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Sample records for assessing four-dimensional radiotherapy

  1. Predicting respiratory motion for four-dimensional radiotherapy

    International Nuclear Information System (INIS)

    sinusoidal model. With the adaptive filter, average prediction errors of less than 0.2 cm (1σ) are possible for response times less than 0.4 seconds. In comparing prediction error with system latency error (no prediction), the adaptive filter model exhibited lesser prediction errors as compared to the sinusoidal model, especially for longer response time values (>0.4 seconds). At smaller response time values (<0.4 seconds), improvements in prediction error reduction are required for both predictive models in order to maximize gains in position accuracy due to prediction. Respiratory motion patterns are inherently complex in nature. While linear prediction-based prediction models perform satisfactorily for shorter response times, their prediction accuracy significantly deteriorates for longer response times. Successful implementation of real-time target-tracking-based radiotherapy requires response times less than 0.4 seconds or improved prediction algorithms

  2. Image-guided radiotherapy (IGRT) and four dimensional radiotherapy (4DRT)

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    a metallic marker in the tumour can be determined with an accuracy of 1 mm every 0.033 second during radiotherapy. This dramatic improvement in the localization of moving tumours has made it possible to irradiate the tumour at a favourable phase of respiration. We have improved the 3D radiotherapy planning system (3D RTP) to incorporate the time factor into the treatment planning and called it four dimensional (4D) treatment planning. More than two hundred patients with lung, liver, and prostate cancers were treated using the RTRT system. Internal tumour motion was investigated using the fiducial markers. It revealed that inter-fractional and intra-fractional changes of amplitude and speed of the tumour motion were larger than we expected. Correction of target localization by using the RTRT system at the start of radiotherapy everyday is useful to reduce inter-fractional setup error for brain, spinal cord, head and neck, esophagus, prostate, and uterus tumours. For reducing intra-fractional error due to organ motion, the RTRT system was also shown to be useful for lung, liver, pancreas, and adrenal tumours with a little exposure of diagnostic X ray. Clinical benefits of these techniques have been suggested for many organs to reduce normal tissue complications. Migration of the marker, shrinkage and deformation of the tumour during radiotherapy are the subjects to be carefully controlled during the radiotherapy

  3. A novel four-dimensional radiotherapy method for lung cancer: imaging, treatment planning and delivery

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    Alasti, H.; Cho, Y. B.; Vandermeer, A. D.; Abbas, A.; Norrlinger, B.; Shubbar, S.; Bezjak, A.

    2006-06-01

    We present treatment planning methods based on four-dimensional computed tomography (4D-CT) to incorporate tumour motion using (1) a static field and (2) a dynamic field. Static 4D fields are determined to include the target in all breathing phases, whereas dynamic 4D fields are determined to follow the shape of the tumour assessed from 4D-CT images with a dynamic weighting factor. The weighting factor selection depends on the reliability of patient breathing and limitations of the delivery system. The static 4D method is compared with our standard protocol for gross tumour volume (GTV) coverage, mean lung dose and V20. It was found that the GTV delineated on helical CT without incorporating breathing motion does not adequately represent the target compared to the GTV delineated from 4D-CT. Dosimetric analysis indicates that the static 4D-CT based technique results in a reduction of the mean lung dose compared with the standard protocol. Measurements on a moving phantom and simulations indicated that 4D radiotherapy (4D-RT) synchronized with respiration-induced motion further reduces mean lung dose and V20, and may allow safe application of dose escalation and CRT/IMRT. The motions of the chest cavity, tumour and thoracic structures of 24 lung cancer patients are also analysed.

  4. Four-dimensional dose evaluation using deformable image registration in radiotherapy for liver cancer

    International Nuclear Information System (INIS)

    Purpose: In order to evaluate the dosimetric impact of respiratory motion on the dose delivered to the target volume and critical organs during free-breathing radiotherapy, a four-dimensional dose was evaluated using deformable image registration (DIR). Methods: Four-dimensional computed tomography (4DCT) images were acquired for 11 patients who were treated for liver cancer. Internal target volume-based treatment planning and dose calculation (3D dose) were performed using the end-exhalation phase images. The four-dimensional dose (4D dose) was calculated based on DIR of all phase images from 4DCT to the planned image. Dosimetric parameters from the 4D dose, were calculated and compared with those from the 3D dose. Results: There was no significant change of the dosimetric parameters for gross tumor volume (p > 0.05). The increase Dmean and generalized equivalent uniform dose (gEUD) for liver were by 3.1%± 3.3% (p= 0.003) and 2.8%± 3.3% (p= 0.008), respectively, and for duodenum, they were decreased by 15.7%± 11.2% (p= 0.003) and 15.1%± 11.0% (p= 0.003), respectively. The Dmax and gEUD for stomach was decreased by 5.3%± 5.8% (p= 0.003) and 9.7%± 8.7% (p= 0.003), respectively. The Dmax and gEUD for right kidney was decreased by 11.2%± 16.2% (p= 0.003) and 14.9%± 16.8% (p= 0.005), respectively. For left kidney, Dmax and gEUD were decreased by 11.4%± 11.0% (p= 0.003) and 12.8%± 12.1% (p= 0.005), respectively. The NTCP values for duodenum and stomach were decreased by 8.4%± 5.8% (p= 0.003) and 17.2%± 13.7% (p= 0.003), respectively. Conclusions: The four-dimensional dose with a more realistic dose calculation accounting for respiratory motion revealed no significant difference in target coverage and potentially significant change in the physical and biological dosimetric parameters in normal organs during free-breathing treatment.

  5. Comparison between audio-only and audiovisual biofeedback for regulating patients' respiration during four-dimensional radiotherapy

    OpenAIRE

    Yu, Jesang; Choi, Ji Hoon; Ma, Sun Young; Jeung, Tae Sig; Lim, Sangwook

    2015-01-01

    Purpose To compare audio-only biofeedback to conventional audiovisual biofeedback for regulating patients' respiration during four-dimensional radiotherapy, limiting damage to healthy surrounding tissues caused by organ movement. Materials and Methods Six healthy volunteers were assisted by audiovisual or audio-only biofeedback systems to regulate their respirations. Volunteers breathed through a mask developed for this study by following computer-generated guiding curves displayed on a scree...

  6. An analysis of respiratory induced kidney motion on four-dimensional computed tomography and its implications for stereotactic kidney radiotherapy

    International Nuclear Information System (INIS)

    Stereotactic ablative body radiotherapy (SABR) is an emerging treatment modality for primary renal cell carcinoma. To account for respiratory-induced target motion, an internal target volume (ITV) concept is often used in treatment planning of SABR. The purpose of this study is to assess patterns of kidney motion and investigate potential surrogates of kidney displacement with the view of ITV verification during treatment. Datasets from 71 consecutive patients with free breathing four-dimensional computed tomography (4DCT) planning scans were included in this study. The displacement of the left and right hemi-diaphragm, liver dome and abdominal wall were measured and tested for correlation with the displacement of the both kidneys and patient breathing frequency. Nine patients were excluded due to severe banding artifact. Of 62 evaluable patients, the median age was 68 years, with 41 male patients and 21 female patients. The mean (range) of the maximum, minimum and average breathing frequency throughout the 4DCTs were 20.1 (11–38), 15.1 (9–24) and 17.3 (9–27.5) breaths per minute, respectively. The mean (interquartile range) displacement of the left and right kidneys was 0.74 cm (0.45-0.98 cm) and 0.75 cm (0.49-0.97) respectively. The amplitude of liver-dome motion was correlated with right kidney displacement (r=0.52, p<0.001), but not with left kidney displacement (p=0.796). There was a statistically significant correlation between the magnitude of right kidney displacement and that of abdominal displacement (r=0.36, p=0.004), but not the left kidney (r=0.24, p=0.056). Hemi-diaphragm displacements were correlated with kidney displacements respectively, with a weaker correlation for the left kidney/left diaphragm (r=0.45, [95% CI 0.22 to 0.63], p=<0.001) than for the right kidney/right diaphragm (r=0.57, [95% CI 0.37 to 0.72], p=<0.001). For the majority of patients, maximal left and right kidney displacement is subcentimeter in magnitude. The magnitude of

  7. Impact of Four-Dimensional Computed Tomography Pulmonary Ventilation Imaging-Based Functional Avoidance for Lung Cancer Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To quantify the dosimetric impact of four-dimensional computed tomography (4D-CT) pulmonary ventilation imaging-based functional treatment planning that avoids high-functional lung regions. Methods and Materials: 4D-CT ventilation images were created from 15 non-small-cell lung cancer patients using deformable image registration and quantitative analysis of the resultant displacement vector field. For each patient, anatomic and functional plans were created for intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Consistent beam angles and dose-volume constraints were used for all cases. The plans with Radiation Therapy Oncology Group (RTOG) 0617-defined major deviations were modified until clinically acceptable. Functional planning spared the high-functional lung, and anatomic planning treated the lungs as uniformly functional. We quantified the impact of functional planning compared with anatomic planning using the two- or one-tailed t test. Results: Functional planning led to significant reductions in the high-functional lung dose, without significantly increasing other critical organ doses, but at the expense of significantly degraded the planning target volume (PTV) conformity and homogeneity. The average reduction in the high-functional lung mean dose was 1.8 Gy for IMRT (p < .001) and 2.0 Gy for VMAT (p < .001). Significantly larger changes occurred in the metrics for patients with a larger amount of high-functional lung adjacent to the PTV. Conclusion: The results of the present study have demonstrated the impact of 4D-CT ventilation imaging-based functional planning for IMRT and VMAT for the first time. Our findings indicate the potential of functional planning in lung functional avoidance for both IMRT and VMAT, particularly for patients who have high-functional lung adjacent to the PTV.

  8. Development of a four-dimensional image-guided radiotherapy system with a gimbaled X-ray head

    International Nuclear Information System (INIS)

    Purpose: To develop and evaluate a new four-dimensional image-guided radiotherapy system, which enables precise setup, real-time tumor tracking, and pursuit irradiation. Methods and Materials: The system has an innovative gimbaled X-ray head that enables small-angle (±2.4o) rotations (pan and tilt) along the two orthogonal gimbals. This design provides for both accurate beam positioning at the isocenter by actively compensating for mechanical distortion and quick pursuit of the target. The X-ray head is composed of an ultralight C-band linear accelerator and a multileaf collimator. The gimbaled X-ray head is mounted on a rigid O-ring structure with an on-board imaging subsystem composed of two sets of kilovoltage X-ray tubes and flat panel detectors, which provides a pair of radiographs, cone beam computed tomography images useful for image guided setup, and real-time fluoroscopic monitoring for pursuit irradiation. Results: The root mean square accuracy of the static beam positioning was 0.1 mm for 360o of O-ring rotation. The dynamic beam response and positioning accuracy was ±0.6 mm for a 0.75 Hz, 40-mm stroke and ±0.4 mm for a 2.0 Hz, 8-mm stroke. The quality of the images was encouraging for using the tomography-based setup. Fluoroscopic images were sufficient for monitoring and tracking lung tumors. Conclusions: Key functions and capabilities of our new system are very promising for precise image-guided setup and for tracking and pursuit irradiation of a moving target

  9. A study on the influence of breathing phases in intensity-modulated radiotherapy of lung tumours using four-dimensional CT

    OpenAIRE

    Wu, W. C.; Chan, C. L.; Wong, Y W; Cuijpers, J P

    2010-01-01

    During gated intensity-modulated radiotherapy (IMRT) treatment for patients with inoperable non-small cell lung cancer (NSCLC), the end-expiration (EE) phase of respiratory is more stable, whereas end-inspiration (EI) spares more normal lung tissue. This study compared the relative plan quality based on dosimetric and biological indices of the planning target volume (PTV) and organs at risk (OARs) between EI and EE in gated IMRT. 16 Stage I NSCLC patients, who were scanned by four-dimensional...

  10. Detection of interfraction displacement and volume variance during radiotherapy of primary thoracic esophageal cancer based on repeated four-dimensional CT scans

    International Nuclear Information System (INIS)

    To investigate the interfraction displacement and volume variation of primary thoracic esophagus carcinoma with enhanced four-dimensional computed tomography (4DCT) scanning during fractionated radiotherapy. 4DCT data sets were acquired at the time of treatment simulation and every ten fraction for each of 32 patients throughout treatment. Scans were registered to baseline (simulation) 4DCT scans by using bony landmarks. The gross tumor volumes (GTVs) were delineated on each data set. Coordinates of the GTV centroids were acquired on each respiration phase. Distance between center of the GTV contour on the simulation scan and the centers on subsequent scans were used to assess interfraction displacement between fractions. Volumes were constructed using three approaches: The GTV delineated from the maximum intensity projection (MIP) was defined IGTVMIP, all 10 GTVs were combined to form IGTV10, GTVmean was the average of all 10 phases of each GTV. Interfraction displacement in left-right (LR), anterior-posterior (AP), superior-inferior (SI) directions and 3D vector were 0.13 ± 0.09 cm, 0.16 ± 0.12 cm, 0.34 ± 0.26 cm and 0.43 ± 0.24 cm, respectively between the tenth fraction and simulation 4DCT scan. 0.14 ± 0.09 cm, 0.19 ± 0.16 cm, 0.45 ± 0.43 cm and 0.56 ± 0.40 cm in LR, AP, SI and 3D vector respectively between the twentieth fraction and simulation 4DCT scan. Displacement in SI direction was larger than LR and AP directions during treatment. For distal esophageal cancer, increased interfraction displacements were observed in SI direction and 3D vector (P = 0.002 and P = 0.001, respectively) during radiotherapy. The volume of GTVmean, IGTVMIP, and IGTV10 decreased significantly at the twentieth fraction for middle (median: 34.01%, 33.09% and 28.71%, respectively) and distal (median: 22.76%, 25.27% and 23.96%, respectively) esophageal cancer, but for the upper third, no significant variation were observed during radiotherapy. Interfractional displacements in

  11. Novel Assessment of Renal Motion in Children as Measured via Four-Dimensional Computed Tomography

    International Nuclear Information System (INIS)

    Objectives: Abdominal intensity-modulated radiation therapy and proton therapy require quantification of target and organ motion to optimize localization and treatment. Although addressed in adults, there is no available literature on this issue in pediatric patients. We assessed physiologic renal motion in pediatric patients. Methods and Materials: Twenty free-breathing pediatric patients at a median age of 8 years (range, 2–18 years) with intra-abdominal tumors underwent computed tomography simulation and four-dimensional computed tomography acquisition (slice thickness, 3 mm). Kidneys and diaphragms were contoured during eight phases of respiration to estimate center-of-mass motion. We quantified center of kidney mass mobility vectors in three dimensions: anteroposterior (AP), mediolateral (ML), and superoinferior (SI). Results: Kidney motion decreases linearly with decreasing age and height. The 95% confidence interval for the averaged minima and maxima of renal motion in children younger than 9 years was 5–9 mm in the ML direction, 4–11 mm in the AP direction, and 12–25 mm in the SI dimension for both kidneys. In children older than 9 years, the same confidence interval reveals a widening range of motion that was 5–16 mm in the ML direction, 6–17 mm in the AP direction, and 21–52 mm in the SI direction. Although not statistically significant, renal motion correlated with diaphragm motion in older patients. The correlation between diaphragm motion and body mass index was borderline (r = 0.52, p = 0.0816) in younger patients. Conclusions: Renal motion is age and height dependent. Measuring diaphragmatic motion alone does not reliably quantify pediatric renal motion. Renal motion in young children ranges from 5 to 25 mm in orientation-specific directions. The vectors of motion range from 5 to 52 mm in older children. These preliminary data represent novel analyses of pediatric intra-abdominal organ motion.

  12. Four-dimensional dosimetry validation and study in lung radiotherapy using deformable image registration and Monte Carlo techniques

    International Nuclear Information System (INIS)

    Thoracic cancer treatment presents dosimetric difficulties due to respiratory motion and lung inhomogeneity. Monte Carlo and deformable image registration techniques have been proposed to be used in four-dimensional (4D) dose calculations to overcome the difficulties. This study validates the 4D Monte Carlo dosimetry with measurement, compares 4D dosimetry of different tumor sizes and tumor motion ranges, and demonstrates differences of dose-volume histograms (DVH) with the number of respiratory phases that are included in 4D dosimetry. BEAMnrc was used in dose calculations while an optical flow algorithm was used in deformable image registration and dose mapping. Calculated and measured doses of a moving phantom agreed within 3% at the center of the moving gross tumor volumes (GTV). 4D CT image sets of lung cancer cases were used in the analysis of 4D dosimetry. For a small tumor (12.5 cm3) with motion range of 1.5 cm, reduced tumor volume coverage was observed in the 4D dose with a beam margin of 1 cm. For large tumors and tumors with small motion range (around 1 cm), the 4D dosimetry did not differ appreciably from the static plans. The dose-volume histogram (DVH) analysis shows that the inclusion of only extreme respiratory phases in 4D dosimetry is a reasonable approximation of all-phase inclusion for lung cancer cases similar to the ones studied, which reduces the calculation in 4D dosimetry

  13. Reconstitution of internal target volumes by combining four-dimensional computed tomography and a modified slow computed tomography scan in stereotactic body radiotherapy planning for lung cancer

    International Nuclear Information System (INIS)

    To evaluate the volumetric and geometric differences in the ITVs generated by four-dimensional (4D) computed tomography (CT), a modified slow CT scan, and a combination of these CT methods in lung cancer patients treated with stereotactic body radiotherapy (SBRT). Both 4D CT and modified slow CT using a multi-slice CT scanner were performed for SBRT planning in 14 patients with 15 pulmonary targets. Volumetric and geometric analyses were performed for (1) ITVall, generated by combining the gross tumor volumes (GTVs) from all 8 phases of the 4D CT; (2) ITV2, generated by combining the GTVs from 2 extreme phases of the 4D CT; (3) ITVslow, derived from the GTV on the modified slow CT scan; (4) ITVall+slow, generated by combining ITVall and ITVslow; and (5) ITV2+slow, generated by combining ITV2 and ITVslow. Three SBRT plans were performed using 3 ITVs to assess the dosimetric effects on normal lung caused by the various target volumes. ITVall (11.8 ± 8.3 cm3) was significantly smaller than ITVall+slow (12.5 ± 8.9 cm3), with mean values of 5.8% for the percentage volume difference, and a mean of 7.5% of ITVslow was not encompassed in ITVall. The geometric coverages of ITV2 and ITVslow for ITVall were 84.7 ± 6.6% and 76.2 ± 9.3%, respectively, but the coverage for ITVall increased to 90.9 ± 5.9% by using the composite of these two ITVs. There were statistically significant increases in the lung-dose parameters of the plans based on ITVall+slow compared to the plans based on ITVall or ITV2+slow. However, the magnitudes of these differences were relatively small, with a value of less than 3% in all dosimetric parameters. Due to its ability to provides additional motion information, the combination of 4D CT and a modified slow CT scan in SBRT planning for lung cancer can be used to reduce possible errors in true target delineation caused by breathing pattern variations

  14. 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

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

    International Nuclear Information System (INIS)

    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

  16. The effect of irregular breathing patterns on internal target volumes in four-dimensional CT and cone-beam CT images in the context of stereotactic lung radiotherapy

    International Nuclear Information System (INIS)

    Purpose: Stereotactic lung radiotherapy is complicated by tumor motion from patient respiration. Four-dimensional CT (4DCT) imaging is a motion compensation method used in treatment planning to generate a maximum intensity projection (MIP) internal target volume (ITV). Image guided radiotherapy during treatment may involve acquiring a volumetric cone-beam CT (CBCT) image and visually aligning the tumor to the planning 4DCT MIP ITV contour. Moving targets imaged with CBCT can appear blurred and currently there are no studies reporting on the effect that irregular breathing patterns have on CBCT volumes and their alignment to 4DCT MIP ITV contours. The objective of this work was therefore to image a phantom moving with irregular breathing patterns to determine whether any configurations resulted in errors in volume contouring or alignment. Methods: A Perspex thorax phantom was used to simulate a patient. Three wooden “lung” inserts with embedded Perspex “lesions” were moved up to 4 cm with computer-generated motion patterns, and up to 1 cm with patient-specific breathing patterns. The phantom was imaged on 4DCT and CBCT with the same acquisition settings used for stereotactic lung patients in the clinic and the volumes on all phantom images were contoured. This project assessed the volumes for qualitative and quantitative changes including volume, length of the volume, and errors in alignment between CBCT volumes and 4DCT MIP ITV contours. Results: When motion was introduced 4DCT and CBCT volumes were reduced by up to 20% and 30% and shortened by up to 7 and 11 mm, respectively, indicating that volume was being under-represented at the extremes of motion. Banding artifacts were present in 4DCT MIP images, while CBCT volumes were largely reduced in contrast. When variable amplitudes from patient traces were used and CBCT ITVs were compared to 4DCT MIP ITVs there was a distinct trend in reduced ITV with increasing amplitude that was not seen when compared to

  17. Evaluation of Four-Dimensional Computed Tomography-Based Intensity-Modulated and Respiratory-Gated Radiotherapy Techniques for Pancreatic Carcinoma

    International Nuclear Information System (INIS)

    Purpose: To compare conformal radiotherapy (CRT), intensity-modulated radiotherapy (IMRT), and respiration-gated radiotherapy (RGRT) planning techniques for pancreatic cancer. All target volumes were determined using four-dimensional computed tomography scans (4D CT). Methods and Materials: The pancreatic tumor and enlarged regional lymph nodes were contoured on all 10 phases of a planning 4D CT scan for 10 patients, and the planning target volumes (PTVallphases) were generated. Three consecutive respiratory phases for RGRT delivery in both inspiration and expiration were identified, and the corresponding PTVs (PTVinspiration and PTVexpiration) and organ at risk volumes created. Treatment plans using CRT and IMRT, with and without RGRT, were created for each PTV. Results: Compared with the CRT plans, IMRT significantly reduced the mean volume of right kidney exposed to 20 Gy from 27.7% ± 17.7% to 16.0% ± 18.2% (standard deviation) (p < 0.01), but this was not achieved for the left kidney (11.1% ± 14.2% to 5.7% ± 6.5%; p = 0.1). The IMRT plans also reduced the mean gastric, hepatic, and small bowel doses (p < 0.01). No additional reductions in the dose to the kidneys or other organs at risk were seen when RGRT plans were combined with either CRT or IMRT, and the findings for RGRT in end-expiration and end-inspiration were similar. Conclusion: 4D CT-based IMRT plans for pancreatic tumors significantly reduced the radiation doses to the right kidney, liver, stomach, and small bowel compared with CRT plans. The additional dosimetric benefits from RGRT appear limited in this setting

  18. Comparison of IGRT Registration Strategies for Optimal Coverage of Primary Lung Tumors and Involved Nodes Based on Multiple Four-Dimensional CT Scans Obtained Throughout the Radiotherapy Course

    International Nuclear Information System (INIS)

    Purpose: To investigate the impact of primary tumor and involved lymph node (LN) geometry (centroid, shape, volume) on internal target volume (ITV) throughout treatment for locally advanced non–small cell lung cancer using weekly four-dimensional computed tomography (4DCT). Methods and Materials: Eleven patients with advanced non–small cell lung cancer were treated using image-guided radiotherapy with acquisition of weekly 10-Phase 4DCTs (n = 51). Initial ITV was based on planning 4DCT. Master-ITV incorporated target geometry across the entire treatment (all 4DCTs). Geographic miss was defined as the % Master-ITV positioned outside of the initial planning ITV after registration is complete. Registration strategies considered were bony (B), primary tumor soft tissue alone (T), and registration based on primary tumor and involved LNs (TLN). Results: The % geographic miss for the primary tumor, mediastinal, and hilar lymph nodes based on each registration strategy were (1) B: 30%, 30%, 30%; (2) T: 21%, 40%, 36%; and (3) TLN: 26%, 26%, 27%. Mean geographic expansions to encompass 100% of the primary tumor and involved LNs were 1.2 ± 0.7 cm and 0.8 ± 0.3 cm, respectively, for B and TLN. Primary and involved LN expansions were 0.7 ± 0.5 cm and 1.1 ± 0.5 cm for T. Conclusion: T is best for solitary targets. When treatments include primary tumor and LNs, B and TLN provide more comprehensive geographic coverage. We have identified high % geographic miss when considering multiple registration strategies. The dosimetric implications are the subject of future study.

  19. Comparison of Intensity-Modulated Radiotherapy Planning Based on Manual and Automatically Generated Contours Using Deformable Image Registration in Four-Dimensional Computed Tomography of Lung Cancer Patients

    International Nuclear Information System (INIS)

    Purpose: To evaluate the implications of differences between contours drawn manually and contours generated automatically by deformable image registration for four-dimensional (4D) treatment planning. Methods and Materials: In 12 lung cancer patients intensity-modulated radiotherapy (IMRT) planning was performed for both manual contours and automatically generated ('auto') contours in mid and peak expiration of 4D computed tomography scans, with the manual contours in peak inspiration serving as the reference for the displacement vector fields. Manual and auto plans were analyzed with respect to their coverage of the manual contours, which were assumed to represent the anatomically correct volumes. Results: Auto contours were on average larger than manual contours by up to 9%. Objective scores, D2% and D98% of the planning target volume, homogeneity and conformity indices, and coverage of normal tissue structures (lungs, heart, esophagus, spinal cord) at defined dose levels were not significantly different between plans (p = 0.22-0.94). Differences were statistically insignificant for the generalized equivalent uniform dose of the planning target volume (p = 0.19-0.94) and normal tissue complication probabilities for lung and esophagus (p = 0.13-0.47). Dosimetric differences >2% or >1 Gy were more frequent in patients with auto/manual volume differences ≥10% (p = 0.04). Conclusions: The applied deformable image registration algorithm produces clinically plausible auto contours in the majority of structures. At this stage clinical supervision of the auto contouring process is required, and manual interventions may become necessary. Before routine use, further investigations are required, particularly to reduce imaging artifacts

  20. Development of an ultrasmall C-band linear accelerator guide for a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head.

    Science.gov (United States)

    Kamino, Yuichiro; Miura, Sadao; Kokubo, Masaki; Yamashita, Ichiro; Hirai, Etsuro; Hiraoka, Masahiro; Ishikawa, Junzo

    2007-05-01

    We are developing a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head. It is capable of pursuing irradiation and delivering irradiation precisely with the help of an agile moving x-ray head on the gimbals. Requirements for the accelerator guide were established, system design was developed, and detailed design was conducted. An accelerator guide was manufactured and basic beam performance and leakage radiation from the accelerator guide were evaluated at a low pulse repetition rate. The accelerator guide including the electron gun is 38 cm long and weighs about 10 kg. The length of the accelerating structure is 24.4 cm. The accelerating structure is a standing wave type and is composed of the axial-coupled injector section and the side-coupled acceleration cavity section. The injector section is composed of one prebuncher cavity, one buncher cavity, one side-coupled half cavity, and two axial coupling cavities. The acceleration cavity section is composed of eight side-coupled nose reentrant cavities and eight coupling cavities. The electron gun is a diode-type gun with a cerium hexaboride (CeB6) direct heating cathode. The accelerator guide can be operated without any magnetic focusing device. Output beam current was 75 mA with a transmission efficiency of 58%, and the average energy was 5.24 MeV. Beam energy was distributed from 4.95 to 5.6 MeV. The beam profile, measured 88 mm from the beam output hole on the axis of the accelerator guide, was 0.7 mm X 0.9 mm full width at half maximum (FWHM) width. The beam loading line was 5.925 (MeV)-Ib (mA) X 0.00808 (MeV/mA), where Ib is output beam current. The maximum radiation leakage of the accelerator guide at 100 cm from the axis of the accelerator guide was calculated as 0.33 cGy/min at the rated x-ray output of 500 cGy/min from the measured value. This leakage requires no radiation shielding for the accelerator guide itself per IEC 60601-2-1. PMID:17555261

  1. Four-dimensional computed tomography based assessment and analysis of lung tumor motion during free-breathing respiration

    International Nuclear Information System (INIS)

    Objective: To quantify the amplitudes of lung tumor motion during free-breathing using four dimensional computed tomography (4DCT), and seek the characteristics of tumors with large motion. Methods: Respiratory-induced tumor motion was analyzed for 44 tumors from 43 patients. All patients un-derwent 4DCT during free-breathing before treatment. Gross tumor volumes (GTV) on ten respiratory phases were contoured by the same doctor. The centroids of GTVs were autoplaced with treatment software (ADAC Pinnacle 7.4f), then the amplitudes of tumor motion were assessed. The various clinical and anatomic factors associated with GTV motion were analyzed. The characteristics of tumors with motion greater than 5 mm in any direction were explored. Results: The tumor motion was found to be associated with T stage, GTV size, the superior-inferior (SI) tumor location in the lung, and the attachment to rigid structures such as the chest wall, vertebrae or mediastinum. The motion over 5 mm was observed in ten tumors, which were all located in the lower or posterior half of the lung, with the greatest motion of 14.4 mm. For 95% of the tumors, the magnitude of motion was less than I 1.8 mm, 4.6 mm and 2.7 mm along the SI, anterior-posterior (AP) and lateral directions, respectively. Conclusions: Tumor motion due to breathing is associated with tumor location, volume, and T stage. The greatest motion was in the SI direction for unfixed tumor in lower-lobe, followed by tumor in upper-lobe posterior-segment. (authors)

  2. The Four Dimensional Symptoms Questionnaire (4DSQ): A validation study of a multidimensional self-report questionnaire to assess distress, depression, anxiety and somatization

    OpenAIRE

    van Balkom Anton JLM; van Boeijen Christine A; Hermens Marleen LM; Penninx Brenda WJH; de Vet Henrica CW; Adèr Herman J; van Marwijk Harm WJ; Terluin Berend; van der Klink Jac JL; Stalman Wim AB

    2006-01-01

    Abstract Background The Four-Dimensional Symptom Questionnaire (4DSQ) is a self-report questionnaire that has been developed in primary care to distinguish non-specific general distress from depression, anxiety and somatization. The purpose of this paper is to evaluate its criterion and construct validity. Methods Data from 10 different primary care studies have been used. Criterion validity was assessed by comparing the 4DSQ scores with clinical diagnoses, the GPs' diagnosis of any psychosoc...

  3. Leadership as social identity management: Introducing the Identity Leadership Inventory (ILI) to assess and validate a four-dimensional model

    OpenAIRE

    Steffens, Niklas K; Haslam, S Alexander; Reicher, Stephen D.; Platow, Michael J; Fransen, Katrien; Yang, Jie; Ryan, Michelle K.; Jetten, Jolanda; Peters, Kim O.; Boen, Filip

    2014-01-01

    Although nearly two decades of research has provided support for the social identity approach to leadership, most previous work has focused on leaders’ identity prototypicality while neglecting the assessment of other equally important dimensions of social identity management. However, recent theoretical developments have argued that in order to mobilize and direct followers’ energies, leaders need not only to ‘be one of us’ (identity prototypicality), but also to ‘do it for us’ (identity adv...

  4. Four-Dimensional Computed Tomography Based Respiratory-Gated Radiotherapy with Respiratory Guidance System: Analysis of Respiratory Signals and Dosimetric Comparison

    OpenAIRE

    2014-01-01

    Purpose. To investigate the effectiveness of respiratory guidance system in 4-dimensional computed tomography (4DCT) based respiratory-gated radiation therapy (RGRT) by comparing respiratory signals and dosimetric analysis of treatment plans. Methods. The respiratory amplitude and period of the free, the audio device-guided, and the complex system-guided breathing were evaluated in eleven patients with lung or liver cancers. The dosimetric parameters were assessed by comparing free breathing ...

  5. Usefulness of four dimensional (4D) PET/CT imaging in the evaluation of thoracic lesions and in radiotherapy planning: Review of the literature.

    Science.gov (United States)

    Sindoni, Alessandro; Minutoli, Fabio; Pontoriero, Antonio; Iatì, Giuseppe; Baldari, Sergio; Pergolizzi, Stefano

    2016-06-01

    In the past decade, Positron Emission Tomography (PET) has become a routinely used methodology for the assessment of solid tumors, which can detect functional abnormalities even before they become morphologically evident on conventional imaging. PET imaging has been reported to be useful in characterizing solitary pulmonary nodules, guiding biopsy, improving lung cancer staging, guiding therapy, monitoring treatment response and predicting outcome. This review focuses on the most relevant and recent literature findings, highlighting the current role of PET/CT and the evaluation of 4D-PET/CT modality for radiation therapy planning applications. Current evidence suggests that gross tumor volume delineation based on 4D-PET/CT information may be the best approach currently available for its delineation in thoracic cancers (lung and non-lung lesions). In our opinion, its use in this clinical setting is strongly encouraged, as it may improve patient treatment outcome in the setting of radiation therapy for cancers of the thoracic region, not only involving lung, but also lymph nodes and esophageal tissue. Literature results warrants further investigation in future prospective studies, especially in the setting of dose escalation. PMID:27133755

  6. Four-dimensional computed tomography: a method of assessing right ventricular outflow tract and pulmonary artery deformations throughout the cardiac cycle

    Energy Technology Data Exchange (ETDEWEB)

    Schievano, Silvia; Capelli, Claudio; Young, Carol; Lurz, Philipp; Nordmeyer, Johannes; Owens, Catherine; Bonhoeffer, Philipp; Taylor, Andrew M. [UCL, Institute of Child Health and Great, Ormond Street Hospital for Children, Cardiovascular Unit, London (United Kingdom)

    2011-01-15

    To characterise 3D deformations of the right ventricular outflow tract (RVOT)/ pulmonary arteries (PAs) during the cardiac cycle and estimate the errors of conventional 2D assessments. Contrast-enhanced, ECG-gated cardiovascular computed tomography (CT) findings were retrospectively analysed from 12 patients. The acquisition of 3D images over 10 phases of the cardiac cycle created a four-dimensional CT (4DCT) dataset. The datasets were reconstructed and deformation measured at various levels of the RVOT/PAs in both space and time. Section planes were either static or dynamic relative to the motion of the structures. 4DCT enabled measurement and characterisation of in vivo 3D changes of patients' RVOT/PA during the cardiac cycle. The studied patient population showed a wide range of RVOT/PA morphologies, sizes and dynamics that develop late after surgical repair of congenital heart disease. There were also significant differences in the measured cross-sectional areas of the structures between static and dynamic section planes (up to 150%, p < 0.05) secondary to large 3D displacements and rotations. 4DCT imaging data suggest high variability in RVOT/PA dynamics and significant errors in deformation measurements if 3D analysis is not carried out. These findings play an important role for the development of novel percutaneous approaches to pulmonary valve intervention. (orig.)

  7. The Four-Dimensional Symptom Questionnaire (4DSQ: a validation study of a multidimensional self-report questionnaire to assess distress, depression, anxiety and somatization

    Directory of Open Access Journals (Sweden)

    van Balkom Anton JLM

    2006-08-01

    Full Text Available Abstract Background The Four-Dimensional Symptom Questionnaire (4DSQ is a self-report questionnaire that has been developed in primary care to distinguish non-specific general distress from depression, anxiety and somatization. The purpose of this paper is to evaluate its criterion and construct validity. Methods Data from 10 different primary care studies have been used. Criterion validity was assessed by comparing the 4DSQ scores with clinical diagnoses, the GPs' diagnosis of any psychosocial problem for Distress, standardised psychiatric diagnoses for Depression and Anxiety, and GPs' suspicion of somatization for Somatization. ROC analyses and logistic regression analyses were used to examine the associations. Construct validity was evaluated by investigating the inter-correlations between the scales, the factorial structure, the associations with other symptom questionnaires, and the associations with stress, personality and social functioning. The factorial structure of the 4DSQ was assessed through confirmatory factor analysis (CFA. The associations with other questionnaires were assessed with Pearson correlations and regression analyses. Results Regarding criterion validity, the Distress scale was associated with any psychosocial diagnosis (area under the ROC curve [AUC] 0.79, the Depression scale was associated with major depression (AUC = 0.83, the Anxiety scale was associated with anxiety disorder (AUC = 0.66, and the Somatization scale was associated with the GPs' suspicion of somatization (AUC = 0.65. Regarding the construct validity, the 4DSQ scales appeared to have considerable inter-correlations (r = 0.35-0.71. However, 30–40% of the variance of each scale was unique for that scale. CFA confirmed the 4-factor structure with a comparative fit index (CFI of 0.92. The 4DSQ scales correlated with most other questionnaires measuring corresponding constructs. However, the 4DSQ Distress scale appeared to correlate with some other

  8. Prostate displacement during transabdominal ultrasound image-guided radiotherapy assessed by real-time four-dimensional transperineal monitoring

    DEFF Research Database (Denmark)

    Baker, Mariwan; Behrens, Claus F.

    2015-01-01

    values ( 1 SD) (mm); inferior ( )-superior (I/S): (0.1 0.8); left ( )-right (L/R): (0.2 0.7); and anterior ( )-posterior (A/P): (0.1 1.0). The majority of the displacements were within 1 – 2 mm. Only two scans (5%) (A/P direction) and 16% of Euclidean distances were larger than 2.0 mm. The largest...

  9. Assessment of gross tumor volume motion and the influence factors during respiration for lung cancer using four-dimensional computed tomography

    International Nuclear Information System (INIS)

    Objective: This study was to assess the three-dimensional gross tumor volume(GTV) motion of lung cancer caused by respiration using four-dimensional computed tomography (4DCT), and to analyze the influence factors. Methods: Four-DCT scans of 22 lung focuses in 21 patients with lung cancer were analyzed. The gross tumor volume was contoured in all 10 respiration phases of 4DCT scans. The changes in volume of GTV, the 3D motion of the centroid,boundary of GTV and the 3D spatial motion vectors were calculated and the influence factors were analyzed. Results: The average change in volume of GTV was + 14.3%(0.2%-42.5%)/-8.4% (0.4%-38.6%), the average movement amplitude of GTV centroid and GTV boundary were (0.18±0.12)cm, (0.20±0.16)cm, (0.53±0.59)cm and (0.42±0.23)cm, (0.41±0.22)cm, (0.57±0.70)cm in medio-lateral, vertro-dorsal, cranio-caudal (CC) direction, respectively. The CC movement was larger than other directions (Z=-2.12, P=0.034; Z:-2.10, P=0.035), and no significant difference was observed in 3D motion of GTV boundary (Z=-0.81, P=0.417; Z=-0.86, 0.391). The CC motion of GTV centroid in lower lobe was larger than that in upper lobe [(0.87±0.64) and (0.35±0.49)cm, (t=-2.12, P=0.047)], and no significant difference was found in other directions [(0.23±0.10) and (0.19±0.18)cm (t=-0.49, P=0.629), (0.21±0.13) and (0.17±0.11)cm (t=0.76, P=0.460)]. There was no correlation of the 3D movement and 3D spatial motion vector of GTV to the volume of GTV (r=-0.306, -0.062, -0.279, -0.300; P=0.189, 0.796, 0.234, 0.199). Conclusions: GTV motion of patients with lung cancer is individual, the CC movement is the moat obvious, using 4DCT to assess is comparatively accurate. The motion amplitude of lower lobe focuses is larger. No significant correlation of the GTV motion to the volume was observed. Larger sample study is needed to analyze the influence of adjacency to the GTV motion. (authors)

  10. Contact radiotherapy. Report of technological assessment

    International Nuclear Information System (INIS)

    This report aims at assessing safety, indications, the role in therapeutic strategy, and efficiency of contact radiotherapy. It also aims at answering questions like: is the contact radiotherapy technique validated? What are the indications for contact radiotherapy? What about the efficiency and safety of contact radiotherapy? After a presentation of preliminary notions on radiotherapy (radiation types, dose, and irradiation techniques), the report presents this specific technique of contact radiotherapy: definition, devices, use recommendations, issues of radiation protection, modalities of performance of a contact radiotherapy session, and concerned pathologies. Then, based on a literature survey, this report addresses the various concerned tumours (skin, rectum, brain, breast), indicates some general information about these tumours (epidemiological data, anatomy and classification, therapeutic options, radiotherapy), and proposes an assessment of the efficiency and safety of contact radiotherapy

  11. Investigation of pancreas tumour movements and of their potential markers by four-dimensional scanography: implication for image-guided radiotherapy; etude des mouvements des tumeurs du pancreas et de leurs marqueurs potentiels par scanographie quadridimensionnelle: implication pour la radiotherapie guidee par l'image

    Energy Technology Data Exchange (ETDEWEB)

    Huguet, F. [Hopital Tenon, Paris (France); Yorke, E.; Davidson, M.; Zhang, Z.; Jackson, A.; Mageras, G.; Wu, A.; Goodman, K. [Memorial Sloan-Kettering Cancer Center, New York (United States)

    2011-10-15

    The authors report the study which aimed at quantifying pancreas tumour movements induced by breathing by using four-dimensional scanography, and at assessing the reliability of biliary prosthesis, of intra-tumor fiducials, and of an external maker as position markers of the gross tumour volume (GTV). The authors analyzed scanography images acquired during the simulation of 22 patients treated for locally advanced pancreas cancer by intensity-modulated conformational irradiation with respiratory gating. Average movements in different directions have measured. Respiratory gating limits the GTV movement amplitude by 40 to 60 per cent. GTV movements are in good correlation with that of biliary prostheses and intra-tumor fiducials. Short communication

  12. Spinors in Four-Dimensional Spaces

    CERN Document Server

    Torres del Castillo, Gerardo F

    2010-01-01

    Without using the customary Clifford algebras frequently studied in connection with the representations of orthogonal groups, this book gives an elementary introduction to the two-component spinor formalism for four-dimensional spaces with any signature. Some of the useful applications of four-dimensional spinors, such as Yang–Mills theory, are derived in detail using illustrative examples. Key topics and features: • Uniform treatment of the spinor formalism for four-dimensional spaces of any signature, not only the usual signature (+ + + −) employed in relativity • Examples taken from Riemannian geometry and special or general relativity are discussed in detail, emphasizing the usefulness of the two-component spinor formalism • Exercises in each chapter • The relationship of Clifford algebras and Dirac four-component spinors is established • Applications of the two-component formalism, focusing mainly on general relativity, are presented in the context of actual computations Spinors in Four-Dim...

  13. Cohomology of real four-dimensional triquadrics

    Science.gov (United States)

    Krasnov, Vyacheslav A.

    2012-10-01

    We consider non-singular intersections of three real six-dimensional quadrics. They are referred to for brevity as real four-dimensional triquadrics. We calculate the dimensions of their cohomology spaces with coefficients in the field of two elements.

  14. String breaking in four dimensional lattice QCD

    International Nuclear Information System (INIS)

    Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on a 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse [but O(a2) improved] lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R∼>1 fm

  15. String Breaking in Four Dimensional Lattice QCD

    CERN Document Server

    Duncan, A; Thacker, H

    2001-01-01

    Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on an Athlon 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse (but O($a^2$) improved) lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R $\\geq$ approximately 1 fm.

  16. Purley four-dimensional viable anomaly mediation

    International Nuclear Information System (INIS)

    Anomaly mediation of supersymmetry breaking solves the supersymmetric flavor problem thanks to its ultraviolet-insensitivity. However, it suffers from two problems: sleptons have negative masses-squared, and there are likely bulk moduli that spoil the framework. Here, we present the first fully ultraviolet-insensitive model of anomaly mediation with positive slepton masses-squared in a purely four-dimensional framework. Our model is based on the additional D-term contributions to the sparticle masses, and the conformal sequestering mechanism. (author)

  17. Dynamic ventilation imaging from four-dimensional computed tomography

    Science.gov (United States)

    Guerrero, Thomas; Sanders, Kevin; Castillo, Edward; Zhang, Yin; Bidaut, Luc; Pan, Tinsu; Komaki, Ritsuko

    2006-02-01

    A novel method for dynamic ventilation imaging of the full respiratory cycle from four-dimensional computed tomography (4D CT) acquired without added contrast is presented. Three cases with 4D CT images obtained with respiratory gated acquisition for radiotherapy treatment planning were selected. Each of the 4D CT data sets was acquired during resting tidal breathing. A deformable image registration algorithm mapped each (voxel) corresponding tissue element across the 4D CT data set. From local average CT values, the change in fraction of air per voxel (i.e. local ventilation) was calculated. A 4D ventilation image set was calculated using pairs formed with the maximum expiration image volume, first the exhalation then the inhalation phases representing a complete breath cycle. A preliminary validation using manually determined lung volumes was performed. The calculated total ventilation was compared to the change in contoured lung volumes between the CT pairs (measured volume). A linear regression resulted in a slope of 1.01 and a correlation coefficient of 0.984 for the ventilation images. The spatial distribution of ventilation was found to be case specific and a 30% difference in mass-specific ventilation between the lower and upper lung halves was found. These images may be useful in radiotherapy planning.

  18. Dynamic ventilation imaging from four-dimensional computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, Thomas [Division of Radiation Oncology, University of Texas M D Anderson Cancer Center, Houston, TX 77030-4009 (United States); Sanders, Kevin [Division of Radiation Oncology, University of Texas M D Anderson Cancer Center, Houston, TX 77030-4009 (United States); Castillo, Edward [Department of Computational and Applied Mathematics, Rice University, Houston, TX (United States); Zhang Yin [Department of Computational and Applied Mathematics, Rice University, Houston, TX (United States); Bidaut, Luc [Division of Diagnostic Imaging, University of Texas M D Anderson Cancer Center, Houston, TX (United States); Pan Tinsu [Division of Diagnostic Imaging, University of Texas M D Anderson Cancer Center, Houston, TX (United States); Komaki, Ritsuko [Division of Radiation Oncology, University of Texas M D Anderson Cancer Center, Houston, TX 77030-4009 (United States)

    2006-02-21

    A novel method for dynamic ventilation imaging of the full respiratory cycle from four-dimensional computed tomography (4D CT) acquired without added contrast is presented. Three cases with 4D CT images obtained with respiratory gated acquisition for radiotherapy treatment planning were selected. Each of the 4D CT data sets was acquired during resting tidal breathing. A deformable image registration algorithm mapped each (voxel) corresponding tissue element across the 4D CT data set. From local average CT values, the change in fraction of air per voxel (i.e. local ventilation) was calculated. A 4D ventilation image set was calculated using pairs formed with the maximum expiration image volume, first the exhalation then the inhalation phases representing a complete breath cycle. A preliminary validation using manually determined lung volumes was performed. The calculated total ventilation was compared to the change in contoured lung volumes between the CT pairs (measured volume). A linear regression resulted in a slope of 1.01 and a correlation coefficient of 0.984 for the ventilation images. The spatial distribution of ventilation was found to be case specific and a 30% difference in mass-specific ventilation between the lower and upper lung halves was found. These images may be useful in radiotherapy planning.

  19. Quantum teleportation of four-dimensional qudits

    International Nuclear Information System (INIS)

    A protocol for the teleportation of arbitrary quantum states of four-dimensional qudits is presented. The qudit to be teleported is encoded in the combined state of two ensembles of atoms placed in a cavity at the sender's side. The receiver uses a similar setup, with his atoms prepared in a particular initial state. The teleportation protocol then consists of adiabatic mapping of the ensemble states onto photonic degrees of freedom, which are then directed onto a specific beam splitter and detection setup. For part of the measurement outcome, the qudit state is fully transferred to the receiver. Other detection events lead to partial teleportation or failed teleportation attempts. The interpretation of the different detection outcomes and possible ways of improving the full teleportation probability are discussed.

  20. Four-dimensional unsubtraction with massive particles

    CERN Document Server

    Sborlini, German F R; Rodrigo, German

    2016-01-01

    We extend the four-dimensional unsubtraction method, which is based on the loop-tree duality (LTD), to deal with processes involving heavy particles. The method allows to perform the summation over degenerate IR configurations directly at integrand level in such a way that NLO corrections can be implemented directly in four space-time dimensions. We define a general momentum mapping between the real and virtual kinematics that accounts properly for the quasi-collinear configurations, and leads to an smooth massless limit. We illustrate the method first with an scalar toy example, and then analyse the case of the decay of a scalar or vector boson into a pair of massive quarks. The results presented in this paper are suitable for the application of the method to any multipartonic process.

  1. N=3 four dimensional field theories

    CERN Document Server

    García-Etxebarria, Iñaki

    2015-01-01

    We introduce a class of four dimensional field theories constructed by quotienting ordinary $\\mathcal{N}=4$ $U(N)$ SYM by particular combinations of R-symmetry and $SL(2,\\mathbb{Z})$ automorphisms. These theories appear naturally on the worldvolume of D3 branes probing terminal singularities in F-theory, where they can be thought of as non-perturbative generalizations of the O3 plane. We focus on cases preserving only 12 supercharges, where the quotient gives rise to theories with coupling fixed at a value of order one. These constructions posses an unconventional large $N$ limit described by a non-trivial F-theory fibration with base $AdS_5\\times (S^5/\\mathbb{Z}_k)$. Upon reduction on a circle the $\\mathcal{N}=3$ theories flow to well-known $\\mathcal{N}=6$ ABJM theories.

  2. Four-dimensional computed tomography angiographic evaluation of cranial dural arteriovenous fistula before and after embolization

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Bing, E-mail: bing.tian@hotmail.com; Xu, Bing, E-mail: aishanli0102@126.com; Lu, Jianping, E-mail: tianbing2003@163.com; Liu, Qi, E-mail: liuqimd@126.com; Wang, Li, E-mail: wangli_changhai@163.com; Wang, Minjie, E-mail: cjr.wangminjie@vip.163.com

    2015-06-15

    Highlights: • 4D CTA showed excellent agreement with DSA with regard to identification of feeding arteries and drainage veins. • The most important finding was 4D CTA in determining the impact of DAVF treatment with transarterial embolization. • 4D CTA provides images similar to those obtained with DSA both before and after treatment. - Abstract: Purpose: This study aimed to evaluate the usefulness of four-dimensional CTA before and after embolization treatment with ONYX-18 in eleven patients with cranial dural arteriovenous fistulas, and to compare the results with those of the reference standard DSA. Patients and Methods: Eleven patients with cranial dural arteriovenous fistulas detected on DSA underwent transarterial embolization with ONYX-18. Four-dimensional CTA was performed an average of 2 days before and 4 days after DSA. Four-dimensional CTA and DSA images were reviewed by two neuroradiologists for identification of feeding arteries and drainage veins and for determining treatment effects. Interobserver and intermodality agreement between four-dimensional CTA and DSA were assessed. Results: Forty-two feeding arteries were identified for 14 fistulas in the 11 patients. Of these, 36 (85.71%) were detected on four-dimensional CTA. After transarterial embolization, one patient got partly embolized, and the fistulas in the remaining 10 patients were completely occluded. The interobserver agreement for four-dimensional CTA and intermodality agreement between four-dimensional CTA and DSA were excellent (κ = 1) for shunt location, identification of drainage veins, and fistula occlusion after treatment. Conclusion: Four-dimensional CTA images are highly accurate when compared with DSA images both before and after transarterial embolization treatment. Four-dimensional CTA can be used for diagnosis as well as follow-up of cranial dural arteriovenous fistulas in clinical settings.

  3. Four-dimensional computed tomography angiographic evaluation of cranial dural arteriovenous fistula before and after embolization

    International Nuclear Information System (INIS)

    Highlights: • 4D CTA showed excellent agreement with DSA with regard to identification of feeding arteries and drainage veins. • The most important finding was 4D CTA in determining the impact of DAVF treatment with transarterial embolization. • 4D CTA provides images similar to those obtained with DSA both before and after treatment. - Abstract: Purpose: This study aimed to evaluate the usefulness of four-dimensional CTA before and after embolization treatment with ONYX-18 in eleven patients with cranial dural arteriovenous fistulas, and to compare the results with those of the reference standard DSA. Patients and Methods: Eleven patients with cranial dural arteriovenous fistulas detected on DSA underwent transarterial embolization with ONYX-18. Four-dimensional CTA was performed an average of 2 days before and 4 days after DSA. Four-dimensional CTA and DSA images were reviewed by two neuroradiologists for identification of feeding arteries and drainage veins and for determining treatment effects. Interobserver and intermodality agreement between four-dimensional CTA and DSA were assessed. Results: Forty-two feeding arteries were identified for 14 fistulas in the 11 patients. Of these, 36 (85.71%) were detected on four-dimensional CTA. After transarterial embolization, one patient got partly embolized, and the fistulas in the remaining 10 patients were completely occluded. The interobserver agreement for four-dimensional CTA and intermodality agreement between four-dimensional CTA and DSA were excellent (κ = 1) for shunt location, identification of drainage veins, and fistula occlusion after treatment. Conclusion: Four-dimensional CTA images are highly accurate when compared with DSA images both before and after transarterial embolization treatment. Four-dimensional CTA can be used for diagnosis as well as follow-up of cranial dural arteriovenous fistulas in clinical settings

  4. General flat four-dimensional world pictures and clock systems

    Science.gov (United States)

    Hsu, J. P.; Underwood, J. A.

    1978-01-01

    We explore the mathematical structure and the physical implications of a general four-dimensional symmetry framework which is consistent with the Poincare-Einstein principle of relativity for physical laws and with experiments. In particular, we discuss a four-dimensional framework in which all observers in different frames use one and the same grid of clocks. The general framework includes special relativity and a recently proposed new four-dimensional symmetry with a nonuniversal light speed as two special simple cases. The connection between the properties of light propagation and the convention concerning clock systems is also discussed, and is seen to be nonunique within the four-dimensional framework.

  5. Assessment of psychological responses in patients about to receive radiotherapy

    International Nuclear Information System (INIS)

    Radiotherapy is considered to be associated with psychological distress. We assessed the mental status, anxiety, and the factors associated with these in cancer patients about to receive radiotherapy. Hospitalized patients about to receive radiotherapy participated. Psychological status was assessed by a psychiatrist, based on interview about the type of anxiety related to cancer or radiotherapy as well as self-rating questionnaires. Eligible data were collected from 94 patients. The incidence of mental disorders was 20%. The total mood disturbance scores were significantly higher in patients with poor performance status. The most common type of anxiety regarding radiotherapy was acute adverse effect, and the predictors were palliative treatment and living alone. Mental disorders, mood disturbance, and anxiety in patients cannot be neglected in radiation oncology practice. Especially careful attention should be paid to patients with these predictive factors. (author)

  6. On the four-dimensional formulation of dimensionally regulated amplitudes

    Science.gov (United States)

    Fazio, A. R.; Mastrolia, P.; Mirabella, E.; Torres Bobadilla, W. J.

    2014-12-01

    Elaborating on the four-dimensional helicity scheme, we propose a pure four-dimensional formulation (FDF) of the -dimensional regularization of one-loop scattering amplitudes. In our formulation particles propagating inside the loop are represented by massive internal states regulating the divergences. The latter obey Feynman rules containing multiplicative selection rules which automatically account for the effects of the extra-dimensional regulating terms of the amplitude. We present explicit representations of the polarization and helicity states of the four-dimensional particles propagating in the loop. They allow for a complete, four-dimensional, unitarity-based construction of -dimensional amplitudes. Generalized unitarity within the FDF does not require any higher-dimensional extension of the Clifford and the spinor algebra. Finally we show how the FDF allows for the recursive construction of -dimensional one-loop integrands, generalizing the four-dimensional open-loop approach.

  7. On the Four-Dimensional Formulation of Dimensionally Regulated Amplitudes

    CERN Document Server

    Fazio, Raffaele A; Mirabella, Edoardo; Bobadilla, William J Torres

    2014-01-01

    We propose a pure four-dimensional formulation (FDF) of the d-dimensional regularization of one-loop scattering amplitudes. In our formulation particles propagating inside the loop are represented by massive internal states regulating the divergences. The latter obey Feynman rules containing multiplicative selection rules which automatically account for the effects of the extra-dimensional regulating terms of the amplitude. The equivalence between the FDF and the Four Dimensional Helicity scheme is discussed. We present explicit representations of the polarization and helicity states of the four-dimensional particles propagating in the loop. They allow for a complete, four-dimensional, unitarity-based construction of d-dimensional amplitudes. Generalized unitarity within the FDF does not require any higher-dimensional extension of the Clifford and the spinor algebra. Finally we show how the FDF allows for the recursive construction of $d$-dimensional one-loop integrands, generalizing the four-dimensional open...

  8. On the four-dimensional formulation of dimensionally regulated amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Fazio, A.R. [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Mastrolia, P. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); Max-Planck-Institut fuer Physik, Munich (Germany); INFN, Padova (Italy); Mirabella, E. [Max-Planck-Institut fuer Physik, Munich (Germany); Torres Bobadilla, W.J. [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Universita di Padova, Dipartimento di Fisica e Astronomia, Padua (Italy); INFN, Padova (Italy)

    2014-12-01

    Elaborating on the four-dimensional helicity scheme, we propose a pure four-dimensional formulation (FDF) of the d-dimensional regularization of one-loop scattering amplitudes. In our formulation particles propagating inside the loop are represented by massive internal states regulating the divergences. The latter obey Feynman rules containing multiplicative selection rules which automatically account for the effects of the extra-dimensional regulating terms of the amplitude. We present explicit representations of the polarization and helicity states of the four-dimensional particles propagating in the loop. They allow for a complete, four-dimensional, unitarity-based construction of d-dimensional amplitudes. Generalized unitarity within the FDF does not require any higher-dimensional extension of the Clifford and the spinor algebra. Finally we show how the FDF allows for the recursive construction of d-dimensional one-loop integrands, generalizing the four-dimensional open-loop approach. (orig.)

  9. Statistical Entropy of Four-Dimensional Extremal Black Holes

    OpenAIRE

    Maldacena, Juan; Strominger, Andrew

    1996-01-01

    String theory is used to count microstates of four-dimensional extremal black holes in compactifications with $N=4$ and $N=8$ supersymmetry. The result agrees for large charges with the Bekenstein-Hawking entropy.

  10. Commutative curvature operators over four-dimensional generalized symmetric

    Directory of Open Access Journals (Sweden)

    Ali Haji-Badali

    2014-12-01

    Full Text Available Commutative properties of four-dimensional generalized symmetric pseudo-Riemannian manifolds were considered. Specially, in this paper, we studied Skew-Tsankov and Jacobi-Tsankov conditions in 4-dimensional pseudo-Riemannian generalized symmetric manifolds.

  11. A four-dimensional petroleum systems model for the San Joaquin Basin Province, California: Chapter 12 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

    Science.gov (United States)

    Peters, Kenneth E.; Magoon, Leslie B.; Lampe, Carolyn; Scheirer, Allegra Hosford; Lillis, Paul G.; Gautier, Donald L.

