A respiratory monitoring device based on clavicular motion

International Nuclear Information System (INIS)

Pitts, D G; Aspinall, R; Patel, M K; Lang, P-O; Sinclair, A J

2013-01-01

Respiratory rate is one of the key vital signs yet unlike temperature, heart rate or blood pressure, there is no simple and low cost measurement device for medical use. Here we discuss the development of a respiratory sensor based upon clavicular motion and the findings of a pilot study comparing respiratory rate readings derived from clavicular and thoracic motion with an expiratory breath flow reference sensor. Simultaneously sampled data from resting volunteers (n = 8) was analysed to determine the location of individual breaths in the data set and from these, breath periods and frequency were calculated. Clavicular sensor waveforms were found to be more consistent and of greater amplitude than those from the thoracic device, demonstrating good alignment with the reference waveform. On comparing breath by breath periods a close agreement was observed with the reference, with mean clavicular respiratory rate R 2 values of 0.89 (lateral) and 0.98 (longitudinal-axis). This pilot study demonstrates the viability of clavicular respiratory sensing. The sensor is unobtrusive, unaffected by bioelectrical or electrode problems and easier to determine and more consistent than thoracic motion sensing. With relatively basic signal conditioning and processing requirements, it could provide an ideal platform for a low-cost respiratory monitor. (note)

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

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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)

Verification and compensation of respiratory motion using an ultrasound imaging system

International Nuclear Information System (INIS)

Chuang, Ho-Chiao; Hsu, Hsiao-Yu; Chiu, Wei-Hung; Tien, Der-Chi; Wu, Ren-Hong; Hsu, Chung-Hsien

2015-01-01

Purpose: The purpose of this study was to determine if it is feasible to use ultrasound imaging as an aid for moving the treatment couch during diagnosis and treatment procedures associated with radiation therapy, in order to offset organ displacement caused by respiratory motion. A noninvasive ultrasound system was used to replace the C-arm device during diagnosis and treatment with the aims of reducing the x-ray radiation dose on the human body while simultaneously being able to monitor organ displacements. Methods: This study used a proposed respiratory compensating system combined with an ultrasound imaging system to monitor the compensation effect of respiratory motion. The accuracy of the compensation effect was verified by fluoroscopy, which means that fluoroscopy could be replaced so as to reduce unnecessary radiation dose on patients. A respiratory simulation system was used to simulate the respiratory motion of the human abdomen and a strain gauge (respiratory signal acquisition device) was used to capture the simulated respiratory signals. The target displacements could be detected by an ultrasound probe and used as a reference for adjusting the gain value of the respiratory signal used by the respiratory compensating system. This ensured that the amplitude of the respiratory compensation signal was a faithful representation of the target displacement. Results: The results show that performing respiratory compensation with the assistance of the ultrasound images reduced the compensation error of the respiratory compensating system to 0.81–2.92 mm, both for sine-wave input signals with amplitudes of 5, 10, and 15 mm, and human respiratory signals; this represented compensation of the respiratory motion by up to 92.48%. In addition, the respiratory signals of 10 patients were captured in clinical trials, while their diaphragm displacements were observed simultaneously using ultrasound. Using the respiratory compensating system to offset, the diaphragm

Guidelines for respiratory motion management in radiation therapy

International Nuclear Information System (INIS)

Matsuo, Yukinori; Onishi, Hiroshi; Nakagawa, Keiichi

2013-01-01

Respiratory motion management (RMM) systems in external and stereotactic radiotherapies have been developed in the past two decades. Japanese medical service fee regulations introduced reimbursement for RMM from April 2012. Based on thorough discussions among the four academic societies concerned, these Guidelines have been developed to enable staff (radiation oncologists, radiological technologists, medical physicists, radiotherapy quality managers, radiation oncology nurses, and others) to apply RMM to radiation therapy for tumors subject to respiratory motion, safely and appropriately. (author)

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

Five-dimensional motion compensation for respiratory and cardiac motion with cone-beam CT of the thorax region

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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.

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

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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.

Evaluating and comparing algorithms for respiratory motion prediction

International Nuclear Information System (INIS)

Ernst, F; Dürichen, R; Schlaefer, A; Schweikard, A

2013-01-01

In robotic radiosurgery, it is necessary to compensate for systematic latencies arising from target tracking and mechanical constraints. This compensation is usually achieved by means of an algorithm which computes the future target position. In most scientific works on respiratory motion prediction, only one or two algorithms are evaluated on a limited amount of very short motion traces. The purpose of this work is to gain more insight into the real world capabilities of respiratory motion prediction methods by evaluating many algorithms on an unprecedented amount of data. We have evaluated six algorithms, the normalized least mean squares (nLMS), recursive least squares (RLS), multi-step linear methods (MULIN), wavelet-based multiscale autoregression (wLMS), extended Kalman filtering, and ε-support vector regression (SVRpred) methods, on an extensive database of 304 respiratory motion traces. The traces were collected during treatment with the CyberKnife (Accuray, Inc., Sunnyvale, CA, USA) and feature an average length of 71 min. Evaluation was done using a graphical prediction toolkit, which is available to the general public, as is the data we used. The experiments show that the nLMS algorithm—which is one of the algorithms currently used in the CyberKnife—is outperformed by all other methods. This is especially true in the case of the wLMS, the SVRpred, and the MULIN algorithms, which perform much better. The nLMS algorithm produces a relative root mean square (RMS) error of 75% or less (i.e., a reduction in error of 25% or more when compared to not doing prediction) in only 38% of the test cases, whereas the MULIN and SVRpred methods reach this level in more than 77%, the wLMS algorithm in more than 84% of the test cases. Our work shows that the wLMS algorithm is the most accurate algorithm and does not require parameter tuning, making it an ideal candidate for clinical implementation. Additionally, we have seen that the structure of a patient�

The impact of respiratory motion on tumor quantification and delineation in static PET/CT imaging

International Nuclear Information System (INIS)

Liu Chi; Pierce II, Larry A; Alessio, Adam M; Kinahan, Paul E

2009-01-01

Our aim is to investigate the impact of respiratory motion on tumor quantification and delineation in static PET/CT imaging using a population of patient respiratory traces. A total of 1295 respiratory traces acquired during whole body PET/CT imaging were classified into three types according to the qualitative shape of their signal histograms. Each trace was scaled to three diaphragm motion amplitudes (6 mm, 11 mm and 16 mm) to drive a whole body PET/CT computer simulation that was validated with a physical phantom experiment. Three lung lesions and one liver lesion were simulated with diameters of 1 cm and 2 cm. PET data were reconstructed using the OS-EM algorithm with attenuation correction using CT images at the end-expiration phase and respiratory-averaged CT. The errors of the lesion maximum standardized uptake values (SUV max ) and lesion volumes between motion-free and motion-blurred PET/CT images were measured and analyzed. For respiration with 11 mm diaphragm motion and larger quiescent period fraction, respiratory motion can cause a mean lesion SUV max underestimation of 28% and a mean lesion volume overestimation of 130% in PET/CT images with 1 cm lesions. The errors of lesion SUV max and volume are larger for patient traces with larger motion amplitudes. Smaller lesions are more sensitive to respiratory motion than larger lesions for the same motion amplitude. Patient respiratory traces with relatively larger quiescent period fraction yield results less subject to respiratory motion than traces with long-term amplitude variability. Mismatched attenuation correction due to respiratory motion can cause SUV max overestimation for lesions in the lower lung region close to the liver dome. Using respiratory-averaged CT for attenuation correction yields smaller mismatch errors than those using end-expiration CT. Respiratory motion can have a significant impact on static oncological PET/CT imaging where SUV and/or volume measurements are important. The impact

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

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.

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

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

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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.

Shape-correlated deformation statistics for respiratory motion prediction in 4D lung

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Liu, Xiaoxiao; Oguz, Ipek; Pizer, Stephen M.; Mageras, Gig S.

2010-02-01

4D image-guided radiation therapy (IGRT) for free-breathing lungs is challenging due to the complicated respiratory dynamics. Effective modeling of respiratory motion is crucial to account for the motion affects on the dose to tumors. We propose a shape-correlated statistical model on dense image deformations for patient-specic respiratory motion estimation in 4D lung IGRT. Using the shape deformations of the high-contrast lungs as the surrogate, the statistical model trained from the planning CTs can be used to predict the image deformation during delivery verication time, with the assumption that the respiratory motion at both times are similar for the same patient. Dense image deformation fields obtained by diffeomorphic image registrations characterize the respiratory motion within one breathing cycle. A point-based particle optimization algorithm is used to obtain the shape models of lungs with group-wise surface correspondences. Canonical correlation analysis (CCA) is adopted in training to maximize the linear correlation between the shape variations of the lungs and the corresponding dense image deformations. Both intra- and inter-session CT studies are carried out on a small group of lung cancer patients and evaluated in terms of the tumor location accuracies. The results suggest potential applications using the proposed method.

Event-by-Event Continuous Respiratory Motion Correction for Dynamic PET Imaging.

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Yu, Yunhan; Chan, Chung; Ma, Tianyu; Liu, Yaqiang; Gallezot, Jean-Dominique; Naganawa, Mika; Kelada, Olivia J; Germino, Mary; Sinusas, Albert J; Carson, Richard E; Liu, Chi

2016-07-01

Existing respiratory motion-correction methods are applied only to static PET imaging. We have previously developed an event-by-event respiratory motion-correction method with correlations between internal organ motion and external respiratory signals (INTEX). This method is uniquely appropriate for dynamic imaging because it corrects motion for each time point. In this study, we applied INTEX to human dynamic PET studies with various tracers and investigated the impact on kinetic parameter estimation. The use of 3 tracers-a myocardial perfusion tracer, (82)Rb (n = 7); a pancreatic β-cell tracer, (18)F-FP(+)DTBZ (n = 4); and a tumor hypoxia tracer, (18)F-fluoromisonidazole ((18)F-FMISO) (n = 1)-was investigated in a study of 12 human subjects. Both rest and stress studies were performed for (82)Rb. The Anzai belt system was used to record respiratory motion. Three-dimensional internal organ motion in high temporal resolution was calculated by INTEX to guide event-by-event respiratory motion correction of target organs in each dynamic frame. Time-activity curves of regions of interest drawn based on end-expiration PET images were obtained. For (82)Rb studies, K1 was obtained with a 1-tissue model using a left-ventricle input function. Rest-stress myocardial blood flow (MBF) and coronary flow reserve (CFR) were determined. For (18)F-FP(+)DTBZ studies, the total volume of distribution was estimated with arterial input functions using the multilinear analysis 1 method. For the (18)F-FMISO study, the net uptake rate Ki was obtained with a 2-tissue irreversible model using a left-ventricle input function. All parameters were compared with the values derived without motion correction. With INTEX, K1 and MBF increased by 10% ± 12% and 15% ± 19%, respectively, for (82)Rb stress studies. CFR increased by 19% ± 21%. For studies with motion amplitudes greater than 8 mm (n = 3), K1, MBF, and CFR increased by 20% ± 12%, 30% ± 20%, and 34% ± 23%, respectively. For (82)Rb

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

Anthropomorphic thorax phantom for cardio-respiratory motion simulation in tomographic imaging

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Bolwin, Konstantin; Czekalla, Björn; Frohwein, Lynn J.; Büther, Florian; Schäfers, Klaus P.

2018-02-01

Patient motion during medical imaging using techniques such as computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), or single emission computed tomography (SPECT) is well known to degrade images, leading to blurring effects or severe artifacts. Motion correction methods try to overcome these degrading effects. However, they need to be validated under realistic conditions. In this work, a sophisticated anthropomorphic thorax phantom is presented that combines several aspects of a simulator for cardio-respiratory motion. The phantom allows us to simulate various types of cardio-respiratory motions inside a human-like thorax, including features such as inflatable lungs, beating left ventricular myocardium, respiration-induced motion of the left ventricle, moving lung lesions, and moving coronary artery plaques. The phantom is constructed to be MR-compatible. This means that we can not only perform studies in PET, SPECT and CT, but also inside an MRI system. The technical features of the anthropomorphic thorax phantom Wilhelm are presented with regard to simulating motion effects in hybrid emission tomography and radiotherapy. This is supplemented by a study on the detectability of small coronary plaque lesions in PET/CT under the influence of cardio-respiratory motion, and a study on the accuracy of left ventricular blood volumes.

The application of the sinusoidal model to lung cancer patient respiratory motion

International Nuclear Information System (INIS)

George, R.; Vedam, S.S.; Chung, T.D.; Ramakrishnan, V.; Keall, P.J.

2005-01-01

Accurate modeling of the respiratory cycle is important to account for the effect of organ motion on dose calculation for lung cancer patients. The aim of this study is to evaluate the accuracy of a respiratory model for lung cancer patients. Lujan et al. [Med. Phys. 26(5), 715-720 (1999)] proposed a model, which became widely used, to describe organ motion due to respiration. This model assumes that the parameters do not vary between and within breathing cycles. In this study, first, the correlation of respiratory motion traces with the model f(t) as a function of the parameter n(n=1,2,3) was undertaken for each breathing cycle from 331 four-minute respiratory traces acquired from 24 lung cancer patients using three breathing types: free breathing, audio instruction, and audio-visual biofeedback. Because cos 2 and cos 4 had similar correlation coefficients, and cos 2 and cos 1 have a trigonometric relationship, for simplicity, the cos 1 value was consequently used for further analysis in which the variations in mean position (z 0 ), amplitude of motion (b) and period (τ) with and without biofeedback or instructions were investigated. For all breathing types, the parameter values, mean position (z 0 ), amplitude of motion (b), and period (τ) exhibited significant cycle-to-cycle variations. Audio-visual biofeedback showed the least variations for all three parameters (z 0 , b, and τ). It was found that mean position (z 0 ) could be approximated with a normal distribution, and the amplitude of motion (b) and period (τ) could be approximated with log normal distributions. The overall probability density function (pdf) of f(t) for each of the three breathing types was fitted with three models: normal, bimodal, and the pdf of a simple harmonic oscillator. It was found that the normal and the bimodal models represented the overall respiratory motion pdfs with correlation values from 0.95 to 0.99, whereas the range of the simple harmonic oscillator pdf correlation

Simulation of respiratory motion during IMRT dose delivery

International Nuclear Information System (INIS)

Mohn, Silje; Wasboe, Ellen

2011-01-01

Background. When intensity modulated radiation therapy (IMRT) is realised with dynamic multi-leaf collimators (MLC) and given under respiratory motion, dosimetric errors may occur. These errors are a consequence of the dose blurring and the interplay between the organ motion and the leaf motion. In the present study, a model for evaluating these dosimetric effects for patient-specific cases has been developed and tested. Material and methods. In the purpose written software, three dimensional (3D) dose distributions can be calculated both with and without a generated breathing cycle. To validate the presented model and illustrate its application, periodic breathing cycles were generated, where the starting phase was set randomly for each field during the calculations. Respiration in the anterior-posterior (AP), superior-inferior (SI) and left-right (LR) direction was tested and verified. To illustrate the application of the presented model, two 5-fields IMRT plans with different complexity were calculated with a 2 cm peak-to-peak motion in the AP direction for one fraction and for 25 fractions. Results. The results showed that the calculation method is of good accuracy, in particular for IMRT plans consisting of several fields, where 97% of the pixels within the body fulfilled a tolerance set to 4% dose difference and 4 mm distance to agreement (DTA). For the two IMRT plans with different complexity, pronounced respiratory induced dose errors, which increased with increasing complexity, were found for both one fraction and 25 fractions, but due to the random stating phase the interplay effect was considerably reduced for the plans consisting of 25 fractions. This illustrates how the dosimetric effects will vary depending on the dose plan and on the number of fractions investigated. Conclusion. For patient specific cases, the model can with good accuracy calculate 3D dose distributions both with and without respiratory motion, and evaluate the dosimetric effects

Real-time tumor motion estimation using respiratory surrogate via memory-based learning

International Nuclear Information System (INIS)

Li Ruijiang; Xing Lei; Lewis, John H; Berbeco, Ross I

2012-01-01

Respiratory tumor motion is a major challenge in radiation therapy for thoracic and abdominal cancers. Effective motion management requires an accurate knowledge of the real-time tumor motion. External respiration monitoring devices (optical, etc) provide a noninvasive, non-ionizing, low-cost and practical approach to obtain the respiratory signal. Due to the highly complex and nonlinear relations between tumor and surrogate motion, its ultimate success hinges on the ability to accurately infer the tumor motion from respiratory surrogates. Given their widespread use in the clinic, such a method is critically needed. We propose to use a powerful memory-based learning method to find the complex relations between tumor motion and respiratory surrogates. The method first stores the training data in memory and then finds relevant data to answer a particular query. Nearby data points are assigned high relevance (or weights) and conversely distant data are assigned low relevance. By fitting relatively simple models to local patches instead of fitting one single global model, it is able to capture highly nonlinear and complex relations between the internal tumor motion and external surrogates accurately. Due to the local nature of weighting functions, the method is inherently robust to outliers in the training data. Moreover, both training and adapting to new data are performed almost instantaneously with memory-based learning, making it suitable for dynamically following variable internal/external relations. We evaluated the method using respiratory motion data from 11 patients. The data set consists of simultaneous measurement of 3D tumor motion and 1D abdominal surface (used as the surrogate signal in this study). There are a total of 171 respiratory traces, with an average peak-to-peak amplitude of ∼15 mm and average duration of ∼115 s per trace. Given only 5 s (roughly one breath) pretreatment training data, the method achieved an average 3D error of 1.5 mm and 95

Real-time tumor motion estimation using respiratory surrogate via memory-based learning

Science.gov (United States)

Li, Ruijiang; Lewis, John H.; Berbeco, Ross I.; Xing, Lei

2012-08-01

Respiratory tumor motion is a major challenge in radiation therapy for thoracic and abdominal cancers. Effective motion management requires an accurate knowledge of the real-time tumor motion. External respiration monitoring devices (optical, etc) provide a noninvasive, non-ionizing, low-cost and practical approach to obtain the respiratory signal. Due to the highly complex and nonlinear relations between tumor and surrogate motion, its ultimate success hinges on the ability to accurately infer the tumor motion from respiratory surrogates. Given their widespread use in the clinic, such a method is critically needed. We propose to use a powerful memory-based learning method to find the complex relations between tumor motion and respiratory surrogates. The method first stores the training data in memory and then finds relevant data to answer a particular query. Nearby data points are assigned high relevance (or weights) and conversely distant data are assigned low relevance. By fitting relatively simple models to local patches instead of fitting one single global model, it is able to capture highly nonlinear and complex relations between the internal tumor motion and external surrogates accurately. Due to the local nature of weighting functions, the method is inherently robust to outliers in the training data. Moreover, both training and adapting to new data are performed almost instantaneously with memory-based learning, making it suitable for dynamically following variable internal/external relations. We evaluated the method using respiratory motion data from 11 patients. The data set consists of simultaneous measurement of 3D tumor motion and 1D abdominal surface (used as the surrogate signal in this study). There are a total of 171 respiratory traces, with an average peak-to-peak amplitude of ∼15 mm and average duration of ∼115 s per trace. Given only 5 s (roughly one breath) pretreatment training data, the method achieved an average 3D error of 1.5 mm and 95

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

Forecasting pulsatory motion for non-invasive cardiac radiosurgery: an analysis of algorithms from respiratory motion prediction.

Science.gov (United States)

Ernst, Floris; Bruder, Ralf; Schlaefer, Alexander; Schweikard, Achim

2011-01-01

Recently, radiosurgical treatment of cardiac arrhythmia, especially atrial fibrillation, has been proposed. Using the CyberKnife, focussed radiation will be used to create ablation lines on the beating heart to block unwanted electrical activity. Since this procedure requires high accuracy, the inevitable latency of the system (i.e., the robotic manipulator following the motion of the heart) has to be compensated for. We examine the applicability of prediction algorithms developed for respiratory motion prediction to the prediction of pulsatory motion. We evaluated the MULIN, nLMS, wLMS, SVRpred and EKF algorithms. The test data used has been recorded using external infrared position sensors, 3D ultrasound and the NavX catheter systems. With this data, we have shown that the error from latency can be reduced by at least 10 and as much as 75% (44% average), depending on the type of signal. It has also been shown that, although the SVRpred algorithm was successful in most cases, it was outperformed by the simple nLMS algorithm, the EKF or the wLMS algorithm in a number of cases. We have shown that prediction of cardiac motion is possible and that the algorithms known from respiratory motion prediction are applicable. Since pulsation is more regular than respiration, more research will have to be done to improve frequency-tracking algorithms, like the EKF method, which performed better than expected from their behaviour on respiratory motion traces.

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

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

Reduction of motion artifacts for PET imaging by respiratory correlated dynamic scanning

International Nuclear Information System (INIS)

Chuang, K.-S.; Chen, T.-J.; Chang, C.-C.; Wu, J.; Chen, S.; Wu, L.-C.; Liu, R.-S.

2006-01-01

Organ motion caused by respiration is a major challenge in positron emission tomography (PET) imaging. This work proposes a technique to reduce smearing in PET imaging caused by respiratory motion. Dynamic scanning at 1 frame/s is used. A point source, used as a marker, is attached to the object's abdomen during the scan. The source position in the projection view moves with respiratory motion and can be used to represent the respiratory phase within the time interval in which each frame data are acquired. One hundred and twenty frames are obtained for each study. The range of the positions of the marker is divided into four groups, representing different respiratory phases. The frames in which the organ positions (phases) are the same summed to produce a static sub-sinogram. Each sub-sinogram then undergoes regular image reconstruction to yield a motion-free image. The technique is applied to one volunteer under both free and coached breathing conditions. A parameter called the volume reduction factor is adopted to evaluate the effectiveness of this motion-reduction technique. The preliminary results indicate that the proposed technique effectively reduces motion artifacts in the image. Coached breathing yields better results than free breathing condition. The advantages of this method are that (1) the scanning time remains the same; (2) free breathing is allowed during the acquisition of the image; and (3) no user intervention is required

Simple motion correction strategy reduces respiratory-induced motion artifacts for k-t accelerated and compressed-sensing cardiovascular magnetic resonance perfusion imaging.

Science.gov (United States)

Zhou, Ruixi; Huang, Wei; Yang, Yang; Chen, Xiao; Weller, Daniel S; Kramer, Christopher M; Kozerke, Sebastian; Salerno, Michael

2018-02-01

Cardiovascular magnetic resonance (CMR) stress perfusion imaging provides important diagnostic and prognostic information in coronary artery disease (CAD). Current clinical sequences have limited temporal and/or spatial resolution, and incomplete heart coverage. Techniques such as k-t principal component analysis (PCA) or k-t sparcity and low rank structure (SLR), which rely on the high degree of spatiotemporal correlation in first-pass perfusion data, can significantly accelerate image acquisition mitigating these problems. However, in the presence of respiratory motion, these techniques can suffer from significant degradation of image quality. A number of techniques based on non-rigid registration have been developed. However, to first approximation, breathing motion predominantly results in rigid motion of the heart. To this end, a simple robust motion correction strategy is proposed for k-t accelerated and compressed sensing (CS) perfusion imaging. A simple respiratory motion compensation (MC) strategy for k-t accelerated and compressed-sensing CMR perfusion imaging to selectively correct respiratory motion of the heart was implemented based on linear k-space phase shifts derived from rigid motion registration of a region-of-interest (ROI) encompassing the heart. A variable density Poisson disk acquisition strategy was used to minimize coherent aliasing in the presence of respiratory motion, and images were reconstructed using k-t PCA and k-t SLR with or without motion correction. The strategy was evaluated in a CMR-extended cardiac torso digital (XCAT) phantom and in prospectively acquired first-pass perfusion studies in 12 subjects undergoing clinically ordered CMR studies. Phantom studies were assessed using the Structural Similarity Index (SSIM) and Root Mean Square Error (RMSE). In patient studies, image quality was scored in a blinded fashion by two experienced cardiologists. In the phantom experiments, images reconstructed with the MC strategy had higher

Real-time prediction of respiratory motion based on local regression methods

International Nuclear Information System (INIS)

Ruan, D; Fessler, J A; Balter, J M

2007-01-01

Recent developments in modulation techniques enable conformal delivery of radiation doses to small, localized target volumes. One of the challenges in using these techniques is real-time tracking and predicting target motion, which is necessary to accommodate system latencies. For image-guided-radiotherapy systems, it is also desirable to minimize sampling rates to reduce imaging dose. This study focuses on predicting respiratory motion, which can significantly affect lung tumours. Predicting respiratory motion in real-time is challenging, due to the complexity of breathing patterns and the many sources of variability. We propose a prediction method based on local regression. There are three major ingredients of this approach: (1) forming an augmented state space to capture system dynamics, (2) local regression in the augmented space to train the predictor from previous observation data using semi-periodicity of respiratory motion, (3) local weighting adjustment to incorporate fading temporal correlations. To evaluate prediction accuracy, we computed the root mean square error between predicted tumor motion and its observed location for ten patients. For comparison, we also investigated commonly used predictive methods, namely linear prediction, neural networks and Kalman filtering to the same data. The proposed method reduced the prediction error for all imaging rates and latency lengths, particularly for long prediction lengths

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

Effect of respiratory motion on internal radiation dosimetry

NARCIS (Netherlands)

Xie, Tianwu; Zaidi, Habib

2014-01-01

Purpose: Estimation of the radiation dose to internal organs is essential for the assessment of radiation risks and benefits to patients undergoing diagnostic and therapeutic nuclear medicine procedures including PET. Respiratory motion induces notable internal organ displacement, which influences

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

The internal-external respiratory motion correlation is unaffected by audiovisual biofeedback.

Science.gov (United States)

Steel, Harry; Pollock, Sean; Lee, Danny; Keall, Paul; Kim, Taeho

2014-03-01

This study evaluated if an audiovisual (AV) biofeedback causes variation in the level of external and internal correlation due to its interactive intervention in natural breathing. The internal (diaphragm) and external (abdominal wall) respiratory motion signals of 15 healthy human subjects under AV biofeedback and free breathing (FB) were analyzed and measures of correlation and regularity taken. Regularity metrics (root mean square error and spectral power dispersion metric) were obtained and the correlation between these metrics and the internal and external correlation was investigated. For FB and AV biofeedback assisted breathing the mean correlations found between internal and external respiratory motion were 0.96±0.02 and 0.96±0.03, respectively. This means there is no evidence to suggest (p-value=0.88) any difference in the correlation between internal and external respiratory motion with the use of AV biofeedback. Our results confirmed the hypothesis that the internal-external correlation with AV biofeedback is the same as for free breathing. Should this correlation be maintained for patients, AV biofeedback can be implemented in the clinic with confidence as regularity improvements using AV biofeedback with an external signal will be reflected in increased internal motion regularity.

Apparent diffusion coefficient measurement in a moving phantom simulating linear respiratory motion.

Science.gov (United States)

Kwee, Thomas C; Takahara, Taro; Muro, Isao; Van Cauteren, Marc; Imai, Yutaka; Nievelstein, Rutger A J; Mali, Willem P T M; Luijten, Peter R

2010-10-01

The aim of this study was to examine the effect of simulated linear respiratory motion on apparent diffusion coefficient (ADC) measurements. Six rectangular test tubes (14 × 92 mm) filled with either water, tomato ketchup, or mayonnaise were positioned in a box containing agarose gel. This box was connected to a double-acting pneumatic cylinder, capable of inducing periodic linear motion in the long-axis direction of the magnetic bore (23-mm stroke). Diffusion-weighted magnetic resonance imaging was performed for both the static and moving phantoms, and ADC measurements were made in the six test tubes in both situations. In the three test tubes whose long axes were parallel to the direction of motion, ADCs agreed well between the moving and static phantom situations. However, in two test tubes that were filled with fluids that had a considerably lower diffusion coefficient than the surrounding agarose gel, and whose long axes were perpendicular to the direction of motion, the ADCs agreed poorly between the moving and static phantom situations. ADC measurements of large homogeneous structures are not affected by linear respiratory motion. However, ADC measurements of inhomogeneous or small structures are affected by linear respiratory motion due to partial volume effects.

Apparent diffusion coefficient measurement in a moving phantom simulating linear respiratory motion

International Nuclear Information System (INIS)

Kwee, T.C.; Takahara, Taro; Nievelstein, R.A.J.; Mali, W.P.T.M.; Luijten, P.R.; Muro, Isao; Imai, Yutaka; Cauteren, M. Van

2010-01-01

The aim of this study was to examine the effect of simulated linear respiratory motion on apparent diffusion coefficient (ADC) measurements. Six rectangular test tubes (14 x 92 mm) filled with either water, tomato ketchup, or mayonnaise were positioned in a box containing agarose gel. This box was connected to a double-acting pneumatic cylinder, capable of inducing periodic linear motion in the long-axis direction of the magnetic bore (23-mm stroke). Diffusion-weighted magnetic resonance imaging was performed for both the static and moving phantoms, and ADC measurements were made in the six test tubes in both situations. In the three test tubes whose long axes were parallel to the direction of motion, ADCs agreed well between the moving and static phantom situations. However, in two test tubes that were filled with fluids that had a considerably lower diffusion coefficient than the surrounding agarose gel, and whose long axes were perpendicular to the direction of motion, the ADCs agreed poorly between the moving and static phantom situations. ADC measurements of large homogeneous structures are not affected by linear respiratory motion. However, ADC measurements of inhomogeneous or small structures are affected by linear respiratory motion due to partial volume effects. (author)

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

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

4D modeling and estimation of respiratory motion for radiation therapy

CERN Document Server

Lorenz, Cristian

2013-01-01

Respiratory motion causes an important uncertainty in radiotherapy planning of the thorax and upper abdomen. The main objective of radiation therapy is to eradicate or shrink tumor cells without damaging the surrounding tissue by delivering a high radiation dose to the tumor region and a dose as low as possible to healthy organ tissues. Meeting this demand remains a challenge especially in case of lung tumors due to breathing-induced tumor and organ motion where motion amplitudes can measure up to several centimeters. Therefore, modeling of respiratory motion has become increasingly important in radiation therapy. With 4D imaging techniques spatiotemporal image sequences can be acquired to investigate dynamic processes in the patient’s body. Furthermore, image registration enables the estimation of the breathing-induced motion and the description of the temporal change in position and shape of the structures of interest by establishing the correspondence between images acquired at different phases of the br...

Effectiveness of external respiratory surrogates for in vivo liver motion estimation

International Nuclear Information System (INIS)

Chang, Kai-Hsiang; Ho, Ming-Chih; Yeh, Chi-Chuan; Chen, Yu-Chien; Lian, Feng-Li; Lin, Win-Li; Yen, Jia-Yush; Chen, Yung-Yaw

2012-01-01

Purpose: Due to low frame rate of MRI and high radiation damage from fluoroscopy and CT, liver motion estimation using external respiratory surrogate signals seems to be a better approach to track liver motion in real-time for liver tumor treatments in radiotherapy and thermotherapy. This work proposes a liver motion estimation method based on external respiratory surrogate signals. Animal experiments are also conducted to investigate related issues, such as the sensor arrangement, multisensor fusion, and the effective time period. Methods: Liver motion and abdominal motion are both induced by respiration and are proved to be highly correlated. Contrary to the difficult direct measurement of the liver motion, the abdominal motion can be easily accessed. Based on this idea, our study is split into the model-fitting stage and the motion estimation stage. In the first stage, the correlation between the surrogates and the liver motion is studied and established via linear regression method. In the second stage, the liver motion is estimated by the surrogate signals with the correlation model. Animal experiments on cases of single surrogate signal, multisurrogate signals, and long-term surrogate signals are conducted and discussed to verify the practical use of this approach. Results: The results show that the best single sensor location is at the middle of the upper abdomen, while multisurrogate models are generally better than the single ones. The estimation error is reduced from 0.6 mm for the single surrogate models to 0.4 mm for the multisurrogate models. The long-term validity of the estimation models is quite satisfactory within the period of 10 min with the estimation error less than 1.4 mm. Conclusions: External respiratory surrogate signals from the abdomen motion produces good performance for liver motion estimation in real-time. Multisurrogate signals enhance estimation accuracy, and the estimation model can maintain its accuracy for at least 10 min. This

Investigating the influence of respiratory motion on the radiation induced bystander effect in modulated radiotherapy

Science.gov (United States)

Cole, Aidan J.; McGarry, Conor K.; Butterworth, Karl T.; McMahon, Stephen J.; Hounsell, Alan R.; Prise, Kevin M.; O'Sullivan, Joe M.

2013-12-01

Respiratory motion introduces complex spatio-temporal variations in the dosimetry of radiotherapy and may contribute towards uncertainties in radiotherapy planning. This study investigates the potential radiobiological implications occurring due to tumour motion in areas of geometric miss in lung cancer radiotherapy. A bespoke phantom and motor-driven platform to replicate respiratory motion and study the consequences on tumour cell survival in vitro was constructed. Human non-small-cell lung cancer cell lines H460 and H1299 were irradiated in modulated radiotherapy configurations in the presence and absence of respiratory motion. Clonogenic survival was calculated for irradiated and shielded regions. Direction of motion, replication of dosimetry by multi-leaf collimator (MLC) manipulation and oscillating lead shielding were investigated to confirm differences in cell survival. Respiratory motion was shown to significantly increase survival for out-of-field regions for H460/H1299 cell lines when compared with static irradiation (p < 0.001). Significantly higher survival was found in the in-field region for the H460 cell line (p < 0.030). Oscillating lead shielding also produced these significant differences. Respiratory motion and oscillatory delivery of radiation dose to human tumour cells has a significant impact on in- and out-of-field survival in the presence of non-uniform irradiation in this in vitro set-up. This may have important radiobiological consequences for modulated radiotherapy in lung cancer.

Smoothing of respiratory motion traces for motion-compensated radiotherapy.

Science.gov (United States)

Ernst, Floris; Schlaefer, Alexander; Schweikard, Achim

2010-01-01

The CyberKnife system has been used successfully for several years to radiosurgically treat tumors without the need for stereotactic fixation or sedation of the patient. It has been shown that tumor motion in the lung, liver, and pancreas can be tracked with acceptable accuracy and repeatability. However, highly precise targeting for tumors in the lower abdomen, especially for tumors which exhibit strong motion, remains problematic. Reasons for this are manifold, like the slow tracking system operating at 26.5 Hz, and using the signal from the tracking camera "as is." Since the motion recorded with the camera is used to compensate for system latency by prediction and the predicted signal is subsequently used to infer the tumor position from a correlation model based on x-ray imaging of gold fiducials around the tumor, camera noise directly influences the targeting accuracy. The goal of this work is to establish the suitability of a new smoothing method for respiratory motion traces used in motion-compensated radiotherapy. The authors endeavor to show that better prediction--With a lower rms error of the predicted signal--and/or smoother prediction is possible using this method. The authors evaluated six commercially available tracking systems (NDI Aurora, PolarisClassic, Polaris Vicra, MicronTracker2 H40, FP5000, and accuTrack compact). The authors first tracked markers both stationary and while in motion to establish the systems' noise characteristics. Then the authors applied a smoothing method based on the a trous wavelet decomposition to reduce the devices' noise level. Additionally, the smoothed signal of the moving target and a motion trace from actual human respiratory motion were subjected to prediction using the MULIN and the nLMS2 algorithms. The authors established that the noise distribution for a static target is Gaussian and that when the probe is moved such as to mimic human respiration, it remains Gaussian with the exception of the FP5000 and the

Smoothing of respiratory motion traces for motion-compensated radiotherapy

International Nuclear Information System (INIS)

Ernst, Floris; Schlaefer, Alexander; Schweikard, Achim

2010-01-01

Purpose: The CyberKnife system has been used successfully for several years to radiosurgically treat tumors without the need for stereotactic fixation or sedation of the patient. It has been shown that tumor motion in the lung, liver, and pancreas can be tracked with acceptable accuracy and repeatability. However, highly precise targeting for tumors in the lower abdomen, especially for tumors which exhibit strong motion, remains problematic. Reasons for this are manifold, like the slow tracking system operating at 26.5 Hz, and using the signal from the tracking camera ''as is''. Since the motion recorded with the camera is used to compensate for system latency by prediction and the predicted signal is subsequently used to infer the tumor position from a correlation model based on x-ray imaging of gold fiducials around the tumor, camera noise directly influences the targeting accuracy. The goal of this work is to establish the suitability of a new smoothing method for respiratory motion traces used in motion-compensated radiotherapy. The authors endeavor to show that better prediction--With a lower rms error of the predicted signal--and/or smoother prediction is possible using this method. Methods: The authors evaluated six commercially available tracking systems (NDI Aurora, PolarisClassic, Polaris Vicra, MicronTracker2 H40, FP5000, and accuTrack compact). The authors first tracked markers both stationary and while in motion to establish the systems' noise characteristics. Then the authors applied a smoothing method based on the a trous wavelet decomposition to reduce the devices' noise level. Additionally, the smoothed signal of the moving target and a motion trace from actual human respiratory motion were subjected to prediction using the MULIN and the nLMS 2 algorithms. Results: The authors established that the noise distribution for a static target is Gaussian and that when the probe is moved such as to mimic human respiration, it remains Gaussian with the

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

Technical note: Correlation of respiratory motion between external patient surface and internal anatomical landmarks

Science.gov (United States)

Fayad, Hadi; Pan, Tinsu; Clément, Jean-François; Visvikis, Dimitris

2011-01-01

Purpose Current respiratory motion monitoring devices used for motion synchronization in medical imaging and radiotherapy provide either 1D respiratory signals over a specific region or 3D information based on few external or internal markers. On the other hand, newer technology may offer the potential to monitor the entire patient external surface in real time. The main objective of this study was to assess the motion correlation between such an external patient surface and internal anatomical landmarks motion. Methods Four dimensional Computed Tomography (4D CT) volumes for ten patients were used in this study. Anatomical landmarks were manually selected in the thoracic region across the 4D CT datasets by two experts. The landmarks included normal structures as well as the tumour location. In addition, a distance map representing the entire external patient surface, which corresponds to surfaces acquired by a Time of Flight (ToF) camera or similar devices, was created by segmenting the skin of all 4D CT volumes using a thresholding algorithm. Finally, the correlation between the internal landmarks and external surface motion was evaluated for different regions (placement and size) throughout a patient’s surface. Results Significant variability was observed in the motion of the different parts of the external patient surface. The larger motion magnitude was consistently measured in the central regions of the abdominal and the thoracic areas for the different patient datasets considered. The highest correlation coefficients were observed between the motion of these external surface areas and internal landmarks such as the diaphragm and mediastinum structures as well as the tumour location landmarks (0.8 ± 0.18 and 0.72 ± 0.12 for the abdominal and the thoracic regions respectively). Worse correlation was observed when one considered landmarks not significantly influenced by respiratory motion such as the apex and the sternum. Discussion and conclusions There

Fast Numerical Simulation of Focused Ultrasound Treatments During Respiratory Motion With Discontinuous Motion Boundaries.

Science.gov (United States)

Schwenke, Michael; Georgii, Joachim; Preusser, Tobias

2017-07-01

Focused ultrasound (FUS) is rapidly gaining clinical acceptance for several target tissues in the human body. Yet, treating liver targets is not clinically applied due to a high complexity of the procedure (noninvasiveness, target motion, complex anatomy, blood cooling effects, shielding by ribs, and limited image-based monitoring). To reduce the complexity, numerical FUS simulations can be utilized for both treatment planning and execution. These use-cases demand highly accurate and computationally efficient simulations. We propose a numerical method for the simulation of abdominal FUS treatments during respiratory motion of the organs and target. Especially, a novel approach is proposed to simulate the heating during motion by solving Pennes' bioheat equation in a computational reference space, i.e., the equation is mathematically transformed to the reference. The approach allows for motion discontinuities, e.g., the sliding of the liver along the abdominal wall. Implementing the solver completely on the graphics processing unit and combining it with an atlas-based ultrasound simulation approach yields a simulation performance faster than real time (less than 50-s computing time for 100 s of treatment time) on a modern off-the-shelf laptop. The simulation method is incorporated into a treatment planning demonstration application that allows to simulate real patient cases including respiratory motion. The high performance of the presented simulation method opens the door to clinical applications. The methods bear the potential to enable the application of FUS for moving organs.

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.

SU-G-JeP1-14: Respiratory Motion Tracking Using Kinect V2

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Silverstein, E; Snyder, M [Wayne State University, Detroit, MI (United States)

2016-06-15

Purpose: Investigate capability and accuracy of Kinect v2 camera for tracking respiratory motion to use as a tool during 4DCT or in combination with motion management during radiotherapy treatments. Methods: Utilizing the depth sensor on the Kinect as well as code written in C#, the respiratory motion of a patient was tracked by recording the depth (distance) values obtained at several points on the patient. Respiratory traces were also obtained using Varian’s RPM system, which traces the movement of a propriety marker placed on the patient’s abdomen, as well as an Anzai belt, which utilizes a pressure sensor to track respiratory motion. With the Kinect mounted 60 cm above the patient and pointing straight down, 11 breathing cycles were recorded with each system simultaneously. Relative displacement values during this time period were saved to file. While RPM and the Kinect give displacement values in distance units, the Anzai system has arbitrary units. As such, displacement for all three are displayed relative to the maximum value for the time interval from that system. Additional analysis was performed between RPM and Kinect for absolute displacement values. Results: Analysis of the data from all three systems indicates the relative motion obtained from the Kinect is both accurate and in sync with the data from RPM and Anzai. The absolute displacement data from RPM and Kinect show similar displacement values throughout the acquisition except for the depth obtained from the Kinect during maximum exhalation (largest distance from Kinect). Conclusion: By simply utilizing the depth data of specific points on a patient obtained from the Kinect, respiratory motion can be tracked and visualized with accuracy comparable to that of the Varian RPM and Anzai belt.

Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer

DEFF Research Database (Denmark)

Sloth Møller, Ditte; Knap, Marianne Marquard; Nyeng, Tine Bisballe

2017-01-01

: PTVσ yields the smallest volumes but does not ensure coverage of tumor during the full respiratory motion due to tumor deformation. Incorporating the respiratory motion in the delineation (PTVdel) takes into account the entire respiratory cycle including deformation, but at the cost, however, of larger...

