sensitivity and diagnostic accuracy of the technique for the detection and characterization of thoracic injuries and also due to its wide availability in tertiary care centers. The aim of this paper is to review and illustrate a spectrum of characteristic MDCT findings of blunt traumatic injuries of the chest including the lungs, mediastinum, pleural space, and chest wall.

  12. Multidetector Computer Tomography: Evaluation of Blunt Chest Trauma in Adults

    Directory of Open Access Journals (Sweden)

    João Palas

    2014-01-01

    Full Text Available Imaging plays an essential part of chest trauma care. By definition, the employed imaging technique in the emergency setting should reach the correct diagnosis as fast as possible. In severe chest blunt trauma, multidetector computer tomography (MDCT has become part of the initial workup, mainly due to its high sensitivity and diagnostic accuracy of the technique for the detection and characterization of thoracic injuries and also due to its wide availability in tertiary care centers. The aim of this paper is to review and illustrate a spectrum of characteristic MDCT findings of blunt traumatic injuries of the chest including the lungs, mediastinum, pleural space, and chest wall.

  13. Impact of window size of extracranial stereotactic treatments Gating with respiratory synchronization; Analisis de las correcciones interfraccion en el posicionamiento de los pacientes mediante IGRT

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Rubio, P.; Castro Tejero, P.; Medrano Prado, J. C.

    2011-07-01

    The choice of the gating window is to find a compromise between the duration of the treatment session and the accuracy and precision in the administration. This paper analyzes the dosimetric impact depending on the selected gating window.

  14. New opening hours of the gates

    CERN Multimedia

    GS Department

    2009-01-01

    Please note the new opening hours of the gates as well as the intersites tunnel from the 19 May 2009: GATE A 7h - 19h GATE B 24h/24 GATE C 7h - 9h\t17h - 19h GATE D 8h - 12h\t13h - 16h GATE E 7h - 9h\t17h - 19h Prévessin 24h/24 The intersites tunnel will be opened from 7h30 to 18h non stop. GS-SEM Group Infrastructure and General Services Department

  15. The use of a position sensitive detector or of a multidetector for the measurement of pole figures by neutron time-of-flight technique

    International Nuclear Information System (INIS)

    Walther, K.

    1990-01-01

    The neutron flux of even high flux reactors is weak in comparison with the quantum flux of X-ray tubes and therefore in order to decrease the expense on measuring time more and more neutron diffractometers are equipped with position sensitive detectors or multidetectors. In this paper the peculiarities of the use of such detecting devices are discussed for the measurement of pole figures. A special arrangement of a multidetector is proposed which will allow one to scan the whole pole figure by rotating the sample about only one axis and considerably will save measuring time. 4 refs.; 5 figs

  16. Optical XOR gate

    Science.gov (United States)

    Vawter, G. Allen

    2013-11-12

    An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

  17. Signatures of Mechanosensitive Gating.

    Science.gov (United States)

    Morris, Richard G

    2017-01-10

    The question of how mechanically gated membrane channels open and close is notoriously difficult to address, especially if the protein structure is not available. This perspective highlights the relevance of micropipette-aspirated single-particle tracking-used to obtain a channel's diffusion coefficient, D, as a function of applied membrane tension, σ-as an indirect assay for determining functional behavior in mechanosensitive channels. While ensuring that the protein remains integral to the membrane, such methods can be used to identify not only the gating mechanism of a protein, but also associated physical moduli, such as torsional and dilational rigidity, which correspond to the protein's effective shape change. As an example, three distinct D-versus-σ "signatures" are calculated, corresponding to gating by dilation, gating by tilt, and gating by a combination of both dilation and tilt. Both advantages and disadvantages of the approach are discussed. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  18. Quantum gate decomposition algorithms.

    Energy Technology Data Exchange (ETDEWEB)

    Slepoy, Alexander

    2006-07-01

    Quantum computing algorithms can be conveniently expressed in a format of a quantum logical circuits. Such circuits consist of sequential coupled operations, termed ''quantum gates'', or quantum analogs of bits called qubits. We review a recently proposed method [1] for constructing general ''quantum gates'' operating on an qubits, as composed of a sequence of generic elementary ''gates''.

  19. [The role of multidetector computer tomography in diagnosis of acute pancreatitis].

    Science.gov (United States)

    Lohanikhina, K Iu; Hordiienko, K P; Kozarenko, T M

    2014-10-01

    With the objective to improve the diagnostic semiotics of an acute pancreatitis (AP) 35 patients were examined, using 64-cut computeric tomograph Lightspeed VCT (GE, USA) with intravenous augmentation in arterial and portal phases. Basing on analysis of the investigations conducted, using multidetector computeric tomography (MDCT), the AP semiotics was systematized, which is characteristic for oedematous and destructive forms, diagnosed in 19 (44.2%) and 16 (45.8%) patients, accordingly. The procedure for estimation of preservation of the organ functional capacity in pancreonecrosis pres- ence was elaborated, promoting rising of the method diagnostic efficacy by 5.3 - 9.4%.

  20. Evaluation of aortogenic embolic stroke using multi-detector row CT (MDCT)

    International Nuclear Information System (INIS)

    Mizuno, Masanori; Ooura, Kazumasa; Yamaguchi, Mao; Katsura, Noriyuki; Terayama, Yasuo

    2010-01-01

    Transesophageal cardioechography is one of the useful tools for detecting aortic arteriosclerosis causing aortogenic cerebral embolism. However, it is difficult to perform this method to all of the patients because of the technical difficulties due to patient's condition, especially the severity of atherosclerosis. To avoid the unexpected and adverse events, we are routinely applying multi-detector row CT (MDCT) to those patients. Among 10 cerebral embolic patients with unidentified embolic origin, MDCT revealed arteriosclerotic changes in aorta inducing mobile thrombus in 3 cases. The above data indicates that MDCT is safe and useful tool for diagnosis of aortogenic embolic stroke. (author)