    2008-01-01

    A calibrated numerical model depicts the geometry and three-dimensional (3-D) evolution of petroleum systems through time (4-D) in a 249 x 309 km (155 x 192 mi) area covering all of the San Joaquin Basin Province of California. Model input includes 3-D structural and stratigraphic data for key horizons and maps of unit thickness, lithology, paleobathymetry, heat flow, original total organic carbon, and original Rock-Eval pyrolysis hydrogen index for each source rock. The four principal petroleum source rocks in the basin are the Miocene Antelope shale of Graham and Williams (1985; hereafter referred to as Antelope shale), the Eocene Kreyenhagen Formation, the Eocene Tumey formation of Atwill (1935; hereafter referred to as Tumey formation), and the Cretaceous to Paleocene Moreno Formation. Due to limited Rock-Eval/total organic carbon data, the Tumey formation was modeled using constant values of original total organic carbon and original hydrogen index. Maps of original total organic carbon and original hydrogen index were created for the other three source rocks. The Antelope shale was modeled using Type IIS kerogen kinetics, whereas Type II kinetics were used for the other source rocks. Four-dimensional modeling and geologic field evidence indicate that maximum burial of the three principal Cenozoic source rocks occurred in latest Pliocene to Holocene time. For example, a 1-D extraction of burial history from the 4-D model in the Tejon depocenter shows that the bottom of the Antelope shale source rock began expulsion (10 percent transformation ratio) about 4.6 Ma and reached peak expulsion (50 percent transformation ratio) about 3.6 Ma. Except on the west flank of the basin, where steep dips in outcrop and seismic data indicate substantial uplift, little or no section has been eroded. Most petroleum migration occurred during late Cenozoic time in distinct stratigraphic intervals along east-west pathways from pods of active petroleum source rock in the Tejon and

  12. Quality assurance of radiotherapy and its clinical assessment

    International Nuclear Information System (INIS)

    We investigated the clinical quality assurance (QA) of radiotherapy in Japan since 1981. The aim of this study was to establish the QA of a radiotherapy system and its clinical assessment in Japan. We introduced the Patterns of Care Study (PCS) into Japan to perform this study in 1996. The PCS is a retrospective study designed to establish the national practice for cancer patients during a specific period and should be a complementary study to a prospective randomized controlled study. We collected precise data for 4399 patients with carcinomas of the breast, cervix, esophagus, lung and prostate by means of external audits for 96 institutes from 1998 through 2001. Patients were randomly sampled with two-stage cluster sampling. We stratified 556 institutes into four categories according to the academic condition and annual number of radiotherapy patients. National and regional averages of various factors of radiotherapy could be calculated and were used to measure QA of radiotherapy. Using a standard score, we could compare the process of individual institutions with national averages and feed back the evaluation score to each institution. With a PCS process survey, we could observe the dissemination of the treatment method under evidence-based medicine from the prospective randomized controlled study. We proposed future prediction of the number of radiotherapy patients and a counter plan for equipment and personnel. The first US-Japan PCS Workshop was held at San Francisco in 2001. We could establish QA of a radiotherapy system using PCS 1995-97 in Japan. (author)

  13. Motion artifact detection in four-dimensional computed tomography images

    Science.gov (United States)

    Bouilhol, G.; Ayadi, M.; Pinho, R.; Rit, S.; Sarrut, D.

    2014-03-01

    Motion artifacts appear in four-dimensional computed tomography (4DCT) images because of suboptimal acquisition parameters or patient breathing irregularities. Frequency of motion artifacts is high and they may introduce errors in radiation therapy treatment planning. Motion artifact detection can be useful for image quality assessment and 4D reconstruction improvement but manual detection in many images is a tedious process. We propose a novel method to evaluate the quality of 4DCT images by automatic detection of motion artifacts. The method was used to evaluate the impact of the optimization of acquisition parameters on image quality at our institute. 4DCT images of 114 lung cancer patients were analyzed. Acquisitions were performed with a rotation period of 0.5 seconds and a pitch of 0.1 (74 patients) or 0.081 (40 patients). A sensitivity of 0.70 and a specificity of 0.97 were observed. End-exhale phases were less prone to motion artifacts. In phases where motion speed is high, the number of detected artifacts was systematically reduced with a pitch of 0.081 instead of 0.1 and the mean reduction was 0.79. The increase of the number of patients with no artifact detected was statistically significant for the 10%, 70% and 80% respiratory phases, indicating a substantial image quality improvement.

  14. Treatment assessment of radiotherapy using MR functional quantitative imaging

    Institute of Scientific and Technical Information of China (English)

    Zheng; Chang; Chunhao; Wang

    2015-01-01

    Recent developments in magnetic resonance(MR) functional quantitative imaging have made it a potentially powerful tool to assess treatment response in radiation therapy. With its abilities to capture functional information on underlying tissue characteristics, MR functional quantitative imaging can be valuable in assessing treatment response and as such to optimize therapeutic outcome. Various MR quantitative imaging techniques, including diffusion weighted imaging, diffusion tensor imaging, MR spectroscopy and dynamic contrastenhanced imaging, have been investigated and found useful for assessment of radiotherapy. However, various aspects including data reproducibility, interpretation of biomarkers, image quality and data analysis impose challenges on applications of MR functional quantitative imaging in radiotherapy assessment. All of these challenging issues shall be addressed to help us understand whether MR functional quantitative imaging is truly beneficial and contributes to future development of radiotherapy. It is evident that individualized therapy is the future direction of patient care. MR functional quantitative imaging might serves as an indispensable tool towards this promising direction.

  15. Utility of Four-Dimensional Computed Tomography for Analysis of Intrafractional and Interfractional Variation in Lung Volumes

    International Nuclear Information System (INIS)

    Purpose: To assess the viability of four-dimensional (4D) computed tomography (CT) in describing intrafractional and interfractional changes in lung volumes and to determine which breathing phase, if any, produces the most highly reproducible lung volumes among fractions. Methods and Materials: Weekly 4D CT scans were acquired for 13 patients with non-small-cell lung cancer during a course of radiotherapy. Contours delineating the right lung, left lung, and total lung were obtained by adapting library models of the anatomic structures to the CT images and propagating them to all 10 respiratory phases represented in the 4D CT image data set. Lung volumes were calculated using software tools in a commercial radiation treatment-planning system and analyzed for interfractional volume reproducibility using t tests and for phase reproducibility using a phase-dependent uncertainty curve across all patients. Probability (p) values of <0.05 were considered to indicate significant differences in all comparisons. Results: The average mean coefficient of variation of tidal volume across all patients was 25.0%. The average standard deviation of tidal volumes was 5.7% relative to the lung volume at end-expiration. Total volumes measured at the 30% phase were 15% more consistent than those measured at end-inspiration (p = 0.03). Conclusions: Four-dimensional CT assesses lung volume with acceptable precision; but the technique was unable to accurately predict interfractional changes in lung volume because wide variations in intra- and interfractional breathing cause high uncertainties in 4D CT data acquisition. The most reproducible breathing phase seems to be at the 30-40% phase (just before end-expiration)

  16. Radiotherapy

    International Nuclear Information System (INIS)

    This review highlights developments over the past decade in radiotherapy and attempts to summarize the state of the art in the management of the major diseases in which radiotherapy has a meaningful role. The equipment, radiobiology of radiotherapy and carcinoma of the lung, breast and intestines are highlighted

  17. Vector particles tunneling from four-dimensional Schwarzschild black holes

    Science.gov (United States)

    Chen, Ge-Rui; Zhou, Shiwei; Huang, Yong-Chang

    2015-05-01

    Vector particles' Hawking radiation from a four-dimensional Schwarzschild black hole is investigated. By applying the WKB approximation and the Hamilton-Jacobi ansatz to the Proca equation, we obtain the tunneling spectrum of vector particles and the expected Hawking temperature.

  18. Statistical Entropy of Four-Dimensional Extremal Black Holes

    International Nuclear Information System (INIS)

    String theory is used to count microstates of four-dimensional extremal black holes in compactifications with N=4 and N=8 supersymmetry. The result agrees for large charges with the Bekenstein-Hawking entropy. copyright 1996 The American Physical Society

  19. Lattice classification of the four-dimensional heterotic strings

    International Nuclear Information System (INIS)

    A lattice slicing procedure is proposed which leads to the classification of all four-dimensional chiral heterotic strings based on Conway and Sloane's 22-dimensional self-dual Euclidean lattices. By reversing this procedure it is possible to construct all these theories. (author)

  20. Four-dimensional conformal field theory using quaternions

    CERN Document Server

    Giardino, Sergio

    2015-01-01

    We build a four-dimensional quaternion-parametrized conformal field theory (QCFT) using quaternion holomorphic functions as the generators of quaternionic conformal transformations. Taking the two-dimensional complex-parametrized conformal field theory (CCFT) as our model, we study the stress tensor, the conserved charge, the symmetry generators, the quantization conditions and several operator product expansions (OPE's). Future applications also are addressed.

  1. A linear solution to the effective four-dimensionality problem

    OpenAIRE

    Trifonov, Vladimir

    2003-01-01

    In this note we formalize certain aspects of observation process in an attempt to link the logic of the observer with properties of the observables structures. It is shown that an observer with Boolean logic perceives her environment as a four-dimensional Lorentzian manifold.

  2. Multipole expansions in four-dimensional hyperspherical harmonics

    International Nuclear Information System (INIS)

    The technique of vector differentiation is applied to the problem of the derivation of multipole expansions in four-dimensional space. Explicit expressions for the multipole expansion of the function rnCj(r-circumflex) with r = r1 + r2 are given in terms of tensor products of two hyperspherical harmonics depending on the unit vectors r-circumflex1 and r-circumflex2. The multipole decomposition of the function (r1 . r2)n is also derived. The proposed method can be easily generalized to the case of the space with dimensionality larger than four. Several explicit expressions for the four-dimensional Clebsch-Gordan coefficients with particular values of parameters are presented in the closed form

  3. Four-dimensional pseudo-Riemannian homogeneous Ricci solitons

    OpenAIRE

    Calvaruso, Giovanni; Fino, Anna

    2011-01-01

    We consider four-dimensional homogeneous pseudo-Riemannian manifolds with non-trivial isotropy and completely classify the cases giving rise to non-trivial homogeneous Ricci solitons. In particular, we show the existence of non-compact homogeneous (and also invariant) pseudo-Riemannian Ricci solitons which are not isometric to solvmanifolds, and of conformally flat homogeneous pseudo-Riemannian Ricci solitons which are not symmetric.

  4. Mathieu moonshine in four dimensional N=1 theories

    International Nuclear Information System (INIS)

    We show that the recently discovered Mathieu moonshine plays a role for certain four dimensional theories with N=1 supersymmetry. These theories are obtained from the E8×E8 heterotic string theory by compactifying on toroidal orbifolds. We find that a universal contribution to the holomorphic gauge kinetic function can be expanded in such a way that the expansion coefficients are the dimensions of representations of the Mathieu group M24

  5. The transfer matrix in four dimensional causal dynamical triangulations

    OpenAIRE

    Ambjo̸rn, J.; Gizbert-Studnicki, J.(Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. prof. Stanislawa Lojasiewicza 11, Krakow, PL 30-348, Poland); Görlich, A.T.; Jurkiewicz, J.; Loll, R.

    2013-01-01

    The Causal Dynamical Triangulation model of quantum gravity (CDT) is a proposition to evaluate the path integral over space-time geometries using a lattice regularization with a discrete proper time and geometries realized as simplicial manifolds. The model admits a Wick rotation to imaginary time for each space-time configuration. Using computer simulations we determined the phase structure of the model and discovered that it predicts a de Sitter phase with a four-dimensional spherical semi-...

  6. Platonic solids generate their four-dimensional analogues.

    Science.gov (United States)

    Dechant, Pierre Philippe

    2013-11-01

    This paper shows how regular convex 4-polytopes - the analogues of the Platonic solids in four dimensions - can be constructed from three-dimensional considerations concerning the Platonic solids alone. Via the Cartan-Dieudonné theorem, the reflective symmetries of the Platonic solids generate rotations. In a Clifford algebra framework, the space of spinors generating such three-dimensional rotations has a natural four-dimensional Euclidean structure. The spinors arising from the Platonic solids can thus in turn be interpreted as vertices in four-dimensional space, giving a simple construction of the four-dimensional polytopes 16-cell, 24-cell, the F4 root system and the 600-cell. In particular, these polytopes have `mysterious' symmetries, that are almost trivial when seen from the three-dimensional spinorial point of view. In fact, all these induced polytopes are also known to be root systems and thus generate rank-4 Coxeter groups, which can be shown to be a general property of the spinor construction. These considerations thus also apply to other root systems such as A(1)\\oplus I(2)(n) which induces I(2)(n)\\oplus I(2)(n), explaining the existence of the grand antiprism and the snub 24-cell, as well as their symmetries. These results are discussed in the wider mathematical context of Arnold's trinities and the McKay correspondence. These results are thus a novel link between the geometries of three and four dimensions, with interesting potential applications on both sides of the correspondence, to real three-dimensional systems with polyhedral symmetries such as (quasi)crystals and viruses, as well as four-dimensional geometries arising for instance in Grand Unified Theories and string and M-theory. PMID:24132220

  7. Supergravity duals of supersymmetric four dimensional gauge theories

    International Nuclear Information System (INIS)

    This article contains an overview of some recent attempts of understanding supergravity and string duals of four dimensional gauge theories using the AdS/CFT correspondence. We discuss the general philosophy underlying the various ways to realize Super Yang-Mills theories in terms of systems of branes. We then review some of the existing duals for N=2 and N=1 theories. We also discuss differences and similarities with realistic theories. (author)

  8. On the compatibility of Lorentz metrics with linear connections on four-dimensional manifolds

    International Nuclear Information System (INIS)

    This paper considers four-dimensional manifolds upon which there is a Lorentz metric h and a symmetric connection Γ which are originally assumed unrelated. It then derives sufficient conditions on h and Γ (expressed through the curvature tensor of Γ) for Γ to be the Levi-Civita connection of some (local) Lorentz metric g and calculates the relationship between g and h. Some examples are provided which help to assess the strength of the sufficient conditions derived

  9. On the compatibility of Lorentz metrics with linear connections on four-dimensional manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Hall, G S [Department of Mathematical Sciences, University of Aberdeen, Meston Building, Aberdeen, AB24 3UE, Scotland (United Kingdom); Lonie, D P [108e Anderson Drive, Aberdeen, AB15 6BW (United Kingdom)

    2006-03-24

    This paper considers four-dimensional manifolds upon which there is a Lorentz metric h and a symmetric connection {gamma} which are originally assumed unrelated. It then derives sufficient conditions on h and {gamma} (expressed through the curvature tensor of {gamma}) for {gamma} to be the Levi-Civita connection of some (local) Lorentz metric g and calculates the relationship between g and h. Some examples are provided which help to assess the strength of the sufficient conditions derived.

  10. Four-dimensional computed tomographic imaging in the wrist: proof of feasibility in a cadaveric model

    Energy Technology Data Exchange (ETDEWEB)

    Tay, Shian-Chao; Berger, Richard A. [Mayo Clinic College of Medicine, Orthopedics Biomechanics Laboratory, Rochester, MN (United States); Primak, Andrew N.; Amrami, Kimberly K. [Mayo Clinic College of Medicine, Department of Radiology, Rochester, MN (United States); Fletcher, Joel G.; McCollough, Cynthia H. [Mayo Clinic College of Medicine, Department of Radiology, Rochester, MN (United States); Mayo Clinic College of Medicine, CT Innovation Center, Rochester, MN (United States); Schmidt, Bernhard [Siemens Medical Solutions, Forchheim (Germany)

    2007-12-15

    High-resolution real-time three-dimensional (3D) imaging of the moving wrist may provide novel insights into the pathophysiology of joint instability. The purpose of this work was to assess the feasibility of using retrospectively gated spiral computed tomography (CT) to perform four-dimensional (4D) imaging of the moving wrist joint. A cadaver forearm from below the elbow was mounted on a motion simulator which performed radioulnar deviation of the wrist at 30 cycles per minute. An electronic trigger from the simulator provided the ''electrocardiogram'' (ECG) signal required for gated reconstructions. Four-dimensional and 3D images were compared by a blinded observer for image quality and presence of artifacts. Image quality of 4D images was found to be excellent at the extremes of radial and ulnar deviation (end-motion phases). Some artifacts were seen in mid-motion phases. 4D CT musculoskeletal imaging is feasible. Four-dimensional CT may allow clinicians to assess functional (dynamic) instabilities of the wrist joint. (orig.)

  11. Four-dimensional computed tomographic imaging in the wrist: proof of feasibility in a cadaveric model

    International Nuclear Information System (INIS)

    High-resolution real-time three-dimensional (3D) imaging of the moving wrist may provide novel insights into the pathophysiology of joint instability. The purpose of this work was to assess the feasibility of using retrospectively gated spiral computed tomography (CT) to perform four-dimensional (4D) imaging of the moving wrist joint. A cadaver forearm from below the elbow was mounted on a motion simulator which performed radioulnar deviation of the wrist at 30 cycles per minute. An electronic trigger from the simulator provided the ''electrocardiogram'' (ECG) signal required for gated reconstructions. Four-dimensional and 3D images were compared by a blinded observer for image quality and presence of artifacts. Image quality of 4D images was found to be excellent at the extremes of radial and ulnar deviation (end-motion phases). Some artifacts were seen in mid-motion phases. 4D CT musculoskeletal imaging is feasible. Four-dimensional CT may allow clinicians to assess functional (dynamic) instabilities of the wrist joint. (orig.)

  12. New supersymmetric black holes in four dimensional N=2 supergravity

    CERN Document Server

    Mandal, Taniya

    2016-01-01

    In this paper we consider the four dimensional N=2 supergravity theory arising from the compactification of type IIA string theory on a Calabi-Yau manifold. We analyse the supersymmetric flow equations for static, spherically symmetric, single-centered black holes. These flow equations are solved by a set of algebraic equations involving the holomorphic sections and harmonic functions. We examine black hole configurations with D0-D4-D6 charge for which the most general solution of these algebraic equations are considered. Though the black hole solution is unique for a given value of the charges, we find new phases of the black hole solutions upon varying them.

  13. Temporal Parameter Optimization in Four-Dimensional Flash Trajectory Imaging

    International Nuclear Information System (INIS)

    In four-dimensional flash trajectory imaging, temporal parameters include time delay, laser pulse width, gate time, pulse pair repetition frequency and the frame rate of CCD, which directly impact on the acquisition of target trajectories over time. We propose a method of optimizing the temporal parameters of flash trajectory imaging. All the temporal parameters can be estimated by the spatial parameters of the volumes of interest, target scale and velocity, and target sample number. The formulae for optimizing temporal parameters are derived, and the method is demonstrated in an experiment with a ball oscillating as a pendulum. (general)

  14. Four-Dimensional Gallant-Lambert-Vanstone Scalar Multiplication

    CERN Document Server

    Birkner, Peter

    2011-01-01

    The GLV method of Gallant, Lambert and Vanstone (CRYPTO 2001) computes any multiple $kP$ of a point $P$ of prime order $n$ lying on an elliptic curve with a low-degree endomorphism $\\Phi$ (called GLV curve) over $\\mathbb{F}_p$ as \\[kP = k_1P + k_2\\Phi(P), \\quad\\text{with} \\max\\{|k_1|,|k_2|\\}\\leq C\\sqrt n] for some explicit constant $C>0$. Recently, Galbraith, Lin and Scott (EUROCRYPT 2009) extended this method to all curves over $\\mathbb{F}_{p^2}$ which are twists of curves defined over $\\mathbb{F}_p$. These are examples of two-dimensional decompositions (with two new scalars), and the GLS approach shows that for curves with many automorphisms (cubic and quartic twists) one can achieve a four-dimensional decomposition as well. We show in this work how to merge the two approaches in order to get, for twists of any GLV curve over $\\mathbb{F}_{p^2}$, a four-dimensional decomposition together with fast endomorphisms $\\Phi, \\Psi$ over $\\mathbb{F}_{p^2}$ acting on the group generated by a point $P$ of prime order $...

  15. Platonic solids generate their four-dimensional analogues

    CERN Document Server

    Dechant, Pierre-Philippe

    2013-01-01

    In this paper, we show how regular convex 4-polytopes - the analogues of the Platonic solids in four dimensions - can be constructed from three-dimensional considerations concerning the Platonic solids alone. Via the Cartan-Dieudonne theorem, the reflective symmetries of the Platonic solids generate rotations. In a Clifford algebra framework, the space of spinors generating such three-dimensional rotations has a natural four-dimensional Euclidean structure. The spinors arising from the Platonic Solids can thus in turn be interpreted as vertices in four-dimensional space, giving a simple construction of the 4D polytopes 16-cell, 24-cell, the F_4 root system and the 600-cell. In particular, these polytopes have `mysterious' symmetries, that are almost trivial when seen from the three-dimensional spinorial point of view. In fact, all these induced polytopes are also known to be root systems and thus generate rank-4 Coxeter groups, which can be shown to be a general property of the spinor construction. These cons...

  16. Concurrent Boost with Adjuvant Breast Hypofractionated Radiotherapy and Toxicity Assessment

    Directory of Open Access Journals (Sweden)

    Mona M. Sayed

    2015-01-01

    Full Text Available Background: The use of shorter radiotherapy schedules has an economic and logistic advantage for radiotherapy departments, as well as a high degree of patient convenience. The aim of this study is to assess the acute and short-term late toxicities of a hypofractionated radiotherapy schedule with a concomitant boost. Methods: We enrolled 57 eligible patients as group A. These patients received 42.5 Gy in 16 fractions of 2.66 Gy each to the whole breast over 3.2 weeks. A concomitant electron boost of 12 Gy in 16 fractions was also administered which gave an additional 0.75 Gy daily to the lumpectomy area for a total radiation dose of 54.5 Gy. Toxicity was recorded at three weeks and at three months for this group as well as for a control group (group B. The control group comprised 76 eligible patients treated conventionally with 50 Gy to the whole breast over five weeks followed by a sequential electron boost of 12 Gy in 2 Gy per fraction. Results: There were no statistically significant differences observed in the incidence of acute skin toxicity, breast pain, and edema recorded at three weeks or pigmentation and fibrosis recorded at three months between the two groups (P0.05. Conclusion: The results of this study suggest there are no increased acute and shortterm late toxicities affiliated with the hypofractionated schedule plus a concomitant boost as prescribed compared to the conventional fractionation of adjuvant breast radiotherapy. Large randomized trials and long-term follow-up are needed to confirm these favorable findings.

  17. Radiotherapy

    International Nuclear Information System (INIS)

    The book is focussed on the actual knowledge on the clinical radiotherapy and radio-oncology. Besides fundamental and general contributions specific organ systems are treated in detail. The book contains the following contributions: Basic principles, radiobiological fundamentals, physical background, radiation pathology, basics and technique of brachytherapy, methodology and technique of the stereotactic radiosurgery, whole-body irradiation, operative radiotherapy, hadron therapy, hpyerthermia, combined radio-chemo-therapy, biometric clinical studies, intensity modulated radiotherapy, side effects, oncological diagnostics; central nervous system and sense organs, head-neck carcinomas, breast cancer, thorax organs, esophagus carcinoma, stomach carcinoma, pancreas carcinoma, heptabiliary cancer and liver metastases, rectal carcinomas, kidney and urinary tract, prostate carcinoma, testicular carcinoma, female pelvis, lymphatic system carcinomas, soft tissue carcinoma, skin cancer, bone metastases, pediatric tumors, nonmalignant diseases, emergency in radio-oncology, supporting therapy, palliative therapy

  18. The effective action in four-dimensional CDT

    CERN Document Server

    Gizbert-Studnicki, Jakub

    2015-01-01

    We present recent results concerning the measurement and analysis of the effective action in four-dimensional Causal Dynamical Triangulations. The action describes quantum fluctuations of the spatial volume of the CDT universe (or alternatively the scale factor) after integrating out other degrees of freedom. We use the covariance of volume fluctuations to measure and parametrize the effective action inside the de Sitter phase, also called the C phase. We show that the action is consistent with a simple discretization of the minisuperspace action (with a reversed overall sign). We discuss possible subleading corrections and show how to construct a more complicated effective action comprising both integer and half-integer discrete proper time layers. We introduce a new method of the effective action measurement based on the transfer matrix. We show that the results of the new method are fully consistent with the covariance matrix method inside the de Sitter phase. We use the new method to measure the effective...

  19. Radiotherapy

    International Nuclear Information System (INIS)

    The need for radiotherapy research is exemplified by the 100,000 cancer patients who will fail treatment locally and/or regionally annually for the next several years but who would benefit from better local treatment modalities. Theoretically, all of the areas of investigation discussed in this projection paper have the potential to significantly improve local-regional treatment of cancer by radiotherapy alone or in combination with other modalities. In many of the areas of investigation discussed in this paper encouraging results have been obtained in cellular and animal tumor studies and in limited studies in humans as well. In the not too distant future the number of patients who would benefit from better local control may increase by tens of thousands if developments in chemotherapy and/or immunotherapy provide a means to eradicate disseminated microscopic foci of cancer. Thus the efforts to improve local-regional control take on even greater significance

  20. Zonotopes and four-dimensional superconformal field theories

    CERN Document Server

    Kato, A

    2007-01-01

    The a-maximization technique proposed by Intriligator and Wecht allows us to determine the exact R-charges and scaling dimensions of the chiral operators of four-dimensional superconformal field theories. The problem of existence and uniqueness of the solution, however, has not been addressed in general setting. In this paper, it is shown that the a-function has always a unique critical point which is also a global maximum for a large class of quiver gauge theories specified by toric diagrams. Our proof is based on the observation that the a-function is given by the volume of a three dimensional polytope called "zonotope", and the uniqueness essentially follows from Brunn-Minkowski inequality for the volume of convex bodies. We also show a universal upper bound for the exact R-charges, and the monotonicity of a-function in the sense that a-function decreases whenever the toric diagram shrinks. The relationship between a-maximization and volume-minimization is also discussed.

  1. An explicit four-dimensional variational data assimilation method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new data assimilation method called the explicit four-dimensional variational (4DVAR) method is proposed. In this method, the singular value decomposition (SVD) is used to construct the orthogonal basis vectors from a forecast ensemble in a 4D space. The basis vectors represent not only the spatial structure of the analysis variables but also the temporal evolution. After the analysis variables are ex-pressed by a truncated expansion of the basis vectors in the 4D space, the control variables in the cost function appear explicitly, so that the adjoint model, which is used to derive the gradient of cost func-tion with respect to the control variables, is no longer needed. The new technique significantly simpli-fies the data assimilation process. The advantage of the proposed method is demonstrated by several experiments using a shallow water numerical model and the results are compared with those of the conventional 4DVAR. It is shown that when the observation points are very dense, the conventional 4DVAR is better than the proposed method. However, when the observation points are sparse, the proposed method performs better. The sensitivity of the proposed method with respect to errors in the observations and the numerical model is lower than that of the conventional method.

  2. An economical approach to four-dimensional variational data assimilation

    Science.gov (United States)

    Wang, Bin; Liu, Juanjuan; Wang, Shudong; Cheng, Wei; Juan, Liu; Liu, Chengsi; Xiao, Qingnong; Kuo, Ying-Hwa

    2010-07-01

    Four-dimensional variational data assimilation (4DVar) is one of the most promising methods to provide optimal analysis for numerical weather prediction (NWP). Five national NWP centers in the world have successfully applied 4DVar methods in their global NWPs, thanks to the increment method and adjoint technique. However, the application of 4DVar is still limited by the computer resources available at many NWP centers and research institutes. It is essential, therefore, to further reduce the computational cost of 4DVar. Here, an economical approach to implement 4DVar is proposed, using the technique of dimensionreduced projection (DRP), which is called "DRP-4DVar." The proposed approach is based on dimension reduction using an ensemble of historical samples to define a subspace. It directly obtains an optimal solution in the reduced space by fitting observations with historical time series generated by the model to form consistent forecast states, and therefore does not require implementation of the adjoint of tangent linear approximation. To evaluate the performance of the DRP-4DVar on assimilating different types of mesoscale observations, some observing system simulation experiments are conducted using MM5 and a comparison is made between adjoint-based 4DVar and DRP-4DVar using a 6-hour assimilation window.

  3. Four-dimensional unsubtraction from the loop-tree duality

    CERN Document Server

    Sborlini, German F R; Hernandez-Pinto, Roger; Rodrigo, German

    2016-01-01

    We present a new algorithm to construct a purely four dimensional representation of higher-order perturbative corrections to physical cross-sections at next-to-leading order (NLO). The algorithm is based on the loop-tree duality (LTD), and it is implemented by introducing a suitable mapping between the external and loop momenta of the virtual scattering amplitudes with the external momenta of the real emission corrections. In this way, the sum over degenerate infrared states is performed at the integrand level and the cancellation of infrared divergences occurs locally without introducing subtraction counter-terms to deal with soft and final-state collinear singularities. The dual representation of ultraviolet counter-terms is also discussed in detail, in particular for self-energy contributions. The method is first illustrated with the scalar three-point function, before proceeding with the calculation of the physical cross-section for $\\gamma^* \\to q \\bar{q}(g)$, at its generalisation to multi-leg processes...

  4. An explicit four-dimensional variational data assimilation method

    Institute of Scientific and Technical Information of China (English)

    QIU ChongJian; ZHANG Lei; SHAO AiMei

    2007-01-01

    A new data assimilation method called the explicit four-dimensional variational (4DVAR) method is proposed. In this method, the singular value decomposition (SVD) is used to construct the orthogonal basis vectors from a forecast ensemble in a 4D space. The basis vectors represent not only the spatial structure of the analysis variables but also the temporal evolution. After the analysis variables are expressed by a truncated expansion of the basis vectors in the 4D space, the control variables in the cost function appear explicitly, so that the adjoint model, which is used to derive the gradient of cost function with respect to the control variables, is no longer needed. The new technique significantly simplifies the data assimilation process. The advantage of the proposed method is demonstrated by several experiments using a shallow water numerical model and the results are compared with those of the conventional 4DVAR. It is shown that when the observation points are very dense, the conventional 4DVAR is better than the proposed method. However, when the observation points are sparse, the proposed method performs better. The sensitivity of the proposed method with respect to errors in the observations and the numerical model is lower than that of the conventional method.

  5. Decision-making for supplying energy projects: A four-dimensional model

    International Nuclear Information System (INIS)

    Highlights: • Extant pipeline evaluation models offer insufficient supplier analysis tools. • We offer a four-dimensional decision-making tool to augment extant models. • Model employs four filters to help decision makers eliminate unsuitable suppliers. • Aids in prioritization of best courses of action for overcoming obstacles. • Case study of Nabucco pipeline shows Azerbaijan would have been best supply option. - Abstract: Importing states and regions employ myriad strategies to enhance energy security, from stockpiling to diversification to efficiency programs. As has occurred in recent years, importers can seek diversification by initiating pipeline and liquefied natural gas projects, meaning they may also have to select suppliers. However, most extant pipeline evaluation models erroneously assume suppliers are known and thus neglect supplier selection. We propose a decision-making tool to augment these older models: a systematic and replicable four-dimensional model to help policymakers and managers identify suitable suppliers and prioritize the best courses of action for overcoming obstacles. The first three dimensions—timeframe, supply availability and infrastructure constraints—filter out unsuitable suppliers. The fourth dimension then assesses the political, geopolitical and commercial stability of the remaining candidates. To demonstrate the model in practice, we assess the original Nabucco pipeline proposal, which was designed to transport gas from the Caspian and Middle East regions to Europe

  6. A method for the reconstruction of four-dimensional synchronized CT scans acquired during free breathing

    International Nuclear Information System (INIS)

    Breathing motion is a significant source of error in radiotherapy treatment planning for the thorax and upper abdomen. Accounting for breathing motion has a profound effect on the size of conformal radiation portals employed in these sites. Breathing motion also causes artifacts and distortions in treatment planning computed tomography (CT) scans acquired during free breathing and also causes a breakdown of the assumption of the superposition of radiation portals in intensity-modulated radiation therapy, possibly leading to significant dose delivery errors. Proposed voluntary and involuntary breath-hold techniques have the potential for reducing or eliminating the effects of breathing motion, however, they are limited in practice, by the fact that many lung cancer patients cannot tolerate holding their breath. We present an alternative solution to accounting for breathing motion in radiotherapy treatment planning, where multislice CT scans are collected simultaneously with digital spirometry over many free breathing cycles to create a four-dimensional (4-D) image set, where tidal lung volume is the additional dimension. An analysis of this 4-D data leads to methods for digital-spirometry, based elimination or accounting of breathing motion artifacts in radiotherapy treatment planning for free breathing patients. The 4-D image set is generated by sorting free-breathing multislice CT scans according to user-defined tidal-volume bins. A multislice CT scanner is operated in the cine mode, acquiring 15 scans per couch position, while the patient undergoes simultaneous digital-spirometry measurements. The spirometry is used to retrospectively sort the CT scans by their correlated tidal lung volume within the patient's normal breathing cycle. This method has been prototyped using data from three lung cancer patients. The actual tidal lung volumes agreed with the specified bin volumes within standard deviations ranging between 22 and 33 cm3. An analysis of sagittal and

  7. Four-dimensional IMRT treatment planning using a DMLC motion-tracking algorithm

    Science.gov (United States)

    Suh, Yelin; Sawant, Amit; Venkat, Raghu; Keall, Paul J.

    2009-06-01

    The purpose of this study is to develop a four-dimensional (4D) intensity-modulated radiation therapy (IMRT) treatment-planning method by modifying and applying a dynamic multileaf collimator (DMLC) motion-tracking algorithm. The 4D radiotherapy treatment scenario investigated is to obtain a 4D treatment plan based on a 4D computed tomography (CT) planning scan and to have the delivery flexible enough to account for changes in tumor position during treatment delivery. For each of 4D CT planning scans from 12 lung cancer patients, a reference phase plan was created; with its MLC leaf positions and three-dimensional (3D) tumor motion, the DMLC motion-tracking algorithm generated MLC leaf sequences for the plans of other respiratory phases. Then, a deformable dose-summed 4D plan was created by merging the leaf sequences of individual phase plans. Individual phase plans, as well as the deformable dose-summed 4D plan, are similar for each patient, indicating that this method is dosimetrically robust to the variations of fractional time spent in respiratory phases on a given 4D CT planning scan. The 4D IMRT treatment-planning method utilizing the DMLC motion-tracking algorithm explicitly accounts for 3D tumor motion and thus hysteresis and nonlinear motion, and is deliverable on a linear accelerator.

  8. Benchmarking Dosimetric Quality Assessment of Prostate Intensity-Modulated Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Senthi, Sashendra, E-mail: sasha.senthi@petermac.org [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Gill, Suki S. [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Haworth, Annette; Kron, Tomas; Cramb, Jim [Department of Physical Sciences, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Rolfo, Aldo [Radiation Therapy Services, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Thomas, Jessica [Biostatistics and Clinical Trials, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Duchesne, Gillian M. [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Hamilton, Christopher H.; Joon, Daryl Lim [Radiation Oncology Department, Austin Repatriation Hospital, Heidelberg, VIC (Australia); Bowden, Patrick [Radiation Oncology Department, Tattersall' s Cancer Center, East Melbourne, VIC (Australia); Foroudi, Farshad [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia)

    2012-02-01

    Purpose: To benchmark the dosimetric quality assessment of prostate intensity-modulated radiotherapy and determine whether the quality is influenced by disease or treatment factors. Patients and Methods: We retrospectively analyzed the data from 155 consecutive men treated radically for prostate cancer using intensity-modulated radiotherapy to 78 Gy between January 2007 and March 2009 across six radiotherapy treatment centers. The plan quality was determined by the measures of coverage, homogeneity, and conformity. Tumor coverage was measured using the planning target volume (PTV) receiving 95% and 100% of the prescribed dose (V{sub 95%} and V{sub 100%}, respectively) and the clinical target volume (CTV) receiving 95% and 100% of the prescribed dose. Homogeneity was measured using the sigma index of the PTV and CTV. Conformity was measured using the lesion coverage factor, healthy tissue conformity index, and the conformity number. Multivariate regression models were created to determine the relationship between these and T stage, risk status, androgen deprivation therapy use, treatment center, planning system, and treatment date. Results: The largest discriminatory measurements of coverage, homogeneity, and conformity were the PTV V{sub 95%}, PTV sigma index, and conformity number. The mean PTV V{sub 95%} was 92.5% (95% confidence interval, 91.3-93.7%). The mean PTV sigma index was 2.10 Gy (95% confidence interval, 1.90-2.20). The mean conformity number was 0.78 (95% confidence interval, 0.76-0.79). The treatment center independently influenced the coverage, homogeneity, and conformity (all p < .0001). The planning system independently influenced homogeneity (p = .038) and conformity (p = .021). The treatment date independently influenced the PTV V{sub 95%} only, with it being better at the start (p = .013). Risk status, T stage, and the use of androgen deprivation therapy did not influence any aspect of plan quality. Conclusion: Our study has benchmarked measures

  9. Benchmarking Dosimetric Quality Assessment of Prostate Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To benchmark the dosimetric quality assessment of prostate intensity-modulated radiotherapy and determine whether the quality is influenced by disease or treatment factors. Patients and Methods: We retrospectively analyzed the data from 155 consecutive men treated radically for prostate cancer using intensity-modulated radiotherapy to 78 Gy between January 2007 and March 2009 across six radiotherapy treatment centers. The plan quality was determined by the measures of coverage, homogeneity, and conformity. Tumor coverage was measured using the planning target volume (PTV) receiving 95% and 100% of the prescribed dose (V95% and V100%, respectively) and the clinical target volume (CTV) receiving 95% and 100% of the prescribed dose. Homogeneity was measured using the sigma index of the PTV and CTV. Conformity was measured using the lesion coverage factor, healthy tissue conformity index, and the conformity number. Multivariate regression models were created to determine the relationship between these and T stage, risk status, androgen deprivation therapy use, treatment center, planning system, and treatment date. Results: The largest discriminatory measurements of coverage, homogeneity, and conformity were the PTV V95%, PTV sigma index, and conformity number. The mean PTV V95% was 92.5% (95% confidence interval, 91.3–93.7%). The mean PTV sigma index was 2.10 Gy (95% confidence interval, 1.90–2.20). The mean conformity number was 0.78 (95% confidence interval, 0.76–0.79). The treatment center independently influenced the coverage, homogeneity, and conformity (all p 95% only, with it being better at the start (p = .013). Risk status, T stage, and the use of androgen deprivation therapy did not influence any aspect of plan quality. Conclusion: Our study has benchmarked measures of coverage, homogeneity, and conformity for the treatment of prostate cancer using IMRT. The differences seen between centers and planning systems and the coverage deterioration

  10. Implementation of a risk assessment tool based on a probabilistic safety assessment developed for radiotherapy practices

    International Nuclear Information System (INIS)

    The present work describes the implementation process and main results of the risk assessment to the radiotherapy practices with Linear Accelerators (Linac), with cobalt 60, and with brachytherapy. These evaluations were made throughout the risk assessment tool for radiotherapy practices SEVRRA (risk evaluation system for radiotherapy), developed at the Mexican National Commission in Nuclear Safety and Safeguards derived from the outcome obtained with the Probabilistic Safety Analysis developed at the Ibero-American Regulators Forum for these radiotherapy facilities. The methodology used is supported by risk matrices method, a mathematical tool that estimates the risk to the patient, radiation workers and public from mechanical failures, mis calibration of the devices, human mistakes, and so. The initiating events are defined as those undesirable events that, together with other failures, can produce a delivery of an over-dose or an under-dose of the medical prescribed dose, to the planned target volume, or a significant dose to non prescribed human organs. Initiating events frequency and reducer of its frequency (actions intended to avoid the accident) are estimated as well as robustness of barriers to those actions, such as mechanical switches, which detect and prevent the accident from occurring. The spectrum of the consequences is parameterized, and the actions performed to reduce the consequences are identified. Based on this analysis, a software tool was developed in order to simplify the evaluations to radiotherapy installations and it has been applied as a first step forward to some Mexican installations, as part of a national implementation process, the final goal is evaluation of all Mexican facilities in the near future. The main target and benefits of the SEVRRA implementation are presented in this paper. (Author)

  11. Patient-specific modelling of whole heart anatomy, dynamics and haemodynamics from four-dimensional cardiac CT images

    OpenAIRE

    Mihalef, Viorel; Ionasec, Razvan Ioan; Sharma, Puneet; Georgescu, Bogdan; Voigt, Ingmar; Suehling, Michael; Comaniciu, Dorin

    2011-01-01

    There is a growing need for patient-specific and holistic modelling of the heart to support comprehensive disease assessment and intervention planning as well as prediction of therapeutic outcomes. We propose a patient-specific model of the whole human heart, which integrates morphology, dynamics and haemodynamic parameters at the organ level. The modelled cardiac structures are robustly estimated from four-dimensional cardiac computed tomography (CT), including all four chambers and valves a...

  12. Four-dimensional coronary morphology and computational hemodynamics

    Science.gov (United States)

    Wahle, Andreas; Mitchell, Steven C.; Ramaswamy, Sharan D.; Chandran, Krishnan B.; Sonka, Milan

    2001-07-01

    Conventional reconstructions from intravascular ultrasound (IVUS) stack the frames as acquired during the pullback of the catheter to form a straight three-dimensional volume, thus neglecting the vessel curvature and merging images from different heart phases. We are developing a comprehensive system for fusion of the IVUS data with the pullback path as determined from x-ray angiography, to create a geometrically accurate 4-D (3-D plus time) model of the coronary vasculature as basis for computational hemodynamics. The overall goal of our work is to correlate shear stress with plaque thickness. The IVUS data are obtained in a single pullback using an automated pullback device; the frames are afterwards assigned to their respective heart phases based upon the ECG signal. A set of 3-D models is reconstructed by fusion of IVUS and angiographic data corresponding to the same ECG-gated heart phase; methods of computational fluid dynamics (CFD) are applied to obtain important hemodynamic data. Combining these models yields the final 4-D reconstruction. Visualization is performed using the platform-independent VRML standard for a user-friendly manipulation of the scene. An extension for virtual angioscopy allows an easy assessment of the vessel features within their local context. Validation was successfully performed both in-vitro and in-vivo.

  13. Improving the Horizontal Transport in the Lower Troposphere with Four Dimensional Data Assimilation

    Science.gov (United States)

    The physical processes involved in air quality modeling are governed by dynamically-generated meteorological model fields. This research focuses on reducing the uncertainty in the horizontal transport in the lower troposphere by improving the four dimensional data assimilation (F...

  14. Slow gantry rotation acquisition technique for on-board four-dimensional digital tomosynthesis

    International Nuclear Information System (INIS)

    Purpose: Four-dimensional cone-beam computed tomography (4D CBCT) has been investigated for motion imaging in the radiotherapy treatment room. The drawbacks of 4D CBCT are long scan times and high imaging doses. The aims of this study were to develop and investigate a slow gantry rotation acquisition protocol for four-dimensional digital tomosynthesis (4D DTS) as a faster, lower dose alternative to 4D CBCT. Methods: This technique was implemented using an On-Board Imager kV imaging system (Varian Medical Systems, Palo Alto, CA) mounted on the gantry of a linear accelerator. The general procedure for 4D DTS imaging using slow gantry rotation acquisition consists of the following steps: (1) acquire projections over a limited gantry rotation angle in a single motion with constant frame rate and gantry rotation speed; (2) generate a respiratory signal and temporally match projection images with appropriate points from the respiratory signal; (3) use the respiratory signal to assign phases to each of the projection images; (4) sort projection images into phase bins; and (5) reconstruct phase images. Phantom studies were conducted to validate theoretically derived relationships between acquisition and respiratory parameters. Optimization of acquisition parameters was then conducted by simulating lung scans using patient data. Lung tumors with approximate volumes ranging from 0.12 to 1.53 cm3 were studied. Results: A protocol for slow gantry rotation 4D DTS was presented. Equations were derived to express relationships between acquisition parameters (frame rate, phase window, and angular intervals between projections), respiratory cycle durations, and resulting acquisition times and numbers of projections. The phantom studies validated the relationships, and the patient studies resulted in determinations of appropriate acquisition parameters. The phase window must be set according to clinical goals. For 10% phase windows, we found that appropriate frame rates ranging from

  15. Classification of the four-dimensional power-commutative real division algebras

    OpenAIRE

    Darpö, Erik; Rochdi, Abdellatif

    2009-01-01

    A classification of all four-dimensional power-commutative real division algebras is given. It is shown that every four-dimensional power-commutative real division algebra is an isotope of a particular kind of a quadratic division algebra. The description of such isotopes in dimension four and eight is reduced to the description of quadratic division algebras. In dimension four this leads to a complete and irredundant classification. As a special case, the finite-dimensional power-commutative...

  16. A new four-dimensional hyperchaotic Lorenz system and its adaptive control

    International Nuclear Information System (INIS)

    Based on the Lorenz chaotic system, this paper constructs a new four-dimensional hyperchaotic Lorenz system, and studies the basic dynamic behaviours of the system. The Routh—Hurwitz theorem is applied to derive the stability conditions of the proposed system. Furthermore, based on Lyapunov stability theory, an adaptive controller is designed and the new four-dimensional hyperchaotic Lorenz system is controlled at equilibrium point. Numerical simulation results are presented to illustrate the effectiveness of this method. (general)

  17. Primary tracheobronchial amyloidosis associated with tracheobronchomegaly evaluated by novel four-dimensional functional CT.

    Science.gov (United States)

    Uddin, A K M Nizam; Mansfield, Darren R; Farmer, Michael W; Lau, Kenneth K

    2015-12-01

    Amyloid is a heterogeneous family of extracellular proteinaceous deposits characterized by apple-green birefringence on polarized light microscopy. There are rare case reports of these extracellular deposits accumulating in the upper and central airways. Progressive infiltration may impair glottic and airway function with some cases requiring intervention to improve flow. Bronchoscopy and lung function testing provide dynamic information to monitor for disease progression; however, the recent development of 320 multislice computed tomography (320 CT) enables dynamic, four-dimensional (4-D) evaluation of laryngeal and tracheal structure and function and presents as a noninvasive, low-radiation dose surveillance tool. We reviewed a 43-year-old man with primary amyloidosis of the larynx and central airways who presented with an 18-year history of progressive dysphonia without breathlessness and preserved lung function. 4-D CT demonstrated marked thickening of supraglottic folds and trachea with marked tracheal dilatation. Despite gross structural abnormalities, dynamic function assessed throughout inspiration and expiration was normal, demonstrating neither rigidity nor dynamic collapse. This combination of structural and functional assessment of the proximal airway by 4-D CT is a novel application to surveillance for laryngeal and tracheal amyloid. PMID:26740884

  18. A technique for quantifying wrist motion using four-dimensional computed tomography: approach and validation.

    Science.gov (United States)

    Zhao, Kristin; Breighner, Ryan; Holmes, David; Leng, Shuai; McCollough, Cynthia; An, Kai-Nan

    2015-07-01

    Accurate quantification of subtle wrist motion changes resulting from ligament injuries is crucial for diagnosis and prescription of the most effective interventions for preventing progression to osteoarthritis. Current imaging techniques are unable to detect injuries reliably and are static in nature, thereby capturing bone position information rather than motion which is indicative of ligament injury. A recently developed technique, 4D (three dimensions + time) computed tomography (CT) enables three-dimensional volume sequences to be obtained during wrist motion. The next step in successful clinical implementation of the tool is quantification and validation of imaging biomarkers obtained from the four-dimensional computed tomography (4DCT) image sequences. Measures of bone motion and joint proximities are obtained by: segmenting bone volumes in each frame of the dynamic sequence, registering their positions relative to a known static posture, and generating surface polygonal meshes from which minimum distance (proximity) measures can be quantified. Method accuracy was assessed during in vitro simulated wrist movement by comparing a fiducial bead-based determination of bone orientation to a bone-based approach. The reported errors for the 4DCT technique were: 0.00-0.68 deg in rotation; 0.02-0.30 mm in translation. Results are on the order of the reported accuracy of other image-based kinematic techniques. PMID:25901447

  19. Objective assessment of dermatitis following post-operative radiotherapy in patients with breast cancer treated with breast-conserving treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Ken; Takenaka, Tadashi; Tanaka, Eiichi; Kuriyama, Keiko; Yoshida, Mineo [National Hospital Organization Osaka National Hospital (Japan). Dept. of Radiology; Yamazaki, Hideya; Nishimura, Tsunehiko [Kyoto Prefectural Univ. of Medicine (Japan). Dept. of Radiology; Kotsuma, Tadayuki [Osaka Univ. Graduate School of Medicine (Japan). Dept. of Radiation Oncology; Fujita, Yuka [Osaka Univ. Graduate School of Medicine (Japan). Dept. of Diagnostic and Interventional Radiology; Masuda, Norikazu [National Hospital Organization Osaka National Hospital (Japan). Dept. of Surgery

    2010-11-15

    To evaluate radiation dermatitis objectively in patients with breast cancer who had undergone post-operative radiotherapy after breast-conserving surgery. Skin color (L{sup *}, a{sup *}, and b{sup *} values) and moisture analyses were performed for both breasts (before, after, 1 month, 6 months, and 1 year after radiotherapy) to examine irradiated and non-irradiated skin divided into four quadrants in 118 patients. These patients underwent breast conservative surgery followed by 50 Gy/25 fractions (median) of radiotherapy with or without boost irradiation (10 Gy/5 fractions). L{sup *}, a{sup *}, and moisture values were changed by irradiation and maximized at completion or 1 month after radiotherapy. One year after radiotherapy, the skin color had returned to the range observed prior to radiotherapy. However, moisture did not return to previous values even 1 year after treatment. The lateral upper side (quadrant C) showed greater changes than other quadrants in the L{sup *} value (darker) at the end of radiotherapy. The Common Toxicity Criteria version 3 scores were found to correlate well with a{sup *} and L{sup *} values at the completion and 1 month after radiotherapy. Boost radiotherapy intensified reddish and darker color changes at the completion of radiotherapy, while chemotherapy did not intensify the skin reaction caused by radiotherapy. Moisture impairment as a result of irradiation lasts longer than color alterations. Objective assessments are useful for analyzing radiation dermatitis. (orig.)

  20. Model-based risk assessment for motion effects in 3D radiotherapy of lung tumors

    Science.gov (United States)

    Werner, René; Ehrhardt, Jan; Schmidt-Richberg, Alexander; Handels, Heinz

    2012-02-01

    Although 4D CT imaging becomes available in an increasing number of radiotherapy facilities, 3D imaging and planning is still standard in current clinical practice. In particular for lung tumors, respiratory motion is a known source of uncertainty and should be accounted for during radiotherapy planning - which is difficult by using only a 3D planning CT. In this contribution, we propose applying a statistical lung motion model to predict patients' motion patterns and to estimate dosimetric motion effects in lung tumor radiotherapy if only 3D images are available. Being generated based on 4D CT images of patients with unimpaired lung motion, the model tends to overestimate lung tumor motion. It therefore promises conservative risk assessment regarding tumor dose coverage. This is exemplarily evaluated using treatment plans of lung tumor patients with different tumor motion patterns and for two treatment modalities (conventional 3D conformal radiotherapy and step-&- shoot intensity modulated radiotherapy). For the test cases, 4D CT images are available. Thus, also a standard registration-based 4D dose calculation is performed, which serves as reference to judge plausibility of the modelbased 4D dose calculation. It will be shown that, if combined with an additional simple patient-specific breathing surrogate measurement (here: spirometry), the model-based dose calculation provides reasonable risk assessment of respiratory motion effects.

  1. Chaotic behaviour of nonlinear coupled reaction–diffusion system in four-dimensional space

    Indian Academy of Sciences (India)

    Li Zhang; Shutang Liu; Chenglong Yu

    2014-06-01

    In recent years, nonlinear coupled reaction–diffusion (CRD) system has been widely investigated by coupled map lattice method. Previously, nonlinear behaviour was observed dynamically when one or two of the three variables in the discrete system change. In this paper, we consider the chaotic behaviour when three variables change, which is called as four-dimensional chaos. When two parameters in the discrete system are unknown, we first give the existing condition of the chaos in four-dimensional space by the generalized definitions of spatial periodic orbits and spatial chaos. In addition, the chaotic behaviour will vary with the parameters. Then we propose a generalized Lyapunov exponent in four-dimensional space to characterize the different effects of parameters on the chaotic behaviour, which has not been studied in detail. In order to verify the chaotic behaviour of the system and the different effects clearly, we simulate the dynamical behaviour in two- and three-dimensional spaces.

  2. Dynamical simulation of neutron-induced fission of uranium isotopes using four-dimensional Langevin equations

    Science.gov (United States)

    Pahlavani, M. R.; Mirfathi, S. M.

    2016-04-01

    Four-dimensional Langevin equations have been suggested for the dynamical simulation of neutron-induced fission at low and medium excitation energies. The mass distribution of the fission fragments, the neutron multiplicity, and the fission cross section for the thermal and fast neutron-induced fission of 233U, 235U, and 238U is studied by considering energy dissipation of the compound nucleus through the fission using four-dimensional Langevin equations combined with a Monte Carlo simulation approach. The calculated results using this approach indicate reasonable agreement with available experimental data.

  3. Carcinomas of endometrium and cervix: magnetic resonance assessment of changes following radiotherapy

    International Nuclear Information System (INIS)

    To present the changes induced at the tissue level in patients subjected to external radiotherapy and brachytherapy to treat carcinomas of endometrium and cervix, as disclosed by magnetic resonance (MR). The MR study dealt with 26 patients 14 with endometrial carcinoma and 12 with cervical carcinoma who were treated with external radiotherapy and brachytherapy. The features assessed retrospectively were bone marrow of the lumbar and sacral spine, pelvic fat, abdominal wall, uterine, junction and size, rectal and bladder wall and pelvic musculature. The most common changes observed after radiotherapy according to our study were changes in signal intensity in the bone marrow of the pelvic bones (88%), followed by changes in the pelvic fat (65.3%). Other radiotherapy-related findings in order of frequency were cervical fibrosis, colitis and cystitis. Radiotherapy induces changes in the tissue of the pelvic structures, and the knowledge of these changes is important in the evaluation of the follow-up studies of these patients. (Author) 12 refs

  4. Objective assessment of cosmetic outcome after targeted intraoperative radiotherapy in breast cancer

    DEFF Research Database (Denmark)

    Keshtgar, Mohammed R S; Williams, Norman R; Bulsara, Max;

    2013-01-01

    fibrosis and thus impair cosmesis further, so we objectively evaluated the aesthetic outcome of patients within the TARGIT randomised controlled trial. We have used an objective assessment tool for evaluation of cosmetic outcome. Frontal digital photographs were taken at baseline (before TARGIT or EBRT...... objective assessment in a randomised setting, the aesthetic outcome of patients demonstrates that those treated with TARGIT have a superior cosmetic result to those patients who received conventional external beam radiotherapy....

  5. Effect of four-dimensional variational data assimilation in case of nonlinear instability

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of four-dimensional variational data assimilation on the reduction of the forecast errors is investigated for both stable and unstable flows. Numerical results show that the effect is generally positive. Particularly,its effect is much more significant in the presence of nonlinear instability

  6. The Existence of Silnikov's Orbit in Four-dimensional Duffing's Systems

    Institute of Scientific and Technical Information of China (English)

    Wei Li; Peng-cheng Xu

    2003-01-01

    The existence of Silnikov's orbits in a four-dimensional dynamical system is discussed. The existence of Silnikov's orbit resulting in chaotic dynamics is established by the fiber structure of invariant manifold and high-dimensional Melnikov method. Numerical simulations are given to demonstrate the theoretical analysis.

  7. Registration-based Reconstruction of Four-dimensional Cone Beam Computed Tomography

    DEFF Research Database (Denmark)

    Christoffersen, Christian; Hansen, David Christoffer; Poulsen, Per Rugaard; Sørensen, Thomas Sangild

    2013-01-01

    We present a new method for reconstruction of four-dimensional (4D) cone beam computed tomography from an undersampled set of X-ray projections. The novelty of the proposed method lies in utilizing optical flow based registration to facilitate that each temporal phase is reconstructed from the full...

  8. Four-dimensional Osserman-Ivanov-Petrova metrics of neutral signature

    Energy Technology Data Exchange (ETDEWEB)

    Calvino-Louzao, Esteban; GarcIa-RIo, Eduardo; Vazquez-Lorenzo, Ramon [Department of Geometry and Topology, Faculty of Mathematics, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain)

    2007-05-07

    Algebraic curvature tensors which are Osserman-IP in the (- - + +)-signature setting are completely determined. As a consequence, it is shown that a four-dimensional pointwise Osserman-IP manifold is a space of constant sectional curvature or, otherwise, at each point the Jacobi operators either vanish or they are two-step nilpotent.