Utilize target motion to cover clinical target volume (ctv) - a novel and practical treatment planning approach to manage respiratory motion

International Nuclear Information System (INIS)

Jin Jianyue; Ajlouni, Munther; Kong Fengming; Ryu, Samuel; Chetty, Indrin J.; Movsas, Benjamin

2008-01-01

Purpose: To use probability density function (PDF) to model motion effects and incorporate this information into treatment planning for lung cancers. Material and methods: PDFs were calculated from the respiratory motion traces of 10 patients. Motion effects were evaluated by convolving static dose distributions with various PDFs. Based on a differential dose prescription with relatively lower dose to the clinical target volume (CTV) than to the gross tumor volume (GTV), two approaches were proposed to incorporate PDFs into treatment planning. The first approach uses the GTV-based internal target volume (ITV) as the planning target volume (PTV) to ensure full dose to the GTV, and utilizes the motion-induced dose gradient to cover the CTV. The second approach employs an inhomogeneous static dose distribution within a minimized PTV to best match the prescription dose gradient. Results: Motion effects on dose distributions were minimal in the anterior-posterior (AP) and lateral directions: a 10-mm motion only induced about 3% of dose reduction in the peripheral target region. The motion effect was remarkable in the cranial-caudal direction. It varied with the motion amplitude, but tended to be similar for various respiratory patterns. For the first approach, a 10-15 mm motion would adequately cover the CTV (presumed to be 60-70% of the GTV dose) without employing the CTV in planning. For motions 15-mm. An example of inhomogeneous static dose distribution in a reduced PTV was given, and it showed significant dose reduction in the normal tissue without compromising target coverage. Conclusions: Respiratory motion-induced dose gradient can be utilized to cover the CTV and minimize the lung dose without the need for more sophisticated technologies

Optimizing 4-Dimensional Magnetic Resonance Imaging Data Sampling for Respiratory Motion Analysis of Pancreatic Tumors

Energy Technology Data Exchange (ETDEWEB)

Stemkens, Bjorn, E-mail: b.stemkens@umcutrecht.nl [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands); Tijssen, Rob H.N. [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands); Senneville, Baudouin D. de [Imaging Division, University Medical Center Utrecht, Utrecht (Netherlands); L' Institut de Mathématiques de Bordeaux, Unité Mixte de Recherche 5251, Centre National de la Recherche Scientifique/University of Bordeaux, Bordeaux (France); Heerkens, Hanne D.; Vulpen, Marco van; Lagendijk, Jan J.W.; Berg, Cornelis A.T. van den [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands)

2015-03-01

Purpose: To determine the optimum sampling strategy for retrospective reconstruction of 4-dimensional (4D) MR data for nonrigid motion characterization of tumor and organs at risk for radiation therapy purposes. Methods and Materials: For optimization, we compared 2 surrogate signals (external respiratory bellows and internal MRI navigators) and 2 MR sampling strategies (Cartesian and radial) in terms of image quality and robustness. Using the optimized protocol, 6 pancreatic cancer patients were scanned to calculate the 4D motion. Region of interest analysis was performed to characterize the respiratory-induced motion of the tumor and organs at risk simultaneously. Results: The MRI navigator was found to be a more reliable surrogate for pancreatic motion than the respiratory bellows signal. Radial sampling is most benign for undersampling artifacts and intraview motion. Motion characterization revealed interorgan and interpatient variation, as well as heterogeneity within the tumor. Conclusions: A robust 4D-MRI method, based on clinically available protocols, is presented and successfully applied to characterize the abdominal motion in a small number of pancreatic cancer patients.

Very long baseline interferometry applied to polar motion, relativity, and geodesy. Ph.D. thesis

International Nuclear Information System (INIS)

Ma, C.

1978-01-01

The causes and effects of diurnal polar motion are described. An algorithm was developed for modeling the effects on very long baseline interferometry observables. A selection was made between two three-station networks for monitoring polar motion. The effects of scheduling and the number of sources observed on estimated baseline errors are discussed. New hardware and software techniques in very long baseline interferometry are described

Image quality of cone beam CT on respiratory motion

International Nuclear Information System (INIS)

Zhang Ke; Li Minghui; Dai Jianrong; Wang Shi

2011-01-01

In this study,the influence of respiratory motion on Cone Beam CT (CBCT) image quality was investigated by a motion simulating platform, an image quality phantom, and a kV X-ray CBCT. A total of 21 motion states in the superior-inferior direction and the anterior-posterior direction, separately or together, was simulated by considering different respiration amplitudes, periods and hysteresis. The influence of motion on CBCT image quality was evaluated with the quality indexes of low contrast visibility, geometric accuracy, spatial resolution and uniformity of CT values. The results showed that the quality indexes were affected by the motion more prominently in AP direction than in SI direction, and the image quality was affected by the respiration amplitude more prominently than the respiration period and the hysteresis. The CBCT image quality and its characteristics influenced by the respiration motion, and may be exploited in finding solutions. (authors)

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

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.

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.

Characterization of respiratory and cardiac motion from electro-anatomical mapping data for improved fusion of MRI to left ventricular electrograms.

Directory of Open Access Journals (Sweden)

Sébastien Roujol

Full Text Available Accurate fusion of late gadolinium enhancement magnetic resonance imaging (MRI and electro-anatomical voltage mapping (EAM is required to evaluate the potential of MRI to identify the substrate of ventricular tachycardia. However, both datasets are not acquired at the same cardiac phase and EAM data is corrupted with respiratory motion limiting the accuracy of current rigid fusion techniques. Knowledge of cardiac and respiratory motion during EAM is thus required to enhance the fusion process. In this study, we propose a novel approach to characterize both cardiac and respiratory motion from EAM data using the temporal evolution of the 3D catheter location recorded from clinical EAM systems. Cardiac and respiratory motion components are extracted from the recorded catheter location using multi-band filters. Filters are calibrated for each EAM point using estimates of heart rate and respiratory rate. The method was first evaluated in numerical simulations using 3D models of cardiac and respiratory motions of the heart generated from real time MRI data acquired in 5 healthy subjects. An accuracy of 0.6-0.7 mm was found for both cardiac and respiratory motion estimates in numerical simulations. Cardiac and respiratory motions were then characterized in 27 patients who underwent LV mapping for treatment of ventricular tachycardia. Mean maximum amplitude of cardiac and respiratory motion was 10.2±2.7 mm (min = 5.5, max = 16.9 and 8.8±2.3 mm (min = 4.3, max = 14.8, respectively. 3D Cardiac and respiratory motions could be estimated from the recorded catheter location and the method does not rely on additional imaging modality such as X-ray fluoroscopy and can be used in conventional electrophysiology laboratory setting.

Reproducible simulation of respiratory motion in porcine lung explants

Energy Technology Data Exchange (ETDEWEB)

Biederer, J. [Dept. of Diagnostic Radiology, Univ. Hospital Schleswig-Holstein, Campus Kiel (Germany); Dept. of Radiology, German Cancer Research Center, Heidelberg (Germany); Plathow, C. [Dept. of Diagnostic Radiology, Eberhard-Karls-Univ. Tuebingen (Germany); Dept. of Radiology, German Cancer Research Center, Heidelberg (Germany); Schoebinger, M.; Meinzer, H.P. [Dept. of Medical and Biological Informatics, German Cancer Research Center, Heidelberg (Germany); Tetzlaff, R.; Puderbach, M.; Zaporozhan, J.; Kauczor, H.U. [Dept. of Radiology, German Cancer Research Center, Heidelberg (Germany); Bolte, H.; Heller, M. [Dept. of Diagnostic Radiology, Univ. Hospital Schleswig-Holstein, Campus Kiel (Germany)

2006-11-15

Purpose: To develop a model for exactly reproducible respiration motion simulations of animal lung explants inside an MR-compatible chest phantom. Materials and Methods: The materials included a piston pump and a flexible silicone reconstruction of a porcine diaphragm and were used in combination with an established MR-compatible chest phantom for porcine heart-lung preparations. The rhythmic inflation and deflation of the diaphragm at the bottom of the artificial thorax with water (1-1.5 L) induced lung tissue displacement resembling diaphragmatic breathing. This system was tested on five porcine heart-lung preparations using 1.5T MRI with transverse and coronal 3D-GRE (TR/TE=3.63/1.58, 256 x 256 matrix, 350 mm FOV, 4 mm slices) and half Fourier T2-FSE (TR/TE=545/29, 256 x 192, 350 mm, 6 mm) as well as multiple row detector CT (16 x 1 mm collimation, pitch 1.5, FOV 400 mm, 120 mAs) acquired at five fixed inspiration levels. Dynamic CT scans and coronal MRI with dynamic 2D-GRE and 2D-SS-GRE sequences (image frequencies of 10/sec and 3/sec, respectively) were acquired during continuous 'breathing' (7/minute). The position of the piston pump was visually correlated with the respiratory motion visible through the transparent wall of the phantom and with dynamic displays of CT and MR images. An elastic body splines analysis of the respiratory motion was performed using CT data. Results: Visual evaluation of MRI and CT showed three-dimensional movement of the lung tissue throughout the respiration cycle. Local tissue displacement inside the lung explants was documented with motion maps calculated from CT. The maximum displacement at the top of the diaphragm (mean 26.26 [SD 1.9] mm on CT and 27.16 [SD 1.5] mm on MRI, respectively [p=0.25; Wilcoxon test]) was in the range of tidal breathing in human patients. Conclusion: The chest phantom with a diaphragmatic pump is a promising platform for multi-modality imaging studies of the effects of respiratory lung

Reproducible simulation of respiratory motion in porcine lung explants

International Nuclear Information System (INIS)

Biederer, J.; Plathow, C.; Schoebinger, M.; Meinzer, H.P.; Tetzlaff, R.; Puderbach, M.; Zaporozhan, J.; Kauczor, H.U.; Bolte, H.; Heller, M.

2006-01-01

Purpose: To develop a model for exactly reproducible respiration motion simulations of animal lung explants inside an MR-compatible chest phantom. Materials and Methods: The materials included a piston pump and a flexible silicone reconstruction of a porcine diaphragm and were used in combination with an established MR-compatible chest phantom for porcine heart-lung preparations. The rhythmic inflation and deflation of the diaphragm at the bottom of the artificial thorax with water (1-1.5 L) induced lung tissue displacement resembling diaphragmatic breathing. This system was tested on five porcine heart-lung preparations using 1.5T MRI with transverse and coronal 3D-GRE (TR/TE=3.63/1.58, 256 x 256 matrix, 350 mm FOV, 4 mm slices) and half Fourier T2-FSE (TR/TE=545/29, 256 x 192, 350 mm, 6 mm) as well as multiple row detector CT (16 x 1 mm collimation, pitch 1.5, FOV 400 mm, 120 mAs) acquired at five fixed inspiration levels. Dynamic CT scans and coronal MRI with dynamic 2D-GRE and 2D-SS-GRE sequences (image frequencies of 10/sec and 3/sec, respectively) were acquired during continuous 'breathing' (7/minute). The position of the piston pump was visually correlated with the respiratory motion visible through the transparent wall of the phantom and with dynamic displays of CT and MR images. An elastic body splines analysis of the respiratory motion was performed using CT data. Results: Visual evaluation of MRI and CT showed three-dimensional movement of the lung tissue throughout the respiration cycle. Local tissue displacement inside the lung explants was documented with motion maps calculated from CT. The maximum displacement at the top of the diaphragm (mean 26.26 [SD 1.9] mm on CT and 27.16 [SD 1.5] mm on MRI, respectively [p=0.25; Wilcoxon test]) was in the range of tidal breathing in human patients. Conclusion: The chest phantom with a diaphragmatic pump is a promising platform for multi-modality imaging studies of the effects of respiratory lung motion. (orig.)

Respiratory motion artefacts in dynamic liver MRI: a comparison using gadoxetate disodium and gadobutrol

Energy Technology Data Exchange (ETDEWEB)

Luetkens, Julian A.; Kupczyk, Patrick A.; Doerner, Jonas; Willinek, Winfried A.; Schild, Hans H.; Kukuk, Guido M. [University of Bonn, Department of Radiology, Bonn (Germany); Fimmers, Rolf [University of Bonn, Department of Medical Biometry, Informatics, and Epidemiology, Bonn (Germany)

2015-11-15

Our aim was to retrospectively evaluate the occurrence of respiratory motion artefacts in patients undergoing dynamic liver magnetic resonance (MR) either with gadoxetate disodium or gadobutrol. Two hundred and thirty liver MR studies (115 with gadobutrol, 115 with gadoxetate disodium) were analysed. Respiratory motion artefacts on dynamic 3D T1-weighted MR images (pre-contrast, arterial, venous, and late-dynamic phase) were assessed using a five-point rating scale. Severe motion was defined as a score ≥ 4. Mean motion scores were compared with the Mann-Whitney-U-test. The chi-squared-test was used for dichotomous comparisons. Mean motion scores for gadoxetate disodium and gadobutrol showed no relevant differences for each phase of the dynamic contrast series (pre-contrast: 1.85 ± 0.70 vs. 1.88 ± 0.57, arterial: 1.85 ± 0.81 vs. 1.87 ± 0.74, venous: 1.82 ± 0.67 vs. 1.74 ± 0.64, late-dynamic: 1.75 ± 0.62 vs. 1.79 ± 0.63; p = 0.469, 0.557, 0.382 and 0.843, respectively). Severe motion artefacts had a similar incidence using gadoxetate disodium and gadobutrol (11/460 [2.4 %] vs. 7/460 [1.5 %]; p = 0.341). Gadoxetate disodium is associated with equivalent motion scores compared to gadobutrol in dynamic liver MRI. In addition, both contrast agents demonstrated a comparable and acceptable rate of severe respiratory motion artefacts. (orig.)

Non-model-based correction of respiratory motion using beat-to-beat 3D spiral fat-selective imaging.

Science.gov (United States)

Keegan, Jennifer; Gatehouse, Peter D; Yang, Guang-Zhong; Firmin, David N

2007-09-01

To demonstrate the feasibility of retrospective beat-to-beat correction of respiratory motion, without the need for a respiratory motion model. A high-resolution three-dimensional (3D) spiral black-blood scan of the right coronary artery (RCA) of six healthy volunteers was acquired over 160 cardiac cycles without respiratory gating. One spiral interleaf was acquired per cardiac cycle, prior to each of which a complete low-resolution fat-selective 3D spiral dataset was acquired. The respiratory motion (3D translation) on each cardiac cycle was determined by cross-correlating a region of interest (ROI) in the fat around the artery in the low-resolution datasets with that on a reference end-expiratory dataset. The measured translations were used to correct the raw data of the high-resolution spiral interleaves. Beat-to-beat correction provided consistently good results, with the image quality being better than that obtained with a fixed superior-inferior tracking factor of 0.6 and better than (N = 5) or equal to (N = 1) that achieved using a subject-specific retrospective 3D translation motion model. Non-model-based correction of respiratory motion using 3D spiral fat-selective imaging is feasible, and in this small group of volunteers produced better-quality images than a subject-specific retrospective 3D translation motion model. (c) 2007 Wiley-Liss, Inc.

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.

SU-E-J-192: Comparative Effect of Different Respiratory Motion Management Systems

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Y; Kadoya, N; Ito, K; Kanai, T; Jingu, K [Tohoku University School of Medicine, Sendai, Miyagi (Japan); Kida, S [Tohoku University Hospital, Sendai City, Miyagi (Japan); Kishi, K; Sato, K [Tohoku University Hospital, Sendai, Miyagi (Japan); Dobashi, S; Takeda, K [Tohoku University, Sendai, Miyagi (Japan)

2015-06-15

Purpose: Irregular breathing can influence the outcome of four-dimensional computed tomography imaging for causing artifacts. Audio-visual biofeedback systems associated with patient-specific guiding waveform are known to reduce respiratory irregularities. In Japan, abdomen and chest motion self-control devices (Abches), representing simpler visual coaching techniques without guiding waveform are used instead; however, no studies have compared these two systems to date. Here, we evaluate the effectiveness of respiratory coaching to reduce respiratory irregularities by comparing two respiratory management systems. Methods: We collected data from eleven healthy volunteers. Bar and wave models were used as audio-visual biofeedback systems. Abches consisted of a respiratory indicator indicating the end of each expiration and inspiration motion. Respiratory variations were quantified as root mean squared error (RMSE) of displacement and period of breathing cycles. Results: All coaching techniques improved respiratory variation, compared to free breathing. Displacement RMSEs were 1.43 ± 0.84, 1.22 ± 1.13, 1.21 ± 0.86, and 0.98 ± 0.47 mm for free breathing, Abches, bar model, and wave model, respectively. Free breathing and wave model differed significantly (p < 0.05). Period RMSEs were 0.48 ± 0.42, 0.33 ± 0.31, 0.23 ± 0.18, and 0.17 ± 0.05 s for free breathing, Abches, bar model, and wave model, respectively. Free breathing and all coaching techniques differed significantly (p < 0.05). For variation in both displacement and period, wave model was superior to free breathing, bar model, and Abches. The average reduction in displacement and period RMSE compared with wave model were 27% and 47%, respectively. Conclusion: The efficacy of audio-visual biofeedback to reduce respiratory irregularity compared with Abches. Our results showed that audio-visual biofeedback combined with a wave model can potentially provide clinical benefits in respiratory management

SU-E-J-192: Comparative Effect of Different Respiratory Motion Management Systems

International Nuclear Information System (INIS)

Nakajima, Y; Kadoya, N; Ito, K; Kanai, T; Jingu, K; Kida, S; Kishi, K; Sato, K; Dobashi, S; Takeda, K

2015-01-01

Purpose: Irregular breathing can influence the outcome of four-dimensional computed tomography imaging for causing artifacts. Audio-visual biofeedback systems associated with patient-specific guiding waveform are known to reduce respiratory irregularities. In Japan, abdomen and chest motion self-control devices (Abches), representing simpler visual coaching techniques without guiding waveform are used instead; however, no studies have compared these two systems to date. Here, we evaluate the effectiveness of respiratory coaching to reduce respiratory irregularities by comparing two respiratory management systems. Methods: We collected data from eleven healthy volunteers. Bar and wave models were used as audio-visual biofeedback systems. Abches consisted of a respiratory indicator indicating the end of each expiration and inspiration motion. Respiratory variations were quantified as root mean squared error (RMSE) of displacement and period of breathing cycles. Results: All coaching techniques improved respiratory variation, compared to free breathing. Displacement RMSEs were 1.43 ± 0.84, 1.22 ± 1.13, 1.21 ± 0.86, and 0.98 ± 0.47 mm for free breathing, Abches, bar model, and wave model, respectively. Free breathing and wave model differed significantly (p < 0.05). Period RMSEs were 0.48 ± 0.42, 0.33 ± 0.31, 0.23 ± 0.18, and 0.17 ± 0.05 s for free breathing, Abches, bar model, and wave model, respectively. Free breathing and all coaching techniques differed significantly (p < 0.05). For variation in both displacement and period, wave model was superior to free breathing, bar model, and Abches. The average reduction in displacement and period RMSE compared with wave model were 27% and 47%, respectively. Conclusion: The efficacy of audio-visual biofeedback to reduce respiratory irregularity compared with Abches. Our results showed that audio-visual biofeedback combined with a wave model can potentially provide clinical benefits in respiratory management

Control of Respiratory Motion by Hypnosis Intervention during Radiotherapy of Lung Cancer I

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Rongmao Li

2013-01-01

Full Text Available The uncertain position of lung tumor during radiotherapy compromises the treatment effect. To effectively control respiratory motion during radiotherapy of lung cancer without any side effects, a novel control scheme, hypnosis, has been introduced in lung cancer treatment. In order to verify the suggested method, six volunteers were selected with a wide range of distribution of age, weight, and chest circumference. A set of experiments have been conducted for each volunteer, under the guidance of the professional hypnotist. All the experiments were repeated in the same environmental condition. The amplitude of respiration has been recorded under the normal state and hypnosis, respectively. Experimental results show that the respiration motion of volunteers in hypnosis has smaller and more stable amplitudes than in normal state. That implies that the hypnosis intervention can be an alternative way for respiratory control, which can effectively reduce the respiratory amplitude and increase the stability of respiratory cycle. The proposed method will find useful application in image-guided radiotherapy.

Control of Respiratory Motion by Hypnosis Intervention during Radiotherapy of Lung Cancer I

Science.gov (United States)

Deng, Jie; Xie, Yaoqin

2013-01-01

The uncertain position of lung tumor during radiotherapy compromises the treatment effect. To effectively control respiratory motion during radiotherapy of lung cancer without any side effects, a novel control scheme, hypnosis, has been introduced in lung cancer treatment. In order to verify the suggested method, six volunteers were selected with a wide range of distribution of age, weight, and chest circumference. A set of experiments have been conducted for each volunteer, under the guidance of the professional hypnotist. All the experiments were repeated in the same environmental condition. The amplitude of respiration has been recorded under the normal state and hypnosis, respectively. Experimental results show that the respiration motion of volunteers in hypnosis has smaller and more stable amplitudes than in normal state. That implies that the hypnosis intervention can be an alternative way for respiratory control, which can effectively reduce the respiratory amplitude and increase the stability of respiratory cycle. The proposed method will find useful application in image-guided radiotherapy. PMID:24093100

SU-F-I-15: Evaluation of a New MR-Compatible Respiratory Motion Device at 3T

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Soliman, A [Sunnybrook Research Institute, Toronto, ON (Canada); Sunnybrook Health Sciences Centre, Toronto, ON (Canada); Chugh, B; Keller, B [Sunnybrook Health Sciences Centre, Toronto, ON (Canada); University of Toronto, Toronto, ON (Canada); Sahgal, A; Song, W [Sunnybrook Research Institute, Toronto, ON (Canada); Sunnybrook Health Sciences Centre, Toronto, ON (Canada); University of Toronto, Toronto, ON (Canada)

2016-06-15

Purpose: Recent advances in MRI-guided radiotherapy has inspired the development of MRI-compatible motion devices that simulate patient periodic motion in the scanner, particularly respiratory motion. Most commercial devices rely on non MR-safe ferromagnetic stepper motors which are not practical for regular QA testing. This work evaluates the motion performance of a new fully MRI compatible respiratory motion device at 3T. Methods: The QUASAR™ MRI-compatible respiratory motion phantom has been recently developed by Modus QA Inc., London, ON, Canada. The prototype is constructed from diamagnetic materials with linear motion generated using MRI-compatible piezoelectric motors that can be safely inserted in the scanner bore. The tumor was represented by a fillable sphere and is attached to the linear motion generator. The spherical tumor-representative and its surroundings were filled with different concentrations of MnCl2 to produce realistic relaxation times. The motion was generated along the longitudinal (H/F) axis of the bore using sinusoidal reference waveform (amplitude = 15 mm, frequency 0.25 Hz). Imaging was then performed on 3T Philips Achieva using a 32-channel cardiac coil. Fast 2D spoiled gradient-echo was used with a spatial resolution of 1.8 × 1.8 mm{sup 2} and slice thickness of 4 mm. The motion waveform was then measured on the resultant image series by tracking the centroid of the sphere through the time series. This image-derived measured motion was compared to the software-generated reference waveform. Results: No visible distortions from the device were observed on the images. Excellent agreement between the measured and the reference waveforms were obtained. Negligible motion was observed in the lateral (R/L) direction. Conclusion: Our investigation demonstrates that this piezo-electric motor design is effective at simulating periodic motion and is a potential candidate for MRI-radiotherapy respiratory motion simulation. Future work should

SU-F-I-15: Evaluation of a New MR-Compatible Respiratory Motion Device at 3T

International Nuclear Information System (INIS)

Soliman, A; Chugh, B; Keller, B; Sahgal, A; Song, W

2016-01-01

Purpose: Recent advances in MRI-guided radiotherapy has inspired the development of MRI-compatible motion devices that simulate patient periodic motion in the scanner, particularly respiratory motion. Most commercial devices rely on non MR-safe ferromagnetic stepper motors which are not practical for regular QA testing. This work evaluates the motion performance of a new fully MRI compatible respiratory motion device at 3T. Methods: The QUASAR™ MRI-compatible respiratory motion phantom has been recently developed by Modus QA Inc., London, ON, Canada. The prototype is constructed from diamagnetic materials with linear motion generated using MRI-compatible piezoelectric motors that can be safely inserted in the scanner bore. The tumor was represented by a fillable sphere and is attached to the linear motion generator. The spherical tumor-representative and its surroundings were filled with different concentrations of MnCl2 to produce realistic relaxation times. The motion was generated along the longitudinal (H/F) axis of the bore using sinusoidal reference waveform (amplitude = 15 mm, frequency 0.25 Hz). Imaging was then performed on 3T Philips Achieva using a 32-channel cardiac coil. Fast 2D spoiled gradient-echo was used with a spatial resolution of 1.8 × 1.8 mm 2 and slice thickness of 4 mm. The motion waveform was then measured on the resultant image series by tracking the centroid of the sphere through the time series. This image-derived measured motion was compared to the software-generated reference waveform. Results: No visible distortions from the device were observed on the images. Excellent agreement between the measured and the reference waveforms were obtained. Negligible motion was observed in the lateral (R/L) direction. Conclusion: Our investigation demonstrates that this piezo-electric motor design is effective at simulating periodic motion and is a potential candidate for MRI-radiotherapy respiratory motion simulation. Future work should focus

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

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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.

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.

A viscoelastic model of the correlation between respiratory lung tumour motion and an external abdominal signal

International Nuclear Information System (INIS)

Cavan, A.E.; Wilson, P.L.; Meyer, J.; Berbeco, R.I.

2010-01-01

Full text: Accuracy of radiotherapy treatment of lung cancer is limited by respiratory induced tumour motion. Compensation for this motion is required to increase treatment efficacy. The lung tumour motion is related to motion of an external abdominal marker, but a reliable model of this correlation is essential. Three viscoelastic systems were developed, in order to determine the best model and analyse its effectiveness on clinical data. Three 1D viscoelastic systems (a spring and dash pot in parallel, series and a combination) were developed and compared using a simulated breathing pattern. The most effective model was applied to 60 clinical data sets (consisting of co-ordinates of tumour and abdominal motion) from multiple treatment fractions of ten patients. The model was optimised for each data set, and efficacy determined by calculating the root mean square (RMS) error between the mo elled position and the actual tumour motion. Upon application to clinical data the parallel configuration achieved an average RMS error of 0.95 mm (superior-inferior direction). The model had patient specific parameters, and displayed good consistency over extended treatment periods. The model ha dled amplitude, frequency and baseline variations of the input signal, and phase shifts between tumour and abdominal motions. This study has shown that a viscoelastic model can be used to cor relate internal lung tumour motion with an external abdominal signal. The ability to handle breathing pattern in'egularities is comparable or better than previous models. Extending the model to a full 3D, pr dictive system could allow clinical implementation for radiotherapy.

A continuous 4D motion model from multiple respiratory cycles for use in lung radiotherapy

International Nuclear Information System (INIS)

McClelland, Jamie R.; Blackall, Jane M.; Tarte, Segolene; Chandler, Adam C.; Hughes, Simon; Ahmad, Shahreen; Landau, David B.; Hawkes, David J.

2006-01-01

Respiratory motion causes errors when planning and delivering radiotherapy treatment to lung cancer patients. To reduce these errors, methods of acquiring and using four-dimensional computed tomography (4DCT) datasets have been developed. We have developed a novel method of constructing computational motion models from 4DCT. The motion models attempt to describe an average respiratory cycle, which reduces the effects of variation between different cycles. They require substantially less memory than a 4DCT dataset, are continuous in space and time, and facilitate automatic target propagation and combining of doses over the respiratory cycle. The motion models are constructed from CT data acquired in cine mode while the patient is free breathing (free breathing CT - FBCT). A ''slab'' of data is acquired at each couch position, with 3-4 contiguous slabs being acquired per patient. For each slab a sequence of 20 or 30 volumes was acquired over 20 seconds. A respiratory signal is simultaneously recorded in order to calculate the position in the respiratory cycle for each FBCT. Additionally, a high quality reference CT volume is acquired at breath hold. The reference volume is nonrigidly registered to each of the FBCT volumes. A motion model is then constructed for each slab by temporally fitting the nonrigid registration results. The value of each of the registration parameters is related to the position in the respiratory cycle by fitting an approximating B spline to the registration results. As an approximating function is used, and the data is acquired over several respiratory cycles, the function should model an average respiratory cycle. This can then be used to calculate the value of each degree of freedom at any desired position in the respiratory cycle. The resulting nonrigid transformation will deform the reference volume to predict the contents of the slab at the desired position in the respiratory cycle. The slab model predictions are then concatenated to

Real-time prediction of respiratory motion using a cascade structure of an extended Kalman filter and support vector regression.

Science.gov (United States)

Hong, S-M; Bukhari, W

2014-07-07

The motion of thoracic and abdominal tumours induced by respiratory motion often exceeds 20 mm, and can significantly compromise dose conformality. Motion-adaptive radiotherapy aims to deliver a conformal dose distribution to the tumour with minimal normal tissue exposure by compensating for the tumour motion. This adaptive radiotherapy, however, requires the prediction of the tumour movement that can occur over the system latency period. In general, motion prediction approaches can be classified into two groups: model-based and model-free. Model-based approaches utilize a motion model in predicting respiratory motion. These approaches are computationally efficient and responsive to irregular changes in respiratory motion. Model-free approaches do not assume an explicit model of motion dynamics, and predict future positions by learning from previous observations. Artificial neural networks (ANNs) and support vector regression (SVR) are examples of model-free approaches. In this article, we present a prediction algorithm that combines a model-based and a model-free approach in a cascade structure. The algorithm, which we call EKF-SVR, first employs a model-based algorithm (named LCM-EKF) to predict the respiratory motion, and then uses a model-free SVR algorithm to estimate and correct the error of the LCM-EKF prediction. Extensive numerical experiments based on a large database of 304 respiratory motion traces are performed. The experimental results demonstrate that the EKF-SVR algorithm successfully reduces the prediction error of the LCM-EKF, and outperforms the model-free ANN and SVR algorithms in terms of prediction accuracy across lookahead lengths of 192, 384, and 576 ms.

Real-time prediction of respiratory motion using a cascade structure of an extended Kalman filter and support vector regression

International Nuclear Information System (INIS)

Hong, S-M; Bukhari, W

2014-01-01

The motion of thoracic and abdominal tumours induced by respiratory motion often exceeds 20 mm, and can significantly compromise dose conformality. Motion-adaptive radiotherapy aims to deliver a conformal dose distribution to the tumour with minimal normal tissue exposure by compensating for the tumour motion. This adaptive radiotherapy, however, requires the prediction of the tumour movement that can occur over the system latency period. In general, motion prediction approaches can be classified into two groups: model-based and model-free. Model-based approaches utilize a motion model in predicting respiratory motion. These approaches are computationally efficient and responsive to irregular changes in respiratory motion. Model-free approaches do not assume an explicit model of motion dynamics, and predict future positions by learning from previous observations. Artificial neural networks (ANNs) and support vector regression (SVR) are examples of model-free approaches. In this article, we present a prediction algorithm that combines a model-based and a model-free approach in a cascade structure. The algorithm, which we call EKF–SVR, first employs a model-based algorithm (named LCM–EKF) to predict the respiratory motion, and then uses a model-free SVR algorithm to estimate and correct the error of the LCM–EKF prediction. Extensive numerical experiments based on a large database of 304 respiratory motion traces are performed. The experimental results demonstrate that the EKF–SVR algorithm successfully reduces the prediction error of the LCM–EKF, and outperforms the model-free ANN and SVR algorithms in terms of prediction accuracy across lookahead lengths of 192, 384, and 576 ms. (paper)

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)

Local respiratory motion correction for PET/CT imaging: Application to lung cancer

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Lamare, F., E-mail: frederic.lamare@chu-bordeaux.fr; Fernandez, P. [INCIA, UMR 5287, University of Bordeaux, Talence F-33400, France and Nuclear Medicine Department, University Hospital, Bordeaux 33000 (France); Fayad, H.; Visvikis, D. [INSERM, UMR1101, LaTIM, Université de Bretagne Occidentale, Brest 29609 (France)

2015-10-15

Purpose: Despite multiple methodologies already proposed to correct respiratory motion in the whole PET imaging field of view (FOV), such approaches have not found wide acceptance in clinical routine. An alternative can be the local respiratory motion correction (LRMC) of data corresponding to a given volume of interest (VOI: organ or tumor). Advantages of LRMC include the use of a simple motion model, faster execution times, and organ specific motion correction. The purpose of this study was to evaluate the performance of LMRC using various motion models for oncology (lung lesion) applications. Methods: Both simulated (NURBS based 4D cardiac-torso phantom) and clinical studies (six patients) were used in the evaluation of the proposed LRMC approach. PET data were acquired in list-mode and synchronized with respiration. The implemented approach consists first in defining a VOI on the reconstructed motion average image. Gated PET images of the VOI are subsequently reconstructed using only lines of response passing through the selected VOI and are used in combination with a center of gravity or an affine/elastic registration algorithm to derive the transformation maps corresponding to the respiration effects. Those are finally integrated in the reconstruction process to produce a motion free image over the lesion regions. Results: Although the center of gravity or affine algorithm achieved similar performance for individual lesion motion correction, the elastic model, applied either locally or to the whole FOV, led to an overall superior performance. The spatial tumor location was altered by 89% and 81% for the elastic model applied locally or to the whole FOV, respectively (compared to 44% and 39% for the center of gravity and affine models, respectively). This resulted in similar associated overall tumor volume changes of 84% and 80%, respectively (compared to 75% and 71% for the center of gravity and affine models, respectively). The application of the nonrigid

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)

Human torso phantom for imaging of heart with realistic modes of cardiac and respiratory motion

Science.gov (United States)

Boutchko, Rostyslav; Balakrishnan, Karthikayan; Gullberg, Grant T; O& #x27; Neil, James P

2013-09-17

A human torso phantom and its construction, wherein the phantom mimics respiratory and cardiac cycles in a human allowing acquisition of medical imaging data under conditions simulating patient cardiac and respiratory motion.

Experimental verification of a two-dimensional respiratory motion compensation system with ultrasound tracking technique in radiation therapy.

Science.gov (United States)

Ting, Lai-Lei; Chuang, Ho-Chiao; Liao, Ai-Ho; Kuo, Chia-Chun; Yu, Hsiao-Wei; Zhou, Yi-Liang; Tien, Der-Chi; Jeng, Shiu-Chen; Chiou, Jeng-Fong

2018-05-01

This study proposed respiratory motion compensation system (RMCS) combined with an ultrasound image tracking algorithm (UITA) to compensate for respiration-induced tumor motion during radiotherapy, and to address the problem of inaccurate radiation dose delivery caused by respiratory movement. This study used an ultrasound imaging system to monitor respiratory movements combined with the proposed UITA and RMCS for tracking and compensation of the respiratory motion. Respiratory motion compensation was performed using prerecorded human respiratory motion signals and also sinusoidal signals. A linear accelerator was used to deliver radiation doses to GAFchromic EBT3 dosimetry film, and the conformity index (CI), root-mean-square error, compensation rate (CR), and planning target volume (PTV) were used to evaluate the tracking and compensation performance of the proposed system. Human respiratory pattern signals were captured using the UITA and compensated by the RMCS, which yielded CR values of 34-78%. In addition, the maximum coronal area of the PTV ranged from 85.53 mm 2 to 351.11 mm 2 (uncompensated), which reduced to from 17.72 mm 2 to 66.17 mm 2 after compensation, with an area reduction ratio of up to 90%. In real-time monitoring of the respiration compensation state, the CI values for 85% and 90% isodose areas increased to 0.7 and 0.68, respectively. The proposed UITA and RMCS can reduce the movement of the tracked target relative to the LINAC in radiation therapy, thereby reducing the required size of the PTV margin and increasing the effect of the radiation dose received by the treatment target. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Online prediction of respiratory motion: multidimensional processing with low-dimensional feature learning

International Nuclear Information System (INIS)

Ruan, Dan; Keall, Paul

2010-01-01

Accurate real-time prediction of respiratory motion is desirable for effective motion management in radiotherapy for lung tumor targets. Recently, nonparametric methods have been developed and their efficacy in predicting one-dimensional respiratory-type motion has been demonstrated. To exploit the correlation among various coordinates of the moving target, it is natural to extend the 1D method to multidimensional processing. However, the amount of learning data required for such extension grows exponentially with the dimensionality of the problem, a phenomenon known as the 'curse of dimensionality'. In this study, we investigate a multidimensional prediction scheme based on kernel density estimation (KDE) in an augmented covariate-response space. To alleviate the 'curse of dimensionality', we explore the intrinsic lower dimensional manifold structure and utilize principal component analysis (PCA) to construct a proper low-dimensional feature space, where kernel density estimation is feasible with the limited training data. Interestingly, the construction of this lower dimensional representation reveals a useful decomposition of the variations in respiratory motion into the contribution from semiperiodic dynamics and that from the random noise, as it is only sensible to perform prediction with respect to the former. The dimension reduction idea proposed in this work is closely related to feature extraction used in machine learning, particularly support vector machines. This work points out a pathway in processing high-dimensional data with limited training instances, and this principle applies well beyond the problem of target-coordinate-based respiratory-based prediction. A natural extension is prediction based on image intensity directly, which we will investigate in the continuation of this work. We used 159 lung target motion traces obtained with a Synchrony respiratory tracking system. Prediction performance of the low-dimensional feature learning

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

Concurrent Respiratory Motion Correction of Abdominal PET and DCE-MRI using a Compressed Sensing Approach.

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Fuin, Niccolo; Catalano, Onofrio Antonio; Scipioni, Michele; Canjels, Lisanne P W; Izquierdo, David; Pedemonte, Stefano; Catana, Ciprian

2018-01-25

Purpose: We present an approach for concurrent reconstruction of respiratory motion compensated abdominal DCE-MRI and PET data in an integrated PET/MR scanner. The MR and PET reconstructions share the same motion vector fields (MVFs) derived from radial MR data; the approach is robust to changes in respiratory pattern and do not increase the total acquisition time. Methods: PET and DCE-MRI data of 12 oncological patients were simultaneously acquired for 6 minutes on an integrated PET/MR system after administration of 18 F-FDG and gadoterate meglumine. Golden-angle radial MR data were continuously acquired simultaneously with PET data and sorted into multiple motion phases based on a respiratory signal derived directly from the radial MR data. The resulting multidimensional dataset was reconstructed using a compressed sensing approach that exploits sparsity among respiratory phases. MVFs obtained using the full 6-minute (MC_6-min) and only the last 1 minute (MC_1-min) of data were incorporated into the PET reconstruction to obtain motion-corrected PET images and in an MR iterative reconstruction algorithm to produce a series of motion-corrected DCE-MRI images (moco_GRASP). The motion-correction methods (MC_6-min and MC_1-min) were evaluated by qualitative analysis of the MR images and quantitative analysis of maximum and mean standardized uptake values (SUV max , SUVmean), contrast, signal-to-noise ratio (SNR) and lesion volume in the PET images. Results: Motion corrected MC_6-min PET images demonstrated 30%, 23%, 34% and 18% increases in average SUV max , SUVmean, contrast and SNR, and an average 40% reduction in lesion volume with respect to the non-motion-corrected PET images. The changes in these figures of merit were smaller but still substantial for the MC_1-min protocol: 19%, 10%, 15% and 9% increases in average SUV max , SUVmean, contrast and SNR; and a 28% reduction in lesion volume. Moco_GRASP images were deemed of acceptable or better diagnostic image

Comparison of visual biofeedback system with a guiding waveform and abdomen-chest motion self-control system for respiratory motion management

International Nuclear Information System (INIS)

Nakajima, Yujiro; Kadoya, Noriyuki; Kanai, Takayuki; Ito, Kengo; Sato, Kiyokazu; Dobashi, Suguru; Yamamoto, Takaya; Ishikawa, Yojiro; Matsushita, Haruo; Takeda, Ken; Jingu, Keiichi

2016-01-01

Irregular breathing can influence the outcome of 4D computed tomography imaging and cause artifacts. Visual biofeedback systems associated with a patient-specific guiding waveform are known to reduce respiratory irregularities. In Japan, abdomen and chest motion self-control devices (Abches) (representing simpler visual coaching techniques without a guiding waveform) are used instead; however, no studies have compared these two systems to date. Here, we evaluate the effectiveness of respiratory coaching in reducing respiratory irregularities by comparing two respiratory management systems. We collected data from 11 healthy volunteers. Bar and wave models were used as visual biofeedback systems. Abches consisted of a respiratory indicator indicating the end of each expiration and inspiration motion. Respiratory variations were quantified as root mean squared error (RMSE) of displacement and period of breathing cycles. All coaching techniques improved respiratory variation, compared with free-breathing. Displacement RMSEs were 1.43 ± 0.84, 1.22 ± 1.13, 1.21 ± 0.86 and 0.98 ± 0.47 mm for free-breathing, Abches, bar model and wave model, respectively. Period RMSEs were 0.48 ± 0.42, 0.33 ± 0.31, 0.23 ± 0.18 and 0.17 ± 0.05 s for free-breathing, Abches, bar model and wave model, respectively. The average reduction in displacement and period RMSE compared with the wave model were 27% and 47%, respectively. For variation in both displacement and period, wave model was superior to the other techniques. Our results showed that visual biofeedback combined with a wave model could potentially provide clinical benefits in respiratory management, although all techniques were able to reduce respiratory irregularities

Development of Abdominal Compression Belt and Evaluation of the Efficiency for the Reduction of Respiratory Motion in SBRT

International Nuclear Information System (INIS)

Hwang, Seon Bung; Kim, Il Hwan; Kim, Woong; Im, Hyeong Seo; Gang, Jin Mook; Jeong, Seong Min; Kim, Gi Hwan; Lee, Ah Ram; Cho, Yura

2011-01-01

It's essential to minimize the tumor motion and identify the exact location of the lesions to achieve the improvement in radiation therapy efficiency during SBRT. In this study, we made the established compression belt to reduce respiratory motion and evaluated the usefulness of clinical application in SBRT. We analyzed the merits and demerits of the established compression belt to reduce the respiratory motion and improved the reproducibility and precision in use. To evaluate the usefulness of improved compression belt for respiratory motion reduction in SBRT, firstly, we reviewed the spiral CT images acquired in inspiration and expiration states of 8 lung cancer cases, respectively, and analyzed the three dimensional tumor motion related to respiration. To evaluate isodose distribution, secondly, we also made the special phantom using EBT2 film (Gafchronic, ISP, USA) and we prepared the robot (Cartesian Robot-2 Axis, FARARCM4H, Samsung Mechatronics, Korea) to reproduce three dimensional tumor motion. And analysis was made for isodose curves and two dimensional isodose profiles with reproducibility of respiratory motion on the basis of CT images. A respiratory motion reduction compression belt (Velcro type) that has convenient use and good reproducibility was developed. The moving differences of three dimensional tumor motion of lung cancer cases analyzed by CT images were mean 3.2 mm, 4.3 mm and 13 mm each in LR, AP and CC directions. The result of characteristic change in dose distribution using the phantom and rectangular coordinates robot showed that the distortion of isodose has great differences, mean length was 4.2 mm; the differences were 8.0% and 16.8% each for cranio-caudal and 8.1% and 10.9% each for left-right directions in underdose below the prescribed dose. In this study, we could develop the convenient and efficient compression belt that can make the organs' motion minimize. With this compression belt, we confirmed that underdose due to respiration

Development of Abdominal Compression Belt and Evaluation of the Efficiency for the Reduction of Respiratory Motion in SBRT

Energy Technology Data Exchange (ETDEWEB)

Hwang, Seon Bung; Kim, Il Hwan; Kim, Woong; Im, Hyeong Seo; Gang, Jin Mook; Jeong, Seong Min; Kim, Gi Hwan; Lee, Ah Ram [Dept. of Radiation and Oncology, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Cho, Yura [Dept. of Cyberknife, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

2011-03-15

It's essential to minimize the tumor motion and identify the exact location of the lesions to achieve the improvement in radiation therapy efficiency during SBRT. In this study, we made the established compression belt to reduce respiratory motion and evaluated the usefulness of clinical application in SBRT. We analyzed the merits and demerits of the established compression belt to reduce the respiratory motion and improved the reproducibility and precision in use. To evaluate the usefulness of improved compression belt for respiratory motion reduction in SBRT, firstly, we reviewed the spiral CT images acquired in inspiration and expiration states of 8 lung cancer cases, respectively, and analyzed the three dimensional tumor motion related to respiration. To evaluate isodose distribution, secondly, we also made the special phantom using EBT2 film (Gafchronic, ISP, USA) and we prepared the robot (Cartesian Robot-2 Axis, FARARCM4H, Samsung Mechatronics, Korea) to reproduce three dimensional tumor motion. And analysis was made for isodose curves and two dimensional isodose profiles with reproducibility of respiratory motion on the basis of CT images. A respiratory motion reduction compression belt (Velcro type) that has convenient use and good reproducibility was developed. The moving differences of three dimensional tumor motion of lung cancer cases analyzed by CT images were mean 3.2 mm, 4.3 mm and 13 mm each in LR, AP and CC directions. The result of characteristic change in dose distribution using the phantom and rectangular coordinates robot showed that the distortion of isodose has great differences, mean length was 4.2 mm; the differences were 8.0% and 16.8% each for cranio-caudal and 8.1% and 10.9% each for left-right directions in underdose below the prescribed dose. In this study, we could develop the convenient and efficient compression belt that can make the organs' motion minimize. With this compression belt, we confirmed that underdose due to

Four dimensional digital tomosynthesis using on-board imager for the verification of respiratory motion.