  9. Five-dimensional moving brane solutions with four-dimensional limiting behavior

    International Nuclear Information System (INIS)

    Under certain conditions some solutions to five-dimensional heterotic M theory can be accurately described by the four-dimensional action of the theory. We consider the connection between solutions of four- and five-dimensional heterotic M theory when moving five-branes are present in the bulk. We begin by describing how to raise the known four-dimensional moving brane solutions to obtain approximate solutions to the five-dimensional theory, presenting for the first time the metric template necessary for this procedure. We then present the first solutions to the five-dimensional theory containing moving five-branes. We then discuss the correspondence between solutions of the five- and four-dimensional actions as presented. Specifically, we show that our exact, five-dimensional solution only corresponds to one of the previously known four-dimensional solutions when the embedded five-brane is static. In other words, higher Kaluza-Klein modes are essential in the description of the five-brane's motion in our new solution

  10. Four dimensional magnetic resonance imaging with retrospective k-space reordering: A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yilin; Yin, Fang-Fang; Cai, Jing, E-mail: jing.cai@duke.edu [Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Chen, Nan-kuei [Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Brain Imaging and Analysis Center, Duke University Medical Center, Box 2737, Hock Plaza, Durham, North Carolina 27710 (United States); Chu, Mei-Lan [Brain Imaging and Analysis Center, Duke University Medical Center, Box 2737, Hock Plaza, Durham, North Carolina 27710 (United States)

    2015-02-15

    Purpose: Current four dimensional magnetic resonance imaging (4D-MRI) techniques lack sufficient temporal/spatial resolution and consistent tumor contrast. To overcome these limitations, this study presents the development and initial evaluation of a new strategy for 4D-MRI which is based on retrospective k-space reordering. Methods: We simulated a k-space reordered 4D-MRI on a 4D digital extended cardiac-torso (XCAT) human phantom. A 2D echo planar imaging MRI sequence [frame rate (F) = 0.448 Hz; image resolution (R) = 256 × 256; number of k-space segments (N{sub KS}) = 4] with sequential image acquisition mode was assumed for the simulation. Image quality of the simulated “4D-MRI” acquired from the XCAT phantom was qualitatively evaluated, and tumor motion trajectories were compared to input signals. In particular, mean absolute amplitude differences (D) and cross correlation coefficients (CC) were calculated. Furthermore, to evaluate the data sufficient condition for the new 4D-MRI technique, a comprehensive simulation study was performed using 30 cancer patients’ respiratory profiles to study the relationships between data completeness (C{sub p}) and a number of impacting factors: the number of repeated scans (N{sub R}), number of slices (N{sub S}), number of respiratory phase bins (N{sub P}), N{sub KS}, F, R, and initial respiratory phase at image acquisition (P{sub 0}). As a proof-of-concept, we implemented the proposed k-space reordering 4D-MRI technique on a T2-weighted fast spin echo MR sequence and tested it on a healthy volunteer. Results: The simulated 4D-MRI acquired from the XCAT phantom matched closely to the original XCAT images. Tumor motion trajectories measured from the simulated 4D-MRI matched well with input signals (D = 0.83 and 0.83 mm, and CC = 0.998 and 0.992 in superior–inferior and anterior–posterior directions, respectively). The relationship between C{sub p} and N{sub R} was found best represented by an exponential function

  11. Four-dimensional optical coherence tomography imaging of total liquid ventilated rats

    Science.gov (United States)

    Kirsten, Lars; Schnabel, Christian; Gaertner, Maria; Koch, Edmund

    2013-06-01

    Optical coherence tomography (OCT) can be utilized for the spatially and temporally resolved visualization of alveolar tissue and its dynamics in rodent models, which allows the investigation of lung dynamics on the microscopic scale of single alveoli. The findings could provide experimental input data for numerical simulations of lung tissue mechanics and could support the development of protective ventilation strategies. Real four-dimensional OCT imaging permits the acquisition of several OCT stacks within one single ventilation cycle. Thus, the entire four-dimensional information is directly obtained. Compared to conventional virtual four-dimensional OCT imaging, where the image acquisition is extended over many ventilation cycles and is triggered on pressure levels, real four-dimensional OCT is less vulnerable against motion artifacts and non-reproducible movement of the lung tissue over subsequent ventilation cycles, which widely reduces image artifacts. However, OCT imaging of alveolar tissue is affected by refraction and total internal reflection at air-tissue interfaces. Thus, only the first alveolar layer beneath the pleura is visible. To circumvent this effect, total liquid ventilation can be carried out to match the refractive indices of lung tissue and the breathing medium, which improves the visibility of the alveolar structure, the image quality and the penetration depth and provides the real structure of the alveolar tissue. In this study, a combination of four-dimensional OCT imaging with total liquid ventilation allowed the visualization of the alveolar structure in rat lung tissue benefiting from the improved depth range beneath the pleura and from the high spatial and temporal resolution.

  12. Radiation safety assessment of cobalt 60 external beam radiotherapy using the risk-matrix method

    International Nuclear Information System (INIS)

    External beam radiotherapy is the only practice in which humans are placed directly in a radiation beam with the intention to deliver a very high dose. This is why safety in radiotherapy is very critical, and is a matter of interest to both radiotherapy departments and regulatory bodies. Accidental exposures have occurred throughout the world, thus showing the need for systematic safety assessments, capable to identify preventive measures and to minimize consequences of accidental exposure. Risk-matrix is a systematic approach which combines the relevant event features to assess the overall risk of each particular event. Once an event sequence is identified, questions such as how frequent the event, how severe the potential consequences and how reliable the existing safety measures are answered in a risk-matrix table. The ultimate goal is to achieve that the overall risk for events with severe consequences should always be low o very low. In the present study, the risk-matrix method has been applied to an hypothetical radiotherapy department, which could be equivalent to an upper level hospital of the Ibero American region, in terms of safety checks and preventive measures. The application of the method has identified 76 event sequences and revealed that the hypothetical radiotherapy department is sufficiently protected (low risk) against them, including 23 event sequences with severe consequences. The method has revealed that the risk of these sequences could grow to high level if certain specific preventive measures were degraded with time. This study has identified these preventive measures, thus facilitating a rational allocation of resources in regular controls to detect any loss of reliability. The method has proven to have an important practical value and is affordable at hospital level. The elaborated risk-matrix can be easily adapted to local circumstances, in terms of existing controls and safety measures. This approach can help hospitals to identify

  13. Quantitative assessment of skin erythema due to radiotherapy--evaluation of different measurements

    International Nuclear Information System (INIS)

    Background and purpose: Visual assessment is the most common clinical investigation of skin reactions in radiotherapy. Due to the unquantitative and subjective nature of this method additional non-invasive methods are needed for more accurate evaluation of the visible acute adverse skin reactions due to radiotherapy. The purpose of this study was to evaluate a new objective measure with regard to reliability and validity and compare it with an established objective measure and a visual assessment. Patients and methods: A sample of 53 consecutive patients commencing curative tangential radiation therapy to the breast parenchyma were included in the study. The skin area of the treated breast was divided into five sections and assessed individually at 0, 24 and 50 Gy. The RTOG scoring system was used for the visual assessment of the skin reactions. The first objective measure included reflectance spectrometry (DermaSpectrometer) measures at fixed points within the treatment area. For the second objective measure digital images (Camera) were taken with a system using a digital camera and software. The images were analyzed using the Adobe Photoshop 5.0 software program. Results: The results provided significant evidence of the test-retest reliability of the camera. The correlation between the objective measures proved to be significant as the treatment progressed. Conclusions: The results suggest that the camera may be used in a reliable and valid way to measure skin erythema due to radiotherapy

  14. Assessment of induction of secondary tumours due to various radiotherapy modalities

    International Nuclear Information System (INIS)

    One of the objectives of the European Sixth Framework integrated project MAESTRO is to perform an assessment of risk due to various radiotherapy modalities, regarding secondary tumour induction. Initially, the study will focus on cancer of the prostate and the present work represents the first step towards that goal. One of the intended tools, to be used in the assessment, is the Monte Carlo radiation transport code ORANGE. A validation of the ORANGE code's capability to tally dose on a grid superimposed on an existing MCNP geometry is given. Preliminary results on the dose distribution due to conventional radiotherapy treatment of prostate cancer are discussed. Two mathematical models of the patient are proposed and the clinical relevance of the ADAM phantom is investigated. A problem in comparing average doses provided by commercial treatment planning systems and those calculated with Monte Carlo is noticed. The two proposed models are shown to receive a lower dose and average energy deposition than a 'real' patient. (authors)

  15. Three- and four-dimensional ultrasound in fetal echocardiography: an up-to-date overview.

    Science.gov (United States)

    Adriaanse, B M E; van Vugt, J M G; Haak, M C

    2016-09-01

    Congenital heart diseases (CHD) are the most commonly overlooked lesions in prenatal screening programs. Real-time two-dimensional ultrasound (2DUS) is the conventionally used tool for fetal echocardiography. Although continuous improvements in the hardware and post-processing software have resulted in a good image quality even in late first trimester, 2DUS still has its limitations. Four-dimensional ultrasound with spatiotemporal image correlation (STIC) is an automated volume acquisition, recording a single three-dimensional (3D) volume throughout a complete cardiac cycle, which results in a four-dimensional (4D) volume. STIC has the potential to increase the detection rate of CHD. The aim of this study is to provide a practical overview of the possibilities and (dis)advantages of STIC. A review of literature and evaluation of the current status and clinical value of 3D/4D ultrasound in prenatal screening and diagnosis of congenital heart disease are presented. PMID:26963426

  16. The four-dimensional mouse whole-body phantoms and its application in medical imaging research

    International Nuclear Information System (INIS)

    Medical imaging simulation is a powerful tool for characterizing,evaluating,and optimizing medical imaging devices and techniques. A vital aspect of simulation is to have a realistic phantom or model of the subject's anatomy. Four-dimensional mouse whole-body phantoms provide realistic models of the mouse anatomy and physiology for imaging studies. When combined with accurate models for the imaging process,are capable of providing a wealth of realistic imaging data from subjects with various anatomies and motions (cardiac and respiratory) in health and disease. With this ability, the four-dimensional mouse whole-body phantoms have enormous potential to study the effects of anatomical, physiological and physical factors on medical and small animal imaging and to research new instrumentation, image acquisition strategies, image processing, reconstruction methods, image visualization and interpretation techniques. (authors)

  17. Novel four-dimensional autonomous chaotic system generating one-, two-, three- and four-wing attractors

    International Nuclear Information System (INIS)

    In this paper, we propose a novel four-dimensional autonomous chaotic system. Of particular interest is that this novel system can generate one-, two, three- and four-wing chaotic attractors with the variation of a single parameter, and the multi-wing type of the chaotic attractors can be displayed in all directions. The system is simple with a large positive Lyapunov exponent and can exhibit some interesting and complicated dynamical behaviours. Basic dynamical properties of the four-dimensional chaotic system, such as equilibrium points, the Poincaré map, the bifurcation diagram and the Lyapunov exponents are investigated by using either theoretical analysis or numerical method. Finally, a circuit is designed for the implementation of the multi-wing chaotic attractors. The electronic workbench observations are in good agreement with the numerical simulation results. (general)

  18. A symplectic rearrangement of the four dimensional non-geometric scalar potential

    CERN Document Server

    Shukla, Pramod

    2015-01-01

    We present a symplectic rearrangement of the effective four-dimensional non-geometric scalar potential resulting from the type IIB superstring compactification on Calabi Yau orientifolds. The strategy has two main steps. In the first step, we rewrite the four dimensional scalar potential utilizing some interesting flux combinations which we call {\\it new generalized flux orbits}. After invoking a couple of non-trivial symplectic relations, in the second step, we further rearrange all the pieces of scalar potential into a completely `symplectic-formulation' which involves only the symplectic ingredients (such as period matrix etc.) without the need of knowing Calabi Yau metric. Moreover, the scalar potential under consideration is induced by a generic tree level K\\"{a}hler potential and (non-geometric) flux superpotential for arbitrary numbers of complex structure moduli, K\\"ahler moduli and odd-axions. Finally, we exemplify our symplectic formulation for the two well known toroidal examples based on type IIB ...

  19. Rotating system for four-dimensional transverse rms-emittance measurements

    CERN Document Server

    Xiao, C; Du, X N; Gerhard, P; Groening, L; Mickat, S; Vormann, H

    2016-01-01

    Knowledge of the transverse four-dimensional beam rms-parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Of special interest is the removal of inter-plane correlations to reduce the projected emittances. A dedicated ROtating System for Emittance measurements (ROSE) has been proposed, developed, and successfully commissioned to fully determine the four-dimensional beam matrix. This device has been used at the High Charge injector (HLI) at GSI using a beam line which is composed of a skew quadrupole triplet, a normal quadrupole doublet, and ROSE. Mathematical algorithms, measurements, and results for ion beams of 83Kr13+ at 1.4 MeV/u are reported in this paper.

  20. Prospective patient-based assessment of effectiveness of palliative radiotherapy for bone metastases

    International Nuclear Information System (INIS)

    Purpose: The primary objective of this report is to prospectively evaluate pain control provided by palliative radiotherapy for all irradiated patients with bone metastases by using their own assessments. Materials and methods: A prospective database was set up for all patients referred for palliative radiotherapy for bone metastases. Patients were asked to rate their pain intensity using an 11 categorical point scale (0=lack of pain, 10=worst pain imaginable). Analgesic consumption during the preceding 24 h was recorded and converted into equivalent total daily dose of oral morphine. For those who received radiotherapy, follow-up was conducted via telephone interviews at week 1, 2, 4, 8 and 12 post treatment using the same pain scale and analgesic diary. Radiotherapy outcome was initially assessed by pain score alone. Complete response (CR) was defined as a pain score of 0. Partial response (PR) was defined as a reduction of score ≥2 or a≥50% reduction of the pre-treatment pain score. We further analyzed outcomes using integrated pain and analgesic scores. Response was defined as either a reduction of pain score ≥2 with at least no increase in analgesics or at least stable pain score with a ≥50% reduction in analgesic intake. Results: One hundred and five patients were treated with palliative radiotherapy. When response evaluation was by pain score alone, the PR rates at 2, 4, 8 and 12 weeks were 44, 42, 30 and 38%, respectively; while the CR rates were 24, 32, 31 and 29%, respectively. The overall response rate at 12 weeks was 67%. When assessed by the integrated pain and analgesic scores, the response rates were 50, 46, 43 and 43%, respectively. Conclusion: The response rate in our patient population is comparable with those reported in clinical trials. This is important when counselling our patients on the expected effectiveness of radiotherapy outside of clinical trials. Our observations confirm the generalizability of the trials conducted to date

  1. Morphogenesis of an extended phenotype: four-dimensional ant nest architecture

    OpenAIRE

    Minter, Nicholas J.; Franks, Nigel R.; Robson Brown, Katharine A.

    2011-01-01

    Animals produce a variety of structures to modify their environments adaptively. Such structures represent extended phenotypes whose development is rarely studied. To begin to rectify this, we used micro-computed tomography (CT) scanning and time-series experiments to obtain the first high-resolution dataset on the four-dimensional growth of ant nests. We show that extrinsic features within the environment, such as the presence of planes between layers of sediment, influence the architecture ...

  2. Iterative sorting for four-dimensional CT images based on internal anatomy motion

    OpenAIRE

    Zeng, Rongping; Fessler, Jeffrey A.; Balter, James M.; Balter, Peter A.

    2008-01-01

    Current four-dimensional (4D) computed tomography (CT) imaging techniques using multi-slice CT scanners require retrospective sorting of the reconstructed two-dimensional (2D) CT images. Most existing sorting methods depend on externally monitored breathing signals recorded by extra instruments. External signals may not always accurately capture the breathing status and may lead to severe discontinuity artifacts in the sorted CT volumes. This paper describes a method to find the temporal corr...

  3. Instability of a four-dimensional de Sitter black hole with a conformally coupled scalar field

    OpenAIRE

    Harper, Tom J. T.; Thomas, Paul A.; Winstanley, Elizabeth(Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, United Kingdom); Young, Phil M.

    2003-01-01

    We study the stability of new neutral and electrically charged four-dimensional black hole solutions of Einstein's equations with a positive cosmological constant and conformally coupled scalar field. The neutral black holes are always unstable. The charged black holes are also shown analytically to be unstable for the vast majority of the parameter space of solutions, and we argue using numerical techniques that the configurations corresponding to the remainder of the parameter space are als...

  4. Statistical Entropy of Nonextremal Four-Dimensional Black Holes and U-Duality

    International Nuclear Information System (INIS)

    We identify the states in string theory which are responsible for the entropy of near-extremal rotating four-dimensional black holes in N=8 supergravity. For black holes far from extremality (with no rotation), the Bekenstein-Hawking entropy is exactly matched by a mysterious duality invariant extension of the formulas derived for near-extremal black holes states. copyright 1996 The American Physical Society

  5. Solutions of the generalized Weierstrass representation in four-dimensional Euclidean space

    OpenAIRE

    P. Bracken; Grundland, A. M.

    2003-01-01

    Several classes of solutions of the generalized Weierstrass system, which induces constant mean curvature surfaces into four-dimensional Euclidean space are constructed. A gauge transformation allows us to simplify the system considered and derive factorized classes of solutions. A reduction of the generalized Weierstrass system to decoupled CP^1 sigma models is also considered. A new procedure for constructing certain classes of solutions, including elementary solutions (kinks and bumps) and...

  6. Non-diagonal four-dimensional cohomogeneity-one Einstein metrics in various signatures

    CERN Document Server

    Dunajski, Maciej

    2016-01-01

    Most known four-dimensional cohomogeneity-one Einstein metrics are diagonal in the basis defined by the left-invariant one-forms, though some essentially non-diagonal ones are known. We consider the problem of explicitly seeking non-diagonal Einstein metrics, and we find solutions which in some cases exhaust the possibilities. In particular we construct new examples of neutral signature non--diagonal Bianchi type VIII Einstein metrics with self--dual Weyl tensor.

  7. A New Class of Four-Dimensional N=1 Supergravity with Non-minimal Derivative Couplings

    CERN Document Server

    Farakos, Fotis; Kehagias, Alex; Saridakis, Emmanuel N

    2012-01-01

    In the N=1 four-dimensional new-minimal supergravity framework, we supersymmetrise the coupling of the scalar kinetic term to the Einstein tensor. This coupling, although introduces a non-minimal derivative interaction of curvature to matter, it does not introduce harmful higher-derivatives. For this construction, we employ off-shell chiral and real linear multiplets. Physical scalars are accommodated in the chiral multiplet whereas curvature resides in a linear one.

  8. Four-dimensional SAR Imaging Algorithm Based on Iterative Reconstruction of Magnitude and Phase

    OpenAIRE

    Ren Xiaozhen; Yang Ruliang

    2016-01-01

    Observation data obtained from the Four-Dimensional (4D) Synthetic Aperture Radar (SAR) system is sparse and non-uniform in the baseline-time plane. Hence, the imaging results acquired by traditional Fourier-based methods are limited by high side lobes. Compressive Sensing (CS) is a recently proposed technique that allows for the recovery of an unknown sparse signal with overwhelming probability from very limited samples. However, the standard CS framework has been developed for real-valued s...

  9. Cross-cultural validation of the Turkish Four-Dimensional Symptom Questionnaire (4DSQ) using differential item and test functioning (DIF and DTF) analysis

    OpenAIRE

    Terluin, Berend; Unalan, Pemra C.; Turfaner Sipahioğlu, Nurver; Arslan Özkul, Seda; van Marwijk, Harm W. J.

    2016-01-01

    Background The Four-Dimensional Symptom Questionnaire (4DSQ) is originally a Dutch 50 item questionnaire developed in primary care to assess distress, depression, anxiety and somatization. We aimed to develop and validate a Turkish translation of the 4DSQ. Methods The questionnaire was translated using forward and backward translation, and pilot testing. Turkish 4DSQ-data were collected in 352 consecutive adult primary care patients. For comparison, gender and age matched Dutch reference data...

  10. Quantitative MR imaging in planning and assessing novel cancer treatments Radiotherapy

    CERN Document Server

    Baustert, I C

    2001-01-01

    Novel treatments in cancer, like conformal radiotherapy and anticancer drugs, require new MRI techniques to assess their benefits and potential. In conformal radiotherapy, MRI can be used to measure the shape and dose of the conformed radiation field in dose sensitive gel test-objects thus validating the predicted dose computed by complex programs. In antiangiogenic drug treatment, the vascular dysfunction of the tumour can be assessed by MRI prior to treatment. Response to treatment may also be monitored by measuring the changes in vascular function. In this thesis, MRI of polyacrylamide gels is investigated as a 3D dosimeter for conformal radiotherapy treatment planning. Quantitative MRI sequences capable of measuring the wide range of T2 values typically expected in gel dosimetry, are identified. Different T2 measurement methods are compared in terms of accuracy, signal to noise ratio and acquisition time. Examples of a complex dose distribution in 2D and 3D are presented and compared to the planned dose p...

  11. Assessment of safety culture within the radiotherapy department of the Bordeaux University Hospital Centre

    International Nuclear Information System (INIS)

    The assessment of the safety culture within a radiotherapy department has been performed by using a Safety Attitudes Questionnaire (SAQ). It assesses the safety environment, the team cooperation quality, the satisfaction related to professional activity, the approval of management actions, the perception of the work environment quality and of logistic support, and the acknowledgment of the influence of stress on performance. The survey has been performed before and after the support intervention of a hospital audit and expertise mission in relationship with the National cancer Institute (Inca). The comparison of results before and after this support intervention shows a general score improvement for the SAQ. Short communication

  12. Prospective assessment of the salivary function by parotid scintigraphy after radiotherapy of 27 nasopharyngeal cancers; evaluation prospective de la fonction salivaire par scintigraphie parotidienne apres radiotherapie de 27 cancers du nasopharynx

    Energy Technology Data Exchange (ETDEWEB)

    Mnejja, W.; Ghorbal, L.; Daoud, J. [Service de radiotherapie oncologique, CHU Habib-Bourguiba, Sfax (Tunisia); Kallel, F.; Guermazi, F. [Service de medecine nucleaire, CHU Habib-Bourguiba, Sfax (Tunisia); Frikha, M. [Service de carcinologie medicale, CHU Habib-Bourguiba, Sfax (Tunisia)

    2011-10-15

    As xerostomia is the main complication after radiotherapy of nasopharyngeal carcinomas, and affects life quality, this study aims at objectively assess the salivary function after radiotherapy of a nasopharyngeal cancer by parotid scintigraphy. 27 seven patients have been treated by radiotherapy with or without chemotherapy. Results are analyzed in terms of salivary toxicity, change of secretion function. No correlation was found between the xerostomia severity and scintigraphy results. Short communication

  13. Investigation of a Patient Reported Outcome tool to assess radiotherapy-related toxicity prospectively in patients with lung cancer

    International Nuclear Information System (INIS)

    Background and purpose: There is a paucity of data regarding the feasibility and relevance of Patient Reported Outcome (PRO) tools to assess radiotherapy-related toxicity in lung cancer. Material and methods: From January to June 2013, lung cancer patients undergoing thoracic radiotherapy/chemo-radiotherapy completed nine patient-adapted Common Terminology Criteria for Adverse Events (CTCAE), the European Organisation for Research and Treatment of Cancer Quality of Life (QoL) questionnaire and the Hospital Anxiety and Depression Scale (HADS) at baseline, the end of radiotherapy and at follow-up. Clinicians completed the same CTCAE items and agreement between patients’ and clinicians’ reporting was assessed using weighted kappa coefficients. QoL and HADS scores were correlated with the patients’ and clinicians’ reported toxicity. Results: 70/116 patients completed the questionnaires for at least one time point excluding baseline. Agreement between patients’ and clinicians’ reported toxicity ranged from slight to substantial. Most discrepancies were within one grade and patients reported greater severity than clinicians for most symptoms. QoL and HADS scores were more strongly correlated with the patients’ compared to clinicians’ matching toxicity reports. The PRO tool was found to be statistically reliable. Conclusions: The use of a PRO tool in lung cancer radiotherapy is feasible, reliable and acceptable to patients. PROs should be integrated in future clinical trials evaluating new radiotherapy approaches to assess toxicity

  14. Three-dimensional dynamics of four-dimensional topological BF theory with boundary

    International Nuclear Information System (INIS)

    We consider the four-dimensional (4D) abelian topological BF theory with a planar boundary, following Symanzik's method. We find the most general boundary conditions compatible with the field equations broken by the boundary. The residual gauge invariance is described by means of two Ward identities which generate a current algebra. We interpret this algebra as canonical commutation relations of fields, which we use to construct a 3D Lagrangian. As a remarkable by-product, we find a (unique) boundary condition which can be read as a duality relation between 3D dynamical variables. (paper)

  15. Four-Dimensional Effective Supergravity and Soft Terms in M-Theory

    OpenAIRE

    Choi, Kiwoon; Kim, Hang Bae; Munoz, Carlos

    1997-01-01

    We provide a simple macroscopic analysis of the four-dimensional effective supergravity of the Ho\\v{r}ava-Witten M-theory which is expanded in powers of $\\kappa^{2/3}/\\rho V^{1/3}$ and $\\kappa^{2/3}\\rho/V^{2/3}$ where $\\kappa^2$, $V$ and $\\rho$ denote the eleven-dimensional gravitational coupling, the Calabi-Yau volume and the eleventh length respectively. Possible higher order terms in the K\\"ahler potential are identified and matched with the heterotic string corrections. In the context of ...

  16. Applications of the Ashtekar gravity to four-dimensional hyperkaehler geometry and Yang endash Mills instantons

    International Nuclear Information System (INIS)

    The Ashtekar endash Jacobson endash Smolin endash Mason endash Newman equations are used to construct the hyperkaehler metrics on four-dimensional manifolds. These equations are closely related to anti-self-dual Yang endash Mills equations of the infinite-dimensional gauge Lie algebras of all volume-preserving vector fields. Several examples of hyperkaehler metrics are presented through the reductions of anti-self-dual connections. For any gauge group anti-self-dual connections on hyperkaehler manifolds are constructed using the solutions of both Nahm and Laplace equations. copyright 1997 American Institute of Physics

  17. Choice of evolutional parameter within a framework of four-dimensional symmetry

    International Nuclear Information System (INIS)

    Within the context of the variational principle, there is the freedom to choose specific evolutional parameters. Different parameters can be associated with physical time, while allowing the physical laws to preserve the property of four-dimensional symmetry. In this sense, the concept of time has flexibility. Besides proper time and relativistic time, another natural choice emerges, which is called the generalized Galilean time. We study the impact of this choice here. This approach provides a deeper understanding of the theory of special relativity, and it also provides a new basis to study other space-time theories

  18. Quasinormal modes of four-dimensional topological nonlinear charged Lifshitz black holes

    Energy Technology Data Exchange (ETDEWEB)

    Becar, Ramon [Universidad Cato lica de Temuco, Departamento de Ciencias Matematicas y Fisicas, Temuco (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)

    2016-02-15

    We study scalar perturbations of four- dimensional topological nonlinear charged Lifshitz black holes with spherical and plane transverse sections, and we find numerically the quasinormal modes for scalar fields. Then we study the stability of these black holes under massive and massless scalar field perturbations. We focus our study on the dependence of the dynamical exponent, the nonlinear exponent, the angular momentum, and the mass of the scalar field in the modes. It is found that the modes are overdamped, depending strongly on the dynamical exponent and the angular momentum of the scalar field for a spherical transverse section. In contrast, for plane transverse sections the modes are always overdamped. (orig.)

  19. Analysis of two-torus in a new four-dimensional autonomous system

    International Nuclear Information System (INIS)

    In this paper, we report the dynamical behaviours of a four-dimensional autonomous continuous dissipative system analysed when the parameter is varied in the range we are interested in. The system changes its dynamical modes between periodic motion and quasiperiodic motion. Furthermore, the existence of two-torus is investigated numerically by means of Lyapunov exponents. By taking advantage of phase portraits and Poincare sections, two types of the two-torus are observed and proved to have the structure of ring torus and horn torus, both of which are known to be the standard tori

  20. Observations on the space of four dimensional string and M theory vacua

    International Nuclear Information System (INIS)

    The space of four dimensional string and M theory vacua with non-Abelian gauge symmetry, chiral fermions and unbroken supersymmetry beyond the electroweak scale appears to be a disconnected space whose different components represent distinct universality classes of vacua. Calculating statistical distributions of physical observables a la Douglas therefore requires that the distinct components are carefully accounted for. We highlight some classes of vacua which deserve further study and suggest an argument which may serve to rule out vacua which are small perturbations of supersymmetric AdS4. (author)

  1. The pedagogical value of the four-dimensional picture: I. Relativistic mechanics of point particles

    International Nuclear Information System (INIS)

    In this paper we outline two subjects of relativistic mechanics: (i) the set of allowable world lines, and (ii) the origin of the relativistic law of dynamics governing point particles. We show that: (i) allowable world lines in the classical theory of particles and fields are quite simple geometric objects as opposed to their associated three-dimensional trajectories; and (ii) Newton’s second law requires neither modification nor generalization, it should only be smoothly embedded in the four-dimensional geometry of Minkowski spacetime to yield the dynamical law for relativistic particles. (paper)

  2. The pedagogical value of the four-dimensional picture: I. Relativistic mechanics of point particles

    Science.gov (United States)

    Kosyakov, B. P.

    2014-03-01

    In this paper we outline two subjects of relativistic mechanics: (i) the set of allowable world lines, and (ii) the origin of the relativistic law of dynamics governing point particles. We show that: (i) allowable world lines in the classical theory of particles and fields are quite simple geometric objects as opposed to their associated three-dimensional trajectories; and (ii) Newton’s second law requires neither modification nor generalization, it should only be smoothly embedded in the four-dimensional geometry of Minkowski spacetime to yield the dynamical law for relativistic particles.

  3. Chiral four-dimensional F-theory compactifications with SU(5) and multiple U(1)-factors

    OpenAIRE

    Mirjam Cvetič; Antonella Grassi; Denis Klevers; Hernan Piragua

    2014-01-01

    We develop geometric techniques to determine the spectrum and the chiral indices of matter multiplets for four-dimensional F-theory compactifications on elliptic Calabi-Yau fourfolds with rank two Mordell-Weil group. The general elliptic fiber is the Calabi-Yau onefold in dP 2 . We classify its resolved elliptic fibrations over a general base B . The study of singularities of these fibrations leads to explicit matter representations, that we determine both for U(1) × U(1) and SU(5) × U(1) × U...

  4. Quality of life in patients with oropharynx carcinomas: assessment after accelerated radiotherapy with or without chemotherapy versus radical surgery and postoperative radiotherapy

    OpenAIRE

    Allal, Abdelkarim Said; Nicoucar, Kevin; Mach, Nicolas; Dulguerov, Pavel

    2003-01-01

    In oropharyngeal carcinomas, it is assumed that the effectiveness of the different treatment approaches is roughly equivalent, whereas the functional outcome after radical radiotherapy (RT) is superior to that associated with primary surgery. The aim of this study is to assess quality of life (QoL) outcomes of patients after two treatment strategies: radical surgery with postoperative RT and accelerated concomitant boost RT with or without chemotherapy.

  5. Assessment of quality of life after radical radiotherapy for prostate cancer

    International Nuclear Information System (INIS)

    The objective was to assess the quality of life (QoL) of patients with localized prostate cancer (LPC) after treatment by radical radiotherapy (RR). An ''ad hoc'' self-administered questionnaire was developed, which comprised a series of 41 items grouped into seven subscales reflecting the main QoL domains, and the questionnaire's psychometric properties were assessed. Ninety patients (76%) completed the questionnaire; because 20 of them were also treated with hormonal therapy, QoL was assessed only in the remaining 70 patients, to avoid confusion. The assessment of the psychometric properties showed that the questionnaire was valid and reliable (Cronbach's α coefficient >0.8 for each subscale). The main side effects of RR were urinary symptoms and sexual impairment, while physical, psychological and relational well-being were good. The degree of information available about the therapy and the disease seemed to play a major role in the patients' QoL adjustment after RR. (Author)

  6. An introduction to an alternative four-dimensional formalism of the special theory of relativity

    International Nuclear Information System (INIS)

    A formulation of the four-dimensional vector laws of physics which emphasizes the transformation of position and time using the four-vectors (R', 0) and (0, ct') is presented. One goal of the formalism is to incorporate the Lorentz co-ordinate transformation of measured position and time intervals. Another goal is to generate vector laws of physics in both three- and four-dimensional formats. A definition of the electrostatic field is introduced which can be inserted into a four-vector allowing Gauss' law to be interpreted as both covariant and numerically invariant. Consistent with the definition of the electrostatic field are revised definitions of force, magnetic field, charge density and current. The alternative formulation of standard theory suggests that the concept of geometric invariance was neglected in deriving the three-dimensional vector laws of physics. The Minkowski formulation and the alternative formulation together illustrate two basic ways of transforming length and time intervals in the special theory of relativity

  7. Four-dimensional conversion for spiritual leadership development: A missiological approach for African churches

    Directory of Open Access Journals (Sweden)

    Kalemba Mwambazambi

    2014-04-01

    Full Text Available The process of a four-dimensional conversion and/or transformation strives in helping the leadership of an organisation, especially such as the church, with practical ways that may lead to the development of an effective leadership by observing the four important aspects of human spirituality as elaborated on in the article. The spiritual, intellectual, moral and socio-political dimensions of the transformation can be catered for so that the complete inner being of humans, as well as their social and political attitudes and behaviours, can equally be transformed to maximum spiritual, personal and socio-political profitability. Mutombo-Mukendi demonstrates that the need for a spiritual leadership that can contribute to an effective transformation of Africa is dire, both for the church and the larger community. The real challenge is how to develop such leadership. This article provides intentional and practical ways that may lead to the development of the needed leadership. Four-dimensional transformation of people can be planned and carried out both in the church arena and in the surrounding communities. Skills development and transfer can also take place when skilled people from the church work with unskilled people from the community.

  8. A novel four-dimensional analytical approach for analysis of complex samples.

    Science.gov (United States)

    Stephan, Susanne; Jakob, Cornelia; Hippler, Jörg; Schmitz, Oliver J

    2016-05-01

    A two-dimensional LC (2D-LC) method, based on the work of Erni and Frei in 1978, was developed and coupled to an ion mobility-high-resolution mass spectrometer (IM-MS), which enabled the separation of complex samples in four dimensions (2D-LC, ion mobility spectrometry (IMS), and mass spectrometry (MS)). This approach works as a continuous multiheart-cutting LC system, using a long modulation time of 4 min, which allows the complete transfer of most of the first - dimension peaks to the second - dimension column without fractionation, in comparison to comprehensive two-dimensional liquid chromatography. Hence, each compound delivers only one peak in the second dimension, which simplifies the data handling even when ion mobility spectrometry as a third and mass spectrometry as a fourth dimension are introduced. The analysis of a plant extract from Ginkgo biloba shows the separation power of this four-dimensional separation method with a calculated total peak capacity of more than 8700. Furthermore, the advantage of ion mobility for characterizing unknown compounds by their collision cross section (CCS) and accurate mass in a non-target approach is shown for different matrices like plant extracts and coffee. Graphical abstract Principle of the four-dimensional separation. PMID:27038056

  9. The Radiobiological Basis for Improvements in Radiotherapy and Low Dose Risk Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Hei, Tom K

    2009-12-09

    Overall Goal: This conference grant was proposed to organize and host an international conference at Columbia University in New York to critically assess the cellular and molecular signaling events and tissue response following radiation damage. The conference would also serve as a venue to play tribute to the more than forty years contributions made by Professor Eric J. Hall to the radiation biology field. The goals of the meeting were to examine tumor hypoxia and sensitizer development; recent advances made in clinical radiotherapy; addressed several low dose phenomena, including genomic instability and bystander effects that are important in radiation risk assessment. Study and Results: The symposium was held on October 13th and 14th, 2008 at the Alfred Lerner Hall in the Morningside campus of Columbia University. The symposium, entitled “From Beans to Genes: A Forty Year Odyssey in Radiation Biology” was attended by more than 120 faculty, scientists, clinicians, fellows and students. The symposium, spanned over a day and a half, covered four scientific themes. These included tumor hypoxia and radiosensitizers; low dose radiation response; radiation biology in the practice of radiotherapy, and radiation hazard in space and genetic predisposition to cancer. The program of the symposium is as follow:

  10. Fluctuation in measurements of pulmonary nodule under tidal volume ventilation on four-dimensional computed tomography: preliminary results

    International Nuclear Information System (INIS)

    The present study aimed to assess the feasibility of four-dimensional (4D) chest computed tomography (CT) under tidal volume ventilation and the impact of respiratory motion on quantitative analysis of CT measurements. Forty-four pulmonary nodules in patients with metastatic disease were evaluated. CT examinations were performed using a 256 multidetector-row CT (MDCT) unit. Volume data were obtained from the lower lung fields (128 mm) above the diaphragm during dynamic CT acquisition. The CT parameters used were 120 kV, 100 or 150 mA, 0.5 s-1, and 0.5 mm collimation. Image data were reconstructed every 0.1 s during one respiratory cycle by a 180 reconstruction algorithm for four independent fractions of the respiratory cycle. Pulmonary nodules were measured along their longest and shortest axes using electronic calipers. Automated volumetry was assessed using commercially available software. The diameters of long and short axes in each frame were 9.0-9.6 mm and 7.1-7.5 mm, respectively. There was fluctuation of the long axis diameters in the third fraction. The mean volume in each fraction ranged from 365 to 394 mm3. Statistically significant fluctuation was also found in the third fraction. 4D-CT under tidal volume ventilation is feasible to determine diameter or volume of the pulmonary nodule. (orig.)

  11. Phase II Study to Assess the Efficacy of Hypofractionated Stereotactic Radiotherapy in Patients With Large Cavernous Sinus Hemangiomas

    International Nuclear Information System (INIS)

    Purpose: Cavernous sinus hemangioma is a rare vascular tumor. The direct microsurgical approach usually results in massive hemorrhage. Although radiosurgery plays an important role in managing cavernous sinus hemangiomas as a treatment alternative to microsurgery, the potential for increased toxicity with single-session treatment of large tumors is a concern. The purpose of this study was to assess the efficacy of hypofractionated stereotactic radiotherapy in patients with large cavernous sinus hemangiomas. Methods: Fourteen patients with large (volume >20 cm3) cavernous sinus hemangiomas were enrolled in a prospective Phase II study between December 2007 and December 2010. The hypofractionated stereotactic radiotherapy dose was 21 Gy delivered in 3 fractions. Results: After a mean follow-up of 15 months (range, 6–36 months), the magnetic resonance images showed a mean of 77% tumor volume reduction (range, 44–99%). Among the 6 patients with cranial nerve impairments before hypofractionated stereotactic radiotherapy, 1 achieved symptomatic complete resolution and 5 had improvement. No radiotherapy-related complications were observed during follow-up. Conclusion: Our current experience, though preliminary, substantiates the role of hypofractionated stereotactic radiotherapy for large cavernous sinus hemangiomas. Although a longer and more extensive follow-up is needed, hypofractionated stereotactic radiotherapy of 21 Gy delivered in 3 fractions is effective in reducing the tumor volume without causing any new deficits and can be considered as a treatment modality for large cavernous sinus hemangiomas.

  12. Ground-state projection multigrid for propagators in four-dimensional SU (2) gauge fields

    International Nuclear Information System (INIS)

    The ground-state projection multigrid method is studied for computations of slowly decaying bosonic propagators in four-dimensional SU (2) lattice gauge theory. The defining eigenvalue equation for the restriction operator C is solved exactly. With the Galerkin choice A=C* for the interpolation operator, the critical exponent z is not reduced in nontrivial gauge fields. Nevertheless, a considerable speedup is obtained compared to conventional relaxation, and the conjugate gradient algorithm is outperformed. Simulations with an 'optimal' interpolation kernel A eliminate critical slowing down for any value of the gauge coupling. This proves that ground-state projection is a good choice of C (i.e., of the blockspin). (orig.)

  13. Four-dimensional tracking of spatially incoherent illuminated samples using self-interference digital holography

    Science.gov (United States)

    Man, Tianlong; Wan, Yuhong; Wu, Fan; Wang, Dayong

    2015-11-01

    We present a new method for the four-dimensional tracking of a spatially incoherent illuminated object. Self-interference digital holography is utilized for recording the hologram of the spatially incoherent illuminated object. Three-dimensional spatial coordinates encoded in the hologram are extracted by holographic reconstruction procedure and tracking algorithms, while the time information is reserved by the single-shot configuration. Applications of the holographic tracking methods are expanded to the incoherent imaging areas. Speckles and potential damage to the samples of the coherent illuminated tracking methods are overcome. Results on the quantitative tracking of three-dimensional spatial position over time are reported. In practical, living zebra fish larva is used to demonstrate one of the applications of the method.

  14. Five-brane thresholds and membrane instantons in four-dimensional heterotic M-theory

    International Nuclear Information System (INIS)

    The effective four-dimensional supergravity of M-theory compactified on the orbifold S1/Z2 and a Calabi-Yau threefold includes in general moduli supermultiplets describing massless modes of five-branes. For each brane, one of these fields corresponds to fluctuations along the interval. The five-brane also leads to modifications of the anomaly-cancelling terms in the eleven-dimensional theory, including gauge contributions located on their world-volumes. We obtain the interactions of the brane 'interval modulus' predicted by these five-brane-induced anomaly-cancelling terms and we construct their effective supergravity description. In the condensed phase, these interaction terms generate an effective non-perturbative superpotential which can also be interpreted as instanton effects of open membranes stretching between five-branes and the S1/Z2 fixed hyperplanes. Aspects of the vacuum structure of the effective supergravity are also briefly discussed

  15. A four-dimensional primitive equation model for coupled coastal-deep ocean studies

    Science.gov (United States)

    Haidvogel, D. B.

    1981-01-01

    A prototype four dimensional continental shelf/deep ocean model is described. In its present form, the model incorporates the effects of finite amplitude topography, advective nonlinearities, and variable stratification and rotation. The model can be forced either directly by imposed atmospheric windstress and surface pressure distributions, and energetic mean currents imposed by the exterior oceanic circulation; or indirectly by initial distributions of shoreward propagation mesoscale waves and eddies. To avoid concerns over the appropriate specification of 'open' boundary conditions on the cross-shelf and seaward model boundaries, a periodic channel geometry (oriented along-coast) is used. The model employs a traditional finite difference expansion in the cross-shelf direction, and a Fourier (periodic) representation in the long-shelf coordinate.

  16. A time-parallel approach to strong-constraint four-dimensional variational data assimilation

    Science.gov (United States)

    Rao, Vishwas; Sandu, Adrian

    2016-05-01

    A parallel-in-time algorithm based on an augmented Lagrangian approach is proposed to solve four-dimensional variational (4D-Var) data assimilation problems. The assimilation window is divided into multiple sub-intervals that allows parallelization of cost function and gradient computations. The solutions to the continuity equations across interval boundaries are added as constraints. The augmented Lagrangian approach leads to a different formulation of the variational data assimilation problem than the weakly constrained 4D-Var. A combination of serial and parallel 4D-Vars to increase performance is also explored. The methodology is illustrated on data assimilation problems involving the Lorenz-96 and the shallow water models.

  17. Structures of larger proteins in solution: Three- and four-dimensional heteronuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gronenborn, A.M.; Clore, G.M. [National Institutes of Health, Bethesda, MD (United States)

    1994-12-01

    Complete understanding of a protein`s function and mechanism of action can only be achieved with a knowledge of its three-dimensional structure at atomic resolution. At present, there are two methods available for determining such structures. The first method, which has been established for many years, is x-ray diffraction of protein single crystals. The second method has blossomed only in the last 5 years and is based on the application of nuclear magnetic resonance (NMR) spectroscopy to proteins in solution. This review paper describes three- and four-dimensional NMR methods applied to protein structure determination and was adapted from Clore and Gronenborn. The review focuses on the underlying principals and practice of multidimensional NMR and the structural information obtained.

  18. Live four-dimensional optical coherence tomography reveals embryonic cardiac phenotype in mouse mutant

    Science.gov (United States)

    Lopez, Andrew L., III; Wang, Shang; Larin, Kirill V.; Overbeek, Paul A.; Larina, Irina V.

    2015-09-01

    Efficient phenotyping of developmental defects in model organisms is critical for understanding the genetic specification of normal development and congenital abnormalities in humans. We previously reported that optical coherence tomography (OCT) combined with live embryo culture is a valuable tool for mouse embryo imaging and four-dimensional (4-D) cardiodynamic analysis; however, its capability for analysis of mouse mutants with cardiac phenotypes has not been previously explored. Here, we report 4-D (three-dimensional+time) OCT imaging and analysis of the embryonic heart in a Wdr19 mouse mutant, revealing a heart looping defect. Quantitative analysis of cardiac looping revealed a statistically significant difference between mutant and control embryos. Our results indicate that live 4-D OCT imaging provides a powerful phenotyping approach to characterize embryonic cardiac function in mouse models.

  19. Statistical Entropy of Four-Dimensional Rotating Black Holes from Near-Horizon Geometry

    International Nuclear Information System (INIS)

    We show that a class of four-dimensional rotating black holes allow five-dimensional embeddings as black rotating strings. Their near-horizon geometry factorizes locally as a product of the three-dimensional anti-de Sitter space-time and a two-dimensional sphere (AdS3xS2 ), with angular momentum encoded in the global space-time structure. Following the observation that the isometries on the AdS3 space induce a two-dimensional (super)conformal field theory on the boundary, we reproduce the microscopic entropy with the correct dependence on the black hole angular momentum. copyright 1999 The American Physical Society

  20. Flame four-dimensional deflection tomography with compressed-sensing-revision reconstruction

    Science.gov (United States)

    Zhang, Bin; Zhao, Minmin; Liu, Zhigang; Wu, Zhaohang

    2016-08-01

    Deflection tomography with limited angle projections was investigated to visualize a premixed flame. A projection sampling system for deflection tomography was used to obtain chronological deflectogram arrays at six view angles with only a pair of gratings. A new iterative reconstruction algorithm with deflection angle compressed-sensing revision was developed to improve reconstruction-distribution quality from incomplete projection data. Numerical simulation and error analysis provided a good indication of algorithm precision and convergence. In the experiment, 150 fringes were processed, and temperature distributions in 20 cross-sections were reconstructed from projection data in four instants. Four-dimensional flame structures and temperature distributions in the flame interior were visualized using the visualization toolkit. The experimental reconstruction was then compared with the result obtained from computational fluid dynamic analysis.

  1. Metallic phase of the quantum Hall effect in four-dimensional space

    Science.gov (United States)

    Edge, Jonathan; Tworzydlo, Jakub; Beenakker, Carlo

    2013-03-01

    We study the phase diagram of the quantum Hall effect in four-dimensional (4D) space. Unlike in 2D, in 4D there exists a metallic as well as an insulating phase, depending on the disorder strength. The critical exponent ν ~ 1 . 2 of the diverging localization length at the quantum Hall insulator-to-metal transition differs from the semiclassical value ν = 1 of 4D Anderson transitions in the presence of time-reversal symmetry. Our numerical analysis is based on a mapping of the 4D Hamiltonian onto a 1D dynamical system, providing a route towards the experimental realization of the 4D quantum Hall effect. NanoCTM, FOM/NWO, ERC

  2. Four-dimensional multiphoton microscopy with time-correlated single-photon counting.

    Science.gov (United States)

    Schönle, A; Glatz, M; Hell, S W

    2000-12-01

    We report on the implementation of fluorescence-lifetime imaging in multiphoton excitation microscopy that uses PC-compatible modules for time-correlated single-photon counting. Four-dimensional data stacks are produced with each pixel featuring fluorescence-decay curves that consist of as many as 4096 bins. Fluorescence lifetime(s) and their amplitude(s) are extracted by statistical methods at each pixel or in arbitrarily defined regions of interest. When employing an avalanche photodiode the width of the temporal response function is 420 ps. Although this response confines the temporal resolution to values greater than several hundreds of picoseconds, the lifetime precision is determined by the signal-to-noise ratio and can be in the range of tens of picosconds. Lifetime changes are visualized in pulsed-laser-deposited fluorescent layers as well as in cyan fluorescent proteins that transfer energy to yellow fluorescent proteins in live mammalian cells. PMID:18354639

  3. Four-dimensionally coded PSK systems for combatting effects of severe ISI and CCI

    Science.gov (United States)

    Fang, R.; Lee, W.

    A combined forward error correction (FEC) coding and modulation technique is proposed for transmissions over four-dimensional (4-D) channels that are interference and noise limited. Improved error performance is achieved by 4-D channel coding, with the expanded signal set in a manner similar to Ungerboeck's set-partitioning method, which maximizes the free Euclidean distance. Lower bounds on free Euclidean distance at the output of the 4-D modulator are derived for evaluating the asymptotic performance. As an example, a rate 2/3 convolutional encoder combined with a 4-D coded QPSK signal could yield an Eb/No gain of about 3 to 4 dB over an uncoded two-dimensional (2-D) BPSK system. Performance over a linear channel in the presence of thermal noise, intersymbol interference (ISI), and co-channel interference (CCI) is also evaluated.

  4. Rainfall Assimilation Using a New Four-Dimensional Variational Method: A Single-Point Observation Experiment

    Institute of Scientific and Technical Information of China (English)

    LIU Juanjuan; WANG Bin

    2011-01-01

    Accurate forecast of rainstorms associated with the mei-yu front has been an important issue for the Chinese economy and society. In July 1998 a heavy rainstorm hit the Yangzi River valley and received widespread attention from the public because it caused catastrophic damage in China. Several numerical studies have shown that many forecast models, including Pennsylvania State University National Center for Atmospheric Research's fifth-generation mesoscale model (MM5), failed to simulate the heavy precipitation over the Yangzi River valley. This study demonstrates that with the optimal initial conditions from the dimension-reduced projection four-dimensional variational data assimilation (DRP-4DVar) system, MM5 can successfully reproduce these observed rainfall amounts and can capture many important mesoscale features, including the southwestward shear line and the low-level jet stream. The study also indicates that the failure of previous forecasts can be mainly attributed to the lack of mesoscale details in the initial conditions of the models.

  5. Universal time versus relativistic time in four-dimensional symmetry framework

    International Nuclear Information System (INIS)

    A new four-dimensional symmetry framework with a universal time is investigated which can be realized by a radioactive clock--the measured survival fraction of unstable particles gives the elapsed time. The world picture turns out to be quite different from that in special relativity. The general space-light transformation and the nonuniversal speed of light in this framework are discussed. The difference between the one-way speed and the two-way speed of a light signal is considered in detail. Moreover, the discussion sheds light on the connection between the universality of the light speed and the clock which does not read universal time. The relation with special relativity theory is examined in a few cases

  6. Ultrafast core-loss spectroscopy in four-dimensional electron microscopy

    Directory of Open Access Journals (Sweden)

    Renske M. van der Veen

    2015-03-01

    Full Text Available We demonstrate ultrafast core-electron energy-loss spectroscopy in four-dimensional electron microscopy as an element-specific probe of nanoscale dynamics. We apply it to the study of photoexcited graphite with femtosecond and nanosecond resolutions. The transient core-loss spectra, in combination with ab initio molecular dynamics simulations, reveal the elongation of the carbon-carbon bonds, even though the overall behavior is a contraction of the crystal lattice. A prompt energy-gap shrinkage is observed on the picosecond time scale, which is caused by local bond length elongation and the direct renormalization of band energies due to temperature-dependent electron–phonon interactions.

  7. New supersymmetric black holes in four-dimensional N = 2 supergravity

    Science.gov (United States)

    Mandal, Taniya; Tripathy, Prasanta K.

    2016-05-01

    In this paper, we consider the four-dimensional N = 2 supergravity theory arising from the compactification of type IIA string theory on a Calabi-Yau manifold. We analyze the supersymmetric flow equations for static, spherically symmetric, single-centered black holes. These flow equations are solved by a set of algebraic equations involving the holomorphic sections and harmonic functions. We examine black hole configurations with D0-D4-D6 charge for which the most general solution of these algebraic equations are considered. Though the black hole solution is unique for a given value of the charges, we find new phases of the black hole solutions upon varying them.

  8. On the existence of rigid spheres in four-dimensional spacetime manifolds

    CERN Document Server

    Gittel, Hans-Peter; Kijowski, Jerzy

    2015-01-01

    This paper deals with the generalization of usual round spheres in the flat Minkowski spacetime to the case of a generic four-dimensional spacetime manifold $M$. We consider geometric properties of sphere-like submanifolds in $M$ and introduce conditions on external curvature and torsion, which lead to a definition of a {\\em rigid sphere}. The main result is a local existence theorem concernig such spheres. For this purpose we apply the surjective implicit function theorem. The proof is based on a detailed analysis of the linearized problem and leads to an eight-parameter family of solutions in case when the metric tensor $g$ of $M$ is from a certain neighbourhood of the flat Minkowski metric. This contribution continues the study of rigid spheres in (Class. Quantum Grav. \\textbf{30} (2013), 175010, doi:10.1088/0264-9381/30/17/175010, 18 pp.).

  9. Berry curvature and four-dimensional monopoles in the relativistic chiral kinetic equation.

    Science.gov (United States)

    Chen, Jiunn-Wei; Pu, Shi; Wang, Qun; Wang, Xin-Nian

    2013-06-28

    We derive a relativistic chiral kinetic equation with manifest Lorentz covariance from Wigner functions of spin-1/2 massless fermions in a constant background electromagnetic field. It contains vorticity terms and a four-dimensional Euclidean Berry monopole which gives an axial anomaly. By integrating out the zeroth component of the 4-momentum p, we reproduce the previous three-dimensional results derived from the Hamiltonian approach, together with the newly derived vorticity terms. The phase space continuity equation has an anomalous source term proportional to the product of electric and magnetic fields (FσρF[over ˜]σρ∼EσBσ). This provides a unified interpretation of the chiral magnetic and vortical effects, chiral anomaly, Berry curvature, and the Berry monopole in the framework of Wigner functions. PMID:23848865

  10. A four dimensional map for escape from resonance: negative energy modes and nonlinear instability

    CERN Document Server

    Martins, Caroline G L; Curry, C

    2016-01-01

    Positive definiteness of a Hamiltonian expanded about an equilibrium point provides only a necessary condition for stability, a criterion known as Dirichlet's theorem. The reason that this criterion is not necessary for stability is because of the possible existence of negative energy modes, which are linearly stable modes of oscillation that have negative energy. When such modes are present, the Hamiltonian is, in general, indefinite. Although such systems with negative energy modes are linearly stable (spectral stable), they are unstable to infinitesimal perturbations under the nonlinear dynamics. In the present work we study this kind of nonlinear instability with the simplest nontrivial four dimensional area-preserving map, which has a cubic degree of freedom, that was designed to mimic the behavior of a Hamiltonian system with one positive and one negative energy mode, and a quadratic degree of freedom, that allows eventual escapes in phase space, usually called as Arnold diffusion.

  11. Comparison of spirometry and abdominal height as four-dimensional computed tomography metrics in lung

    International Nuclear Information System (INIS)

    An important consideration in four-dimensional CT scanning is the selection of a breathing metric for sorting the CT data and modeling internal motion. This study compared two noninvasive breathing metrics, spirometry and abdominal height, against internal air content, used as a surrogate for internal motion. Both metrics were shown to be accurate, but the spirometry showed a stronger and more reproducible relationship than the abdominal height in the lung. The abdominal height was known to be affected by sensor placement and patient positioning while the spirometer exhibited signal drift. By combining these two, a normalization of the drift-free metric to tidal volume may be generated and the overall metric precision may be improved

  12. Assessment of factors connected with radiotherapy influencing the cosmetic effect in breast conserving therapy

    International Nuclear Information System (INIS)

    Aim: To compare cosmetic results of different radiotherapy schedules used in the treatment of breast cancer after breast radiotherapy and to identify factors affecting cosmetic outcomes. Material and methods: Ninety-four patients irradiated. Median follow-up of 29 months (range 18-154 mo.). Patients were treated with standard fractionation 45-50 Gy/20-25 fx/4-5 weeks. Boost up to 10 Gy. Late effects were evaluated using the LENT-SOMA scoring scale. The cosmetic results were assessed on a four-point scale and presence of concomitant chemotherapy. Results: LENT-SOMA grade 3 toxicity was observed only in 8 (8,5%) patients. The factor associated with hyperpigmentation is large breast size. The significant risk factors for teleangiectasia are high dose and use photon energy 1,33 MeV beam. Factors found to impact significantly cosmetics adversely fibrosis was large breast size. Breast fibrosis were more frequent observed in woman after whole dose 50 Gy. There were no differences in breast skin thick between analysed factors. Conclusions: After irradiating large breasts more often than one observes the fibrosis of the breast in the case of small and average breasts and discolour of the skin. Irradiating photons from the cobalt source in the comparison with photons about higher energy at women with large breasts, there is the reason more frequent occurrence of the skin angioma. For the final cosmetic effect of radiotherapy in saving treatment, they do not have the impact: tumor size, boost method, chemical treatment, patients age. (authors)

  13. Four-dimensional computed tomography (4DCT): A review of the current status and applications.

    Science.gov (United States)

    Kwong, Yune; Mel, Alexandra Olimpia; Wheeler, Greg; Troupis, John M

    2015-10-01

    The applications of conventional computed tomography (CT) have been widely researched and implemented in clinical practice. A recent technological innovation in the field of CT is the emergence of four-dimensional computed tomography (4DCT), where a three-dimensional computed tomography volume containing a moving structure is imaged over a period of time, creating a dynamic volume data set. 4DCT has previously been mainly utilised in the setting of radiation therapy planning, but with the development of wide field of view CT, 4DCT has opened major avenues in the diagnostic arena. The aim of this study is to provide a comprehensive narrative review of the literature regarding the current clinical applications of 4DCT. The applications reviewed include both routine diagnostic usage as well as an appraisal of the current research literature. A systematic review of the studies related to 4DCT was conducted. The Medline database was searched using the MeSH subject heading 'Four-Dimensional Computed Tomography'. After excluding non-human and non-English papers, 2598 articles were found. Further exclusion criteria were applied, including date range (since wide field of view CT was introduced in 2007), and exclusion of technical/engineering/physics papers. Further filtration of papers included identification of Review papers. This process yielded 67 papers. Of these, exclusion of papers not specifically discussing 4DCT (cone beam, 4D models) yielded 38 papers. As part of the review, the technique for 4DCT is described, with perspectives as to how it has evolved and its benefits in different clinical indications. PMID:26041442

  14. Quantitation of the reconstruction quality of a four-dimensional computed tomography process for lung cancer patients

    International Nuclear Information System (INIS)

    We have developed a four-dimensional computed tomography (4D CT) technique for mapping breathing motion in radiotherapy treatment planning. A multislice CT scanner (1.5 mm slices) operated in cine mode was used to acquire 12 contiguous slices in each couch position for 15 consecutive scans (0.5 s rotation, 0.25 s between scans) while the patient underwent simultaneous quantitative spirometry measurements to provide a sorting metric. The spirometry-sorted scans were used to reconstruct a 4D data set. A critical factor for 4D CT is quantifying the reconstructed data set quality which we measure by correlating the metric used relative to internal-object motion. For this study, the internal air content within the lung was used as a surrogate for internal motion measurements. Thresholding and image morphological operations were applied to delineate the air-containing tissues (lungs, trachea) from each CT slice. The Hounsfield values were converted to the internal air content (V). The relationship between the air content and spirometer-measured tidal volume (ν) was found to be quite linear throughout the lungs and was used to estimate the overall accuracy and precision of tidal volume-sorted 4D CT. Inspection of the CT-scan air content as a function of tidal volume showed excellent correlations (typically r>0.99) throughout the lung volume. Because of the discovered linear relationship, the ratio of internal air content to tidal volume was indicative of the fraction of air change in each couch position. Theoretically, due to air density differences within the lung and in room, the sum of these ratios would equal 1.11. For 12 patients, the mean value was 1.08±0.06, indicating the high quality of spirometry-based image sorting. The residual of a first-order fit between ν and V was used to estimate the process precision. For all patients, the precision was better than 8%, with a mean value of 5.1%±1.9%. This quantitative analysis highlights the value of using spirometry

  15. Reliability of Quantitative Ultrasonic Assessment of Normal-Tissue Toxicity in Breast Cancer Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: We have recently reported that ultrasound imaging, together with ultrasound tissue characterization (UTC), can provide quantitative assessment of radiation-induced normal-tissue toxicity. This study’s purpose is to evaluate the reliability of our quantitative ultrasound technology in assessing acute and late normal-tissue toxicity in breast cancer radiotherapy. Method and Materials: Our ultrasound technique analyzes radiofrequency echo signals and provides quantitative measures of dermal, hypodermal, and glandular tissue toxicities. To facilitate easy clinical implementation, we further refined this technique by developing a semiautomatic ultrasound-based toxicity assessment tool (UBTAT). Seventy-two ultrasound studies of 26 patients (720 images) were analyzed. Images of 8 patients were evaluated for acute toxicity (<6 months postradiotherapy) and those of 18 patients were evaluated for late toxicity (≥6 months postradiotherapy). All patients were treated according to a standard radiotherapy protocol. To assess intraobserver reliability, one observer analyzed 720 images in UBTAT and then repeated the analysis 3 months later. To assess interobserver reliability, three observers (two radiation oncologists and one ultrasound expert) each analyzed 720 images in UBTAT. An intraclass correlation coefficient (ICC) was used to evaluate intra- and interobserver reliability. Ultrasound assessment and clinical evaluation were also compared. Results: Intraobserver ICC was 0.89 for dermal toxicity, 0.74 for hypodermal toxicity, and 0.96 for glandular tissue toxicity. Interobserver ICC was 0.78 for dermal toxicity, 0.74 for hypodermal toxicity, and 0.94 for glandular tissue toxicity. Statistical analysis found significant changes in dermal (p < 0.0001), hypodermal (p = 0.0027), and glandular tissue (p < 0.0001) assessments in the acute toxicity group. Ultrasound measurements correlated with clinical Radiation Therapy Oncology Group (RTOG) toxicity scores of patients

  16. Assessment of undesirable dose to eye-melanoma patients after proton radiotherapy

    International Nuclear Information System (INIS)

    Radiotherapy with a proton beam of initial energy 55-80 MeV is presently the clinically recommended therapy for some cases of intraocular melanoma such as large melanomas or tumours adjacent to critical organs. Evaluation and optimization of radiation doses outside the treatment volume may contribute to reducing undesirable side-effects and decreasing the risk of occurrence of secondary cancers, particularly for paediatric patients. In this work the undesired doses to organs were assessed basing on Monte Carlo calculation of secondary radiation transport and on results of measurements of neutron and γ-ray doses at the proton therapy facility of the Institute of Nuclear Physics at Krakow. Dosimetry was performed using a He-3-based FHT 762 neutron monitor (Wendi II), a FH40G proportional counter (for γ-rays), and MTS-7 (LiF:Mg,Ti) thermoluminescence detectors (TLDs). Organ doses were calculated in the ADAM anthropomorphic phantom using the MCNPX Monte Carlo transport code and partly verified, for γ-ray doses, with TLD measurements in the RANDO Anderson anthropomorphic phantom. The effective dose due to undesired radiation, including exposure from scattered radiation during the entire process of proton radiotherapy and patient positioning using X-rays, does not exceed 1 mSv.