Directory of Open Access Journals (Sweden)

Justin C Park

Full Text Available PURPOSE: To evaluate respiratory motion of a patient by generating four-dimensional digital tomosynthesis (4D DTS, extracting respiratory signal from patients' on-board projection data, and ensuring the feasibility of 4D DTS as a localization tool for the targets which have respiratory movement. METHODS AND MATERIALS: Four patients with lung and liver cancer were included to verify the feasibility of 4D-DTS with an on-board imager. CBCT acquisition (650-670 projections was used to reconstruct 4D DTS images and the breath signal of the patients was generated by extracting the motion of diaphragm during data acquisition. Based on the extracted signal, the projection data was divided into four phases: peak-exhale phase, mid-inhale phase, peak-inhale phase, and mid-exhale phase. The binned projection data was then used to generate 4D DTS, where the total scan angle was assigned as ±22.5° from rotation center, centered on 0° and 180° for coronal "half-fan" 4D DTS, and 90° and 270° for sagittal "half-fan" 4D DTS. The result was then compared with 4D CBCT which we have also generated with the same phase distribution. RESULTS: The motion of the diaphragm was evident from the 4D DTS results for peak-exhale, mid-inhale, peak-inhale and mid-exhale phase assignment which was absent in 3D DTS. Compared to the result of 4D CBCT, the view aliasing effect due to arbitrary angle reconstruction was less severe. In addition, the severity of metal artifacts, the image distortion due to presence of metal, was less than that of the 4D CBCT results. CONCLUSION: We have implemented on-board 4D DTS on patients data to visualize the movement of anatomy due to respiratory motion. The results indicate that 4D-DTS could be a promising alternative to 4D CBCT for acquiring the respiratory motion of internal organs just prior to radiotherapy treatment.

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

SU-E-T-452: Impact of Respiratory Motion On Robustly-Optimized Intensity-Modulated Proton Therapy to Treat Lung Cancers

International Nuclear Information System (INIS)

Liu, W; Schild, S; Bues, M; Liao, Z; Sahoo, N; Park, P; Li, H; Li, Y; Li, X; Shen, J; Anand, A; Dong, L; Zhu, X; Mohan, R

2014-01-01

Purpose: We compared conventionally optimized intensity-modulated proton therapy (IMPT) treatment plans against the worst-case robustly optimized treatment plans for lung cancer. The comparison of the two IMPT optimization strategies focused on the resulting plans' ability to retain dose objectives under the influence of patient set-up, inherent proton range uncertainty, and dose perturbation caused by respiratory motion. Methods: For each of the 9 lung cancer cases two treatment plans were created accounting for treatment uncertainties in two different ways: the first used the conventional Method: delivery of prescribed dose to the planning target volume (PTV) that is geometrically expanded from the internal target volume (ITV). The second employed the worst-case robust optimization scheme that addressed set-up and range uncertainties through beamlet optimization. The plan optimality and plan robustness were calculated and compared. Furthermore, the effects on dose distributions of the changes in patient anatomy due to respiratory motion was investigated for both strategies by comparing the corresponding plan evaluation metrics at the end-inspiration and end-expiration phase and absolute differences between these phases. The mean plan evaluation metrics of the two groups were compared using two-sided paired t-tests. Results: Without respiratory motion considered, we affirmed that worst-case robust optimization is superior to PTV-based conventional optimization in terms of plan robustness and optimality. With respiratory motion considered, robust optimization still leads to more robust dose distributions to respiratory motion for targets and comparable or even better plan optimality [D95% ITV: 96.6% versus 96.1% (p=0.26), D5% - D95% ITV: 10.0% versus 12.3% (p=0.082), D1% spinal cord: 31.8% versus 36.5% (p =0.035)]. Conclusion: Worst-case robust optimization led to superior solutions for lung IMPT. Despite of the fact that robust optimization did not explicitly

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)

Effects of Respiratory Motion on Passively Scattered Proton Therapy Versus Intensity Modulated Photon Therapy for Stage III Lung Cancer: Are Proton Plans More Sensitive to Breathing Motion?

International Nuclear Information System (INIS)

Matney, Jason; Park, Peter C.; Bluett, Jaques; Chen, Yi Pei; Liu, Wei; Court, Laurence E.; Liao, Zhongxing; Li, Heng; Mohan, Radhe

2013-01-01

Purpose: To quantify and compare the effects of respiratory motion on paired passively scattered proton therapy (PSPT) and intensity modulated photon therapy (IMRT) plans; and to establish the relationship between the magnitude of tumor motion and the respiratory-induced dose difference for both modalities. Methods and Materials: In a randomized clinical trial comparing PSPT and IMRT, radiation therapy plans have been designed according to common planning protocols. Four-dimensional (4D) dose was computed for PSPT and IMRT plans for a patient cohort with respiratory motion ranging from 3 to 17 mm. Image registration and dose accumulation were performed using grayscale-based deformable image registration algorithms. The dose–volume histogram (DVH) differences (4D-3D [3D = 3-dimensional]) were compared for PSPT and IMRT. Changes in 4D-3D dose were correlated to the magnitude of tumor respiratory motion. Results: The average 4D-3D dose to 95% of the internal target volume was close to zero, with 19 of 20 patients within 1% of prescribed dose for both modalities. The mean 4D-3D between the 2 modalities was not statistically significant (P<.05) for all dose–volume histogram indices (mean ± SD) except the lung V5 (PSPT: +1.1% ± 0.9%; IMRT: +0.4% ± 1.2%) and maximum cord dose (PSPT: +1.5 ± 2.9 Gy; IMRT: 0.0 ± 0.2 Gy). Changes in 4D-3D dose were correlated to tumor motion for only 2 indices: dose to 95% planning target volume, and heterogeneity index. Conclusions: With our current margin formalisms, target coverage was maintained in the presence of respiratory motion up to 17 mm for both PSPT and IMRT. Only 2 of 11 4D-3D indices (lung V5 and spinal cord maximum) were statistically distinguishable between PSPT and IMRT, contrary to the notion that proton therapy will be more susceptible to respiratory motion. Because of the lack of strong correlations with 4D-3D dose differences in PSPT and IMRT, the extent of tumor motion was not an adequate predictor of potential

Effects of Respiratory Motion on Passively Scattered Proton Therapy Versus Intensity Modulated Photon Therapy for Stage III Lung Cancer: Are Proton Plans More Sensitive to Breathing Motion?

Energy Technology Data Exchange (ETDEWEB)

Matney, Jason; Park, Peter C. [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); The University of Texas Graduate School of Biomedical Sciences, Houston, Texas (United States); Bluett, Jaques [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Chen, Yi Pei [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); The University of Texas Graduate School of Biomedical Sciences, Houston, Texas (United States); Liu, Wei; Court, Laurence E. [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Liao, Zhongxing [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Li, Heng [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Mohan, Radhe, E-mail: rmohan@mdanderson.org [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2013-11-01

Purpose: To quantify and compare the effects of respiratory motion on paired passively scattered proton therapy (PSPT) and intensity modulated photon therapy (IMRT) plans; and to establish the relationship between the magnitude of tumor motion and the respiratory-induced dose difference for both modalities. Methods and Materials: In a randomized clinical trial comparing PSPT and IMRT, radiation therapy plans have been designed according to common planning protocols. Four-dimensional (4D) dose was computed for PSPT and IMRT plans for a patient cohort with respiratory motion ranging from 3 to 17 mm. Image registration and dose accumulation were performed using grayscale-based deformable image registration algorithms. The dose–volume histogram (DVH) differences (4D-3D [3D = 3-dimensional]) were compared for PSPT and IMRT. Changes in 4D-3D dose were correlated to the magnitude of tumor respiratory motion. Results: The average 4D-3D dose to 95% of the internal target volume was close to zero, with 19 of 20 patients within 1% of prescribed dose for both modalities. The mean 4D-3D between the 2 modalities was not statistically significant (P<.05) for all dose–volume histogram indices (mean ± SD) except the lung V5 (PSPT: +1.1% ± 0.9%; IMRT: +0.4% ± 1.2%) and maximum cord dose (PSPT: +1.5 ± 2.9 Gy; IMRT: 0.0 ± 0.2 Gy). Changes in 4D-3D dose were correlated to tumor motion for only 2 indices: dose to 95% planning target volume, and heterogeneity index. Conclusions: With our current margin formalisms, target coverage was maintained in the presence of respiratory motion up to 17 mm for both PSPT and IMRT. Only 2 of 11 4D-3D indices (lung V5 and spinal cord maximum) were statistically distinguishable between PSPT and IMRT, contrary to the notion that proton therapy will be more susceptible to respiratory motion. Because of the lack of strong correlations with 4D-3D dose differences in PSPT and IMRT, the extent of tumor motion was not an adequate predictor of potential

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.

Comparative analysis of respiratory motion tracking using Microsoft Kinect v2 sensor.

Science.gov (United States)

Silverstein, Evan; Snyder, Michael

2018-05-01

To present and evaluate a straightforward implementation of a marker-less, respiratory motion-tracking process utilizing Kinect v2 camera as a gating tool during 4DCT or during radiotherapy treatments. Utilizing the depth sensor on the Kinect as well as author written C# code, respiratory motion of a subject was tracked by recording depth values obtained at user selected points on the subject, with each point representing one pixel on the depth image. As a patient breathes, specific anatomical points on the chest/abdomen will move slightly within the depth image across pixels. By tracking how depth values change for a specific pixel, instead of how the anatomical point moves throughout the image, a respiratory trace can be obtained based on changing depth values of the selected pixel. Tracking these values was implemented via marker-less setup. Varian's RPM system and the Anzai belt system were used in tandem with the Kinect to compare respiratory traces obtained by each using two different subjects. Analysis of the depth information from the Kinect for purposes of phase- and amplitude-based binning correlated well with the RPM and Anzai systems. Interquartile Range (IQR) values were obtained comparing times correlated with specific amplitude and phase percentages against each product. The IQR time spans indicated the Kinect would measure specific percentage values within 0.077 s for Subject 1 and 0.164 s for Subject 2 when compared to values obtained with RPM or Anzai. For 4DCT scans, these times correlate to less than 1 mm of couch movement and would create an offset of 1/2 an acquired slice. By tracking depth values of user selected pixels within the depth image, rather than tracking specific anatomical locations, respiratory motion can be tracked and visualized utilizing the Kinect with results comparable to that of the Varian RPM and Anzai belt. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of

Respiratory motion prediction by using the adaptive neuro fuzzy inference system (ANFIS)

International Nuclear Information System (INIS)

Kakar, Manish; Nystroem, Haakan; Aarup, Lasse Rye; Noettrup, Trine Jakobi; Olsen, Dag Rune

2005-01-01

The quality of radiation therapy delivered for treating cancer patients is related to set-up errors and organ motion. Due to the margins needed to ensure adequate target coverage, many breast cancer patients have been shown to develop late side effects such as pneumonitis and cardiac damage. Breathing-adapted radiation therapy offers the potential for precise radiation dose delivery to a moving target and thereby reduces the side effects substantially. However, the basic requirement for breathing-adapted radiation therapy is to track and predict the target as precisely as possible. Recent studies have addressed the problem of organ motion prediction by using different methods including artificial neural network and model based approaches. In this study, we propose to use a hybrid intelligent system called ANFIS (the adaptive neuro fuzzy inference system) for predicting respiratory motion in breast cancer patients. In ANFIS, we combine both the learning capabilities of a neural network and reasoning capabilities of fuzzy logic in order to give enhanced prediction capabilities, as compared to using a single methodology alone. After training ANFIS and checking for prediction accuracy on 11 breast cancer patients, it was found that the RMSE (root-mean-square error) can be reduced to sub-millimetre accuracy over a period of 20 s provided the patient is assisted with coaching. The average RMSE for the un-coached patients was 35% of the respiratory amplitude and for the coached patients 6% of the respiratory amplitude

Respiratory motion prediction by using the adaptive neuro fuzzy inference system (ANFIS)

Energy Technology Data Exchange (ETDEWEB)

Kakar, Manish [Department of Radiation Biology, Norwegian Radium Hospital, Montebello, 0310 Oslo (Norway); Nystroem, Haakan [Department of Radiation Oncology, The Finsen Centre, Rigshospitalet, Copenhagen (Denmark); Aarup, Lasse Rye [Department of Radiation Oncology, The Finsen Centre, Rigshospitalet, Copenhagen (Denmark); Noettrup, Trine Jakobi [Department of Radiation Oncology, The Finsen Centre, Rigshospitalet, Copenhagen (Denmark); Olsen, Dag Rune [Department of Radiation Biology, Norwegian Radium Hospital, Montebello, 0310 Oslo (Norway); Department of Medical Physics and Technology, Norwegian Radium Hospital, Oslo (Norway); Department of Physics, University of Oslo (Norway)

2005-10-07

The quality of radiation therapy delivered for treating cancer patients is related to set-up errors and organ motion. Due to the margins needed to ensure adequate target coverage, many breast cancer patients have been shown to develop late side effects such as pneumonitis and cardiac damage. Breathing-adapted radiation therapy offers the potential for precise radiation dose delivery to a moving target and thereby reduces the side effects substantially. However, the basic requirement for breathing-adapted radiation therapy is to track and predict the target as precisely as possible. Recent studies have addressed the problem of organ motion prediction by using different methods including artificial neural network and model based approaches. In this study, we propose to use a hybrid intelligent system called ANFIS (the adaptive neuro fuzzy inference system) for predicting respiratory motion in breast cancer patients. In ANFIS, we combine both the learning capabilities of a neural network and reasoning capabilities of fuzzy logic in order to give enhanced prediction capabilities, as compared to using a single methodology alone. After training ANFIS and checking for prediction accuracy on 11 breast cancer patients, it was found that the RMSE (root-mean-square error) can be reduced to sub-millimetre accuracy over a period of 20 s provided the patient is assisted with coaching. The average RMSE for the un-coached patients was 35% of the respiratory amplitude and for the coached patients 6% of the respiratory amplitude.

A 4D global respiratory motion model of the thorax based on CT images: A proof of concept.

Science.gov (United States)

Fayad, Hadi; Gilles, Marlene; Pan, Tinsu; Visvikis, Dimitris

2018-05-17

Respiratory motion reduces the sensitivity and specificity of medical images especially in the thoracic and abdominal areas. It may affect applications such as cancer diagnostic imaging and/or radiation therapy (RT). Solutions to this issue include modeling of the respiratory motion in order to optimize both diagnostic and therapeutic protocols. Personalized motion modeling required patient-specific four-dimensional (4D) imaging which in the case of 4D computed tomography (4D CT) acquisition is associated with an increased dose. The goal of this work was to develop a global respiratory motion model capable of relating external patient surface motion to internal structure motion without the need for a patient-specific 4D CT acquisition. The proposed global model is based on principal component analysis and can be adjusted to a given patient anatomy using only one or two static CT images in conjunction with a respiratory synchronized patient external surface motion. It is based on the relation between the internal motion described using deformation fields obtained by registering 4D CT images and patient surface maps obtained either from optical imaging devices or extracted from CT image-based patient skin segmentation. 4D CT images of six patients were used to generate the global motion model which was validated by adapting it on four different patients having skin segmented surfaces and two other patients having time of flight camera acquired surfaces. The reproducibility of the proposed model was also assessed on two patients with two 4D CT series acquired within 2 weeks of each other. Profile comparison shows the efficacy of the global respiratory motion model and an improvement while using two CT images in order to adapt the model. This was confirmed by the correlation coefficient with a mean correlation of 0.9 and 0.95 while using one or two CT images respectively and when comparing acquired to model generated 4D CT images. For the four patients with segmented

MRI-based measurements of respiratory motion variability and assessment of imaging strategies for radiotherapy planning

International Nuclear Information System (INIS)

Blackall, J M; Ahmad, S; Miquel, M E; McClelland, J R; Landau, D B; Hawkes, D J

2006-01-01

Respiratory organ motion has a significant impact on the planning and delivery of radiotherapy (RT) treatment for lung cancer. Currently widespread techniques, such as 4D-computed tomography (4DCT), cannot be used to measure variability of this motion from one cycle to the next. In this paper, we describe the use of fast magnetic resonance imaging (MRI) techniques to investigate the intra- and inter-cycle reproducibility of respiratory motion and also to estimate the level of errors that may be introduced into treatment delivery by using various breath-hold imaging strategies during lung RT planning. A reference model of respiratory motion is formed to enable comparison of different breathing cycles at any arbitrary position in the respiratory cycle. This is constructed by using free-breathing images from the inhale phase of a single breathing cycle, then co-registering the images, and thereby tracking landmarks. This reference model is then compared to alternative models constructed from images acquired during the exhale phase of the same cycle and the inhale phase of a subsequent cycle, to assess intra- and inter-cycle variability ('hysteresis' and 'reproducibility') of organ motion. The reference model is also compared to a series of models formed from breath-hold data at exhale and inhale. Evaluation of these models is carried out on data from ten healthy volunteers and five lung cancer patients. Free-breathing models show good levels of intra- and inter-cycle reproducibility across the tidal breathing range. Mean intra-cycle errors in the position of organ surface landmarks of 1.5(1.4)-3.5(3.3) mm for volunteers and 2.8(1.8)-5.2(5.2) mm for patients. Equivalent measures of inter-cycle variability across this range are 1.7(1.0)-3.9(3.3) mm for volunteers and 2.8(1.8)-3.3(2.2) mm for patients. As expected, models based on breath-hold sequences do not represent normal tidal motion as well as those based on free-breathing data, with mean errors of 4

On transcending the impasse of respiratory motion correction applications in routine clinical imaging - a consideration of a fully automated data driven motion control framework

International Nuclear Information System (INIS)

Kesner, Adam L; Schleyer, Paul J; Büther, Florian; Walter, Martin A; Schäfers, Klaus P; Koo, Phillip J

2014-01-01

Positron emission tomography (PET) is increasingly used for the detection, characterization, and follow-up of tumors located in the thorax. However, patient respiratory motion presents a unique limitation that hinders the application of high-resolution PET technology for this type of imaging. Efforts to transcend this limitation have been underway for more than a decade, yet PET remains for practical considerations a modality vulnerable to motion-induced image degradation. Respiratory motion control is not employed in routine clinical operations. In this article, we take an opportunity to highlight some of the recent advancements in data-driven motion control strategies and how they may form an underpinning for what we are presenting as a fully automated data-driven motion control framework. This framework represents an alternative direction for future endeavors in motion control and can conceptually connect individual focused studies with a strategy for addressing big picture challenges and goals. The online version of this article (doi:10.1186/2197-7364-1-8) contains supplementary material, which is available to authorized users.

Usefulness of abdominal belt for restricting respiratory cardiac motion and improving image quality in myocardial perfusion PET.

Science.gov (United States)

Ichikawa, Yasutaka; Tomita, Yoya; Ishida, Masaki; Kobayashi, Shigeki; Takeda, Kan; Sakuma, Hajime

2018-04-01

The current study evaluated the usefulness of a belt technique for restricting respiratory motion of the heart and for improving image quality of 13 N-ammonia myocardial PET/CT, and it assessed the tolerability of the belt technique in the clinical setting. Myocardial 13 N-ammonia PET/CT scanning was performed in 8 volunteers on Discovery PET/CT 690 with an optical respiratory motion tracking system. Emission scans were performed with and without an abdominal belt. The amplitude of left ventricular (LV) respiratory motion was measured on respiratory-gated PET images. The degree of erroneous decreases in regional myocardial uptake was visually assessed on ungated PET images using a 5-point scale (0 = normal, 1/2/3 = mild/moderate/severe decrease, 4 = defect). The tolerability of the belt technique was evaluated in 53 patients. All subjects tolerated the belt procedure. The amplitude of the LV respiratory motion decreased significantly with the belt (8.1 ± 7.1 vs 12.1 ± 6.1 mm, P = .0078). The belt significantly improved the image quality scores in the anterior (0.29 ± 0.81 vs 0.71 ± 1.04, P = .015) and inferior (0.33 ± 0.92 vs 1.04 ± 1.04, P PET/CT, and it is well tolerated by patients.

Three-dimensional intrafractional internal target motions in accelerated partial breast irradiation using three-dimensional conformal external beam radiotherapy.

Science.gov (United States)

Hirata, Kimiko; Yoshimura, Michio; Mukumoto, Nobutaka; Nakamura, Mitsuhiro; Inoue, Minoru; Sasaki, Makoto; Fujimoto, Takahiro; Yano, Shinsuke; Nakata, Manabu; Mizowaki, Takashi; Hiraoka, Masahiro

2017-07-01

We evaluated three-dimensional intrafractional target motion, divided into respiratory-induced motion and baseline drift, in accelerated partial breast irradiation (APBI). Paired fluoroscopic images were acquired simultaneously using orthogonal kV X-ray imaging systems at pre- and post-treatment for 23 patients who underwent APBI with external beam radiotherapy. The internal target motion was calculated from the surgical clips placed around the tumour cavity. The peak-to-peak respiratory-induced motions ranged from 0.6 to 1.5mm in all directions. A systematic baseline drift of 1.5mm towards the posterior direction and a random baseline drift of 0.3mm in the lateral-medial and cranial-caudal directions were observed. The baseline for an outer tumour cavity drifted towards the lateral and posterior directions, and that for an upper tumour cavity drifted towards the cranial direction. Moderate correlations were observed between the posterior baseline drift and the patients' physical characteristics. The posterior margin for intrafractional uncertainties was larger than 5mm in patients with greater fat thickness due to the baseline drift. The magnitude of the intrafractional motion was not uniform according to the direction, patients' physical characteristics, or tumour cavity location due to the baseline drift. Therefore, the intrafractional systematic movement should be properly managed. Copyright © 2017 Elsevier B.V. All rights reserved.

A dual-Kinect approach to determine torso surface motion for respiratory motion correction in PET

International Nuclear Information System (INIS)

Heß, Mirco; Büther, Florian; Dawood, Mohammad; Schäfers, Klaus P.; Gigengack, Fabian

2015-01-01

Purpose: Respiratory gating is commonly used to reduce blurring effects and attenuation correction artifacts in positron emission tomography (PET). Established clinically available methods that employ body-attached hardware for acquiring respiration signals rely on the assumption that external surface motion and internal organ motion are well correlated. In this paper, the authors present a markerless method comprising two Microsoft Kinects for determining the motion on the whole torso surface and aim to demonstrate its validity and usefulness—including the potential to study the external/internal correlation and to provide useful information for more advanced correction approaches. Methods: The data of two Kinects are used to calculate 3D representations of a patient’s torso surface with high spatial coverage. Motion signals can be obtained for any position by tracking the mean distance to a virtual camera with a view perpendicular to the surrounding surface. The authors have conducted validation experiments including volunteers and a moving high-precision platform to verify the method’s suitability for providing meaningful data. In addition, the authors employed it during clinical 18 F-FDG-PET scans and exemplarily analyzed the acquired data of ten cancer patients. External signals of abdominal and thoracic regions as well as data-driven signals were used for gating and compared with respect to detected displacement of present lesions. Additionally, the authors quantified signal similarities and time shifts by analyzing cross-correlation sequences. Results: The authors’ results suggest a Kinect depth resolution of approximately 1 mm at 75 cm distance. Accordingly, valid signals could be obtained for surface movements with small amplitudes in the range of only few millimeters. In this small sample of ten patients, the abdominal signals were better suited for gating the PET data than the thoracic signals and the correlation of data-driven signals was found

A dual-Kinect approach to determine torso surface motion for respiratory motion correction in PET

Energy Technology Data Exchange (ETDEWEB)

Heß, Mirco, E-mail: mirco.hess@uni-muenster.de; Büther, Florian; Dawood, Mohammad; Schäfers, Klaus P. [European Institute for Molecular Imaging, University of Münster, Münster 48149 (Germany); Gigengack, Fabian [European Institute for Molecular Imaging, University of Münster, Münster 48149, Germany and Department of Mathematics and Computer Science, University of Münster, Münster 48149 (Germany)

2015-05-15

Purpose: Respiratory gating is commonly used to reduce blurring effects and attenuation correction artifacts in positron emission tomography (PET). Established clinically available methods that employ body-attached hardware for acquiring respiration signals rely on the assumption that external surface motion and internal organ motion are well correlated. In this paper, the authors present a markerless method comprising two Microsoft Kinects for determining the motion on the whole torso surface and aim to demonstrate its validity and usefulness—including the potential to study the external/internal correlation and to provide useful information for more advanced correction approaches. Methods: The data of two Kinects are used to calculate 3D representations of a patient’s torso surface with high spatial coverage. Motion signals can be obtained for any position by tracking the mean distance to a virtual camera with a view perpendicular to the surrounding surface. The authors have conducted validation experiments including volunteers and a moving high-precision platform to verify the method’s suitability for providing meaningful data. In addition, the authors employed it during clinical {sup 18}F-FDG-PET scans and exemplarily analyzed the acquired data of ten cancer patients. External signals of abdominal and thoracic regions as well as data-driven signals were used for gating and compared with respect to detected displacement of present lesions. Additionally, the authors quantified signal similarities and time shifts by analyzing cross-correlation sequences. Results: The authors’ results suggest a Kinect depth resolution of approximately 1 mm at 75 cm distance. Accordingly, valid signals could be obtained for surface movements with small amplitudes in the range of only few millimeters. In this small sample of ten patients, the abdominal signals were better suited for gating the PET data than the thoracic signals and the correlation of data-driven signals was

Determination of Respiratory Motion for Distal Esophagus Cancer Using Four-Dimensional Computed Tomography

International Nuclear Information System (INIS)

Yaremko, Brian P.; Guerrero, Thomas M.; McAleer, Mary F.; Bucci, M. Kara; Noyola-Martinez, Josue M.S.; Nguyen, Linda T. C.; Balter, Peter A.; Guerra, Rudy; Komaki, Ritsuko; Liao Zhongxing

2008-01-01

Purpose: To investigate the motion characteristics of distal esophagus cancer primary tumors using four-dimensional computed tomography (4D CT). Methods and Materials: Thirty-one consecutive patients treated for esophagus cancer who received respiratory-gated 4D CT imaging for treatment planning were selected. Deformable image registration was used to map the full expiratory motion gross tumor volume (GTV) to the full-inspiratory CT image, allowing quantitative assessment of each voxel's displacement. These displacements were correlated with patient tumor and respiratory characteristics. Results: The mean (SE) tidal volume was 608 (73) mL. The mean GTV volume was 64.3 (10.7) mL on expiration and 64.1 (10.7) mL on inspiration (no significant difference). The mean tumor motion in the x-direction was 0.13 (0.006) cm (average of absolute values), in the y-direction 0.23 (0.01) cm (anteriorly), and in the z-direction 0.71 (0.02) cm (inferiorly). Tumor motion correlated with tidal volume. Comparison of tumor motion above vs. below the diaphragm was significant for the average net displacement (p = 0.014), motion below the diaphragm was greater than above. From the cumulative distribution 95% of the tumors moved less than 0.80 cm radially and 1.75 cm inferiorly. Conclusions: Primary esophagus tumor motion was evaluated with 4D CT. According to the results of this study, when 4D CT is not available, a radial margin of 0.8 cm and axial margin of ±1.8 cm would provide tumor motion coverage for 95% of the cases in our study population

Optical surface scanning for respiratory motion monitoring in radiotherapy: a feasibility study

DEFF Research Database (Denmark)

Bekke, Susanne Lise; Mahmood, Faisal; Helt-Hansen, Jakob

2014-01-01

Purpose. We evaluated the feasibility of a surface scanning system (Catalyst) for respiratory motion monitoring of breast cancer patients treated with radiotherapy in deep inspiration breath-hold (DIBH). DIBH is used to reduce the radiation dose to the heart and lung. In contrast to RPM, a compet......Purpose. We evaluated the feasibility of a surface scanning system (Catalyst) for respiratory motion monitoring of breast cancer patients treated with radiotherapy in deep inspiration breath-hold (DIBH). DIBH is used to reduce the radiation dose to the heart and lung. In contrast to RPM...... and 3: the Quasar phantom was used to study if the angle of the monitored surface affects the amplitude of the recorded signal. Results. Experiment 1: we observed comparable period estimates for both systems. The amplitudes were 8 ± 0.1 mm (Catalyst) and 4.9 ± 0.1 mm (RPM). Independent check with in...... 1. Experiment 3: an increased (fixed) surface angle during breathing motion resulted in an overestimated amplitude with RPM, while the amplitude estimated by Catalyst was unaffected. Conclusion. Our study showed that Catalyst can be used as a better alternative to the RPM. With Catalyst...

Differences in baseline factors and survival between normocapnia, compensated respiratory acidosis and decompensated respiratory acidosis in COPD exacerbation: A pilot study.

Science.gov (United States)

Lun, Chung-Tat; Tsui, Miranda S N; Cheng, Suet-Lai; Chan, Veronica L; Leung, Wah-Shing; Cheung, Alice P S; Chu, Chung-Ming

2016-01-01

Patients with chronic obstructive pulmonary disease (COPD) experiencing acute exacerbation (AE-COPD) with decompensated respiratory acidosis are known to have poor outcomes in terms of recurrent respiratory failure and death. However, the outcomes of AE-COPD patients with compensated respiratory acidosis are not known. We performed a 1-year prospective, single-centre, cohort study in patients surviving the index admission for AE-COPD to compare baseline factors between groups with normocapnia, compensated respiratory acidosis and decompensated respiratory acidosis. Survival analysis was done to examine time to readmissions, life-threatening events and death. A total of 250 patients fulfilling the inclusion and exclusion criteria were recruited and 245 patients were analysed. Compared with normocapnia, both compensated and decompensated respiratory acidosis are associated with lower FEV1 % (P respiratory acidosis, there was no difference in FEV1 (% predicted) (P = 0.15), GOLD stage (P = 0.091), BODE index (P = 0.158) or time to life-threatening events (P = 0.301). High PaCO2 level (P = 0.002) and previous use of non-invasive ventilation (NIV) in acute setting (P respiratory acidosis are associated with poorer lung function and higher risk of future life-threatening events. High PaCO2 level and past history of NIV use in acute settings were predictive factors for future life-threatening events. Compensated respiratory acidosis warrants special attention and optimization of medical therapy as it poses risk of life-threatening events. © 2015 Asian Pacific Society of Respirology.

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

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

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

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

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

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

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

Prediction and classification of respiratory motion

CERN Document Server

Lee, Suk Jin

2014-01-01

This book describes recent radiotherapy technologies including tools for measuring target position during radiotherapy and tracking-based delivery systems. This book presents a customized prediction of respiratory motion with clustering from multiple patient interactions. The proposed method contributes to the improvement of patient treatments by considering breathing pattern for the accurate dose calculation in radiotherapy systems. Real-time tumor-tracking, where the prediction of irregularities becomes relevant, has yet to be clinically established. The statistical quantitative modeling for irregular breathing classification, in which commercial respiration traces are retrospectively categorized into several classes based on breathing pattern are discussed as well. The proposed statistical classification may provide clinical advantages to adjust the dose rate before and during the external beam radiotherapy for minimizing the safety margin. In the first chapter following the Introduction  to this book, we...

Leveraging respiratory organ motion for non-invasive tumor treatment devices: a feasibility study

Science.gov (United States)

Möri, Nadia; Jud, Christoph; Salomir, Rares; Cattin, Philippe C.

2016-06-01

In noninvasive abdominal tumor treatment, research has focused on minimizing organ motion either by gating, breath holding or tracking of the target. The paradigm shift proposed in this study takes advantage of the respiratory organ motion to passively scan the tumor. In the proposed self-scanning method, the focal point of the HIFU device is held fixed for a given time, while it passively scans the tumor due to breathing motion. The aim of this paper is to present a treatment planning method for such a system and show by simulation its feasibility. The presented planning method minimizes treatment time and ensures complete tumor ablation under free-breathing. We simulated our method on realistic motion patterns from a patient specific statistical respiratory model. With our method, we achieved a shorter treatment time than with the gold-standard motion-compensation approach. The main advantage of the proposed method is that electrically steering of the focal spot is no longer needed. As a consequence, it is much easier to find an optimal solution for both avoiding near field heating and covering the whole tumor. However, the reduced complexity on the beam forming comes at the price of an increased complexity on the planning side as well as a reduced efficiency in the energy distribution. Although we simulate the approach on HIFU, the idea of self-scanning passes over to other tumor treatment modalities such as proton therapy or classical radiation therapy.

Apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing helical chest computed tomography angiography.

Directory of Open Access Journals (Sweden)

Ioannis Pneumatikos

2008-10-01

Full Text Available Respiratory motion artifact in intubated and mechanically ventilated patients often reduces the quality of helical computed tomography pulmonary angiography (CTPA. Apneic oxygenation is a well established intra-operative technique that allows adequate oxygenation for short periods (up to 10 min in sedated and paralyzed patients. We describe the use of the apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing helical chest computed tomography angiography.

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

Dynamic PET image reconstruction integrating temporal regularization associated with respiratory motion correction for applications in oncology

Science.gov (United States)

Merlin, Thibaut; Visvikis, Dimitris; Fernandez, Philippe; Lamare, Frédéric

2018-02-01

Respiratory motion reduces both the qualitative and quantitative accuracy of PET images in oncology. This impact is more significant for quantitative applications based on kinetic modeling, where dynamic acquisitions are associated with limited statistics due to the necessity of enhanced temporal resolution. The aim of this study is to address these drawbacks, by combining a respiratory motion correction approach with temporal regularization in a unique reconstruction algorithm for dynamic PET imaging. Elastic transformation parameters for the motion correction are estimated from the non-attenuation-corrected PET images. The derived displacement matrices are subsequently used in a list-mode based OSEM reconstruction algorithm integrating a temporal regularization between the 3D dynamic PET frames, based on temporal basis functions. These functions are simultaneously estimated at each iteration, along with their relative coefficients for each image voxel. Quantitative evaluation has been performed using dynamic FDG PET/CT acquisitions of lung cancer patients acquired on a GE DRX system. The performance of the proposed method is compared with that of a standard multi-frame OSEM reconstruction algorithm. The proposed method achieved substantial improvements in terms of noise reduction while accounting for loss of contrast due to respiratory motion. Results on simulated data showed that the proposed 4D algorithms led to bias reduction values up to 40% in both tumor and blood regions for similar standard deviation levels, in comparison with a standard 3D reconstruction. Patlak parameter estimations on reconstructed images with the proposed reconstruction methods resulted in 30% and 40% bias reduction in the tumor and lung region respectively for the Patlak slope, and a 30% bias reduction for the intercept in the tumor region (a similar Patlak intercept was achieved in the lung area). Incorporation of the respiratory motion correction using an elastic model along with a

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

International Nuclear Information System (INIS)

Bowen, S R; Nyflot, M J; Meyer, J; Sandison, G A; Herrmann, C; Groh, C M; Wollenweber, S D; Stearns, C W; Kinahan, P E

2015-01-01

Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [ 18 F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/B mean ) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10–20%, treatment planning errors were 5–10%, and treatment delivery errors were 5–30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5–10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT

Radiotherapy of tumors under respiratory motion. Estimation of the motional velocity field and dose accumulation based on 4D image data

International Nuclear Information System (INIS)

Werner, Rene

2013-01-01

Respiratory motion represents a major challenge in radiation therapy in general, and especially for the therapy of lung tumors. In recent years and due to the introduction of modern techniques to 'acquire temporally resolved computed tomography images (4D CT images), different approaches have been developed to explicitly account for breathing motion during treatment. An integral component of such approaches is the concept of motion field estimation, which aims at a mathematical description and the computation of the motion sequences represented by the patient's images. As part of a 4D dose calculation/dose accumulation, the resulting vector fields are applied for assessing and accounting for breathing-induced effects on the dose distribution to be delivered. The reliability of related 4D treatment planning concepts is therefore directly tailored to the precision of the underlying motion field estimation process. Taking this into account, the thesis aims at developing optimized methods for the estimation of motion fields using 4D CT images and applying the resulting methods for the analysis of breathing induced dosimetric effects in radiation therapy. The thesis is subdivided into three parts that thematically build upon each other. The first part of the thesis is about the implementation, evaluation and optimization of methods for motion field estimation with the goal of precisely assessing respiratory motion of anatomical and pathological structures represented in a patient's 4D er image sequence; this step is the basis of subsequent developments and analysis parts. Especially non-linear registration techniques prove to be well suited to this purpose. After being optimized for the particular problem at hand, it is shown as part of an extensive multi-criteria evaluation study and additionally taking into account publicly accessible evaluation platforms that such methods allow estimating motion fields with subvoxel accuracy - which means that the developed methods

Dual respiratory and cardiac motion estimation in PET imaging: Methods design and quantitative evaluation.

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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

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

Intrafractional baseline drift during free breathing breast cancer radiation therapy.

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Jensen, Christer Andre; Acosta Roa, Ana María; Lund, Jo-Åsmund; Frengen, Jomar

2017-06-01

Intrafraction motion in breast cancer radiation therapy (BCRT) has not yet been thoroughly described in the literature. It has been observed that baseline drift occurs as part of the intrafraction motion. This study aims to measure baseline drift and its incidence in free-breathing BCRT patients using an in-house developed laser system for tracking the position of the sternum. Baseline drift was monitored in 20 right-sided breast cancer patients receiving free breathing 3D-conformal RT by using an in-house developed laser system which measures one-dimensional distance in the AP direction. A total of 357 patient respiratory traces from treatment sessions were logged and analysed. Baseline drift was compared to patient positioning error measured from in-field portal imaging. The mean overall baseline drift at end of treatment sessions was -1.3 mm for the patient population. Relatively small baseline drift was observed during the first fraction; however it was clearly detected already at the second fraction. Over 90% of the baseline drift occurs during the first 3 min of each treatment session. The baseline drift rate for the population was -0.5 ± 0.2 mm/min in the posterior direction the first minute after localization. Only 4% of the treatment sessions had a 5 mm or larger baseline drift at 5 min, all towards the posterior direction. Mean baseline drift in the posterior direction in free breathing BCRT was observed in 18 of 20 patients over all treatment sessions. This study shows that there is a substantial baseline drift in free breathing BCRT patients. No clear baseline drift was observed during the first treatment session; however, baseline drift was markedly present at the rest of the sessions. Intrafraction motion due to baseline drift should be accounted for in margin calculations.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study.

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Bowen, S R; Nyflot, M J; Herrmann, C; Groh, C M; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-05-07

Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [(18)F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude

Impact of respiratory motion correction and spatial resolution on lesion detection in PET: a simulation study based on real MR dynamic data

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Polycarpou, Irene; Tsoumpas, Charalampos; King, Andrew P.; Marsden, Paul K.

2014-02-01

The aim of this study is to investigate the impact of respiratory motion correction and spatial resolution on lesion detectability in PET as a function of lesion size and tracer uptake. Real respiratory signals describing different breathing types are combined with a motion model formed from real dynamic MR data to simulate multiple dynamic PET datasets acquired from a continuously moving subject. Lung and liver lesions were simulated with diameters ranging from 6 to 12 mm and lesion to background ratio ranging from 3:1 to 6:1. Projection data for 6 and 3 mm PET scanner resolution were generated using analytic simulations and reconstructed without and with motion correction. Motion correction was achieved using motion compensated image reconstruction. The detectability performance was quantified by a receiver operating characteristic (ROC) analysis obtained using a channelized Hotelling observer and the area under the ROC curve (AUC) was calculated as the figure of merit. The results indicate that respiratory motion limits the detectability of lung and liver lesions, depending on the variation of the breathing cycle length and amplitude. Patients with large quiescent periods had a greater AUC than patients with regular breathing cycles and patients with long-term variability in respiratory cycle or higher motion amplitude. In addition, small (less than 10 mm diameter) or low contrast (3:1) lesions showed the greatest improvement in AUC as a result of applying motion correction. In particular, after applying motion correction the AUC is improved by up to 42% with current PET resolution (i.e. 6 mm) and up to 51% for higher PET resolution (i.e. 3 mm). Finally, the benefit of increasing the scanner resolution is small unless motion correction is applied. This investigation indicates high impact of respiratory motion correction on lesion detectability in PET and highlights the importance of motion correction in order to benefit from the increased resolution of future

Impact of respiratory motion correction and spatial resolution on lesion detection in PET: a simulation study based on real MR dynamic data

International Nuclear Information System (INIS)

Polycarpou, Irene; Tsoumpas, Charalampos; King, Andrew P; Marsden, Paul K

2014-01-01

The aim of this study is to investigate the impact of respiratory motion correction and spatial resolution on lesion detectability in PET as a function of lesion size and tracer uptake. Real respiratory signals describing different breathing types are combined with a motion model formed from real dynamic MR data to simulate multiple dynamic PET datasets acquired from a continuously moving subject. Lung and liver lesions were simulated with diameters ranging from 6 to 12 mm and lesion to background ratio ranging from 3:1 to 6:1. Projection data for 6 and 3 mm PET scanner resolution were generated using analytic simulations and reconstructed without and with motion correction. Motion correction was achieved using motion compensated image reconstruction. The detectability performance was quantified by a receiver operating characteristic (ROC) analysis obtained using a channelized Hotelling observer and the area under the ROC curve (AUC) was calculated as the figure of merit. The results indicate that respiratory motion limits the detectability of lung and liver lesions, depending on the variation of the breathing cycle length and amplitude. Patients with large quiescent periods had a greater AUC than patients with regular breathing cycles and patients with long-term variability in respiratory cycle or higher motion amplitude. In addition, small (less than 10 mm diameter) or low contrast (3:1) lesions showed the greatest improvement in AUC as a result of applying motion correction. In particular, after applying motion correction the AUC is improved by up to 42% with current PET resolution (i.e. 6 mm) and up to 51% for higher PET resolution (i.e. 3 mm). Finally, the benefit of increasing the scanner resolution is small unless motion correction is applied. This investigation indicates high impact of respiratory motion correction on lesion detectability in PET and highlights the importance of motion correction in order to benefit from the increased resolution of future

Automated, simple, and efficient influenza RNA extraction from clinical respiratory swabs using TruTip and epMotion.

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Griesemer, Sara B; Holmberg, Rebecca; Cooney, Christopher G; Thakore, Nitu; Gindlesperger, Alissa; Knickerbocker, Christopher; Chandler, Darrell P; St George, Kirsten

2013-09-01

Rapid, simple and efficient influenza RNA purification from clinical samples is essential for sensitive molecular detection of influenza infection. Automation of the TruTip extraction method can increase sample throughput while maintaining performance. To automate TruTip influenza RNA extraction using an Eppendorf epMotion robotic liquid handler, and to compare its performance to the bioMerieux easyMAG and Qiagen QIAcube instruments. Extraction efficacy and reproducibility of the automated TruTip/epMotion protocol was assessed from influenza-negative respiratory samples spiked with influenza A and B viruses. Clinical extraction performance from 170 influenza A and B-positive respiratory swabs was also evaluated and compared using influenza A and B real-time RT-PCR assays. TruTip/epMotion extraction efficacy was 100% in influenza virus-spiked samples with at least 745 influenza A and 370 influenza B input gene copies per extraction, and exhibited high reproducibility over four log10 concentrations of virus (extraction were also positive following TruTip extraction. Overall Ct value differences obtained between TruTip/epMotion and easyMAG/QIAcube clinical extracts ranged from 1.24 to 1.91. Pairwise comparisons of Ct values showed a high correlation of the TruTip/epMotion protocol to the other methods (R2>0.90). The automated TruTip/epMotion protocol is a simple and rapid extraction method that reproducibly purifies influenza RNA from respiratory swabs, with comparable efficacy and efficiency to both the easyMAG and QIAcube instruments. Copyright © 2013 Elsevier B.V. All rights reserved.

LROC Investigation of Three Strategies for Reducing the Impact of Respiratory Motion on the Detection of Solitary Pulmonary Nodules in SPECT

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Smyczynski, Mark S.; Gifford, Howard C.; Dey, Joyoni; Lehovich, Andre; McNamara, Joseph E.; Segars, W. Paul; King, Michael A.

2016-02-01

The objective of this investigation was to determine the effectiveness of three motion reducing strategies in diminishing the degrading impact of respiratory motion on the detection of small solitary pulmonary nodules (SPNs) in single-photon emission computed tomographic (SPECT) imaging in comparison to a standard clinical acquisition and the ideal case of imaging in the absence of respiratory motion. To do this nonuniform rational B-spline cardiac-torso (NCAT) phantoms based on human-volunteer CT studies were generated spanning the respiratory cycle for a normal background distribution of Tc-99 m NeoTect. Similarly, spherical phantoms of 1.0-cm diameter were generated to model small SPN for each of the 150 uniquely located sites within the lungs whose respiratory motion was based on the motion of normal structures in the volunteer CT studies. The SIMIND Monte Carlo program was used to produce SPECT projection data from these. Normal and single-lesion containing SPECT projection sets with a clinically realistic Poisson noise level were created for the cases of 1) the end-expiration (EE) frame with all counts, 2) respiration-averaged motion with all counts, 3) one fourth of the 32 frames centered around EE (Quarter Binning), 4) one half of the 32 frames centered around EE (Half Binning), and 5) eight temporally binned frames spanning the respiratory cycle. Each of the sets of combined projection data were reconstructed with RBI-EM with system spatial-resolution compensation (RC). Based on the known motion for each of the 150 different lesions, the reconstructed volumes of respiratory bins were shifted so as to superimpose the locations of the SPN onto that in the first bin (Reconstruct and Shift). Five human observers performed localization receiver operating characteristics (LROC) studies of SPN detection. The observer results were analyzed for statistical significance differences in SPN detection accuracy among the three correction strategies, the standard

Difference in target definition using three different methods to include respiratory motion in radiotherapy of lung cancer.

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Sloth Møller, Ditte; Knap, Marianne Marquard; Nyeng, Tine Bisballe; Khalil, Azza Ahmed; Holt, Marianne Ingerslev; Kandi, Maria; Hoffmann, Lone

2017-11-01

Minimizing the planning target volume (PTV) while ensuring sufficient target coverage during the entire respiratory cycle is essential for free-breathing radiotherapy of lung cancer. Different methods are used to incorporate the respiratory motion into the PTV. Fifteen patients were analyzed. Respiration can be included in the target delineation process creating a respiratory GTV, denoted iGTV. Alternatively, the respiratory amplitude (A) can be measured based on the 4D-CT and A can be incorporated in the margin expansion. The GTV expanded by A yielded GTV + resp, which was compared to iGTV in terms of overlap. Three methods for PTV generation were compared. PTV del (delineated iGTV expanded to CTV plus PTV margin), PTV σ (GTV expanded to CTV and A was included as a random uncertainty in the CTV to PTV margin) and PTV ∑ (GTV expanded to CTV, succeeded by CTV linear expansion by A to CTV + resp, which was finally expanded to PTV ∑ ). Deformation of tumor and lymph nodes during respiration resulted in volume changes between the respiratory phases. The overlap between iGTV and GTV + resp showed that on average 7% of iGTV was outside the GTV + resp implying that GTV + resp did not capture the tumor during the full deformable respiration cycle. A comparison of the PTV volumes showed that PTV σ was smallest and PTV Σ largest for all patients. PTV σ was in mean 14% (31 cm 3 ) smaller than PTV del , while PTV del was 7% (20 cm 3 ) smaller than PTV Σ . PTV σ yields the smallest volumes but does not ensure coverage of tumor during the full respiratory motion due to tumor deformation. Incorporating the respiratory motion in the delineation (PTV del ) takes into account the entire respiratory cycle including deformation, but at the cost, however, of larger treatment volumes. PTV Σ should not be used, since it incorporates the disadvantages of both PTV del and PTV σ .

Accuracy of respiratory motion measurement of 4D-MRI: A comparison between cine and sequential acquisition.

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Liu, Yilin; Yin, Fang-Fang; Rhee, DongJoo; Cai, Jing

2016-01-01

The authors have recently developed a cine-mode T2*/T1-weighted 4D-MRI technique and a sequential-mode T2-weighted 4D-MRI technique for imaging respiratory motion. This study aims at investigating which 4D-MRI image acquisition mode, cine or sequential, provides more accurate measurement of organ motion during respiration. A 4D digital extended cardiac-torso (XCAT) human phantom with a hypothesized tumor was used to simulate the image acquisition and the 4D-MRI reconstruction. The respiratory motion was controlled by the given breathing signal profiles. The tumor was manipulated to move continuously with the surrounding tissue. The motion trajectories were measured from both sequential- and cine-mode 4D-MRI images. The measured trajectories were compared with the average trajectory calculated from the input profiles, which was used as references. The error in 4D-MRI tumor motion trajectory (E) was determined. In addition, the corresponding respiratory motion amplitudes of all the selected 2D images for 4D reconstruction were recorded. Each of the amplitude was compared with the amplitude of its associated bin on the average breathing curve. The mean differences from the average breathing curve across all slice positions (D) were calculated. A total of 500 simulated respiratory profiles with a wide range of irregularity (Ir) were used to investigate the relationship between D and Ir. Furthermore, statistical analysis of E and D using XCAT controlled by 20 cancer patients' breathing profiles was conducted. Wilcoxon Signed Rank test was conducted to compare two modes. D increased faster for cine-mode (D = 1.17 × Ir + 0.23) than sequential-mode (D = 0.47 × Ir + 0.23) as irregularity increased. For the XCAT study using 20 cancer patients' breathing profiles, the median E values were significantly different: 0.12 and 0.10 cm for cine- and sequential-modes, respectively, with a p-value of 0.02. The median D values were significantly different: 0.47 and 0.24 cm for cine

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.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

Science.gov (United States)

Bowen, S R; Nyflot, M J; Hermann, C; Groh, C; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-01-01

Effective positron emission tomography/computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by 6 different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy (VMAT) were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses (EUD), and 2%-2mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10–20%, treatment planning errors were 5–10%, and treatment delivery errors were 5–30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5–10% in PET/CT imaging, PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the

A telemedicine instrument for Internet-based home monitoring of thoracoabdominal motion in patients with respiratory diseases

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da Silva Junior, Evert Pereira; Esteves, Guilherme Pompeu; Dames, Karla Kristine; Melo, Pedro Lopes de

2011-01-01

Changes in thoracoabdominal motion are highly prevalent in patients with chronic respiratory diseases. Home care services that use telemedicine techniques and Internet-based monitoring have the potential to improve the management of these patients. However, there is no detailed description in the literature of a system for Internet-based monitoring of patients with disturbed thoracoabdominal motion. The purpose of this work was to describe the development of a new telemedicine instrument for Internet-based home monitoring of thoracoabdominal movement. The instrument directly measures changes in the thorax and abdomen circumferences and transfers data through a transmission control protocol/Internet protocol connection. After the design details are described, the accuracy of the electronic and software processing units of the instrument is evaluated by using electronic signals simulating normal subjects and individuals with thoracoabdominal motion disorders. The results obtained during in vivo studies on normal subjects simulating thoracoabdominal motion disorders showed that this new system is able to detect a reduction in abdominal movement that is associated with abnormal thoracic breathing (p telemedicine scenarios, which can reduce the costs of assistance offered to patients with respiratory diseases.

Respiratory liver motion tracking during transcatheter procedures using guidewire detection

International Nuclear Information System (INIS)

Vanegas Orozco, Maria-Carolina; Gorges, Sebastien; Pescatore, Jeremie

2008-01-01

Transcatheter chemoembolization of liver tumors is performed under X-ray fluoroscopic image guidance. This is a difficult procedure because the vessels of the liver are constantly moving due to respiration and they are not visible in the X-ray image unless a contrast medium is injected. In order to help the interventional radiologist during the treatment, we propose to superimpose on to the fluoroscopic image a pre-acquired contrast-enhanced 2D or 3D image while accounting for liver motion. Our approach proposes to track the guidewire from frame to frame. Our proposed method can be split into two steps. First the guidewire is automatically detected; then the motion between two frames is estimated using a robust ICP (iterative closest point) algorithm. We have tested our method on simulated X-ray fluoroscopic images of a moving guidewire and applied it on 4 clinical sequences. Simulation demonstrated that the mean precision of our method is inferior to 1 mm. On clinical data, preliminary results demonstrated that this method allows for respiratory motion compensation of liver vessels with a mean accuracy inferior to 3 mm. (orig.)

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

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

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.

Kernel density estimation-based real-time prediction for respiratory motion

International Nuclear Information System (INIS)

Ruan, Dan

2010-01-01

Effective delivery of adaptive radiotherapy requires locating the target with high precision in real time. System latency caused by data acquisition, streaming, processing and delivery control necessitates prediction. Prediction is particularly challenging for highly mobile targets such as thoracic and abdominal tumors undergoing respiration-induced motion. The complexity of the respiratory motion makes it difficult to build and justify explicit models. In this study, we honor the intrinsic uncertainties in respiratory motion and propose a statistical treatment of the prediction problem. Instead of asking for a deterministic covariate-response map and a unique estimate value for future target position, we aim to obtain a distribution of the future target position (response variable) conditioned on the observed historical sample values (covariate variable). The key idea is to estimate the joint probability distribution (pdf) of the covariate and response variables using an efficient kernel density estimation method. Then, the problem of identifying the distribution of the future target position reduces to identifying the section in the joint pdf based on the observed covariate. Subsequently, estimators are derived based on this estimated conditional distribution. This probabilistic perspective has some distinctive advantages over existing deterministic schemes: (1) it is compatible with potentially inconsistent training samples, i.e., when close covariate variables correspond to dramatically different response values; (2) it is not restricted by any prior structural assumption on the map between the covariate and the response; (3) the two-stage setup allows much freedom in choosing statistical estimates and provides a full nonparametric description of the uncertainty for the resulting estimate. We evaluated the prediction performance on ten patient RPM traces, using the root mean squared difference between the prediction and the observed value normalized by the

Respiratory Motion Correction for Compressively Sampled Free Breathing Cardiac MRI Using Smooth l1-Norm Approximation

Directory of Open Access Journals (Sweden)

Muhammad Bilal

2018-01-01

Full Text Available Transformed domain sparsity of Magnetic Resonance Imaging (MRI has recently been used to reduce the acquisition time in conjunction with compressed sensing (CS theory. Respiratory motion during MR scan results in strong blurring and ghosting artifacts in recovered MR images. To improve the quality of the recovered images, motion needs to be estimated and corrected. In this article, a two-step approach is proposed for the recovery of cardiac MR images in the presence of free breathing motion. In the first step, compressively sampled MR images are recovered by solving an optimization problem using gradient descent algorithm. The L1-norm based regularizer, used in optimization problem, is approximated by a hyperbolic tangent function. In the second step, a block matching algorithm, known as Adaptive Rood Pattern Search (ARPS, is exploited to estimate and correct respiratory motion among the recovered images. The framework is tested for free breathing simulated and in vivo 2D cardiac cine MRI data. Simulation results show improved structural similarity index (SSIM, peak signal-to-noise ratio (PSNR, and mean square error (MSE with different acceleration factors for the proposed method. Experimental results also provide a comparison between k-t FOCUSS with MEMC and the proposed method.

A Novel Respiratory Motion Perturbation Model Adaptable to Patient Breathing Irregularities

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Yuan, Amy [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York (United States); Wei, Jie [Department of Computer Science, City College of New York, New York, New York (United States); Gaebler, Carl P.; Huang, Hailiang; Olek, Devin [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York (United States); Li, Guang, E-mail: lig2@mskcc.org [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York (United States)

2016-12-01

Purpose: To develop a physical, adaptive motion perturbation model to predict tumor motion using feedback from dynamic measurement of breathing conditions to compensate for breathing irregularities. Methods and Materials: A novel respiratory motion perturbation (RMP) model was developed to predict tumor motion variations caused by breathing irregularities. This model contained 2 terms: the initial tumor motion trajectory, measured from 4-dimensional computed tomography (4DCT) images, and motion perturbation, calculated from breathing variations in tidal volume (TV) and breathing pattern (BP). The motion perturbation was derived from the patient-specific anatomy, tumor-specific location, and time-dependent breathing variations. Ten patients were studied, and 2 amplitude-binned 4DCT images for each patient were acquired within 2 weeks. The motion trajectories of 40 corresponding bifurcation points in both 4DCT images of each patient were obtained using deformable image registration. An in-house 4D data processing toolbox was developed to calculate the TV and BP as functions of the breathing phase. The motion was predicted from the simulation 4DCT scan to the treatment 4DCT scan, and vice versa, resulting in 800 predictions. For comparison, noncorrected motion differences and the predictions from a published 5-dimensional model were used. Results: The average motion range in the superoinferior direction was 9.4 ± 4.4 mm, the average ΔTV ranged from 10 to 248 mm{sup 3} (−26% to 61%), and the ΔBP ranged from 0 to 0.2 (−71% to 333%) between the 2 4DCT scans. The mean noncorrected motion difference was 2.0 ± 2.8 mm between 2 4DCT motion trajectories. After applying the RMP model, the mean motion difference was reduced significantly to 1.2 ± 1.8 mm (P=.0018), a 40% improvement, similar to the 1.2 ± 1.8 mm (P=.72) predicted with the 5-dimensional model. Conclusions: A novel physical RMP model was developed with an average accuracy of 1.2 ± 1.8 mm for

Simulation of range imaging-based estimation of respiratory lung motion. Influence of noise, signal dimensionality and sampling patterns.

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Wilms, M; Werner, R; Blendowski, M; Ortmüller, J; Handels, H

2014-01-01

A major problem associated with the irradiation of thoracic and abdominal tumors is respiratory motion. In clinical practice, motion compensation approaches are frequently steered by low-dimensional breathing signals (e.g., spirometry) and patient-specific correspondence models, which are used to estimate the sought internal motion given a signal measurement. Recently, the use of multidimensional signals derived from range images of the moving skin surface has been proposed to better account for complex motion patterns. In this work, a simulation study is carried out to investigate the motion estimation accuracy of such multidimensional signals and the influence of noise, the signal dimensionality, and different sampling patterns (points, lines, regions). A diffeomorphic correspondence modeling framework is employed to relate multidimensional breathing signals derived from simulated range images to internal motion patterns represented by diffeomorphic non-linear transformations. Furthermore, an automatic approach for the selection of optimal signal combinations/patterns within this framework is presented. This simulation study focuses on lung motion estimation and is based on 28 4D CT data sets. The results show that the use of multidimensional signals instead of one-dimensional signals significantly improves the motion estimation accuracy, which is, however, highly affected by noise. Only small differences exist between different multidimensional sampling patterns (lines and regions). Automatically determined optimal combinations of points and lines do not lead to accuracy improvements compared to results obtained by using all points or lines. Our results show the potential of multidimensional breathing signals derived from range images for the model-based estimation of respiratory motion in radiation therapy.

The development of equipment for the technical assessment of respiratory motion induced artefacts in MRI

International Nuclear Information System (INIS)

Jackson, P.C.; Davies, S.C.; Zananiri, F.V.; Follett, D.H.; Halliwell, M.; Wells, P.N.T.; Bean, J.P.

1993-01-01

A device and technique to study the effects of respiratory motion on the quality of magnetic resonance images is proposed. The construction of the device enables a variety of test objects to be mounted and used in the evaluation of imaging parameters that may be affected by motion. The equipment is constructed of cast acrylic and the movement is actuated and controlled pneumatically thus ensuring that there are no interactions with the magnetic field and radiofrequency detection system to cause further image artefacts. Separate studies have been performed, using ultrasound, to assess the degree and rate of movement of organs owing to respiration in order to derive the motion parameters for the apparatus. Preliminary results indicate that the technique produces motion induced artefacts simulating those which are the result of the effects of respiration. (author)

Dosimetric consequences of tumour motion due to respiration for a scanned proton beam

International Nuclear Information System (INIS)

Kraus, K M; Oelfke, U; Heath, E

2011-01-01

A method for simulating spot-scanned delivery to a moving tumour was developed which uses patient-specific image and plan data. The magnitude of interplay effects was investigated for two patient cases under different fractionation and respiratory motion variation scenarios. The use of volumetric rescanning for motion mitigation was also investigated. For different beam arrangements, interplay effects lead to severely distorted dose distributions for a single fraction delivery. Baseline shift variations for single fraction delivery reduced the dose to the clinical target volume (CTV) by up to 14.1 Gy. Fractionated delivery significantly reduced interplay effects; however, local overdosage of 12.3% compared to the statically delivered dose remained for breathing period variations. Variations of the tumour baseline position and respiratory period were found to have the largest influence on target inhomogeneity; these effects were reduced with fractionation. Volumetric rescanning improved the dose homogeneity. For the CTV, underdosage was improved by up to 34% in the CTV and overdosage to the lung was reduced by 6%. Our results confirm that rescanning potentially increases the dose homogeneity; however, it might not sufficiently compensate motion-induced dose distortions. Other motion mitigation techniques may be required to additionally treat lung tumours with scanned proton beams.

Development of a robust and cost-effective 3D respiratory motion monitoring system using the kinect device: Accuracy comparison with the conventional stereovision navigation system.

Science.gov (United States)

Bae, Myungsoo; Lee, Sangmin; Kim, Namkug

2018-07-01

To develop and validate a robust and cost-effective 3D respiratory monitoring system based on a Kinect device with a custom-made simple marker. A 3D respiratory monitoring system comprising the simple marker and the Microsoft Kinect v2 device was developed. The marker was designed for simple and robust detection, and the tracking algorithm was developed using the depth, RGB, and infra-red images acquired from the Kinect sensor. A Kalman filter was used to suppress movement noises. The major movements of the marker attached to the four different locations of body surface were determined from the initially collected tracking points of the marker while breathing. The signal level of respiratory motion with the tracking point was estimated along the major direction vector. The accuracy of the results was evaluated through a comparison with those of the conventional stereovision navigation system (NDI Polaris Spectra). Sixteen normal volunteers were enrolled to evaluate the accuracy of this system. The correlation coefficients between the respiratory motion signal from the Kinect device and conventional navigation system ranged from 0.970 to 0.999 and from 0.837 to 0.995 at the abdominal and thoracic surfaces, respectively. The respiratory motion signal from this system was obtained at 27-30 frames/s. This system with the Kinect v2 device and simple marker could be used for cost-effective, robust and accurate 3D respiratory motion monitoring. In addition, this system is as reliable for respiratory motion signal generation and as practically useful as the conventional stereovision navigation system and is less sensitive to patient posture. Copyright © 2018 Elsevier B.V. All rights reserved.

Real-time prediction of respiratory motion based on a local dynamic model in an augmented space.

Science.gov (United States)

Hong, S-M; Jung, B-H; Ruan, D

2011-03-21

Motion-adaptive radiotherapy aims to deliver ablative radiation dose to the tumor target with minimal normal tissue exposure, by accounting for real-time target movement. In practice, prediction is usually necessary to compensate for system latency induced by measurement, communication and control. This work focuses on predicting respiratory motion, which is most dominant for thoracic and abdominal tumors. We develop and investigate the use of a local dynamic model in an augmented space, motivated by the observation that respiratory movement exhibits a locally circular pattern in a plane augmented with a delayed axis. By including the angular velocity as part of the system state, the proposed dynamic model effectively captures the natural evolution of respiratory motion. The first-order extended Kalman filter is used to propagate and update the state estimate. The target location is predicted by evaluating the local dynamic model equations at the required prediction length. This method is complementary to existing work in that (1) the local circular motion model characterizes 'turning', overcoming the limitation of linear motion models; (2) it uses a natural state representation including the local angular velocity and updates the state estimate systematically, offering explicit physical interpretations; (3) it relies on a parametric model and is much less data-satiate than the typical adaptive semiparametric or nonparametric method. We tested the performance of the proposed method with ten RPM traces, using the normalized root mean squared difference between the predicted value and the retrospective observation as the error metric. Its performance was compared with predictors based on the linear model, the interacting multiple linear models and the kernel density estimator for various combinations of prediction lengths and observation rates. The local dynamic model based approach provides the best performance for short to medium prediction lengths under relatively

Predicting respiratory motion signals for image-guided radiotherapy using multi-step linear methods (MULIN)

International Nuclear Information System (INIS)

Ernst, Floris; Schweikard, Achim

2008-01-01

Forecasting of respiration motion in image-guided radiotherapy requires algorithms that can accurately and efficiently predict target location. Improved methods for respiratory motion forecasting were developed and tested. MULIN, a new family of prediction algorithms based on linear expansions of the prediction error, was developed and tested. Computer-generated data with a prediction horizon of 150 ms was used for testing in simulation experiments. MULIN was compared to Least Mean Squares-based predictors (LMS; normalized LMS, nLMS; wavelet-based multiscale autoregression, wLMS) and a multi-frequency Extended Kalman Filter (EKF) approach. The in vivo performance of the algorithms was tested on data sets of patients who underwent radiotherapy. The new MULIN methods are highly competitive, outperforming the LMS and the EKF prediction algorithms in real-world settings and performing similarly to optimized nLMS and wLMS prediction algorithms. On simulated, periodic data the MULIN algorithms are outperformed only by the EKF approach due to its inherent advantage in predicting periodic signals. In the presence of noise, the MULIN methods significantly outperform all other algorithms. The MULIN family of algorithms is a feasible tool for the prediction of respiratory motion, performing as well as or better than conventional algorithms while requiring significantly lower computational complexity. The MULIN algorithms are of special importance wherever high-speed prediction is required. (orig.)

Predicting respiratory motion signals for image-guided radiotherapy using multi-step linear methods (MULIN)

Energy Technology Data Exchange (ETDEWEB)

Ernst, Floris; Schweikard, Achim [University of Luebeck, Institute for Robotics and Cognitive Systems, Luebeck (Germany)

2008-06-15

Forecasting of respiration motion in image-guided radiotherapy requires algorithms that can accurately and efficiently predict target location. Improved methods for respiratory motion forecasting were developed and tested. MULIN, a new family of prediction algorithms based on linear expansions of the prediction error, was developed and tested. Computer-generated data with a prediction horizon of 150 ms was used for testing in simulation experiments. MULIN was compared to Least Mean Squares-based predictors (LMS; normalized LMS, nLMS; wavelet-based multiscale autoregression, wLMS) and a multi-frequency Extended Kalman Filter (EKF) approach. The in vivo performance of the algorithms was tested on data sets of patients who underwent radiotherapy. The new MULIN methods are highly competitive, outperforming the LMS and the EKF prediction algorithms in real-world settings and performing similarly to optimized nLMS and wLMS prediction algorithms. On simulated, periodic data the MULIN algorithms are outperformed only by the EKF approach due to its inherent advantage in predicting periodic signals. In the presence of noise, the MULIN methods significantly outperform all other algorithms. The MULIN family of algorithms is a feasible tool for the prediction of respiratory motion, performing as well as or better than conventional algorithms while requiring significantly lower computational complexity. The MULIN algorithms are of special importance wherever high-speed prediction is required. (orig.)

Audiovisual biofeedback improves the correlation between internal/external surrogate motion and lung tumor motion.

Science.gov (United States)

Lee, Danny; Greer, Peter B; Paganelli, Chiara; Ludbrook, Joanna Jane; Kim, Taeho; Keall, Paul

2018-03-01

Breathing management can reduce breath-to-breath (intrafraction) and day-by-day (interfraction) variability in breathing motion while utilizing the respiratory motion of internal and external surrogates for respiratory guidance. Audiovisual (AV) biofeedback, an interactive personalized breathing motion management system, has been developed to improve reproducibility of intra- and interfraction breathing motion. However, the assumption of the correlation of respiratory motion between surrogates and tumors is not always verified during medical imaging and radiation treatment. Therefore, the aim of the study was to test the hypothesis that the correlation of respiratory motion between surrogates and tumors is the same under free breathing without guidance (FB) and with AV biofeedback guidance for voluntary motion management. For 13 lung cancer patients receiving radiotherapy, 2D coronal and sagittal cine-MR images were acquired across two MRI sessions (pre- and mid-treatment) with two breathing conditions: (a) FB and (b) AV biofeedback, totaling 88 patient measurements. Simultaneously, the external respiratory motion of the abdomen was measured. The internal respiratory motion of the diaphragm and lung tumor was retrospectively measured from 2D coronal and sagittal cine-MR images. The correlation of respiratory motion between surrogates and tumors was calculated using Pearson's correlation coefficient for: (a) abdomen to tumor (abdomen-tumor) and (b) diaphragm to tumor (diaphragm-tumor). The correlations were compared between FB and AV biofeedback using several metrics: abdomen-tumor and diaphragm-tumor correlations with/without ≥5 mm tumor motion range and with/without adjusting for phase shifts between the signals. Compared to FB, AV biofeedback improved abdomen-tumor correlation by 11% (p = 0.12) from 0.53 to 0.59 and diaphragm-tumor correlation by 13% (p = 0.02) from 0.55 to 0.62. Compared to FB, AV biofeedback improved abdomen-tumor correlation by 17% (p = 0

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

A generalized framework unifying image registration and respiratory motion models and incorporating image reconstruction, for partial image data or full images

Science.gov (United States)

McClelland, Jamie R.; Modat, Marc; Arridge, Simon; Grimes, Helen; D'Souza, Derek; Thomas, David; O' Connell, Dylan; Low, Daniel A.; Kaza, Evangelia; Collins, David J.; Leach, Martin O.; Hawkes, David J.

2017-06-01

Surrogate-driven respiratory motion models relate the motion of the internal anatomy to easily acquired respiratory surrogate signals, such as the motion of the skin surface. They are usually built by first using image registration to determine the motion from a number of dynamic images, and then fitting a correspondence model relating the motion to the surrogate signals. In this paper we present a generalized framework that unifies the image registration and correspondence model fitting into a single optimization. This allows the use of ‘partial’ imaging data, such as individual slices, projections, or k-space data, where it would not be possible to determine the motion from an individual frame of data. Motion compensated image reconstruction can also be incorporated using an iterative approach, so that both the motion and a motion-free image can be estimated from the partial image data. The framework has been applied to real 4DCT, Cine CT, multi-slice CT, and multi-slice MR data, as well as simulated datasets from a computer phantom. This includes the use of a super-resolution reconstruction method for the multi-slice MR data. Good results were obtained for all datasets, including quantitative results for the 4DCT and phantom datasets where the ground truth motion was known or could be estimated.

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

Audiovisual biofeedback improves diaphragm motion reproducibility in MRI

Science.gov (United States)

Kim, Taeho; Pollock, Sean; Lee, Danny; O’Brien, Ricky; Keall, Paul

2012-01-01

Purpose: In lung radiotherapy, variations in cycle-to-cycle breathing results in four-dimensional computed tomography imaging artifacts, leading to inaccurate beam coverage and tumor targeting. In previous studies, the effect of audiovisual (AV) biofeedback on the external respiratory signal reproducibility has been investigated but the internal anatomy motion has not been fully studied. The aim of this study is to test the hypothesis that AV biofeedback improves diaphragm motion reproducibility of internal anatomy using magnetic resonance imaging (MRI). Methods: To test the hypothesis 15 healthy human subjects were enrolled in an ethics-approved AV biofeedback study consisting of two imaging sessions spaced ∼1 week apart. Within each session MR images were acquired under free breathing and AV biofeedback conditions. The respiratory signal to the AV biofeedback system utilized optical monitoring of an external marker placed on the abdomen. Synchronously, serial thoracic 2D MR images were obtained to measure the diaphragm motion using a fast gradient-recalled-echo MR pulse sequence in both coronal and sagittal planes. The improvement in the diaphragm motion reproducibility using the AV biofeedback system was quantified by comparing cycle-to-cycle variability in displacement, respiratory period, and baseline drift. Additionally, the variation in improvement between the two sessions was also quantified. Results: The average root mean square error (RMSE) of diaphragm cycle-to-cycle displacement was reduced from 2.6 mm with free breathing to 1.6 mm (38% reduction) with the implementation of AV biofeedback (p-value biofeedback (p-value biofeedback (p-value = 0.012). The diaphragm motion reproducibility improvements with AV biofeedback were consistent with the abdominal motion reproducibility that was observed from the external marker motion variation. Conclusions: This study was the first to investigate the potential of AV biofeedback to improve the motion

The impact of respiratory motion and treatment technique on stereotactic body radiation therapy for liver cancer

International Nuclear Information System (INIS)

Wu, Q. Jackie; Thongphiew, Danthai; Wang Zhiheng; Chankong, Vira; Yin Fangfang

2008-01-01

Stereotactic body radiation therapy (SBRT), which delivers a much higher fractional dose than conventional treatment in only a few fractions, is an effective treatment for liver metastases. For patients who are treated under free-breathing conditions, however, respiration-induced tumor motion in the liver is a concern. Limited clinical information is available related to the impact of tumor motion and treatment technique on the dosimetric consequences. This study evaluated the dosimetric deviations between planned and delivered SBRT dose in the presence of tumor motion for three delivery techniques: three-dimensional conformal static beams (3DCRT), dynamic conformal arc (DARC), and intensity-modulated radiation therapy (IMRT). Five cases treated with SBRT for liver metastases were included in the study, with tumor motions ranging from 0.5 to 1.75 cm. For each case, three different treatment plans were developed using 3DCRT, DARC, and IMRT. The gantry/multileaf collimator (MLC) motion in the DARC plans and the MLC motion in the IMRT plans were synchronized to the patient's respiratory motion. Retrospectively sorted four-dimensional computed tomography image sets were used to determine patient-organ motion and to calculate the dose delivered during each respiratory phase. Deformable registration, using thin-plate-spline models, was performed to encode the tumor motion and deformation and to register the dose-per-phase to the reference phase images. The different dose distributions resulting from the different delivery techniques and motion ranges were compared to assess the effect of organ motion on dose delivery. Voxel dose variations occurred mostly in the high gradient regions, typically between the target volume and normal tissues, with a maximum variation up to 20%. The greatest CTV variation of all the plans was seen in the IMRT technique with the largest motion range (D99: -8.9%, D95: -8.3%, and D90: -6.3%). The greatest variation for all 3DCRT plans was less

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.

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

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

Color structured light system of chest wall motion measurement for respiratory volume evaluation

Science.gov (United States)

Chen, Huijun; Cheng, Yuan; Liu, Dongdong; Zhang, Xiaodong; Zhang, Jue; Que, Chengli; Wang, Guangfa; Fang, Jing

2010-03-01

We present a structured light system to dynamically measure human chest wall motion for respiratory volume estimation. Based on a projection of an encoded color pattern and a few active markers attached to the trunk, respiratory volumes are obtained by evaluating the 3-D topographic changes of the chest wall in an anatomically consistent measuring region during respiration. Three measuring setups are established: a single-sided illuminating-recording setup for standing posture, an inclined single-sided setup for supine posture, and a double-sided setup for standing posture. Results are compared with the pneumotachography and show good agreement in volume estimations [correlation coefficient: R>0.99 (Pvolume during the isovolume maneuver (standard deviationpulmonary functional differences between the diseased and the contralateral sides of the thorax, and subsequent improvement of this imbalance after drainage. These results demonstrate the proposed optical method is capable of not only whole respiratory volume evaluation with high accuracy, but also regional pulmonary function assessment in different chest wall behaviors, with the advantage of whole-field measurement.

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.

Generation of fluoroscopic 3D images with a respiratory motion model based on an external surrogate signal

International Nuclear Information System (INIS)

Hurwitz, Martina; Williams, Christopher L; Mishra, Pankaj; Rottmann, Joerg; Dhou, Salam; Wagar, Matthew; Mannarino, Edward G; Mak, Raymond H; Lewis, John H

2015-01-01

Respiratory motion during radiotherapy can cause uncertainties in definition of the target volume and in estimation of the dose delivered to the target and healthy tissue. In this paper, we generate volumetric images of the internal patient anatomy during treatment using only the motion of a surrogate signal. Pre-treatment four-dimensional CT imaging is used to create a patient-specific model correlating internal respiratory motion with the trajectory of an external surrogate placed on the chest. The performance of this model is assessed with digital and physical phantoms reproducing measured irregular patient breathing patterns. Ten patient breathing patterns are incorporated in a digital phantom. For each patient breathing pattern, the model is used to generate images over the course of thirty seconds. The tumor position predicted by the model is compared to ground truth information from the digital phantom. Over the ten patient breathing patterns, the average absolute error in the tumor centroid position predicted by the motion model is 1.4 mm. The corresponding error for one patient breathing pattern implemented in an anthropomorphic physical phantom was 0.6 mm. The global voxel intensity error was used to compare the full image to the ground truth and demonstrates good agreement between predicted and true images. The model also generates accurate predictions for breathing patterns with irregular phases or amplitudes. (paper)

Generation of fluoroscopic 3D images with a respiratory motion model based on an external surrogate signal

Science.gov (United States)

Hurwitz, Martina; Williams, Christopher L.; Mishra, Pankaj; Rottmann, Joerg; Dhou, Salam; Wagar, Matthew; Mannarino, Edward G.; Mak, Raymond H.; Lewis, John H.

2015-01-01

Respiratory motion during radiotherapy can cause uncertainties in definition of the target volume and in estimation of the dose delivered to the target and healthy tissue. In this paper, we generate volumetric images of the internal patient anatomy during treatment using only the motion of a surrogate signal. Pre-treatment four-dimensional CT imaging is used to create a patient-specific model correlating internal respiratory motion with the trajectory of an external surrogate placed on the chest. The performance of this model is assessed with digital and physical phantoms reproducing measured irregular patient breathing patterns. Ten patient breathing patterns are incorporated in a digital phantom. For each patient breathing pattern, the model is used to generate images over the course of thirty seconds. The tumor position predicted by the model is compared to ground truth information from the digital phantom. Over the ten patient breathing patterns, the average absolute error in the tumor centroid position predicted by the motion model is 1.4 mm. The corresponding error for one patient breathing pattern implemented in an anthropomorphic physical phantom was 0.6 mm. The global voxel intensity error was used to compare the full image to the ground truth and demonstrates good agreement between predicted and true images. The model also generates accurate predictions for breathing patterns with irregular phases or amplitudes.

Application of a net-based baseline correction scheme to strong-motion records of the 2011 Mw 9.0 Tohoku earthquake

Science.gov (United States)

Tu, Rui; Wang, Rongjiang; Zhang, Yong; Walter, Thomas R.

2014-06-01

The description of static displacements associated with earthquakes is traditionally achieved using GPS, EDM or InSAR data. In addition, displacement histories can be derived from strong-motion records, allowing an improvement of geodetic networks at a high sampling rate and a better physical understanding of earthquake processes. Strong-motion records require a correction procedure appropriate for baseline shifts that may be caused by rotational motion, tilting and other instrumental effects. Common methods use an empirical bilinear correction on the velocity seismograms integrated from the strong-motion records. In this study, we overcome the weaknesses of an empirically based bilinear baseline correction scheme by using a net-based criterion to select the timing parameters. This idea is based on the physical principle that low-frequency seismic waveforms at neighbouring stations are coherent if the interstation distance is much smaller than the distance to the seismic source. For a dense strong-motion network, it is plausible to select the timing parameters so that the correlation coefficient between the velocity seismograms of two neighbouring stations is maximized after the baseline correction. We applied this new concept to the KiK-Net and K-Net strong-motion data available for the 2011 Mw 9.0 Tohoku earthquake. We compared the derived coseismic static displacement with high-quality GPS data, and with the results obtained using empirical methods. The results show that the proposed net-based approach is feasible and more robust than the individual empirical approaches. The outliers caused by unknown problems in the measurement system can be easily detected and quantified.