  17. Four-Dimensional Variational Data Assimilation Experiments for a Heavy Rain Case During the 2002 IOP in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; NI Yunqi

    2005-01-01

    A heavy rainfall event along the mei-yu front during 22-23 June 2002 was chosen for this study. To assess the impact of the routine and additional IOP (intensive observation period) radiosonde observations on the mesoscale heavy rainfall forecast, a series of four-dimensional variational (4DVAR) data assimilation and model simulation experiments was conducted using nonhydrostatic mesoscale model MM5 and the MM5 4DVAR system. The effects of the intensive observations in the different areas on the heavy rainfall forecast were also investigated. The results showed that improvement of the forecast skill for mesoscale heavy rainfall intensity was possible from the assimilation of the IOP radiosonde observations. However,the impact of the IOP observations on the forecast of the rainfall pattern was not significant. Initial conditions obtained through the 4DVAR experiments with a 12-h assimilation window were capable of improving the 24-h forecast. The simulated results after the assimilation showed that it would be best to perform the intensive radiosonde observations in the upstream of the rainfall area and in the moisture passageway area at the same time. Initial conditions created by the 4DVAR led to the low-level moisture convergence over the rainfall area, enhanced frontogenesis and upward motion within the mei-yu front,and intensified middle- and high-level unstable stratification in front of the mei-yu front. Consequently,the heavy rainfall forecast was improved.

  18. Prospective Imaging Assessment of Mortality Risk After Head-and-Neck Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: The optimal roles for imaging-based biomarkers in the management of head-and-neck cancer remain undefined. Unresolved questions include whether functional or anatomic imaging might improve mortality risk assessment for this disease. We addressed these issues in a prospective institutional trial. Methods and Materials: Ninety-eight patients with locally advanced pharyngolaryngeal squamous cell cancer were enrolled. Each underwent pre- and post-chemoradiotherapy contrast-enhanced computed tomography (CT) and 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT imaging. Imaging parameters were correlated with survival outcomes. Results: Low post-radiation primary tumor FDG avidity correlated with improved survival on multivariate analysis; so too did complete primary tumor response by CT alone. Although both imaging modalities lacked sensitivity, each had high specificity and negative predictive value for disease-specific mortality risk assessment. Kaplan-Meier estimates confirmed that both CT and FDG-PET/CT stratify patients into distinct high- and low-probability survivorship groups on the basis of primary tumor response to radiotherapy. Subset analyses demonstrated that the prognostic value for each imaging modality was primarily derived from patients at high risk for local treatment failure (human papillomavirus [HPV]-negative disease, nonoropharyngeal primary disease, or tobacco use). Conclusions: CT alone and FDG-PET/CT are potentially useful tools in head-and-neck cancer-specific mortality risk assessment after radiotherapy, particularly for selective use in cases of high-risk HPV-unrelated disease. Focus should be placed on corroboration and refinement of patient selection for imaging-based biomarkers in future studies.

  19. Performance Evaluation of Automatic Anatomy Segmentation Algorithm on Repeat or Four-Dimensional Computed Tomography Images Using Deformable Image Registration Method

    International Nuclear Information System (INIS)

    Purpose: Auto-propagation of anatomic regions of interest from the planning computed tomography (CT) scan to the daily CT is an essential step in image-guided adaptive radiotherapy. The goal of this study was to quantitatively evaluate the performance of the algorithm in typical clinical applications. Methods and Materials: We had previously adopted an image intensity-based deformable registration algorithm to find the correspondence between two images. In the present study, the regions of interest delineated on the planning CT image were mapped onto daily CT or four-dimensional CT images using the same transformation. Postprocessing methods, such as boundary smoothing and modification, were used to enhance the robustness of the algorithm. Auto-propagated contours for 8 head-and-neck cancer patients with a total of 100 repeat CT scans, 1 prostate patient with 24 repeat CT scans, and 9 lung cancer patients with a total of 90 four-dimensional CT images were evaluated against physician-drawn contours and physician-modified deformed contours using the volume overlap index and mean absolute surface-to-surface distance. Results: The deformed contours were reasonably well matched with the daily anatomy on the repeat CT images. The volume overlap index and mean absolute surface-to-surface distance was 83% and 1.3 mm, respectively, compared with the independently drawn contours. Better agreement (>97% and <0.4 mm) was achieved if the physician was only asked to correct the deformed contours. The algorithm was also robust in the presence of random noise in the image. Conclusion: The deformable algorithm might be an effective method to propagate the planning regions of interest to subsequent CT images of changed anatomy, although a final review by physicians is highly recommended

  20. Quality assessment for VMAT prostate radiotherapy planning based on data envelopment analysis

    International Nuclear Information System (INIS)

    The majority of commercial radiotherapy treatment planning systems requires planners to iteratively adjust the plan parameters in order to find a satisfactory plan. This iterative trial-and-error nature of radiotherapy treatment planning results in an inefficient planning process and in order to reduce such inefficiency, plans can be accepted without achieving the best attainable quality. We propose a quality assessment method based on data envelopment analysis (DEA) to address this inefficiency. This method compares a plan of interest to a set of past delivered plans and searches for evidence of potential further improvement. With the assistance of DEA, planners will be able to make informed decisions on whether further planning is required and ensure that a plan is only accepted when the plan quality is close to the best attainable one. We apply the DEA method to 37 prostate plans using two assessment parameters: rectal generalized equivalent uniform dose (gEUD) as the input and D95 (the minimum dose that is received by 95% volume of a structure) of the planning target volume (PTV) as the output. The percentage volume of rectum overlapping PTV is used to account for anatomical variations between patients and is included in the model as a non-discretionary output variable. Five plans that are considered of lesser quality by DEA are re-optimized with the goal to further improve rectal sparing. After re-optimization, all five plans improve in rectal gEUD without clinically considerable deterioration of the PTV D95 value. For the five re-optimized plans, the rectal gEUD is reduced by an average of 1.84 Gray (Gy) with only an average reduction of 0.07 Gy in PTV D95. The results demonstrate that DEA can correctly identify plans with potential improvements in terms of the chosen input and outputs. (paper)

  1. Quality of life assessment with different radiotherapy schedules in palliative management of advanced carcinoma esophagus: A prospective randomized study

    Directory of Open Access Journals (Sweden)

    Shaveta Mehta

    2008-01-01

    Full Text Available Aim: To investigate the quality of life (QOL of patients with advanced carcinoma esophagus treated with different palliative radiation schedules. Methods: Sixty-two consecutive patients with inoperable, non-metastatic carcinoma of the esophagus were randomly allocated to Arm-A (external radiotherapy 30 Gy/10 fractions + brachytherapy 12 Gy/two sessions, Arm-B (external radiotherapy 30 Gy /10 fractions and Arm-C (external radiotherapy 20Gy /five fractions. The QOL was assessed using the European Organization for Research and Treatment of Cancer questionnaire at presentation, after treatment and at 3 months follow-up. Results: The mean QOL score improved, in arm-A from 38 to 52 after treatment and 56 at 3 months, in arm-B from 30 to 44 after treatment and 55 at 3 months and in arm-C from 24 to 40 after treatment but decreased to 37 at 3 months. Improvement in dysphagia scores at the first follow-up was 46.1% in arm-A, 25.0% in arm-B and 22.6% in arm-C. The difference was maintained at 3 months, with maximum improvement in arm-A (57.6%. No significant differences were found between the three arms with regard to complications and additional procedures needed for relief of dysphagia. Conclusion: In comparison with external radiotherapy alone, external radiotherapy with intraluminal brachytherapy has shown a trend toward better QOL and consistent dysphagia relief without significant difference in adverse effects.

  2. Four-dimensional superquadric-based cardiac phantom for Monte Carlo simulation of radiological imaging systems

    International Nuclear Information System (INIS)

    A four-dimensional (x, y, z, t) composite superquadric-based object model of the human heart for Monte Carlo simulation of radiological imaging systems has been developed. The phantom models the real temporal geometric conditions of a beating heart for frame rates up to 32 per cardiac cycle. Phantom objects are described by boolean combinations of superquadric ellipsoid sections.Moving spherical coordinate systems are chosen to model wall movement whereby points of the ventricle and atria walls are assumed to move towards a moving center-of-gravity point. Due to the non-static coordinate systems, the atrial/ventricular valve plane of the mathematical heart phantom moves up and down along the left ventricular long axis resulting in reciprocal emptying and filling of atria and ventricles. Compared to the base movement, the epicardial apex as well as the superior atria area are almost fixed in space. Since geometric parameters of the objects are directly applied on intersection calculations of the photon ray with object boundaries during Monte Carlo simulation, no phantom discretization artifacts are involved

  3. Five-brane thresholds and membrane instantons in four-dimensional heterotic M-theory

    Energy Technology Data Exchange (ETDEWEB)

    Carlevaro, Luca [Physics Institute, Neuchatel University, A.-L. Breguet 1, CH-2000 Neuchatel (Switzerland)]. E-mail: luca.carlevaro@unine.ch; Derendinger, Jean-Pierre [Physics Institute, Neuchatel University, A.-L. Breguet 1, CH-2000 Neuchatel (Switzerland)]. E-mail: jean-pierre.derendinger@unine.ch

    2006-02-20

    The effective four-dimensional supergravity of M-theory compactified on the orbifold S{sup 1}/Z{sub 2} and a Calabi-Yau threefold includes in general moduli supermultiplets describing massless modes of five-branes. For each brane, one of these fields corresponds to fluctuations along the interval. The five-brane also leads to modifications of the anomaly-cancelling terms in the eleven-dimensional theory, including gauge contributions located on their world-volumes. We obtain the interactions of the brane 'interval modulus' predicted by these five-brane-induced anomaly-cancelling terms and we construct their effective supergravity description. In the condensed phase, these interaction terms generate an effective non-perturbative superpotential which can also be interpreted as instanton effects of open membranes stretching between five-branes and the S{sup 1}/Z{sub 2} fixed hyperplanes. Aspects of the vacuum structure of the effective supergravity are also briefly discussed.

  4. The Estimation of Regional Crop Yield Using Ensemble-Based Four-Dimensional Variational Data Assimilation

    Directory of Open Access Journals (Sweden)

    Zhiwei Jiang

    2014-03-01

    Full Text Available To improve crop model performance for regional crop yield estimates, a new four-dimensional variational algorithm (POD4DVar merging the Monte Carlo and proper orthogonal decomposition techniques was introduced to develop a data assimilation strategy using the Crop Environment Resource Synthesis (CERES-Wheat model. Two winter wheat yield estimation procedures were conducted on a field plot and regional scale to test the feasibility and potential of the POD4DVar-based strategy. Winter wheat yield forecasts for the field plots showed a coefficient of determination (R2 of 0.73, a root mean square error (RMSE of 319 kg/ha, and a relative error (RE of 3.49%. An acceptable yield at the regional scale was estimated with an R2 of 0.997, RMSE of 7346 tons, and RE of 3.81%. The POD4DVar-based strategy was more accurate and efficient than the EnKF-based strategy. In addition to crop yield, other critical crop variables such as the biomass, harvest index, evapotranspiration, and soil organic carbon may also be estimated. The present study thus introduces a promising approach for operationally monitoring regional crop growth and predicting yield. Successful application of this assimilation model at regional scales must focus on uncertainties derived from the crop model, model inputs, data assimilation algorithm, and assimilated observations.

  5. Relativistic positioning: four-dimensional numerical approach in Minkowski space-time

    CERN Document Server

    Puchades, Neus

    2011-01-01

    We simulate the satellite constellations of two Global Navigation Satellite Systems: Galileo (EU) and GPS (USA). Satellite motions in Minkowski space-time are described in an inertial frame with the origin at the center of an idealized spherically symmetric non rotating Earth. The trajectories are then circumferences centered at the same point as Earth. In Minkowski space-time, there is a well known relation (see B. Coll, J. J. Ferrando and J. A. Morales-Lladosa, Class. Quantum Grav., 27, 065013, 2010) between the emission and inertial coordinates of any event. Here, this relation is implemented in a numerical code, which is tested and applied. The first application is a detailed numerical four-dimensional analysis of the so-called emission coordinate region and co-region. In a second application, a GPS (Galileo) satellite is considered as the receiver and its emission coordinates are given by four Galileo (GPS) satellites. The bifurcation problem (double localization) in the positioning of the receiver satel...

  6. A four-dimensional snapshot hyperspectral video-endoscope for bio-imaging applications

    Science.gov (United States)

    Lim, Hoong-Ta; Murukeshan, Vadakke Matham

    2016-04-01

    Hyperspectral imaging has proven significance in bio-imaging applications and it has the ability to capture up to several hundred images of different wavelengths offering relevant spectral signatures. To use hyperspectral imaging for in vivo monitoring and diagnosis of the internal body cavities, a snapshot hyperspectral video-endoscope is required. However, such reported systems provide only about 50 wavelengths. We have developed a four-dimensional snapshot hyperspectral video-endoscope with a spectral range of 400–1000 nm, which can detect 756 wavelengths for imaging, significantly more than such systems. Capturing the three-dimensional datacube sequentially gives the fourth dimension. All these are achieved through a flexible two-dimensional to one-dimensional fiber bundle. The potential of this custom designed and fabricated compact biomedical probe is demonstrated by imaging phantom tissue samples in reflectance and fluorescence imaging modalities. It is envisaged that this novel concept and developed probe will contribute significantly towards diagnostic in vivo biomedical imaging in the near future.

  7. A Four-Dimensional Computed Tomography Analysis of Multiorgan Abdominal Motion

    International Nuclear Information System (INIS)

    Purpose: To characterize and quantify multiorgan respiration-induced motion in the abdomen in liver and pancreatic cancer patients. Methods and Materials: Four-dimensional computed tomography scans were acquired for 18 patients treated for abdominal tumors. Contours of multiple abdominal organs were drawn by the radiation oncologist at one respiratory phase; these contours were propagated to other respiratory phases by deformable registration. Three-dimensional organ models were generated from the resulting contours at each phase. Motions of the bounding box and center of mass were extracted and analyzed for the clinical target volume and organs at risk. Results: On average, the center of mass motion for liver clinical target volumes was 9.7 mm (SD 5 mm) in the superior–inferior direction, with a range of 3 to 18 mm; for pancreatic tumors, the average was 5 mm (SD 1 mm) m with a range of 3 to 7 mm. Abdominal organs move in unison, but with varying amplitudes. Gating near exhale (T40–T60) reduces the range of motion by a factor of ∼10. Conclusion: We have used deformable registration to calculate the trajectories of abdominal organs in four dimensions, based on center of mass and bounding box motion metrics. Our results are compared with previously reported studies. Possible reasons for differences are discussed.

  8. A four-dimensional virtual hand brain–machine interface using active dimension selection

    Science.gov (United States)

    Rouse, Adam G.

    2016-06-01

    Objective. Brain–machine interfaces (BMI) traditionally rely on a fixed, linear transformation from neural signals to an output state-space. In this study, the assumption that a BMI must control a fixed, orthogonal basis set was challenged and a novel active dimension selection (ADS) decoder was explored. Approach. ADS utilizes a two stage decoder by using neural signals to both (i) select an active dimension being controlled and (ii) control the velocity along the selected dimension. ADS decoding was tested in a monkey using 16 single units from premotor and primary motor cortex to successfully control a virtual hand avatar to move to eight different postures. Main results. Following training with the ADS decoder to control 2, 3, and then 4 dimensions, each emulating a grasp shape of the hand, performance reached 93% correct with a bit rate of 2.4 bits s‑1 for eight targets. Selection of eight targets using ADS control was more efficient, as measured by bit rate, than either full four-dimensional control or computer assisted one-dimensional control. Significance. ADS decoding allows a user to quickly and efficiently select different hand postures. This novel decoding scheme represents a potential method to reduce the complexity of high-dimension BMI control of the hand.

  9. Coupling Ensemble Kalman Filter with Four-dimensional Variational Data Assimilation

    Institute of Scientific and Technical Information of China (English)

    Fuqing ZHANG; Meng ZHANG; James A. HANSEN

    2009-01-01

    This study examines the performance of coupling the deterministic four-dimensional variational assimilation system (4DVAR) with an ensemble Kalman filter (EnKF) to produce a superior hybrid approach for data assimilation. The coupled assimilation scheme (E4DVAR) benefits from using the state-dependent uncertainty provided by EnKF while taking advantage of 4DVAR in preventing filter divergence: the 4DVAR analysis produces posterior maximum likelihood solutions through minimization of a cost function about which the ensemble perturbations are transformed, and the resulting ensemble analysis can be propagated forward both for the next assimilation cycle and as a basis for ensemble forecasting. The feasibility and effectiveness of this coupled approach are demonstrated in an idealized model with simulated observations. It is found that the E4DVAR is capable of outperforming both 4DVAR and the EnKF under both perfect-and imperfect-model scenarios. The performance of the coupled scheme is also less sensitive to either the ensemble size or the assimilation window length than those for standard EnKF or 4DVAR implementations.

  10. On the Superstrings-Induced Four-Dimensional Gravity and Its Applications to Cosmology

    Directory of Open Access Journals (Sweden)

    Sergei V. Ketov

    2009-01-01

    Full Text Available We review the status of the fourth-order (quartic in the spacetime curvature terms induced by superstrings/M-theory (compactified on a warped torus in the leading order with respect to the Regge slope parameter, and study their (nonperturbative impact on the evolution of the Hubble scale in the context of the four-dimensional FRW cosmology. After taking into account the quantum ambiguities in the definition of the off-shell superstring effective action, we propose the generalized Friedmann equations, find the existence of their (de Sitter exact inflationary solutions without a spacetime singularity, and constrain the ambiguities by demanding stability and the scale factor duality invariance of our solutions. The most naive (Bel-Robinson tensor squared quartic terms are ruled out, thus giving the evidence for the necessity of extra quartic (Ricci tensor-dependent terms in the off-shell gravitational effective action for superstrings. Our methods are generalizable to the higher orders in the spacetime curvature.

  11. Integrating four-dimensional geographical information and mobile techniques into radiological accident emergency response training

    International Nuclear Information System (INIS)

    When radiological accidents occur, radioactive material may spread into the atmosphere, causing large-scale and long-term contamination. To diminish the effects of such accidents, researchers from many countries have investigated training programs in emergency response to radiological accidents, especially in the wake of several serious radiological accidents. Although many training programs have been proposed, this study identifies two problems: the lack of effective data representation and the lack of complete training records. Therefore, by considering various requirements for relief and evacuation work at radiological accident sites, it integrates four-dimensional geographical information and mobile techniques to construct a training platform for radiological accident emergency response. During training, groups of participants learn to respond to simulated radiological accident scenarios. Moreover, participants can use the training platform to review and discuss training details. Judging by the results, the training platform has not only increased the effectiveness of training programs, but also complied with standard operating procedures for radiological accident emergency response in Taiwan. In conclusion, this study could serve as a useful reference for similar studies and applications. (author)

  12. Simulations of four-dimensional simplicial quantum gravity as dynamical triangulation

    Energy Technology Data Exchange (ETDEWEB)

    Agishtein, M.E.; Migdal, A.A. (Program in Applied and Computational Mathematics, Fine Hall, Princeton Univ., Princeton, NJ (US))

    1992-04-20

    In this paper, Four-Dimensional Simplicial Quantum Gravity is simulated using the dynamical triangulation approach. The authors studied simplicial manifolds of spherical topology and found the critical line for the cosmological constant as a function of the gravitational one, separating the phases of opened and closed Universe. When the bare cosmological constant approaches this line from above, the four-volume grows: the authors reached about 5 {times} 10{sup 4} simplexes, which proved to be sufficient for the statistical limit of infinite volume. However, for the genuine continuum theory of gravity, the parameters of the lattice model should be further adjusted to reach the second order phase transition point, where the correlation length grows to infinity. The authors varied the gravitational constant, and they found the first order phase transition, similar to the one found in three-dimensional model, except in 4D the fluctuations are rather large at the transition point, so that this is close to the second order phase transition. The average curvature in cutoff units is large and positive in one phase (gravity), and small negative in another (antigravity). The authors studied the fractal geometry of both phases, using the heavy particle propagator to define the geodesic map, as well as with the old approach using the shortest lattice paths.

  13. Simulations of four-dimensional simplicial quantum gravity as dynamical triangulation

    International Nuclear Information System (INIS)

    In this paper, Four-Dimensional Simplicial Quantum Gravity is simulated using the dynamical triangulation approach. The authors studied simplicial manifolds of spherical topology and found the critical line for the cosmological constant as a function of the gravitational one, separating the phases of opened and closed Universe. When the bare cosmological constant approaches this line from above, the four-volume grows: the authors reached about 5 x 104 simplexes, which proved to be sufficient for the statistical limit of infinite volume. However, for the genuine continuum theory of gravity, the parameters of the lattice model should be further adjusted to reach the second order phase transition point, where the correlation length grows to infinity. The authors varied the gravitational constant, and they found the first order phase transition, similar to the one found in three-dimensional model, except in 4D the fluctuations are rather large at the transition point, so that this is close to the second order phase transition. The average curvature in cutoff units is large and positive in one phase (gravity), and small negative in another (antigravity). The authors studied the fractal geometry of both phases, using the heavy particle propagator to define the geodesic map, as well as with the old approach using the shortest lattice paths

  14. Combining four dimensional variational data assimilation and particle filtering for estimating volcanic ash emissions

    Science.gov (United States)

    Franke, Philipp; Elbern, Hendrik

    2016-04-01

    Estimating volcanic ash emissions is a very challenging task due to limited monitoring capacities of the ash plume and nonlinear processes in the atmosphere, which renders application of source strength and injection height estimations difficult. Most models, which estimate volcanic ash emissions, make strong simplifications of the dispersion of volcanic ash and corresponding atmospheric processes. The objective of this work is to estimate volcanic ash emissions and simulate the ensuing dispersion applying a full chemistry transport model in a hybrid approach by using its adjoint as well as an ensemble of model runs to quantify forecast uncertainties. Therefore, the four dimensional variational data assimilation version of the EURAD-IM chemistry transport model is extended to include a Sequential Importance Resampling Smoother (SIRS), introducing novel weighting and resampling strategies. In the main SIRS step the ensemble members exchange high rated emission patterns while rejecting emission patterns with low value for the forecast. The emission profiles of the ensemble members are perturbed afterwards to guarantee different emissions for all ensemble members. First identical twin experiments show the ability of the system to estimate the temporal and vertical distribution of volcanic ash emissions. The 4D-var data assimilation algorithm of the new system additionally provides quantitative emission estimation.

  15. Two-dimensional topological field theories coupled to four-dimensional BF theory

    International Nuclear Information System (INIS)

    Four-dimensional BF theory admits a natural coupling to extended sources supported on two-dimensional surfaces or string world sheets. Solutions of the theory are in one to one correspondence with solutions of Einstein equations with distributional matter (cosmic strings). We study new (topological field) theories that can be constructed by adding extra degrees of freedom to the two-dimensional world sheet. We show how two-dimensional Yang-Mills degrees of freedom can be added on the world sheet, producing in this way, an interactive (topological) theory of Yang-Mills fields with BF fields in four dimensions. We also show how a world sheet tetrad can be naturally added. As in the previous case the set of solutions of these theories are contained in the set of solutions of Einstein's equations if one allows distributional matter supported on two-dimensional surfaces. These theories are argued to be exactly quantizable. In the context of quantum gravity, one important motivation to study these models is to explore the possibility of constructing a background-independent quantum field theory where local degrees of freedom at low energies arise from global topological (world sheet) degrees of freedom at the fundamental level

  16. Four-dimensional formulation of the sector-improved residue subtraction scheme

    International Nuclear Information System (INIS)

    Four years ago, one of us introduced a novel subtraction scheme [1] for the evaluation of double-real radiation contributions to cross sections at next-to-next-to-leading order (NNLO) in QCD. This approach, named SecToR Improved Phase sPacE for Real radiation (STRIPPER), has already found several non-trivial applications. In particular, it has allowed for the determination of NNLO corrections to hadronic top-quark pair production, fully differential top-quark decays, inclusive semileptonic charmless b-quark decays, associated Higgs boson and jet production in gluon fusion, muon decay spin asymmetry, and t-channel single-top production. Common to these calculations was the use of conventional dimensional regularization (CDR). In this publication, we present a complete formulation of the subtraction scheme for arbitrary processes with any number of colored partons in the final state, and up to two partons in the initial state. Furthermore, we modify the integrated subtraction terms of the double-real radiation to enable the introduction of the 't Hooft–Veltman version of dimensional regularization (HV), in which resolved states are four-dimensional. We demonstrate the correctness of our approach on the example of top-quark pair production in the gluon fusion channel

  17. Four-dimensional dielectric property image obtained from electron spectroscopic imaging series.

    Science.gov (United States)

    Lo, S C; Kai, J J; Chen, F R; Chang, L; Chen, L C; Chiang, C C; Ding, P; Chin, B; Zhang, H; Chen, F

    2001-01-01

    We have demonstrated a new quantitative method to characterize two-dimensional distributions of energy-dependent dielectric function of materials from low loss electron spectroscopic image (ESI) series. Two problems associated with extracted image-spectrum from the low-loss image series, under-sampling and loss of energy resolution, were overcome by using fast Fourier transformation (FFT) interpolation and maximum entropy deconvolution method. In this study, Black Diamond/Si3N4/SiO2/Si-substrate dielectric layer designed for copper metallization was used as the sample. We show that the reconstructed (FFT interpolated and maximum entropy deconvoluted) image-spectrum obtained from ESI series images can be quantified with the same accuracy as conventional electron energy-loss spectroscopy spectra. Since the analysis of the dielectric function is sensitive to the local thickness of the specimen using Kramers-Kronig analysis, we also developed a new method to quantitatively determine the dielectric constant for low-k materials. We have determined the thickness of the Black Diamond using the extrapolated thickness method from the materials of known dielectric constants. Using Kramers-Kronig formula, the dielectric function map can be deduced from two-dimensional reconstructed single scattering spectra with providing the information of thickness. We proposed a four-dimensional data presentation for revealing the uniformity of the energy dependent property. The accuracy of our methods depends on the thickness determination and on the quality of the reconstructed spectra from the image series. PMID:11918416

  18. Four-dimensional computed tomography (4D CT). Concepts and preliminary development

    International Nuclear Information System (INIS)

    Four-dimensional computed tomography (4D CT) is a dynamic volume imaging system of moving organs with an image quality comparable to that of conventional CT. 4D CT will be realized by several technical breakthroughs for dynamic cone-beam CT: a large-area two-dimensional (2D) detector; high-speed data transfer system; reconstruction algorithms; ultra-high-speed reconstruction computer; and high-speed, continuously rotating gantry. Among these, development of the 2D detector is one of the main tasks because it should have as wide a dynamic range and as high a data acquisition speed (view rate) as present CT detectors. We are now developing a 4D CT scanner together with the key components. It will take one volume image in 0.5 sec with a 3D matrix of 512 x 512 x 512. This paper describes the concepts and designs of the 4D CT system, as well as preliminary development of the 2D detector. (author)

  19. Chiral Four-Dimensional F-Theory Compactifications With SU(5) and Multiple U(1)-Factors

    CERN Document Server

    Cvetič, Mirjam; Klevers, Denis; Piragua, Hernan

    2013-01-01

    We develop geometric techniques to determine the spectrum and the chiral indices of matter multiplets for four-dimensional F-theory compactifications on elliptic Calabi-Yau fourfolds with rank two Mordell-Weil group. The general elliptic fiber is the Calabi-Yau onefold in dP_2. We classify its resolved elliptic fibrations over a general base B. The study of singularities of these fibrations leads to explicit matter representations, that we determine both for U(1)xU(1) and SU(5)xU(1)xU(1) constructions. We determine for the first time certain matter curves and surfaces using techniques involving prime ideals. The vertical cohomology ring of these fourfolds is calculated for both cases and general formulas for the Euler numbers are derived. Explicit calculations are presented for a specific base B=P^3. We determine the general G_4-flux that belongs to H^{(2,2)}_V of the resolved Calabi-Yau fourfolds. As a by-product, we derive for the first time all conditions on G_4-flux in general F-theory compactifications w...

  20. Monocosm a linear solution to the effective four-dimensionality problem

    CERN Document Server

    Trifonov, V Yu

    1995-01-01

    In this note we formalize certain aspects of measurement \\textit{(active observation)} process which makes it possible to express in strict terms the concept of rational behaviour and degree to which logic of the observer determines what he perceives. This leads to a first-order theory shown to possess a real-world model: if a resercher's logic is Boolean, he is bound to perceive his spacetime as a four-dimensional pseudo-Riemannian manifold of signature 2, with a big-bang geometry. These connections between the type of an observer's logic and large-scale structure of the observable universe generate a testable effect similar to the action of a positive cosmological constant, imply Haar integration-over-spacetime and also provide a heuristic limit on the number of matter generations. The result casts some doubts (arising also from the necessity of renormalization procedures and other difficulties of Gauge-Grassmannian schemes) that \\textit{classical} mathematics (i.e. the mathematics of the topos of sets) is ...

  1. Four-Dimensional Coded Modulation with Bit-wise Decoders for Future Optical Communications

    CERN Document Server

    Alvarado, Alex

    2014-01-01

    Coded modulation (CM) is the combination of forward error correction (FEC) and multilevel constellations. Coherent optical communication systems result in a four-dimensional (4D) signal space, which naturally leads to 4D-CM transceivers. A practically attractive design paradigm is to use a bit-wise decoder, where the detection process is (suboptimally) separated into two steps: soft-decision demapping followed by binary decoding. In this paper, bit-wise decoders are studied from an information-theoretic viewpoint. 4D constellations with up to 4096 constellation points are considered. Metrics to predict the post-FEC bit-error rate (BER) of bit-wise decoders are analyzed. The mutual information is shown to fail at predicting the post-FEC BER of bit-wise decoders and the so-called generalized mutual information is shown to be a much more robust metric. It is also shown that constellations that transmit and receive information in each polarization and quadrature independently (e.g., PM-QPSK, PM-16QAM, and PM-64QA...

  2. Neuropsychological assessment before and after radiotherapy in a child with an intracranial tumor: case report

    Directory of Open Access Journals (Sweden)

    Alessandra Pereira Lopes

    2013-12-01

    Full Text Available INTRODUCTION: Brain tumors are the most common solid tumors and the second largest group of neoplasms diagnosed in childhood. Treatment includes surgery, radiotherapy, and chemotherapy. However, radiotherapy can cause complications, e.g., cognitive deficits. CASE DESCRIPTION: We describe the case of a child diagnosed with a brain tumor evaluated before and after radiotherapy to investigate cognitive decline after treatment. The results showed a decline in Intelligence Quotient (IQ scores and reversal of the predominance of verbal and nonverbal skills. After radiotherapy, the subject showed slowness, academic deficits, and difficulties learning new information. COMMENTS: Even though the post-treatment evaluation showed scores compatible with the average, comparison between pre- and post-treatment evaluations demonstrated the impact of radiotherapy on the subject's cognitive profile. These results highlight the importance of evaluating patients who undergo radiotherapy before and after treatment and understanding neuropsychological scores associated with the subjects' complaints.

  3. Generating one-, two-, three- and four-scroll attractors from a novel four-dimensional smooth autonomous chaotic system

    International Nuclear Information System (INIS)

    A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper, which can exhibit periodic orbit and chaos under the conditions on the system parameters. Importantly, the system can generate one-, two-, three- and four-scroll chaotic attractors with appropriate choices of parameters. Interestingly, all the attractors are generated only by changing a single parameter. The dynamic analysis approach in the paper involves time series, phase portraits, Poincaré maps, a bifurcation diagram, and Lyapunov exponents, to investigate some basic dynamical behaviours of the proposed four-dimensional system. (general)

  4. Randomized Clinical Trial to Assess the Efficacy of Radiotherapy in Primary Mediastinal Large B-Lymphoma

    International Nuclear Information System (INIS)

    Purpose: We developed a controlled clinical trial to assess the efficacy and toxicity of adjuvant-involved field radiotherapy (IFRT) in patients with primary mediastinal B-cell lymphoma that achieved complete response after the patients were treated with cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab (R-CHOP-14). Methods and Materials: Between January 2001 and June 2004, 124 consecutive patients who were in complete remission after dose dense chemotherapy and rituximab administration (R-CHOP14) were randomly assigned to received IFRT (30 Gy). Sixty-three patients received IFR, and 61 patients did not (control group). Results: The study aimed to include 182 patients in each arm but was closed prematurely because in a security analysis (June 2004), progression and early relapse were more frequent in patients that did not received IFRT. Patients were followed until March 2009, at which point actuarial curves at 10 years showed that progression free-survival was 72% in patients who received IFR and 20% in the control group (p < 0.001), overall survival was 72% and 31%, respectively (p < 0.001). Acute toxicity was mild and well tolerated. Discussion: Adjuvant radiotherapy to sites of bulky disease was the only difference to have an improvement in outcome in our patients; the use of rituximab during induction did not improve complete response rates and did affect overall survival; patients who received rituximab but not IFRT had a worse prognosis. Conclusions: The use of IFRT in patients with primary mediastinal B-cell lymphoma who achieved complete response remain as the best treatment available, even in patients that received rituximab during induction.

  5. Randomized Clinical Trial to Assess the Efficacy of Radiotherapy in Primary Mediastinal Large B-Lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Aviles, Agustin, E-mail: agustin.aviles@imss.gob.mx [Oncology Research Unit, Oncology Hospital, National Medical Center, IMSS, Mexico, D. F. (Mexico); Neri, Natividad [Department of Hematology, Oncology Hospital, National Medical Center, IMSS, Mexico, D. F. (Mexico); Fernandez, Raul [Department of Radiation Therapy, Oncology Hospital, National Medical Center, IMSS, Mexico, D. F. (Mexico); Huerta-Guzman, Judith; Nambo, Maria J. [Department of Hematology, Oncology Hospital, National Medical Center, IMSS, Mexico, D. F. (Mexico)

    2012-07-15

    Purpose: We developed a controlled clinical trial to assess the efficacy and toxicity of adjuvant-involved field radiotherapy (IFRT) in patients with primary mediastinal B-cell lymphoma that achieved complete response after the patients were treated with cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab (R-CHOP-14). Methods and Materials: Between January 2001 and June 2004, 124 consecutive patients who were in complete remission after dose dense chemotherapy and rituximab administration (R-CHOP14) were randomly assigned to received IFRT (30 Gy). Sixty-three patients received IFR, and 61 patients did not (control group). Results: The study aimed to include 182 patients in each arm but was closed prematurely because in a security analysis (June 2004), progression and early relapse were more frequent in patients that did not received IFRT. Patients were followed until March 2009, at which point actuarial curves at 10 years showed that progression free-survival was 72% in patients who received IFR and 20% in the control group (p < 0.001), overall survival was 72% and 31%, respectively (p < 0.001). Acute toxicity was mild and well tolerated. Discussion: Adjuvant radiotherapy to sites of bulky disease was the only difference to have an improvement in outcome in our patients; the use of rituximab during induction did not improve complete response rates and did affect overall survival; patients who received rituximab but not IFRT had a worse prognosis. Conclusions: The use of IFRT in patients with primary mediastinal B-cell lymphoma who achieved complete response remain as the best treatment available, even in patients that received rituximab during induction.

  6. Development of educational programs using Dagik Earth, a four dimensional display of the Earth and planets

    Science.gov (United States)

    Saito, A.; Akiya, Y.; Yoshida, D.; Odagi, Y.; Yoshikawa, M.; Tsugawa, T.; Takahashi, M.; Kumano, Y.; Iwasaki, S.

    2010-12-01

    We have developed a four-dimensional display system of the Earth and planets to use in schools, science centers, and research institutes. It can display the Earth and planets in three-dimensional way without glasses, and the time variation of the scientific data can be displayed on the Earth and planets image. The system is named Dagik Earth, and educational programs using Dagik Earth have been developed for schools and science centers. Three dimensional displays can show the Earth and planets in exact form without any distortion, which cannot be achieved with two-dimensional display. Furthermore it can provide a sense of reality. There are several systems for the three-dimensional presentation of the Earth, such as Science on a sphere by NOAA, and Geocosmos by Miraikan, Japan. Comparing these systems, the advantage of Dagik Earth is portability and affordability. The system uses ordinary PC and PC projector. Only a spherical screen is the special equipment of Dagik Earth. Therefore Dagik Earth is easy to use in classrooms. Several educational programs have been developed and carried out in high schools, junior high schools, elementary schools and science centers. Several research institutes have used Dagik Earth in their public outreach programs to demonstrate their novel scientific results to public in an attractive way of presentation. A community of users and developers of Dagik Earth is being formed in Japan. In the presentation, the outline of Dagik Earth and the educational programs using Dagik Earth will be presented. Its future plan will also be discussed.

  7. The analysis of thoracic esophageal tumor mobility during normal respiration with four-dimensional computed tomography

    International Nuclear Information System (INIS)

    Objective: To investigate the motion characteristics of primary thoracic esophageal carcinoma with four-dimensional computed tomography (4DCT). Methods: Sixteen patients with primary thoracic esophageal carcinoma received respiratory gated 4DCT imaging,mapping the GTV1-GTV10 on every patient's each subsequent CT image of 10 images in the full-respiratory phase, and measuring the displacement of each centre of GTV. These displacements and directions were analyzed on different segments of esophagus. Results: The mean total lung volume and GTV volume was 2993.5 cm3, 35.00 cm3 and 3362.12 cm3, 34.84 cm3 respectively on end-expiration and end-inspiration phases (t=12.36, P=0.000 and t=-0.61, P=0.546). The total mean peak to peak displacement of GTV were 0.65 mm, 0.55 mm, and 2.03 mm in x, y- and z-axis direction,respectively (F=41.14, P=0.000). The motion in x-axis,y-axis and z-axis were 0.50 mm, 0.48 mm, 1.23 mm in the upper segment (F=5.45, P=0.017), 0.68 mm, 0.62 mm, 1.97 mm in the middle segment (F=27.74, P=0.000), 0.72 mm, 0.38 mm, 3.05 mm in the lower segment, respectively (F=15.61, P=0.000). Conclusions: The displacement of tumor in z axis is more notable than x-, y-axis in thoracic esophageal carcinoma. The displacement of tumor x-, y- and z-axis is different in different segment of thoracic esophageal carcinoma. (authors)

  8. Complete classification of parallel Lorentz surfaces in four-dimensional neutral pseudosphere

    Science.gov (United States)

    Chen, Bang-Yen

    2010-08-01

    A Lorentz surface of an indefinite space form is called parallel if its second fundamental form is parallel with respect to the Van der Waerden-Bortolotti connection. Such surfaces are locally invariant under the reflection with respect to the normal space at each point. Parallel surfaces are important in geometry as well as in general relativity since extrinsic invariants of such surfaces do not change from point to point. Parallel Lorentz surfaces in four-dimensional (4D) Lorentzian space forms are classified by Chen and Van der Veken ["Complete classification of parallel surfaces in 4-dimensional Lorentz space forms," Tohoku Math. J. 61, 1 (2009)]. Recently, explicit classification of parallel Lorentz surfaces in the pseudo-Euclidean 4-space E24 and in the pseudohyperbolic 4-space H24(-1) are obtained recently by Chen et al. ["Complete classification of parallel Lorentzian surfaces in Lorentzian complex space forms," Int. J. Math. 21, 665 (2010); "Complete classification of parallel Lorentz surfaces in neutral pseudo hyperbolic 4-space," Cent. Eur. J. Math. 8, 706 (2010)], respectively. In this article, we completely classify the remaining case; namely, parallel Lorentz surfaces in 4D neutral pseudosphere S24(1). Our result states that there are 24 families of such surfaces in S24(1). Conversely, every parallel Lorentz surface in S24(1) is obtained from one of the 24 families. The main result indicates that there are major differences between Lorentz surfaces in the de Sitter 4-space dS4 and in the neutral pseudo 4-sphere S24.

  9. Complete classification of parallel Lorentz surfaces in four-dimensional neutral pseudosphere

    International Nuclear Information System (INIS)

    A Lorentz surface of an indefinite space form is called parallel if its second fundamental form is parallel with respect to the Van der Waerden-Bortolotti connection. Such surfaces are locally invariant under the reflection with respect to the normal space at each point. Parallel surfaces are important in geometry as well as in general relativity since extrinsic invariants of such surfaces do not change from point to point. Parallel Lorentz surfaces in four-dimensional (4D) Lorentzian space forms are classified by Chen and Van der Veken [''Complete classification of parallel surfaces in 4-dimensional Lorentz space forms,'' Tohoku Math. J. 61, 1 (2009)]. Recently, explicit classification of parallel Lorentz surfaces in the pseudo-Euclidean 4-space E24 and in the pseudohyperbolic 4-space H24(-1) are obtained recently by Chen et al. [''Complete classification of parallel Lorentzian surfaces in Lorentzian complex space forms,'' Int. J. Math. 21, 665 (2010); ''Complete classification of parallel Lorentz surfaces in neutral pseudo hyperbolic 4-space,'' Cent. Eur. J. Math. 8, 706 (2010)], respectively. In this article, we completely classify the remaining case; namely, parallel Lorentz surfaces in 4D neutral pseudosphere S24(1). Our result states that there are 24 families of such surfaces in S24(1). Conversely, every parallel Lorentz surface in S24(1) is obtained from one of the 24 families. The main result indicates that there are major differences between Lorentz surfaces in the de Sitter 4-space dS4 and in the neutral pseudo 4-sphere S24.

  10. Robust principal component analysis-based four-dimensional computed tomography

    Science.gov (United States)

    Gao, Hao; Cai, Jian-Feng; Shen, Zuowei; Zhao, Hongkai

    2011-06-01

    The purpose of this paper for four-dimensional (4D) computed tomography (CT) is threefold. (1) A new spatiotemporal model is presented from the matrix perspective with the row dimension in space and the column dimension in time, namely the robust PCA (principal component analysis)-based 4D CT model. That is, instead of viewing the 4D object as a temporal collection of three-dimensional (3D) images and looking for local coherence in time or space independently, we perceive it as a mixture of low-rank matrix and sparse matrix to explore the maximum temporal coherence of the spatial structure among phases. Here the low-rank matrix corresponds to the 'background' or reference state, which is stationary over time or similar in structure; the sparse matrix stands for the 'motion' or time-varying component, e.g., heart motion in cardiac imaging, which is often either approximately sparse itself or can be sparsified in the proper basis. Besides 4D CT, this robust PCA-based 4D CT model should be applicable in other imaging problems for motion reduction or/and change detection with the least amount of data, such as multi-energy CT, cardiac MRI, and hyperspectral imaging. (2) A dynamic strategy for data acquisition, i.e. a temporally spiral scheme, is proposed that can potentially maintain similar reconstruction accuracy with far fewer projections of the data. The key point of this dynamic scheme is to reduce the total number of measurements, and hence the radiation dose, by acquiring complementary data in different phases while reducing redundant measurements of the common background structure. (3) An accurate, efficient, yet simple-to-implement algorithm based on the split Bregman method is developed for solving the model problem with sparse representation in tight frames.

  11. Mesoscale modeling and four-dimensional data assimilation in areas of highly complex terrain

    International Nuclear Information System (INIS)

    A multiscale four-dimensional data assimilation (FDDA) technique, based on Newtonian relaxation, is incorporated into a mesoscale model and evaluated using meteorological and tracer data collected during a field experiment. The mesoscale model is used to predict synoptically driven flows and small-scale circulations influenced by terrain near the Rocky Flats Plant (RFP) for four nocturnal periods. Data assimilation is used to create dynamically consistent analysis fields based on mesoscale forecasts and asynoptic data. Observations from towers, minisodars, airsondes, tethersondes, rawinsondes, and profilers near RFP, as well as observations from surface stations throughout Colorado, are incorporated into the high-resolution analysis fields. Wind and turbulence quantities produced by the mesoscale model are used to determine the dispersion of tracer released from RFP for each evening. A subjective and statistical evaluation of meteorological and dispersion results is performed to examine FDDA effects on nocturnal circulations and tracer transport. The mesoscale model is able to qualitatively predict the mesobeta-scale drainage flows; however, the largest wind forecast errors occurred in a region immediately adjacent to the foothills. The FDDA technique reduced overall errors in the atmospheric and dispersion calculations, while the model generated realistic small-scale circulations not resolved by the data. Still, the model did not capture the shallow surface drainage flows east of RFP for two evenings during the field experiment. When the model was initialized with high-resolution analysis fields generated by FDDA and left to forecast, little improvement in forecasts were seen two hours after initialization time. This may be due to the fact that only observed horizontal wind components were assimilated into the analyses generated by FDDA; assimilation of temperature observations was not included. 32 refs., 12 figs., 4 tabs

  12. Impact of four-dimensional data assimilation (FDDA) on urban climate analysis

    Science.gov (United States)

    Pan, Linlin; Liu, Yubao; Liu, Yuewei; Li, Lei; Jiang, Yin; Cheng, Will; Roux, Gregory

    2015-12-01

    This study investigates the impact of four-dimensional data assimilation (FDDA) on urban climate analysis, which employs the NCAR (National Center for Atmospheric Research) WRF (the weather research and forecasting model) based on climate FDDA (CFDDA) technology to develop an urban-scale microclimatology database for the Shenzhen area, a rapidly developing metropolitan located along the southern coast of China, where uniquely high-density observations, including ultrahigh-resolution surface AWS (automatic weather station) network, radio sounding, wind profilers, radiometers, and other weather observation platforms, have been installed. CFDDA is an innovative dynamical downscaling regional climate analysis system that assimilates diverse regional observations; and has been employed to produce a 5 year multiscale high-resolution microclimate analysis by assimilating high-density observations at Shenzhen area. The CFDDA system was configured with four nested-grid domains at grid sizes of 27, 9, 3, and 1 km, respectively. This research evaluates the impact of assimilating high-resolution observation data on reproducing the refining features of urban-scale circulations. Two experiments were conducted with a 5 year run using CFSR (climate forecast system reanalysis) as boundary and initial conditions: one with CFDDA and the other without. The comparisons of these two experiments with observations indicate that CFDDA greatly reduces the model analysis error and is able to realistically analyze the microscale features such as urban-rural-coastal circulation, land/sea breezes, and local-hilly terrain thermal circulations. It is demonstrated that the urbanization can produce 2.5 k differences in 2 m temperatures, delays/speeds up the land/sea breeze development, and interacts with local mountain-valley circulations.

  13. Four-dimensional CT in the study of lung volume and respiratory movement

    International Nuclear Information System (INIS)

    Objective: To evaluate the respiratory movement of the both lungs with four-dimensional CT(4DCT), and determine the optimal respiratory phase series CT images for radiation dose calculation. Methods: From November 2005 to November 2006, thirty patients with lung cancer who received 4DCT scan were enrolled, including 15 left and 15 right lung cancer cases, 25 men and 5 women. The media age was 55 (35-78) years old. After 4DCT scanning, the image was treated with Advantage 4D workstation, and then transmitted into Pinnacle station (Adac 7.4). The both lungs were automatically outlined using Pinnacle station with CT recognition value of -900 to -200 Hu. Then the same physician examined the unreasonable parts and revised them. After the delineation was completed, the volume of 10 respiratory phases of lung was obtained. Results: The average respiratory phase in inspiratory and expiratory phases was 78.87% ± 2.71% and 26.32% ± 3.17% in the tumor located lung, 77.55% ± 2.81% and 24.73% ± 2.55% in the healthy lung. The maximum and minimum mean volume was 106.48% ± 3.00% and 94.23% ± 2.78% in the tumor located lung,107.47% ± 2.43% and 93.65% ± 2.32% in the healthy lung. The volume at the end of inspiratory and expiratory was 106.43% ± 3.07% and 94.63% ± 2.71% in the tumor located lung, 107.37% ± 4.62% and 93.98% ± 2.34% in the healthy lung. Conclusions: The series CT images scan on 20%, 30% and 80% respiratory phases are reasonable for radiation dose calculation. The maximum and minimum average lung volumes are almost equal to those at the end of inspiratory and expiratory. (authors)

  14. Robust principal component analysis-based four-dimensional computed tomography

    International Nuclear Information System (INIS)

    The purpose of this paper for four-dimensional (4D) computed tomography (CT) is threefold. (1) A new spatiotemporal model is presented from the matrix perspective with the row dimension in space and the column dimension in time, namely the robust PCA (principal component analysis)-based 4D CT model. That is, instead of viewing the 4D object as a temporal collection of three-dimensional (3D) images and looking for local coherence in time or space independently, we perceive it as a mixture of low-rank matrix and sparse matrix to explore the maximum temporal coherence of the spatial structure among phases. Here the low-rank matrix corresponds to the 'background' or reference state, which is stationary over time or similar in structure; the sparse matrix stands for the 'motion' or time-varying component, e.g., heart motion in cardiac imaging, which is often either approximately sparse itself or can be sparsified in the proper basis. Besides 4D CT, this robust PCA-based 4D CT model should be applicable in other imaging problems for motion reduction or/and change detection with the least amount of data, such as multi-energy CT, cardiac MRI, and hyperspectral imaging. (2) A dynamic strategy for data acquisition, i.e. a temporally spiral scheme, is proposed that can potentially maintain similar reconstruction accuracy with far fewer projections of the data. The key point of this dynamic scheme is to reduce the total number of measurements, and hence the radiation dose, by acquiring complementary data in different phases while reducing redundant measurements of the common background structure. (3) An accurate, efficient, yet simple-to-implement algorithm based on the split Bregman method is developed for solving the model problem with sparse representation in tight frames.

  15. Chiral four-dimensional F-theory compactifications with SU(5) and multiple U(1)-factors

    Science.gov (United States)

    Cvetič, Mirjam; Grassi, Antonella; Klevers, Denis; Piragua, Hernan

    2014-04-01

    We develop geometric techniques to determine the spectrum and the chiral indices of matter multiplets for four-dimensional F-theory compactifications on elliptic Calabi-Yau fourfolds with rank two Mordell-Weil group. The general elliptic fiber is the Calabi-Yau onefold in dP 2. We classify its resolved elliptic fibrations over a general base B. The study of singularities of these fibrations leads to explicit matter representations, that we determine both for U(1) × U(1) and SU(5) × U(1) × U(1) constructions. We determine for the first time certain matter curves and surfaces using techniques involving prime ideals. The vertical cohomology ring of these fourfolds is calculated for both cases and general formulas for the Euler numbers are derived. Explicit calculations are presented for a specific base B = ℙ3. We determine the general G 4-flux that belongs to of the resolved Calabi-Yau fourfolds. As a by-product, we derive for the first time all conditions on G 4-flux in general F-theory compactifications with a non-holomorphic zero section. These conditions have to be formulated after a circle reduction in terms of Chern-Simons terms on the 3D Coulomb branch and invoke M-theory/F-theory duality. New Chern-Simons terms are generated by Kaluza-Klein states of the circle compactification. We explicitly perform the relevant field theory computations, that yield non-vanishing results precisely for fourfolds with a non-holomorphic zero section. Taking into account the new Chern-Simons terms, all 4D matter chiralities are determined via 3D M-theory/F-theory duality. We independently check these chiralities using the subset of matter surfaces we determined. The presented techniques are general and do not rely on toric data.

  16. A New Global Four-Dimensional Variational Ocean Data Assimilation System and Its Application

    Institute of Scientific and Technical Information of China (English)

    LIU Juan; WANG Bin; LIU Hailong; YU Yongqiang

    2008-01-01

    A four-dimensional variational data assimilation (4DVar) system of the LASG/IAP Climate Ocean Model, version 1.0 (LICOM1.0), named LICOM-3DVM, has been developed using the three-dimensional variational data assimilation of mapped observation (3DVM), a 4DVar method newly proposed in the past two years. Two experiments with 12-year model integrations were designed to validate it. One is the as- similation run, called ASSM, which incorporated the analyzed weekly sea surface temperature (SST) fields from Reynolds and Smith (OISST) between 1990 and 2001 once a week by the LICOM-3DVM. The other is the control run without any assimilation, named CTL. ASSM shows that the simulated temperatures of the upper ocean (above 50 meters), especially the SST of equatorial Pacific, coincide with the Tropic Atmo- sphere Ocean (TAO) mooring data, the World Ocean Atlas 2001 (WOA01) data and the Met Office Hadley Centre's sea ice and sea surface temperature (HadISST) data. It decreased the cold bias existing in CTL in the eastern Pacific and produced a Nino index that agrees with observation well. The validation results suggest that the LICOM-3DVM is able to effectively adjust the model results of the ocean temperature, although it's hard to correct the subsurface results and it even makes them worse in some areas due to the incorporation of only surface data. Future development of the LICOM-3DVM is to include subsurface in situ observations and satellite observations to further improve model simulations.

  17. TH-A-19A-10: Fast Four Dimensional Monte Carlo Dose Computations for Proton Therapy of Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: To develop and validate a fast and accurate four dimensional (4D) Monte Carlo (MC) dose computation system for proton therapy of lung cancer and other thoracic and abdominal malignancies in which the delivered dose distributions can be affected by respiratory motion of the patient. Methods: A 4D computer tomography (CT) scan for a lung cancer patient treated with protons in our clinic was used to create a time dependent patient model using our in-house, MCNPX-based Monte Carlo system (“MC2”). The beam line configurations for two passively scattered proton beams used in the actual treatment were extracted from the clinical treatment plan and a set of input files was created automatically using MC2. A full MC simulation of the beam line was computed using MCNPX and a set of phase space files for each beam was collected at the distal surface of the range compensator. The particles from these phase space files were transported through the 10 voxelized patient models corresponding to the 10 phases of the breathing cycle in the 4DCT, using MCNPX and an accelerated (fast) MC code called “FDC”, developed by us and which is based on the track repeating algorithm. The accuracy of the fast algorithm was assessed by comparing the two time dependent dose distributions. Results: The error of less than 1% in 100% of the voxels in all phases of the breathing cycle was achieved using this method with a speedup of more than 1000 times. Conclusion: The proposed method, which uses full MC to simulate the beam line and the accelerated MC code FDC for the time consuming particle transport inside the complex, time dependent, geometry of the patient shows excellent accuracy together with an extraordinary speed

  18. TH-A-19A-10: Fast Four Dimensional Monte Carlo Dose Computations for Proton Therapy of Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Mirkovic, D; Titt, U; Mohan, R [U.T M.D. Anderson Cancer Center, Houston, TX (United States); Yepes, P [Rice University, Houston, TX (United States)

    2014-06-15

    Purpose: To develop and validate a fast and accurate four dimensional (4D) Monte Carlo (MC) dose computation system for proton therapy of lung cancer and other thoracic and abdominal malignancies in which the delivered dose distributions can be affected by respiratory motion of the patient. Methods: A 4D computer tomography (CT) scan for a lung cancer patient treated with protons in our clinic was used to create a time dependent patient model using our in-house, MCNPX-based Monte Carlo system (“MC{sup 2}”). The beam line configurations for two passively scattered proton beams used in the actual treatment were extracted from the clinical treatment plan and a set of input files was created automatically using MC{sup 2}. A full MC simulation of the beam line was computed using MCNPX and a set of phase space files for each beam was collected at the distal surface of the range compensator. The particles from these phase space files were transported through the 10 voxelized patient models corresponding to the 10 phases of the breathing cycle in the 4DCT, using MCNPX and an accelerated (fast) MC code called “FDC”, developed by us and which is based on the track repeating algorithm. The accuracy of the fast algorithm was assessed by comparing the two time dependent dose distributions. Results: The error of less than 1% in 100% of the voxels in all phases of the breathing cycle was achieved using this method with a speedup of more than 1000 times. Conclusion: The proposed method, which uses full MC to simulate the beam line and the accelerated MC code FDC for the time consuming particle transport inside the complex, time dependent, geometry of the patient shows excellent accuracy together with an extraordinary speed.

  19. Risk assessment methods in radiotherapy: Probabilistic safety assessment (PSA); Los metodos de analisis de riesgo en radioterapia: Analisis Probabilistico de seguridad (APS)

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez Vera, M. L.; Perez Mulas, A.; Delgado, J. M.; Barrientos Ontero, M.; Somoano, F.; Alvarez Garcia, C.; Rodriguez Marti, M.