WE-D-303-02: Applications of Volumetric Images Generated with a Respiratory Motion Model Based On An External Surrogate Signal

International Nuclear Information System (INIS)

Hurwitz, M; Williams, C; Dhou, S; Lewis, J; Mishra, P

2015-01-01

Purpose: Respiratory motion can vary significantly over the course of simulation and treatment. Our goal is to use volumetric images generated with a respiratory motion model to improve the definition of the internal target volume (ITV) and the estimate of delivered dose. Methods: Ten irregular patient breathing patterns spanning 35 seconds each were incorporated into a digital phantom. Ten images over the first five seconds of breathing were used to emulate a 4DCT scan, build the ITV, and generate a patient-specific respiratory motion model which correlated the measured trajectories of markers placed on the patients’ chests with the motion of the internal anatomy. This model was used to generate volumetric images over the subsequent thirty seconds of breathing. The increase in the ITV taking into account the full 35 seconds of breathing was assessed with ground-truth and model-generated images. For one patient, a treatment plan based on the initial ITV was created and the delivered dose was estimated using images from the first five seconds as well as ground-truth and model-generated images from the next 30 seconds. Results: The increase in the ITV ranged from 0.2 cc to 6.9 cc for the ten patients based on ground-truth information. The model predicted this increase in the ITV with an average error of 0.8 cc. The delivered dose to the tumor (D95) changed significantly from 57 Gy to 41 Gy when estimated using 5 seconds and 30 seconds, respectively. The model captured this effect, giving an estimated D95 of 44 Gy. Conclusion: A respiratory motion model generating volumetric images of the internal patient anatomy could be useful in estimating the increase in the ITV due to irregular breathing during simulation and in assessing delivered dose during treatment. This project was supported, in part, through a Master Research Agreement with Varian Medical Systems, Inc. and Radiological Society of North America Research Scholar Grant #RSCH1206

SU-E-I-80: Quantification of Respiratory and Cardiac Motion Effect in SPECT Acquisitions Using Anthropomorphic Models: A Monte Carlo Simulation Study

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Papadimitroulas, P; Kostou, T; Kagadis, G [University of Patras, Rion, Ahaia (Greece); Loudos, G [Technological Educational Institute of Athens, Egaleo, Attika (Greece)

2015-06-15

Purpose: The purpose of the present study was to quantify, evaluate the impact of cardiac and respiratory motion on clinical nuclear imaging protocols. Common SPECT and scintigraphic scans are studied using Monte Carlo (MC) simulations, comparing the resulted images with and without motion. Methods: Realistic simulations were executed using the GATE toolkit and the XCAT anthropomorphic phantom as a reference model for human anatomy. Three different radiopharmaceuticals based on 99mTc were studied, namely 99mTc-MDP, 99mTc—N—DBODC and 99mTc—DTPA-aerosol for bone, myocardium and lung scanning respectively. The resolution of the phantom was set to 3.5 mm{sup 3}. The impact of the motion on spatial resolution was quantified using a sphere with 3.5 mm diameter and 10 separate time frames, in the ECAM modeled SPECT scanner. Finally, respiratory motion impact on resolution and imaging of lung lesions was investigated. The MLEM algorithm was used for data reconstruction, while the literature derived biodistributions of the pharmaceuticals were used as activity maps in the simulations. Results: FWHM was extracted for a static and a moving sphere which was ∼23 cm away from the entrance of the SPECT head. The difference in the FWHM was 20% between the two simulations. Profiles in thorax were compared in the case of bone scintigraphy, showing displacement and blurring of the bones when respiratory motion was inserted in the simulation. Large discrepancies were noticed in the case of myocardium imaging when cardiac motion was incorporated during the SPECT acquisition. Finally the borders of the lungs are blurred when respiratory motion is included resulting to a dislocation of ∼2.5 cm. Conclusion: As we move to individualized imaging and therapy procedures, quantitative and qualitative imaging is of high importance in nuclear diagnosis. MC simulations combined with anthropomorphic digital phantoms can provide an accurate tool for applications like motion correction

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

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

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

MO-FG-BRA-02: A Feasibility Study of Integrating Breathing Audio Signal with Surface Surrogates for Respiratory Motion Management

Energy Technology Data Exchange (ETDEWEB)

Lei, Y; Zhu, X; Zheng, D; Li, S; Ma, R; Zhang, M; Fan, Q; Wang, X; Verma, V; Zhou, S [University of Nebraska Medical Center, Omaha, NE (United States); Tang, X [Memorial Sloan Kettering Cancer Center, West Harrison, NY (United States)

2016-06-15

Purpose: Tracking the surrogate placed on patient skin surface sometimes leads to problematic signals for certain patients, such as shallow breathers. This in turn impairs the 4D CT image quality and dosimetric accuracy. In this pilot study, we explored the feasibility of monitoring human breathing motion by integrating breathing sound signal with surface surrogates. Methods: The breathing sound signals were acquired though a microphone attached adjacently to volunteer’s nostrils, and breathing curve were analyzed using a low pass filter. Simultaneously, the Real-time Position Management™ (RPM) system from Varian were employed on a volunteer to monitor respiratory motion including both shallow and deep breath modes. The similar experiment was performed by using Calypso system, and three beacons taped on volunteer abdominal region to capture breath motion. The period of each breathing curves were calculated with autocorrelation functions. The coherence and consistency between breathing signals using different acquisition methods were examined. Results: Clear breathing patterns were revealed by the sound signal which was coherent with the signal obtained from both the RPM system and Calypso system. For shallow breathing, the periods of breathing cycle were 3.00±0.19 sec (sound) and 3.00±0.21 sec (RPM); For deep breathing, the periods were 3.49± 0.11 sec (sound) and 3.49±0.12 sec (RPM). Compared with 4.54±0.66 sec period recorded by the calypso system, the sound measured 4.64±0.54 sec. The additional signal from sound could be supplement to the surface monitoring, and provide new parameters to model the hysteresis lung motion. Conclusion: Our preliminary study shows that the breathing sound signal can provide a comparable way as the RPM system to evaluate the respiratory motion. It’s instantaneous and robust characteristics facilitate it possibly to be a either independently or as auxiliary methods to manage respiratory motion in radiotherapy.

MO-FG-BRA-02: A Feasibility Study of Integrating Breathing Audio Signal with Surface Surrogates for Respiratory Motion Management

International Nuclear Information System (INIS)

Lei, Y; Zhu, X; Zheng, D; Li, S; Ma, R; Zhang, M; Fan, Q; Wang, X; Verma, V; Zhou, S; Tang, X

2016-01-01

Purpose: Tracking the surrogate placed on patient skin surface sometimes leads to problematic signals for certain patients, such as shallow breathers. This in turn impairs the 4D CT image quality and dosimetric accuracy. In this pilot study, we explored the feasibility of monitoring human breathing motion by integrating breathing sound signal with surface surrogates. Methods: The breathing sound signals were acquired though a microphone attached adjacently to volunteer’s nostrils, and breathing curve were analyzed using a low pass filter. Simultaneously, the Real-time Position Management™ (RPM) system from Varian were employed on a volunteer to monitor respiratory motion including both shallow and deep breath modes. The similar experiment was performed by using Calypso system, and three beacons taped on volunteer abdominal region to capture breath motion. The period of each breathing curves were calculated with autocorrelation functions. The coherence and consistency between breathing signals using different acquisition methods were examined. Results: Clear breathing patterns were revealed by the sound signal which was coherent with the signal obtained from both the RPM system and Calypso system. For shallow breathing, the periods of breathing cycle were 3.00±0.19 sec (sound) and 3.00±0.21 sec (RPM); For deep breathing, the periods were 3.49± 0.11 sec (sound) and 3.49±0.12 sec (RPM). Compared with 4.54±0.66 sec period recorded by the calypso system, the sound measured 4.64±0.54 sec. The additional signal from sound could be supplement to the surface monitoring, and provide new parameters to model the hysteresis lung motion. Conclusion: Our preliminary study shows that the breathing sound signal can provide a comparable way as the RPM system to evaluate the respiratory motion. It’s instantaneous and robust characteristics facilitate it possibly to be a either independently or as auxiliary methods to manage respiratory motion in radiotherapy.

Surrogate-driven deformable motion model for organ motion tracking in particle radiation therapy

Science.gov (United States)

Fassi, Aurora; Seregni, Matteo; Riboldi, Marco; Cerveri, Pietro; Sarrut, David; Battista Ivaldi, Giovanni; Tabarelli de Fatis, Paola; Liotta, Marco; Baroni, Guido

2015-02-01

The aim of this study is the development and experimental testing of a tumor tracking method for particle radiation therapy, providing the daily respiratory dynamics of the patient’s thoraco-abdominal anatomy as a function of an external surface surrogate combined with an a priori motion model. The proposed tracking approach is based on a patient-specific breathing motion model, estimated from the four-dimensional (4D) planning computed tomography (CT) through deformable image registration. The model is adapted to the interfraction baseline variations in the patient’s anatomical configuration. The driving amplitude and phase parameters are obtained intrafractionally from a respiratory surrogate signal derived from the external surface displacement. The developed technique was assessed on a dataset of seven lung cancer patients, who underwent two repeated 4D CT scans. The first 4D CT was used to build the respiratory motion model, which was tested on the second scan. The geometric accuracy in localizing lung lesions, mediated over all breathing phases, ranged between 0.6 and 1.7 mm across all patients. Errors in tracking the surrounding organs at risk, such as lungs, trachea and esophagus, were lower than 1.3 mm on average. The median absolute variation in water equivalent path length (WEL) within the target volume did not exceed 1.9 mm-WEL for simulated particle beams. A significant improvement was achieved compared with error compensation based on standard rigid alignment. The present work can be regarded as a feasibility study for the potential extension of tumor tracking techniques in particle treatments. Differently from current tracking methods applied in conventional radiotherapy, the proposed approach allows for the dynamic localization of all anatomical structures scanned in the planning CT, thus providing complete information on density and WEL variations required for particle beam range adaptation.

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.

Evaluating correlation between geometrical relationship and dose difference caused by respiratory motion using statistical analysis

Energy Technology Data Exchange (ETDEWEB)

Shin, Dong Seok; Kim, Dong Su; Kim, Tae Ho; Kim, Kyeong Hyeon; Yoon, Do Kun; Suh, Tae Suk [The Catholic University of Korea, Seoul (Korea, Republic of); Kang, Seong Hee [Seoul National University Hospital, Seoul (Korea, Republic of); Cho, Min Seok [Asan Medical Center, Seoul (Korea, Republic of); Noh, Yu Yoon [Eulji University Hospital, Daejeon (Korea, Republic of)

2017-04-15

Three-dimensional dose (3D dose) can consider coverage of moving target, however it is difficult to provide dosimetric effect which occurs by respiratory motions. Four-dimensional dose (4D dose) which uses deformable image registration (DIR) algorithm from four-dimensional computed tomography (4DCT) images can consider dosimetric effect by respiratory motions. The dose difference between 3D dose and 4D dose can be varied according to the geometrical relationship between a planning target volume (PTV) and an organ at risk (OAR). The purpose of this study is to evaluate the correlation between the overlap volume histogram (OVH), which quantitatively shows the geometrical relationship between the PTV and OAR, and the dose differences. In conclusion, no significant statistical correlation was found between the OVH and dose differences. However, it was confirmed that a higher difference between the 3D and 4D doses could occur in cases that have smaller OVH value. No significant statistical correlation was found between the OVH and dose differences. However, it was confirmed that a higher difference between the 3D and 4D doses could occur in cases that have smaller OVH value.

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.

4D-CT scans reveal reduced magnitude of respiratory liver motion achieved by different abdominal compression plate positions in patients with intrahepatic tumors undergoing helical tomotherapy

Energy Technology Data Exchange (ETDEWEB)

Hu, Yong, E-mail: hu.yong@zs-hospital.sh.cn; Zhou, Yong-Kang, E-mail: zhouyk2009@163.com; Chen, Yi-Xing, E-mail: chen.yixing@zs-hospital.sh.cn; Shi, Shi-Ming, E-mail: shiming32@126.com; Zeng, Zhao-Chong, E-mail: zeng.zhaochong@zs-hospital.sh.cn [Department of Radiation Oncology, Zhongshan Hospital, Fudan University, 180 Feng Lin Road, Shanghai 200032 (China)

2016-07-15

Purpose: While abdominal compression (AC) can be used to reduce respiratory liver motion in patients receiving helical tomotherapy for hepatocellular carcinoma, the nature and extent of this effect is not well described. The purpose of this study was to evaluate the changes in magnitude of three-dimensional liver motion with abdominal compression using four-dimensional (4D) computed tomography (CT) images of several plate positions. Methods: From January 2012 to October 2015, 72 patients with intrahepatic carcinoma and divided into four groups underwent 4D-CT scans to assess respiratory liver motion. Of the 72 patients, 19 underwent abdominal compression of the cephalic area between the subxiphoid and umbilicus (group A), 16 underwent abdominal compression of the caudal region between the subxiphoid area and the umbilicus (group B), 11 patients underwent abdominal compression of the caudal umbilicus (group C), and 26 patients remained free breathing (group D). 4D-CT images were sorted into ten-image series, according to the respiratory phase from the end inspiration to the end expiration, and then transferred to treatment planning software. All liver contours were drawn by a single physician and confirmed by a second physician. Liver relative coordinates were automatically generated to calculate the liver respiratory motion in different axial directions to compile the 10 ten contours into a single composite image. Differences in respiratory liver motion were assessed with a one-way analysis of variance test of significance. Results: The average respiratory liver motion in the Y axial direction was 4.53 ± 1.16, 7.56 ± 1.30, 9.95 ± 2.32, and 9.53 ± 2.62 mm in groups A, B, C, and D, respectively, with a significant change among the four groups (p < 0.001). Abdominal compression was most effective in group A (compression plate on the subxiphoid area), with liver displacement being 2.53 ± 0.93, 4.53 ± 1.16, and 2.14 ± 0.92 mm on the X-, Y-, and Z

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.

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 05: A novel respiratory motion simulation program for VMAT treatment plans: a phantom validation study

Energy Technology Data Exchange (ETDEWEB)

Hubley, Emily; Pierce, Greg; Ploquin, Nicolas [University of Calgary, Tom Baker Cancer Centre, Tom Baker Cancer Centre (Canada)

2016-08-15

Purpose: To develop and validate a computational method to simulate craniocaudal respiratory motion in a VMAT treatment plan. Methods: Three 4DCTs of the QUASAR respiratory motion phantom were acquired with a 2cm water-density spherical tumour embedded in cedar to simulate lung. The phantom was oscillating sinusoidally with an amplitude of 2cm and periods of 3, 4, and 5 seconds. An ITV was contoured and 5mm PTV margin was added. High and a low modulation factor VMAT plans were created for each scan. An in-house program was developed to simulate respiratory motion in the treatment plans by shifting the MLC leaf positions relative to the phantom. Each plan was delivered to the phantom and the dose was measured using Gafchromic film. The measured and calculated plans were compared using an absolute dose gamma analysis (3%/3mm). Results: The average gamma pass rate for the low modulation plan and high modulation plans were 91.1% and 51.4% respectively. The difference between the high and low modulation plans gamma pass rates is likely related to the different sampling frequency of the respiratory curve and the higher MLC leaf speeds in the high modulation plan. A high modulation plan has a slower gantry speed and therefore samples the breathing cycle at a coarser frequency leading to inaccuracies between the measured and planned doses. Conclusion: A simple program, including a novel method for increasing sampling frequency beyond the control point frequency, has been developed to simulate respiratory motion in VMAT plans by shifting the MLC leaf positions.

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 05: A novel respiratory motion simulation program for VMAT treatment plans: a phantom validation study

International Nuclear Information System (INIS)

Hubley, Emily; Pierce, Greg; Ploquin, Nicolas

2016-01-01

Purpose: To develop and validate a computational method to simulate craniocaudal respiratory motion in a VMAT treatment plan. Methods: Three 4DCTs of the QUASAR respiratory motion phantom were acquired with a 2cm water-density spherical tumour embedded in cedar to simulate lung. The phantom was oscillating sinusoidally with an amplitude of 2cm and periods of 3, 4, and 5 seconds. An ITV was contoured and 5mm PTV margin was added. High and a low modulation factor VMAT plans were created for each scan. An in-house program was developed to simulate respiratory motion in the treatment plans by shifting the MLC leaf positions relative to the phantom. Each plan was delivered to the phantom and the dose was measured using Gafchromic film. The measured and calculated plans were compared using an absolute dose gamma analysis (3%/3mm). Results: The average gamma pass rate for the low modulation plan and high modulation plans were 91.1% and 51.4% respectively. The difference between the high and low modulation plans gamma pass rates is likely related to the different sampling frequency of the respiratory curve and the higher MLC leaf speeds in the high modulation plan. A high modulation plan has a slower gantry speed and therefore samples the breathing cycle at a coarser frequency leading to inaccuracies between the measured and planned doses. Conclusion: A simple program, including a novel method for increasing sampling frequency beyond the control point frequency, has been developed to simulate respiratory motion in VMAT plans by shifting the MLC leaf positions.

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.

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

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.

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.

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

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

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

When is respiratory management necessary for partial breast intensity modulated radiotherapy: A respiratory amplitude escalation treatment planning study

International Nuclear Information System (INIS)

Quirk, Sarah; Conroy, Leigh; Smith, Wendy L.

2014-01-01

Purpose: The impact of typical respiratory motion amplitudes (∼2 mm) on partial breast irradiation (PBI) is minimal; however, some patients have larger respiratory amplitudes that may negatively affect dose homogeneity. Here we determine at what amplitude respiratory management may be required to maintain plan quality. Methods and Materials: Ten patients were planned with PBI IMRT. Respiratory motion (2–20 mm amplitude) probability density functions were convolved with static plan fluence to estimate the delivered dose. Evaluation metrics included target coverage, ipsilateral breast hotspot, homogeneity, and uniformity indices. Results: Degradation of dose homogeneity was the limiting factor in reduction of plan quality due to respiratory motion, not loss of coverage. Hotspot increases were observed even at typical motion amplitudes. At 2 and 5 mm, 2/10 plans had a hotspot greater than 107% and at 10 mm this increased to 5/10 plans. Target coverage was only compromised at larger amplitudes: 5/10 plans did not meet coverage criteria at 15 mm amplitude and no plans met minimum coverage at 20 mm. Conclusions: We recommend that if respiratory amplitude is greater than 10 mm, respiratory management or alternative radiotherapy should be considered due to an increase in the hotspot in the ipsilateral breast and a decrease in dose homogeneity

Respiratory impact on motion sickness induced by linear motion

NARCIS (Netherlands)

Mert, A.; Klöpping-Ketelaars, I.; Bles, W.

2009-01-01

Motion sickness incidence (MSI) for vertical sinusoidal motion reaches a maximum at 0.167 Hz. Normal breathing frequency is close to this frequency. There is some evidence for synchronization of breathing with this stimulus frequency. If this enforced breathing takes place over a larger frequency

A multiple model approach to respiratory motion prediction for real-time IGRT

International Nuclear Information System (INIS)

Putra, Devi; Haas, Olivier C L; Burnham, Keith J; Mills, John A

2008-01-01

Respiration induces significant movement of tumours in the vicinity of thoracic and abdominal structures. Real-time image-guided radiotherapy (IGRT) aims to adapt radiation delivery to tumour motion during irradiation. One of the main problems for achieving this objective is the presence of time lag between the acquisition of tumour position and the radiation delivery. Such time lag causes significant beam positioning errors and affects the dose coverage. A method to solve this problem is to employ an algorithm that is able to predict future tumour positions from available tumour position measurements. This paper presents a multiple model approach to respiratory-induced tumour motion prediction using the interacting multiple model (IMM) filter. A combination of two models, constant velocity (CV) and constant acceleration (CA), is used to capture respiratory-induced tumour motion. A Kalman filter is designed for each of the local models and the IMM filter is applied to combine the predictions of these Kalman filters for obtaining the predicted tumour position. The IMM filter, likewise the Kalman filter, is a recursive algorithm that is suitable for real-time applications. In addition, this paper proposes a confidence interval (CI) criterion to evaluate the performance of tumour motion prediction algorithms for IGRT. The proposed CI criterion provides a relevant measure for the prediction performance in terms of clinical applications and can be used to specify the margin to accommodate prediction errors. The prediction performance of the IMM filter has been evaluated using 110 traces of 4-minute free-breathing motion collected from 24 lung-cancer patients. The simulation study was carried out for prediction time 0.1-0.6 s with sampling rates 3, 5 and 10 Hz. It was found that the prediction of the IMM filter was consistently better than the prediction of the Kalman filter with the CV or CA model. There was no significant difference of prediction errors for the

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

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

The application of a low-cost 3D depth camera for patient set-up and respiratory motion management in radiotherapy

Science.gov (United States)

Tahavori, Fatemeh

Respiratory motion induces uncertainty in External Beam Radiotherapy (EBRT), which can result in sub-optimal dose delivery to the target tissue and unwanted dose to normal tissue. The conventional approach to managing patient respiratory motion for EBRT within the area of abdominal-thoracic cancer is through the use of internal radiological imaging methods (e.g. Megavoltage imaging or Cone-Beam Computed Tomography) or via surrogate estimates of tumour position using external markers placed on the patient chest. This latter method uses tracking with video-based techniques, and relies on an assumed correlation or mathematical model, between the external surrogate signal and the internal target position. The marker's trajectory can be used in both respiratory gating techniques and real-time tracking methods. Internal radiological imaging methods bring with them limited temporal resolution, and additional radiation burden, which can be addressed by external marker-based methods that carry no such issues. Moreover, by including multiple external markers and placing them closer to the internal target organs, the effciency of correlation algorithms can be increased. However, the quality of such external monitoring methods is underpinned by the performance of the associated correlation model. Therefore, several new approaches to correlation modelling have been developed as part of this thesis and compared using publicly-available datasets. Highly competitive results have been obtained when compared against state-of-the-art methods. Marker-based methods also have the disadvantages of requiring manual set-up time for marker placement and patient positioning and potential issues with reproducibility of marker placement. This motivates the investigation of non-contact marker-free methods for use in EBRT, which is the main topic of this thesis. The Microsoft Kinect is used as an example of a low-cost consumer grade 3D depth camera for capturing and analysing external

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.

TU-F-17A-03: An Analytical Respiratory Perturbation Model for Lung Motion Prediction

International Nuclear Information System (INIS)

Li, G; Yuan, A; Wei, J

2014-01-01

Purpose: Breathing irregularity is common, causing unreliable prediction in tumor motion for correlation-based surrogates. Both tidal volume (TV) and breathing pattern (BP=ΔVthorax/TV, where TV=ΔVthorax+ΔVabdomen) affect lung motion in anterior-posterior and superior-inferior directions. We developed a novel respiratory motion perturbation (RMP) model in analytical form to account for changes in TV and BP in motion prediction from simulation to treatment. Methods: The RMP model is an analytical function of patient-specific anatomic and physiologic parameters. It contains a base-motion trajectory d(x,y,z) derived from a 4-dimensional computed tomography (4DCT) at simulation and a perturbation term Δd(ΔTV,ΔBP) accounting for deviation at treatment from simulation. The perturbation is dependent on tumor-specific location and patient-specific anatomy. Eleven patients with simulation and treatment 4DCT images were used to assess the RMP method in motion prediction from 4DCT1 to 4DCT2, and vice versa. For each patient, ten motion trajectories of corresponding points in the lower lobes were measured in both 4DCTs: one served as the base-motion trajectory and the other as the ground truth for comparison. In total, 220 motion trajectory predictions were assessed. The motion discrepancy between two 4DCTs for each patient served as a control. An established 5D motion model was used for comparison. Results: The average absolute error of RMP model prediction in superior-inferior direction is 1.6±1.8 mm, similar to 1.7±1.6 mm from the 5D model (p=0.98). Some uncertainty is associated with limited spatial resolution (2.5mm slice thickness) and temporal resolution (10-phases). Non-corrected motion discrepancy between two 4DCTs is 2.6±2.7mm, with the maximum of ±20mm, and correction is necessary (p=0.01). Conclusion: The analytical motion model predicts lung motion with accuracy similar to the 5D model. The analytical model is based on physical relationships, requires no

Incidence of Changes in Respiration-Induced Tumor Motion and Its Relationship With Respiratory Surrogates During Individual Treatment Fractions

International Nuclear Information System (INIS)

Malinowski, Kathleen; McAvoy, Thomas J.; George, Rohini; Dietrich, Sonja; D’Souza, Warren D.

2012-01-01

Purpose: To determine how frequently (1) tumor motion and (2) the spatial relationship between tumor and respiratory surrogate markers change during a treatment fraction in lung and pancreas cancer patients. Methods and Materials: A Cyberknife Synchrony system radiographically localized the tumor and simultaneously tracked three respiratory surrogate markers fixed to a form-fitting vest. Data in 55 lung and 29 pancreas fractions were divided into successive 10-min blocks. Mean tumor positions and tumor position distributions were compared across 10-min blocks of data. Treatment margins were calculated from both 10 and 30 min of data. Partial least squares (PLS) regression models of tumor positions as a function of external surrogate marker positions were created from the first 10 min of data in each fraction; the incidence of significant PLS model degradation was used to assess changes in the spatial relationship between tumors and surrogate markers. Results: The absolute change in mean tumor position from first to third 10-min blocks was >5 mm in 13% and 7% of lung and pancreas cases, respectively. Superior–inferior and medial–lateral differences in mean tumor position were significantly associated with the lobe of lung. In 61% and 54% of lung and pancreas fractions, respectively, margins calculated from 30 min of data were larger than margins calculated from 10 min of data. The change in treatment margin magnitude for superior–inferior motion was >1 mm in 42% of lung and 45% of pancreas fractions. Significantly increasing tumor position prediction model error (mean ± standard deviation rates of change of 1.6 ± 2.5 mm per 10 min) over 30 min indicated tumor–surrogate relationship changes in 63% of fractions. Conclusions: Both tumor motion and the relationship between tumor and respiratory surrogate displacements change in most treatment fractions for patient in-room time of 30 min.

Incidence of Changes in Respiration-Induced Tumor Motion and Its Relationship With Respiratory Surrogates During Individual Treatment Fractions

Energy Technology Data Exchange (ETDEWEB)

Malinowski, Kathleen [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); McAvoy, Thomas J. [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Institute of Systems Research, University of Maryland, College Park, MD (United States); George, Rohini [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Dietrich, Sonja [Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, CA (United States); D' Souza, Warren D., E-mail: wdsou001@umaryland.edu [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States)

2012-04-01

Purpose: To determine how frequently (1) tumor motion and (2) the spatial relationship between tumor and respiratory surrogate markers change during a treatment fraction in lung and pancreas cancer patients. Methods and Materials: A Cyberknife Synchrony system radiographically localized the tumor and simultaneously tracked three respiratory surrogate markers fixed to a form-fitting vest. Data in 55 lung and 29 pancreas fractions were divided into successive 10-min blocks. Mean tumor positions and tumor position distributions were compared across 10-min blocks of data. Treatment margins were calculated from both 10 and 30 min of data. Partial least squares (PLS) regression models of tumor positions as a function of external surrogate marker positions were created from the first 10 min of data in each fraction; the incidence of significant PLS model degradation was used to assess changes in the spatial relationship between tumors and surrogate markers. Results: The absolute change in mean tumor position from first to third 10-min blocks was >5 mm in 13% and 7% of lung and pancreas cases, respectively. Superior-inferior and medial-lateral differences in mean tumor position were significantly associated with the lobe of lung. In 61% and 54% of lung and pancreas fractions, respectively, margins calculated from 30 min of data were larger than margins calculated from 10 min of data. The change in treatment margin magnitude for superior-inferior motion was >1 mm in 42% of lung and 45% of pancreas fractions. Significantly increasing tumor position prediction model error (mean {+-} standard deviation rates of change of 1.6 {+-} 2.5 mm per 10 min) over 30 min indicated tumor-surrogate relationship changes in 63% of fractions. Conclusions: Both tumor motion and the relationship between tumor and respiratory surrogate displacements change in most treatment fractions for patient in-room time of 30 min.

Radiotherapy of tumors under respiratory motion. Estimation of the motional velocity field and dose accumulation based on 4D image data; Strahlentherapie atmungsbewegter Tumoren. Bewegungsfeldschaetzung und Dosisakkumulation anhand von 4D-Bilddaten

Energy Technology Data Exchange (ETDEWEB)

Werner, Rene

2013-07-01

Respiratory motion represents a major challenge in radiation therapy in general, and especially for the therapy of lung tumors. In recent years and due to the introduction of modern techniques to 'acquire temporally resolved computed tomography images (4D CT images), different approaches have been developed to explicitly account for breathing motion during treatment. An integral component of such approaches is the concept of motion field estimation, which aims at a mathematical description and the computation of the motion sequences represented by the patient's images. As part of a 4D dose calculation/dose accumulation, the resulting vector fields are applied for assessing and accounting for breathing-induced effects on the dose distribution to be delivered. The reliability of related 4D treatment planning concepts is therefore directly tailored to the precision of the underlying motion field estimation process. Taking this into account, the thesis aims at developing optimized methods for the estimation of motion fields using 4D CT images and applying the resulting methods for the analysis of breathing induced dosimetric effects in radiation therapy. The thesis is subdivided into three parts that thematically build upon each other. The first part of the thesis is about the implementation, evaluation and optimization of methods for motion field estimation with the goal of precisely assessing respiratory motion of anatomical and pathological structures represented in a patient's 4D er image sequence; this step is the basis of subsequent developments and analysis parts. Especially non-linear registration techniques prove to be well suited to this purpose. After being optimized for the particular problem at hand, it is shown as part of an extensive multi-criteria evaluation study and additionally taking into account publicly accessible evaluation platforms that such methods allow estimating motion fields with subvoxel accuracy - which means that the

Reference respiratory waveforms by minimum jerk model analysis

Energy Technology Data Exchange (ETDEWEB)

Anetai, Yusuke, E-mail: anetai@radonc.med.osaka-u.ac.jp; Sumida, Iori; Takahashi, Yutaka; Yagi, Masashi; Mizuno, Hirokazu; Ogawa, Kazuhiko [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita-shi, Osaka 565-0871 (Japan); Ota, Seiichi [Department of Medical Technology, Osaka University Hospital, Yamadaoka 2-15, Suita-shi, Osaka 565-0871 (Japan)

2015-09-15

Purpose: CyberKnife{sup ®} robotic surgery system has the ability to deliver radiation to a tumor subject to respiratory movements using Synchrony{sup ®} mode with less than 2 mm tracking accuracy. However, rapid and rough motion tracking causes mechanical tracking errors and puts mechanical stress on the robotic joint, leading to unexpected radiation delivery errors. During clinical treatment, patient respiratory motions are much more complicated, suggesting the need for patient-specific modeling of respiratory motion. The purpose of this study was to propose a novel method that provides a reference respiratory wave to enable smooth tracking for each patient. Methods: The minimum jerk model, which mathematically derives smoothness by means of jerk, or the third derivative of position and the derivative of acceleration with respect to time that is proportional to the time rate of force changed was introduced to model a patient-specific respiratory motion wave to provide smooth motion tracking using CyberKnife{sup ®}. To verify that patient-specific minimum jerk respiratory waves were being tracked smoothly by Synchrony{sup ®} mode, a tracking laser projection from CyberKnife{sup ®} was optically analyzed every 0.1 s using a webcam and a calibrated grid on a motion phantom whose motion was in accordance with three pattern waves (cosine, typical free-breathing, and minimum jerk theoretical wave models) for the clinically relevant superior–inferior directions from six volunteers assessed on the same node of the same isocentric plan. Results: Tracking discrepancy from the center of the grid to the beam projection was evaluated. The minimum jerk theoretical wave reduced the maximum-peak amplitude of radial tracking discrepancy compared with that of the waveforms modeled by cosine and typical free-breathing model by 22% and 35%, respectively, and provided smooth tracking for radial direction. Motion tracking constancy as indicated by radial tracking discrepancy

Reference respiratory waveforms by minimum jerk model analysis

International Nuclear Information System (INIS)

Anetai, Yusuke; Sumida, Iori; Takahashi, Yutaka; Yagi, Masashi; Mizuno, Hirokazu; Ogawa, Kazuhiko; Ota, Seiichi

2015-01-01

Purpose: CyberKnife"® robotic surgery system has the ability to deliver radiation to a tumor subject to respiratory movements using Synchrony"® mode with less than 2 mm tracking accuracy. However, rapid and rough motion tracking causes mechanical tracking errors and puts mechanical stress on the robotic joint, leading to unexpected radiation delivery errors. During clinical treatment, patient respiratory motions are much more complicated, suggesting the need for patient-specific modeling of respiratory motion. The purpose of this study was to propose a novel method that provides a reference respiratory wave to enable smooth tracking for each patient. Methods: The minimum jerk model, which mathematically derives smoothness by means of jerk, or the third derivative of position and the derivative of acceleration with respect to time that is proportional to the time rate of force changed was introduced to model a patient-specific respiratory motion wave to provide smooth motion tracking using CyberKnife"®. To verify that patient-specific minimum jerk respiratory waves were being tracked smoothly by Synchrony"® mode, a tracking laser projection from CyberKnife"® was optically analyzed every 0.1 s using a webcam and a calibrated grid on a motion phantom whose motion was in accordance with three pattern waves (cosine, typical free-breathing, and minimum jerk theoretical wave models) for the clinically relevant superior–inferior directions from six volunteers assessed on the same node of the same isocentric plan. Results: Tracking discrepancy from the center of the grid to the beam projection was evaluated. The minimum jerk theoretical wave reduced the maximum-peak amplitude of radial tracking discrepancy compared with that of the waveforms modeled by cosine and typical free-breathing model by 22% and 35%, respectively, and provided smooth tracking for radial direction. Motion tracking constancy as indicated by radial tracking discrepancy affected by respiratory

TH-CD-207A-03: A Surface Deformation Driven Respiratory Model for Organ Motion Tracking in Lung Cancer Radiotherapy

International Nuclear Information System (INIS)

Chen, H; Zhen, X; Zhou, L; Gu, X

2016-01-01

Purpose: To propose and validate a novel real-time surface-mesh-based internal organ-external surface motion and deformation tracking method for lung cancer radiotherapy. Methods: Deformation vector fields (DVFs) which characterizes the internal and external motion are obtained by registering the internal organ and tumor contours and external surface meshes to a reference phase in the 4D CT images using a recent developed local topology preserved non-rigid point matching algorithm (TOP). A composite matrix is constructed by combing the estimated internal and external DVFs. Principle component analysis (PCA) is then applied on the composite matrix to extract principal motion characteristics and finally yield the respiratory motion model parameters which correlates the internal and external motion and deformation. The accuracy of the respiratory motion model is evaluated using a 4D NURBS-based cardiac-torso (NCAT) synthetic phantom and three lung cancer cases. The center of mass (COM) difference is used to measure the tumor motion tracking accuracy, and the Dice’s coefficient (DC), percent error (PE) and Housdourf’s distance (HD) are used to measure the agreement between the predicted and ground truth tumor shape. Results: The mean COM is 0.84±0.49mm and 0.50±0.47mm for the phantom and patient data respectively. The mean DC, PE and HD are 0.93±0.01, 0.13±0.03 and 1.24±0.34 voxels for the phantom, and 0.91±0.04, 0.17±0.07 and 3.93±2.12 voxels for the three lung cancer patients, respectively. Conclusions: We have proposed and validate a real-time surface-mesh-based organ motion and deformation tracking method with an internal-external motion modeling. The preliminary results conducted on a synthetic 4D NCAT phantom and 4D CT images from three lung cancer cases show that the proposed method is reliable and accurate in tracking both the tumor motion trajectory and deformation, which can serve as a potential tool for real-time organ motion and deformation

TH-CD-207A-03: A Surface Deformation Driven Respiratory Model for Organ Motion Tracking in Lung Cancer Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Chen, H; Zhen, X; Zhou, L [Southern Medical University, Guangzhou, Guangdong (China); Gu, X [UT Southwestern Medical Center, Dallas, TX (United States)

2016-06-15

Purpose: To propose and validate a novel real-time surface-mesh-based internal organ-external surface motion and deformation tracking method for lung cancer radiotherapy. Methods: Deformation vector fields (DVFs) which characterizes the internal and external motion are obtained by registering the internal organ and tumor contours and external surface meshes to a reference phase in the 4D CT images using a recent developed local topology preserved non-rigid point matching algorithm (TOP). A composite matrix is constructed by combing the estimated internal and external DVFs. Principle component analysis (PCA) is then applied on the composite matrix to extract principal motion characteristics and finally yield the respiratory motion model parameters which correlates the internal and external motion and deformation. The accuracy of the respiratory motion model is evaluated using a 4D NURBS-based cardiac-torso (NCAT) synthetic phantom and three lung cancer cases. The center of mass (COM) difference is used to measure the tumor motion tracking accuracy, and the Dice’s coefficient (DC), percent error (PE) and Housdourf’s distance (HD) are used to measure the agreement between the predicted and ground truth tumor shape. Results: The mean COM is 0.84±0.49mm and 0.50±0.47mm for the phantom and patient data respectively. The mean DC, PE and HD are 0.93±0.01, 0.13±0.03 and 1.24±0.34 voxels for the phantom, and 0.91±0.04, 0.17±0.07 and 3.93±2.12 voxels for the three lung cancer patients, respectively. Conclusions: We have proposed and validate a real-time surface-mesh-based organ motion and deformation tracking method with an internal-external motion modeling. The preliminary results conducted on a synthetic 4D NCAT phantom and 4D CT images from three lung cancer cases show that the proposed method is reliable and accurate in tracking both the tumor motion trajectory and deformation, which can serve as a potential tool for real-time organ motion and deformation

Respiratory motion tracking using Microsoft’s Kinect v2 camera

Directory of Open Access Journals (Sweden)

Ernst Floris

2015-09-01

Full Text Available In image-guided radiotherapy, monitoring and compensating for respiratory motion is of high importance. We have analysed the possibility to use Microsoft’s Kinect v2 sensor as a low-cost tracking camera. In our experiment, eleven circular markers were printed onto a Lycra shirt and were tracked in the camera’s color image using cross correlation-based template matching. The 3D position of the marker was determined using this information and the mean distance of all template pixels from the sensor. In an experiment with four volunteers (male and female we could demonstrate that real time position tracking is possible in 3D. By averaging over the depth values inside the template, it was possible to increase the Kinect’s depth resolution from 1 mm to 0.1 mm. The noise level was reduced to a standard deviation of 0.4 mm. Temperature sensitivity of the measured depth values was observed for about 10-15 minutes after system start.

TH-CD-207A-07: Prediction of High Dimensional State Subject to Respiratory Motion: A Manifold Learning Approach

International Nuclear Information System (INIS)

Liu, W; Sawant, A; Ruan, D

2016-01-01

Purpose: The development of high dimensional imaging systems (e.g. volumetric MRI, CBCT, photogrammetry systems) in image-guided radiotherapy provides important pathways to the ultimate goal of real-time volumetric/surface motion monitoring. This study aims to develop a prediction method for the high dimensional state subject to respiratory motion. Compared to conventional linear dimension reduction based approaches, our method utilizes manifold learning to construct a descriptive feature submanifold, where more efficient and accurate prediction can be performed. Methods: We developed a prediction framework for high-dimensional state subject to respiratory motion. The proposed method performs dimension reduction in a nonlinear setting to permit more descriptive features compared to its linear counterparts (e.g., classic PCA). Specifically, a kernel PCA is used to construct a proper low-dimensional feature manifold, where low-dimensional prediction is performed. A fixed-point iterative pre-image estimation method is applied subsequently to recover the predicted value in the original state space. We evaluated and compared the proposed method with PCA-based method on 200 level-set surfaces reconstructed from surface point clouds captured by the VisionRT system. The prediction accuracy was evaluated with respect to root-mean-squared-error (RMSE) for both 200ms and 600ms lookahead lengths. Results: The proposed method outperformed PCA-based approach with statistically higher prediction accuracy. In one-dimensional feature subspace, our method achieved mean prediction accuracy of 0.86mm and 0.89mm for 200ms and 600ms lookahead lengths respectively, compared to 0.95mm and 1.04mm from PCA-based method. The paired t-tests further demonstrated the statistical significance of the superiority of our method, with p-values of 6.33e-3 and 5.78e-5, respectively. Conclusion: The proposed approach benefits from the descriptiveness of a nonlinear manifold and the prediction

Experimental investigation of irregular motion impact on 4D PET-based particle therapy monitoring

International Nuclear Information System (INIS)

Tian, Y; Stützer, K; Enghardt, W; Priegnitz, M; Helmbrecht, S; Fiedler, F; Bert, C

2016-01-01

Particle therapy positron emission tomography (PT-PET) is an in vivo and non-invasive imaging technique to monitor treatment delivery in particle therapy. The inevitable patient respiratory motion during irradiation causes artefacts and inaccurate activity distribution in PET images. Four-dimensional (4D) maximum likelihood expectation maximisation (4D MLEM) allows for a compensation of these effects, but has up to now been restricted to regular motion for PT-PET investigations. However, intra-fractional motion during treatment might differ from that during acquisition of the 4D-planning CT (e.g. amplitude variation, baseline drift) and therefore might induce inaccurate 4D PET reconstruction results. This study investigates the impact of different irregular analytical one-dimensional (1D) motion patterns on PT-PET imaging by means of experiments with a radioactive source and irradiated moving phantoms. Three sorting methods, namely phase sorting, equal amplitude sorting and event-based amplitude sorting, were applied to manage the PET list-mode data. The influence of these sorting methods on the motion compensating algorithm has been analysed. The event-based amplitude sorting showed a superior performance and it is applicable for irregular motions with  ⩽4 mm amplitude elongation and drift. For motion with 10 mm baseline drift, the normalised root mean square error was as high as 10.5% and a 10 mm range deviation was observed. (note)

Experimental investigation of irregular motion impact on 4D PET-based particle therapy monitoring

Science.gov (United States)

Tian, Y.; Stützer, K.; Enghardt, W.; Priegnitz, M.; Helmbrecht, S.; Bert, C.; Fiedler, F.

2016-01-01

Particle therapy positron emission tomography (PT-PET) is an in vivo and non-invasive imaging technique to monitor treatment delivery in particle therapy. The inevitable patient respiratory motion during irradiation causes artefacts and inaccurate activity distribution in PET images. Four-dimensional (4D) maximum likelihood expectation maximisation (4D MLEM) allows for a compensation of these effects, but has up to now been restricted to regular motion for PT-PET investigations. However, intra-fractional motion during treatment might differ from that during acquisition of the 4D-planning CT (e.g. amplitude variation, baseline drift) and therefore might induce inaccurate 4D PET reconstruction results. This study investigates the impact of different irregular analytical one-dimensional (1D) motion patterns on PT-PET imaging by means of experiments with a radioactive source and irradiated moving phantoms. Three sorting methods, namely phase sorting, equal amplitude sorting and event-based amplitude sorting, were applied to manage the PET list-mode data. The influence of these sorting methods on the motion compensating algorithm has been analysed. The event-based amplitude sorting showed a superior performance and it is applicable for irregular motions with  ⩽4 mm amplitude elongation and drift. For motion with 10 mm baseline drift, the normalised root mean square error was as high as 10.5% and a 10 mm range deviation was observed.

Motion compensated digital tomosynthesis

NARCIS (Netherlands)

van der Reijden, Anneke; van Herk, Marcel; Sonke, Jan-Jakob

2013-01-01

Digital tomosynthesis (DTS) is a limited angle image reconstruction method for cone beam projections that offers patient surveillance capabilities during VMAT based SBRT delivery. Motion compensation (MC) has the potential to mitigate motion artifacts caused by respiratory motion, such as blur. The

Acquiring a four-dimensional computed tomography dataset using an external respiratory signal

International Nuclear Information System (INIS)

Vedam, S S; Keall, P J; Kini, V R; Mostafavi, H; Shukla, H P; Mohan, R

2003-01-01

Four-dimensional (4D) methods strive to achieve highly conformal radiotherapy, particularly for lung and breast tumours, in the presence of respiratory-induced motion of tumours and normal tissues. Four-dimensional radiotherapy accounts for respiratory motion during imaging, planning and radiation delivery, and requires a 4D CT image in which the internal anatomy motion as a function of the respiratory cycle can be quantified. The aims of our research were (a) to develop a method to acquire 4D CT images from a spiral CT scan using an external respiratory signal and (b) to examine the potential utility of 4D CT imaging. A commercially available respiratory motion monitoring system provided an 'external' tracking signal of the patient's breathing. Simultaneous recording of a TTL 'X-Ray ON' signal from the CT scanner indicated the start time of CT image acquisition, thus facilitating time stamping of all subsequent images. An over-sampled spiral CT scan was acquired using a pitch of 0.5 and scanner rotation time of 1.5 s. Each image from such a scan was sorted into an image bin that corresponded with the phase of the respiratory cycle in which the image was acquired. The complete set of such image bins accumulated over a respiratory cycle constitutes a 4D CT dataset. Four-dimensional CT datasets of a mechanical oscillator phantom and a patient undergoing lung radiotherapy were acquired. Motion artefacts were significantly reduced in the images in the 4D CT dataset compared to the three-dimensional (3D) images, for which respiratory motion was not accounted. Accounting for respiratory motion using 4D CT imaging is feasible and yields images with less distortion than 3D images. 4D images also contain respiratory motion information not available in a 3D CT image

Isotoxic dose escalation in the treatment of lung cancer by means of heterogeneous dose distributions in the presence of respiratory motion

DEFF Research Database (Denmark)

Baker, Mariwan; Nielsen, Morten; Hansen, Olfred

2011-01-01

To test, in the presence of intrafractional respiration movement, a margin recipe valid for a homogeneous and conformal dose distribution and to test whether the use of smaller margins combined with heterogeneous dose distributions allows an isotoxic dose escalation when respiratory motion...

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)

TH-EF-BRA-03: Assessment of Data-Driven Respiratory Motion-Compensation Methods for 4D-CBCT Image Registration and Reconstruction Using Clinical Datasets

Energy Technology Data Exchange (ETDEWEB)

Riblett, MJ; Weiss, E; Hugo, GD [Virginia Commonwealth University, Richmond, VA (United States); Christensen, GE [University of Iowa, Iowa City, IA (United States)

2016-06-15

Purpose: To evaluate the performance of a 4D-CBCT registration and reconstruction method that corrects for respiratory motion and enhances image quality under clinically relevant conditions. Methods: Building on previous work, which tested feasibility of a motion-compensation workflow using image datasets superior to clinical acquisitions, this study assesses workflow performance under clinical conditions in terms of image quality improvement. Evaluated workflows utilized a combination of groupwise deformable image registration (DIR) and image reconstruction. Four-dimensional cone beam CT (4D-CBCT) FDK reconstructions were registered to either mean or respiratory phase reference frame images to model respiratory motion. The resulting 4D transformation was used to deform projection data during the FDK backprojection operation to create a motion-compensated reconstruction. To simulate clinically realistic conditions, superior quality projection datasets were sampled using a phase-binned striding method. Tissue interface sharpness (TIS) was defined as the slope of a sigmoid curve fit to the lung-diaphragm boundary or to the carina tissue-airway boundary when no diaphragm was discernable. Image quality improvement was assessed in 19 clinical cases by evaluating mitigation of view-aliasing artifacts, tissue interface sharpness recovery, and noise reduction. Results: For clinical datasets, evaluated average TIS recovery relative to base 4D-CBCT reconstructions was observed to be 87% using fixed-frame registration alone; 87% using fixed-frame with motion-compensated reconstruction; 92% using mean-frame registration alone; and 90% using mean-frame with motion-compensated reconstruction. Soft tissue noise was reduced on average by 43% and 44% for the fixed-frame registration and registration with motion-compensation methods, respectively, and by 40% and 42% for the corresponding mean-frame methods. Considerable reductions in view aliasing artifacts were observed for each

TH-EF-BRA-03: Assessment of Data-Driven Respiratory Motion-Compensation Methods for 4D-CBCT Image Registration and Reconstruction Using Clinical Datasets

International Nuclear Information System (INIS)

Riblett, MJ; Weiss, E; Hugo, GD; Christensen, GE

2016-01-01

Purpose: To evaluate the performance of a 4D-CBCT registration and reconstruction method that corrects for respiratory motion and enhances image quality under clinically relevant conditions. Methods: Building on previous work, which tested feasibility of a motion-compensation workflow using image datasets superior to clinical acquisitions, this study assesses workflow performance under clinical conditions in terms of image quality improvement. Evaluated workflows utilized a combination of groupwise deformable image registration (DIR) and image reconstruction. Four-dimensional cone beam CT (4D-CBCT) FDK reconstructions were registered to either mean or respiratory phase reference frame images to model respiratory motion. The resulting 4D transformation was used to deform projection data during the FDK backprojection operation to create a motion-compensated reconstruction. To simulate clinically realistic conditions, superior quality projection datasets were sampled using a phase-binned striding method. Tissue interface sharpness (TIS) was defined as the slope of a sigmoid curve fit to the lung-diaphragm boundary or to the carina tissue-airway boundary when no diaphragm was discernable. Image quality improvement was assessed in 19 clinical cases by evaluating mitigation of view-aliasing artifacts, tissue interface sharpness recovery, and noise reduction. Results: For clinical datasets, evaluated average TIS recovery relative to base 4D-CBCT reconstructions was observed to be 87% using fixed-frame registration alone; 87% using fixed-frame with motion-compensated reconstruction; 92% using mean-frame registration alone; and 90% using mean-frame with motion-compensated reconstruction. Soft tissue noise was reduced on average by 43% and 44% for the fixed-frame registration and registration with motion-compensation methods, respectively, and by 40% and 42% for the corresponding mean-frame methods. Considerable reductions in view aliasing artifacts were observed for each

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

Respiratory effort from the photoplethysmogram.

Science.gov (United States)

Addison, Paul S

2017-03-01

The potential for a simple, non-invasive measure of respiratory effort based on the pulse oximeter signal - the photoplethysmogram or 'pleth' - was investigated in a pilot study. Several parameters were developed based on a variety of manifestations of respiratory effort in the signal, including modulation changes in amplitude, baseline, frequency and pulse transit times, as well as distinct baseline signal shifts. Thirteen candidate parameters were investigated using data from healthy volunteers. Each volunteer underwent a series of controlled respiratory effort maneuvers at various set flow resistances and respiratory rates. Six oximeter probes were tested at various body sites. In all, over three thousand pleth-based effort-airway pressure (EP) curves were generated across the various airway constrictions, respiratory efforts, respiratory rates, subjects, probe sites, and the candidate parameters considered. Regression analysis was performed to determine the existence of positive monotonic relationships between the respiratory effort parameters and resulting airway pressures. Six of the candidate parameters investigated exhibited a distinct positive relationship (poximeter probe and an ECG (P2E-Effort) and the other using two pulse oximeter probes placed at different peripheral body sites (P2-Effort); and baseline shifts in heart rate, (BL-HR-Effort). In conclusion, a clear monotonic relationship was found between several pleth-based parameters and imposed respiratory loadings at the mouth across a range of respiratory rates and flow constrictions. The results suggest that the pleth may provide a measure of changing upper airway dynamics indicative of the effort to breathe. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

Geographic miss of lung tumours due to respiratory motion: a comparison of 3D vs 4D PET/CT defined target volumes

International Nuclear Information System (INIS)

Callahan, Jason; Kron, Tomas; Siva, Shankar; Simoens, Nathalie; Edgar, Amanda; Everitt, Sarah; Schneider, Michal E; Hicks, Rodney J

2014-01-01

PET/CT scans acquired in the radiotherapy treatment position are typically performed without compensating for respiratory motion. The purpose of this study was to investigate geographic miss of lung tumours due to respiratory motion for target volumes defined on a standard 3D-PET/CT. 29 patients staged for pulmonary malignancy who completed both a 3D-PET/CT and 4D-PET/CT were included. A 3D-Gross Tumour Volume (GTV) was defined on the standard whole body PET/CT scan. Subsequently a 4D-GTV was defined on a 4D-PET/CT MIP. A 5 mm, 10 mm, 15 mm symmetrical and 15×10 mm asymmetrical Planning Target Volume (PTV) was created by expanding the 3D-GTV and 4D-GTV’s. A 3D conformal plan was generated and calculated to cover the 3D-PTV. The 3D plan was transferred to the 4D-PTV and analysed for geographic miss. Three types of miss were measured. Type 1: any part of the 4D-GTV outside the 3D-PTV. Type 2: any part of the 4D-PTV outside the 3D-PTV. Type 3: any part of the 4D-PTV receiving less than 95% of the prescribed dose. The lesion motion was measured to look at the association between lesion motion and geographic miss. When a standard 15 mm or asymmetrical PTV margin was used there were 1/29 (3%) Type 1 misses. This increased 7/29 (24%) for the 10 mm margin and 23/29 (79%) for a 5 mm margin. All patients for all margins had a Type 2 geographic miss. There was a Type 3 miss in 25 out of 29 cases in the 5, 10, and 15 mm PTV margin groups. The asymmetrical margin had one additional Type 3 miss. Pearson analysis showed a correlation (p < 0.01) between lesion motion and the severity of the different types of geographic miss. Without any form of motion suppression, the current standard of a 3D- PET/CT and 15 mm PTV margin employed for lung lesions has an increasing risk of significant geographic miss when tumour motion increases. Use of smaller asymmetric margins in the cranio-caudal direction does not comprise tumour coverage. Reducing PTV margins for volumes defined on 3D

Respiratory correlated cone beam CT

International Nuclear Information System (INIS)

Sonke, Jan-Jakob; Zijp, Lambert; Remeijer, Peter; Herk, Marcel van

2005-01-01

A cone beam computed tomography (CBCT) scanner integrated with a linear accelerator is a powerful tool for image guided radiotherapy. Respiratory motion, however, induces artifacts in CBCT, while the respiratory correlated procedures, developed to reduce motion artifacts in axial and helical CT are not suitable for such CBCT scanners. We have developed an alternative respiratory correlated procedure for CBCT and evaluated its performance. This respiratory correlated CBCT procedure consists of retrospective sorting in projection space, yielding subsets of projections that each corresponds to a certain breathing phase. Subsequently, these subsets are reconstructed into a four-dimensional (4D) CBCT dataset. The breathing signal, required for respiratory correlation, was directly extracted from the 2D projection data, removing the need for an additional respiratory monitor system. Due to the reduced number of projections per phase, the contrast-to-noise ratio in a 4D scan reduced by a factor 2.6-3.7 compared to a 3D scan based on all projections. Projection data of a spherical phantom moving with a 3 and 5 s period with and without simulated breathing irregularities were acquired and reconstructed into 3D and 4D CBCT datasets. The positional deviations of the phantoms center of gravity between 4D CBCT and fluoroscopy were small: 0.13±0.09 mm for the regular motion and 0.39±0.24 mm for the irregular motion. Motion artifacts, clearly present in the 3D CBCT datasets, were substantially reduced in the 4D datasets, even in the presence of breathing irregularities, such that the shape of the moving structures could be identified more accurately. Moreover, the 4D CBCT dataset provided information on the 3D trajectory of the moving structures, absent in the 3D data. Considerable breathing irregularities, however, substantially reduces the image quality. Data presented for three different lung cancer patients were in line with the results obtained from the phantom study. In

Planning Study Comparison of Real-Time Target Tracking and Four-Dimensional Inverse Planning for Managing Patient Respiratory Motion

International Nuclear Information System (INIS)

Zhang Peng; Hugo, Geoffrey D.; Yan Di

2008-01-01

Purpose: Real-time target tracking (RT-TT) and four-dimensional inverse planning (4D-IP) are two potential methods to manage respiratory target motion. In this study, we evaluated each method using the cumulative dose-volume criteria in lung cancer radiotherapy. Methods and Materials: Respiration-correlated computed tomography scans were acquired for 4 patients. Deformable image registration was applied to generate a displacement mapping for each phase image of the respiration-correlated computed tomography images. First, the dose distribution for the organs of interest obtained from an idealized RT-TT technique was evaluated, assuming perfect knowledge of organ motion and beam tracking. Inverse planning was performed on each phase image separately. The treatment dose to the organs of interest was then accumulated from the optimized plans. Second, 4D-IP was performed using the probability density function of respiratory motion. The beam arrangement, prescription dose, and objectives were consistent in both planning methods. The dose-volume and equivalent uniform dose in the target volume, lung, heart, and spinal cord were used for the evaluation. Results: The cumulative dose in the target was similar for both techniques. The equivalent uniform dose of the lung, heart, and spinal cord was 4.6 ± 2.2, 11 ± 4.4, and 11 ± 6.6 Gy for RT-TT with a 0-mm target margin, 5.2 ± 3.1, 12 ± 5.9, and 12 ± 7.8 Gy for RT-TT with a 2-mm target margin, and 5.3 ± 2.3, 11.9 ± 5.0, and 12 ± 5.6 Gy for 4D-IP, respectively. Conclusion: The results of our study have shown that 4D-IP can achieve plans similar to those achieved by RT-TT. Considering clinical implementation, 4D-IP could be a more reliable and practical method to manage patient respiration-induced motion

SU-E-P-41: Imaging Coordination of Cone Beam CT, On-Board Image Conjunction with Optical Image Guidance for SBRT Treatment with Respiratory Motion Management

International Nuclear Information System (INIS)

Liu, Y; Campbell, J

2015-01-01

Purpose: To spare normal tissue for SBRT lung/liver patients, especially for patients with significant tumor motion, image guided respiratory motion management has been widely implemented in clinical practice. The purpose of this study was to evaluate imaging coordination of cone beam CT, on-board X-ray image conjunction with optical image guidance for SBRT treatment with motion management. Methods: Currently in our clinic a Varian Novlis Tx was utilized for treating SBRT patients implementing CBCT. A BrainLAB X-ray ExacTrac imaging system in conjunction with optical guidance was primarily used for SRS patients. CBCT and X-ray imaging system were independently calibrated with 1.0 mm tolerance. For SBRT lung/liver patients, the magnitude of tumor motion was measured based-on 4DCT and the measurement was analyzed to determine if patients would be beneficial with respiratory motion management. For patients eligible for motion management, an additional CT with breath holding would be scanned and used as primary planning CT and as reference images for Cone beam CT. During the SBRT treatment, a CBCT with pause and continuing technology would be performed with patients holding breath, which may require 3–4 partially scanned CBCT to combine as a whole CBCT depending on how long patients capable of holding breath. After patients being setup by CBCT images, the ExactTrac X-ray imaging system was implemented with patients’ on-board X-ray images compared to breath holding CT-based DRR. Results: For breath holding patients SBRT treatment, after initially localizing patients with CBCT, we then position patients with ExacTrac X-ray and optical imaging system. The observed deviations of real-time optical guided position average at 3.0, 2.5 and 1.5 mm in longitudinal, vertical and lateral respectively based on 35 treatments. Conclusion: The respiratory motion management clinical practice improved our physician confidence level to give tighter tumor margin for sparing normal

Monitoring internal organ motion with continuous wave radar in CT

International Nuclear Information System (INIS)

Pfanner, Florian; Maier, Joscha; Allmendinger, Thomas; Flohr, Thomas; Kachelrieß, Marc

2013-01-01

Purpose: To avoid motion artifacts in medical imaging or to minimize the exposure of healthy tissues in radiation therapy, medical devices are often synchronized with the patient's respiratory motion. Today's respiratory motion monitors require additional effort to prepare the patients, e.g., mounting a motion belt or placing an optical reflector on the patient's breast. Furthermore, they are not able to measure internal organ motion without implanting markers. An interesting alternative to assess the patient's organ motion is continuous wave radar. The aim of this work is to design, implement, and evaluate such a radar system focusing on application in CT.Methods: The authors designed a radar system operating in the 860 MHz band to monitor the patient motion. In the intended application of the radar system, the antennas are located close to the patient's body inside the table of a CT system. One receive and four transmitting antennas are used to avoid the requirement of exact patient positioning. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example at the borderline between muscle and adipose tissue, or at the boundaries of organs. At present, the authors focus on the detection of respiratory motion. The radar system consists of the hardware mentioned above as well as of dedicated signal processing software to extract the desired information from the radar signal. The system was evaluated using simulations and measurements. To simulate the radar system, a simulation model based on radar and wave field equations was designed and 4D respiratory-gated CT data sets were used as input. The simulated radar signals and the measured data were processed in the same way. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the respiratory motion signal was recorded using a breast belt simultaneously with the radar measurements.Results: Concerning the

Free-breathing whole-heart 3D cine magnetic resonance imaging with prospective respiratory motion compensation.

Science.gov (United States)

Moghari, Mehdi H; Barthur, Ashita; Amaral, Maria E; Geva, Tal; Powell, Andrew J

2018-07-01

To develop and validate a new prospective respiratory motion compensation algorithm for free-breathing whole-heart 3D cine steady-state free precession (SSFP) imaging. In a 3D cine SSFP sequence, 4 excitations per cardiac cycle are re-purposed to prospectively track heart position. Specifically, their 1D image is reconstructed and routed into the scanner's standard diaphragmatic navigator processing system. If all 4 signals are in end-expiration, cine image data from the entire cardiac cycle is accepted for image reconstruction. Prospective validation was carried out in patients (N = 17) by comparing in each a conventional breath-hold 2D cine ventricular short-axis stack and a free-breathing whole-heart 3D cine data set. All 3D cine SSFP acquisitions were successful and the mean scan time was 5.9 ± 2.7 min. Left and right ventricular end-diastolic, end-systolic, and stroke volumes by 3D cine SSFP were all larger than those from 2D cine SSFP. This bias was 3D cine images had a lower ventricular blood-to-myocardium contrast ratio, contrast-to-noise ratio, mass, and subjective quality score. The novel prospective respiratory motion compensation method for 3D cine SSFP imaging was robust and efficient and yielded slightly larger ventricular volumes and lower mass compared to breath-hold 2D cine imaging. Magn Reson Med 80:181-189, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Cardiac and Respiratory Parameter Estimation Using Head-mounted Motion-sensitive Sensors

Directory of Open Access Journals (Sweden)

J. Hernandez

2015-05-01

Full Text Available This work explores the feasibility of using motion-sensitive sensors embedded in Google Glass, a head-mounted wearable device, to robustly measure physiological signals of the wearer. In particular, we develop new methods to use Glass’s accelerometer, gyroscope, and camera to extract pulse and respiratory waves of 12 participants during a controlled experiment. We show it is possible to achieve a mean absolute error of 0.82 beats per minute (STD: 1.98 for heart rate and 0.6 breaths per minute (STD: 1.19 for respiration rate when considering different observation windows and combinations of sensors. Moreover, we show that a head-mounted gyroscope sensor shows improved performance versus more commonly explored sensors such as accelerometers and demonstrate that a head-mounted camera is a novel and promising method to capture the physiological responses of the wearer. These findings included testing across sitting, supine, and standing postures before and after physical exercise.

Respiratory motion sampling in 4DCT reconstruction for radiotherapy

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Chi Yuwei; Liang Jian; Qin Xu; Yan Di [Department of Radiation Oncology, Columbia University, New York, New York 10032 (United States); Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan 48073 (United States)

2012-04-15

Purpose: Phase-based and amplitude-based sorting techniques are commonly used in four-dimensional CT (4DCT) reconstruction. However, effect of these sorting techniques on 4D dose calculation has not been explored. In this study, the authors investigated a candidate 4DCT sorting technique by comparing its 4D dose calculation accuracy with that for phase-based and amplitude-based sorting techniques.Method: An optimization model was formed using organ motion probability density function (PDF) in the 4D dose convolution. The objective function for optimization was defined as the maximum difference between the expected 4D dose in organ of interest and the 4D dose calculated using a 4DCT sorted by a candidate sampling method. Sorting samples, as optimization variables, were selected on the respiratory motion PDF assessed during the CT scanning. Breathing curves obtained from patients' 4DCT scanning, as well as 3D dose distribution from treatment planning, were used in the study. Given the objective function, a residual error analysis was performed, and k-means clustering was found to be an effective sampling scheme to improve the 4D dose calculation accuracy and independent with the patient-specific dose distribution. Results: Patient data analysis demonstrated that the k-means sampling was superior to the conventional phase-based and amplitude-based sorting and comparable to the optimal sampling results. For phase-based sorting, the residual error in 4D dose calculations may not be further reduced to an acceptable accuracy after a certain number of phases, while for amplitude-based sorting, k-means sampling, and the optimal sampling, the residual error in 4D dose calculations decreased rapidly as the number of 4DCT phases increased to 6.Conclusion: An innovative phase sorting method (k-means method) is presented in this study. The method is dependent only on tumor motion PDF. It could provide a way to refine the phase sorting in 4DCT reconstruction and is effective

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

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

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

Audiovisual biofeedback improves motion prediction accuracy.

Science.gov (United States)

Pollock, Sean; Lee, Danny; Keall, Paul; Kim, Taeho

2013-04-01

The accuracy of motion prediction, utilized to overcome the system latency of motion management radiotherapy systems, is hampered by irregularities present in the patients' respiratory pattern. Audiovisual (AV) biofeedback has been shown to reduce respiratory irregularities. The aim of this study was to test the hypothesis that AV biofeedback improves the accuracy of motion prediction. An AV biofeedback system combined with real-time respiratory data acquisition and MR images were implemented in this project. One-dimensional respiratory data from (1) the abdominal wall (30 Hz) and (2) the thoracic diaphragm (5 Hz) were obtained from 15 healthy human subjects across 30 studies. The subjects were required to breathe with and without the guidance of AV biofeedback during each study. The obtained respiratory signals were then implemented in a kernel density estimation prediction algorithm. For each of the 30 studies, five different prediction times ranging from 50 to 1400 ms were tested (150 predictions performed). Prediction error was quantified as the root mean square error (RMSE); the RMSE was calculated from the difference between the real and predicted respiratory data. The statistical significance of the prediction results was determined by the Student's t-test. Prediction accuracy was considerably improved by the implementation of AV biofeedback. Of the 150 respiratory predictions performed, prediction accuracy was improved 69% (103/150) of the time for abdominal wall data, and 78% (117/150) of the time for diaphragm data. The average reduction in RMSE due to AV biofeedback over unguided respiration was 26% (p biofeedback improves prediction accuracy. This would result in increased efficiency of motion management techniques affected by system latencies used in radiotherapy.

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

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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.

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

SU-G-BRA-13: An Advanced Deformable Lung Phantom for Analyzing the Dosimetric Impact of Respiratory Motion

International Nuclear Information System (INIS)

Shin, D; Kang, S; Kim, D; Kim, T; Kim, K; Cho, M; Suh, T

2016-01-01

Purpose: The difference between three-dimensional (3D) and four-dimensional (4D) dose is affected by factors such as tumor size and motion. To quantitatively analyze the effects of these factors, a phantom that can independently control for each factor is required. The purpose of this study is to develop a deformable lung phantom with the above attributes and evaluate characteristics. Methods: A phantom was designed to simulate diaphragm motion with amplitude in the range 1 to 7 cm and various periods of regular breathing. To simulate different size tumors, tumors were produced by pouring liquid silicone into custom molds created by a 3D printer. The accuracy of phantom diaphragm motion was assessed using calipers and protractor. To control tumor motion, tumor trajectories were evaluated using 4D computed tomography (CT), and diaphragm-tumor correlation curve was calculated by curve fitting method. Three-dimensional dose and 4D dose were calculated and compared according to tumor motion. Results: The accuracy of phantom diaphragm motion was less than 1 mm. Maximum tumor motion amplitudes in the left-right and anterior-posterior directions were 0.08 and 0.12 cm, respectively, in a 10 cm"3 tumor, and 0.06 and 0.27 cm, respectively, in a 90 cm"3 tumor. The diaphragm-tumor correlation curve showed that tumor motion in the superior-inferior direction was increased with increasing diaphragm motion. In the 10 cm"3 tumor, the tumor motion was larger than the 90 cm"3 tumor. According to tumor motion, variation of dose difference between 3D and 4D was identified. Conclusion: The developed phantom can independently control factors such as tumor size and motion. In potentially, this phantom can be used to quantitatively analyze the dosimetric impact of respiratory motion according to the factors that influence the difference between 3D and 4D dose. This research was supported by the Mid-career Researcher Program through NRF funded by the Ministry of Science, ICT & Future

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.

Respiratory muscle function in infants with spinal muscular atrophy type I.

Science.gov (United States)

Finkel, Richard S; Weiner, Daniel J; Mayer, Oscar H; McDonough, Joseph M; Panitch, Howard B

2014-12-01

To determine the feasibility and safety of respiratory muscle function testing in weak infants with a progressive neuromuscular disorder. Respiratory insufficiency is the major cause of morbidity and mortality in infants with spinal muscular atrophy type I (SMA-I). Tests of respiratory muscle strength, endurance, and breathing patterns can be performed safely in SMA-I infants. Useful data can be collected which parallels the clinical course of pulmonary function in SMA-I. An exploratory study of respiratory muscle function testing and breathing patterns in seven infants with SMA-I seen in our neuromuscular clinic. Measurements were made at initial study visit and, where possible, longitudinally over time. We measured maximal inspiratory (MIP) and transdiaphragmatic pressures, mean transdiaphragmatic pressure, airway occlusion pressure at 100 msec of inspiration, inspiratory and total respiratory cycle time, and aspects of relative thoracoabdominal motion using respiratory inductive plethysmography (RIP). The tension time index of the diaphragm and of the respiratory muscles, phase angle (Φ), phase relation during the total breath, and labored breathing index were calculated. Age at baseline study was 54-237 (median 131) days. Reliable data were obtained safely for MIP, phase angle, labored breathing index, and the invasive and non-invasive tension time indices, even in very weak infants. Data obtained corresponded to the clinical estimate of severity and predicted the need for respiratory support. The testing employed was both safe and feasible. Measurements of MIP and RIP are easily performed tests that are well tolerated and provide clinically useful information for infants with SMA-I. © 2014 Wiley Periodicals, Inc.

Relation of external surface to internal tumor motion studied with cine CT

International Nuclear Information System (INIS)

Chi, P.-C.M.; Balter, Peter; Luo Dershan; Mohan, Radhe; Pan Tinsu

2006-01-01

The accuracy of delivering gated-radiation therapy to lung tumors using an external respiratory surrogate relies on not only interfractional and intrafractional reproducibility, but also a strong correlation between external motion and internal tumor motion. The purpose of this work was to use the cine images acquired by four-dimensional computed tomography acquisition protocol to study the relation between external surface motion and internal tumor motion. The respiratory phase information of tumor motion and chest wall motion was measured on the cine images using a proposed region-of-interest (ROI) method and compared to measurement of an external respiratory monitoring device. On eight lung patient data sets, the phase shifts were measured between (1) the signal of a real-time positioning-management (RPM) respiratory monitoring device placed in the abdominal region and four surface locations on the chest wall (2) the RPM signal in the abdominal region and tumor motions, and (3) chest wall surface motions and tumor motions. Respiratory waveforms measured at different surface locations during the same respiratory cycle often varied and had significant phase shifts. Seven of the 8 patients showed the abdominal motion leading chest wall motion. The best correlation (smallest phase shift) was found between the abdominal motion and the superior-inferior (S-I) tumor motion. A wide range of phase shifts was observed between external surface motion and tumor anterior-posterior (A-P)/lateral motion. The result supported the placement of the RPM block in the abdominal region and suggested that during a gated therapy utilizing the RPM system, it is necessary to place the RPM block at the same location as it is during treatment simulation in order to reduce potential errors introduced by the position of the RPM block. Correlations between external motions and lateral/A-P tumor motions were inconclusive due to a combination of patient selection and the limitation of the ROI

Synchrony - Cyberknife Respiratory Compensation Technology

International Nuclear Information System (INIS)

Ozhasoglu, Cihat; Saw, Cheng B.; Chen Hungcheng; Burton, Steven; Komanduri, Krishna; Yue, Ning J.; Huq, Saiful M.; Heron, Dwight E.

2008-01-01

Studies of organs in the thorax and abdomen have shown that these organs can move as much as 40 mm due to respiratory motion. Without compensation for this motion during the course of external beam radiation therapy, the dose coverage to target may be compromised. On the other hand, if compensation of this motion is by expansion of the margin around the target, a significant volume of normal tissue may be unnecessarily irradiated. In hypofractionated regimens, the issue of respiratory compensation becomes an important factor and is critical in single-fraction extracranial radiosurgery applications. CyberKnife is an image-guided radiosurgery system that consists of a 6-MV LINAC mounted to a robotic arm coupled through a control loop to a digital diagnostic x-ray imaging system. The robotic arm can point the beam anywhere in space with 6 degrees of freedom, without being constrained to a conventional isocenter. The CyberKnife has been recently upgraded with a real-time respiratory tracking and compensation system called Synchrony. Using external markers in conjunction with diagnostic x-ray images, Synchrony helps guide the robotic arm to move the radiation beam in real time such that the beam always remains aligned with the target. With the aid of Synchrony, the tumor motion can be tracked in three-dimensional space, and the motion-induced dosimetric change to target can be minimized with a limited margin. The working principles, advantages, limitations, and our clinical experience with this new technology will be discussed

Intrafractional Baseline Shift or Drift of Lung Tumor Motion During Gated Radiation Therapy With a Real-Time Tumor-Tracking System

International Nuclear Information System (INIS)

Takao, Seishin; Miyamoto, Naoki; Matsuura, Taeko; Onimaru, Rikiya; Katoh, Norio; Inoue, Tetsuya; Sutherland, Kenneth Lee; Suzuki, Ryusuke; Shirato, Hiroki; Shimizu, Shinichi

2016-01-01

Purpose: To investigate the frequency and amplitude of baseline shift or drift (shift/drift) of lung tumors in stereotactic body radiation therapy (SBRT), using a real-time tumor-tracking radiation therapy (RTRT) system. Methods and Materials: Sixty-eight patients with peripheral lung tumors were treated with SBRT using the RTRT system. One of the fiducial markers implanted near the tumor was used for the real-time monitoring of the intrafractional tumor motion every 0.033 seconds by the RTRT system. When baseline shift/drift is determined by the system, the position of the treatment couch is adjusted to compensate for the shift/drift. Therefore, the changes in the couch position correspond to the baseline shift/drift in the tumor motion. The frequency and amount of adjustment to the couch positions in the left-right (LR), cranio-caudal (CC), and antero-posterior (AP) directions have been analyzed for 335 fractions administered to 68 patients. Results: The average change in position of the treatment couch during the treatment time was 0.45 ± 2.23 mm (mean ± standard deviation), −1.65 ± 5.95 mm, and 1.50 ± 2.54 mm in the LR, CC, and AP directions, respectively. Overall the baseline shift/drift occurs toward the cranial and posterior directions. The incidence of baseline shift/drift exceeding 3 mm was 6.0%, 15.5%, 14.0%, and 42.1% for the LR, CC, AP, and for the square-root of sum of 3 directions, respectively, within 10 minutes of the start of treatment, and 23.0%, 37.6%, 32.5%, and 71.6% within 30 minutes. Conclusions: Real-time monitoring and frequent adjustments of the couch position and/or adding appropriate margins are suggested to be essential to compensate for possible underdosages due to baseline shift/drift in SBRT for lung cancers.

Use of the temporal median and trimmed mean mitigates effects of respiratory motion in multiple-acquisition abdominal diffusion imaging

International Nuclear Information System (INIS)

Jerome, N P; Orton, M R; D’Arcy, J A; Leach, M O; Collins, D J; Feiweier, T; Tunariu, N; Koh, D-M

2015-01-01

Respiratory motion commonly confounds abdominal diffusion-weighted magnetic resonance imaging, where averaging of successive samples at different parts of the respiratory cycle, performed in the scanner, manifests the motion as blurring of tissue boundaries and structural features and can introduce bias into calculated diffusion metrics. Storing multiple averages separately allows processing using metrics other than the mean; in this prospective volunteer study, median and trimmed mean values of signal intensity for each voxel over repeated averages and diffusion-weighting directions are shown to give images with sharper tissue boundaries and structural features for moving tissues, while not compromising non-moving structures. Expert visual scoring of derived diffusion maps is significantly higher for the median than for the mean, with modest improvement from the trimmed mean. Diffusion metrics derived from mono- and bi-exponential diffusion models are comparable for non-moving structures, demonstrating a lack of introduced bias from using the median. The use of the median is a simple and computationally inexpensive alternative to complex and expensive registration algorithms, requiring only additional data storage (and no additional scanning time) while returning visually superior images that will facilitate the appropriate placement of regions-of-interest when analysing abdominal diffusion-weighted magnetic resonance images, for assessment of disease characteristics and treatment response. (note)

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...

Respiratory-induced prostate motion: quantification and characterization

International Nuclear Information System (INIS)

Malone, Shawn; Crook, Juanita M.; Kendal, Wayne S.; Zanto, Janos S.

2000-01-01

Purpose: The precise localization of the prostate is critical for dose-escalated conformal radiotherapy. This study identifies and characterizes a potential cause of inaccurate prostatic localization--respiratory-induced movement. Methods and Materials: Prostate movement during respiration was measured fluoroscopically using implanted gold fiducial markers. Twenty sequential patients with CT 1 -T 3 N 0 M 0 prostate carcinoma were evaluated prone, immobilized in customized thermoplastic shells. A second 20 patients were evaluated both prone (with and without their thermoplastic shells) and supine (without their shells). Results: When the patients were immobilized prone in thermoplastic shells, the prostate moved synchronously with respiration. In the study the prostate was displaced a mean distance of 3.3 ± 1.8 (SD) mm (range, 1-10.2 mm), with 23% (9/40) of the displacements being 4 mm or greater. The respiratory-associated prostate movement decreased significantly when the thermoplastic shells were removed. Conclusion: Significant prostate movement can be induced by respiration when patients are immobilized in thermoplastic shells. This movement presumably is related to transmitted intraabdominal pressure within the confined space of the shells. Careful attention to the details of immobilization and to the possibility of respiratory-induced prostate movements is important when employing small field margins in prostatic radiotherapy

SU-E-J-110: Dosimetric Analysis of Respiratory Motion Based On Four-Dimensional Dose Accumulation in Liver Stereotactic Body Radiotherapy

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Kang, S; Kim, D; Kim, T; Kim, K; Cho, M; Shin, D; Suh, T [The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of); Kim, S [Virginia Commonwealth University, Richmond, VA (United States); Park, S [Uijeongbu St.Mary’s Hospital, GyeongGi-Do (Korea, Republic of)

2015-06-15

Purpose: Respiratory motion in thoracic and abdominal region could lead to significant underdosing of target and increased dose to healthy tissues. The aim of this study is to evaluate the dosimetric effect of respiratory motion in conventional 3D dose by comparing 4D deformable dose in liver stereotactic body radiotherapy (SBRT). Methods: Five patients who had previously treated liver SBRT were included in this study. Four-dimensional computed tomography (4DCT) images with 10 phases for all patients were acquired on multi-slice CT scanner (Siemens, Somatom definition). Conventional 3D planning was performed using the average intensity projection (AIP) images. 4D dose accumulation was calculated by summation of dose distribution for all phase images of 4DCT using deformable image registration (DIR) . The target volume and normal organs dose were evaluated with the 4D dose and compared with those from 3D dose. And also, Index of achievement (IOA) which assesses the consistency between planned dose and prescription dose was used to compare target dose distribution between 3D and 4D dose. Results: Although the 3D dose calculation considered the moving target coverage, significant differences of various dosimetric parameters between 4D and 3D dose were observed in normal organs and PTV. The conventional 3D dose overestimated dose to PTV, however, there was no significant difference for GTV. The average difference of IOA which become ‘1’ in an ideal case was 3.2% in PTV. The average difference of liver and duodenum was 5% and 16% respectively. Conclusion: 4D dose accumulation which can provide dosimetric effect of respiratory motion has a possibility to predict the more accurate delivered dose to target and normal organs and improve treatment accuracy. This work was supported by the Radiation Technology R&D program (No. 2013M2A2A7043498) and the Mid-career Researcher Program (2014R1A2A1A10050270) through the National Research Foundation of Korea funded by the

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

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

SU-G-BRA-13: An Advanced Deformable Lung Phantom for Analyzing the Dosimetric Impact of Respiratory Motion

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Shin, D; Kang, S; Kim, D; Kim, T; Kim, K; Cho, M; Suh, T [Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of)

2016-06-15

Purpose: The difference between three-dimensional (3D) and four-dimensional (4D) dose is affected by factors such as tumor size and motion. To quantitatively analyze the effects of these factors, a phantom that can independently control for each factor is required. The purpose of this study is to develop a deformable lung phantom with the above attributes and evaluate characteristics. Methods: A phantom was designed to simulate diaphragm motion with amplitude in the range 1 to 7 cm and various periods of regular breathing. To simulate different size tumors, tumors were produced by pouring liquid silicone into custom molds created by a 3D printer. The accuracy of phantom diaphragm motion was assessed using calipers and protractor. To control tumor motion, tumor trajectories were evaluated using 4D computed tomography (CT), and diaphragm-tumor correlation curve was calculated by curve fitting method. Three-dimensional dose and 4D dose were calculated and compared according to tumor motion. Results: The accuracy of phantom diaphragm motion was less than 1 mm. Maximum tumor motion amplitudes in the left-right and anterior-posterior directions were 0.08 and 0.12 cm, respectively, in a 10 cm{sup 3} tumor, and 0.06 and 0.27 cm, respectively, in a 90 cm{sup 3} tumor. The diaphragm-tumor correlation curve showed that tumor motion in the superior-inferior direction was increased with increasing diaphragm motion. In the 10 cm{sup 3} tumor, the tumor motion was larger than the 90 cm{sup 3} tumor. According to tumor motion, variation of dose difference between 3D and 4D was identified. Conclusion: The developed phantom can independently control factors such as tumor size and motion. In potentially, this phantom can be used to quantitatively analyze the dosimetric impact of respiratory motion according to the factors that influence the difference between 3D and 4D dose. This research was supported by the Mid-career Researcher Program through NRF funded by the Ministry of Science

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.

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.

Motion robust high resolution 3D free-breathing pulmonary MRI using dynamic 3D image self-navigator.

Science.gov (United States)

Jiang, Wenwen; Ong, Frank; Johnson, Kevin M; Nagle, Scott K; Hope, Thomas A; Lustig, Michael; Larson, Peder E Z

2018-06-01

To achieve motion robust high resolution 3D free-breathing pulmonary MRI utilizing a novel dynamic 3D image navigator derived directly from imaging data. Five-minute free-breathing scans were acquired with a 3D ultrashort echo time (UTE) sequence with 1.25 mm isotropic resolution. From this data, dynamic 3D self-navigating images were reconstructed under locally low rank (LLR) constraints and used for motion compensation with one of two methods: a soft-gating technique to penalize the respiratory motion induced data inconsistency, and a respiratory motion-resolved technique to provide images of all respiratory motion states. Respiratory motion estimation derived from the proposed dynamic 3D self-navigator of 7.5 mm isotropic reconstruction resolution and a temporal resolution of 300 ms was successful for estimating complex respiratory motion patterns. This estimation improved image quality compared to respiratory belt and DC-based navigators. Respiratory motion compensation with soft-gating and respiratory motion-resolved techniques provided good image quality from highly undersampled data in volunteers and clinical patients. An optimized 3D UTE sequence combined with the proposed reconstruction methods can provide high-resolution motion robust pulmonary MRI. Feasibility was shown in patients who had irregular breathing patterns in which our approach could depict clinically relevant pulmonary pathologies. Magn Reson Med 79:2954-2967, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Adaptation of the modified Bouc–Wen model to compensate for hysteresis in respiratory motion for the list-mode binning of cardiac SPECT and PET acquisitions: Testing using MRI

International Nuclear Information System (INIS)

Dasari, Paul K. R.; Shazeeb, Mohammed Salman; Könik, Arda; Lindsay, Clifford; Mukherjee, Joyeeta M.; Johnson, Karen L.; King, Michael A.