    2011-07-01

    The understanding of accidents that have occurred in radiotherapy and the lessons learned from them are very useful to prevent repetition, but there are other risks that have not been detected to date. With a view to identifying and preventing such risks, proactive methods successfully applied in other fields, such as probabilistic safety assessment (PSA), have been developed. (Author)

  20. Shielding assessment of the radiotherapy room of the second egyptian research reactor (ET-RR-2)

    International Nuclear Information System (INIS)

    one of the applications of the ET-RR-2 multipurpose reactor is boron capture therapy. The reactor is provided with a radiotherapy room for patients to be irradiated with thermal neutrons emerging from one of its irradiation tubes. This room has special shield arrangements. The present work is aimed to assess the shielding performance of the above room in the abnormal situation i.e. when the irradiation tube is completely opened (without any collimation of the irradiation beam). One-dimensional ANISN and two-dimensional DOT 3.5 transport codes were used to calculate neutrons as well as primary and secondary gamma fluxes and doses. The cross sections utilized in the ANISN and the dot 3.5 calculations originated the multigroup cross library DLC2 (VITAMIN-C Library) for coupled neutrons and gamma rays. Results were obtained at different distances from the core center up to the front wall of the tumor irradiation room passing through the beam port, the room entrance and around the shielding door and its access entrance. calculations were also done across the room shielding materials to assess its performance. The present results were compared with the design calculations and the actual doses measured during reactor operation at full power

  1. Image-based response assessment of liver metastases following stereotactic body radiotherapy with respiratory tracking

    International Nuclear Information System (INIS)

    To describe post-CyberKnife® imaging characteristics of liver metastases as an aid in assessing response to treatment, and a novel set of combined criteria (CC) as an alternative to response according to change in size (RECIST). Imaging data and medical records of 28 patients with 40 liver metastases treated with stereotactic body radiotherapy (SBRT) were reviewed. Tumor size, CT attenuation coefficient, and contrast enhancement of lesions were evaluated up to 2 years post SBRT. Rates of local control, progression-free survival, time to progression, and overall survival according to RECIST and CC were estimated. Complete response (CR) was 3.6% (95% CI: 0.1–18%) and 18% (95% CI: 6–37%) according to RECIST and combined criteria, respectively. Two progressive diseases and two partial responses according to RECIST were classified as CR by the combined criteria and one stable response according to RECIST was classified as progressive by CC (Stuart-Maxwell test, p = 0.012). The disease control rate was 60.7% (95% CI: 41–78%) by RECIST and 64% (95% CI: 44%–81%) by CC. Use of response criteria based on change in size alone in the interpretation of liver response to SBRT may be inadequate. We propose a simple algorithm with a combination of criteria to better assess tumor response. Further studies are needed to confirm their validity

  2. Texture analysis for the assessment of structural changes in parotid glands induced by radiotherapy

    International Nuclear Information System (INIS)

    Background and purpose: During radiotherapy (RT) for head-and-neck cancer, parotid glands undergo significant anatomic, functional and structural changes which could characterize pre-clinical signs of an increased risk of xerostomia. Texture analysis is proposed to assess structural changes of parotids induced by RT, and to investigate whether early variations of textural parameters (such as mean intensity and fractal dimension) can predict parotid shrinkage at the end of treatment. Material and methods: Textural parameters and volumes of 42 parotids from 21 patients treated with intensity-modulated RT for nasopharyngeal cancer were extracted from CT images. To individuate which parameters changed during RT, a Wilcoxon signed-rank test between textural indices (first and second RT week; first and last RT week) was performed. Discriminant analysis was applied to variations of these parameters in the first two weeks of RT to assess their power in predicting parotid shrinkage at the end of RT. Results: A significant decrease in mean intensity (1.7 HU and 3.8 HU after the second and last weeks, respectively) and fractal dimension (0.016 and 0.021) was found. Discriminant analysis, based on volume and fractal dimension, was able to predict the final parotid shrinkage (accuracy of 71.4%). Conclusion: Textural features could be used in combination with volume to characterize structural modifications on parotid glands and to predict parotid shrinkage at the end of RT

  3. Nutritional status of patients treated with radiotherapy as determined by subjective global assessment

    Energy Technology Data Exchange (ETDEWEB)

    Koom, Woong Sub; Keum, Ki Chang [Dept. of Radiation Oncology, Yonsei University College of Medicine, Seoul (Korea, Republic of); Ahn, Seung Do [Dept. of Radiation Oncology, Asan Medical Center, Seoul (Korea, Republic of); and others

    2012-09-15

    The purpose of this prospective multi-institutional study was to evaluate the nutritional status of patients undergoing radiotherapy (RT) for treatment of head and neck, lung, or gastrointestinal cancer. A total of 1,000 patients were enrolled in this study at seven different hospitals in Seoul, Korea between October 2009 and May 2010. The nutritional status of patients after receiving 3 weeks of RT was evaluated using subjective global assessment (SGA). The nutritional status of each patient was rated as well nourished (A), moderately malnourished (B), or severely malnourished (C). The mean age of patients in this study was 59.4 {+-} 11.9 years, and the male to female ratio was 7:3. According to the SGA results, 60.8%, 34.5%, and 4.7% of patients were classified as A, B, or C, respectively. The following criteria were significantly associated with malnutrition (SGA B or C; p < 0.001): loss of subcutaneous fat or muscle wasting (odds ratio [OR], 11.473); increased metabolic demand/stress (OR, 8.688); ankle, sacral edema, or ascites (OR, 3.234); and weight loss 5% (OR, 2.299). SGA was applied successfully to assess the nutritional status of most patients. The prevalence of malnutrition in a radiation oncology department was 39.2%. The results of this study serve as a basis for implementation of nutrition intervention to patients being treated at radiation oncology departments.

  4. Nutritional status of patients treated with radiotherapy as determined by subjective global assessment

    International Nuclear Information System (INIS)

    The purpose of this prospective multi-institutional study was to evaluate the nutritional status of patients undergoing radiotherapy (RT) for treatment of head and neck, lung, or gastrointestinal cancer. A total of 1,000 patients were enrolled in this study at seven different hospitals in Seoul, Korea between October 2009 and May 2010. The nutritional status of patients after receiving 3 weeks of RT was evaluated using subjective global assessment (SGA). The nutritional status of each patient was rated as well nourished (A), moderately malnourished (B), or severely malnourished (C). The mean age of patients in this study was 59.4 ± 11.9 years, and the male to female ratio was 7:3. According to the SGA results, 60.8%, 34.5%, and 4.7% of patients were classified as A, B, or C, respectively. The following criteria were significantly associated with malnutrition (SGA B or C; p < 0.001): loss of subcutaneous fat or muscle wasting (odds ratio [OR], 11.473); increased metabolic demand/stress (OR, 8.688); ankle, sacral edema, or ascites (OR, 3.234); and weight loss 5% (OR, 2.299). SGA was applied successfully to assess the nutritional status of most patients. The prevalence of malnutrition in a radiation oncology department was 39.2%. The results of this study serve as a basis for implementation of nutrition intervention to patients being treated at radiation oncology departments.

  5. On the Road Towards the Quantum Geometer's Universe: An Introduction to Four-Dimensional Supersymmetric Quantum Field Theories

    OpenAIRE

    Govaerts, Jan

    2004-01-01

    This brief set of notes presents a modest introduction to the basic features entering the construction of supersymmetric quantum field theories in four-dimensional Minkowski spacetime, building a bridge from similar lectures presented at a previous Workshop of this series, and reaching only at the doorstep of the full edifice of such theories.

  6. Four-dimensional magnetic resonance imaging for the determination of tumour movement and its evaluation using a dynamic porcine lung phantom

    Energy Technology Data Exchange (ETDEWEB)

    Remmert, G [Department of Medical Physics in Radiation Oncology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Biederer, J [Department of Radiology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Lohberger, F [Department of Medical Physics in Radiology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Fabel, M [Department of Radiology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany); Hartmann, G H [Department of Medical Physics in Radiation Oncology, German Cancer Research Centre (DKFZ), 69120 Heidelberg (Germany)

    2007-09-21

    A method of four-dimensional (4D) magnetic resonance imaging (MRI) has been implemented and evaluated. It consists of retrospective sorting and slice stacking of two-dimensional (2D) images using an external signal for motion monitoring of the object to be imaged. The presented method aims to determine the tumour trajectories based on a signal that is appropriate for monitoring the movement of the target volume during radiotherapy such that the radiation delivery can be adapted to the movement. For evaluation of the 4D-MRI method, it has been applied to a dynamic lung phantom, which exhibits periodic respiratory movement of a porcine heart-lung explant with artificial pulmonary nodules. Anatomic changes of the lung phantom caused by respiratory motion have been quantified, revealing hysteresis. The results demonstrate the feasibility of the presented method of 4D-MRI. In particular, it enables the determination of trajectories of periodically moving objects with an uncertainty in the order of 1 mm. (note)

  7. Three-dimensional versus four-dimensional dose calculation for volumetric modulated arc therapy of hypofractionated treatments

    International Nuclear Information System (INIS)

    Purpose: Respiratory motion is a non-negligible source of uncertainty in radiotherapy. A common approach is to delineate the target volume in all respiratory phases (ITV) and to calculate a treatment plan using the average reconstruction of the four-dimensional computed tomography (4DCT) scans. In this study the extent of the interplay effect caused by interaction between dynamic dose delivery and respiratory tumor motion, as well as other motion effects were investigated. These effects are often ignored when the ITV concept is used. Methods and Materials: Nine previously treated patients with in ten abdominal or thoracic cancer lesions (3 liver, 3 adrenal glands and 4 lung lesions) were selected for this planning study. For all patients, phase-sorted respiration-correlated 4DCT scans were taken, and volumetric modulated arc therapy (VMAT) treatments were planned using the ITV concept. Margins from ITV to planning target volume (PTV) of 3-10 mm were used. Plans were optimized and dose distributions were calculated on the average reconstruction of the 4DCT. 4D dose distributions were calculated to evaluate motion effects, caused by the interference of dynamic treatment delivery with respiratory tumor motion and inhomogeneously planned target dose. These calculations were performed on the phase-sorted CT series with a respiration-correlated assignment of the treatment plan's monitor units (MU) to the respiration phases of the 4DCT. The 4D dose was accumulated with rigid as well as deformable registrations of the CT series and compared to the original 3D dose distribution. Maximum, minimum and mean doses to ITV and PTV, and maximum or mean doses to organs at risk (OAR), were compared after rigid accumulation. The dose variation in the gross tumor volume (GTV) was compared after deformable registration. Results: Using rigid registrations, variations in the investigated dose parameters between 3D and 4D dose calculations were found to be within -2.1% to 1.4% for

  8. Three-dimensional versus four-dimensional dose calculation for volumetric modulated arc therapy of hypofractionated treatments

    Energy Technology Data Exchange (ETDEWEB)

    Ehrbar, Stefanie; Lang, Stephanie; Stieb, Sonja; Riesterer, Oliver; Stark, Luisa Sabrina; Guckenberger, Matthias; Kloeck, Stephan [University Hospital Zuerich (Switzerland). Dept. of Radiation Oncology

    2016-05-01

    Purpose: Respiratory motion is a non-negligible source of uncertainty in radiotherapy. A common approach is to delineate the target volume in all respiratory phases (ITV) and to calculate a treatment plan using the average reconstruction of the four-dimensional computed tomography (4DCT) scans. In this study the extent of the interplay effect caused by interaction between dynamic dose delivery and respiratory tumor motion, as well as other motion effects were investigated. These effects are often ignored when the ITV concept is used. Methods and Materials: Nine previously treated patients with in ten abdominal or thoracic cancer lesions (3 liver, 3 adrenal glands and 4 lung lesions) were selected for this planning study. For all patients, phase-sorted respiration-correlated 4DCT scans were taken, and volumetric modulated arc therapy (VMAT) treatments were planned using the ITV concept. Margins from ITV to planning target volume (PTV) of 3-10 mm were used. Plans were optimized and dose distributions were calculated on the average reconstruction of the 4DCT. 4D dose distributions were calculated to evaluate motion effects, caused by the interference of dynamic treatment delivery with respiratory tumor motion and inhomogeneously planned target dose. These calculations were performed on the phase-sorted CT series with a respiration-correlated assignment of the treatment plan's monitor units (MU) to the respiration phases of the 4DCT. The 4D dose was accumulated with rigid as well as deformable registrations of the CT series and compared to the original 3D dose distribution. Maximum, minimum and mean doses to ITV and PTV, and maximum or mean doses to organs at risk (OAR), were compared after rigid accumulation. The dose variation in the gross tumor volume (GTV) was compared after deformable registration. Results: Using rigid registrations, variations in the investigated dose parameters between 3D and 4D dose calculations were found to be within -2.1% to 1.4% for

  9. Benchmarking a novel ultrasound-CT fusion system for respiratory motion management in radiotherapy: Assessment of spatio-temporal characteristics and comparison to 4DCT

    International Nuclear Information System (INIS)

    phantom that possessed both high and low contrast test objects. Finally, the system's performance was compared to that of a four-dimensional CT (4DCT) data set. The absolute spatial and display superposition accuracy was found to be better than 2 mm and typically 1 mm. Overall dynamic system response was adequate to produce a mean relative positional error of less than 1 mm if an empiric latency correction of 3 video frames was incorporated. The dynamic CT/US display mode was able to assess phantom motion for both high and low contrast test objects to within 1 mm, and compared favorably to the 4DCT data. The 4DCT movie loop accurately assessed the target motion for both of the high and low contrast objects tested, but the minimum intensity and average intensity reconstructions did not. This investigation demonstrated that this US system possesses sufficient spatio-temporal accuracy to properly assess respiratory motion. Future work will seek to demonstrate efficacy in its clinical application to respiratory motion assessment, particularly for sites in the upper abdomen, where low tissue contrast is evident

  10. GPU-based four-dimensional general-relativistic ray tracing

    Science.gov (United States)

    Kuchelmeister, Daniel; Müller, Thomas; Ament, Marco; Wunner, Günter; Weiskopf, Daniel

    2012-10-01

    This paper presents a new general-relativistic ray tracer that enables image synthesis on an interactive basis by exploiting the performance of graphics processing units (GPUs). The application is capable of visualizing the distortion of the stellar background as well as trajectories of moving astronomical objects orbiting a compact mass. Its source code includes metric definitions for the Schwarzschild and Kerr spacetimes that can be easily extended to other metric definitions, relying on its object-oriented design. The basic functionality features a scene description interface based on the scripting language Lua, real-time image output, and the ability to edit almost every parameter at runtime. The ray tracing code itself is implemented for parallel execution on the GPU using NVidia's Compute Unified Device Architecture (CUDA), which leads to performance improvement of an order of magnitude compared to a single CPU and makes the application competitive with small CPU cluster architectures. Program summary Program title: GpuRay4D Catalog identifier: AEMV_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 73649 No. of bytes in distributed program, including test data, etc.: 1334251 Distribution format: tar.gz Programming language: C++, CUDA. Computer: Linux platforms with a NVidia CUDA enabled GPU (Compute Capability 1.3 or higher), C++ compiler, NVCC (The CUDA Compiler Driver). Operating system: Linux. RAM: 2 GB Classification: 1.5. External routines: OpenGL Utility Toolkit development files, NVidia CUDA Toolkit 3.2, Lua5.2 Nature of problem: Ray tracing in four-dimensional Lorentzian spacetimes. Solution method: Numerical integration of light rays, GPU-based parallel programming using CUDA, 3D

  11. Improved and robust detection of cell nuclei from four dimensional fluorescence images.

    Directory of Open Access Journals (Sweden)

    Md Khayrul Bashar

    Full Text Available Segmentation-free direct methods are quite efficient for automated nuclei extraction from high dimensional images. A few such methods do exist but most of them do not ensure algorithmic robustness to parameter and noise variations. In this research, we propose a method based on multiscale adaptive filtering for efficient and robust detection of nuclei centroids from four dimensional (4D fluorescence images. A temporal feedback mechanism is employed between the enhancement and the initial detection steps of a typical direct method. We estimate the minimum and maximum nuclei diameters from the previous frame and feed back them as filter lengths for multiscale enhancement of the current frame. A radial intensity-gradient function is optimized at positions of initial centroids to estimate all nuclei diameters. This procedure continues for processing subsequent images in the sequence. Above mechanism thus ensures proper enhancement by automated estimation of major parameters. This brings robustness and safeguards the system against additive noises and effects from wrong parameters. Later, the method and its single-scale variant are simplified for further reduction of parameters. The proposed method is then extended for nuclei volume segmentation. The same optimization technique is applied to final centroid positions of the enhanced image and the estimated diameters are projected onto the binary candidate regions to segment nuclei volumes.Our method is finally integrated with a simple sequential tracking approach to establish nuclear trajectories in the 4D space. Experimental evaluations with five image-sequences (each having 271 3D sequential images corresponding to five different mouse embryos show promising performances of our methods in terms of nuclear detection, segmentation, and tracking. A detail analysis with a sub-sequence of 101 3D images from an embryo reveals that the proposed method can improve the nuclei detection accuracy by 9% over

  12. Four dimensional variational assimilation of in-situ and remote-sensing aerosol data

    Science.gov (United States)

    Nieradzik, L. P.; Elbern, H.

    2012-04-01

    Aerosols play an increasingly important role in atmospheric modelling. They have a strong influence on the radiative transfer balance and a significant impact on human health. Their origin is various and so are its effects. Most of the measurement sites in Europe account for an integrated aerosol load PMx (Particulate Matter of less than x μm in diameter) which does not give any qualitative information on the composition of the aerosol. Since very different constituents contribute to PMx, like e.g. mineral dust derived from desert storms or sea salt, it is necessary to make aerosol forecasts not only of load, but also type resolved. The method of four dimensional variational data assimilation (4Dvar) is a widely known technique to enhance forecast skills of CTMs (Chemistry-Transport-Models) by ingesting in-situ and, especially, remote-sensing measurements. The EURAD-IM (EURopean Air pollution Dispersion - Inverse Model), containing a full adjoint gas-phase model, has been expanded with an adjoint of the MADE (Modal Aerosol Dynamics model for Europe) to optimise initial and boundary values for aerosols using 4Dvar. A forward and an adjoint radiative transfer model is driven by the EURAD-IM as mapping between BLAOT (Boundary Layer Aerosol Optical Thickness) and internal aerosol species. Furthermore, its condensation scheme has been bypassed by an HDMR (High-Dimensional-Model-Representation) to ensure differentiability. In this study both in-situ measured PMx as well as satellite retrieved aerosol optical thicknesses have been assimilated and the effect on forecast performance has been investigated. The source of BLAOT is the aerosol retrieval system SYNAER (SYNergetic AErosol Retrieval) from DLR-DFD that retrieves AOT by making use of both AATSR/SCIAMACHY and AVHRR/GOME-2 data respectively. Its strengths are a large spatial coverage, near real-time availability, and the classification of five intrinsic aerosol species, namely water-solubles, water-insolubles, soot

  13. Certification of health care organisations, assessment of professional practices and external radiotherapy

    International Nuclear Information System (INIS)

    In France, accreditation of health care organisations (HCOs) is mandatory every 4 years. It is based on a systemic approach and, since 2004, includes professional practice appraisal (EPP) against good practice guidelines. However, following an incident in Epinal, a new quality assurance criterion was introduced in 2007 for external radiotherapy (ERT) on top of the annual inspection of patient radiation protection by the Nuclear Safety Authority. In the accreditation procedure starting January 2010, ERT work organisation will come under 'high-risk activity' (criterion 26b) and radio-vigilance will be included in the adverse events reporting system (8i). In addition, ERT will have to comply with many generic criteria on quality and safety improvement. For example, practice appraisal of all clinical activities will become routine. Thus, besides self-assessment against criteria 26b and 8i, ERT professionals will have report the impact of their quality improvement actions on patient care. They will be able to freely choose the area for improvement, as long as it is in line with the HCO's overall quality and safety plan. In oncology, multidisciplinary team meetings for deciding on the treatment plan, as well as mortality and morbidity meetings providing feedback, are compulsory (28a). Appraisal of appropriateness of care (28b) and indicator-based practice appraisal (28c) complete the process. In conclusion, the generic practice appraisal approach that is part of the French HCO accreditation procedure can contribute toward improving health care and education, but it has not been designed for in-depth assessment of complex, multidisciplinary clinical practice such as ERT. Such assessment requires a specific clinical audit and specialized auditors. (authors)

  14. Assessment of rectal distention in radiotherapy of prostate cancer using daily megavoltage CT image guidance

    International Nuclear Information System (INIS)

    Purpose: Assessment of rectal distention in a group of patients who are not receiving daily rectum emptying procedures during a course of prostate cancer radiotherapy to investigate which patients could benefit from daily rectum emptying. Methods and materials: Eighteen patients underwent daily megavoltage CT (MVCT) scanning with positioning based on bony anatomy. Emptying the rectum was only performed before planning CT and not during the actual treatment. The rectal average cross-sectional area (CSA) was determined on the MVCTs. The relative CSA (CSArel) was defined as CSA on MVCT / CSA on planning CT. Additional prostate soft tissue matching was performed to verify the influence of rectal distention on prostate motion. Results: Two distinct subgroups could be defined a posteriori. One group had a limited and stable rectal distention with a CSA (mean ± SD) of 6.6 ± 2.1 cm2, in contrast with a second group with large and variable rectal filling with a CSA of 9.5 ± 3.7 cm2 (p rel of 1.35 of the first 3 days as cut-off value allowed for a correct a priori classification of 90% and 85% of the patients from groups 1 and 2, respectively. Conclusion: Based on a few measurements of the CSA by daily MVCT imaging at the first days of treatment, rectum emptying may be omitted in part of the patients

  15. Results of postoperative 90Sr radiotherapy of keloids in view of patients' subjective assessment

    International Nuclear Information System (INIS)

    Background and Purpose: As treatment of keloids is mainly a cosmetic indication, the authors investigated, beyond the recurrence rate, the patients' satisfaction with the result and its correlation with objective medical findings. Patients and Methods: 83 keloids of 66 patients had been irradiated after excision by a uniform protocol with 4 x 5 Gy (strontium-90 [90Sr] surface applicator). A questionnaire was developed and sent out in which, above all, the satisfaction with the therapeutic and cosmetic outcome was obtained. These results were correlated with objective parameters and medical findings which were ascertained during an extra follow-up examination. Results: Among 18 of the 41 patients (44%), who had answered the questionnaire, 19 of the 53 keloids treated (36%) had relapsed. 61% of the patients were extremely or mainly satisfied with the therapeutic outcome, 51% extremely or mainly satisfied with the cosmetic outcome. The relief from former keloid-caused symptoms (therapeutic outcome: p=0.0005; cosmetic outcome: p=0.0011), the ear as keloid localization (p=0.0008 and p=0.0197), and male gender (therapeutic outcome: p=0.0423) were significantly associated with higher satisfaction. The recurrence rate as well as the extent of radiation side effects had no significant influence on patients' assessment. Conclusion: Cosmetic aspects like the dermal side effects and the patients' satisfaction should be taken into account when evaluating the results of radiotherapy in keloids. (orig.)

  16. Tumor shrinkage assessed by volumetric MRI in the long-term follow-up after stereotactic radiotherapy of meningiomas

    Energy Technology Data Exchange (ETDEWEB)

    Astner, Sabrina T.; Theodorou, Marilena; Dobrei-Ciuchendea, Mihaela; Kopp, Christine; Molls, Michael [Dept. of Radiotherapy and Radiooncology, Klinikum rechts der Isar, Technical Univ. of Munich (Germany); Auer, Florian [Dept. of Neuroradiology, Klinikum rechts der Isar, Technical Univ. of Munich (Germany); Grosu, Anca-Ligia [Dept. of Radiotherapy, Univ. Hospital Freiburg (Germany)

    2010-08-15

    Purpose: To evaluate tumor volume reduction in the follow-up of meningiomas after fractionated stereotactic radiotherapy (FSRT) or linac radiosurgery (RS) by using magnetic resonance imaging (MRI). Patients and Methods: In 59 patients with skull base meningiomas, gross tumor volume (GTV) was outlined on contrast-en-hanced MRI before and median 50 months (range 11-92 months) after stereotactic radiotherapy. MRI was performed as an axial three-dimensional gradient-echo T1-weighted sequence at 1.6 mm slice thickness without gap (3D-MRI). Results were compared to the reports of diagnostic findings. Results: Mean tumor size of all 59 meningiomas was 13.9 ml (0.8-62.9 ml) before treatment. There was shrinkage of the treated meningiomas in all but one patient. Within a median volumetric follow-up of 50 months (11-95 months), an absolute mean volume reduction of 4 ml (0-18 ml) was seen. The mean relative size reduction compared to the volume before radiotherapy was 27% (0-73%). Shrinkage measured by 3D-MRI was greater at longer time intervals after radiotherapy. The mean size reduction was 17%, 23%, and 30% (at < 24 months, 24-48 months, and 48-72 months). Conclusion: By using 3D-MRI in almost all patients undergoing radiotherapy of a meningioma, tumor shrinkage is detected. The data presented here demonstrate that volumetric assessment from 3D-MRI provides additional information to routinely used radiologic response measurements. After FSRT or RS, a mean size reduction of 25-45% can be expected within 4 years. (orig.)

  17. Four-dimensional cone beam CT reconstruction and enhancement using a temporal nonlocal means method

    International Nuclear Information System (INIS)

    Purpose: Four-dimensional cone beam computed tomography (4D-CBCT) has been developed to provide respiratory phase-resolved volumetric imaging in image guided radiation therapy. Conventionally, it is reconstructed by first sorting the x-ray projections into multiple respiratory phase bins according to a breathing signal extracted either from the projection images or some external surrogates, and then reconstructing a 3D CBCT image in each phase bin independently using FDK algorithm. This method requires adequate number of projections for each phase, which can be achieved using a low gantry rotation or multiple gantry rotations. Inadequate number of projections in each phase bin results in low quality 4D-CBCT images with obvious streaking artifacts. 4D-CBCT images at different breathing phases share a lot of redundant information, because they represent the same anatomy captured at slightly different temporal points. Taking this redundancy along the temporal dimension into account can in principle facilitate the reconstruction in the situation of inadequate number of projection images. In this work, the authors propose two novel 4D-CBCT algorithms: an iterative reconstruction algorithm and an enhancement algorithm, utilizing a temporal nonlocal means (TNLM) method. Methods: The authors define a TNLM energy term for a given set of 4D-CBCT images. Minimization of this term favors those 4D-CBCT images such that any anatomical features at one spatial point at one phase can be found in a nearby spatial point at neighboring phases. 4D-CBCT reconstruction is achieved by minimizing a total energy containing a data fidelity term and the TNLM energy term. As for the image enhancement, 4D-CBCT images generated by the FDK algorithm are enhanced by minimizing the TNLM function while keeping the enhanced images close to the FDK results. A forward–backward splitting algorithm and a Gauss–Jacobi iteration method are employed to solve the problems. The algorithms implementation

  18. A Novel Four-Dimensional Energy-Saving and Emission-Reduction System and Its Linear Feedback Control

    OpenAIRE

    Minggang Wang; Hua Xu

    2012-01-01

    This paper reports a new four-dimensional energy-saving and emission-reduction chaotic system. The system is obtained in accordance with the complicated relationship between energy saving and emission reduction, carbon emission, economic growth, and new energy development. The dynamics behavior of the system will be analyzed by means of Lyapunov exponents and equilibrium points. Linear feedback control methods are used to suppress chaos to unstable equilibrium. Numerical sim...

  19. Four-dimensional visualization of subpleural alveolar dynamics in vivo during uninterrupted mechanical ventilation of living swine

    OpenAIRE

    Namati, Eman; Warger, William C.; Unglert, Carolin I.; Eckert, Jocelyn E.; Hostens, Jeroen; Bouma, Brett E.; Tearney, Guillermo J.

    2013-01-01

    Pulmonary alveoli have been studied for many years, yet no unifying hypothesis exists for their dynamic mechanics during respiration due to their miniature size (100-300 μm dimater in humans) and constant motion, which prevent standard imaging techniques from visualizing four-dimensional dynamics of individual alveoli in vivo. Here we report a new platform to image the first layer of air-filled subpleural alveoli through the use of a lightweight optical frequency domain imaging (OFDI) probe t...

  20. Comparison of planning target volumes based on three-dimensional and four-dimensional CT imaging of thoracic esophageal cancer

    OpenAIRE

    Wang, Wei; LI, JIANBIN; Zhang, Yingjie; SHAO, QIAN; Xu, Min; Fan, Tingyong; Wang, Jinzhi

    2016-01-01

    Wei Wang, Jianbin Li, Yingjie Zhang, Qian Shao, Min Xu, Tingyong Fan, Jinzhi Wang Department of Radiation Oncology, Shandong Cancer Hospital Affiliated to Shandong University, Shandong Academy of Medical Sciences, Shandong, People’s Republic of China Background and purpose: To investigate the definition of planning target volumes (PTVs) based on four-dimensional computed tomography (4DCT) compared with conventional PTV definition and PTV definition using asymmetrical margins for t...

  1. Objective assessment of deformable image registration in radiotherapy: A multi-institution study

    International Nuclear Information System (INIS)

    The looming potential of deformable alignment tools to play an integral role in adaptive radiotherapy suggests a need for objective assessment of these complex algorithms. Previous studies in this area are based on the ability of alignment to reproduce analytically generated deformations applied to sample image data, or use of contours or bifurcations as ground truth for evaluation of alignment accuracy. In this study, a deformable phantom was embedded with 48 small plastic markers, placed in regions varying from high contrast to roughly uniform regional intensity, and small to large regional discontinuities in movement. CT volumes of this phantom were acquired at different deformation states. After manual localization of marker coordinates, images were edited to remove the markers. The resulting image volumes were sent to five collaborating institutions, each of which has developed previously published deformable alignment tools routinely in use. Alignments were done, and applied to the list of reference coordinates at the inhale state. The transformed coordinates were compared to the actual marker locations at exhale. A total of eight alignment techniques were tested from the six institutions. All algorithms performed generally well, as compared to previous publications. Average errors in predicted location ranged from 1.5 to 3.9 mm, depending on technique. No algorithm was uniformly accurate across all regions of the phantom, with maximum errors ranging from 5.1 to 15.4 mm. Larger errors were seen in regions near significant shape changes, as well as areas with uniform contrast but large local motion discontinuity. Although reasonable accuracy was achieved overall, the variation of error in different regions suggests caution in globally accepting the results from deformable alignment.

  2. Assessment of low-dose radiotherapy (two 2 Gy sessions) for the cure of MALT lymphoma of the lung; evaluation de la radiotherapie faible (deux seances de 2 Gy) a visee curative dans le lymphome du Malt pulmonaire

    Energy Technology Data Exchange (ETDEWEB)

    Paumier, A.; Ghalibafian, M.; Gilmore, J.; Girinsky, T. [Departement de radiotherapie, institut de cancerologie Gustave-Roussy, Villejuif (France); Hanna, C.; Raphael, J.; Ferme, C.; Ribrag, V. [Departement d' hematologie, institut de cancerologie Gustave-Roussy, Villejuif (France)

    2011-10-15

    The authors report the assessment of low-dose radiotherapy (two sessions of 2 Gy in two days) for the curative treatment of mucosa-associated lymphoid tissue (MALT) lymphoma of the lung. The treatment of this lymphoma is discussed in terms of surgery, chemotherapy, radiotherapy, or even simple monitoring. The authors analyse the results obtained on nine patients who have been treated this way since 2002, straight away for some of them, after surgery or chemotherapy for others. Survival rate, recurrence, evolutions and responses are discussed. Short communication

  3. Assessment of thyroid function in patients with laryngeal carcinoma treated surgically and with radiotherapy

    International Nuclear Information System (INIS)

    In 40 patients with laryngeal carcinoma after total laryngectomy and radiotherapy the triiodotyronine binding index, total thyroxine level, serum free thyroxine index were determined before, during and after treatment. At the same time thyroid iodine uptake was determined by the routine method. Surgical treatment as well as radiotherapy caused lowering of thyroid functions. These changes had a high tendency for return to normal values, not earlier, however, than 6 months after treatment. The authors stress that endocrine thyroid disturbances may have an important influence on delay of psychic rehabilitation and speech training in laryngectomized patients. (author)

  4. Randomized controlled trial to assess the effectiveness of a videotape about radiotherapy

    OpenAIRE

    Harrison, R; Dey, P.; Slevin, N J; Eardley, A; Gibbs, A; Cowan, R.; Logue, J P; Leidecker, V; Hopwood, P

    2001-01-01

    In a randomized controlled trial, the additional provision of information on videotape was no more effective than written information alone in reducing pre-treatment worry about radiotherapy. Images of surviving cancer patients, however, may provide further reassurance to patients once therapy is completed. © 2001 Cancer Research Campaign http://www.bjcancer.com

  5. Assessment of Olfactory Threshold in Patients Undergoing Radiotherapy for Head and Neck Malignancies

    Directory of Open Access Journals (Sweden)

    Mir Mohammad Jalali

    2014-10-01

    Conclusion:  Deterioration in olfactory threshold scores was found at 6 months after initiation of radiation therapy. Provided that these results are reproducible, an evaluation of olfactory functioning in patients with head and neck malignancies using in vivo dosimetry may be useful for determining the optimal dose for patients treated with conformal radiotherapy techniques while avoiding the side effects of radiation.

  6. K-orbits, identity and classification of four-dimensional uniform space with group of Poincare and de Sitter transformations

    International Nuclear Information System (INIS)

    The method of orbits, traditionally employed in problems of geometric quantization in this study is used for analyzing uniform spaces. On the basis of suggested classification of co-associated presentation of orbits (K-orbits) the classification of homogeneous spaces is constructed. Specially, this classification permits indication of explicit type of identity of functional ratios between generators of transformation group, which are of great importance in applied problems (in the theory of variables separation, in particular). All four-dimensional uniform spaces with the Poincare and de Sitter transformation group were classified, explicit form of all independent identities in the spaces being provided

  7. A four-dimensional lambda CDM-type cosmological model induced from higher dimensions using a kinematical constraint

    OpenAIRE

    Dereli, Tekin; Akarsu, Özgür

    2013-01-01

    arXiv:1201.4545v3 [gr-qc] 31 Mar 2013 A four-dimensional CDM-type cosmological model induced from higher dimensions using a kinematical constraint Özgür Akarsu, Tekin Dereli Department of Physics, Koç University, 34450 Sarıyer, İstanbul, Turkey Abstract A class of cosmological solutions of higher dimensional Einstein field equations with the energy-momentum tensor of a homogeneous, isotropic fluid as the source are considered with an anisotropic metric that includes t...

  8. Four-dimensional anti-de Sitter black holes from a three-dimensional perspective Full complexity

    CERN Document Server

    Zanchin, V T; Lemos, J P S

    2002-01-01

    The dimensional reduction of black hole solutions in four-dimensional (4D) general relativity is performed and new 3D black hole solutions are obtained. Considering a 4D spacetime with one spacelike Killing vector, it is possible to split the Einstein-Hilbert-Maxwell action with a cosmological term in terms of 3D quantities. Definitions of quasilocal mass and charges in 3D spacetimes are reviewed. The analysis is then particularized to the toroidal charged rotating anti-de Sitter black hole. The reinterpretation of the fields and charges in terms of a three-dimensional point of view is given in each case, and the causal structure analyzed.

  9. Non-Gaussian Fixed Point in Four-Dimensional Pure Compact U(1) Gauge Theory on the Lattice

    International Nuclear Information System (INIS)

    The line of phase transitions separating the confinement phase from the Coulomb phase in the four-dimensional pure compact U(1) gauge theory with extended Wilson action is reconsidered. By means of a high precision simulation on spherical lattices and a finite-size scaling analysis we find that along a part of this line, including the Wilson action the critical scaling behavior is determined by one fixed point with non-Gaussian critical exponent ν=0.365(8). This indicates the existence of a nontrivial and nonasymptotically free continuum limit of this theory, as well as of its dual equivalent. copyright 1996 The American Physical Society

  10. Equations of motion for the scalar and the spinor fields in four-dimensional momeuclidean momentum space

    International Nuclear Information System (INIS)

    Equations of motion for scalar and spinor fields in a four-dimensional non-Euclidean momentum space are obtained. These equations incorporate as a parameter the fundamental length and coincide with the ordinary Klein-Gordon and Dirac equations in the limiting case l → 0. In the new formalism an important role is played by ''vacuum momentum'' (this notion is introduced by I.E. Tamm). The equations obtained remain invariant under the space inversion only if the vacuum momentum transforms simultaneously

  11. Real-time volume rendering of four-dimensional images based on three-dimensional texture mapping

    OpenAIRE

    Hwang, Jinwoo; Kim, June Sic; Kim, Jae Seok; Kim, In Young; Kim, Sun I.

    2001-01-01

    A four-dimensional (4-D) image consists of three-dimensional (3-D) volume data that varies with time. It is used to express a deforming or moving object in virtual surgery or 4-D ultrasound. It is difficult to obtain 4-D images by conventional ray-casting or shear-warp factorization methods because of their time-consuming rendering process and the pre-processing stage necessary whenever the volume data are changed. Even when 3-D texture mapping is used, repeated volume loading is time-consumi...

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

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

    2006-09-01

    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

  14. Toward Semi-automated Assessment of Target Volume Delineation in Radiotherapy Trials: The SCOPE 1 Pretrial Test Case

    Energy Technology Data Exchange (ETDEWEB)

    Gwynne, Sarah, E-mail: Sarah.Gwynne2@wales.nhs.uk [Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, Wales (United Kingdom); Spezi, Emiliano; Wills, Lucy [Department of Medical Physics, Velindre Cancer Centre, Cardiff, Wales (United Kingdom); Nixon, Lisette; Hurt, Chris [Wales Cancer Trials Unit, School of Medicine, Cardiff University, Cardiff, Wales (United Kingdom); Joseph, George [Department of Diagnostic Radiology, Velindre Cancer Centre, Cardiff, Wales (United Kingdom); Evans, Mererid [Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, Wales (United Kingdom); Griffiths, Gareth [Wales Cancer Trials Unit, School of Medicine, Cardiff University, Cardiff, Wales (United Kingdom); Crosby, Tom [Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, Wales (United Kingdom); Staffurth, John [Division of Cancer, School of Medicine, Cardiff University, Cardiff, Wales (United Kingdom)

    2012-11-15

    Purpose: To evaluate different conformity indices (CIs) for use in the analysis of outlining consistency within the pretrial quality assurance (Radiotherapy Trials Quality Assurance [RTTQA]) program of a multicenter chemoradiation trial of esophageal cancer and to make recommendations for their use in future trials. Methods and Materials: The National Cancer Research Institute SCOPE 1 trial is an ongoing Cancer Research UK-funded phase II/III randomized controlled trial of chemoradiation with capecitabine and cisplatin with or without cetuximab for esophageal cancer. The pretrial RTTQA program included a detailed radiotherapy protocol, an educational package, and a single mid-esophageal tumor test case that were sent to each investigator to outline. Investigator gross tumor volumes (GTVs) were received from 50 investigators in 34 UK centers, and CERR (Computational Environment for Radiotherapy Research) was used to perform an assessment of each investigator GTV against a predefined gold-standard GTV using different CIs. A new metric, the local conformity index (l-CI), that can localize areas of maximal discordance was developed. Results: The median Jaccard conformity index (JCI) was 0.69 (interquartile range, 0.62-0.70), with 14 of 50 investigators (28%) achieving a JCI of 0.7 or greater. The median geographical miss index was 0.09 (interquartile range, 0.06-0.16), and the mean discordance index was 0.27 (95% confidence interval, 0.25-0.30). The l-CI was highest in the middle section of the volume, where the tumor was bulky and more easily definable, and identified 4 slices where fewer than 20% of investigators achieved an l-CI of 0.7 or greater. Conclusions: The available CIs analyze different aspects of a gold standard-observer variation, with JCI being the most useful as a single metric. Additional information is provided by the l-CI and can focus the efforts of the RTTQA team in these areas, possibly leading to semi-automated outlining assessment.

  15. Validation of four-dimensional ultrasound for targeting in minimally-invasive beating-heart surgery

    Science.gov (United States)

    Pace, Danielle F.; Wiles, Andrew D.; Moore, John; Wedlake, Chris; Gobbi, David G.; Peters, Terry M.

    2009-02-01

    Ultrasound is garnering significant interest as an imaging modality for surgical guidance, due to its affordability, real-time temporal resolution and ease of integration into the operating room. Minimally-invasive intracardiac surgery performed on the beating-heart prevents direct vision of the surgical target, and procedures such as mitral valve replacement and atrial septal defect closure would benefit from intraoperative ultrasound imaging. We propose that placing 4D ultrasound within an augmented reality environment, along with a patient-specific cardiac model and virtual representations of tracked surgical tools, will create a visually intuitive platform with sufficient image information to safely and accurately repair tissue within the beating heart. However, the quality of the imaging parameters, spatial calibration, temporal calibration and ECG-gating must be well characterized before any 4D ultrasound system can be used clinically to guide the treatment of moving structures. In this paper, we describe a comprehensive accuracy assessment framework that can be used to evaluate the performance of 4D ultrasound systems while imaging moving targets. We image a dynamic phantom that is comprised of a simple robot and a tracked phantom to which point-source, distance and spherical objects of known construction can be attached. We also follow our protocol to evaluate 4D ultrasound images generated in real-time by reconstructing ECG-gated 2D ultrasound images acquired from a tracked multiplanar transesophageal probe. Likewise, our evaluation framework allows any type of 4D ultrasound to be quantitatively assessed.

  16. Motion of particles on a Four-Dimensional Asymptotically AdS Black Hole with Scalar Hair

    CERN Document Server

    Gonzalez, P A; Vasquez, Yerko

    2015-01-01

    Motivated by black hole solutions with matter fields outside their horizon, we study the effect of these matter fields in the motion of massless and massive particles. We consider as background a four-dimensional asymptotically AdS black hole with scalar hair. The geodesics are studied numerically and we discuss about the differences in the motion of particles between the four-dimensional asymptotically AdS black holes with scalar hair and their no-hair limit, that is, Schwarzschild AdS black holes. Mainly, we found that there are bounded orbits like planetary orbits in this background. However, the periods associated to circular orbits are modified by the presence of the scalar hair. Besides, we found that some classical tests such as perihelion precession, deflection of light and gravitational time delay have the standard value of general relativity plus a correction term coming from the cosmological constant and the scalar hair. Finally, we found a specific value of the parameter associated to the scalar h...

  17. Analysis on the computability over the efficient utilization problem of the four-dimensional space-time

    CERN Document Server

    Huang, Wenqi

    2011-01-01

    This paper formally proposes a problem about the efficient utilization of the four dimensional space-time. Given a cuboid container, a finite number of rigid cuboid items, and the time length that each item should be continuous baked in the container, the problem asks to arrange the starting time for each item being placed into the container and to arrange the position and orientation for each item at each instant during its continuous baking period such that the total time length the container be utilized is as short as possible. Here all side dimensions of the container and of the items are positive real numbers arbitrarily given. Differs from the classical packing problems, the position and orientation of each item in the container could be changed over time. Therefore, according to above mathematical model, the four-dimensional space-time can be utilized more truly and more fully. This paper then proves that there exists an exact algorithm that could solve the problem by finite operations, so we say this ...

  18. Modeling of the World Ocean circulation with the four-dimensional assimilation of temperature and salinity fields

    Science.gov (United States)

    Marchuk, G. I.; Zalesny, V. B.

    2012-02-01

    The problem of modeling the World Ocean circulation with the four-dimensional assimilation of temperature and salinity fields is considered. A mathematical model of the ocean general circulation and a numerical algorithm for its solution are formulated. The model equations are written in a σ coordinate system on the sphere with the North Pole shifted to the point of the continent (60° E, 60.5° N). The model has a flexible numerical structure and consists of two parts: the forward prognostic model and its adjoint analog. The numerical algorithm for solving the forward and adjoint problems is based on the method of multicomponent splitting. This method includes splitting with respect to physical processes and geometric coordinates. Three series of numerical experiments are performed: (1) a test solution to the problem of the four-dimensional variational assimilation, (2) modeling of the World Ocean circulation with the variational assimilation of climatic temperature and salinity fields, and (3) modeling of the World Ocean circulation with the variational assimilation of climatic temperature and salinity fields and the data of Argo buoys. The results of calculations demonstrate the expediency of using the model of World Ocean circulation with the procedure of assimilating observational data for a description of the general structure of thermohaline fields.

  19. An explicit four-dimensional variational data assimilation method based on the proper orthogonal decomposition: Theoretics and evaluation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The proper orthogonal decomposition (POD) method is used to construct a set of basis functions for spanning the ensemble of data in a certain least squares optimal sense. Compared with the singular value decomposition (SVD), the POD basis functions can capture more energy in the forecast ensemble space and can represent its spatial structure and temporal evolution more effectively. After the analysis variables are expressed by a truncated expansion of the POD basis vectors in the ensemble space, the control variables appear explicitly in the cost function, so that the adjoint model, which is used to de-rive the gradient of the cost function with respect to the control variables, is no longer needed. The application of this new technique significantly simplifies the data assimilation process. Several as-similation experiments show that this POD-based explicit four-dimensional variational data assimila-tion method performs much better than the usual ensemble Kalman filter method on both enhancing the assimilation precision and reducing the computation cost. It is also better than the SVD-based ex-plicit four-dimensional assimilation method, especially when the forecast model is not perfect and the forecast error comes from both the noise of the initial filed and the uncertainty of the forecast model.

  20. Motion of particles on a four-dimensional asymptotically AdS black hole with scalar hair

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, P.A.; Olivares, Marco [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)

    2015-10-15

    Motivated by black hole solutions with matter fields outside their horizon, we study the effect of these matter fields on the motion of massless and massive particles. We consider as background a four-dimensional asymptotically AdS black hole with scalar hair. The geodesics are studied numerically and we discuss the differences in the motion of particles between the four-dimensional asymptotically AdS black holes with scalar hair and their no-hair limit, that is, Schwarzschild AdS black holes. Mainly, we found that there are bounded orbits like planetary orbits in this background. However, the periods associated to circular orbits are modified by the presence of the scalar hair. Besides, we found that some classical tests such as perihelion precession, deflection of light, and gravitational time delay have the standard value of general relativity plus a correction term coming from the cosmological constant and the scalar hair. Finally, we found a specific value of the parameter associated to the scalar hair, in order to explain the discrepancy between the theory and the observations, for the perihelion precession of Mercury and light deflection. (orig.)

  1. Chemo-radiotherapy induced oral mucositis during IMRT for head and neck cancer: an assessment

    OpenAIRE

    Nagarajan, Karthika

    2015-01-01

    Background This study is conducted mainly to evaluate the changes in quality and quantity of oral epithelial cells during the course of IMRT. Material and Methods 30 Patients undergoing chemo-radiotherapy were followed through course of treatment. They were compared with a group of age- and sex-matched healthy individuals. The procedure involved WHO clinical scoring, collection of oral washings and preparation of buccal smears from both study group and control group. The changes occurred were...

  2. Application of four dimensional matrix for thermal analysis of Slovak transit gas pipeline by program FENIX

    Science.gov (United States)

    Széplaky, Dávid; Varga, Augustín

    2016-06-01

    The contribution describes the principle of the FENIX program operation, which was designed to determine the temperature field of the transit pipeline for the transportation of natural gas. The program itself consists of several modules which are reciprocally linked. The basis of the program is the elementary balance method by means of which the unsteady heat transfer is assigned in several layers in different directions. The first step was to assess both the pressure and temperature of the natural gas mode, the second step is to determine the heat transfer through the walls of the pipes, and the last one is to determine the distribution of the temperature field in the surroundings of the pipeline.

  3. A brief survey of the renormalizability of four dimensional gravity for generalized Kodama states

    CERN Document Server

    Ita, Eyo Eyo

    2008-01-01

    We continue the line of research from previous works in assessing the suitability of the pure Kodama state both as a ground state for the generalized Kodama states, as well as characteristic of a good semiclassical limit of general relativity. We briefly introduce the quantum theory of fluctuations about DeSitter spacetime, which enables one to examine some perturbative aspects of the state. Additionally, we also motivate the concept of the cubic tree network, which enables one to view the generalized Kodama states in compact form as a nonlinear transformation of the pure Kodama states parametrized by the matter content of the proper classical limit. It is hoped that this work constitutes a first step in addressing the nonperturbative renormalizability of general relativity in Ashtekar variables. Remaining issues to address, including the analysis of specific matter models, include finiteness and normalizability of the generalized Kodama state as well as reality conditions on the Ashtekar variables, which we ...

  4. Four-Dimensional Patient Dose Reconstruction for Scanned Ion Beam Therapy of Moving Liver Tumors

    International Nuclear Information System (INIS)

    Purpose: Estimation of the actual delivered 4-dimensional (4D) dose in treatments of patients with mobile hepatocellular cancer with scanned carbon ion beam therapy. Methods and Materials: Six patients were treated with 4 fractions to a total relative biological effectiveness (RBE)–weighted dose of 40 Gy (RBE) using a single field. Respiratory motion was addressed by dedicated margins and abdominal compression (5 patients) or gating (1 patient). 4D treatment dose reconstructions based on the treatment records and the measured motion monitoring data were performed for the single-fraction dose and a total of 17 fractions. To assess the impact of uncertainties in the temporal correlation between motion trajectory and beam delivery sequence, 3 dose distributions for varying temporal correlation were calculated per fraction. For 3 patients, the total treatment dose was formed from the fractional distributions using all possible combinations. Clinical target volume (CTV) coverage was analyzed using the volumes receiving at least 95% (V95) and 107% (V107) of the planned doses. Results: 4D dose reconstruction based on daily measured data is possible in a clinical setting. V95 and V107 values for the single fractions ranged between 72% and 100%, and 0% and 32%, respectively. The estimated total treatment dose to the CTV exhibited improved and more robust dose coverage (mean V95 > 87%, SD < 3%) and overdose (mean V107 < 4%, SD < 3%) with respect to the single-fraction dose for all analyzed patients. Conclusions: A considerable impact of interplay effects on the single-fraction CTV dose was found for most of the analyzed patients. However, due to the fractionated treatment, dose heterogeneities were substantially reduced for the total treatment dose. 4D treatment dose reconstruction for scanned ion beam therapy is technically feasible and may evolve into a valuable tool for dose assessment

  5. An attempt at assessing the quality of radiotherapy based on the analysis of irradiation therapy plans in five children with stage IV neuroblastoma

    International Nuclear Information System (INIS)

    Radiotherapy treatment quality is of paramount importance in preventing local relapses and late radiotherapy complications, especially those involving normal tissues near the primary tumor. To assess the quality of irradiation treatment in five children with stage IV neuroblastoma based on the adherence to radiotherapy protocol recommendations and the evaluation of problems associated with protocol implementation. The analysis included plans of irradiation therapy in five children with stage IV neuroblastoma, three of whom had been treated at the University Children's Hospital of Cracow, and two - in other Polish radiotherapy centers. The most common protocol deviation was the use of oblique fields rather than the recommended AP-opposite fields technique, followed by a failure to plan the therapy basing on preoperative CT scans. Other technical problems involved the inability of fusing pre and postoperative CT scans, as well as the inability of recording treatment plans on discs or CD's. Participation in international multicenter clinical trials significantly improves the quality of treatment. One should strive for better collaboration between pediatric centers and radiotherapy departments. Pediatric radiotherapy should be provided by highly specialised centers with appropriate knowledge and equipment. Even in the course of protocol implementation, its strict assumptions may be changed for the benefit of the patients. (author)

  6. Intraoperative radiotherapy

    International Nuclear Information System (INIS)

    The potential benefit of intraoperative radiotherapy (IORT) was originally recognized years ago and has recently attracted renewed interest. Modern radiotherapeutic approaches may be more successful as a result of technical innovation, particularly in the use of electron beam accelerators. Preliminary studies, mainly uncontrolled and nonrandomized, have assessed the role of IORT for treatment of a variety of deep seated abdominal, retroperitoneal, and pelvic cancers. The results of some studies show much promise, but prospective trials are needed to scientifically validate these favorable initial observations. (Auth.)

  7. Investigating the Impact on Modeled Ozone Concentrations Using Meteorological Fields From WRF With and Updated Four-Dimensional Data Assimilation Approach”

    Science.gov (United States)

    The four-dimensional data assimilation (FDDA) technique in the Weather Research and Forecasting (WRF) meteorological model has recently undergone an important update from the original version. Previous evaluation results have demonstrated that the updated FDDA approach in WRF pr...

  8. Intensity-modulated radiotherapy, not 3D conformal, is the preferred technique for treating locally advanced lung cancer

    OpenAIRE

    Chang, Joe Y.

    2014-01-01

    When used to treat lung cancer, intensity-modulated radiotherapy (IMRT) can deliver higher dose to the targets and spare more critical organs in lung cancer than can 3D conformal radiotherapy (3DCRT). However, tumor-motion management and optimized radiotherapy planning based on four-dimensional computed tomography (4D CT) scanning are crucial to maximize the benefit of IMRT and to eliminate or minimize potential uncertainties. This article summarizes these strategies and reviews published fin...

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

    Energy Technology Data Exchange (ETDEWEB)

    Blackall, J M [Centre for Medical Image Computing, University College London, WC1E 6BT (United Kingdom); Ahmad, S [Department of Radiotherapy, Guy' s and St. Thomas' Trust, London, SE1 7EH (United Kingdom); Miquel, M E [Division of Imaging Sciences, GKT Schools of Medicine, London, SE1 9RT (United Kingdom); McClelland, J R [Centre for Medical Image Computing, University College London, WC1E 6BT (United Kingdom); Landau, D B [Department of Radiotherapy, Guy' s and St. Thomas' Trust, London, SE1 7EH (United Kingdom); Hawkes, D J [Centre for Medical Image Computing, University College London, WC1E 6BT (United Kingdom)

    2006-09-07

    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

  10. Systematic evaluation of four-dimensional hybrid depth scanning for carbon-ion lung therapy

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Shinichiro; Furukawa, Takuji; Inaniwa, Taku; Zenklusen, Silvan; Nakao, Minoru; Shirai, Toshiyuki; Noda, Koji [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555 (Japan)

    2013-03-15

    also improved dose homogeneity with higher numbers of rescannings. Dose distributions with single PCR{sub L}/PCR{sub V} with a sweep direction perpendicular to motion direction showed large hot/cold spots; however, this effect vanished with higher numbers of rescannings for both methods. Similar observations were obtained for the other dose metrics, such as target motion (SI/AP), amplitude (6-22 mm peak-to-peak) and respiratory period (3.0-5.0 s). For four or more rescannings, both methods showed significantly better results, albeit that volumetric PCR was more affected by interference effects, which lead to severe degradation of a few dose distributions. The clinical example showed the same tendencies as the phantom study. Dose assessment metrics (D95, Dmax/Dmin, homogeneity index) were improved with an increasing number of PCR{sub L}/PCR{sub V}, but with PCR{sub L} being more robust. Conclusions: PCR{sub L} requires a longer treatment time than PCR{sub V} for high numbers of rescannings in the NIRS scanning system but is more robust. Although four or more rescans provided good dose homogeneity and conformity, the authors prefer to use more rescannings for clinical cases to further minimize dose degradation effects due to organ motion.

  11. Dosimetric consequences of inter-fraction breathing-pattern variation on radiotherapy with personalized motion-assessed margins

    Science.gov (United States)

    Kavanagh, A.; McQuaid, D.; Evans, P.; Webb, S.; Guckenberger, M.

    2011-11-01

    The data from eight patients who had undergone stereotactic body radiotherapy were selected due to their 4D-CT planning scans showing that their tumours had respiratory induced motion trajectories of large amplitude (greater than 9 mm in cranio-caudal direction). Radiotherapy plans with personalized motion-assessed margins were generated for these eight patients. The margins were generated by inverse 4D planning on an eight-bin phase-sorted 4D-CT scan. The planning was done on an in-house software system with a non-rigid registration stage being completed using freely available software. The resultant plans were then recalculated on a 4D-CT scan taken later during the course of treatment. Simulated image-guided patient set-up was used to align the geometric centres of the tumour region and minimize any misalignment between the two reconstructions. In general, the variation in the patient breathing patterns was found to be very small. Consequently, the degradation of the mean dose to the tumour region was found to be around a few percent (<3%) and hence was not a large effect.

  12. Self-dual variables, positive-semidefinite action, and discrete transformations in four-dimensional quantum gravity

    International Nuclear Information System (INIS)

    A positive-semidefinite Euclidean action for arbitrary four-topologies can be constructed by adding appropriate Yang-Mills and topological terms to the Samuel-Jacobson-Smolin action of gravity with (anti-)self-dual variables. Moreover, on shell, the (anti-)self-dual sector of the new theory corresponds precisely to all Einstein manifolds in four dimensions. The Lorentzian signature action and its analytic continuations are also considered. A self-contained discussion is given on the effects of discrete transformations C, P, and T on the Samuel-Jacobson-Smolin action, and other proposed actions which utilize self- or anti-self-dual variables as fundamental variables in the description of four-dimensional gravity

  13. Four-dimensional symmetry from a broad viewpoint. II Invariant distribution of quantized field oscillators and questions on infinities

    Science.gov (United States)

    Hsu, J. P.

    1983-01-01

    The foundation of the quantum field theory is changed by introducing a new universal probability principle into field operators: one single inherent and invariant probability distribution P(/k/) is postulated for boson and fermion field oscillators. This can be accomplished only when one treats the four-dimensional symmetry from a broad viewpoint. Special relativity is too restrictive to allow such a universal probability principle. A radical length, R, appears in physics through the probability distribution P(/k/). The force between two point particles vanishes when their relative distance tends to zero. This appears to be a general property for all forces and resembles the property of asymptotic freedom. The usual infinities in vacuum fluctuations and in local interactions, however complicated they may be, are all removed from quantum field theories. In appendix A a simple finite and unitary theory of unified electroweak interactions is discussed without assuming Higgs scalar bosons.

  14. Adjoint free four-dimensional variational data assimilation for a storm surge model of the German North Sea

    Science.gov (United States)

    Zheng, Xiangyang; Mayerle, Roberto; Xing, Qianguo; Fernández Jaramillo, José Manuel

    2016-06-01

    In this paper, a data assimilation scheme based on the adjoint free Four-Dimensional Variational(4DVar) method is applied to an existing storm surge model of the German North Sea. To avoid the need of an adjoint model, an ensemble-like method to explicitly represent the linear tangent equation is adopted. Results of twin experiments have shown that the method is able to recover the contaminated low dimension model parameters to their true values. The data assimilation scheme was applied to a severe storm surge event which occurred in the North Sea in December 5, 2013. By adjusting wind drag coefficient, the predictive ability of the model increased significantly. Preliminary experiments have shown that an increase in the predictive ability is attained by narrowing the data assimilation time window.