2014-01-01

Purpose: Binning list-mode acquisitions as a function of a surrogate signal related to respiration has been employed to reduce the impact of respiratory motion on image quality in cardiac emission tomography (SPECT and PET). Inherent in amplitude binning is the assumption that there is a monotonic relationship between the amplitude of the surrogate signal and respiratory motion of the heart. This assumption is not valid in the presence of hysteresis when heart motion exhibits a different relationship with the surrogate during inspiration and expiration. The purpose of this study was to investigate the novel approach of using the Bouc–Wen (BW) model to provide a signal accounting for hysteresis when binning list-mode data with the goal of thereby improving motion correction. The study is based on the authors’ previous observations that hysteresis between chest and abdomen markers was indicative of hysteresis between abdomen markers and the internal motion of the heart. Methods: In 19 healthy volunteers, they determined the internal motion of the heart and diaphragm in the superior–inferior direction during free breathing using MRI navigators. A visual tracking system (VTS) synchronized with MRI acquisition tracked the anterior–posterior motions of external markers placed on the chest and abdomen. These data were employed to develop and test the Bouc–Wen model by inputting the VTS derived chest and abdomen motions into it and using the resulting output signals as surrogates for cardiac motion. The data of the volunteers were divided into training and testing sets. The training set was used to obtain initial values for the model parameters for all of the volunteers in the set, and for set members based on whether they were or were not classified as exhibiting hysteresis using a metric derived from the markers. These initial parameters were then employed with the testing set to estimate output signals. Pearson’s linear correlation coefficient between the

Imaging of respiratory muscles in neuromuscular disease: A review.

Science.gov (United States)

Harlaar, L; Ciet, P; van der Ploeg, A T; Brusse, E; van der Beek, N A M E; Wielopolski, P A; de Bruijne, M; Tiddens, H A W M; van Doorn, P A

2018-03-01

Respiratory muscle weakness frequently occurs in patients with neuromuscular disease. Measuring respiratory function with standard pulmonary function tests provides information about the contribution of all respiratory muscles, the lungs and airways. Imaging potentially enables the study of different respiratory muscles, including the diaphragm, separately. In this review, we provide an overview of imaging techniques used to study respiratory muscles in neuromuscular disease. We identified 26 studies which included a total of 573 patients with neuromuscular disease. Imaging of respiratory muscles was divided into static and dynamic techniques. Static techniques comprise chest radiography, B-mode (brightness mode) ultrasound, CT and MRI, and are used to assess the position and thickness of the diaphragm and the other respiratory muscles. Dynamic techniques include fluoroscopy, M-mode (motion mode) ultrasound and MRI, used to assess diaphragm motion in one or more directions. We discuss how these imaging techniques relate with spirometric values and whether these can be used to study the contribution of the different respiratory muscles in patients with neuromuscular disease. Copyright © 2017. Published by Elsevier B.V.

Contactless respiratory monitoring system for magnetic resonance imaging applications using a laser range sensor

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Krug Johannes W.

2016-09-01

Full Text Available During a magnetic resonance imaging (MRI exam, a respiratory signal can be required for different purposes, e.g. for patient monitoring, motion compensation or for research studies such as in functional MRI. In addition, respiratory information can be used as a biofeedback for the patient in order to control breath holds or shallow breathing. To reduce patient preparation time or distortions of the MR imaging system, we propose the use of a contactless approach for gathering information about the respiratory activity. An experimental setup based on a commercially available laser range sensor was used to detect respiratory induced motion of the chest or abdomen. This setup was tested using a motion phantom and different human subjects in an MRI scanner. A nasal airflow sensor served as a reference. For both, the phantom as well as the different human subjects, the motion frequency was precisely measured. These results show that a low cost, contactless, laser-based approach can be used to obtain information about the respiratory motion during an MRI exam.

MRI-Based Nonrigid Motion Correction in Simultaneous PET/MRI

Science.gov (United States)

Chun, Se Young; Reese, Timothy G.; Ouyang, Jinsong; Guerin, Bastien; Catana, Ciprian; Zhu, Xuping; Alpert, Nathaniel M.; El Fakhri, Georges

2014-01-01

Respiratory and cardiac motion is the most serious limitation to whole-body PET, resulting in spatial resolution close to 1 cm. Furthermore, motion-induced inconsistencies in the attenuation measurements often lead to significant artifacts in the reconstructed images. Gating can remove motion artifacts at the cost of increased noise. This paper presents an approach to respiratory motion correction using simultaneous PET/MRI to demonstrate initial results in phantoms, rabbits, and nonhuman primates and discusses the prospects for clinical application. Methods Studies with a deformable phantom, a free-breathing primate, and rabbits implanted with radioactive beads were performed with simultaneous PET/MRI. Motion fields were estimated from concurrently acquired tagged MR images using 2 B-spline nonrigid image registration methods and incorporated into a PET list-mode ordered-subsets expectation maximization algorithm. Using the measured motion fields to transform both the emission data and the attenuation data, we could use all the coincidence data to reconstruct any phase of the respiratory cycle. We compared the resulting SNR and the channelized Hotelling observer (CHO) detection signal-to-noise ratio (SNR) in the motion-corrected reconstruction with the results obtained from standard gating and uncorrected studies. Results Motion correction virtually eliminated motion blur without reducing SNR, yielding images with SNR comparable to those obtained by gating with 5–8 times longer acquisitions in all studies. The CHO study in dynamic phantoms demonstrated a significant improvement (166%–276%) in lesion detection SNR with MRI-based motion correction as compared with gating (P < 0.001). This improvement was 43%–92% for large motion compared with lesion detection without motion correction (P < 0.001). CHO SNR in the rabbit studies confirmed these results. Conclusion Tagged MRI motion correction in simultaneous PET/MRI significantly improves lesion detection

Influence of respiratory motion in the delineation of treatment volumes using CT images; Influencia del movimiento respiratorio en la delimiacion de volumenes de tratamiento mediante imagenes TC

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Rodriguez Romero, R.; Castro Tejero, P.

2011-07-01

The radiation treatments are based on geometric information and density of the CT images obtained for each patient. As a result of the motion blur produced in the imaging studies, the sizes, shapes and densities of the structures can be altered. The aim of this study was to determine the magnitude of these variations caused by respiratory motion in the CT study according to the conditions of image acquisition.

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.)

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.

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.

Reduction of respiratory ghosting motion artifacts in conventional two-dimensional multi-slice Cartesian turbo spin-echo: which k-space filling order is the best?

Science.gov (United States)

Inoue, Yuuji; Yoneyama, Masami; Nakamura, Masanobu; Takemura, Atsushi

2018-06-01

The two-dimensional Cartesian turbo spin-echo (TSE) sequence is widely used in routine clinical studies, but it is sensitive to respiratory motion. We investigated the k-space orders in Cartesian TSE that can effectively reduce motion artifacts. The purpose of this study was to demonstrate the relationship between k-space order and degree of motion artifacts using a moving phantom. We compared the degree of motion artifacts between linear and asymmetric k-space orders. The actual spacing of ghost artifacts in the asymmetric order was doubled compared with that in the linear order in the free-breathing situation. The asymmetric order clearly showed less sensitivity to incomplete breath-hold at the latter half of the imaging period. Because of the actual number of partitions of the k-space and the temporal filling order, the asymmetric k-space order of Cartesian TSE was superior to the linear k-space order for reduction of ghosting motion artifacts.

A Unifying model of perfusion and motion applied to reconstruction of sparsely sampled free-breathing myocardial perfusion MRI

DEFF Research Database (Denmark)

Pedersen, Henrik; Ólafsdóttir, Hildur; Larsen, Rasmus

2010-01-01

The clinical potential of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is currently limited by respiratory induced motion of the heart. This paper presents a unifying model of perfusion and motion in which respiratory motion becomes an integral part of myocardial perfusion...... quantification. Hence, the need for tedious manual motion correction prior to perfusion quantification is avoided. In addition, we demonstrate that the proposed framework facilitates the process of reconstructing DCEMRI from sparsely sampled data in the presence of respiratory motion. The paper focuses primarily...... on the underlying theory of the proposed framework, but shows in vivo results of respiratory motion correction and simulation results of reconstructing sparsely sampled data....

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

Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition.

Science.gov (United States)

Wang, Fu-Tai; Chan, Hsiao-Lung; Wang, Chun-Li; Jian, Hung-Ming; Lin, Sheng-Hsiung

2015-07-07

Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD) can decompose a signal into several intrinsic mode functions (IMFs) that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method.

SU-D-17A-07: Development and Evaluation of a Prototype Ultrasonography Respiratory Monitoring System for 4DCT Reconstruction

International Nuclear Information System (INIS)

Yan, P; Cheng, S; Chao, C; Jain, A

2014-01-01

Purpose: Respiratory motion artifacts are commonly seen in the abdominal and thoracic CT images. A Real-time Position Management (RPM) system is integrated with CT simulator using abdominal surface as a surrogate for tracking the patient respiratory motion. The respiratory-correlated four-dimensional computed tomography (4DCT) is then reconstructed by GE advantage software. However, there are still artifacts due to inaccurate respiratory motion detecting and sorting methods. We developed an Ultrasonography Respiration Monitoring (URM) system which can directly monitor diaphragm motion to detect respiratory cycles. We also developed a new 4DCT sorting and motion estimation method to reduce the respiratory motion artifacts. The new 4DCT system was compared with RPM and the GE 4DCT system. Methods: Imaging from a GE CT scanner was simultaneously correlated with both the RPM and URM to detect respiratory motion. A radiation detector, Blackcat GM-10, recorded the X-ray on/off and synchronized with URM. The diaphragm images were acquired with Ultrasonix RP system. The respiratory wave was derived from diaphragm images and synchronized with CT scanner. A more precise peaks and valleys detection tool was developed and compared with RPM. The motion is estimated for the slices which are not in the predefined respiratory phases by using block matching and optical flow method. The CT slices were then sorted into different phases and reconstructed, compared with the images reconstructed from GE Advantage software using respiratory wave produced from RPM system. Results: The 4DCT images were reconstructed for eight patients. The discontinuity at the diaphragm level due to an inaccurate identification of phases by the RPM was significantly improved by URM system. Conclusion: Our URM 4DCT system was evaluated and compared with RPM and GE 4DCT system. The new system is user friendly and able to reduce motion artifacts. It also has the potential to monitor organ motion during

Optimizing 4DCBCT projection allocation to respiratory bins

International Nuclear Information System (INIS)

O’Brien, Ricky T; Kipritidis, John; Shieh, Chun-Chien; Keall, Paul J

2014-01-01

4D cone beam computed tomography (4DCBCT) is an emerging image guidance strategy used in radiotherapy where projections acquired during a scan are sorted into respiratory bins based on the respiratory phase or displacement. 4DCBCT reduces the motion blur caused by respiratory motion but increases streaking artefacts due to projection under-sampling as a result of the irregular nature of patient breathing and the binning algorithms used. For displacement binning the streak artefacts are so severe that displacement binning is rarely used clinically. The purpose of this study is to investigate if sharing projections between respiratory bins and adjusting the location of respiratory bins in an optimal manner can reduce or eliminate streak artefacts in 4DCBCT images. We introduce a mathematical optimization framework and a heuristic solution method, which we will call the optimized projection allocation algorithm, to determine where to position the respiratory bins and which projections to source from neighbouring respiratory bins. Five 4DCBCT datasets from three patients were used to reconstruct 4DCBCT images. Projections were sorted into respiratory bins using equispaced, equal density and optimized projection allocation. The standard deviation of the angular separation between projections was used to assess streaking and the consistency of the segmented volume of a fiducial gold marker was used to assess motion blur. The standard deviation of the angular separation between projections using displacement binning and optimized projection allocation was 30%–50% smaller than conventional phase based binning and 59%–76% smaller than conventional displacement binning indicating more uniformly spaced projections and fewer streaking artefacts. The standard deviation in the marker volume was 20%–90% smaller when using optimized projection allocation than using conventional phase based binning suggesting more uniform marker segmentation and less motion blur. Images

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)

Three-Dimensional Intrafractional Motion of Breast During Tangential Breast Irradiation Monitored With High-Sampling Frequency Using a Real-Time Tumor-Tracking Radiotherapy System

International Nuclear Information System (INIS)

Kinoshita, Rumiko; Shimizu, Shinichi; Taguchi, Hiroshi; Katoh, Norio; Fujino, Masaharu; Onimaru, Rikiya; Aoyama, Hidefumi; Katoh, Fumi; Omatsu, Tokuhiko; Ishikawa, Masayori; Shirato, Hiroki

2008-01-01

Purpose: To evaluate the three-dimensional intrafraction motion of the breast during tangential breast irradiation using a real-time tracking radiotherapy (RT) system with a high-sampling frequency. Methods and Materials: A total of 17 patients with breast cancer who had received breast conservation RT were included in this study. A 2.0-mm gold marker was placed on the skin near the nipple of the breast for RT. A fluoroscopic real-time tumor-tracking RT system was used to monitor the marker. The range of motion of each patient was calculated in three directions. Results: The mean ± standard deviation of the range of respiratory motion was 1.0 ± 0.6 mm (median, 0.9; 95% confidence interval [CI] of the marker position, 0.4-2.6), 1.3 ± 0.5 mm (median, 1.1; 95% CI, 0.5-2.5), and 2.6 ± 1.4 (median, 2.3; 95% CI, 1.0-6.9) for the right-left, craniocaudal, and anteroposterior direction, respectively. No correlation was found between the range of motion and the body mass index or respiratory function. The mean ± standard deviation of the absolute value of the baseline shift in the right-left, craniocaudal, and anteroposterior direction was 0.2 ± 0.2 mm (range, 0.0-0.8 mm), 0.3 ± 0.2 mm (range, 0.0-0.7 mm), and 0.8 ± 0.7 mm (range, 0.1-1.8 mm), respectively. Conclusion: Both the range of motion and the baseline shift were within a few millimeters in each direction. As long as the conventional wedge-pair technique and the proper immobilization are used, the intrafraction three-dimensional change in the breast surface did not much influence the dose distribution

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

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

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

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.

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.

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)

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.

Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition

Directory of Open Access Journals (Sweden)

Fu-Tai Wang

2015-07-01

Full Text Available Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD can decompose a signal into several intrinsic mode functions (IMFs that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method.

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

Hyperventilation in a motion sickness desensitization program

NARCIS (Netherlands)

Mert, A.; Bles, W.; Nooij, S.A.E.

2007-01-01

Introduction: In motion sickness desensitization programs, the motion sickness provocative stimulus is often a forward bending of the trunk on a rotating chair, inducing Coriolis effects. Since respiratory relaxation techniques are applied successfully in these courses, we investigated whether these

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)

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.

Analysis of Lung Tumor Motion in a Large Sample: Patterns and Factors Influencing Precise Delineation of Internal Target Volume

Energy Technology Data Exchange (ETDEWEB)

Knybel, Lukas [Department of Oncology, University Hospital Ostrava, Ostrava (Czech Republic); VŠB-Technical University of Ostrava, Ostrava (Czech Republic); Cvek, Jakub, E-mail: Jakub.cvek@fno.cz [Department of Oncology, University Hospital Ostrava, Ostrava (Czech Republic); Molenda, Lukas; Stieberova, Natalie; Feltl, David [Department of Oncology, University Hospital Ostrava, Ostrava (Czech Republic)

2016-11-15

Purpose/Objective: To evaluate lung tumor motion during respiration and to describe factors affecting the range and variability of motion in patients treated with stereotactic ablative radiation therapy. Methods and Materials: Log file analysis from online respiratory tumor tracking was performed in 145 patients. Geometric tumor location in the lungs, tumor volume and origin (primary or metastatic), sex, and tumor motion amplitudes in the superior-inferior (SI), latero-lateral (LL), and anterior-posterior (AP) directions were recorded. Tumor motion variability during treatment was described using intrafraction/interfraction amplitude variability and tumor motion baseline changes. Tumor movement dependent on the tumor volume, position and origin, and sex were evaluated using statistical regression and correlation analysis. Results: After analysis of >500 hours of data, the highest rates of motion amplitudes, intrafraction/interfraction variation, and tumor baseline changes were in the SI direction (6.0 ± 2.2 mm, 2.2 ± 1.8 mm, 1.1 ± 0.9 mm, and −0.1 ± 2.6 mm). The mean motion amplitudes in the lower/upper geometric halves of the lungs were significantly different (P<.001). Motion amplitudes >15 mm were observed only in the lower geometric quarter of the lungs. Higher tumor motion amplitudes generated higher intrafraction variations (R=.86, P<.001). Interfraction variations and baseline changes >3 mm indicated tumors contacting mediastinal structures or parietal pleura. On univariate analysis, neither sex nor tumor origin (primary vs metastatic) was an independent predictive factor of different movement patterns. Metastatic lesions in women, but not men, showed significantly higher mean amplitudes (P=.03) and variability (primary, 2.7 mm; metastatic, 4.9 mm; P=.002) than primary tumors. Conclusion: Online tracking showed significant irregularities in lung tumor movement during respiration. Motion amplitude was significantly lower in upper lobe

SU-D-207A-07: The Effects of Inter-Cycle Respiratory Motion Variation On Dose Accumulation in Single Fraction MR-Guided SBRT Treatment of Renal Cell Carcinoma

Energy Technology Data Exchange (ETDEWEB)

Stemkens, B; Glitzner, M; Kontaxis, C; Prins, F; Crijns, SPM; Kerkmeijer, L; Lagendijk, J; Berg, CAT van den; Tijssen, RHN [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands); Denis de Senneville, B [Imaging Division, University Medical Center Utrecht, Utrecht (Netherlands); IMB, UMR 5251 CNRS/University of Bordeaux (France)

2016-06-15

Purpose: To assess the dose deposition in simulated single-fraction MR-Linac treatments of renal cell carcinoma, when inter-cycle respiratory motion variation is taken into account using online MRI. Methods: Three motion characterization methods, with increasing complexity, were compared to evaluate the effect of inter-cycle motion variation and drifts on the accumulated dose for an SBRT kidney MR-Linac treatment: 1) STATIC, in which static anatomy was assumed, 2) AVG-RESP, in which 4D-MRI phase-volumes were time-weighted, based on the respiratory phase and 3) PCA, in which 3D volumes were generated using a PCA-model, enabling the detection of inter-cycle variations and drifts. An experimental ITV-based kidney treatment was simulated in a 1.5T magnetic field on three volunteer datasets. For each volunteer a retrospectively sorted 4D-MRI (ten respiratory phases) and fast 2D cine-MR images (temporal resolution = 476ms) were acquired to simulate MR-imaging during radiation. For each method, the high spatio-temporal resolution 3D volumes were non-rigidly registered to obtain deformation vector fields (DVFs). Using the DVFs, pseudo-CTs (generated from the 4D-MRI) were deformed and the dose was accumulated for the entire treatment. The accuracies of all methods were independently determined using an additional, orthogonal 2D-MRI slice. Results: Motion was most accurately estimated using the PCA method, which correctly estimated drifts and inter-cycle variations (RMSE=3.2, 2.2, 1.1mm on average for STATIC, AVG-RESP and PCA, compared to the 2DMRI slice). Dose-volume parameters on the ITV showed moderate changes (D99=35.2, 32.5, 33.8Gy for STATIC, AVG-RESP and PCA). AVG-RESP showed distinct hot/cold spots outside the ITV margin, which were more distributed for the PCA scenario, since inter-cycle variations were not modeled by the AVG-RESP method. Conclusion: Dose differences were observed when inter-cycle variations were taken into account. The increased inter

Mitigation of motion artifacts in CBCT of lung tumors based on tracked tumor motion during CBCT acquisition

International Nuclear Information System (INIS)

Lewis, John H; Li Ruijiang; Jia Xun; Watkins, W Tyler; Song, William Y; Jiang, Steve B; Lou, Yifei

2011-01-01

An algorithm capable of mitigating respiratory motion blurring artifacts in cone-beam computed tomography (CBCT) lung tumor images based on the motion of the tumor during the CBCT scan is developed. The tumor motion trajectory and probability density function (PDF) are reconstructed from the acquired CBCT projection images using a recently developed algorithm Lewis et al (2010 Phys. Med. Biol. 55 2505-22). Assuming that the effects of motion blurring can be represented by convolution of the static lung (or tumor) anatomy with the motion PDF, a cost function is defined, consisting of a data fidelity term and a total variation regularization term. Deconvolution is performed through iterative minimization of this cost function. The algorithm was tested on digital respiratory phantom, physical respiratory phantom and patient data. A clear qualitative improvement is evident in the deblurred images as compared to the motion-blurred images for all cases. Line profiles show that the tumor boundaries are more accurately and clearly represented in the deblurred images. The normalized root-mean-squared error between the images used as ground truth and the motion-blurred images are 0.29, 0.12 and 0.30 in the digital phantom, physical phantom and patient data, respectively. Deblurring reduces the corresponding values to 0.13, 0.07 and 0.19. Application of a -700 HU threshold to the digital phantom results in tumor dimension measurements along the superior-inferior axis of 2.8, 1.8 and 1.9 cm in the motion-blurred, ground truth and deblurred images, respectively. Corresponding values for the physical phantom are 3.4, 2.7 and 2.7 cm. A threshold of -500 HU applied to the patient case gives measurements of 3.1, 1.6 and 1.7 cm along the SI axis in the CBCT, 4DCT and deblurred images, respectively. This technique could provide more accurate information about a lung tumor's size and shape on the day of treatment.

Verification of motion induced thread effect during tomotherapy using gel dosimetry

International Nuclear Information System (INIS)

Edvardsson, Anneli; Ljusberg, Anna; Ceberg, Crister; Medin, Joakim; Ambolt, Lee; Nordström, Fredrik; Ceberg, Sofie

2015-01-01

The purpose of the study was to evaluate how breathing motion during tomotherapy (Accuray, CA, USA) treatment affects the absorbed dose distribution. The experiments were carried out using gel dosimetry and a motion device simulating respiratory-like motion (HexaMotion, ScandiDos, Uppsala, Sweden). Normoxic polyacrylamide gels (nPAG) were irradiated, both during respiratory-like motion and in a static mode. To be able to investigate interplay effects the static absorbed dose distribution was convolved with the motion function and differences between the dynamic and convolved static absorbed dose distributions were interpreted as interplay effects. The expected dose blurring was present and the interplay effects formed a spiral pattern in the lower dose volume. This was expected since the motion induced affects the preset pitch and the theoretically predicted thread effect may emerge. In this study, the motion induced thread effect was experimentally verified for the first time

Motion correction options in PET/MRI.

Science.gov (United States)

Catana, Ciprian

2015-05-01

Subject motion is unavoidable in clinical and research imaging studies. Breathing is the most important source of motion in whole-body PET and MRI studies, affecting not only thoracic organs but also those in the upper and even lower abdomen. The motion related to the pumping action of the heart is obviously relevant in high-resolution cardiac studies. These two sources of motion are periodic and predictable, at least to a first approximation, which means certain techniques can be used to control the motion (eg, by acquiring the data when the organ of interest is relatively at rest). Additionally, nonperiodic and unpredictable motion can also occur during the scan. One obvious limitation of methods relying on external devices (eg, respiratory bellows or the electrocardiogram signal to monitor the respiratory or cardiac cycle, respectively) to trigger or gate the data acquisition is that the complex motion of internal organs cannot be fully characterized. However, detailed information can be obtained using either the PET or MRI data (or both) allowing the more complete characterization of the motion field so that a motion model can be built. Such a model and the information derived from simple external devices can be used to minimize the effects of motion on the collected data. In the ideal case, all the events recorded during the PET scan would be used to generate a motion-free or corrected PET image. The detailed motion field can be used for this purpose by applying it to the PET data before, during, or after the image reconstruction. Integrating all these methods for motion control, characterization, and correction into a workflow that can be used for routine clinical studies is challenging but could potentially be extremely valuable given the improvement in image quality and reduction of motion-related image artifacts. Copyright © 2015 Elsevier Inc. All rights reserved.

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...

Estimating actigraphy from motion artifacts in ECG and respiratory effort signals.

Science.gov (United States)

Fonseca, Pedro; Aarts, Ronald M; Long, Xi; Rolink, Jérôme; Leonhardt, Steffen

2016-01-01

Recent work in unobtrusive sleep/wake classification has shown that cardiac and respiratory features can help improve classification performance. Nevertheless, actigraphy remains the single most discriminative modality for this task. Unfortunately, it requires the use of dedicated devices in addition to the sensors used to measure electrocardiogram (ECG) or respiratory effort. This paper proposes a method to estimate actigraphy from the body movement artifacts present in the ECG and respiratory inductance plethysmography (RIP) based on the time-frequency analysis of those signals. Using a continuous wavelet transform to analyze RIP, and ECG and RIP combined, it provides a surrogate measure of actigraphy with moderate correlation (for ECG+RIP, ρ = 0.74, p  <  0.001) and agreement (mean bias ratio of 0.94 and 95% agreement ratios of 0.11 and 8.45) with reference actigraphy. More important, it can be used as a replacement of actigraphy in sleep/wake classification: after cross-validation with a data set comprising polysomnographic (PSG) recordings of 15 healthy subjects and 25 insomniacs annotated by an external sleep technician, it achieves a statistically non-inferior classification performance when used together with respiratory features (average κ of 0.64 for 15 healthy subjects, and 0.50 for a dataset with 40 healthy and insomniac subjects), and when used together with respiratory and cardiac features (average κ of 0.66 for 15 healthy subjects, and 0.56 for 40 healthy and insomniac subjects). Since this method eliminates the need for a dedicated actigraphy device, it reduces the number of sensors needed for sleep/wake classification to a single sensor when using respiratory features, and to two sensors when using respiratory and cardiac features without any loss in performance. It offers a major benefit in terms of comfort for long-term home monitoring and is immediately applicable for legacy ECG and RIP monitoring devices already used in clinical

SU-D-207A-05: Investigating Sparse-Sampled MRI for Motion Management in Thoracic Radiotherapy

International Nuclear Information System (INIS)

Sabouri, P; Sawant, A; Arai, T

2016-01-01

Purpose: Sparse sampling and reconstruction-based MRI techniques represent an attractive strategy to achieve sufficiently high image acquisition speed while maintaining image quality for the task of radiotherapy guidance. In this study, we examine rapid dynamic MRI using a sparse sampling sequence k-t BLAST in capturing motion-induced, cycle-to-cycle variations in tumor position. We investigate the utility of long-term MRI-based motion monitoring as a means of better characterizing respiration-induced tumor motion compared to a single-cycle 4DCT. Methods: An MRI-compatible, programmable, deformable lung motion phantom with eleven 1.5 ml water marker tubes was placed inside a 3.0 T whole-body MR scanner (Philips Ingenia). The phantom was programmed with 10 lung tumor motion traces previously recorded using the Synchrony system. 2D+t image sequences of a coronal slice were acquired using a balanced-SSFP sequence combined with k-t BLAST (accn=3, resolution=0.66×0.66×5 mm3; acquisition time = 110 ms/slice). kV fluoroscopic (ground truth) and 4DCT imaging was performed with the same phantom setup and motion trajectories. Marker positions in all three modalities were segmented and tracked using an opensource deformable image registration package, NiftyReg. Results: Marker trajectories obtained from rapid MRI exhibited <1 mm error compared to kv Fluoro trajectories in the presence of complex motion including baseline shifts and changes in respiratory amplitude, indicating the ability of MRI to monitor motion with adequate geometric fidelity for the purpose of radiotherapy guidance. In contrast, the trajectory derived from 4DCT exhibited significant errors up to 6 mm due to cycle-to-cycle variations and baseline shifts. Consequently, 4DCT was found to underestimate the range of marker motion by as much as 50%. Conclusion: Dynamic MRI is a promising tool for radiotherapy motion management as it permits for longterm, dose-free, soft-tissue-based monitoring of motion

SU-D-207A-05: Investigating Sparse-Sampled MRI for Motion Management in Thoracic Radiotherapy

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Sabouri, P; Sawant, A [University of Maryland School of Medicine, Baltimore, MD (United States); Arai, T [University of Texas Southwestern Medical Center, Dallas, TX (United States)

2016-06-15

Purpose: Sparse sampling and reconstruction-based MRI techniques represent an attractive strategy to achieve sufficiently high image acquisition speed while maintaining image quality for the task of radiotherapy guidance. In this study, we examine rapid dynamic MRI using a sparse sampling sequence k-t BLAST in capturing motion-induced, cycle-to-cycle variations in tumor position. We investigate the utility of long-term MRI-based motion monitoring as a means of better characterizing respiration-induced tumor motion compared to a single-cycle 4DCT. Methods: An MRI-compatible, programmable, deformable lung motion phantom with eleven 1.5 ml water marker tubes was placed inside a 3.0 T whole-body MR scanner (Philips Ingenia). The phantom was programmed with 10 lung tumor motion traces previously recorded using the Synchrony system. 2D+t image sequences of a coronal slice were acquired using a balanced-SSFP sequence combined with k-t BLAST (accn=3, resolution=0.66×0.66×5 mm3; acquisition time = 110 ms/slice). kV fluoroscopic (ground truth) and 4DCT imaging was performed with the same phantom setup and motion trajectories. Marker positions in all three modalities were segmented and tracked using an opensource deformable image registration package, NiftyReg. Results: Marker trajectories obtained from rapid MRI exhibited <1 mm error compared to kv Fluoro trajectories in the presence of complex motion including baseline shifts and changes in respiratory amplitude, indicating the ability of MRI to monitor motion with adequate geometric fidelity for the purpose of radiotherapy guidance. In contrast, the trajectory derived from 4DCT exhibited significant errors up to 6 mm due to cycle-to-cycle variations and baseline shifts. Consequently, 4DCT was found to underestimate the range of marker motion by as much as 50%. Conclusion: Dynamic MRI is a promising tool for radiotherapy motion management as it permits for longterm, dose-free, soft-tissue-based monitoring of motion

Fractal ventilation enhances respiratory sinus arrhythmia

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Girling Linda G

2005-05-01

Full Text Available Abstract Background Programming a mechanical ventilator with a biologically variable or fractal breathing pattern (an example of 1/f noise improves gas exchange and respiratory mechanics. Here we show that fractal ventilation increases respiratory sinus arrhythmia (RSA – a mechanism known to improve ventilation/perfusion matching. Methods Pigs were anaesthetised with propofol/ketamine, paralysed with doxacurium, and ventilated in either control mode (CV or in fractal mode (FV at baseline and then following infusion of oleic acid to result in lung injury. Results Mean RSA and mean positive RSA were nearly double with FV, both at baseline and following oleic acid. At baseline, mean RSA = 18.6 msec with CV and 36.8 msec with FV (n = 10; p = 0.043; post oleic acid, mean RSA = 11.1 msec with CV and 21.8 msec with FV (n = 9, p = 0.028; at baseline, mean positive RSA = 20.8 msec with CV and 38.1 msec with FV (p = 0.047; post oleic acid, mean positive RSA = 13.2 msec with CV and 24.4 msec with FV (p = 0.026. Heart rate variability was also greater with FV. At baseline the coefficient of variation for heart rate was 2.2% during CV and 4.0% during FV. Following oleic acid the variation was 2.1 vs. 5.6% respectively. Conclusion These findings suggest FV enhances physiological entrainment between respiratory, brain stem and cardiac nonlinear oscillators, further supporting the concept that RSA itself reflects cardiorespiratory interaction. In addition, these results provide another mechanism whereby FV may be superior to conventional CV.

Non-invasive measure of respiratory mechanics and conventional respiratory parameters in conscious large animals by high frequency Airwave Oscillometry.

Science.gov (United States)

Bassett, Leanne; Troncy, Eric; Robichaud, Annette; Schuessler, Thomas F; Pouliot, Mylène; Ascah, Alexis; Authier, Simon

2014-01-01

A number of drugs in clinical trials are discontinued due to potentially life-threatening airway obstruction. As some drugs may not cause changes in core battery parameters such as tidal volume (Vt), respiratory rate (RR) or minute ventilation (MV), including measurements of respiratory mechanics in safety pharmacology studies represents an opportunity for design refinement. The present study aimed to test a novel non-invasive methodology to concomitantly measure respiratory system resistance (Rrs) and conventional respiratory parameters (Vt, RR, MV) in conscious Beagle dogs and cynomolgus monkeys. An Airwave Oscillometry system (tremoFlo; THORASYS Inc., Montreal, Canada) was used to concomitantly assess Rrs and conventional respiratory parameters before and after intravenous treatment with a bronchoactive agent. Respiratory mechanics measurements were performed by applying a short (i.e. 16s) single high frequency (19Hz) waveform at the subject's airway opening via a face mask. During measurements, pressure and flow signals were recorded. After collection of baseline measurements, methacholine was administered intravenously to Beagle dogs (n=6) and cynomolgus monkeys (n=4) at 8 and 68μg/kg, respectively. In dogs, methacholine induced significant increases in Vt, RR and MV while in monkeys, it only augmented RR. A significant increase in Rrs was observed after methacholine administration in both species with mean percentage peak increases from baseline of 88 (53)% for dogs and 28 (16)% for cynomolgus monkeys. Airwave Oscillometry appears to be a promising non-invasive methodology to enable respiratory mechanics measurements in conscious large animals, a valuable refinement in respiratory safety pharmacology. Copyright © 2014 Elsevier Inc. All rights reserved.

High performance MRI simulations of motion on multi-GPU systems.

Science.gov (United States)

Xanthis, Christos G; Venetis, Ioannis E; Aletras, Anthony H

2014-07-04

MRI physics simulators have been developed in the past for optimizing imaging protocols and for training purposes. However, these simulators have only addressed motion within a limited scope. The purpose of this study was the incorporation of realistic motion, such as cardiac motion, respiratory motion and flow, within MRI simulations in a high performance multi-GPU environment. Three different motion models were introduced in the Magnetic Resonance Imaging SIMULator (MRISIMUL) of this study: cardiac motion, respiratory motion and flow. Simulation of a simple Gradient Echo pulse sequence and a CINE pulse sequence on the corresponding anatomical model was performed. Myocardial tagging was also investigated. In pulse sequence design, software crushers were introduced to accommodate the long execution times in order to avoid spurious echoes formation. The displacement of the anatomical model isochromats was calculated within the Graphics Processing Unit (GPU) kernel for every timestep of the pulse sequence. Experiments that would allow simulation of custom anatomical and motion models were also performed. Last, simulations of motion with MRISIMUL on single-node and multi-node multi-GPU systems were examined. Gradient Echo and CINE images of the three motion models were produced and motion-related artifacts were demonstrated. The temporal evolution of the contractility of the heart was presented through the application of myocardial tagging. Better simulation performance and image quality were presented through the introduction of software crushers without the need to further increase the computational load and GPU resources. Last, MRISIMUL demonstrated an almost linear scalable performance with the increasing number of available GPU cards, in both single-node and multi-node multi-GPU computer systems. MRISIMUL is the first MR physics simulator to have implemented motion with a 3D large computational load on a single computer multi-GPU configuration. The incorporation

SU-F-J-136: Impact of Audiovisual Biofeedback On Interfraction Motion Over a Course of Liver Cancer Stereotactic Body Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Pollock, S [Radiation Physics Laboratory, Sydney (Australia); Tse, R; Martin, D; McLean, L; Pham, M; Tait, D; Estoesta, R; Whittington, G; Turley, J; Kearney, C; Cho, G; Pickard, S; Aston, P [Chris OBrien Lifehouse, Sydney, NSW (Australia); Hill, R [Chris OBrien Lifehouse Camperdown (Australia); Makhija, K [University of Sydney, Camperdown, NSW (Australia); O’Brien, R; Keall, P [University of Sydney, Sydney, NSW (Australia)

2016-06-15

Purpose: In abdominal radiotherapy inconsistent interfraction respiratory motion can result in deviations during treatment from what was planned in terms of target position and motion. Audiovisual biofeedback (AVB) is an interactive respiratory guide that produces a guiding interface that the patient follows over a course of radiotherapy to facilitate regular respiratory motion. This study assessed the impact of AVB on interfraction motion consistency over a course of liver cancer SBRT. Methods: Five liver cancer patients have been recruited into this study, 3 followed AVB over their course of SBRT and 2 were free breathing (FB). Respiratory signals from the Varian RPM were obtained during 4DCT and each treatment fraction. Respiratory signals were organized into 10 respiratory bins, and interfraction consistency was quantified by the difference between each treatment fraction respiratory bin and each respiratory bin from 4DCT. Interfraction consistency was considered as both the relative difference (as a percentage) and absolute difference (in centimeters) between treatment respiratory bins and 4DCT respiratory bins. Results: The relative difference between 4DCT and treatment respiratory bins was 22 ± 16% for FB, and 15 ± 10% for AVB, an improvement of 32% (p < 0.001) with AVB. The absolute difference between 4DCT and treatment respiratory bins was 0.15 ± 0.10 cm for FB, and 0.14 ± 0.13 cm for AVB, an improvement of 4% (p = 0.6) with AVB. Conclusion: This was the first study to compare the impact of AVB breathing guidance on interfraction motion consistency over a course of radiotherapy. AVB demonstrated to significantly reduce the relative difference between 4DCT and treatment respiratory motion, but the absolute differences were comparable, largely due to one AVB patient exhibiting a larger amplitude than the other patients. This study demonstrates the potential benefit of AVB in reducing motion variations during treatment from what was planned. Paul Keall

SU-F-J-136: Impact of Audiovisual Biofeedback On Interfraction Motion Over a Course of Liver Cancer Stereotactic Body Radiotherapy

International Nuclear Information System (INIS)

Pollock, S; Tse, R; Martin, D; McLean, L; Pham, M; Tait, D; Estoesta, R; Whittington, G; Turley, J; Kearney, C; Cho, G; Pickard, S; Aston, P; Hill, R; Makhija, K; O’Brien, R; Keall, P

2016-01-01

Purpose: In abdominal radiotherapy inconsistent interfraction respiratory motion can result in deviations during treatment from what was planned in terms of target position and motion. Audiovisual biofeedback (AVB) is an interactive respiratory guide that produces a guiding interface that the patient follows over a course of radiotherapy to facilitate regular respiratory motion. This study assessed the impact of AVB on interfraction motion consistency over a course of liver cancer SBRT. Methods: Five liver cancer patients have been recruited into this study, 3 followed AVB over their course of SBRT and 2 were free breathing (FB). Respiratory signals from the Varian RPM were obtained during 4DCT and each treatment fraction. Respiratory signals were organized into 10 respiratory bins, and interfraction consistency was quantified by the difference between each treatment fraction respiratory bin and each respiratory bin from 4DCT. Interfraction consistency was considered as both the relative difference (as a percentage) and absolute difference (in centimeters) between treatment respiratory bins and 4DCT respiratory bins. Results: The relative difference between 4DCT and treatment respiratory bins was 22 ± 16% for FB, and 15 ± 10% for AVB, an improvement of 32% (p < 0.001) with AVB. The absolute difference between 4DCT and treatment respiratory bins was 0.15 ± 0.10 cm for FB, and 0.14 ± 0.13 cm for AVB, an improvement of 4% (p = 0.6) with AVB. Conclusion: This was the first study to compare the impact of AVB breathing guidance on interfraction motion consistency over a course of radiotherapy. AVB demonstrated to significantly reduce the relative difference between 4DCT and treatment respiratory motion, but the absolute differences were comparable, largely due to one AVB patient exhibiting a larger amplitude than the other patients. This study demonstrates the potential benefit of AVB in reducing motion variations during treatment from what was planned. Paul Keall

SU-F-J-117: Impact of Motion Artifacts On Image Quality and Accuracy of Tumor Motion Reconstruction in 4D CT-On-Rails and MV-CBCT Scans: A Phantom Study

Energy Technology Data Exchange (ETDEWEB)

Lin, T; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States)

2016-06-15

Purpose: To compare and quantify respiratory motion artifacts in images from free breathing 4D-CT-on-Rails(CTOR) and those from MV-Cone-beam-CT(MVCB) and facilitate respiratory motion guided radiation therapy. Methods: 4D-CTOR: Siemens Somatom CT-on-Rails system with Anzai belt loaded with pressure sensor load cells. 4D scans were performed in helical mode, pitch 0.1, gantry rotation time 0.5s, 1.5mm slice thickness, 120kVp, 400 mAs. Normal and fast breathing (>12rpm) scanning protocols were investigated. Helical scan, AIP(average intensity projection) and MIP(maximum intensity projection) were generated from 4D-CTOR scans with amplitude sorting into 10 phases.MVCB: Siemens Artiste diamond view(1MV)MVCB was performed with 5MU thorax protocol with 60 second of full rotation.Phantom: Anzai AZ-733V respiratory phantom. The settings were set to normal and resp. modes with repetition rates at 15 rpm and 10 rpm. Surgical clips, acrylic, wooden, rubber and lung density, total six mock-ups were scanned and compared in this study.Signal-to-noise ratio(SNR), contrast-to-noise ratio(CNR) and reconstructed motion volume were compared to different respiratory setups for the mock-ups. Results: Reconstructed motion volume was compared to the real object volume for the six test mock-ups. It shows that free breathing helical in all instances underestimates the object excursions largest to −67.4% and least −6.3%. Under normal breathing settings, MIP can predict very precise motion volume with minimum 0.4% and largest −13.9%. MVCB shows underestimate of the motion volume with −1.11% minimum and −18.0% maximum. With fast breathing, AIP provides bad representation of the object motion; however, the MIP can predict the motion volume with −2.0% to −11.4% underestimate. Conclusion: Respiratory motion guided radiation therapy requires good motion recording. This study shows that regular CTOR helical scans provides bad guidance, 4D CTOR AIP cannot represent the fast breathing

Motion of the esophagus due to cardiac motion.

Directory of Open Access Journals (Sweden)

Jacob Palmer

Full Text Available When imaging studies (e.g. CT are used to quantify morphological changes in an anatomical structure, it is necessary to understand the extent and source of motion which can give imaging artifacts (e.g. blurring or local distortion. The objective of this study was to assess the magnitude of esophageal motion due to cardiac motion. We used retrospective electrocardiogram-gated contrast-enhanced computed tomography angiography images for this study. The anatomic region from the carina to the bottom of the heart was taken at deep-inspiration breath hold with the patients' arms raised above their shoulders, in a position similar to that used for radiation therapy. The esophagus was delineated on the diastolic phase of cardiac motion, and deformable registration was used to sequentially deform the images in nearest-neighbor phases among the 10 cardiac phases, starting from the diastolic phase. Using the 10 deformation fields generated from the deformable registration, the magnitude of the extreme displacements was then calculated for each voxel, and the mean and maximum displacement was calculated for each computed tomography slice for each patient. The average maximum esophageal displacement due to cardiac motion for all patients was 5.8 mm (standard deviation: 1.6 mm, maximum: 10.0 mm in the transverse direction. For 21 of 26 patients, the largest esophageal motion was found in the inferior region of the heart; for the other patients, esophageal motion was approximately independent of superior-inferior position. The esophagus motion was larger at cardiac phases where the electrocardiogram R-wave occurs. In conclusion, the magnitude of esophageal motion near the heart due to cardiac motion is similar to that due to other sources of motion, including respiratory motion and intra-fraction motion. A larger cardiac motion will result into larger esophagus motion in a cardiac cycle.

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

Breath-holding times in various phases of respiration and effect of respiratory training in lung cancer patients.

Science.gov (United States)

Tibdewal, Anil; Munshi, Anusheel; Pathak, Rima; Misra, Shagun; Daptardar, Anuradha; Singh, Vincent; Agarwal, Jai Prakash

2015-08-01

Breath-holding (BH) technique is used for reducing the intrafraction-tumour motion in mobile lung tumours treated with radiotherapy (RT). There is paucity of literature evaluating differences in BH times in various phases of respiration in patients with lung cancer. One hundred consecutive patients with lung cancer planned for radical RT/chemoradiation were accrued in the study. Eighty-seven patients were eligible for analysis at RT conclusion. Baseline pulmonary function test (PFT) were performed in all patients, and respiratory training was given from the day of RT planning. Deep inspiration breath hold (DIBH), deep expiration breath hold (DEBH) and mid-ventilation breath hold (MVBH) were recorded manually with a stopwatch for each patient at four time points (RT planning/baseline, RT starting, during RT and RT conclusion). Median DIBH times at RT planning, RT starting, during RT and RT conclusion were 21.2, 20.6, 20.1 and 21.1 s, respectively. The corresponding median DEBH and MVBH times were 16.3, 18.2, 18.3, 18.5 s and 19.9, 20.5, 21.3, 22.1 s, respectively. Respiratory training increased MVBH time at RT conclusion compared to baseline, which was statistically significant (19.9-22.1 s, P = 0.002). DIBH or DEBH times were stable at various time points with neither a significant improvement nor decline. Among various patient and tumour factors Forced Vital Capacity pre-bronchodilation (FVCpre ) was the only factor that consistently predicted DIBH, DEBH and MVBH at all four time points with P value phases of respiration. Respiratory training improved MVBH time while consistently maintaining DIBH and DEBH times throughout the course of radiotherapy. © 2015 The Royal Australian and New Zealand College of Radiologists.

SU-E-J-191: Motion Prediction Using Extreme Learning Machine in Image Guided Radiotherapy

International Nuclear Information System (INIS)

Jia, J; Cao, R; Pei, X; Wang, H; Hu, L

2015-01-01

Purpose: Real-time motion tracking is a critical issue in image guided radiotherapy due to the time latency caused by image processing and system response. It is of great necessity to fast and accurately predict the future position of the respiratory motion and the tumor location. Methods: The prediction of respiratory position was done based on the positioning and tracking module in ARTS-IGRT system which was developed by FDS Team (www.fds.org.cn). An approach involving with the extreme learning machine (ELM) was adopted to predict the future respiratory position as well as the tumor’s location by training the past trajectories. For the training process, a feed-forward neural network with one single hidden layer was used for the learning. First, the number of hidden nodes was figured out for the single layered feed forward network (SLFN). Then the input weights and hidden layer biases of the SLFN were randomly assigned to calculate the hidden neuron output matrix. Finally, the predicted movement were obtained by applying the output weights and compared with the actual movement. Breathing movement acquired from the external infrared markers was used to test the prediction accuracy. And the implanted marker movement for the prostate cancer was used to test the implementation of the tumor motion prediction. Results: The accuracy of the predicted motion and the actual motion was tested. Five volunteers with different breathing patterns were tested. The average prediction time was 0.281s. And the standard deviation of prediction accuracy was 0.002 for the respiratory motion and 0.001 for the tumor motion. Conclusion: The extreme learning machine method can provide an accurate and fast prediction of the respiratory motion and the tumor location and therefore can meet the requirements of real-time tumor-tracking in image guided radiotherapy

SU-E-J-191: Motion Prediction Using Extreme Learning Machine in Image Guided Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Jia, J; Cao, R; Pei, X; Wang, H; Hu, L [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Engineering Technology Research Center of Accurate Radiotherapy of Anhui Province, Hefei 230031 (China); Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, SuZhou (China)

2015-06-15

Purpose: Real-time motion tracking is a critical issue in image guided radiotherapy due to the time latency caused by image processing and system response. It is of great necessity to fast and accurately predict the future position of the respiratory motion and the tumor location. Methods: The prediction of respiratory position was done based on the positioning and tracking module in ARTS-IGRT system which was developed by FDS Team (www.fds.org.cn). An approach involving with the extreme learning machine (ELM) was adopted to predict the future respiratory position as well as the tumor’s location by training the past trajectories. For the training process, a feed-forward neural network with one single hidden layer was used for the learning. First, the number of hidden nodes was figured out for the single layered feed forward network (SLFN). Then the input weights and hidden layer biases of the SLFN were randomly assigned to calculate the hidden neuron output matrix. Finally, the predicted movement were obtained by applying the output weights and compared with the actual movement. Breathing movement acquired from the external infrared markers was used to test the prediction accuracy. And the implanted marker movement for the prostate cancer was used to test the implementation of the tumor motion prediction. Results: The accuracy of the predicted motion and the actual motion was tested. Five volunteers with different breathing patterns were tested. The average prediction time was 0.281s. And the standard deviation of prediction accuracy was 0.002 for the respiratory motion and 0.001 for the tumor motion. Conclusion: The extreme learning machine method can provide an accurate and fast prediction of the respiratory motion and the tumor location and therefore can meet the requirements of real-time tumor-tracking in image guided radiotherapy.

Extension of the NCAT phantom for the investigation of intra-fraction respiratory motion in IMRT using 4D Monte Carlo

International Nuclear Information System (INIS)

McGurk, Ross; Seco, Joao; Wolfgang, John; Paganetti, Harald; Riboldi, Marco; Segars, Paul

2010-01-01

The purpose of this work was to create a computational platform for studying motion in intensity modulated radiotherapy (IMRT). Specifically, the non-uniform rational B-spline (NURB) cardiac and torso (NCAT) phantom was modified for use in a four-dimensional Monte Carlo (4D-MC) simulation system to investigate the effect of respiratory-induced intra-fraction organ motion on IMRT dose distributions as a function of diaphragm motion, lesion size and lung density. Treatment plans for four clinical scenarios were designed: diaphragm peak-to-peak amplitude of 1 cm and 3 cm, and two lesion sizes-2 cm and 4 cm diameter placed in the lower lobe of the right lung. Lung density was changed for each phase using a conservation of mass calculation. Further, a new heterogeneous lung model was implemented and tested. Each lesion had an internal target volume (ITV) subsequently expanded by 15 mm isotropically to give the planning target volume (PTV). The PTV was prescribed to receive 72 Gy in 40 fractions. The MLC leaf sequence defined by the planning system for each patient was exported and used as input into the MC system. MC simulations using the dose planning method (DPM) code together with deformable image registration based on the NCAT deformation field were used to find a composite dose distribution for each phantom. These composite distributions were subsequently analyzed using information from the dose volume histograms (DVH). Lesion motion amplitude has the largest effect on the dose distribution. Tumor size was found to have a smaller effect and can be mitigated by ensuring the planning constraints are optimized for the tumor size. The use of a dynamic or heterogeneous lung density model over a respiratory cycle does not appear to be an important factor with a ≤ 0.6% change in the mean dose received by the ITV, PTV and right lung. The heterogeneous model increases the realism of the NCAT phantom and may provide more accurate simulations in radiation therapy

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

SU-F-I-58: Image Quality Comparisons of Different Motion Magnitudes and TR Values in MR-PET

International Nuclear Information System (INIS)

Patrick, J; Thompson, R; Tavallaei, M; Drangova, M; Stodilka, R; Gaede, S

2016-01-01

Purpose: The aim of this work is to evaluate the accuracy and sensitivity of a respiratory-triggered MR-PET protocol in detecting four different sized lesions at two different magnitudes of motion, with two different TR values, using a novel PET-MR-CT compatible respiratory motion phantom. Methods: The eight-compartment torso phantom was setup adjacent to the motion stage, which moved four spherical compartments (28, 22, 17, 10 mm diameter) in two separate (1 and 2 cm) linear motion profiles, simulating a 3.5 second respiratory cycle. Scans were acquired on a 3T MR-PET system (Biograph mMR; Siemens Medical Solutions, Germany). MR measurements were taken with: 1) Respiratory-triggered T2-weighted turbo spin echo (BLADE) sequence in coronal orientation, and 2) Real-time balanced steady-state gradient echo sequence (TrueFISP) in coronal and sagittal planes. PET was acquired simultaneously with MR. Sphere geometries and motion profiles were measured and compared with ground truths for T2 BLADE-TSE acquisitions and real time TrueFISP images. PET quantification and geometry measurements were taken using standardized uptake values, voxel intensity plots and were compared with known values, and examined alongside MR-based attenuation maps. Contrast and signal-to-noise ratios were also compared for each of the acquisitions as functions of motion range and TR. Results: Comparison of lesion diameters indicate the respiratory triggered T2 BLADE-TSE was able to maintain geometry within −2 mm for 1 cm motion for both TR values, and within −3.1 mm for TR = 2000 ms at 2 cm motion. Sphere measurements in respiratory triggered PET images were accurate within +/− 5 mm for both ranges of motion for 28, 22, and 17 mm diameter spheres. Conclusion: Hybrid MR-PET systems show promise in imaging lung cancer in non-compliant patients, with their ability to acquire both modalities simultaneously. However, MR-based attenuation maps are still susceptible to motion derived artifacts and

SU-F-I-58: Image Quality Comparisons of Different Motion Magnitudes and TR Values in MR-PET

Energy Technology Data Exchange (ETDEWEB)

Patrick, J; Thompson, R [Lawson Health Research Institute, London, Ontario (Canada); Tavallaei, M; Drangova, M [Robarts Research Institute, London, Canada, London, Ontario (Canada); Stodilka, R [Western University, Canada, London, Ontario (Canada); Gaede, S [London Regional Cancer Program, London, Ontario (Canada)

2016-06-15

Purpose: The aim of this work is to evaluate the accuracy and sensitivity of a respiratory-triggered MR-PET protocol in detecting four different sized lesions at two different magnitudes of motion, with two different TR values, using a novel PET-MR-CT compatible respiratory motion phantom. Methods: The eight-compartment torso phantom was setup adjacent to the motion stage, which moved four spherical compartments (28, 22, 17, 10 mm diameter) in two separate (1 and 2 cm) linear motion profiles, simulating a 3.5 second respiratory cycle. Scans were acquired on a 3T MR-PET system (Biograph mMR; Siemens Medical Solutions, Germany). MR measurements were taken with: 1) Respiratory-triggered T2-weighted turbo spin echo (BLADE) sequence in coronal orientation, and 2) Real-time balanced steady-state gradient echo sequence (TrueFISP) in coronal and sagittal planes. PET was acquired simultaneously with MR. Sphere geometries and motion profiles were measured and compared with ground truths for T2 BLADE-TSE acquisitions and real time TrueFISP images. PET quantification and geometry measurements were taken using standardized uptake values, voxel intensity plots and were compared with known values, and examined alongside MR-based attenuation maps. Contrast and signal-to-noise ratios were also compared for each of the acquisitions as functions of motion range and TR. Results: Comparison of lesion diameters indicate the respiratory triggered T2 BLADE-TSE was able to maintain geometry within −2 mm for 1 cm motion for both TR values, and within −3.1 mm for TR = 2000 ms at 2 cm motion. Sphere measurements in respiratory triggered PET images were accurate within +/− 5 mm for both ranges of motion for 28, 22, and 17 mm diameter spheres. Conclusion: Hybrid MR-PET systems show promise in imaging lung cancer in non-compliant patients, with their ability to acquire both modalities simultaneously. However, MR-based attenuation maps are still susceptible to motion derived artifacts and

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

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

Analysis of Lung Tumor Motion in a Large Sample: Patterns and Factors Influencing Precise Delineation of Internal Target Volume

International Nuclear Information System (INIS)

Knybel, Lukas; Cvek, Jakub; Molenda, Lukas; Stieberova, Natalie; Feltl, David

2016-01-01

Purpose/Objective: To evaluate lung tumor motion during respiration and to describe factors affecting the range and variability of motion in patients treated with stereotactic ablative radiation therapy. Methods and Materials: Log file analysis from online respiratory tumor tracking was performed in 145 patients. Geometric tumor location in the lungs, tumor volume and origin (primary or metastatic), sex, and tumor motion amplitudes in the superior-inferior (SI), latero-lateral (LL), and anterior-posterior (AP) directions were recorded. Tumor motion variability during treatment was described using intrafraction/interfraction amplitude variability and tumor motion baseline changes. Tumor movement dependent on the tumor volume, position and origin, and sex were evaluated using statistical regression and correlation analysis. Results: After analysis of >500 hours of data, the highest rates of motion amplitudes, intrafraction/interfraction variation, and tumor baseline changes were in the SI direction (6.0 ± 2.2 mm, 2.2 ± 1.8 mm, 1.1 ± 0.9 mm, and −0.1 ± 2.6 mm). The mean motion amplitudes in the lower/upper geometric halves of the lungs were significantly different (P 15 mm were observed only in the lower geometric quarter of the lungs. Higher tumor motion amplitudes generated higher intrafraction variations (R=.86, P 3 mm indicated tumors contacting mediastinal structures or parietal pleura. On univariate analysis, neither sex nor tumor origin (primary vs metastatic) was an independent predictive factor of different movement patterns. Metastatic lesions in women, but not men, showed significantly higher mean amplitudes (P=.03) and variability (primary, 2.7 mm; metastatic, 4.9 mm; P=.002) than primary tumors. Conclusion: Online tracking showed significant irregularities in lung tumor movement during respiration. Motion amplitude was significantly lower in upper lobe tumors; higher interfraction amplitude variability indicated tumors in contact

XD-GRASP: Golden-angle radial MRI with reconstruction of extra motion-state dimensions using compressed sensing.

Science.gov (United States)

Feng, Li; Axel, Leon; Chandarana, Hersh; Block, Kai Tobias; Sodickson, Daniel K; Otazo, Ricardo

2016-02-01

To develop a novel framework for free-breathing MRI called XD-GRASP, which sorts dynamic data into extra motion-state dimensions using the self-navigation properties of radial imaging and reconstructs the multidimensional dataset using compressed sensing. Radial k-space data are continuously acquired using the golden-angle sampling scheme and sorted into multiple motion-states based on respiratory and/or cardiac motion signals derived directly from the data. The resulting undersampled multidimensional dataset is reconstructed using a compressed sensing approach that exploits sparsity along the new dynamic dimensions. The performance of XD-GRASP is demonstrated for free-breathing three-dimensional (3D) abdominal imaging, two-dimensional (2D) cardiac cine imaging and 3D dynamic contrast-enhanced (DCE) MRI of the liver, comparing against reconstructions without motion sorting in both healthy volunteers and patients. XD-GRASP separates respiratory motion from cardiac motion in cardiac imaging, and respiratory motion from contrast enhancement in liver DCE-MRI, which improves image quality and reduces motion-blurring artifacts. XD-GRASP represents a new use of sparsity for motion compensation and a novel way to handle motions in the context of a continuous acquisition paradigm. Instead of removing or correcting motion, extra motion-state dimensions are reconstructed, which improves image quality and also offers new physiological information of potential clinical value. © 2015 Wiley Periodicals, Inc.

Early return to baseline range of motion and strength after anterior shoulder instability surgery: a Multicenter Orthopaedic Outcomes Network (MOON) shoulder group cohort study.

Science.gov (United States)

Buckwalter V, Joseph A; Wolf, Brian R; Glass, Natalie; Bollier, Matt; Kuhn, John E; Hettrich, Carolyn M

2018-03-23

Patients often return to higher-level activities and sports at 4 to 8 months after anterior shoulder stabilization procedures. It is unknown what percentage of patients have regained normal function at this time frame and what factors predict residual deficits, range of motion (ROM), and strength after anterior shoulder instability surgery. Ten participating sites throughout the United States enrolled patients in a prospective cohort study including primary, revision, arthroscopic, and open anterior stabilization procedures. Baseline demographic data and patient outcomes questionnaires were collected with initial physical examination, treatment, surgical findings, and surgical repair details. At the 6-month follow-up visit, ROM and strength measurements were collected and compared with preoperative measurements. There were 348 patients identified who underwent surgical treatment for anterior shoulder instability. Of these, 259 patients (74.0%) returned to baseline, and 89 (26.0%) did not return to baseline shoulder ROM (≥20° loss of ROM) or strength. A higher Beighton score (P = .01) and number of dislocations (P baseline ROM and strength at early follow-up. No surgical variables were found to influence return to baseline function, including open vs. arthroscopic surgery, primary vs. revision surgery, and number of suture anchors. By 4 to 8 months postoperatively, 76% of patients return to baseline ROM, 98% return to baseline strength, and 74% return to both baseline ROM and strength. An increased number of dislocations and generalized joint laxity were associated with failure to return to baseline ROM and strength at early follow-up after anterior shoulder instability surgery. Copyright © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

External respiratory motion for abdominal radiotherapy patients: implications for patient alignment

International Nuclear Information System (INIS)

Kearvell, Rachel; Ebert, Martin A.

2003-01-01

Conformal external beam radiotherapy relies on accurate spatial positioning of the tumor and normal tissues during treatment. For abdominal patients, this is complicated by the motion of internal organs and the external patient contour due to respiration. As external motion influences the degree of accuracy achievable in patient setup, this motion was studied to provide indication of motions occurring during treatment, as well as to assess the technique of breath-holding at exhale (B-HEX). The motion of external abdominal points (anterior and right lateral) of a series of volunteers was tracked in real-time using an infrared tracking system, with the volunteers in treatment position. The resulting motion data was assessed to evaluate (1) the change in position of each point per breath/breath-hold, (2) the change in position between breaths/breath-holds, and (3) the change in position across the whole recording time. Analysis shows that, for the anterior abdominal point, there is little difference in the variation of position with time for free-breathing as opposed to the B-HEX technique. For the lateral point however, the B-HEX technique reduces the motion during each treatment cycle (i.e., during the breath-hold) and over an extended period (i.e., during a series of breath-holds). The B-HEX technique thus provides greater accuracy for setup to lateral markers and provides the opportunity to reduce systematic and random localization errors

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

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

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

Motion correction in thoracic positron emission tomography

CERN Document Server

Gigengack, Fabian; Dawood, Mohammad; Schäfers, Klaus P

2015-01-01

Respiratory and cardiac motion leads to image degradation in Positron Emission Tomography (PET), which impairs quantification. In this book, the authors present approaches to motion estimation and motion correction in thoracic PET. The approaches for motion estimation are based on dual gating and mass-preserving image registration (VAMPIRE) and mass-preserving optical flow (MPOF). With mass-preservation, image intensity modulations caused by highly non-rigid cardiac motion are accounted for. Within the image registration framework different data terms, different variants of regularization and parametric and non-parametric motion models are examined. Within the optical flow framework, different data terms and further non-quadratic penalization are also discussed. The approaches for motion correction particularly focus on pipelines in dual gated PET. A quantitative evaluation of the proposed approaches is performed on software phantom data with accompanied ground-truth motion information. Further, clinical appl...

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.

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

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

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.

The effect of respiratory cycle and radiation beam-on timing on the dose distribution of free-breathing breast treatment using dynamic IMRT

International Nuclear Information System (INIS)

Ding Chuxiong; Li Xiang; Huq, M. Saiful; Saw, Cheng B.; Heron, Dwight E.; Yue, Ning J.

2007-01-01

In breast cancer treatment, intensity-modulated radiation therapy (IMRT) can be utilized to deliver more homogeneous dose to target tissues to minimize the cosmetic impact. We have investigated the effect of the respiratory cycle and radiation beam-on timing on the dose distribution in free-breathing dynamic breast IMRT treatment. Six patients with early stage cancer of the left breast were included in this study. A helical computed tomography (CT) scan was acquired for treatment planning. A four-dimensional computed tomography (4D CT) scan was obtained right after the helical CT scan with little or no setup uncertainty to simulate patient respiratory motion. After optimizing based on the helical CT scan, the sliding-window dynamic multileaf collimator (DMLC) leaf sequence was segmented into multiple sections that corresponded to various respiratory phases per respiratory cycle and radiation beam-on timing. The segmented DMLC leaf sections were grouped according to respiratory phases and superimposed over the radiation fields of corresponding 4D CT image set. Dose calculation was then performed for each phase of the 4D CT scan. The total dose distribution was computed by accumulating the contribution of dose from each phase to every voxel in the region of interest. This was tracked by a deformable registration program throughout all of the respiratory phases of the 4D CT scan. A dose heterogeneity index, defined as the ratio between (D 20 -D 80 ) and the prescription dose, was introduced to numerically illustrate the impact of respiratory motion on the dose distribution of treatment volume. A respiratory cycle range of 4-8 s and randomly distributed beam-on timing were assigned to simulate the patient respiratory motion during the free-breathing treatment. The results showed that the respiratory cycle period and radiation beam-on timing presented limited impact on the target dose coverage and slightly increased the target dose heterogeneity. This motion impact

Whole-heart coronary MRA with 3D affine motion correction using 3D image-based navigation.

Science.gov (United States)

Henningsson, Markus; Prieto, Claudia; Chiribiri, Amedeo; Vaillant, Ghislain; Razavi, Reza; Botnar, René M

2014-01-01

Robust motion correction is necessary to minimize respiratory motion artefacts in coronary MR angiography (CMRA). The state-of-the-art method uses a 1D feet-head translational motion correction approach, and data acquisition is limited to a small window in the respiratory cycle, which prolongs the scan by a factor of 2-3. The purpose of this work was to implement 3D affine motion correction for Cartesian whole-heart CMRA using a 3D navigator (3D-NAV) to allow for data acquisition throughout the whole respiratory cycle. 3D affine transformations for different respiratory states (bins) were estimated by using 3D-NAV image acquisitions which were acquired during the startup profiles of a steady-state free precession sequence. The calculated 3D affine transformations were applied to the corresponding high-resolution Cartesian image acquisition which had been similarly binned, to correct for respiratory motion between bins. Quantitative and qualitative comparisons showed no statistical difference between images acquired with the proposed method and the reference method using a diaphragmatic navigator with a narrow gating window. We demonstrate that 3D-NAV and 3D affine correction can be used to acquire Cartesian whole-heart 3D coronary artery images with 100% scan efficiency with similar image quality as with the state-of-the-art gated and corrected method with approximately 50% scan efficiency. Copyright © 2013 Wiley Periodicals, Inc.

Simulation of spatiotemporal CT data sets using a 4D MRI-based lung motion model.

Science.gov (United States)

Marx, Mirko; Ehrhardt, Jan; Werner, René; Schlemmer, Heinz-Peter; Handels, Heinz

2014-05-01

Four-dimensional CT imaging is widely used to account for motion-related effects during radiotherapy planning of lung cancer patients. However, 4D CT often contains motion artifacts, cannot be used to measure motion variability, and leads to higher dose exposure. In this article, we propose using 4D MRI to acquire motion information for the radiotherapy planning process. From the 4D MRI images, we derive a time-continuous model of the average patient-specific respiratory motion, which is then applied to simulate 4D CT data based on a static 3D CT. The idea of the motion model is to represent the average lung motion over a respiratory cycle by cyclic B-spline curves. The model generation consists of motion field estimation in the 4D MRI data by nonlinear registration, assigning respiratory phases to the motion fields, and applying a B-spline approximation on a voxel-by-voxel basis to describe the average voxel motion over a breathing cycle. To simulate a patient-specific 4D CT based on a static CT of the patient, a multi-modal registration strategy is introduced to transfer the motion model from MRI to the static CT coordinates. Differences between model-based estimated and measured motion vectors are on average 1.39 mm for amplitude-based binning of the 4D MRI data of three patients. In addition, the MRI-to-CT registration strategy is shown to be suitable for the model transformation. The application of our 4D MRI-based motion model for simulating 4D CT images provides advantages over standard 4D CT (less motion artifacts, radiation-free). This makes it interesting for radiotherapy planning.

Development of respiratory motion reduction device system (RMRDs) for radiotherapy in moving tumors

International Nuclear Information System (INIS)

Lee, Suk; Yang, Dae-Sik; Choil, Myung-Sun; Kim, Chui-Yong

2004-01-01

The internal target volume (ITV) for tumors in the abdomen or thorax includes sufficient margin for breathing-related movement of tumor volumes during treatment. Depending on the location of the tumor, the magnitude of the ITV margin extends from 1 to 3 cm, which increases substantially the volume of the irradiated normal tissue, hence resulting in an increase in normal tissue complication probability (NTCP). We developed a simple and handy method which can reduce ITV margins in patients with moving tumors: the respiratory motion reduction device system (RMRDs). The patient's clinical database was structured for moving tumor patients and patient set-up error measurement and immobilization device effects were investigated. The system is composed of the respiration presser device (RPD) utilized in the prone position and the abdominal strip device (ASD) utilized in the supine position, and the analysis program, which enables analysis of patient set-up reproducibility. It was tested for analyzing the diaphragm movement from patients with RMRDs, the magnitude of the ITV margin was determined and the dose-volume histogram (DVH) was computed using treatment planning software. The dose to normal tissue in patients with and without RMRDs was analyzed by comparing the fraction of the normal liver receiving 50% of the isocenter dose. Average diaphragm movement due to respiration was 16±1.9 mm in the case of the supine position, and 12±1.9 mm in the case of the prone position. When utilizing the RMRDs, which was personally developed in our hospital, the value was reduced to 5±1.4 mm, and in the case in which the belt immobilization device was utilized, the value was reduced to 3±0.9 mm. In the case where the strip device was utilized, the value was proven to reduce to 4±0.3 mm. As a result of analyzing the volume of normal liver where 50% of the prescription dose is irradiated in DVH according to the radiation treatment planning, the use of the RMRD can create a reduction

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.

Oral Probiotics Alter Healthy Feline Respiratory Microbiota.

Science.gov (United States)

Vientós-Plotts, Aida I; Ericsson, Aaron C; Rindt, Hansjorg; Reinero, Carol R

2017-01-01

Probiotics have been advocated as a novel therapeutic approach to respiratory disease, but knowledge of how oral administration of probiotics influences the respiratory microbiota is needed. Using 16S rRNA amplicon sequencing of bacterial DNA our objective was to determine whether oral probiotics changed the composition of the upper and lower airway, rectal, and blood microbiota. We hypothesized that oral probiotics would modulate the respiratory microbiota in healthy cats, demonstrated by the detection and/or increased relative abundance of the probiotic bacterial species and altered composition of the microbial population in the respiratory tract. Six healthy young research cats had oropharyngeal (OP), bronchoalveolar lavage fluid (BALF), rectal, and blood samples collected at baseline and 4 weeks after receiving oral probiotics. 16S rRNA gene amplicon libraries were sequenced, and coverage, richness, and relative abundance of representative operational taxonomic units (OTUs) were determined. Hierarchical and principal component analyses (PCA) demonstrated relatedness of samples. Mean microbial richness significantly increased only in the upper and lower airways. The number of probiotic OTUs (out of 5 total) that significantly increased in relative abundance vs. baseline was 5 in OP, 3 in BAL and 2 in feces. Using hierarchical clustering, BALF and blood samples grouped together after probiotic administration, and PERMANOVA supported that these two sites underwent significant changes in microbial composition. PERMANOVA revealed that OP and rectal samples had microbial population compositions that did not significantly change. These findings were visualized via PCA, which revealed distinct microbiomes in each site; samples clustered more tightly at baseline and had more variation after probiotic administration. This is the first study describing the effect of oral probiotics on the respiratory microbiota via detection of probiotic species in the airways. Finding

Oral Probiotics Alter Healthy Feline Respiratory Microbiota

Directory of Open Access Journals (Sweden)

Aida I. Vientós-Plotts

2017-07-01

Full Text Available Probiotics have been advocated as a novel therapeutic approach to respiratory disease, but knowledge of how oral administration of probiotics influences the respiratory microbiota is needed. Using 16S rRNA amplicon sequencing of bacterial DNA our objective was to determine whether oral probiotics changed the composition of the upper and lower airway, rectal, and blood microbiota. We hypothesized that oral probiotics would modulate the respiratory microbiota in healthy cats, demonstrated by the detection and/or increased relative abundance of the probiotic bacterial species and altered composition of the microbial population in the respiratory tract. Six healthy young research cats had oropharyngeal (OP, bronchoalveolar lavage fluid (BALF, rectal, and blood samples collected at baseline and 4 weeks after receiving oral probiotics. 16S rRNA gene amplicon libraries were sequenced, and coverage, richness, and relative abundance of representative operational taxonomic units (OTUs were determined. Hierarchical and principal component analyses (PCA demonstrated relatedness of samples. Mean microbial richness significantly increased only in the upper and lower airways. The number of probiotic OTUs (out of 5 total that significantly increased in relative abundance vs. baseline was 5 in OP, 3 in BAL and 2 in feces. Using hierarchical clustering, BALF and blood samples grouped together after probiotic administration, and PERMANOVA supported that these two sites underwent significant changes in microbial composition. PERMANOVA revealed that OP and rectal samples had microbial population compositions that did not significantly change. These findings were visualized via PCA, which revealed distinct microbiomes in each site; samples clustered more tightly at baseline and had more variation after probiotic administration. This is the first study describing the effect of oral probiotics on the respiratory microbiota via detection of probiotic species in the

An externally and internally deformable, programmable lung motion phantom

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Cheung, Yam; Sawant, Amit, E-mail: amit.sawant@utsouthwestern.edu [UT Southwestern Medical Center, University of Texas, Dallas, Texas 75390 (United States)

2015-05-15

Purpose: Most clinically deployed strategies for respiratory motion management in lung radiotherapy (e.g., gating and tracking) use external markers that serve as surrogates for tumor motion. However, typical lung phantoms used to validate these strategies are based on a rigid exterior and a rigid or a deformable-interior. Such designs do not adequately represent respiration because the thoracic anatomy deforms internally as well as externally. In order to create a closer approximation of respiratory motion, the authors describe the construction and experimental testing of an externally as well as internally deformable, programmable lung phantom. Methods: The outer shell of a commercially available lung phantom (RS-1500, RSD, Inc.) was used. The shell consists of a chest cavity with a flexible anterior surface, and embedded vertebrae, rib-cage and sternum. A custom-made insert was designed using a piece of natural latex foam block. A motion platform was programmed with sinusoidal and ten patient-recorded lung tumor trajectories. The platform was used to drive a rigid foam “diaphragm” that compressed/decompressed the phantom interior. Experimental characterization comprised of determining the reproducibility and the external–internal correlation of external and internal marker trajectories extracted from kV x-ray fluoroscopy. Experiments were conducted to illustrate three example applications of the phantom—(i) validating the geometric accuracy of the VisionRT surface photogrammetry system; (ii) validating an image registration tool, NiftyReg; and (iii) quantifying the geometric error due to irregular motion in four-dimensional computed tomography (4DCT). Results: The phantom correctly reproduced sinusoidal and patient-derived motion, as well as realistic respiratory motion-related effects such as hysteresis. The reproducibility of marker trajectories over multiple runs for sinusoidal as well as patient traces, as characterized by fluoroscopy, was within 0

Body temperature and motion: Evaluation of an online monitoring system in pigs challenged with Porcine Reproductive & Respiratory Syndrome Virus.

Science.gov (United States)

Süli, Tamás; Halas, Máté; Benyeda, Zsófia; Boda, Réka; Belák, Sándor; Martínez-Avilés, Marta; Fernández-Carrión, Eduardo; Sánchez-Vizcaíno, José Manuel

2017-10-01

Highly contagious and emerging diseases cause significant losses in the pig producing industry worldwide. Rapid and exact acquisition of real-time data, like body temperature and animal movement from the production facilities would enable early disease detection and facilitate adequate response. In this study, carried out within the European Union research project RAPIDIA FIELD, we tested an online monitoring system on pigs experimentally infected with the East European subtype 3 Porcine Reproductive & Respiratory Syndrome Virus (PRRSV) strain Lena. We linked data from different body temperature measurement methods and the real-time movement of the pigs. The results showed a negative correlation between body temperature and movement of the animals. The correlation was similar with both body temperature obtaining methods, rectal and thermal sensing microchip, suggesting some advantages of body temperature measurement with transponders compared with invasive and laborious rectal measuring. We also found a significant difference between motion values before and after the challenge with a virulent PRRSV strain. The decrease in motion values was noticeable before any clinical sign was recorded. Based on our results the online monitoring system could represent a practical tool in registering early warning signs of health status alterations, both in experimental and commercial production settings. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of training and rest on respiratory mechanical properties in racing sled dogs.

Science.gov (United States)

Davis, Michael; Williamson, Katherine; McKenzie, Erica; Royer, Christopher; Payton, Mark; Nelson, Stuart

2005-02-01

Racing Alaskan sled dogs develop exercise-induced airway inflammation, similar to that reported for elite human athletes participating in cold-weather sports. These human athletes also have airway hyperresponsiveness, but airway function in sled dogs has not been measured. To compare respiratory mechanical properties in trained, rested Alaskan sled dogs with typical laboratory hounds, and to determine whether subsequent training alters respiratory mechanical properties. Nineteen healthy adult Alaskan sled dogs were compared with five healthy adult mixed-breed laboratory hounds. All dogs were rested for at least 4 months before examination. Respiratory mechanical properties were measured while the dogs were anesthetized and ventilated with a piston ventilator. The mean respiratory resistance and compliance measurements for 20 consecutive breaths were used as baseline values immediately before measurement of respiratory reactivity. Respiratory reactivity was the mean of 20 consecutive breaths immediately after the administration of aerosol histamine, expressed as the percentage change in prehistamine measurements. After the initial examinations, the sled dogs were divided into exercised and controls. Exercised dogs were trained for competitive endurance racing. Both groups were examined after 2 and 4 months of training. Alaskan sled dogs had greater respiratory compliance reactivity to histamine (77.47 +/- 8.58% baseline) compared with laboratory dogs (87.60 +/- 9.22% baseline). There was no effect of training on respiratory mechanical properties detected in racing sled dogs. Racing Alaskan sled dogs have airway dysfunction similar to "ski asthma" that persists despite having 4 months of rest. These findings suggest that repeated exercise in cold conditions can lead to airway disease that does not readily resolve with cessation of exercise.

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

Influence of physiologic motion on the appearance of tissue in MR images

International Nuclear Information System (INIS)

Ehman, R.L.; McNamara, M.T.; Brasch, R.C.; Felmlee, J.P.; Gray, J.E.; Higgins, C.B.

1986-01-01

Studies were performed to determine the possible influence of physiologic motion on the parenchymal intensity of organs in magnetic resonance (MR) images. It is known that periodic motion associated with respiration and cardiac function causes characteristic artifacts in spin-warp images. The present study shows that bulk motion can also cause striking intensity changes at velocities equivalent to the craniocaudal respiratory excursion of organs in the upper abdomen. The magnitude of the effect depends on the velocity and direction of motion with respect to the three orthogonal axes of the imager and on the technical details of the imager and pulse sequence. Large systematic errors in calculated tissue relaxation times are possible due to this phenomenon. The findings have important implications for clinical imaging because motion can cause artifactual changes in the gray-scale relationships among tissues. Some pulse sequences are much less sensitive to these effects. These results provide guidance for selecting MR techniques that reduce the detrimental effect of respiratory and other physiologic motion on examinations of the upper abdomen and thorax

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

Development and validation of real-time simulation of X-ray imaging with respiratory motion.

Science.gov (United States)

Vidal, Franck P; Villard, Pierre-Frédéric

2016-04-01

We present a framework that combines evolutionary optimisation, soft tissue modelling and ray tracing on GPU to simultaneously compute the respiratory motion and X-ray imaging in real-time. Our aim is to provide validated building blocks with high fidelity to closely match both the human physiology and the physics of X-rays. A CPU-based set of algorithms is presented to model organ behaviours during respiration. Soft tissue deformation is computed with an extension of the Chain Mail method. Rigid elements move according to kinematic laws. A GPU-based surface rendering method is proposed to compute the X-ray image using the Beer-Lambert law. It is provided as an open-source library. A quantitative validation study is provided to objectively assess the accuracy of both components: (i) the respiration against anatomical data, and (ii) the X-ray against the Beer-Lambert law and the results of Monte Carlo simulations. Our implementation can be used in various applications, such as interactive medical virtual environment to train percutaneous transhepatic cholangiography in interventional radiology, 2D/3D registration, computation of digitally reconstructed radiograph, simulation of 4D sinograms to test tomography reconstruction tools. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of tumor motion effect in canine model for diagnostic and radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Woo, Sangkeun; Nam, Taewon; Kim, Kyeongmin [Molecular Imaging Research Center, Seoul (Korea, Republic of); Park, Seungwoo; Han, Suchul; Ji, Younghoon [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Park, Nohwon; Eom, Kidong [Konkuk Univ., Seoul (Korea, Republic of)

2013-05-15

The internal organs move up to 35mm maximum and it provides information and uncertainty that has been distorted in the diagnosis and treatment. Previous most studies for the effect of respiration have been performed with external monitoring systems but it cannot represent internal organ motion such as liver, pancreas, and lung. Positron emission tomography (PET) is more influenced by motion than computed tomography (CT) and magnetic resonance imaging (MRI) since measurement time for image acquisition is longer than CT and MRI. Thus, count of tumor is to be underestimated and region of tumor is to be overestimated. The first aim of this study was developing the artificial pulmonary nodule which can be performed non-invasive transplant into thorax of dogs and second is to assess the effect of respiratory motion on PET image with evaluating the applicability of the artificial model using dogs for diagnosis and treatment. The developed artificial pulmonary nodule showed reproducibility and motion effect as respiratory cycle and it was verified in PET images. Radiation dose estimated was not changed and was reduced slightly of 10 rpm and 15 rpm, respectively, in both of glass dosimeter and ion chamber. The developed artificial pulmonary nodule will be useful tool for evaluating respiratory motion and better research performance for diagnosis and treatment will be expected with performing simulated experiment using the nodule conducted in this study.

Volume-monitored chest CT: a simplified method for obtaining motion-free images near full inspiratory and end expiratory lung volumes

Energy Technology Data Exchange (ETDEWEB)

Mueller, Kathryn S. [The Ohio State University College of Medicine, Columbus, OH (United States); Long, Frederick R. [Nationwide Children' s Hospital, The Children' s Radiological Institute, Columbus, OH (United States); Flucke, Robert L. [Nationwide Children' s Hospital, Department of Pulmonary Medicine, Columbus, OH (United States); Castile, Robert G. [The Research Institute at Nationwide Children' s Hospital, Center for Perinatal Research, Columbus, OH (United States)

2010-10-15

Lung inflation and respiratory motion during chest CT affect diagnostic accuracy and reproducibility. To describe a simple volume-monitored (VM) method for performing reproducible, motion-free full inspiratory and end expiratory chest CT examinations in children. Fifty-two children with cystic fibrosis (mean age 8.8 {+-} 2.2 years) underwent pulmonary function tests and inspiratory and expiratory VM-CT scans (1.25-mm slices, 80-120 kVp, 16-40 mAs) according to an IRB-approved protocol. The VM-CT technique utilizes instruction from a respiratory therapist, a portable spirometer and real-time documentation of lung volume on a computer. CT image quality was evaluated for achievement of targeted lung-volume levels and for respiratory motion. Children achieved 95% of vital capacity during full inspiratory imaging. For end expiratory scans, 92% were at or below the child's end expiratory level. Two expiratory exams were judged to be at suboptimal volumes. Two inspiratory (4%) and three expiratory (6%) exams showed respiratory motion. Overall, 94% of scans were performed at optimal volumes without respiratory motion. The VM-CT technique is a simple, feasible method in children as young as 4 years to achieve reproducible high-quality full inspiratory and end expiratory lung CT images. (orig.)

A programmable motion phantom for quality assurance of motion management in radiotherapy

International Nuclear Information System (INIS)

Dunn, L.; Franich, R.D.; Kron, T.; Taylor, M.L.; Johnston, P.N.; McDermott, L.N.; Callahan, J.

2012-01-01

A commercially available motion phantom (QUASAR, Modus Medical) was modified for programmable motion control with the aim of reproducing patient respiratory motion in one dimension in both the anterior–posterior and superior–inferior directions, as well as, providing controllable breath-hold and sinusoidal patterns for the testing of radiotherapy gating systems. In order to simulate realistic patient motion, the DC motor was replaced by a stepper motor. A separate 'chest-wall' motion platform was also designed to accommodate a variety of surrogate marker systems. The platform employs a second stepper motor that allows for the decoupling of the chest-wall and insert motion. The platform's accuracy was tested by replicating patient traces recorded with the Varian real-time position management (RPM) system and comparing the motion platform's recorded motion trace with the original patient data. Six lung cancer patient traces recorded with the RPM system were uploaded to the motion platform's in-house control software and subsequently replicated through the phantom motion platform. The phantom's motion profile was recorded with the RPM system and compared to the original patient data. Sinusoidal and breath-hold patterns were simulated with the motion platform and recorded with the RPM system to verify the systems potential for routine quality assurance of commercial radiotherapy gating systems. There was good correlation between replicated and actual patient data (P 0.003). Mean differences between the location of maxima in replicated and patient data-sets for six patients amounted to 0.034 cm with the corresponding minima mean equal to 0.010 cm. The upgraded motion phantom was found to replicate patient motion accurately as well as provide useful test patterns to aid in the quality assurance of motion management methods and technologies.