  15. Testing a four-dimensional variational data assimilation method using an improved intermediate coupled model for ENSO analysis and prediction

    Science.gov (United States)

    Gao, Chuan; Wu, Xinrong; Zhang, Rong-Hua

    2016-07-01

    A four-dimensional variational (4D-Var) data assimilation method is implemented in an improved intermediate coupled model (ICM) of the tropical Pacific. A twin experiment is designed to evaluate the impact of the 4D-Var data assimilation algorithm on ENSO analysis and prediction based on the ICM. The model error is assumed to arise only from the parameter uncertainty. The "observation" of the SST anomaly, which is sampled from a "truth" model simulation that takes default parameter values and has Gaussian noise added, is directly assimilated into the assimilation model with its parameters set erroneously. Results show that 4D-Var effectively reduces the error of ENSO analysis and therefore improves the prediction skill of ENSO events compared with the non-assimilation case. These results provide a promising way for the ICM to achieve better real-time ENSO prediction.

  16. Development of an ultra-high-speed scanning neutron tomography system for high-quality and four-dimensional visualizations

    International Nuclear Information System (INIS)

    A new neutron tomography imaging system was developed in order to realize high-quality three-dimensional (3D) and four-dimensional (4D) visualizations by fusing the high-frame-rate neutron radiography and computed tomography (CT) techniques. The fundamental idea is that the object is revolved with high rotating speed and the neutron radiography images are recorded with a high-speed video camera and an image intensifier, and then the consecutive images are processed by a 3D CT technique. The 4D dynamic images of the sand flow in the sandglasses could be visualized clearly. This new technique has also an advantage in that it can reduce radio-activation of the object materials remarkably.

  17. Investigation of four-dimensional computed tomography-based pulmonary ventilation imaging in patients with emphysematous lung regions

    Science.gov (United States)

    Yamamoto, Tokihiro; Kabus, Sven; Klinder, Tobias; Lorenz, Cristian; von Berg, Jens; Blaffert, Thomas; Loo, Billy W., Jr.; Keall, Paul J.

    2011-04-01

    A pulmonary ventilation imaging technique based on four-dimensional (4D) computed tomography (CT) has advantages over existing techniques. However, physiologically accurate 4D-CT ventilation imaging has not been achieved in patients. The purpose of this study was to evaluate 4D-CT ventilation imaging by correlating ventilation with emphysema. Emphysematous lung regions are less ventilated and can be used as surrogates for low ventilation. We tested the hypothesis: 4D-CT ventilation in emphysematous lung regions is significantly lower than in non-emphysematous regions. Four-dimensional CT ventilation images were created for 12 patients with emphysematous lung regions as observed on CT, using a total of four combinations of two deformable image registration (DIR) algorithms: surface-based (DIRsur) and volumetric (DIRvol), and two metrics: Hounsfield unit (HU) change (VHU) and Jacobian determinant of deformation (VJac), yielding four ventilation image sets per patient. Emphysematous lung regions were detected by density masking. We tested our hypothesis using the one-tailed t-test. Visually, different DIR algorithms and metrics yielded spatially variant 4D-CT ventilation images. The mean ventilation values in emphysematous lung regions were consistently lower than in non-emphysematous regions for all the combinations of DIR algorithms and metrics. VHU resulted in statistically significant differences for both DIRsur (0.14 ± 0.14 versus 0.29 ± 0.16, p = 0.01) and DIRvol (0.13 ± 0.13 versus 0.27 ± 0.15, p ventilation and emphysema, which indicates the potential for HU-based 4D-CT ventilation imaging to achieve high physiologic accuracy. A further study is needed to confirm these results.

  18. Swallowing assessment in early laryngeal cancer patients treated either with surgery or radiotherapy

    International Nuclear Information System (INIS)

    Swallowing is a complex neuromuscular process that requires anatomical indemnity and an adequate coordination of several organs. Laryngeal cancer treatment may cause swallowing disorders. Traditionally, a high frequency of this type of disorder after surgery has been reported, but no actual data concerning its incidence in patients undergoing radiotherapy for early laryngeal cancer has been published. Aim. To compare swallowing disorders frequency posterior to treatment in early laryngeal cancer patients. Material and Method. Two groups of early laryngeal cancer patients were transversally studied, one treated with vertical partial surgery (CP), and the other treated exclusively with radiotherapy. Each patient had otorhinolaryngological, nasofibroscopic and video fluoroscopic evaluations after treatment. Differences between groups were compared using the -square test. Results. Twenty patients per group were entered in this study, predominantly males of similar age. Both groups presented a high incidence of aspiration symptoms (55% in RT and 35% in CP). There were no significant differences between both groups. Discussion and Conclusion. A high incidence of swallowing disorders in patients treated for early laryngeal cancer was found. It should then be considered as a frequent alteration in this group of patients, either treated with RT or CP

  19. A SEGMENTATION PROBLEM IN QUANTITATIVE ASSESSMENT OF ORGAN DISPOSITION IN RADIOTHERAPY

    Directory of Open Access Journals (Sweden)

    Giovanni Naldi

    2011-11-01

    Full Text Available Radiotherapeutic treatment of cancer is best conducted if the prescription dose is given to the tumor while surrounding normal tissues are maximally spared. With the aim to meet these requirements the complexity of radiotherapy techniques have steadily increased under a strong technological impulse, especially in the last decades. One problem involves the rate of the particular disposition of the structures of interest in a patient. Recently the authors (Tomatis et al., 2010; 2011 have proposed a computational approach in order to represent quantitatively the geometrical features of organs at risk, summarized in characteristics of distance, shape and orientation of such organs in respect to the target. A basic problem to solve before to compute the risk index, is the segmentation of the organs involved in the radiotherapy planning. Here we described a 3D segmentation method by using the clinical computed tomography (CT data of the patients. Our algorithm is based on different steps, a preprocessing phase where a nonlinear diffusion filter is applied; a level set based method for extract 2D countours; a postprocessing reconstruction of 3D volume from 2D segmented slices. Some comparisons with manually traced segmentation by clinical experts are provided.

  20. Patient assessed symptoms are poor predictors of objective findings. Results from a cross sectional study in patients treated with radiotherapy for pharyngeal cancer

    DEFF Research Database (Denmark)

    Jensen, Kenneth; Lambertsen, Karin; Torkov, Peter;

    2007-01-01

    Introduction. The aim of the study was to assess the value of the EORTC questionnaires C30 and H&N35, as an instrument for the study of side effects. Patients and methods. We invited all recurrence free patients, treated with radical radiotherapy for pharyngeal cancer between 1998 and 2002 at our...

  1. Imaging of normal lung, liver and parotid gland function for radiotherapy

    International Nuclear Information System (INIS)

    There is growing clinical evidence that functional imaging is useful for target volume definition and early assessment of tumour response to external beam radiotherapy. A subject that has perhaps received less attention, but is no less promising, is the application of functional imaging to the prediction or measurement of radiation adverse effects in normal tissues. In this manuscript, we review the current published literature describing the use of positron emission tomography (PET), four-dimensional computed tomography (4D-CT), single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) to study normal tissue function in the context of radiotherapy to the lung, liver and head and neck. Published results to date demonstrate that functional imaging can be used to preferentially avoid normal tissues not easily identifiable on solely anatomical images. It is also a potentially very powerful tool for the early detection of radiotherapy-induced normal tissue adverse effects and could provide valuable data for building predictive models of outcome. However, one of the major challenges to building useful predictive models is that, to date, there are very little data available with combined images of normal function, 3D delivered radiation dose and clinical outcomes. Prospective data collection through well-constructed studies which use established morbidity scores is clearly a priority if significant progress is to be made in this area.

  2. Impaired DNA repair as assessed by the ''comet'' assay in patients developing thyroid carcinoma after radiotherapy

    International Nuclear Information System (INIS)

    A defective cellular response to DNA lesions induced be genotoxic agents may be associated to an increased cancer proneness. This has been clearly identified in some rare but extensively studied genetic diseases such as xeroderma pigmentosum (XP), ataxia telangiectasia (AT) and Fanconi anemia (FA). In practical oncology, most patients receive genotoxic therapeutic agents and the presence of so far unidentified sensitive genotypes could account for an increased susceptibility to cancer in a subgroup of exposed patients. The thyroid gland of children is especially sensitive to the carcinogenic effect of ionizing radiation. Evidence for risk is reported even at doses as low as 0.1 Gy, and the excess relative risk to develop a thyroid tumor following a radiation dose of 1 Gy in childhood is of 7.7 [l]. In order to determine if a defect in repair of DNA strand breaks could be involved, as an early step, in the development of secondary thyroid tumors after radiotherapy, we examined, using the alkaline single cell gel electrophoresis assay (SCGE or 'comet'), the response to in vitro γ-rays exposure of lymphocytes of a small group of patients who developed thyroid carcinoma after radiotherapy for a primary tumor. Because of its practical advantages, the alkaline comet assay offers the opportunity to question the role of DNA strand beaks rejoining capacity of the individual in the radiation induced carcinogenesis of thyroid tumors. This preliminary study of a small group of patients with therapeutic irradiation at childhood for a primary tumor indicates that, at the time of blood sampling, lymphocytes of some of these patients demonstrated reduced rejoining capacity. These results suggest that the comet assay might help to distinguish a subgroup of individuals at risk for radiation induced genomic instability and encourage further investigation. (authors)

  3. SU-E-J-171: Surface Imaging Based Intrafraction Motion Assessments for Whole Brain Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To quantify and characterize intrafraction motion for whole brain radiotherapy treatments in open face masks using 3D surface imaging. Methods: Fifteen whole brain patients were monitored with 3D surface imaging over a total of 202 monitoring sessions. Mean translations and rotations were calculated over each minute, each session, and over all sessions combined. The percentage of each session that the root mean square (RMS) of the linear translations were outside of 2 mm, 3 mm, 4 mm, and 5 mm were determined for each patient. Correlations between mean translations per minute and time and between standard deviation per minute and time were evaluated using Pearson's r value. Results: The mean RMS translation averaged over all patients was 1.45 mm +/− 1.52 mm. The patients spent an average of 18%, 10%, 6%, and 3% of the monitoring time outside of 2 mm, 3 mm, 4 mm, and 5 mm RMS tolerances, respectively. The RMS values averaged over all patients were 1.31 mm +/− 0.98 mm, 1.52 +/- 1.04, and 1.30 mm +/− 0.71 mm over the 1th, 5th, and 10th minutes of monitoring, respectively. Neither, the RMS values (p = 0.15) or the standard deviations of the RMS values (p = 0.16) showed significant correlations with time. Conclusion: The patients were positioned within 2 mm of isocenter, which was the initial set-up tolerance, for the majority of their treatments. The average position changed by < 0.3 mm over 10 minutes of monitoring. Short term movements, reflected by the standard deviations, where on the order of 1 mm. This immobilization system provides adequate immobilization over a course of treatment for whole brain radiotherapy. This system may also be suitable for head and neck or stereotactic radiosurgery treatments as well

  4. Assessment of pulmonary toxicities in breast cancer patients undergoing treatment with anthracycline and taxane based chemotherapy and radiotherapy- a prospective study

    Directory of Open Access Journals (Sweden)

    Aramita Saha

    2013-12-01

    Full Text Available Background: Anthracycline based regiments and/or taxanes and adjuvant radiotherapy; the main modalities of treatment for breast cancers are associated with deterioration of pulmonary functions and progressive pulmonary toxicities. Aim: Assessment of pulmonary toxicities and impact on pulmonary functions mainly in terms of decline of forced vital capacity (FVC and the ratio of forced expiratory volume (FEV in 1 Second and FEV1/FVC ratio with different treatment times and follow ups in carcinoma breast patients receiving anthracycline and/or taxane based chemotherapy and radiotherapy. Materials and methods: A prospective single institutional cohort study was performed with 58 breast cancer patients between January 2011 to July 2012 who received either anthracycline based (37 patients received 6 cycles FAC= 5 FU, Adriamycin, Cyclophosphamide regime and radiotherapy or anthracycline and taxane based chemotherapy (21 patients received 4cycles AC= Adriamycin, Cyclophosphamide; followed by 4 cycles of T=Taxane and radiotherapy. Assessment of pulmonary symptoms and signs, chest x-ray and pulmonary function tests were performed at baseline, midcycle, at end of chemotherapy, at end radiotherapy, at 1 and 6 months follow ups and compared. By means of a two-way analysis of variance (ANOVA model, the course of lung parameters across the time points was compared. Results and Conclusion: Analysis of mean forced vital capacities at different points of study times showed definitive declining pattern, which is at statistically significant level at the end of 6th month of follow up (p=0.032 .The FEV1/FVC ratio (in percentage also revealed a definite decreasing pattern over different treatment times and at statistically significant level at 6th month follow up with p value 0.003. Separate analysis of mean FEV1/FVC ratios over time in anthracycline based chemotherapy and radiotherapy group as well as anthracycline and taxane based chemotherapy and radiotherapy group

  5. Investigation of four-dimensional computed tomography-based pulmonary ventilation imaging in patients with emphysematous lung regions

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Tokihiro; Loo, Billy W Jr; Keall, Paul J [Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Dr, Stanford, CA 94305-5847 (United States); Kabus, Sven; Lorenz, Cristian; Von Berg, Jens; Blaffert, Thomas [Department of Digital Imaging, Philips Research Europe, Roentgenstrasse 24-26, D-22335 Hamburg (Germany); Klinder, Tobias, E-mail: Tokihiro@stanford.edu [Clinical Informatics, Interventional, and Translational Solutions, Philips Research North America, Briarcliff Manor, NY 10510 (United States)

    2011-04-07

    A pulmonary ventilation imaging technique based on four-dimensional (4D) computed tomography (CT) has advantages over existing techniques. However, physiologically accurate 4D-CT ventilation imaging has not been achieved in patients. The purpose of this study was to evaluate 4D-CT ventilation imaging by correlating ventilation with emphysema. Emphysematous lung regions are less ventilated and can be used as surrogates for low ventilation. We tested the hypothesis: 4D-CT ventilation in emphysematous lung regions is significantly lower than in non-emphysematous regions. Four-dimensional CT ventilation images were created for 12 patients with emphysematous lung regions as observed on CT, using a total of four combinations of two deformable image registration (DIR) algorithms: surface-based (DIR{sup sur}) and volumetric (DIR{sup vol}), and two metrics: Hounsfield unit (HU) change (V{sub HU}) and Jacobian determinant of deformation (V{sub Jac}), yielding four ventilation image sets per patient. Emphysematous lung regions were detected by density masking. We tested our hypothesis using the one-tailed t-test. Visually, different DIR algorithms and metrics yielded spatially variant 4D-CT ventilation images. The mean ventilation values in emphysematous lung regions were consistently lower than in non-emphysematous regions for all the combinations of DIR algorithms and metrics. V{sub HU} resulted in statistically significant differences for both DIR{sup sur} (0.14 {+-} 0.14 versus 0.29 {+-} 0.16, p = 0.01) and DIR{sup vol} (0.13 {+-} 0.13 versus 0.27 {+-} 0.15, p < 0.01). However, V{sub Jac} resulted in non-significant differences for both DIR{sup sur} (0.15 {+-} 0.07 versus 0.17 {+-} 0.08, p = 0.20) and DIR{sup vol} (0.17 {+-} 0.08 versus 0.19 {+-} 0.09, p = 0.30). This study demonstrated the strong correlation between the HU-based 4D-CT ventilation and emphysema, which indicates the potential for HU-based 4D-CT ventilation imaging to achieve high physiologic accuracy. A

  6. Investigation of four-dimensional computed tomography-based pulmonary ventilation imaging in patients with emphysematous lung regions

    International Nuclear Information System (INIS)

    A pulmonary ventilation imaging technique based on four-dimensional (4D) computed tomography (CT) has advantages over existing techniques. However, physiologically accurate 4D-CT ventilation imaging has not been achieved in patients. The purpose of this study was to evaluate 4D-CT ventilation imaging by correlating ventilation with emphysema. Emphysematous lung regions are less ventilated and can be used as surrogates for low ventilation. We tested the hypothesis: 4D-CT ventilation in emphysematous lung regions is significantly lower than in non-emphysematous regions. Four-dimensional CT ventilation images were created for 12 patients with emphysematous lung regions as observed on CT, using a total of four combinations of two deformable image registration (DIR) algorithms: surface-based (DIRsur) and volumetric (DIRvol), and two metrics: Hounsfield unit (HU) change (VHU) and Jacobian determinant of deformation (VJac), yielding four ventilation image sets per patient. Emphysematous lung regions were detected by density masking. We tested our hypothesis using the one-tailed t-test. Visually, different DIR algorithms and metrics yielded spatially variant 4D-CT ventilation images. The mean ventilation values in emphysematous lung regions were consistently lower than in non-emphysematous regions for all the combinations of DIR algorithms and metrics. VHU resulted in statistically significant differences for both DIRsur (0.14 ± 0.14 versus 0.29 ± 0.16, p = 0.01) and DIRvol (0.13 ± 0.13 versus 0.27 ± 0.15, p Jac resulted in non-significant differences for both DIRsur (0.15 ± 0.07 versus 0.17 ± 0.08, p = 0.20) and DIRvol (0.17 ± 0.08 versus 0.19 ± 0.09, p = 0.30). This study demonstrated the strong correlation between the HU-based 4D-CT ventilation and emphysema, which indicates the potential for HU-based 4D-CT ventilation imaging to achieve high physiologic accuracy. A further study is needed to confirm these results.

  7. Artifacts in conventional computed tomography (CT) and free breathing four-dimensional CT induce uncertainty in gross tumor volume determination

    DEFF Research Database (Denmark)

    Persson, Gitte Fredberg; Nygaard, Ditte Eklund; Munck af Rosenschöld, Per;

    2011-01-01

    compare delineated gross tumor volume (GTV) sizes in 3DCT, 4DCT, and BHCT scans of patients with lung tumors. Methods and Materials A total of 36 patients with 46 tumors referred for stereotactic radiotherapy of lung tumors were included. All patients underwent positron emission tomography (PET)/CT, 4DCT......Purpose Artifacts impacting the imaged tumor volume can be seen in conventional three-dimensional CT (3DCT) scans for planning of lung cancer radiotherapy but can be reduced with the use of respiration-correlated imaging, i.e., 4DCT or breathhold CT (BHCT) scans. The aim of this study was to......, and BHCT scans. GTVs in all CT scans of individual patients were delineated during one session by a single physician to minimize systematic delineation uncertainty. The GTV size from the BHCT was considered the closest to true tumor volume and was chosen as the reference. The reference GTV size was...

  8. Four-dimensional variational data assimilation for inverse modelling of atmospheric methane emissions: method and comparison with synthesis inversion

    Directory of Open Access Journals (Sweden)

    J. F. Meirink

    2008-11-01

    Full Text Available A four-dimensional variational (4D-Var data assimilation system for inverse modelling of atmospheric methane emissions is presented. The system is based on the TM5 atmospheric transport model. It can be used for assimilating large volumes of measurements, in particular satellite observations and quasi-continuous in-situ observations, and at the same time it enables the optimization of a large number of model parameters, specifically grid-scale emission rates. Furthermore, the variational method allows to estimate uncertainties in posterior emissions. Here, the system is applied to optimize monthly methane emissions over a 1-year time window on the basis of surface observations from the NOAA-ESRL network. The results are rigorously compared with an analogous inversion by Bergamaschi et al. (2007, which was based on the traditional synthesis approach. The posterior emissions as well as their uncertainties obtained in both inversions show a high degree of consistency. At the same time we illustrate the advantage of 4D-Var in reducing aggregation errors by optimizing emissions at the grid scale of the transport model. The full potential of the assimilation system is exploited in Meirink et al. (2008, who use satellite observations of column-averaged methane mixing ratios to optimize emissions at high spatial resolution, taking advantage of the zooming capability of the TM5 model.

  9. Restoration of four-dimensional diffeomorphism covariance in canonical general relativity: An intrinsic Hamilton-Jacobi approach

    Science.gov (United States)

    Salisbury, Donald; Renn, Jürgen; Sundermeyer, Kurt

    2016-02-01

    Classical background independence is reflected in Lagrangian general relativity through covariance under the full diffeomorphism group. We show how this independence can be maintained in a Hamilton-Jacobi approach that does not accord special privilege to any geometric structure. Intrinsic space-time curvature-based coordinates grant equal status to all geometric backgrounds. They play an essential role as a starting point for inequivalent semiclassical quantizations. The scheme calls into question Wheeler’s geometrodynamical approach and the associated Wheeler-DeWitt equation in which 3-metrics are featured geometrical objects. The formalism deals with variables that are manifestly invariant under the full diffeomorphism group. Yet, perhaps paradoxically, the liberty in selecting intrinsic coordinates is precisely as broad as is the original diffeomorphism freedom. We show how various ideas from the past five decades concerning the true degrees of freedom of general relativity can be interpreted in light of this new constrained Hamiltonian description. In particular, we show how the Kuchař multi-fingered time approach can be understood as a means of introducing full four-dimensional diffeomorphism invariants. Every choice of new phase space variables yields new Einstein-Hamilton-Jacobi constraining relations, and corresponding intrinsic Schrödinger equations. We show how to implement this freedom by canonical transformation of the intrinsic Hamiltonian. We also reinterpret and rectify significant work by Dittrich on the construction of “Dirac observables.”

  10. The finite-size scaling study of four-dimensional Ising model in the presence of external magnetic field

    International Nuclear Information System (INIS)

    The four-dimensional ferromagnetic Ising model in external magnetic field is simulated on the Creutz cellular automaton algorithm using finite-size lattices with linear dimension 4 <= L <= 8. The critical temperature value of infinite lattice, Tcchi (∞) approx 6.680(1) obtained for h = 0 agrees well with the values Tc (infinity) approx 6.68 obtained previously using different methods. Moreover, h = 0.00025 in our work also agrees with all the results obtained from h = 0 in the literature. However, there are no works for h not= 0 in the literature. The value of the field critical exponent (δ = 3.0136(3)) is in good agreement with δ = 3 which is obtained from scaling law of Widom. In spite of the finite-size scaling relations of IML(t)| and χL(t) for 0 <= h <= 0.001 are verified; however, in the cases of 0.0025 <= h <= 0.1 they are not verified

  11. Direct construction of a four-dimensional mesh model from a three-dimensional object with continuous rigid body movement

    Directory of Open Access Journals (Sweden)

    Ikuru Otomo

    2014-04-01

    Full Text Available In the field of design and manufacturing, there are many problems with managing dynamic states of three-dimensional (3D objects. In order to solve these problems, the four-dimensional (4D mesh model and its modeling system have been proposed. The 4D mesh model is defined as a 4D object model that is bounded by tetrahedral cells, and can represent spatio-temporal changes of a 3D object continuously. The 4D mesh model helps to solve dynamic problems of 3D models as geometric problems. However, the construction of the 4D mesh model is limited on the time-series 3D voxel data based method. This method is memory-hogging and requires much computing time. In this research, we propose a new method of constructing the 4D mesh model that derives from the 3D mesh model with continuous rigid body movement. This method is realized by making a swept shape of a 3D mesh model in the fourth dimension and its tetrahe-dralization. Here, the rigid body movement is a screwed movement, which is a combination of translational and rotational movement.

  12. Four-dimensional cardiac reconstruction from rotational x-ray sequences: first results for 4D coronary angiography

    Science.gov (United States)

    Hansis, Eberhard; Schomberg, Hermann; Erhard, Klaus; Dössel, Olaf; Grass, Michael

    2009-02-01

    The tomographic reconstruction of the beating heart requires dedicated methods. One possibility is gated reconstruction, where only data corresponding to a certain motion state are incorporated. Another one is motioncompensated reconstruction with a pre-computed motion vector field, which requires a preceding estimation of the motion. Here, results of a new approach are presented: simultaneous reconstruction of a three-dimensional object and its motion over time, yielding a fully four-dimensional representation. The object motion is modeled by a time-dependent elastic transformation. The reconstruction is carried out with an iterative gradient-descent algorithm which simultaneously optimizes the three-dimensional image and the motion parameters. The method was tested on a simulated rotational X-ray acquisition of a dynamic coronary artery phantom, acquired on a C-arm system with a slowly rotating C-arm. Accurate reconstruction of both absorption coefficient and motion could be achieved. First results from experiments on clinical rotational X-ray coronary angiography data are shown. The resulting reconstructions enable the analysis of both static properties, such as vessel geometry and cross-sectional areas, and dynamic properties, like magnitude, speed, and synchrony of motion during the cardiac cycle.

  13. Four-dimensional Cone Beam CT Reconstruction and Enhancement using a Temporal Non-Local Means Method

    CERN Document Server

    Jia, Xun; Lou, Yifei; Sonke, Jan-Jakob; Jiang, Steve B

    2012-01-01

    Four-dimensional Cone Beam Computed Tomography (4D-CBCT) has been developed to provide respiratory phase resolved volumetric imaging in image guided radiation therapy (IGRT). Inadequate number of projections in each phase bin results in low quality 4D-CBCT images with obvious streaking artifacts. In this work, we propose two novel 4D-CBCT algorithms: an iterative reconstruction algorithm and an enhancement algorithm, utilizing a temporal nonlocal means (TNLM) method. We define a TNLM energy term for a given set of 4D-CBCT images. Minimization of this term favors those 4D-CBCT images such that any anatomical features at one spatial point at one phase can be found in a nearby spatial point at neighboring phases. 4D-CBCT reconstruction is achieved by minimizing a total energy containing a data fidelity term and the TNLM energy term. As for the image enhancement, 4D-CBCT images generated by the FDK algorithm are enhanced by minimizing the TNLM function while keeping the enhanced images close to the FDK results. A...

  14. An Alternative View of the Universe Structure (on the invalidity of the four dimensional space-time concept)

    CERN Document Server

    Hovsepian, Felix

    2007-01-01

    The model of the Universe in this paper uses equations of the unperturbed Keplerian motion. They have been updated, complementied and generalized when the solution of these equations is the characteristic function of a random value from the theory of probabilities. Argument of the differential equation in this case is any more time, an interval of time between sections of a random stationary prosess. In this paper this time interval is referred to as flexible (elastic) time due to its many non-trivial properties. It is proved flexible time does not depend on the space which makes invalid the four dimensional space-time concept. The Universe becomes stationary and Eucledian. It is proved: 1. the advavce of Mercury's perihelion versus the predictions in accordance with the universal gravity law results inequality of the coefficients in the correlation equations of Keplerian moution along axes x, y and z; 2. the velocity of propagation of harmonic oscillation in the Uneverse is not constant; 3. long-range intera...

  15. The "universal property" of Horizon Entropy Sum of Black Holes in Four Dimensional Asymptotical (anti-)de-Sitter Spacetime Background

    CERN Document Server

    Wang, Jia; Meng, Xin-he

    2014-01-01

    We present a new universal property of entropy, that is the entropy sum relation of black holes in four dimensional (anti-)de-Sitter asymptotical back- ground. They depend only on the cosmological constant with the necessary e?ect of the un-physical virtual horizon included in the spacetime where only the cosmological constant, mass of black hole, rotation parameter and Maxwell ?eld exist. When there is more extra matter ?eld in the spacetime, one will ?nd the entropy sum is also dependent of the strength of these extra matter ?eld. For both cases, we conclude that the entropy sum does not depend on the con- versed charges M, Q and J, while it does depend on the property of background spacetime. We will mainly test the entropy sum relation in static, stationary black hole and some black hole with extra matter source (scalar hair and higher curvature) in the asymptotical (anti-)de-sitter spacetime background. Besides, we point out a newly found counter example of the mass independence of the "entropy product" ...

  16. The Prognostic Value of a Four-Dimensional CT Angiography-Based Collateral Grading Scale for Reperfusion Therapy in Acute Ischemic Stroke Patients

    Science.gov (United States)

    Zhang, Sheng; Chen, Weili; Tang, Huan; Han, Quan; Yan, Shenqiang; Zhang, Xiaocheng; Chen, Qingmeng; Parsons, Mark; Wang, Shaoshi; Lou, Min

    2016-01-01

    Objective Leptomeningeal collaterals, which affects tissue fate, are still challenging to assess. Four-dimensional CT angiography (4D CTA) originated from CT perfusion (CTP) provides the possibility of non-invasive and time-resolved assessment of leptomeningeal collateral flow. We sought to develop a comprehensive rating system to integrate the speed and extent of collateral flow on 4D CTA, and investigate its prognostic value for reperfusion therapy in acute ischemic stroke (AIS) patients. Methods We retrospectively studied 80 patients with M1 ± internal carotid artery (ICA) occlusion who had baseline CTP before intravenous thrombolysis. The velocity and extent of collaterals were evaluated by regional leptomeningeal collateral score on peak phase (rLMC-P) and temporally fused intensity projections (tMIP) (rLMC-M) on 4D CTA, respectively. The cutoffs of rLMC-P and rLMC-M score for predicting good outcome (mRS score ≤ 2) were integrated to develop the collateral grading scale (CGS) (rating from 0–2). Results The CGS score was correlated with 3-months mRS score (non-recanalizers: ρ = -0.495, p = 0.01; recanalizers: ρ = -0.671, p < 0.001). Patients with intermediate or good collaterals (CGS score of 1 and 2) who recanalized were more likely to have good outcome than those without recanalization (p = 0.038, p = 0.018), while there was no significant difference in outcome in patients with poor collaterals (CGS score of 0) stratified by recanalization (p = 0.227). Conclusions Identification of collaterals based on CGS may help to select good responders to reperfusion therapy in patients with large artery occlusion. PMID:27505435

  17. Assessing cumulative dose distributions in combined radiotherapy for cervical cancer using deformable image registration with pre-imaging preparations

    International Nuclear Information System (INIS)

    The purpose of the study was to evaluate the feasibility of deformable image registration (DIR) in assessing cumulative dose distributions of the combination of external beam radiotherapy (EBRT) and fractionated intracavitary brachytherapy (ICBT) for cervical cancer. Three-dimensional image data sets of five consecutive patients were used. The treatment plan consisted of whole pelvic EBRT (total dose: 45 Gy in 25 fractions) combined with computed tomography (CT)-based high-dose rate ICBT (≥24 Gy in 4 fractions to the high risk clinical target volume (HR-CTV)). Organs at risk and HR-CTV were contoured on each CT images and dose-volume parameters were acquired. Pre-imaging preparations were performed prior to each ICBT to minimize the uncertainty of the organ position. Physical doses of each treatment were converted to biologically equivalent doses in 2 Gy daily fractions by the linear quadratic model. Three-dimensional dose distributions of each treatment were accumulated on CT images of the first ICBT using DIR with commercially available image registration software (MIM Maestro®). To compare with DIR, 3D dose distributions were fused by rigid registration based on bony structure matching. To evaluate the accuracy of DIR, the Dice similarity coefficient (DSC) was measured between deformed contours and initial contours. The cumulative dose distributions were successfully illustrated on the CT images using DIR. Mean DSCs of the HR-CTV, rectum, and bladder were 0.46, 0.62 and 0.69, respectively, with rigid registration; and 0.78, 0.76, and 0.87, respectively, with DIR (p <0.05). The mean DSCs derived from our DIR procedure were comparable to those of previous reports describing the quality of DIR algorithms in the pelvic region. DVH parameters derived from the 2 methods showed no significant difference. Our results suggest that DIR-based dose accumulation may be acceptable for assessing cumulative dose distributions to assess doses to the tumor and organs at risk

  18. Measurement of the transverse four-dimensional beam rms-emittance of an intense uranium beam at 11.4 MeV/u

    Science.gov (United States)

    Xiao, C.; Groening, L.; Gerhard, P.; Maier, M.; Mickat, S.; Vormann, H.

    2016-06-01

    Knowledge of the transverse four-dimensional beam rms-parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Usually pepper-pots are used for measuring these beam parameters. However, for ions their application is limited to energies below 150 keV/u. This contribution is on measurements of the full transverse four-dimensional second-moments beam matrix of high intensity uranium ions at an energy of 11.4 MeV/u. The combination of skew quadrupoles with a slit/grid emittance measurement device has been successfully applied.

  19. Longitudinal Assessments of Quality of Life in Endometrial Cancer Patients: Effect of Surgical Approach and Adjuvant Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: Adjuvant radiotherapy (RT) is often considered for endometrial cancer. We studied the effect of RT and surgical treatment on patients' quality of life (QOL). Methods and Materials: All patients referred to the gynecologic oncology clinics with biopsy findings showing endometrial cancer were recruited. QOL assessments were performed using the European Organization for Research and Treatment of Cancer QOL questionnaire-C30, version 3. Assessments were obtained at study entry and at regular 3-month intervals for a maximum of 2 years. Open-ended telephone interviews were done every 6 months. Linear mixed regression models were built using QOL domain scores as dependent variables, with the predictors of surgical treatment and adjuvant RT type. Results: A total of 40 patients were recruited; 80% of the surgeries were performed by laparotomy. Significant improvements were seen in most QOL domains with increased time from treatment. Adjuvant RT resulted in significantly more severe bowel symptoms and improvement in insomnia compared with conservative follow-up. No significant adverse effect from adjuvant RT was seen on the overall QOL. Bowel symptoms were significantly increased in patients treated with laparotomy compared with laparoscopy in the patients treated with whole pelvic RT. Qualitatively, about one-half of the patients noted improvements in their overall QOL during follow-up, with easy fatigability the most prevalent. Conclusion: No significant adverse effect was seen on patients' overall QOL with adjuvant pelvic RT after the recovery period. The acute adverse effects on patients' QOL significantly improved with an increasing interval from diagnosis.

  20. Safety assessment of molecular targeted therapies in association with radiotherapy in metastatic renal cell carcinoma: a real-life report.

    Science.gov (United States)

    Langrand-Escure, Julien; Vallard, Alexis; Rivoirard, Romain; Méry, Benoîte; Guy, Jean-Baptiste; Espenel, Sophie; Trone, Jane-Chloé; Ben Mrad, Majed; Diao, Peng; Rancoule, Chloé; Suchaud, Jean-Philippe; Fournel, Pierre; Guillot, Aline; Chargari, Cyrus; Escudier, Bernard; Négrier, Sylvie; Magné, Nicolas

    2016-06-01

    Molecular targeted therapies (TT) are the cornerstone of metastatic renal cell carcinoma (RCC) treatment. There is a paucity of data on the safety of the radiotherapy (RT)-TT association in a sequential or a concomitant setting. The aim of the present study is to retrospectively assess the safety of the RT-TT association. From 2006 to 2014, data from 84 consecutive patients treated with RT and TT for metastatic RCC were retrospectively collected. RT-TT sequential and concomitant associations were, respectively, defined by a time interval of more than five TT half-lives and less than or equal to five TT half-lives between the last TT administration and RT initiation. Toxicities in the fields of RT were assessed systematically. As many patients received several TT and RT courses, 136 RT-TT associations were analyzed, with 66 sequential and 70 concomitant schemes. RT was mainly delivered on bone (75%) and brain metastases (14.7%). TT were tyrosine kinase inhibitors (73.5%), mTOR inhibitors (19.8%), and monoclonal antibodies (6.7%). With a median follow-up of 9.5 months, whatever the sequence, no grade≥4 toxicity was reported. Two grade 3 toxicities were reported with sequential (3%) and concomitant (2.9%) RT-TT, respectively. Sequential or concomitant RT-TT associations in metastatic RCC do not seem to cause major toxicity. PMID:27045782

  1. Quantitative dosimetric assessment for effect of gold nanoparticles as contrast media on radiotherapy planning

    International Nuclear Information System (INIS)

    In CT planning for radiation therapy, patients may be asked to have a medical procedure of contrast agent (CA) administration as required by their physicians. CA media improve quality of CT images and assist radiation oncologists in delineation of the target or organs with accuracy. However, dosimetric discrepancy may occur between scenarios in which CA media are present in CT planning and absent in treatment delivery. In recent preclinical experiments of small animals, gold nanoparticles (AuNPs) have been identified as an excellent contrast material of x-ray imaging. In this work, we quantitatively evaluate the effect of AuNPs to be used as a potential material of contrast enhancement in radiotherapy planning with an analytical phantom and clinical case. Conray 60, an iodine-based product for contrast enhancement in clinical uses, is included as a comparison. Other additional variables such as different concentrations of CA media, radiation delivery techniques and dose calculation algorithms are included. We consider 1-field AP, 4-field box, 7-field intensity modulated radiation therapy (IMRT) and a recent technique of volumetric modulated arc therapy (VMAT). CA media of AuNPs (Conray 60) with concentrations of 10%, 20%, 30%, 40% and 50% containing 28.2, 56.4, 84.6, 112.8 and 141.0 mg of gold (iodine) per mL were prepared prior to CT scanning. A virtual phantom with a target where nanoparticle media are loaded and clinical case of gastric lymphoma in which the Conray 60 media were given to the patient prior to the CT planning are included for the study. Compared to Conray 60 media with concentration of 10%/50%, Hounsfield units for AuNP media of 10%/50% are 322/1608 higher due to the fact that atomic number of Au (Z=79) is larger than I (Z=53). In consequence, dosimetric discrepancy of AuNPs is magnified between presence and absence of contrast media. It was found in the phantom study that percent dose differences between presence and absence of CA media may be

  2. Effects of radiation scatter exposure on electrometer dose assessment in orthovoltage radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Butson, Martin J., E-mail: martin.butson@sesiahs.health.nsw.gov.a [City University of Hong Kong, Dept. of Physics and Materials Science, Kowloon Tong (Hong Kong); Illawarra Cancer Care Centre, Department of Medical Physics, Crown St, Wollongong, N.S.W 2500 (Australia); Illawarra Health and Medical Research Institute and the Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave Gwynneville, N.S.W (Australia); Yu, Peter K.N.; Cheung, Tsang [City University of Hong Kong, Dept. of Physics and Materials Science, Kowloon Tong (Hong Kong); Oborn, B.M. [Illawarra Cancer Care Centre, Department of Medical Physics, Crown St, Wollongong, N.S.W 2500 (Australia); Illawarra Health and Medical Research Institute and the Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave Gwynneville, N.S.W (Australia)

    2011-04-15

    During orthovoltage x-ray radiotherapy dosimetry, normal practice requires the use of a standard ionisation chamber and dedicated electrometer for dosimetry. In ideal conditions, the electrometer is positioned outside the treatment room to eliminate any effects from scatter radiation on dose measurement. However in some older designed rooms, there is no access portal for the chamber cable to run to an 'outside' position for the electrometer. As such the electrometer is positioned within the treatment room. This work quantifies the effects on measured charge when this occurs. Results have shown that with the electrometer positioned next to a solid water dosimetry stack and using a large 15 x 15 cm field at 250 kVp x-ray beam energy, charge results can deviate by up to {+-}17.2% depending on the polarity applied to the chamber compared to readings when the electrometer is outside the treatment room. It is assumed to be due to scatter radiation producing electrons in the amplifying circuit of the electrometer. Results are also shown when the electrometer is shielded by a 4 mm thick lead casing whilst inside the room which removes the scattering effect, providing the best case scenario when the electrometer must remain in the treatment room. Whilst it is well known that an electrometer should not be irradiated (even to scattered radiation), often small kilovoltage or orthovoltage rooms do not have a portal access for an electrometer to go outside. As such it would be recommended for a lead shield to be placed around the electrometer during irradiation if this was to occur to minimize dosimetric inaccuracies which may occur due to scattered radiation effects.

  3. Effects of radiation scatter exposure on electrometer dose assessment in orthovoltage radiotherapy

    International Nuclear Information System (INIS)

    During orthovoltage x-ray radiotherapy dosimetry, normal practice requires the use of a standard ionisation chamber and dedicated electrometer for dosimetry. In ideal conditions, the electrometer is positioned outside the treatment room to eliminate any effects from scatter radiation on dose measurement. However in some older designed rooms, there is no access portal for the chamber cable to run to an 'outside' position for the electrometer. As such the electrometer is positioned within the treatment room. This work quantifies the effects on measured charge when this occurs. Results have shown that with the electrometer positioned next to a solid water dosimetry stack and using a large 15 x 15 cm field at 250 kVp x-ray beam energy, charge results can deviate by up to ±17.2% depending on the polarity applied to the chamber compared to readings when the electrometer is outside the treatment room. It is assumed to be due to scatter radiation producing electrons in the amplifying circuit of the electrometer. Results are also shown when the electrometer is shielded by a 4 mm thick lead casing whilst inside the room which removes the scattering effect, providing the best case scenario when the electrometer must remain in the treatment room. Whilst it is well known that an electrometer should not be irradiated (even to scattered radiation), often small kilovoltage or orthovoltage rooms do not have a portal access for an electrometer to go outside. As such it would be recommended for a lead shield to be placed around the electrometer during irradiation if this was to occur to minimize dosimetric inaccuracies which may occur due to scattered radiation effects.

  4. Unified registration framework for cumulative dose assessment in cervical cancer across external beam radiotherapy and brachytherapy

    Science.gov (United States)

    Roy, Sharmili; Totman, John J.; Choo, Bok A.

    2016-03-01

    Dose accumulation across External Beam Radiotherapy (EBRT) and Brachytherapy (BT) treatment fractions in cervical cancer is extremely challenging due to structural dissimilarities and large inter-fractional anatomic deformations between the EBRT and BT images. The brachytherapy applicator and the bladder balloon, present only in the BT images, introduce missing structural correspondences for the underlying registration problem. Complex anatomical deformations caused by the applicator and the balloon, different rectum and bladder filling and tumor shrinkage compound the registration difficulties. Conventional free-form registration methods struggle to handle such topological differences. In this paper, we propose a registration pipeline that first transforms the original images to their distance maps based on segmentations of critical organs and then performs non-linear registration of the distance maps. The resulting dense deformation field is then used to transform the original anatomical image. The registration accuracy is evaluated on 27 image pairs from stage 2B-4A cervical cancer patients. The algorithm reaches a Hausdorff distance of close to 0:5 mm for the uterus, 2:2 mm for the bladder and 1:7 mm for the rectum when applied to (EBRT,BT) pairs, taken at time points more than three months apart. This generalized model-free framework can be used to register any combination of EBRT and BT images as opposed to methods in the literature that are tuned for either only (BT,BT) pair, or only (EBRT,EBRT) pair or only (BT,EBRT) pair. A unified framework for 3D dose accumulation across multiple EBRT and BT fractions is proposed to facilitate adaptive personalized radiation therapy.

  5. A correlation study on position and volume variation of primary lung cancer during respiration by four-dimensional CT

    International Nuclear Information System (INIS)

    Objective: To investigate the correlation of position movement of primary tumor with interested organs and skin markers, and to investigate the correlation of volume variation of primary tumors and lungs during different respiration phases for patients with lung cancer at free breath condition scanned by four-dimensional CT (4DCT) simulation. Methods: 16 patients with lung cancer were scanned at free breath condition by simulation 4DCT which connected to a respiration-monitoring system. A coordinate system was created based on image of T5 phase,gross tumor volume (GTV) and normal tissue structures of 10 phases were contoured. The three dimensional position variation of them were measured and their correlation were analyzed, and the same for the volume variation of GTV and lungs of 10 respiratory phases. Results: Movement range of lung cancer in different lobe differed extinct: 0.8 - 5.0 mm in upper lobe, 5.7 -5.9 mm in middle lobe and 10.2 - 13.7 mm in lower lobe, respectively. Movement range of lung cancer in three dimensional direction was different: z-axis 4.3 mm ± 4.3 mm > y-axis 2.2 mm ± 1.0 mm > x-axis 1.7 mm ± 1.5 mm (χ2 =16.22, P =0.000), respectively. There was no statistical significant correlation for movement vector of GTV and interested structures (r =-0.50 - -0.01, P =0.058 - -0.961), nor for volume variation of tumor and lung (r =0.23, P =0.520). Conclusions: Based on 4DCT, statistically significant differences of GTV centroid movement are observed at different pulmonary lobes and in three dimensional directions. So individual 4DCT measurement is necessary for definition of internal target volume margin for lung cancer. (authors)

  6. Evaluation of the respiratory prostate motion with four-dimensional computed tomography scan acquisitions using three implanted markers

    International Nuclear Information System (INIS)

    Background and purpose: During the irradiation of the prostate cancer, it is crucial to take into account the possible displacements in defining the planning target volume. The objective of this study was to specifically analyze the respiratory-induced prostate motion using a four-dimensional CT scan (4DCT). Materials and methods: Ten patients have been treated for prostate cancer in the supine position and with three implanted gold markers; they underwent a 4DCT using a GE LightSpeed16® CT scan (slice thickness 2.5 mm). This acquisition was divided into 10 phases over the respiratory cycle using the Advantage4D software. For each phase, digitally-reconstructed radiographs (DRRs) were created at 0° and 90° with the view of the markers. The coordinates of each marker center were generated from the scan isocenter. The motion amplitude was: visually analyzed on the dynamic 4DCT sequences and then more precisely calculated by comparing the marker coordinates on the 10 scans. Results: There was not any difficulty in defining the coordinates of the markers on each series. No prostate motion was observed on a simple visual analysis of the dynamic 4DCT sequences. After a more specific analysis, using the coordinates of the fiducials on the 10 phases, the prostate motion remained below 1 mm in all directions, except for the cranio-caudal, where it was undetectable (thereby below the slice thickness of 2.5 mm). Conclusions: To our knowledge, this is the first study that evaluates the respiratory-induced prostate motion, using a 4DCT scan. Even if important prostate displacement can occur during the prostate treatment, because of the bladder or rectum filling, in the present study no respiratory-induced prostate motion was observed.

  7. Scapholunate kinematics of asymptomatic wrists in comparison with symptomatic contralateral wrists using four-dimensional CT examinations: initial clinical experience

    International Nuclear Information System (INIS)

    Using four-dimensional CT scan (4DCT), we aimed at showing the kinematics of scapholunate (SL) interval in asymptomatic wrists in comparison with symptomatic contralateral wrists with inconclusive radiographic findings. This is an IRB approved, HIPPA compliant, retrospective study. Patients suspected of SL interosseous ligament (SLIL) injuries were referred for further evaluation of chronic wrist pain (>3 months). Twelve wrists (11 subjects) with chronic symptoms and inconclusive plain radiographs and 10 asymptomatic wrists (in 10 different subjects) were scanned using 4DCT. The minimum SL interval was measured during three wrist motions: relaxed-to-clenched fist, flexion-to-extension, and radial-to-ulnar-deviation. Changes were recorded using double-oblique multiplanar reformation technique. We extracted the normal limits of the SL interval as measured by dynamic CT scanning during active motion in asymptomatic wrists. In asymptomatic wrists, the average SL interval was observed to be smaller than 1 mm during all motions. In symptomatic wrists, during exams performed with clenched fist (SL interval (mean ± SD) = 2.53 ± 1.19 mm), extension (2.54 ± 1.48 mm) or ulnar deviation (2.06 ± 1.12 mm), the average SL interval was more than 2 mm. In contrast to symptomatic wrists, no significant change in SL interval measurements was detected during wrist motions in asymptomatic wrists. There was a mild to moderate correlation between SL interval change and presence/absence of symptoms (point-biserial correlation coefficients: 0.29-0.55). In patients with wrist pain suspicious for SLIL injury and inconclusive radiographs, SL interval increase can be detected with 4DCT in the symptomatic wrist compared to the asymptomatic wrist. (orig.)

  8. Scapholunate kinematics of asymptomatic wrists in comparison with symptomatic contralateral wrists using four-dimensional CT examinations: initial clinical experience

    Energy Technology Data Exchange (ETDEWEB)

    Demehri, Shadpour; Hafezi-Nejad, Nima; Morelli, John N.; Thakur, Uma; Eng, John [Johns Hopkins University, Musculoskeletal Radiology, Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Lifchez, Scott D.; Shores, Jaimie T. [Johns Hopkins University, Department of Plastic and Reconstructive Surgery, Baltimore, MD (United States); Means, Kenneth R. [MedStar Union Memorial Hospital, The Curtis National Hand Center, Baltimore, MD (United States)

    2016-04-15

    Using four-dimensional CT scan (4DCT), we aimed at showing the kinematics of scapholunate (SL) interval in asymptomatic wrists in comparison with symptomatic contralateral wrists with inconclusive radiographic findings. This is an IRB approved, HIPPA compliant, retrospective study. Patients suspected of SL interosseous ligament (SLIL) injuries were referred for further evaluation of chronic wrist pain (>3 months). Twelve wrists (11 subjects) with chronic symptoms and inconclusive plain radiographs and 10 asymptomatic wrists (in 10 different subjects) were scanned using 4DCT. The minimum SL interval was measured during three wrist motions: relaxed-to-clenched fist, flexion-to-extension, and radial-to-ulnar-deviation. Changes were recorded using double-oblique multiplanar reformation technique. We extracted the normal limits of the SL interval as measured by dynamic CT scanning during active motion in asymptomatic wrists. In asymptomatic wrists, the average SL interval was observed to be smaller than 1 mm during all motions. In symptomatic wrists, during exams performed with clenched fist (SL interval (mean ± SD) = 2.53 ± 1.19 mm), extension (2.54 ± 1.48 mm) or ulnar deviation (2.06 ± 1.12 mm), the average SL interval was more than 2 mm. In contrast to symptomatic wrists, no significant change in SL interval measurements was detected during wrist motions in asymptomatic wrists. There was a mild to moderate correlation between SL interval change and presence/absence of symptoms (point-biserial correlation coefficients: 0.29-0.55). In patients with wrist pain suspicious for SLIL injury and inconclusive radiographs, SL interval increase can be detected with 4DCT in the symptomatic wrist compared to the asymptomatic wrist. (orig.)

  9. Determination of patient-specific internal gross tumor volumes for lung cancer using four-dimensional computed tomography

    International Nuclear Information System (INIS)

    To determine the optimal approach to delineating patient-specific internal gross target volumes (IGTV) from four-dimensional (4-D) computed tomography (CT) image data sets used in the planning of radiation treatment for lung cancers. We analyzed 4D-CT image data sets of 27 consecutive patients with non-small-cell lung cancer (stage I: 17, stage III: 10). The IGTV, defined to be the envelope of respiratory motion of the gross tumor volume in each 4D-CT data set was delineated manually using four techniques: (1) combining the gross tumor volume (GTV) contours from ten respiratory phases (IGTVAllPhases); (2) combining the GTV contours from two extreme respiratory phases (0% and 50%) (IGTV2Phases); (3) defining the GTV contour using the maximum intensity projection (MIP) (IGTVMIP); and (4) defining the GTV contour using the MIP with modification based on visual verification of contours in individual respiratory phase (IGTVMIP-Modified). Using the IGTVAllPhases as the optimum IGTV, we compared volumes, matching indices, and extent of target missing using the IGTVs based on the other three approaches. The IGTVMIP and IGTV2Phases were significantly smaller than the IGTVAllPhases (p < 0.006 for stage I and p < 0.002 for stage III). However, the values of the IGTVMIP-Modified were close to those determined from IGTVAllPhases (p = 0.08). IGTVMIP-Modified also matched the best with IGTVAllPhases. IGTVMIP and IGTV2Phases underestimate IGTVs. IGTVMIP-Modified is recommended to improve IGTV delineation in lung cancer

  10. Estimation of emission adjustments from the application of four-dimensional data assimilation to photochemical air quality modeling

    International Nuclear Information System (INIS)

    Four-dimensional data assimilation applied to photochemical air quality modeling is used to suggest adjustments to the emissions inventory of the Atlanta, Georgia metropolitan area. In this approach, a three-dimensional air quality model, coupled with direct sensitivity analysis, develops spatially and temporally varying concentration and sensitivity fields that account for chemical and physical processing, and receptor analysis is used to adjust source strengths. Proposed changes to domain-wide NOx, volatile organic compounds (VOCs) and CO emissions from anthropogenic sources and for VOC emissions from biogenic sources were estimated, as well as modifications to sources based on their spatial location (urban vs. rural areas). In general, domain-wide anthropogenic VOC emissions were increased approximately two times their base case level to best match observations, domain-wide anthropogenic NOx and biogenic VOC emissions (BEIS2 estimates) remained close to their base case value and domain-wide CO emissions were decreased. Adjustments for anthropogenic NOx emissions increased their level of uncertainty when adjustments were computed for mobile and area sources (or urban and rural sources) separately, due in part to the poor spatial resolution of the observation field of nitrogen-containing species. Estimated changes to CO emissions also suffer from poor spatial resolution of the measurements. Results suggest that rural anthropogenic VOC emissions appear to be severely underpredicted. The FDDA approach was also used to investigate the speciation profiles of VOC emissions, and results warrant revision of these profiles. In general, the results obtained here are consistent with what are viewed as the current deficiencies in emissions inventories as derived by other top-down techniques, such as tunnel studies and analysis of ambient measurements. (Author)

  11. Correlation of primary middle and distal esophageal cancers motion with surrounding tissues using four-dimensional computed tomography

    Science.gov (United States)

    Wang, Wei; Li, Jianbin; Zhang, Yingjie; Shao, Qian; Xu, Min; Guo, Bing; Shang, Dongping

    2016-01-01

    Purpose To investigate the correlation of gross tumor volume (GTV) motion with the structure of interest (SOI) motion and volume variation for middle and distal esophageal cancers using four-dimensional computed tomography (4DCT). Patients and methods Thirty-three patients with middle or distal esophageal carcinoma underwent 4DCT simulation scan during free breathing. All image sets were registered with 0% phase, and the GTV, apex of diaphragm, lung, and heart were delineated on each phase of the 4DCT data. The position of GTV and SOI was identified in all 4DCT phases, and the volume of lung and heart was also achieved. The phase relationship between the GTV and SOI was estimated through Pearson’s correlation test. Results The mean peak-to-peak displacement of all primary tumors in the lateral (LR), anteroposterior (AP), and superoinferior (SI) directions was 0.13 cm, 0.20 cm, and 0.30 cm, respectively. The SI peak-to-peak motion of the GTV was defined as the greatest magnitude of motion. The displacement of GTV correlated well with heart in three dimensions and significantly associated with bilateral lung in LR and SI directions. A significant correlation was found between the GTV and apex of the diaphragm in SI direction (rleft=0.918 and rright=0.928). A significant inverse correlation was found between GTV motion and varying lung volume, but the correlation was not significant with heart (rLR=−0.530, rAP=−0.531, and rSI=−0.588) during respiratory cycle. Conclusion For middle and distal esophageal cancers, GTV should expand asymmetric internal margins. The primary tumor motion has quite good correlation with diaphragm, heart, and lung.

  12. Differentiation of Brain Tumor Recurrence from Post-Radiotherapy Necrosis with 11C-Methionine PET: Visual Assessment versus Quantitative Assessment.

    Directory of Open Access Journals (Sweden)

    Ryogo Minamimoto

    Full Text Available The aim of this multi-center study was to assess the diagnostic capability of visual assessment in L-methyl-11C-methionine positron emission tomography (MET-PET for differentiating a recurrent brain tumor from radiation-induced necrosis after radiotherapy, and to compare it to the accuracy of quantitative analysis.A total of 73 brain lesions (glioma: 31, brain metastasis: 42 in 70 patients who underwent MET-PET were included in this study. Visual analysis was performed by comparison of MET uptake in the brain lesion with MET uptake in one of four regions (around the lesion, contralateral frontal lobe, contralateral area, and contralateral cerebellar cortex. The concordance rate and logistic regression analysis were used to evaluate the diagnostic ability of visual assessment. Receiver-operating characteristic curve analysis was used to compare visual assessment with quantitative assessment based on the lesion-to-normal (L/N ratio of MET uptake.Interobserver and intraobserver κ-values were highest at 0.657 and 0.714, respectively, when assessing MET uptake in the lesion compared to that in the contralateral cerebellar cortex. Logistic regression analysis showed that assessing MET uptake in the contralateral cerebellar cortex with brain metastasis was significantly related to the final result. The highest area under the receiver-operating characteristic curve (AUC with visual assessment for brain metastasis was 0.85, showing no statistically significant difference with L/Nmax of the contralateral brain (AUC = 0.89 or with L/Nmean of the contralateral cerebellar cortex (AUC = 0.89, which were the areas that were the highest in the quantitative assessment. For evaluation of gliomas, no specific candidate was confirmed among the four areas used in visual assessment, and no significant difference was seen between visual assessment and quantitative assessment.The visual assessment showed no significant difference from quantitative assessment of MET

  13. Patient safety in external beam radiotherapy – Guidelines on risk assessment and analysis of adverse error-events and near misses: Introducing the ACCIRAD project

    International Nuclear Information System (INIS)

    In 2011 the European Commission launched a tender to develop guidelines for risk analysis of accidental and unintended exposures in external beam radiotherapy. This tender was awarded to a consortium of 6 institutions, including the ESTRO, in late 2011. The project, denominated “ACCIRAD”, recently finished the data collection phase. Data were collected by surveys administered in 38 European countries. Results indicate non-uniform implementation of event registration and classification, as well as incomplete or zero implementation of risk assessment and events analysis. Based on the survey results and analysis thereof, project leaders are currently drafting proposed guidelines entitled “Guidelines for patient safety in external beam radiotherapy – Guidelines on risk assessment and analysis of adverse-error events and near misses”. The present article describes the aims and current status of the project, including results of the surveys

  14. On the one-loop effective potential in the higher-derivative four-dimensional chiral superfield theory with a nonconventional kinetic term

    International Nuclear Information System (INIS)

    We explicitly calculate the one-loop effective potential for a higher-derivative four-dimensional chiral superfield theory with a nonconventional kinetic term. We consider the cases of minimal and nonminimal general Lagrangians. In particular, we find that in the minimal case the divergent part of the one-loop effective potential vanishes by reason of the chirality.

  15. USE OF FOUR-DIMENSIONAL DATA ASSIMILATION IN A LIMITED-AREA MESOSCALE MODEL - PART II: EFFECTS OF DATA ASSIMILATION WITHIN THE PLANETARY BOUNDARY LAYER

    Science.gov (United States)

    A four-dimensional data assimilation (FDDA) scheme based on Newtonian relaxation or nudging has been developed and evaluated in the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) Limited-Area Mesoscale Model. t was shown in Part I of this study ...

  16. To what extent does the anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) detect specific types of anxiety disorder in primary care? A psychometric study

    NARCIS (Netherlands)

    Terluin, B.; Oosterbaan, D.B.; Brouwers, E.P.; Straten, A. van; Ven, P.M. van de; Langerak, W.; Marwijk, H.W.J. van

    2014-01-01

    BACKGROUND: Anxiety scales may help primary care physicians to detect specific anxiety disorders among the many emotionally distressed patients presenting in primary care. The anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) consists of an admixture of symptoms of specific anxiety

  17. The Hawking temperature in the context of dark energy for four-dimensional asymptotically AdS black holes with scalar hair

    OpenAIRE

    Naji, J

    2014-01-01

    In this paper, we considered new solutions for four-dimensional asymptotically AdS black holes with scalar hair and discuss about Hawking temperature in the context of dark energy by using the tunneling method. We obtain modification of the Hawking temperature due to presence of the dark energy.

  18. Assessment of myocardial metabolic disorder associated with mediastinal radiotherapy for esophageal cancer -a pilot study-

    International Nuclear Information System (INIS)

    To evaluate the dose-effect relations for myocardial metabolic disorders after mediastinal radiotherapy (RT) by performing iodine-123 β-methyl-iodophenyl pentadecanoic acid (I-123 BMIPP) scintigraphy. Between 2011 and 2012, we performed I-123 BMIPP scintigraphy for patients with esophageal cancer before and six months after curative mediastinal RT. Single photon emission computed tomography (SPECT) images of pre-RT and post-RT were registered into RT dose distributions. The myocardium was contoured, and the regional RT dose was calculated. Normalization is required to compare pre- and post-RT SPECT images because the uptake pattern is changed due to the breathing level. Normalization was applied on the mean of SPECT counts in regions of the myocardium receiving less than 5 Gy. Relative values in each dose region (interval of 5 Gy) were calculated on the basis of this normalization for each patient. The reduction in the percent of relative values was calculated. Five patients were enrolled in this study. None of the patients had a past history of cardiac disease. The left ventricle was partially involved in RT fields in all patients. The patients received RT with median total doses of 60-66 Gy for the primary tumor and metastatic lymph nodes. Concomitant chemotherapy consisting of cisplatin or nedaplatin and 5-fluorouracil with RT was performed in 4 patients. All patients had reduced uptake corresponding to RT fields. Dose-effect relations for reduced uptake tended to be observed at 6 months after RT with mean decreases of 8.96% in regions at 10-15 Gy, 12.6% in regions at 20-25 Gy, 15.6% in regions at 30-35 Gy, 19.0% in regions at 40-45 Gy and 16.0% in regions at 50-55 Gy. Dose-effect relations for myocardial metabolic disorders tended to be observed. We may need to make an effort to reduce high-dose mediastinal RT to the myocardium in RT planning

  19. Quantitative dosimetric assessment for effect of gold nanoparticles as contrast media on radiotherapy planning

    Science.gov (United States)

    Tu, Shu-Ju; Yang, Pei-Ying; Hong, Ji-Hong; Lo, Ching-Jung

    2013-07-01

    In CT planning for radiation therapy, patients may be asked to have a medical procedure of contrast agent (CA) administration as required by their physicians. CA media improve quality of CT images and assist radiation oncologists in delineation of the target or organs with accuracy. However, dosimetric discrepancy may occur between scenarios in which CA media are present in CT planning and absent in treatment delivery. In recent preclinical experiments of small animals, gold nanoparticles (AuNPs) have been identified as an excellent contrast material of x-ray imaging. In this work, we quantitatively evaluate the effect of AuNPs to be used as a potential material of contrast enhancement in radiotherapy planning with an analytical phantom and clinical case. Conray 60, an iodine-based product for contrast enhancement in clinical uses, is included as a comparison. Other additional variables such as different concentrations of CA media, radiation delivery techniques and dose calculation algorithms are included. We consider 1-field AP, 4-field box, 7-field intensity modulated radiation therapy (IMRT) and a recent technique of volumetric modulated arc therapy (VMAT). CA media of AuNPs (Conray 60) with concentrations of 10%, 20%, 30%, 40% and 50% containing 28.2, 56.4, 84.6, 112.8 and 141.0 mg of gold (iodine) per mL were prepared prior to CT scanning. A virtual phantom with a target where nanoparticle media are loaded and clinical case of gastric lymphoma in which the Conray 60 media were given to the patient prior to the CT planning are included for the study. Compared to Conray 60 media with concentration of 10%/50%, Hounsfield units for AuNP media of 10%/50% are 322/1608 higher due to the fact that atomic number of Au (Z=79) is larger than I (Z=53). In consequence, dosimetric discrepancy of AuNPs is magnified between presence and absence of contrast media. It was found in the phantom study that percent dose differences between presence and absence of CA media may be

  20. Assessment of risks of stenosis of the anal canal during a prostatic radiotherapy

    International Nuclear Information System (INIS)

    The authors report a study which aimed at assessing the late tolerance of a prostatic irradiation at the rectum and anal canal level. They assessed the length of the rectum and of the anal canal after prostate irradiation or surgery in patients who suffered from a prostate adenocarcinoma. Data of 154 patients have been analyzed regarding the number of cases of stenosis of rectum or anal canal. They highlight the importance of the irradiated length and dose level. Short communication

  1. Results of postoperative {sup 90}Sr radiotherapy of keloids in view of patients' subjective assessment

    Energy Technology Data Exchange (ETDEWEB)

    Fraunholz, I.B.; Gerstenhauer, A.; Boettcher, H.D. [Frankfurt am Main Univ. (Germany). Dept. of Radiation Oncology

    2005-11-01

    Background and Purpose: As treatment of keloids is mainly a cosmetic indication, the authors investigated, beyond the recurrence rate, the patients' satisfaction with the result and its correlation with objective medical findings. Patients and Methods: 83 keloids of 66 patients had been irradiated after excision by a uniform protocol with 4 x 5 Gy (strontium-90 [{sup 90}Sr] surface applicator). A questionnaire was developed and sent out in which, above all, the satisfaction with the therapeutic and cosmetic outcome was obtained. These results were correlated with objective parameters and medical findings which were ascertained during an extra follow-up examination. Results: Among 18 of the 41 patients (44%), who had answered the questionnaire, 19 of the 53 keloids treated (36%) had relapsed. 61% of the patients were extremely or mainly satisfied with the therapeutic outcome, 51% extremely or mainly satisfied with the cosmetic outcome. The relief from former keloid-caused symptoms (therapeutic outcome: p=0.0005; cosmetic outcome: p=0.0011), the ear as keloid localization (p=0.0008 and p=0.0197), and male gender (therapeutic outcome: p=0.0423) were significantly associated with higher satisfaction. The recurrence rate as well as the extent of radiation side effects had no significant influence on patients' assessment. Conclusion: Cosmetic aspects like the dermal side effects and the patients' satisfaction should be taken into account when evaluating the results of radiotherapy in keloids. (orig.)

  2. Magnetic resonance imaging for assessment of parametrial tumour spread and regression patterns in adaptive cervix cancer radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Maximilian P.; Fidarova, Elena [Dept. of Radiotherapy, Comprehensive Cancer Center, Medical Univ. of Vienna, Vienna (Austria)], e-mail: maximilian.schmid@akhwien.at; Poetter, Richard [Dept. of Radiotherapy, Comprehensive Cancer Center, Medical Univ. of Vienna, Vienna (Austria); Christian Doppler Lab. for Medical Radiation Research for Radiation Oncology, Medical Univ. of Vienna (Austria)] [and others

    2013-10-15

    Purpose: To investigate the impact of magnetic resonance imaging (MRI)-morphologic differences in parametrial infiltration on tumour response during primary radio chemotherapy in cervical cancer. Material and methods: Eighty-five consecutive cervical cancer patients with FIGO stages IIB (n = 59) and IIIB (n = 26), treated by external beam radiotherapy ({+-}chemotherapy) and image-guided adaptive brachytherapy, underwent T2-weighted MRI at the time of diagnosis and at the time of brachytherapy. MRI patterns of parametrial tumour infiltration at the time of diagnosis were assessed with regard to predominant morphology and maximum extent of parametrial tumour infiltration and were stratified into five tumour groups (TG): 1) expansive with spiculae; 2) expansive with spiculae and infiltrating parts; 3) infiltrative into the inner third of the parametrial space (PM); 4) infiltrative into the middle third of the PM; and 5) infiltrative into the outer third of the PM. MRI at the time of brachytherapy was used for identifying presence (residual vs. no residual disease) and signal intensity (high vs. intermediate) of residual disease within the PM. Left and right PM of each patient were evaluated separately at both time points. The impact of the TG on tumour remission status within the PM was analysed using {chi}2-test and logistic regression analysis. Results: In total, 170 PM were analysed. The TG 1, 2, 3, 4, 5 were present in 12%, 11%, 35%, 25% and 12% of the cases, respectively. Five percent of the PM were tumour-free. Residual tumour in the PM was identified in 19%, 68%, 88%, 90% and 85% of the PM for the TG 1, 2, 3, 4, and 5, respectively. The TG 3 - 5 had significantly higher rates of residual tumour in the PM in comparison to TG 1 + 2 (88% vs. 43%, p < 0.01). Conclusion: MRI-morphologic features of PM infiltration appear to allow for prediction of tumour response during external beam radiotherapy and chemotherapy. A predominantly infiltrative tumour spread at the

  3. SU-C-207-01: Four-Dimensional Inverse Geometry Computed Tomography: Concept and Its Validation

    International Nuclear Information System (INIS)

    Purpose: In past few years, the inverse geometry computed tomography (IGCT) system has been developed to overcome shortcomings of a conventional computed tomography (CT) system such as scatter problem induced from large detector size and cone-beam artifact. In this study, we intend to present a concept of a four-dimensional (4D) IGCT system that has positive aspects above all with temporal resolution for dynamic studies and reduction of motion artifact. Methods: Contrary to conventional CT system, projection data at a certain angle in IGCT was a group of fractionated narrow cone-beam projection data, projection group (PG), acquired from multi-source array which have extremely short time gap of sequential operation between each of sources. At this, for 4D IGCT imaging, time-related data acquisition parameters were determined by combining multi-source scanning time for collecting one PG with conventional 4D CBCT data acquisition sequence. Over a gantry rotation, acquired PGs from multi-source array were tagged time and angle for 4D image reconstruction. Acquired PGs were sorted into 10 phase and image reconstructions were independently performed at each phase. Image reconstruction algorithm based upon filtered-backprojection was used in this study. Results: The 4D IGCT had uniform image without cone-beam artifact on the contrary to 4D CBCT image. In addition, the 4D IGCT images of each phase had no significant artifact induced from motion compared with 3D CT. Conclusion: The 4D IGCT image seems to give relatively accurate dynamic information of patient anatomy based on the results were more endurable than 3D CT about motion artifact. From this, it will be useful for dynamic study and respiratory-correlated radiation therapy. This work was supported by the Industrial R&D program of MOTIE/KEIT [10048997, Development of the core technology for integrated therapy devices based on real-time MRI guided tumor tracking] and the Mid-career Researcher Program (2014R1A2A1A

  4. Improving thoracic four-dimensional cone-beam CT reconstruction with anatomical-adaptive image regularization (AAIR)

    International Nuclear Information System (INIS)

    Total-variation (TV) minimization reconstructions can significantly reduce noise and streaks in thoracic four-dimensional cone-beam computed tomography (4D CBCT) images compared to the Feldkamp–Davis–Kress (FDK) algorithm currently used in practice. TV minimization reconstructions are, however, prone to over-smoothing anatomical details and are also computationally inefficient. The aim of this study is to demonstrate a proof of concept that these disadvantages can be overcome by incorporating the general knowledge of the thoracic anatomy via anatomy segmentation into the reconstruction. The proposed method, referred as the anatomical-adaptive image regularization (AAIR) method, utilizes the adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS) framework, but introduces an additional anatomy segmentation step in every iteration. The anatomy segmentation information is implemented in the reconstruction using a heuristic approach to adaptively suppress over-smoothing at anatomical structures of interest. The performance of AAIR depends on parameters describing the weighting of the anatomy segmentation prior and segmentation threshold values. A sensitivity study revealed that the reconstruction outcome is not sensitive to these parameters as long as they are chosen within a suitable range. AAIR was validated using a digital phantom and a patient scan and was compared to FDK, ASD-POCS and the prior image constrained compressed sensing (PICCS) method. For the phantom case, AAIR reconstruction was quantitatively shown to be the most accurate as indicated by the mean absolute difference and the structural similarity index. For the patient case, AAIR resulted in the highest signal-to-noise ratio (i.e. the lowest level of noise and streaking) and the highest contrast-to-noise ratios for the tumor and the bony anatomy (i.e. the best visibility of anatomical details). Overall, AAIR was much less prone to over-smoothing anatomical details compared to ASD-POCS and

  5. Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET

    Directory of Open Access Journals (Sweden)

    G. Pappalardo

    2012-11-01

    Full Text Available The eruption of the Icelandic volcano Eyjafjallajökull in April/May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET. Based on multi-wavelength Raman lidar systems EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude.

    In this work we show the four-dimensional (4-D distribution of the Eyjafjallajökull volcanic cloud over Europe as observed by EARLINET during the entire volcanic event (15 April–26 May 2010. All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio are stored in the EARLINET database available at http://www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at http://www.earlinet.org.

    During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the lower stratosphere down to the local Planetary Boundary Layer (PBL. After 19 April 2010, volcanic particles were detected over South and South Eastern Europe. During the first half of May (5–15 May, material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. Last observations of the event were recorded until 25 May in Central Europe and in the Eastern

  6. SU-C-207-01: Four-Dimensional Inverse Geometry Computed Tomography: Concept and Its Validation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K; Kim, D; Kim, T; Kang, S; Cho, M; Shin, D; Suh, T [The Catholic University of Korea, Seoul (Korea, Republic of)

    2015-06-15

    Purpose: In past few years, the inverse geometry computed tomography (IGCT) system has been developed to overcome shortcomings of a conventional computed tomography (CT) system such as scatter problem induced from large detector size and cone-beam artifact. In this study, we intend to present a concept of a four-dimensional (4D) IGCT system that has positive aspects above all with temporal resolution for dynamic studies and reduction of motion artifact. Methods: Contrary to conventional CT system, projection data at a certain angle in IGCT was a group of fractionated narrow cone-beam projection data, projection group (PG), acquired from multi-source array which have extremely short time gap of sequential operation between each of sources. At this, for 4D IGCT imaging, time-related data acquisition parameters were determined by combining multi-source scanning time for collecting one PG with conventional 4D CBCT data acquisition sequence. Over a gantry rotation, acquired PGs from multi-source array were tagged time and angle for 4D image reconstruction. Acquired PGs were sorted into 10 phase and image reconstructions were independently performed at each phase. Image reconstruction algorithm based upon filtered-backprojection was used in this study. Results: The 4D IGCT had uniform image without cone-beam artifact on the contrary to 4D CBCT image. In addition, the 4D IGCT images of each phase had no significant artifact induced from motion compared with 3D CT. Conclusion: The 4D IGCT image seems to give relatively accurate dynamic information of patient anatomy based on the results were more endurable than 3D CT about motion artifact. From this, it will be useful for dynamic study and respiratory-correlated radiation therapy. This work was supported by the Industrial R&D program of MOTIE/KEIT [10048997, Development of the core technology for integrated therapy devices based on real-time MRI guided tumor tracking] and the Mid-career Researcher Program (2014R1A2A1A

  7. Improving thoracic four-dimensional cone-beam CT reconstruction with anatomical-adaptive image regularization (AAIR)

    Science.gov (United States)

    Shieh, Chun-Chien; Kipritidis, John; O'Brien, Ricky T.; Cooper, Benjamin J.; Kuncic, Zdenka; Keall, Paul J.

    2015-01-01

    Total-variation (TV) minimization reconstructions can significantly reduce noise and streaks in thoracic four-dimensional cone-beam computed tomography (4D CBCT) images compared to the Feldkamp-Davis-Kress (FDK) algorithm currently used in practice. TV minimization reconstructions are, however, prone to over-smoothing anatomical details and are also computationally inefficient. The aim of this study is to demonstrate a proof of concept that these disadvantages can be overcome by incorporating the general knowledge of the thoracic anatomy via anatomy segmentation into the reconstruction. The proposed method, referred as the anatomical-adaptive image regularization (AAIR) method, utilizes the adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS) framework, but introduces an additional anatomy segmentation step in every iteration. The anatomy segmentation information is implemented in the reconstruction using a heuristic approach to adaptively suppress over-smoothing at anatomical structures of interest. The performance of AAIR depends on parameters describing the weighting of the anatomy segmentation prior and segmentation threshold values. A sensitivity study revealed that the reconstruction outcome is not sensitive to these parameters as long as they are chosen within a suitable range. AAIR was validated using a digital phantom and a patient scan and was compared to FDK, ASD-POCS and the prior image constrained compressed sensing (PICCS) method. For the phantom case, AAIR reconstruction was quantitatively shown to be the most accurate as indicated by the mean absolute difference and the structural similarity index. For the patient case, AAIR resulted in the highest signal-to-noise ratio (i.e. the lowest level of noise and streaking) and the highest contrast-to-noise ratios for the tumor and the bony anatomy (i.e. the best visibility of anatomical details). Overall, AAIR was much less prone to over-smoothing anatomical details compared to ASD-POCS and did

  8. Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET

    Directory of Open Access Journals (Sweden)

    G. Pappalardo

    2013-04-01

    Full Text Available The eruption of the Icelandic volcano Eyjafjallajökull in April–May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET. Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D distribution of the Eyjafjallajökull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April–26 May 2010. All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio are stored in the EARLINET database available at http://www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at http://www.earlinet.org. During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL. After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5–15 May, material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern Mediterranean area. The 4-D distribution of volcanic aerosol layering and optical properties on

  9. Assessment of response of brain metastases to radiotherapy by PET imaging of apoptosis with 18F-ML-10

    International Nuclear Information System (INIS)

    Early assessment of tumor response to therapy is vital for treatment optimization for the individual cancer patient. Induction of apoptosis is an early and nearly universal effect of anticancer therapies. The purpose of this study was to assess the performance of 18F-ML-10, a novel PET radiotracer for apoptosis, as a tool for the early detection of response of brain metastases to whole-brain radiation therapy (WBRT). Ten patients with brain metastases treated with WBRT at 30 Gy in ten daily fractions were enrolled in this trial. Each patient underwent two 18F-ML-10 PET scans, one prior to the radiation therapy (baseline scan), and the second after nine or ten fractions of radiotherapy (follow-up scan). MRI was performed at 6-8 weeks following completion of the radiation therapy. Early treatment-induced changes in tumor 18F-ML-10 uptake on the PET scan were measured by voxel-based analysis, and were then evaluated by correlation analysis as predictors of the extent of later changes in tumor anatomical dimensions as seen on MRI scans 6-8 weeks after completion of therapy. In all ten patients, all brain lesions were detected by both MRI and the 18F-ML-10 PET scan. A highly significant correlation was found between early changes on the 18F-ML-10 scan and later changes in tumor anatomical dimensions (r = 0.9). These results support the potential of 18F-ML-10 PET as a novel tool for the early detection of response of brain metastases to WBRT. (orig.)

  10. Neurocognitive function impairment after whole brain radiotherapy for brain metastases: actual assessment

    International Nuclear Information System (INIS)

    Whole brain radiation therapy (WBRT) is an effective treatment in brain metastases and, when combined with local treatments such as surgery and stereotactic radiosurgery, gives the best brain control. Nonetheless, WBRT is often omitted after local treatment due to its potential late neurocognitive effects. Publications on radiation-induced neurotoxicity have used different assessment methods, time to assessment, and definition of impairment, thus making it difficult to accurately assess the rate and magnitude of the neurocognitive decline that can be expected. In this context, and to help therapeutic decision making, we have conducted this literature review, with the aim of providing an average incidence, magnitude and time to occurrence of radio-induced neurocognitive decline. We reviewed all English language published articles on neurocognitive effects of WBRT for newly diagnosed brain metastases or with a preventive goal in adult patients, with any methodology (MMSE, battery of neurcognitive tests) with which baseline status was provided. We concluded that neurocognitive decline is predominant at 4 months, strongly dependant on brain metastases control, partially solved at later time, graded 1 on a SOMA-LENT scale (only 8% of grade 2 and more), insufficiently assessed in long-term survivors, thus justifying all efforts to reduce it through irradiation modulation

  11. Analysis of agreement between Visual Analogue Scales (VAS and numerical questions to assess perception of teratogenic risks in treatment with drugs and radiotherapy in women

    Directory of Open Access Journals (Sweden)

    Emilia da Silva Pons

    2014-12-01

    Full Text Available Objectives: to evaluate the agreement between Visual Analogue Scales (VAS and numerical questions as a way of assessing the perception of teratogenic risk of treatment with drugs and radiotherapy. Methods: the sample comprised 144 pregnant and 143 non-pregnant women consecutively recruited at public health centers in Porto Alegre, in the State of Rio Grande do Sul, from February to August 2011. The perception of risk for congenital malformations in the general population and the perceptions of teratogenic risk for exposure to acetaminophen, meto-clopramide, misoprostol and radiotherapy were measured using VAS and numerical questions. The agreement between the results of the two techniques was tested using a Bland-Altman plot. Results: the medians for the perceptions measured using VAS were higher than those obtained using numerical questions for all variables. The perception of risk for acetaminophen showed the lower bias of the two techniques (bias=13.17; p<0.001 and exposure to radiotherapy, the higher (bias=25.02; p<0.001. Conclusion: there was no agreement between the measurements obtained using the two techniques for any of the risk perceptions under study. Risk perceptions were higher using VAS, for all kinds of exposure. Studies should be conducted to assess whether there is overestimation in other situations and social contexts owing to the use of VAS.

  12. Radiotherapy of abdomen with precise renal assessment with SPECT/CT imaging (RAPRASI): design and methodology of a prospective trial to improve the understanding of kidney radiation dose response

    International Nuclear Information System (INIS)

    The kidneys are a principal dose-limiting organ in radiotherapy for upper abdominal cancers. The current understanding of kidney radiation dose response is rudimentary. More precise dose-volume response models that allow direct correlation of delivered radiation dose with spatio-temporal changes in kidney function may improve radiotherapy treatment planning for upper-abdominal tumours. Our current understanding of kidney dose response and tolerance is limited and this is hindering efforts to introduce advanced radiotherapy techniques for upper-abdominal cancers, such as intensity-modulated radiotherapy (IMRT). The aim of this study is to utilise radiotherapy and combined anatomical/functional imaging data to allow direct correlation of radiation dose with spatio-temporal changes in kidney function. The data can then be used to develop a more precise dose-volume response model which has the potential to optimise and individualise upper abdominal radiotherapy plans. The Radiotherapy of Abdomen with Precise Renal Assessment with SPECT/CT Imaging (RAPRASI) is an observational clinical research study with participating sites at Sir Charles Gairdner Hospital (SCGH) in Perth, Australia and the Peter MacCallum Cancer Centre (PMCC) in Melbourne, Australia. Eligible patients are those with upper gastrointestinal cancer, without metastatic disease, undergoing conformal radiotherapy that will involve incidental radiation to one or both kidneys. For each patient, total kidney function is being assessed before commencement of radiotherapy treatment and then at 4, 12, 26, 52 and 78 weeks after the first radiotherapy fraction, using two procedures: a Glomerular Filtration Rate (GFR) measurement using the 51Cr-ethylenediamine tetra-acetic acid (EDTA) clearance; and a regional kidney perfusion measurement assessing renal uptake of 99mTc-dimercaptosuccinic acid (DMSA), imaged with a Single Photon Emission Computed Tomography / Computed Tomography (SPECT/CT) system. The CT component

  13. Phase II study assessing the effectiveness of Biafine cream as a prophylactic agent for radiation-induced acute skin toxicity to the breast in women undergoing radiotherapy with concomitant CMF chemotherapy

    International Nuclear Information System (INIS)

    Purpose: To assess the efficacy of Biafine cream in preventing Grade 2 acute radiation dermatitis, according to the National Cancer Institute of Canada skin radiation toxicity criteria in patients undergoing concomitant adjuvant chemotherapy and radiotherapy to the breast. Methods and Materials: Sixty patients participated in this study. Patients were treated with a lumpectomy followed by concomitant chemotherapy and radiotherapy to the breast. Biafine cream was applied daily, starting on the first day and ending 2 weeks post-radiotherapy. Patients underwent weekly skin assessments throughout radiotherapy and at 2 and 4 weeks after treatment. Outcome measures were assessed using a Skin Assessment Questionnaire that was scored according to the National Cancer Institute of Canada skin radiation toxicity criteria and a self-administered questionnaire that evaluated skin symptoms. Results: The maximum skin toxicity observed during the course of treatment was as follows: less than Grade 2 toxicity, 15% (9 patients); Grade 2, 83% (50 patients); Grade 3, 2% (1 patient); Grade 4, 0% (0 patients). The majority of the radiation dermatitis was observed after 3 weeks of radiotherapy. Conclusion: The majority of patients who underwent concomitant chemo- and radiotherapy for breast cancer developed Grade 2 radiation dermatitis with the use of Biafine cream. However, no treatment delays or interruptions were observed because of skin toxicity

  14. Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J. [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, Sydney NSW 2006 (Australia); Hugo, Geoffrey; Weiss, Elisabeth; Williamson, Jeffrey [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)

    2015-03-15

    Purpose: Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), a novel technique for functional lung imaging. Methods: The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4–6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. Results: The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r{sup -}{sub Inter

  15. 3D quantitative assessment of response to fractionated stereotactic radiotherapy and single-session stereotactic radiosurgery of vestibular schwannoma

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, T. [The Johns Hopkins Hospital School of Medicine, Russell H. Morgan Department of Radiology and Radiological Sciences, Division of Neuroradiology, Baltimore, MD (United States); University Medical Center Hamburg-Eppendorf, Department of Diagnostic and Interventional Neuroradiology, Hamburg (Germany); Chapiro, J. [The Johns Hopkins Hospital School of Medicine, Russell H. Morgan Department of Radiology and Radiological Sciences, Division of Interventional Radiology, Baltimore, MD (United States); Lin, M. [Philips Research North America, Ultrasound Imaging and Interventions (UII), Briarcliff Manor, NY (United States); Geschwind, J.F. [The Johns Hopkins Hospital School of Medicine, Russell H. Morgan Department of Radiology and Radiological Sciences, Division of Interventional Radiology, Baltimore, MD (United States); Yale University School of Medicine, Department of Radiology and Imaging Science, New Haven, CT (United States); Kleinberg, L. [The Johns Hopkins University School of Medicine, Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD (United States); Rigamonti, D.; Jusue-Torres, I.; Marciscano, A.E. [The Johns Hopkins University School of Medicine, Department of Neurological Surgery, Baltimore, MD (United States); Yousem, D.M. [The Johns Hopkins Hospital School of Medicine, Russell H. Morgan Department of Radiology and Radiological Sciences, Division of Neuroradiology, Baltimore, MD (United States)

    2016-03-15

    To determine clinical outcome of patients with vestibular schwannoma (VS) after treatment with fractionated stereotactic radiotherapy (FSRT) and single-session stereotactic radiosurgery (SRS) by using 3D quantitative response assessment on MRI. This retrospective analysis included 162 patients who underwent radiation therapy for sporadic VS. Measurements on T1-weighted contrast-enhanced MRI (in 2-year post-therapy intervals: 0-2, 2-4, 4-6, 6-8, 8-10, 10-12 years) were taken for total tumour volume (TTV) and enhancing tumour volume (ETV) based on a semi-automated technique. Patients were considered non-responders (NRs) if they required subsequent microsurgical resection or developed radiological progression and tumour-related symptoms. Median follow-up was 4.1 years (range: 0.4-12.0). TTV and ETV decreased for both the FSRT and SRS groups. However, only the FSRT group achieved significant tumour shrinkage (p < 0.015 for TTV, p < 0.005 for ETV over time). The 11 NRs showed proportionally greater TTV (median TTV pre-treatment: 0.61 cm{sup 3}, 8-10 years after: 1.77 cm{sup 3}) and ETV despite radiation therapy compared to responders (median TTV pre-treatment: 1.06 cm{sup 3}; 10-12 years after: 0.81 cm{sup 3}; p = 0.001). 3D quantification of VS showed a significant decrease in TTV and ETV on FSRT-treated patients only. NR had significantly greater TTV and ETV over time. (orig.)

  16. Computed tomography to assess pulmonary injury associated with concurrent chemo-radiotherapy for inoperable non-small cell lung cancer

    International Nuclear Information System (INIS)

    To characterize serial computed tomography (CT) findings of pulmonary injury after a uniform regimen of concurrent chemo-radiotherapy in inoperable non-small cell lung cancer, and to compare the radiation-induced lung toxicity with other concurrent chemo-radiation regimens. Twenty-four patients with advanced non-small cell lung cancer received 2 induction cycles of cisplatin and vinblastine, followed by 2 further cycles of cisplatin and vinblastine, concurrent with 60 Gy radiation at 2 Gy per fraction. Radiation-induced lung injury in the acute and chronic phases was assessed by serial CT scans and compared with preradiation baseline scans. Acute radiation pneumonitis was evaluated using the Common Toxicity Criteria, and chronic radiation fibrosis was graded according to the European Organisation for Research and Treatment of Cancer - Radiation Therapy Oncology Group Scale. Seventeen (81%) patients had characteristic CT findings of radiation induced pulmonary damage, which were confined to the radiation ports. Although patchy nonhomogeneous and air-space opacities characterized acute radiation pneumonitis, and homogeneous opacities with loss of volume were typical for chronic fibrosis, ground-glass opacities were found frequently in both phases. Acute radiation pneumonitis grade 1 was seen in 29% and grade 2 in 9.5%. Chronic radiation fibrosis grades 1, 2 and 3 were found in 14%, 33% and 19% of the patients respectively. Median survival time was 13 months. CT enables detailed evaluation of radiation-induced pulmonary injury after concurrent chemo-radiation for inoperable non-small cell lung cancer. Although survival time with the present regimen is comparable to other concurrent chemo-radiation regimens, a high incidence of radiation injury was found, though the severity was not life threatening. (author)

  17. 3D quantitative assessment of response to fractionated stereotactic radiotherapy and single-session stereotactic radiosurgery of vestibular schwannoma

    International Nuclear Information System (INIS)

    To determine clinical outcome of patients with vestibular schwannoma (VS) after treatment with fractionated stereotactic radiotherapy (FSRT) and single-session stereotactic radiosurgery (SRS) by using 3D quantitative response assessment on MRI. This retrospective analysis included 162 patients who underwent radiation therapy for sporadic VS. Measurements on T1-weighted contrast-enhanced MRI (in 2-year post-therapy intervals: 0-2, 2-4, 4-6, 6-8, 8-10, 10-12 years) were taken for total tumour volume (TTV) and enhancing tumour volume (ETV) based on a semi-automated technique. Patients were considered non-responders (NRs) if they required subsequent microsurgical resection or developed radiological progression and tumour-related symptoms. Median follow-up was 4.1 years (range: 0.4-12.0). TTV and ETV decreased for both the FSRT and SRS groups. However, only the FSRT group achieved significant tumour shrinkage (p < 0.015 for TTV, p < 0.005 for ETV over time). The 11 NRs showed proportionally greater TTV (median TTV pre-treatment: 0.61 cm3, 8-10 years after: 1.77 cm3) and ETV despite radiation therapy compared to responders (median TTV pre-treatment: 1.06 cm3; 10-12 years after: 0.81 cm3; p = 0.001). 3D quantification of VS showed a significant decrease in TTV and ETV on FSRT-treated patients only. NR had significantly greater TTV and ETV over time. (orig.)

  18. Cine Computed Tomography Without Respiratory Surrogate in Planning Stereotactic Radiotherapy for Non-Small-Cell Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: To determine whether cine computed tomography (CT) can serve as an alternative to four-dimensional (4D)-CT by providing tumor motion information and producing equivalent target volumes when used to contour in radiotherapy planning without a respiratory surrogate. Methods and Materials: Cine CT images from a commercial CT scanner were used to form maximum intensity projection and respiratory-averaged CT image sets. These image sets then were used together to define the targets for radiotherapy. Phantoms oscillating under irregular motion were used to assess the differences between contouring using cine CT and 4D-CT. We also retrospectively reviewed the image sets for 26 patients (27 lesions) at our institution who had undergone stereotactic radiotherapy for Stage I non-small-cell lung cancer. The patients were included if the tumor motion was >1 cm. The lesions were first contoured using maximum intensity projection and respiratory-averaged CT image sets processed from cine CT and then with 4D-CT maximum intensity projection and 10-phase image sets. The mean ratios of the volume magnitude were compared with intraobserver variation, the mean centroid shifts were calculated, and the volume overlap was assessed with the normalized Dice similarity coefficient index. Results: The phantom studies demonstrated that cine CT captured a greater extent of irregular tumor motion than did 4D-CT, producing a larger tumor volume. The patient studies demonstrated that the gross tumor defined using cine CT imaging was similar to, or slightly larger than, that defined using 4D-CT. Conclusion: The results of our study have shown that cine CT is a promising alternative to 4D-CT for stereotactic radiotherapy planning

  19. Rotationally acquired four-dimensional optical coherence tomography of embryonic chick hearts using retrospective gating on the common central A-scan

    DEFF Research Database (Denmark)

    Happel, Christoph M.; Thommes, Jan; Thrane, Lars;

    2011-01-01

    We introduce a new method of rotational image acquisition for four-dimensional (4D) optical coherence tomography (OCT) of beating embryonic chick hearts. The rotational axis and the central A-scan of the OCT are identical. An out-of-phase image sequence covering multiple heartbeats is acquired at.......We demonstrate this approach and provide a video of a beating Hamburger and Hamilton stage 16 embryonic chick heart generated from a 4D OCT data set using rotational image acquisition....

  20. Quantum corrections to ward identities of chronological AVV- and AAA-current correlators for nondegenerate many-fermion systems in the four-dimensional world

    International Nuclear Information System (INIS)

    The explicit form of nontrivial quantum corrections to Ward identities for AVV- and AAA-current correlators in the four-dimensional world for nondegenerate many-fermion systems of general type is obtained. The characteristics of all nontrivial quantum corrections for nondegenerate two-flavour fermion systems are classified and described. In particular, the well-known results follow from ours for the trivial quantum corrections (anomalies) in the case of the degenerate spectrum of fermion masses

  1. Correlations of third-trimester hiatal biometry obtained using four-dimensional translabial ultrasonography with the delivery route in nulliparous pregnant women

    OpenAIRE

    Teerayut Temtanakitpaisan; Varisara Chantarasorn; Suvit Bunyavejchevin

    2015-01-01

    Purpose: The goal of this study was to evaluate normal hiatal dimensions in the third trimester in nulliparous Thai pregnant women and to establish which biometric factors were associated with various pregnancy outcomes. Methods: Fifty-seven consecutive nulliparous pregnant Thai women in their third trimester were recruited on a voluntary basis from April to October 2014. All subjects underwent four-dimensional (4D) translabial ultrasonography. Hiatal biometric parameters were measured at res...

  2. To what extent does the anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) detect specific types of anxiety disorder in primary care? A psychometric study

    OpenAIRE

    Terluin, B.; Oosterbaan, D.B.; Brouwers, E.P.M.; van Straten, A.H.M.; Van de Ven, P.; Langerak, W.; van Marwijk, H.W.J.

    2014-01-01

    BACKGROUND: Anxiety scales may help primary care physicians to detect specific anxiety disorders among the many emotionally distressed patients presenting in primary care. The anxiety scale of the Four-Dimensional Symptom Questionnaire (4DSQ) consists of an admixture of symptoms of specific anxiety disorders. The research questions were: (1) Is the anxiety scale unidimensional or multidimensional? (2) To what extent does the anxiety scale detect specific DSM-IV anxiety disorders? (3) Which cu...

  3. TU-F-17A-09: Four-Dimensional Cone Beam CT Ventilation Imaging Can Detect Interfraction Lung Function Variations for Locally Advanced Lung Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Kipritidis, J; Keall, P [Radiation Physics Laboratory, University of Sydney, Sydney NSW 2006 Australia (Australia); Hugo, G; Weiss, E; Williamson, J [Department of Radiation Oncology, Virginia Commonwealth University, Richmond VA (United States)

    2014-06-15

    Purpose: Four-dimensional cone beam CT ventilation imaging (4D-CBCT VI) is a novel functional lung imaging modality requiring validation. We hypothesize that 4D-CBCT VI satisfies a necessary condition for validity: that intrafraction variations (e.g. due to poor 4D-CBCT image quality) are substantially different to interfraction variations (e.g. due to changes in underlying function). We perform the first comparison of intrafraction (pre/post fraction) and interfraction (week-to-week) 4D-CBCT VIs for locally advanced non small cell lung cancer (LA NSCLC) patients undergoing radiation therapy. Methods: A total of 215 4D-CBCT scans were acquired for 19 LA NSCLC patients over 4-6 weeks of radiation therapy, including 75 pairs of pre-/post-fraction scans on the same day. 4D-CBCT VIs were obtained by applying state-of-the-art, B-spline deformable image registration to obtain the Jacobian determinant of deformation between the end-exhale and end-inhale phases. All VIs were deformably registered to the corresponding first day scan, normalized between the 10th and 90th percentile values and cropped to the ipsilateral lung only. Intrafraction variations were assessed by computing the mean and standard deviation of voxel-wise differences between all same-day pairs of pre-/post-fraction VIs. Interfraction differences were computed between first-day VIs and treatment weeks 2, 4 and 6 for all 19 patients. We tested the hypothesis by comparing cumulative distribution functions (CDFs) of intrafraction and interfraction ventilation differences using two-sided Kolmogorov-Smirnov goodness-of-fit tests. Results: The (mean ± std. dev.) of intrafraction differences was (−0.007 ± 0.079). Interfraction differences for weeks 2, 4 and 6 were (−0.035 ± 0.103), (−0.006 ± 0.094) and (−0.019 ± 0.127) respectively. For week 2, the changes in CDFs for intrafraction and interfraction differences approached statistical significance (p=0.099). Conclusion: We have shown that 4D-CBCT VI

  4. New Visualization Techniques to Analyze Ultra-High Resolution Three- and Four-Dimensional Airborne and Tripod LiDAR Point-Cloud Data

    Science.gov (United States)

    Kreylos, O.; Bawden, G. W.; Kellogg, L. H.

    2007-12-01

    In the context of the UC~Davis W. M. Keck Center for Active Visualization in the Earth Sciences (KeckCAVES, http://www.keckcaves.org), we are developing an immersive visualization application to display and interact with very large (billions of points) three- and four-dimensional point-position datasets, such that point groups from repeated airborne and ground based Light Detection And Ranging (LiDAR) surveys can be selected, measured, and analyzed for quality control and land surface change detection. One of the difficulties of analyzing dense 3D and 4D point-cloud data is that there are few software packages that can display and analyze the data at full resolution and in the natural 3D perspective in which it was collected. We developed an octree-based, multiresolution, point-set data representation that allows very large point cloud datasets to be displayed at the frame rates required to create immersion (between 60 Hz and 120 Hz). Data inside an observer's region of interest is shown in full detail, whereas data outside the field of view or far away from the observer is shown at reduced resolution to provide context. Users can navigate LiDAR data sets and accurately select related point groups in two or more point sets by sweeping space using 3D input devices provided by immersive display environments such as CAVEs. Users can then guide the software in deriving positional information from point groups to compute displacements between surveys, or to extract survey measurements. This software runs on UNIX-like operating systems and can be used on laptop or desktop computers, 3D display systems such as Geowalls, and in fully immersive environments such as CAVEs. It is available for download from http://www.keckcaves.org. Examples of the wide range of applications of the software for airborne and Tripod LiDAR (T-LiDAR) include: 1)~visualization of airborne LiDAR data from the southern San Andreas Fault; 2)~quality control assessment of ground based T-LiDAR from the

  5. TU-F-17A-09: Four-Dimensional Cone Beam CT Ventilation Imaging Can Detect Interfraction Lung Function Variations for Locally Advanced Lung Cancer Patients

    International Nuclear Information System (INIS)

    Purpose: Four-dimensional cone beam CT ventilation imaging (4D-CBCT VI) is a novel functional lung imaging modality requiring validation. We hypothesize that 4D-CBCT VI satisfies a necessary condition for validity: that intrafraction variations (e.g. due to poor 4D-CBCT image quality) are substantially different to interfraction variations (e.g. due to changes in underlying function). We perform the first comparison of intrafraction (pre/post fraction) and interfraction (week-to-week) 4D-CBCT VIs for locally advanced non small cell lung cancer (LA NSCLC) patients undergoing radiation therapy. Methods: A total of 215 4D-CBCT scans were acquired for 19 LA NSCLC patients over 4-6 weeks of radiation therapy, including 75 pairs of pre-/post-fraction scans on the same day. 4D-CBCT VIs were obtained by applying state-of-the-art, B-spline deformable image registration to obtain the Jacobian determinant of deformation between the end-exhale and end-inhale phases. All VIs were deformably registered to the corresponding first day scan, normalized between the 10th and 90th percentile values and cropped to the ipsilateral lung only. Intrafraction variations were assessed by computing the mean and standard deviation of voxel-wise differences between all same-day pairs of pre-/post-fraction VIs. Interfraction differences were computed between first-day VIs and treatment weeks 2, 4 and 6 for all 19 patients. We tested the hypothesis by comparing cumulative distribution functions (CDFs) of intrafraction and interfraction ventilation differences using two-sided Kolmogorov-Smirnov goodness-of-fit tests. Results: The (mean ± std. dev.) of intrafraction differences was (−0.007 ± 0.079). Interfraction differences for weeks 2, 4 and 6 were (−0.035 ± 0.103), (−0.006 ± 0.094) and (−0.019 ± 0.127) respectively. For week 2, the changes in CDFs for intrafraction and interfraction differences approached statistical significance (p=0.099). Conclusion: We have shown that 4D-CBCT VI

  6. Advice concerning radiotherapy

    International Nuclear Information System (INIS)

    Dutch National cancer incidence figures were calculated by using the reliable data on cancer incidence in the Eindhoven area and population forecasts and information obtained from the Central Bureau of Statistics. Several radiotherapy departments suffer from under capacity (a lack of resources and understaffing). Data have also shown that 35% of cancer patients receive radiotherapy, instead of 50%. Calculations have been made by the committee on the present and future needs with regard to equipment and staff. In 1983, the number of megavoltage therapy units amounted to 38, but should have been 65. It should be 80 in 1990 and 90 in 2000. Since building and installing such equipment is a lengthy process a considerable effort is needed to make up for the arrears. The committee advocates the extension of the system of regional cooperation in cancer care (comprehensive cancer centres), in which radiotherapy departments play a crucial role. Working parties from the committee provided a comprehensive description of current radiotherapy practice with reference to physical, technical, clinical and management aspects. Another working party assessed the results of cancer treatment with regard to many different tumour sites. Recent and expected developments were analysed or indicated. The Radiotherapy Committee commissioned an external team to conduct a project to achieve a picture of future developments using methods different to those of the committee's. An interim advice has been added on this subject. (Auth.)

  7. Personalized Assessment of kV Cone Beam Computed Tomography Doses in Image-guided Radiotherapy of Pediatric Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yibao [Beijing Key Lab of Medical Physics and Engineering, Peking University, Beijing (China); Yan Yulong [Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (United States); Nath, Ravinder [Department of Therapeutic Radiology, Yale University, New Haven, Connecticut (United States); Bao Shanglian [Beijing Key Lab of Medical Physics and Engineering, Peking University, Beijing (China); Deng Jun, E-mail: jun.deng@yale.edu [Department of Therapeutic Radiology, Yale University, New Haven, Connecticut (United States)

    2012-08-01

    Purpose: To develop a quantitative method for the estimation of kV cone beam computed tomography (kVCBCT) doses in pediatric patients undergoing image-guided radiotherapy. Methods and Materials: Forty-two children were retrospectively analyzed in subgroups of different scanned regions: one group in the head-and-neck and the other group in the pelvis. Critical structures in planning CT images were delineated on an Eclipse treatment planning system before being converted into CT phantoms for Monte Carlo simulations. A benchmarked EGS4 Monte Carlo code was used to calculate three-dimensional dose distributions of kVCBCT scans with full-fan high-quality head or half-fan pelvis protocols predefined by the manufacturer. Based on planning CT images and structures exported in DICOM RT format, occipital-frontal circumferences (OFC) were calculated for head-and-neck patients using DICOMan software. Similarly, hip circumferences (HIP) were acquired for the pelvic group. Correlations between mean organ doses and age, weight, OFC, and HIP values were analyzed with SigmaPlot software suite, where regression performances were analyzed with relative dose differences (RDD) and coefficients of determination (R{sup 2}). Results: kVCBCT-contributed mean doses to all critical structures decreased monotonically with studied parameters, with a steeper decrease in the pelvis than in the head. Empirical functions have been developed for a dose estimation of the major organs at risk in the head and pelvis, respectively. If evaluated with physical parameters other than age, a mean RDD of up to 7.9% was observed for all the structures in our population of 42 patients. Conclusions: kVCBCT doses are highly correlated with patient size. According to this study, weight can be used as a primary index for dose assessment in both head and pelvis scans, while OFC and HIP may serve as secondary indices for dose estimation in corresponding regions. With the proposed empirical functions, it is possible

  8. Assessment of quality of life in patients with rectal cancer treated by preoperative radiotherapy: A longitudinal prospective study

    International Nuclear Information System (INIS)

    Purpose: To assess prospectively the quality of life (QOL) of patients treated by preoperative radiotherapy (RT) and surgery for locally advanced rectal cancer. Methods and materials: We studied 53 patients treated with bi-fractionated RT (50 Gy in 40 fractions within 4 weeks) followed at a median interval of 45 days by abdominoperineal resection in 11 patients and low anterior resection in 42 patients. Their QOL was assessed using two self-rating questionnaires developed by the European Organization for Research and Treatment of Cancer (EORTC): one was cancer specific (EORTC QLQ-C30) and one was site specific (EORTC QLQ-C38). The questionnaires were completed before RT and 12-16 months after RT, at which time 17 patients had undergone colostomy. We hypothesized that at least some scores of the various scales would vary between the two analyses. Results: Compared with the pre-RT scores, at 1 year, patients reported statistically significant improvement in their emotional state (median 75 vs. 100, p <0.0001), perspective of the future (67 vs. 100, p = 0.0004), and their global QOL (75 vs. 83, p = 0.0008), as well as a decrease in GI symptoms (13 vs. 0, p = 0.002). However, the sexual dysfunction score increased significantly, particularly in men (17 vs. 83, p = 0.0045), and a trend toward a lower body image score was observed (100 vs. 89, p = 0.068). At 1 year, patients with colostomies reported similar or significantly improved symptom scores for fatigue, pain, GI problems, and sleep disturbance, but no such improvements were observed in patients without stomas. Conclusion: One year after combined treatment for locally advanced rectal cancer, patients exhibited statistically significant improvement in some important QOL outcomes, including global QOL, despite a decrease in sexual function and body image. Any additional improvement in QOL outcome may require refinements in the RT and surgical techniques to reduce late sequelae, particularly sexual dysfunction. Our

  9. Personalized Assessment of kV Cone Beam Computed Tomography Doses in Image-guided Radiotherapy of Pediatric Cancer Patients

    International Nuclear Information System (INIS)

    Purpose: To develop a quantitative method for the estimation of kV cone beam computed tomography (kVCBCT) doses in pediatric patients undergoing image-guided radiotherapy. Methods and Materials: Forty-two children were retrospectively analyzed in subgroups of different scanned regions: one group in the head-and-neck and the other group in the pelvis. Critical structures in planning CT images were delineated on an Eclipse treatment planning system before being converted into CT phantoms for Monte Carlo simulations. A benchmarked EGS4 Monte Carlo code was used to calculate three-dimensional dose distributions of kVCBCT scans with full-fan high-quality head or half-fan pelvis protocols predefined by the manufacturer. Based on planning CT images and structures exported in DICOM RT format, occipital-frontal circumferences (OFC) were calculated for head-and-neck patients using DICOMan software. Similarly, hip circumferences (HIP) were acquired for the pelvic group. Correlations between mean organ doses and age, weight, OFC, and HIP values were analyzed with SigmaPlot software suite, where regression performances were analyzed with relative dose differences (RDD) and coefficients of determination (R2). Results: kVCBCT-contributed mean doses to all critical structures decreased monotonically with studied parameters, with a steeper decrease in the pelvis than in the head. Empirical functions have been developed for a dose estimation of the major organs at risk in the head and pelvis, respectively. If evaluated with physical parameters other than age, a mean RDD of up to 7.9% was observed for all the structures in our population of 42 patients. Conclusions: kVCBCT doses are highly correlated with patient size. According to this study, weight can be used as a primary index for dose assessment in both head and pelvis scans, while OFC and HIP may serve as secondary indices for dose estimation in corresponding regions. With the proposed empirical functions, it is possible to

  10. Micro-and nanodosimetry for radiobiological planning in radiotherapy and cancer risk assessment in radiation environment

    International Nuclear Information System (INIS)

    Full text: Microdosimetry and nanodosimetry can provide unique information for prediction of radiobiological properties of radiation, which is important in radiation therapy for accurate dose planning and in radiation protection for cancer induction risk assessment. This demand measurements of the pattern of energies deposited by ionizing radiation on cellular scale and DNA levels.Silicon microelectronics technology is offering a unique opportunity for replacing gas proportional counters (TEPC) with miniature detectors for regional microdosimetry. Silicon on Insulator (SOI) technology has been used for the development of arrays of micron size sensitive volumes for modelling energy deposited in biological cells. The challenge in silicon microdosimetry is the development of well defined sensitive volume (SV) and full charge collection deposited by ionizing radiation in the SV. First generation SOI microdosimeters were developed at CMRP and investigated in a wide range of radiation fields for proton and neutron therapies and recently on isotopic neutron sources and heavy ions with energy up to lGeV/jj,m which are typical for deep space radiation environment. Microdosimetric spectra were obtained in a phantom that are well matched to TEPC and Monte Carlo simulations. Evidence that radiations with the same LET exhibit different biological effects demand development of new sensors sensitive to the track structure of ions or the type of particle for prediction of radiobiological effect of radiation using radiobiological models. New monolithic Si AE-E telescope of cellular size for simultaneous regional microdosimetry and particle identification will be presented and results will be discussed. The new design of the SOI microdosimeter is based on 3D micron and submicron size of Si SVs. This approach allows improvement in the accuracy of the Si microdosimetry because of full charge collection and the ability to measure low LET as low as 0.01 keV/jjm, which is similar to TEPC

  11. Assessment of risks of stenosis of the anal canal during a prostatic radiotherapy; evaluation des risques de stenose du canal anal lors de la radiotherapie prostatique

    Energy Technology Data Exchange (ETDEWEB)

    Almokhles, H.; Pan, Q.; Calitchi, E.; Diana, C.; Muresan, M.; Jiang, M.W.; Wu, J.F.; Wang, X.W.; Lu, H.J.; Lagrange, J.L. [Hopital Henri-Mondor, Creteil (France)

    2011-10-15

    The authors report a study which aimed at assessing the late tolerance of a prostatic irradiation at the rectum and anal canal level. They assessed the length of the rectum and of the anal canal after prostate irradiation or surgery in patients who suffered from a prostate adenocarcinoma. Data of 154 patients have been analyzed regarding the number of cases of stenosis of rectum or anal canal. They highlight the importance of the irradiated length and dose level. Short communication

  12. Quality of life assessment in advanced non-small-cell lung cancer patients undergoing an accelerated radiotherapy regimen: report of ECOG study 4593

    International Nuclear Information System (INIS)

    Purpose: To prospectively evaluate the quality of life (QOL) before, at completion, and after therapy for patients receiving an accelerated fractionation schedule of radiotherapy for advanced, unresectable non-small-cell lung cancer in a Phase II multi-institutional trial. Methods and Materials: The Functional Assessment of Cancer Therapy-Lung (FACT-L) patient questionnaire was used to score the QOL in patients enrolled in the Eastern Cooperative Oncology Group Phase II trial (ECOG 4593) of hyperfractionated accelerated radiotherapy in non-small-cell lung cancer. Radiotherapy (total dose 57.6 Gy in 36 fractions) was delivered during 15 days, with three radiation fractions given each treatment day. The protocol was activated in 1993, and 30 patients had accrued by November 1995. The FACT-L questionnaire was administered at study entry (baseline), on the last day of radiotherapy (assessment 2), and 4 weeks after therapy (assessment 3). The FACT-L includes scores for physical, functional, emotional, and social well-being (33 items), and a subscale of lung cancer symptoms (10 additional items). The summation of the physical, functional, and lung cancer symptom subscales (21 items) constitutes the Trial Outcome Index (TOI), considered the most clinically relevant outcome measure in lung cancer treatment trials. Results: The FACT-L completion rates at the designated study time points were as follows: baseline, 30 of 30 (100%); assessment 2, 29 (97%) of 30; and assessment 3, 24 (80%) of 30. At treatment completion, statistically significant declines in QOL scores were noted, compared with baseline for physical and functional well-being. Emotional well-being scores improved at both assessment 2 and assessment 3. The physical and functional scores returned approximately to baseline values at assessment 3. The change in TOI score was evaluated as a function of the clinical response to treatment, toxicity grade, and survival; no clear association was noted. A trend for the

  13. Radiotherapy; Strahlentherapie

    Energy Technology Data Exchange (ETDEWEB)

    Wannenmacher, M. [Heidelberg Univ., Mannheim (Germany). Abt. fuer Klinische Radiologie; Debus, J. [Univ. Heidelberg (Germany). Abt. Radioonkologie und Strahlentherapie; Wenz, F. (eds.) [Universitaetsklinikum Mannheim (Germany). Klinik fuer Strahlentherapie und Radioonkologie

    2006-07-01

    The book is focussed on the actual knowledge on the clinical radiotherapy and radio-oncology. Besides fundamental and general contributions specific organ systems are treated in detail. The book contains the following contributions: Basic principles, radiobiological fundamentals, physical background, radiation pathology, basics and technique of brachytherapy, methodology and technique of the stereotactic radiosurgery, whole-body irradiation, operative radiotherapy, hadron therapy, hpyerthermia, combined radio-chemo-therapy, biometric clinical studies, intensity modulated radiotherapy, side effects, oncological diagnostics; central nervous system and sense organs, head-neck carcinomas, breast cancer, thorax organs, esophagus carcinoma, stomach carcinoma, pancreas carcinoma, heptabiliary cancer and liver metastases, rectal carcinomas, kidney and urinary tract, prostate carcinoma, testicular carcinoma, female pelvis, lymphatic system carcinomas, soft tissue carcinoma, skin cancer, bone metastases, pediatric tumors, nonmalignant diseases, emergency in radio-oncology, supporting therapy, palliative therapy.

  14. Tumor Shrinkage Assessed by Volumetric MRI in Long-Term Follow-Up After Fractionated Stereotactic Radiotherapy of Nonfunctioning Pituitary Adenoma

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Christine, E-mail: Christine.Kopp@lrz.tu-muenchen.de [Klinik und Poliklinik fuer Strahlentherapie und Radiologische Onkologie, Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich (Germany); Theodorou, Marilena; Poullos, Nektarios; Jacob, Vesna; Astner, Sabrina T.; Molls, Michael [Klinik und Poliklinik fuer Strahlentherapie und Radiologische Onkologie, Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich (Germany); Grosu, Anca-Ligia [Klinik fuer Strahlenheilkunde, Universitaet Freiburg, Freiburg (Germany)

    2012-03-01

    Purpose: To evaluate tumor control and side effects associated with fractionated stereotactic radiotherapy (FSRT) in the management of residual or recurrent nonfunctioning pituitary adenomas (NFPAs). Methods and Materials: We assessed exact tumor volume shrinkage in 16 patients with NFPA after FSRT. All patients had previously undergone surgery. Gross tumor volume (GTV) was outlined on contrast-enhanced magnetic resonance imaging (MRI) before and median 63 months (range, 28-100 months) after FSRT. MRI was performed as an axial three-dimensional gradient echo T1-weighted sequence at 1.6-mm slice thickness without gap (3D MRI). Results: Mean tumor size of all 16 pituitary adenomas before treatment was 7.4 mL (3.3-18.9 mL). We found shrinkage of the treated pituitary adenoma in all patients. Within a median follow-up of 63 months (28-100 months) an absolute mean volume reduction of 3.8 mL (0.9-12.4 mL) was seen. The mean relative size reduction compared with the volume before radiotherapy was 51% (22%-95%). Shrinkage measured by 3D MRI was greater at longer time intervals after radiotherapy. A strong negative correlation between the initial tumor volume and the absolute volume reduction after FSRT was found. There was no correlation between tumor size reduction and patient age, sex, or number of previous surgeries. Conclusions: By using 3D MRI in all patients undergoing FSRT of an NFPA, tumor shrinkage is detected. Our data demonstrate that volumetric assessment based on 3D MRI adds additional information to routinely used radiological response measurements. After FSRT a mean relative size reduction of 51% can be expected within 5 years.

  15. Comparison of Physical Examination and Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography 4–6 Months After Radiotherapy to Assess Residual Head-and-Neck Cancer

    International Nuclear Information System (INIS)

    Purpose: To retrospectively compare fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) and physical examination 4–6 months after radiotherapy for assessing residual head-and-neck cancer (HNC). Methods and Materials: From July 2002 through March 2006, 52 HNC patients underwent definitive radiotherapy or chemoradiotherapy. Categoric assessments of residual tumor by PET/CT and physical examination 4–6 months after therapy were correlated and compared with clinical outcomes. Pretreatment data, including tumor stage and primary site standardized uptake value, were also gathered retrospectively and correlated with clinical outcomes. Median follow-up time was 58 months. Results: Twenty-one patients had either locoregionally “positive” (17 of 21) or “equivocal” (4 of 21) PET/CT scans, whereas 31 patients had locoregionally negative scans. Four patients failed treatment and had biopsy-confirmed residual or recurrent local disease. All patients, including patients with locally suspicious scans or examinations who refused biopsies, were followed clinically for a minimum of 29 months after therapy, with no other cases of treatment failure detected during this time. No patient had residual nodal disease after therapy. Sensitivities of PET/CT vs. physical examination for early detection of treatment failure were 100% vs. 50%, whereas the specificities of the two modalities were 64.6% vs. 89.6%, respectively. Higher initial T stage and American Joint Commission on Cancer stage correlated with increased incidence of positive/equivocal PET/CT results and treatment failure. Maximal standardized uptake value was not predictive of any clinical outcome. Conclusions: A negative result on PET/CT obtained 4–6 months after radiotherapy is highly sensitive and correlates with successful locoregional control. Patients with negative scans may reasonably be spared invasive diagnostic procedures, such as biopsy and neck dissection, unless recurrent

  16. Assessment of two novel ventilatory surrogates for use in the delivery of gated/tracked radiotherapy for non-small cell lung cancer

    International Nuclear Information System (INIS)

    Background: In selected patients with NSCLC the therapeutic index of radical radiotherapy can be improved with gating/tracking technology. Both techniques require real-time information on target location. This is often derived from a surrogate ventilatory signal. We assessed the correlation of two novel surrogate ventilatory signals with a spirometer-derived signal. The novel signals were obtained using the VisionRT stereoscopic camera system. The VisionRT-Tracked-Point (VRT-TP) signal was derived from tracking a point located midway between the umbilicus and xiphisternum. The VisionRT-Surface-Derived-Volume (VRT-SDV) signal was derived from 3D body surface imaging of the torso. Both have potential advantages over the current surrogate signals. Methods: Eleven subjects with NSCLC were recruited. Each was positioned as for radiotherapy treatment, and then instructed to breathe in five different modes: normal, abdominal, thoracic, deep and shallow breathing. Synchronous ventilatory signals were recorded for later analysis. The signals were analysed for correlation across all modes of breathing, and phase shifts. The VRT-SDV was also assessed for its ability to determine the mode of breathing. Results: Both novel respiratory signals showed good correlation (r > 0.80) with spirometry in 9 of 11 subjects. For all subjects the correlation with spirometry was better for the VRT-SDV signal than for the VRT-TP signal. Only one subject displayed a phase shift between the VisionRT-derived signals and spirometry. The VRT-SDV signal could also differentiate between different modes of breathing. Unlike the spirometer-derived signal, neither VisionRT-derived signal was subject to drift. Conclusion: Both the VRT-TP and VRT-SDV signals have potential applications in ventilatory-gated and tracked radiotherapy. They can also be used as a signal for sorting 4DCT images, and to drive 4DCT single- and multiple-parameter motion models.

  17. Tumor Shrinkage Assessed by Volumetric MRI in Long-Term Follow-Up After Fractionated Stereotactic Radiotherapy of Nonfunctioning Pituitary Adenoma

    International Nuclear Information System (INIS)

    Purpose: To evaluate tumor control and side effects associated with fractionated stereotactic radiotherapy (FSRT) in the management of residual or recurrent nonfunctioning pituitary adenomas (NFPAs). Methods and Materials: We assessed exact tumor volume shrinkage in 16 patients with NFPA after FSRT. All patients had previously undergone surgery. Gross tumor volume (GTV) was outlined on contrast-enhanced magnetic resonance imaging (MRI) before and median 63 months (range, 28–100 months) after FSRT. MRI was performed as an axial three-dimensional gradient echo T1-weighted sequence at 1.6-mm slice thickness without gap (3D MRI). Results: Mean tumor size of all 16 pituitary adenomas before treatment was 7.4 mL (3.3–18.9 mL). We found shrinkage of the treated pituitary adenoma in all patients. Within a median follow-up of 63 months (28–100 months) an absolute mean volume reduction of 3.8 mL (0.9–12.4 mL) was seen. The mean relative size reduction compared with the volume before radiotherapy was 51% (22%–95%). Shrinkage measured by 3D MRI was greater at longer time intervals after radiotherapy. A strong negative correlation between the initial tumor volume and the absolute volume reduction after FSRT was found. There was no correlation between tumor size reduction and patient age, sex, or number of previous surgeries. Conclusions: By using 3D MRI in all patients undergoing FSRT of an NFPA, tumor shrinkage is detected. Our data demonstrate that volumetric assessment based on 3D MRI adds additional information to routinely used radiological response measurements. After FSRT a mean relative size reduction of 51% can be expected within 5 years.

  18. Application of alanine dosimetry in dose assessment for ocular melanoma patients undergoing proton radiotherapy – preliminary results

    Directory of Open Access Journals (Sweden)

    Mierzwińska Gabriela

    2015-09-01

    Full Text Available Basing on alanine solid state/electron paramagnetic resonance (EPR dosimetry, a supplementary method of cumulatively recording the therapeutic dose received by ocular cancer patients undergoing fractionated proton radiotherapy is proposed. By applying alanine dosimetry during the delivery of consecutive fractions, the dose received within each fraction can be read out by EPR spectrometry and a final permanent cumulative record of the total dose delivered obtained. The dose response of the alanine detector was found to be practically independent on its position within the extended proton Bragg peak region. Dose measurements based on entrance dose recorded in proton beams individually formed for each patient are presented. The described method will be applied as a complementary Quality Assurance procedure for patients undergoing proton radiotherapy at the Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland (IFJ PAN.

  19. Comparative study and clinical implementation of two breathing-adapted radiotherapy techniques: dosimetric benefits for lung cancer treatment; Etude comparative et mise en oeuvre clinique de deux systemes de radiotherapie asservie a la respiration: benefice dosimetrique pour le traitement du cancer du poumon

    Energy Technology Data Exchange (ETDEWEB)

    Simon, L.; Giraud, P.; Rosenwald, J.C. [Institut Curie, Dept. de Radiotherapie, 75 - Paris (France); Servois, V. [Institut Curie, Dept. d' Imagerie Medicale, 75 - Paris (France)

    2006-11-15

    Breathing can lead to organ motions up to several centimeters. For radiotherapy of lung, these motions are generally taken into account by adding a specific margin around the target. Thus, treated volumes are often too large to allow for the high-dose values requested for local control. To manage respiratory motion, deep-inspiration breath-hold technique (DIBH) and gated radiotherapy are starting being used clinically. DIBH consists in asking the patient to perform breath-hold during the treatment and the image acquisition, DIBH level being measured by a spirometer. Gated radiotherapy consists in treating the patient at a certain phase of the free breathing. Linac is synchronized with the motion of a marker' located on the patient chest. Planning images are obtained by a four-dimensional CT (4D-CT) using the same marker. We have assessed the value of these two methods. For lung treatment, compared to a standard treatment, toxicity reduction was mainly due to the lung total volume increase.; It is therefore more significant for breath-hold approach. It is also due to the reduction of safety margins, which is similar for both methods. These two techniques, which have specific advantages and drawbacks, are used routinely at Curie Institute for a large proportion of lung patients, but also for some breast, liver or even Hodgkin disease treatments. (author)

  20. Quality improvement process to assess tattoo alignment, set-up accuracy and isocentre reproducibility in pelvic radiotherapy patients

    OpenAIRE

    Elsner, Kelly; Francis, Kate; Hruby, George; Roderick, Stephanie

    2014-01-01

    Introduction This quality improvement study tested three methods of tattoo alignment and isocentre definition to investigate if aligning lateral tattoos to minimise pitch, roll and yaw decreased set-up error, and if defining the isocentre using the lateral tattoos for cranio-caudal (CC) position improved isocentre reproducibility. The study population was patients receiving curative external beam radiotherapy (EBRT) for prostate cancer. The results are applicable to all supine pelvic EBRT pat...

  1. Quality indicators in radiotherapy

    International Nuclear Information System (INIS)

    Background and purpose: There is a widespread and increasing tendency to develop hospital performance indicators in the field of accreditation/certification systems and quality benchmarking. A study has been undertaken to develop a set of performance indicators for a typical radiotherapy Centre and to evaluate their ability to provide a continuous quality improvement. Materials and methods: A working group consisting of radiation oncologists, medical physicists and radiation technologists under the coordination of experts in health technology assessment has elaborated a set of general indicators able to monitor performances and the quality level of a typical radiotherapy Centre. The work has been carried out through four steps: a preliminary set of indicators was selected; data on these indicators were collected in a number of Italian radiotherapy Centres and medical physics Services; problems in collection and analysis of data were discussed; a final set of indicators was developed. Results: A final set of 13 indicators is here presented. They concern general structural and/or operational features, health physics activities and accuracy and technical complexity of the treatment. Conclusions: The indicators tested in a few Italian Centres of radiotherapy and medical physics Services are now ready to be utilized by a larger community

  2. Nonlinear spatio-temporal filtering of dynamic PET data using a four-dimensional Gaussian filter and expectation-maximization deconvolution

    International Nuclear Information System (INIS)

    We introduce a method for denoising dynamic PET data, spatio-temporal expectation-maximization (STEM) filtering, that combines four-dimensional Gaussian filtering with EM deconvolution. The initial Gaussian filter suppresses noise at a broad range of spatial and temporal frequencies and EM deconvolution quickly restores the frequencies most important to the signal. We aim to demonstrate that STEM filtering can improve variance in both individual time frames and in parametric images without introducing significant bias. We evaluate STEM filtering with a dynamic phantom study, and with simulated and human dynamic PET studies of a tracer with reversible binding behaviour, [C-11]raclopride, and a tracer with irreversible binding behaviour, [F-18]FDOPA. STEM filtering is compared to a number of established three and four-dimensional denoising methods. STEM filtering provides substantial improvements in variance in both individual time frames and in parametric images generated with a number of kinetic analysis techniques while introducing little bias. STEM filtering does bias early frames, but this does not affect quantitative parameter estimates. STEM filtering is shown to be superior to the other simple denoising methods studied. STEM filtering is a simple and effective denoising method that could be valuable for a wide range of dynamic PET applications. (paper)

  3. Continuous table acquisition MRI for radiotherapy treatment planning: Distortion assessment with a new extended 3D volumetric phantom

    International Nuclear Information System (INIS)

    Purpose: Accurate geometry is required for radiotherapy treatment planning (RTP). When considering the use of magnetic resonance imaging (MRI) for RTP, geometric distortions observed in the acquired images should be considered. While scanner technology and vendor supplied correction algorithms provide some correction, large distortions are still present in images, even when considering considerably smaller scan lengths than those typically acquired with CT in conventional RTP. This study investigates MRI acquisition with a moving table compared with static scans for potential geometric benefits for RTP. Methods: A full field of view (FOV) phantom (diameter 500 mm; length 513 mm) was developed for measuring geometric distortions in MR images over volumes pertinent to RTP. The phantom consisted of layers of refined plastic within which vitamin E capsules were inserted. The phantom was scanned on CT to provide the geometric gold standard and on MRI, with differences in capsule location determining the distortion. MRI images were acquired with two techniques. For the first method, standard static table acquisitions were considered. Both 2D and 3D acquisition techniques were investigated. With the second technique, images were acquired with a moving table. The same sequence was acquired with a static table and then with table speeds of 1.1 mm/s and 2 mm/s. All of the MR images acquired were registered to the CT dataset using a deformable B-spline registration with the resulting deformation fields providing the distortion information for each acquisition. Results: MR images acquired with the moving table enabled imaging of the whole phantom length while images acquired with a static table were only able to image 50%–70% of the phantom length of 513 mm. Maximum distortion values were reduced across a larger volume when imaging with a moving table. Increased table speed resulted in a larger contribution of distortion from gradient nonlinearities in the through

  4. Continuous table acquisition MRI for radiotherapy treatment planning: Distortion assessment with a new extended 3D volumetric phantom

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Amy, E-mail: aw554@uowmail.edu.au; Metcalfe, Peter [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia and Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170 (Australia); Liney, Gary [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia); Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170 (Australia); South West Clinical School, University of New South Wales, Sydney, NSW 2170 (Australia); Holloway, Lois [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia); Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170 (Australia); South West Clinical School, University of New South Wales, Sydney, NSW 2170 (Australia); Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Dowling, Jason; Rivest-Henault, David [Commonwealth Scientific and Industrial Research Organisation, Australian E-Health Research Centre, Herston, QLD 4029 (Australia)

    2015-04-15

    Purpose: Accurate geometry is required for radiotherapy treatment planning (RTP). When considering the use of magnetic resonance imaging (MRI) for RTP, geometric distortions observed in the acquired images should be considered. While scanner technology and vendor supplied correction algorithms provide some correction, large distortions are still present in images, even when considering considerably smaller scan lengths than those typically acquired with CT in conventional RTP. This study investigates MRI acquisition with a moving table compared with static scans for potential geometric benefits for RTP. Methods: A full field of view (FOV) phantom (diameter 500 mm; length 513 mm) was developed for measuring geometric distortions in MR images over volumes pertinent to RTP. The phantom consisted of layers of refined plastic within which vitamin E capsules were inserted. The phantom was scanned on CT to provide the geometric gold standard and on MRI, with differences in capsule location determining the distortion. MRI images were acquired with two techniques. For the first method, standard static table acquisitions were considered. Both 2D and 3D acquisition techniques were investigated. With the second technique, images were acquired with a moving table. The same sequence was acquired with a static table and then with table speeds of 1.1 mm/s and 2 mm/s. All of the MR images acquired were registered to the CT dataset using a deformable B-spline registration with the resulting deformation fields providing the distortion information for each acquisition. Results: MR images acquired with the moving table enabled imaging of the whole phantom length while images acquired with a static table were only able to image 50%–70% of the phantom length of 513 mm. Maximum distortion values were reduced across a larger volume when imaging with a moving table. Increased table speed resulted in a larger contribution of distortion from gradient nonlinearities in the through

  5. Radiotherapy in a public health

    International Nuclear Information System (INIS)

    The aim of our publication is to evaluate the state of radiotherapy, its role and place in oncology and in the public health system, in order to plan necessities. The cost and economical effectiveness are objectives of the current evaluation. Radiotherapy is strongly dependant of introducing new technologies and the need of gross capital investments. However, their relative cost is reduced due to their long-term use. Because of the serious delay of Bulgaria from the world standards in radiotherapy, the analysis is based on the data published in the scientific literature. The main tendencies and ideas for development are based on the analysis of The Swedish Council on Technology Assessment in Health Care (SBU) and the ESTRO QUARTS project. We use Swedish model for estimating the expenses, having in mind the conditions in Bulgaria (salary, management, patient cares). The main conclusions are: 1) Radiotherapy is basic curative and palliative method in oncology; 2) Bulgarian radiotherapy is at one of the last places in Europe (therapeutic units are 30 years old average, despite their recommended exploitation of 12-20 years); 3) In contradiction to the world tendencies delay grows during the last 10 years; 4) In countries with low or average GDP radiotherapy should be prioritized, due to its low cost in comparison to the other treatment methods in oncology; 5) The need of radiotherapy will continue to grow, this necessitate not only replacement of the old machines but increasing their number 3 times during the next few years; 6) It is necessary to form a modern radiotherapy centers, equipped with at least two compatible units, based on the currently existing radiotherapy departments. (authors)

  6. Evaluation of novel radiotherapy technologies: what evidence is needed to assess their clinical and cost effectiveness, and how should we get it?

    NARCIS (Netherlands)

    Loon, J. van; Grutters, J.P.C.; Macbeth, F.

    2012-01-01

    Technical innovations in radiation oncology--eg, intensity-modulated radiotherapy, stereotactic radiotherapy, and particle therapy--can be developed rapidly and introduced into the clinic even when costs associated with their use are much higher than those for conventional radiotherapy. Although cli

  7. Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Nikolaj K. G., E-mail: nkyj@regionsjaelland.dk [Physics and Engineering, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Stewart, Errol [Radiology, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Imaging Research Lab, Robarts Research Institute, London, Ontario N6A 5B7 (Canada); Imaging Program, Lawson Health Research Institute, London, Ontario N6C 2R5 (Canada); Lock, Michael; Fisher, Barbara [Radiation Oncology, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Kozak, Roman [Radiology, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Chen, Jeff [Physics and Engineering, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada); Lee, Ting-Yim [Radiology, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Imaging Research Lab, Robarts Research Institute, London, Ontario N6A 5B7 (Canada); Imaging Program, Lawson Health Research Institute, London, Ontario N6C 2R5 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada); Wong, Eugene [Physics and Engineering, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada); Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

    2014-05-15

    Purpose: Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy. Methods: Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registered to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma. Results: In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast. Conclusions: Based on the authors’ animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT.

  8. Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

    International Nuclear Information System (INIS)

    Purpose: Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy. Methods: Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registered to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma. Results: In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast. Conclusions: Based on the authors’ animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT

  9. Is it possible to improve radiotherapy team members’ communication skills? A randomized study assessing the efficacy of a 38-h communication skills training program

    International Nuclear Information System (INIS)

    Background and purpose: Optimizing communication between radiotherapy team members and patients and between colleagues requires training. This study applies a randomized controlled design to assess the efficacy of a 38-h communication skills training program. Material and methods: Four radiotherapy teams were randomly assigned either to a training program or to a waiting list. Team members’ communication skills and their self-efficacy to communicate in the context of an encounter with a simulated patient were the primary endpoints. These encounters were scheduled at the baseline and after training for the training group, and at the baseline and four months later for the waiting list group. Encounters were audiotaped and transcribed. Transcripts were analyzed with content analysis software (LaComm) and by an independent rater. Results: Eighty team members were included in the study. Compared to untrained team members, trained team members used more turns of speech with content oriented toward available resources in the team (relative rate [RR] = 1.38; p = 0.023), more assessment utterances (RR = 1.69; p < 0.001), more empathy (RR = 4.05; p = 0.037), more negotiation (RR = 2.34; p = 0.021) and more emotional words (RR = 1.32; p = 0.030), and their self-efficacy to communicate increased (p = 0.024 and p = 0.008, respectively). Conclusions: The training program was effective in improving team members’ communication skills and their self-efficacy to communicate in the context of an encounter with a simulated patient. Future study should assess the effect of this training program on communication with actual patients and their satisfaction. Moreover a cost-benefit analysis is needed, before implementing such an intensive training program on a broader scale

  10. Utility of SPECT Lung Perfusion Scans in Assessing the Early Changes in Pulmonary Function after Radiotherapy for Patients with Lung Cancer

    Institute of Scientific and Technical Information of China (English)

    Wenjie Zhang; Rong Zheng; Luiun Zhao; Luhua Wang; Shengzu Chen

    2005-01-01

    OBJECTIVE Radiation-induced lung injury commonly follows radiotherapy (RT) fortumors within and near the thorax. Lung function is usually measured by pulmonary function tests (PFTs). But RT-induced regional changes of pulmonary function cannot be accurately evaluated by PFTs. Lung perfusion scintigraphy compared with other radiographic methods can assess well regional pulmonary physiological function, and a 3-dimensional conformal radiotherapy planning system can quantitatively calculate irradiation dosage. The purpose of this study is to assess, by lung perfusion scintigraphy, early changes in the pulmonary function of patients with lung cancer when receiving thoracic 3-dimensional conformal radiotherapy (3D-CRT).METHODS Nineteen patients receiving thoracic 3D-CRT for lung cancer were studied. A single photon emission computed tomography (SPECT)lung perfusion scan, X-ray or CT scan before RT and after 40~50Gy radiation were performed. Pre-RT SPECT lung perfusion images were classified by comparing lung perfusion defects with radiological abnormalities before RT. Grade 0: There was no lung perfusion defect in the area of radiological abnormality. Grade 1: The size of the radiological abnormality was similar to the area of the lung perfusion defect. Grade 2: The area of the lung perfusion defect was bigger than the size of the radiological abnormality and extended to one lobe of the lung. Grade 3: The area of lung perfusion defect exceeded one lobe of the lung. The radiation field with more than 20 Gy was drawn as a region of interest (ROI). The proportion of radioactive dose within this ROI relative to total lung dose in one slice was calculated.RESULTS All patients had lung perfusion defects, nine patients with grade 1,five patients with grade 2 and five patients with grade 3 damage,respectively. All tumors in the 19 patients were reduced in CT or X-ray images to various degrees after 40~50 Gy radiation. The mean proportion of ROI in 19 patients was 53.7±29

  11. Palliative Radiotherapy

    International Nuclear Information System (INIS)

    Palliative care does not attempt to prolong survival but to the achieve the highest quality of life both for the patient and their family covering their physical, psychological, social and spiritual needs. Radiotherapy (RT), one of the most important therapeutic modalities, has a great significance in palliative medicine for cancer since it attempts to reduce as much as possible the acute reaction associated with the treatment for the patient. (Author)

  12. Vocal cord dysfunction diagnosed by four-dimensional dynamic volume computed tomography in patients with difficult-to-treat asthma: A case series.

    Science.gov (United States)

    Cheng, Wei-Tso; Chen, Huan-Wen; Su, I-Hao; Fang, Ji-Tseng; Kuo, Han-Pin; Huang, Chien-Da

    2015-12-01

    Patients with asthma may also have vocal cord dysfunction (VCD), which leads to poor control of the asthma. Once patients are diagnosed with difficult-to-treat asthma with poor control, VCD should be excluded or treated accordingly. The gold standard for diagnosis of VCD is to perform a laryngoscopy. However, this procedure is invasive and may not be suitable for patients with difficult-to-treat asthma. Four-dimensional (4D) dynamic volume computed tomography (CT) is a noninvasive method for quantification of laryngeal movement, and can serve as an alternative for the diagnosis of VCD. Herein, we present a series of five cases with difficult-to-treat asthma patients who were diagnosed with VCD by 4D dynamic volume CT. Clinicians should be alert to the possibility of VCD when poor control is noted in patients with asthma. Early diagnosis by noninvasive 4D dynamic volume CT can decrease excessive doses of inhaled corticosteroids. PMID:24246257

  13. Assessment of three-dimensional set-up errors in conventional head and neck radiotherapy using electronic portal imaging device

    International Nuclear Information System (INIS)

    Set-up errors are an inherent part of radiation treatment process. Coverage of target volume is a direct function of set-up margins, which should be optimized to prevent inadvertent irradiation of adjacent normal tissues. The aim of this study was to evaluate three-dimensional (3D) set-up errors and propose optimum margins for target volume coverage in head and neck radiotherapy. The dataset consisted of 93 pairs of orthogonal simulator and corresponding portal images on which 558 point positions were measured to calculate translational displacement in 25 patients undergoing conventional head and neck radiotherapy with antero-lateral wedge pair technique. Mean displacements, population systematic (Σ) and random (σ) errors and 3D vector of displacement was calculated. Set-up margins were calculated using published margin recipes. The mean displacement in antero-posterior (AP), medio-lateral (ML) and supero-inferior (SI) direction was -0.25 mm (-6.50 to +7.70 mm), -0.48 mm (-5.50 to +7.80 mm) and +0.45 mm (-7.30 to +7.40 mm) respectively. Ninety three percent of the displacements were within 5 mm in all three cardinal directions. Population systematic (Σ) and random errors (σ) were 0.96, 0.98 and 1.20 mm and 1.94, 1.97 and 2.48 mm in AP, ML and SI direction respectively. The mean 3D vector of displacement was 3.84 cm. Using van Herk's formula, the clinical target volume to planning target volume margins were 3.76, 3.83 and 4.74 mm in AP, ML and SI direction respectively. The present study report compares well with published set-up error data relevant to head and neck radiotherapy practice. The set-up margins were <5 mm in all directions. Caution is warranted against adopting generic margin recipes as different margin generating recipes lead to a different probability of target volume coverage

  14. Qualitative interpretation of PET scans using a Likert scale to assess neck node response to radiotherapy in head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Sjoevall, Johanna; Wahlberg, Peter [Lund University, Department of Otorhinolaryngology (ORL)-Head and Neck Surgery, Skane University Hospital, Lund (Sweden); Bitzen, Ulrika [Lund University, Department of Clinical Physiology and Nuclear Medicine, Skane University Hospital, Lund (Sweden); Kjellen, Elisabeth; Nilsson, Per; Brun, Eva [Lund University, Department of Oncology and Radiation Physics, Skane University Hospital, Lund (Sweden)

    2016-04-15

    The aim of this study was to determine whether PET scans after radiotherapy (RT), visually interpreted as equivocal regarding metabolic neck node response can be used to accurately categorize patients as responders or nonresponders using a Likert scale and/or maximum standardized uptake value (SUVmax). Other aims were to determine the performance of different methods for assessing post-RT PET scans (visual inspection, a Likert scale and SUVmax) and to establish whether any method is superior in predicting regional control (RC) and overall survival (OS). In 105 patients with neck node-positive head and neck cancer, the neck node response was evaluated by FDG PET/CT 6 weeks after RT. The scans were clinically assessed by visual inspection and, for the purposes of this analysis, re-evaluated using the Deauville criteria, a five-point Likert scale previously used in lymphoma studies. In addition, SUVmax was determined. All assessment methods were able to significantly predict RC but not OS. The methods were also able to significantly predict remission of tumour after completion of RT. Of the 105 PET scans, 19 were judged as equivocal on visual inspection. The Likert scale was preferable to SUVmax for grouping patients as responders or nonresponders. All methods (visual inspection, SUVmax and the Likert scale) identified responders and nonresponders and predicted RC. A Likert scale is a promising tool to reduce to a minimum the problem of PET scans judged as equivocal. Consensus regarding qualitative assessment would facilitate PET reporting in clinical practice. (orig.)

  15. Brady-tachycardia syndrome after radiotherapy for lung cancer. Assessment by computed tomography and carbon-11 methionine positron emission tomography

    International Nuclear Information System (INIS)

    A 74-year-old male who had received radiotherapy (total 54 Gy) for right lung cancer 7 months earlier developed a symptomatic brady-tachycardia syndrome requiring the implantation of a permanent pacemaker. Chest CT showed a pulmonary tumor of 2-cm diameter in the right lower lobe with direct extension into the surrounding tissue, suggesting the possibility of cardiac invasion. Carbon-11 methionine positron emission tomography (PET) indicated the absence of visible invasion of the heart with lung cancer. The brady-tachycardia syndrome, therefore, was considered to be associated with sinus node injury due to radiation. Carbon-11 methionine PET metabolic imaging might play an important role in evaluating noninvasively the cause of the arrhythmia in this patient. (author)

  16. Prospective Assessment of Optimal Individual Position (Prone Versus Supine) for Breast Radiotherapy: Volumetric and Dosimetric Correlations in 100 Patients

    Energy Technology Data Exchange (ETDEWEB)

    Lymberis, Stella C.; Wyngaert, John Keith de; Parhar, Preeti; Chhabra, Arpit M.; Fenton-Kerimian, Maria; Chang Jengwha [Department of Radiation Oncology, New York University School of Medicine and Langone Medical Center, New York, New York (United States); Hochman, Tsivia [Division of Biostatistics, New York University School of Medicine and Langone Medical Center, New York, New York (United States); Department of Environmental Medicine, New York University School of Medicine and Langone Medical Center, New York, New York (United States); Guth, Amber; Roses, Daniel [Department of Surgery, New York University School of Medicine and Langone Medical Center, New York, New York (United States); Goldberg, Judith D. [Division of Biostatistics, New York University School of Medicine and Langone Medical Center, New York, New York (United States); Department of Environmental Medicine, New York University School of Medicine and Langone Medical Center, New York, New York (United States); Formenti, Silvia C., E-mail: silvia.formenti@nyumc.org [Department of Radiation Oncology, New York University School of Medicine and Langone Medical Center, New York, New York (United States)

    2012-11-15

    Purpose: Damage to heart and lung from breast radiotherapy is associated with increased cardiovascular mortality and lung cancer development. We conducted a prospective study to evaluate which position is best to spare lung and heart from radiotherapy exposure. Methods and Materials: One hundred consecutive Stage 0-IIA breast cancer patients consented to participate in a research trial that required two computed tomography simulation scans for planning both supine and prone positions. The optimal position was defined as that which best covered the contoured breast and tumor bed while it minimized critical organ irradiation, as quantified by the in-field heart and lung volume. The trial was designed to plan the first 100 patients in each position to study correlations between in-field volumes of organs at risk and dose. Results: Fifty-three left and 47 right breast cancer patients were consecutively accrued to the trial. In all patients, the prone position was optimal for sparing lung volume compared to the supine setup (mean lung volume reduction was 93.5 cc for right and 103.6 cc for left breast cancer patients). In 46/53 (87%) left breast cancer patients best treated prone, in-field heart volume was reduced by a mean of 12 cc and by 1.8 cc for the other 7/53 (13%) patients best treated supine. As predicted, supine-prone differences in in-field volume and mean dose of heart and lung were highly correlated (Spearman's correlation coefficient for left breast cancer patients was 0.90 for heart and 0.94 for lung and 0.92 for right breast cancer patients for lung). Conclusions: Prone setup reduced the amount of irradiated lung in all patients and reduced the amount of heart volume irradiated in 87% of left breast cancer patients. In-field organ volume is a valid surrogate for predicting dose; the trial continued to the planned target of 400.

  17. Prospective Assessment of Optimal Individual Position (Prone Versus Supine) for Breast Radiotherapy: Volumetric and Dosimetric Correlations in 100 Patients

    International Nuclear Information System (INIS)

    Purpose: Damage to heart and lung from breast radiotherapy is associated with increased cardiovascular mortality and lung cancer development. We conducted a prospective study to evaluate which position is best to spare lung and heart from radiotherapy exposure. Methods and Materials: One hundred consecutive Stage 0–IIA breast cancer patients consented to participate in a research trial that required two computed tomography simulation scans for planning both supine and prone positions. The optimal position was defined as that which best covered the contoured breast and tumor bed while it minimized critical organ irradiation, as quantified by the in-field heart and lung volume. The trial was designed to plan the first 100 patients in each position to study correlations between in-field volumes of organs at risk and dose. Results: Fifty-three left and 47 right breast cancer patients were consecutively accrued to the trial. In all patients, the prone position was optimal for sparing lung volume compared to the supine setup (mean lung volume reduction was 93.5 cc for right and 103.6 cc for left breast cancer patients). In 46/53 (87%) left breast cancer patients best treated prone, in-field heart volume was reduced by a mean of 12 cc and by 1.8 cc for the other 7/53 (13%) patients best treated supine. As predicted, supine-prone differences in in-field volume and mean dose of heart and lung were highly correlated (Spearman's correlation coefficient for left breast cancer patients was 0.90 for heart and 0.94 for lung and 0.92 for right breast cancer patients for lung). Conclusions: Prone setup reduced the amount of irradiated lung in all patients and reduced the amount of heart volume irradiated in 87% of left breast cancer patients. In-field organ volume is a valid surrogate for predicting dose; the trial continued to the planned target of 400.

  18. Postmastectomy radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Shikama, Naoto; Koguchi, Masahiko; Sasaki, Shigeru; Kaneko, Tomoki; Shinoda, Atsunori; Nishikawa, Atsushi [Shinshu Univ., Matsumoto, Nagano (Japan). School of Medicine

    2000-10-01

    Since there have been few reports on postmastectomy radiotherapy having a high evidence level in Japan, the significance of postoperative radiotherapy and the irradiation techniques were reviewed based on reports from Western countries. Authors focused on the indications for postoperative irradiation, irradiation methods (irradiation sites, irradiation techniques; prosthetics, methods of irradiating the chest wall and lymph nodes, timing of irradiation), and complications, and discuss them. The factors thought to be adaptable to postmastectomy radiotherapy have been listed. Axillary lymph node metastasis and the size of the primary focus are thought to be important factors in locoregional recurrence. The chest wall and the supraclavicular lymph nodes are the usual sites of irradiation after mastectomy. The irradiation method consists of tangential irradiation of the chest wall and single-field irradiation of the supraclavicular lymph nodes, with 46-50 Gy in fractional doses of 1.8-2 Gy x 5/w is administered for 4.5-5.5 weeks. The timing of irradiation in the West is generally after chemotherapy. Adverse radiation effects include ischemic heart disease, pneumonitis, arm edema, rib fractures, and brachial plexus paralysis. The frequency of these complications is increased by the combined use of chemotherapy or surgery. The breast cancer cure rate in Japan is generally better than in the West. It remains to be determined whether the clinical data from Europe and America are applicable to the treatment of breast cancer in Japan. To address this issue, a clinical investigation should be performed in Japan with close cooperation between surgeons, physicians, pathologists, and radiotherapists. (K.H.)

  19. Implications of free breathing motion assessed by 4D-computed tomography on the delivered dose in radiotherapy for esophageal cancer.

    Science.gov (United States)

    Duma, Marciana Nona; Berndt, Johannes; Rondak, Ina-Christine; Devecka, Michal; Wilkens, Jan J; Geinitz, Hans; Combs, Stephanie Elisabeth; Oechsner, Markus

    2015-01-01

    The aim of this study was to assess the effect of breathing motion on the delivered dose in esophageal cancer 3-dimensional (3D)-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). We assessed 16 patients with esophageal cancer. All patients underwent 4D-computed tomography (4D-CT) for treatment planning. For each of the analyzed patients, 1 3D-CRT, 1 IMRT, and 1 VMAT (RapidArc-RA) plan were calculated. Each of the 3 initial plans was recalculated on the 4D-CT (for the maximum free inspiration and maximum free expiration) to assess the effect of breathing motion. We assessed the minimum dose (Dmin) and mean dose (Dmean) to the esophagus within the planning target volume, the volume changes of the lungs, the Dmean and the total lung volume receiving at least 40Gy (V40), and the V30, V20, V10, and V5. For the heart we assessed the Dmean and the V25. Over all techniques and all patients the change in Dmean as compared with the planned Dmean (planning CT [PCT]) to the esophagus was 0.48% in maximum free inspiration (CT_insp) and 0.55% in maximum free expiration (CT_exp). The Dmin CT_insp change was 0.86% and CT_exp change was 0.89%. The Dmean change of the lungs (heart) was in CT_insp 1.95% (2.89%) and 3.88% (2.38%) in CT_exp. In all, 4 patients had a clinically relevant change of the dose (≥ 5% Dmean to the heart and the lungs) between inspiration and expiration. These patients had a very cranially or caudally situated tumor. There are no relevant differences in the delivered dose to the regions of interest among the 3 techniques. Breathing motion management could be considered to achieve a better sparing of the lungs or heart in patients with cranially or caudally situated tumors. PMID:26419857

  20. Proxy assessment of patients before and after radiotherapy for brain metastases. Results of a prospective study using the DEGRO brain module

    International Nuclear Information System (INIS)

    Purpose: Proxies of patients with poor performance status could give useful information about the patients' quality of life (QoL). We applied a newly developed questionnaire in a prospective QoL study of patients undergoing radiotherapy for brain metastases in order to make the first move to validate this instrument, and we compared the results with scores obtained using validated patient-completed instruments. Materials and methods: From January 2007 to June 2010, 166 patients with previously untreated brain metastases were recruited at 14 centers in Germany and Austria. The EORTC-QLQ-C15-PAL and the brain module BN20 were used to assess QoL in patients at the start of treatment and 3 months later. At the same time points, 141 of their proxies estimated the QoL with the new DEGRO brain module (DBM), a ten-item questionnaire rating the general condition as well as functions and impairment by symptoms in areas relevant to patients with brain metastases. Results: At 3 months, 85 of 141 patients (60%) with initial response by a proxy were alive. Sixty-seven of these patients (79% of 3-month survivors) and 65 proxies completed the second set of questionnaires. After 3 months, QoL significantly deteriorated in all items of proxy-assessed QoL except headache. Correlations between self-assessed and proxy-assessed QoL were high in single items such as nausea, headache, and fatigue. Conclusions: The high correlation between self-assessment and proxy ratings as well as a similar change over time for both approaches suggest that in patients with brain metastases, proxy assessment using the DBM questionnaire can be an alternative approach to obtaining QoL data when patients are unable to complete questionnaires themselves. Our self-constructed and first applied DBM is the only highly specific instrument for patients with brain metastases, but further tests are needed for its final validation. (orig.)

  1. Proxy assessment of patients before and after radiotherapy for brain metastases. Results of a prospective study using the DEGRO brain module

    Energy Technology Data Exchange (ETDEWEB)

    Steinmann, D. [Medical School Hannover (Germany). Dept. of Radiation Oncology; Vordermark, D. [Halle-Wittenberg Univ. (Germany). Dept. of Radiation Oncology; Geinitz, H. [Technische Univ. Munich (Germany). Dept. of Radiation Oncology; Aschoff, R. [St.-Josef-Hospital, Gelsenkirchen-Horst (Germany). Dept. of Radiation Oncology; Bayerl, A. [Krems Hospital, Krems (Austria). Dept. of Radiation Oncology; Gerstein, J. [Frankfurt Univ. (Germany). Dept. of Radiation Oncology; Hipp, M.; Schaefer, C. [Regensburg Univ. (Germany). Dept. of Radiation Oncology; Oorschot, B. van [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Wypior, H.J. [Landshut Hospital, Landshut (Germany). Dept. of Radiation Oncology

    2013-01-15

    Purpose: Proxies of patients with poor performance status could give useful information about the patients' quality of life (QoL). We applied a newly developed questionnaire in a prospective QoL study of patients undergoing radiotherapy for brain metastases in order to make the first move to validate this instrument, and we compared the results with scores obtained using validated patient-completed instruments. Materials and methods: From January 2007 to June 2010, 166 patients with previously untreated brain metastases were recruited at 14 centers in Germany and Austria. The EORTC-QLQ-C15-PAL and the brain module BN20 were used to assess QoL in patients at the start of treatment and 3 months later. At the same time points, 141 of their proxies estimated the QoL with the new DEGRO brain module (DBM), a ten-item questionnaire rating the general condition as well as functions and impairment by symptoms in areas relevant to patients with brain metastases. Results: At 3 months, 85 of 141 patients (60%) with initial response by a proxy were alive. Sixty-seven of these patients (79% of 3-month survivors) and 65 proxies completed the second set of questionnaires. After 3 months, QoL significantly deteriorated in all items of proxy-assessed QoL except headache. Correlations between self-assessed and proxy-assessed QoL were high in single items such as nausea, headache, and fatigue. Conclusions: The high correlation between self-assessment and proxy ratings as well as a similar change over time for both approaches suggest that in patients with brain metastases, proxy assessment using the DBM questionnaire can be an alternative approach to obtaining QoL data when patients are unable to complete questionnaires themselves. Our self-constructed and first applied DBM is the only highly specific instrument for patients with brain metastases, but further tests are needed for its final validation. (orig.)

  2. The utility of SPECT lung perfusion cans in assessing the changes in pulmonary function after radiotherapy for patients with lung cancer

    International Nuclear Information System (INIS)

    Objective: To assess the pulmonary function by lung perfusion scintigraphy in lung cancer patients treated with thoracic conform.al radiotherapy. Materials: Between June and December 2003, 21 lung cancer patients treated with thoracic radiotherapy (RT) performed Single photon emission computed tomography (SPECT) lung perfusion scans before RT and after 40 Gy-50 Gy radiation. Seventeen of these patients receiving thoracic 3-dimension conformal radiotherapy were included in this study. Severn patients had small cell lung carcinoma, 8 squamous cell carcinoma, and 2 no classification. There are 15 male and 2 female. The median age was 56 years, with a range of 46-78 years. SPECT lung perfusion scans were obtained following the intravenous administration of 185 MBq (5 mCi) of technetium-99m-labeled macroaggregated albumin (MAA). Images of static (ANT, POST, RAO, RPO, LAO, LPO, RLAT, LLAT) and tomography (transverse, sagittal, coronal) were acquired after injection using a dual-head SPECT (GE MillenniumTM VGV, Hawkeye) with low energy high resolution collimator, All patients were in supine with their arms above their head. Every attempt was made to have all of the scans and the radiation treatment delivered with the patient in a similar position. At the same time X-ray or CT scan were performed. The pre-RT CT or X-ray of the thorax and SPECT images were visually reviewed to assess the presence of hypoperfusion. Each of post-RT SPECT scan was also visually compared with the pre-RT SPECT image to detect whether or not reperfusion of previously under perfused areas. Furthermore, each pre-RT and post-RT SPECT image set was visually registered with the pre-RT planning CT images; the 3-D dose distribution was thus registered with the lung perfusion scan. The radiotherapy field (>20 Gy) was drawn as a region of interest (ROI) in the SPECT transversal images. The proportion of radioactive count within this ROI relative to total lung count in one slice was determined. Student's t

  3. Positron Emission Tomography for Assessing Local Failure After Stereotactic Body Radiotherapy for Non-Small-Cell Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: We analyzed whether positron emission tomography (PET)/computed tomography standardized uptake values (SUVs) after stereotactic body radiotherapy (SBRT) could predict local recurrence (LR) in non-small-cell lung cancer (NSCLC). Methods and Materials: This study comprised 128 patients with Stage I (n = 68) or isolated recurrent/secondary parenchymal (n = 60) NSCLC treated with image-guided SBRT to 50 Gy over 4 consecutive days; prior radiotherapy was allowed. PET/computed tomography scans were obtained before therapy and at 1 to 6 months after therapy, as well as subsequently as clinically indicated. Continuous variables were analyzed with Kruskal-Wallis tests and categorical variables with Pearson chi-square or Fisher exact tests. Actuarial local failure rates were calculated with the Kaplan-Meier method. Results: At a median follow-up of 31 months (range, 6–71 months), the actuarial 1-, 2-, and 3-year local control rates were 100%, 98.5%, and 98.5%, respectively, in the Stage I group and 95.8%, 87.6%, and 85.8%, respectively, in the recurrent group. The cumulative rates of regional nodal recurrence and distant metastasis were 8.8% (6 of 68) and 14.7% (10 of 68), respectively, for the Stage I group and 11.7% (7 of 60) and 16.7% (10 of 60), respectively, for the recurrent group. Univariate analysis showed that SUVs obtained 12.1 to 24 months after treatment for the Stage I group (p = 0.007) and 6.1 to 12 months and 12.1 to 24 months after treatment for the recurrent group were associated with LR (p < 0.001 for both). Of the 128 patients, 17 (13.3%) had ipsilateral consolidation after SBRT but no elevated metabolic activity on PET; none had LR. The cutoff maximum SUV of 5 was found to have 100% sensitivity, 91% specificity, a 50% positive predictive value, and a 100% negative predictive value for predicting LR. Conclusions: PET was helpful for distinguishing SBRT-induced consolidation from LR. SUVs obtained more than 6 months after SBRT for NSCLC were

  4. Poster — Thur Eve — 66: Robustness Assessment of a Novel IMRT Planning Method for Lung Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Ahanj, M. [Department of Physics, Ryerson University, Toronto, ON (Canada); Bissonnette, J.-P. [Department of Radiation Physics, Princess Margaret Cancer Centre, Toronto, ON, Department of Radiation Oncology, University of Toronto, Toronto, ON (Canada); Heath, E. [Department of Physics, Carleton University, Ottawa, ON (Canada); McCann, C. [Odette Cancer Center, Sunnybrook Health Sciences Center, Toronto, ON (Canada)

    2014-08-15

    Conventional radiotherapy treatment planning for lung cancer accounts for tumour motion by increasing the beam apertures. We recently developed an IMRT planning strategy which uses reduced beam apertures in combination with an edge enhancing boost of 110% of the prescription dose to the volume that corresponds to the portion of the CTV that moves outside of the reduced beam. Previous results showed that this approach ensures target coverage while reducing lung dose. In the current study, we evaluate the robustness of this boost volume approach to changes in respiratory motion, including amplitude and phase weight variations. ITV and boost volume plans were generated for 5 NSCLC patients with respiratory motion amplitudes ranging from 1 to 2 cm. A standard 5mm PTV margin was used for all plans. The ORBIT treatment planning tool was used to plan and accumulate dose over 10 respiratory phases defined by the 4DCT datasets. For the phase weight variation study, dose was accumulated for three scenarios: equally-weighted-phases, higher weight assigned to exhale phases and higher weight assigned to inhale phases. For the amplitude variation study, a numerical phantom was used to generate 4DCT datasets corresponding to 7 mm, 10 mm and 14 mm motion amplitudes. Preliminary results found that delivered plans for all phase weight scenarios were clinically acceptable. When normalized to mean lung dose, the boost volume plan delivered 5% more dose to the CTV which indicates the potential for dose escalation using this approach.

  5. Poster — Thur Eve — 66: Robustness Assessment of a Novel IMRT Planning Method for Lung Radiotherapy

    International Nuclear Information System (INIS)

    Conventional radiotherapy treatment planning for lung cancer accounts for tumour motion by increasing the beam apertures. We recently developed an IMRT planning strategy which uses reduced beam apertures in combination with an edge enhancing boost of 110% of the prescription dose to the volume that corresponds to the portion of the CTV that moves outside of the reduced beam. Previous results showed that this approach ensures target coverage while reducing lung dose. In the current study, we evaluate the robustness of this boost volume approach to changes in respiratory motion, including amplitude and phase weight variations. ITV and boost volume plans were generated for 5 NSCLC patients with respiratory motion amplitudes ranging from 1 to 2 cm. A standard 5mm PTV margin was used for all plans. The ORBIT treatment planning tool was used to plan and accumulate dose over 10 respiratory phases defined by the 4DCT datasets. For the phase weight variation study, dose was accumulated for three scenarios: equally-weighted-phases, higher weight assigned to exhale phases and higher weight assigned to inhale phases. For the amplitude variation study, a numerical phantom was used to generate 4DCT datasets corresponding to 7 mm, 10 mm and 14 mm motion amplitudes. Preliminary results found that delivered plans for all phase weight scenarios were clinically acceptable. When normalized to mean lung dose, the boost volume plan delivered 5% more dose to the CTV which indicates the potential for dose escalation using this approach

  6. Analysis of risk assessment of brachytherapy from the radiotherapy services of the metropolitan region of Rio de Janeiro, RJ, Brazil

    International Nuclear Information System (INIS)

    Currently there are few applications on the risk analysis procedures related to radiotherapy, mainly in the practice of brachytherapy. The objective of this study was to analyze the perception of risk levels, present in the practice of high dose rate brachytherapy (HDR), using a form based on the concept of the risk matrix and a database (SEVRRA) containing information about the processes related to routine brachytherapy. A form containing information regarding the brachytherapy procedure HDR and an attachment indicating how to complete it properly was delivered to a medical physicist of each service/institution. The reference value for the risk levels found, considered acceptable for all performed analyzes, was set at a percentage limit of 33% (assuming a failure in each 3 existing processes). The results showed that the overall risk analysis showed a value for average percentage of prioritized risk of 18% below the recommended range. About the analyzed groups, the higher average percentage of relative risk was found less than 12% of the recommended range, associated with the group of patients. On existing steps, the highest average percentage of relative risk was found less than 1% of the recommended range, associated with stage records and treatment planning. This study showed that although this procedure does not have a large history of accidents, still poses risks considerable that must be managed with great accuracy and immediate action to an effective decrease these risk percentages

  7. Diffusion-weighted magnetic resonance imaging during radiotherapy of locally advanced cervical cancer - treatment response assessment using different segmentation methods

    DEFF Research Database (Denmark)

    Haack, Søren; Tanderup, Kari; Kallehauge, Jesper Folsted;

    2015-01-01

    BACKGROUND: Diffusion-weighted magnetic resonance imaging (DW-MRI) and the derived apparent diffusion coefficient (ADC) value has potential for monitoring tumor response to radiotherapy (RT). Method used for segmentation of volumes with reduced diffusion will influence both volume size and observed...... volumes changed significantly during treatment (p < 0.01). There was a significant difference in JSI among segmentation methods at time of PRERT (p < 0.016) with region growing having the lowest JSIGTV (mean± sd: 0.35 ± 0.1), followed by the SD4 method (mean± sd: 0.50 ± 0.1) and clustering (mean± sd: 0.......52 ± 0.3). There was no significant difference in mean ADC value compared at same treatment time. Mean tumor ADC value increased significantly (p < 0.01) for all methods across treatment time. CONCLUSION: Among the three semi-automatic segmentations of hyper-intense intensities on DW-MR images...

  8. The Value of Down Syndrome Screening Combined with Four Dimensional Colour Doppler Ultrasound in Prenatal Diagnosis%唐氏筛查联合四维彩超在产前诊断中的价值

    Institute of Scientific and Technical Information of China (English)

    邓玲; 汤辉; 黎兴盛; 郭平

    2015-01-01

    Objective:To explore the application value of Down syndrome screening combined with four dimensional colour doppler ultrasound in prenatal diagnosis.Method:From January 2011 to December 2014, 2578 cases of pregnant women for 14 to 24 weeks were selected in maternity clinics in our hospital,they were examined by Down syndrome screening and four dimensional colour doppler ultrasound.Result:2578 cases of pregnant women were all examined by Down syndrome screening and four dimensional colour doppler ultrasound. Positive rate of Down syndrome screening was 4.84%,positive rate of was four dimensional colour doppler ultrasound was 0.96%,positive rate of combined examination was 5.81%, positive rate between Down syndrome screening and combined examination had no statistical significance (P>0.05),positive rate between four dimensional colour doppler ultrasound and combined examination had statistical significance(P0.05),与四维彩超筛查比较差异有统计学意义(P<0.05).结论:唐氏筛查联合四维彩超在产前筛查中的意义重大,可提高唐氏儿和其他染色体病儿及各种畸形的诊断率,及时做出判断是否终止妊娠,为家庭和社会减轻了沉重的负担.

  9. Guide for the self-assessment of risks brought upon patients in external radiotherapy - ASN guide nr 4, Index 0, Release of the 15/01/2009

    International Nuclear Information System (INIS)

    This document contains a user's guide for radiotherapy centres which is to be read before completing the form of analysis of failure modes, their effects and criticality (AMDEC), this form which must be completed by each radiotherapy centre, and a report explaining the methodology which has been adopted to elaborate this guide

  10. Prospective Preference Assessment of Patients' Willingness to Participate in a Randomized Controlled Trial of Intensity-Modulated Radiotherapy Versus Proton Therapy for Localized Prostate Cancer

    International Nuclear Information System (INIS)

    Purpose: To investigate patients’ willingness to participate (WTP) in a randomized controlled trial (RCT) comparing intensity-modulated radiotherapy (IMRT) with proton beam therapy (PBT) for prostate cancer (PCa). Methods and Materials: We undertook a qualitative research study in which we prospectively enrolled patients with clinically localized PCa. We used purposive sampling to ensure a diverse sample based on age, race, travel distance, and physician. Patients participated in a semi-structured interview in which they reviewed a description of a hypothetical RCT, were asked open-ended and focused follow-up questions regarding their motivations for and concerns about enrollment, and completed a questionnaire assessing characteristics such as demographics and prior knowledge of IMRT or PBT. Patients’ stated WTP was assessed using a 6-point Likert scale. Results: Forty-six eligible patients (33 white, 13 black) were enrolled from the practices of eight physicians. We identified 21 factors that impacted patients’ WTP, which largely centered on five major themes: altruism/desire to compare treatments, randomization, deference to physician opinion, financial incentives, and time demands/scheduling. Most patients (27 of 46, 59%) stated they would either “definitely” or “probably” participate. Seventeen percent (8 of 46) stated they would “definitely not” or “probably not” enroll, most of whom (6 of 8) preferred PBT before their physician visit. Conclusions: A substantial proportion of patients indicated high WTP in a RCT comparing IMRT and PBT for PCa.

  11. The place radiotherapy alone with respect to surgery and radiotherapy in locally advanced vulva cancers

    International Nuclear Information System (INIS)

    The author report a study which aimed at evaluating the place or radiotherapy associated with surgery and of radiotherapy without surgery when taking into care locally advanced vulva cancers. The study is based on 46 cases. After 24 months, different aspects, such as recurrence and survival, have been assessed. It appears that there is no survival difference without recurrences between both sets. Short communication

  12. Dimensional Reduction of N=1, E_8 SYM over SU(3)/U(1) x U(1) x Z_3 and its four-dimensional effective action

    CERN Document Server

    Irges, Nikos; Zoupanos, George

    2011-01-01

    We present an extension of the Standard Model inspired by the E_8 x E_8 Heterotic String. In order that a reasonable effective Lagrangian is presented we neglect everything else other than the ten-dimensional N=1 supersymmetric Yang-Mills sector associated with one of the gauge factors and certain couplings necessary for anomaly cancellation. We consider a compactified space-time M_4 x B_0 / Z_3, where B_0 is the nearly-Kaehler manifold SU(3)/U(1) x U(1) and Z_3 is a freely acting discrete group on B_0. Then we reduce dimensionally the E_8 on this manifold and we employ the Wilson flux mechanism leading in four dimensions to an SU(3)^3 gauge theory with the spectrum of a N=1 supersymmetric theory. We compute the effective four-dimensional Lagrangian and demonstrate that an extension of the Standard Model is obtained with interesting features including a conserved baryon number and fixed tree level Yukawa couplings and scalar potential. The spectrum contains new states such as right handed neutrinos and heavy ...

  13. Investigation of dissipation in the tilting degree of freedom from four-dimensional Langevin dynamics of heavy-ion-induced fission

    International Nuclear Information System (INIS)

    A four-dimensional dynamical model based on Langevin equations was applied to calculate a wide set of experimental observables for heavy fissioning compound nuclei. Three collective shape coordinates plus the tilting coordinate were considered dynamically from the ground state deformation to the scission into fission fragments. A modified one-body mechanism for nuclear dissipation with a reduction coefficient ks of the contribution from a ‘wall’ formula was used for shapes parameters. Different possibilities of deformation-dependent dissipation coefficient for the tilting coordinate (γK) were investigated. Presented results demonstrate that the influence of the ks and γK parameters on the calculated quantities can be selectively probed. The nuclear viscosity with respect to the nuclear shape parameters influences the pre>, the fission fragment mass–energy distribution parameters, and the angular distribution of fission fragments. At the same time the viscosity coefficient γK affects the angular distribution of fission fragments only. The independence of anisotropy on the fission fragment mass is found at both Langevin calculations performed with deformation-dependent and constant γK coefficients. (paper)

  14. Real-Space Imaging of Carrier Dynamics of Materials Surfaces by Second-Generation Four-Dimensional Scanning Ultrafast Electron Microscopy

    KAUST Repository

    Sun, Jingya

    2015-09-14

    In the fields of photocatalysis and photovoltaics, ultrafast dynamical processes, including carrier trapping and recombination on material surfaces, are among the key factors that determine the overall energy conversion efficiency. A precise knowledge of these dynamical events on the nanometer (nm) and femtosecond (fs) scales was not accessible until recently. The only way to access such fundamental processes fully is to map the surface dynamics selectively in real space and time. In this study, we establish a second generation of four-dimensional scanning ultrafast electron microscopy (4D S-UEM) and demonstrate the ability to record time-resolved images (snapshots) of material surfaces with 650 fs and ∼5 nm temporal and spatial resolutions, respectively. In this method, the surface of a specimen is excited by a clocking optical pulse and imaged using a pulsed primary electron beam as a probe pulse, generating secondary electrons (SEs), which are emitted from the surface of the specimen in a manner that is sensitive to the local electron/hole density. This method provides direct and controllable information regarding surface dynamics. We clearly demonstrate how the surface morphology, grains, defects, and nanostructured features can significantly impact the overall dynamical processes on the surface of photoactive-materials. In addition, the ability to access two regimes of dynamical probing in a single experiment and the energy loss of SEs in semiconductor-nanoscale materials will also be discussed.

  15. Chemical and biogeophysical impact of four-dimensional (4D) seismic exploration in sub-Saharan Africa, and restoration of dysfunctionalized mangrove forests in the prospect areas.

    Science.gov (United States)

    Osuji, Leo C; Ayolagha, G; Obute, G C; Ohabuike, H C

    2007-09-01

    Four-dimensional (4D) seismic exploration, an improved geophysical technique for hydrocarbon-data acquisition, was applied for the first time in the Nembe Creek prospect area of Nigeria. The affected soils were slightly alkaline in situ when wet (pH 7.2), but extremely acidic when dry (pH 3.0). The organic carbon content (4.6-26.8%) and other physicochemical properties of soils and water (N, P, and heavy-metal contents, etc.) were higher than the baseline values obtained in 2001 before seismic profiling. Most values also exceeded the baseline compliance standards of the Department of Petroleum Resources (DPR), the World Health Organization (WHO), and the Federal Environmental Protection Agency (FEPA). Rehabilitation of the affected areas was achieved by stabilizing the mangrove floor by liming and appropriate application of nutrients, followed by replanting the cut seismic lines over a distance of 1,372 km with different mangrove species, including juvenile Rhizophora racemosa, R. mangle, and Avicennia species, which were transferred from nursery points. Quicker post-operational intervention is recommended for future 4D surveys, because the time lag between the end of seismic activity and post-impact investigation is critical in determining the relationship between activity and impact: the longer the intervening period, the more mooted the interaction. PMID:17886833

  16. Quality of life assessment in patients with Graves' disease and progressive infiltrative ophthalmopathy during combined treatment with methylprednisolone and orbital radiotherapy

    International Nuclear Information System (INIS)

    Introduction: The aim of the study was to assess quality of life (QoL) in patients with infiltrative form of Graves' ophthalmopathy (GO) during the combined pulse treatment with methylprednisolone and orbital radiotherapy, and also to search for the relation between the results of ophthalmopathy treatment and changes in QoL. Material and methods: The study involved 29 patients aged 25-74 (the mean age: 52 ±6 years) with infiltrative form of GO. They were classified for ophthalmopathy treatment on the basis of the following factors: the obtained euthyreosis, progressive character of eye changes, the level of eye changes determined on the basis of NO SPECS classification (at least class 3c), ophthalmopathy index (OI) according to Donaldson. 4. GO was diagnosed as active if CAS (clinical activity score) . 4. During the treatment, the patients received 6 cycles of methylprednisolone sodium succinate in doses of 1,0 g/24 h given as one-hour-long intravenous infusions for three successive days in a week. Between the 2nd and 4th cycle of Solu-Medrol, orbital radiotherapy with 10 MeV X-rays was performed. The control group was made up of healthy volunteers selected with regard to sex, age, educational background and nicotine addiction so as they corresponded with the study group. It involved 53 individuals aged 21-75 (the mean age: 52,4 ±14 years). QoL was assessed by means of the MOS SF-36 estionnaire. Results: Patients with GO evaluated their QoL lower than healthy individuals, which referred to physical functioning, physical and emotional role functioning, general health, vitality, social functioning, mental health and bodily pain. No correlation was found between quality of life and such factors as age, sex, or duration time of Graves disease and ophthalmopathy. Analogically, no relation was observed between the activity and stage of clinical development of eye changes and QoL. The use of the combined GO therapy contributed to a considerable decrease in the

  17. Imaging in radiotherapy

    International Nuclear Information System (INIS)

    The diagnostic methodologies used for the radiotherapy planning have undergone great developments in the last 30 years. Since the 1980s, after the introduction of the CT scanner, the modality for the planning moved beyond the planar 2D assessment to approach a real and more realistic volumetric 3D definition. Consequently the dose distribution, previously obtained by means of an overly simple approximation, became increasingly complex, better tailoring the true shape of the tumour. The final therapeutic improvement has been obtained by a parallel increase in the complexity of the irradiating units: the Linacs for therapy have, in fact, been equipped with a full accessory set capable to modulate the fluence (IMRT) and to check the correct target position continuously during the therapy session (IMRT-IGRT). The multimodal diagnostic approach, which integrates diagnostic information, from images of the patient taken with CT, NMR, PET and US, further improves the data for a biological and topological optimization of the radiotherapy plan and consequently of the dose distribution in the Planning Target Volume. Proteomic and genomic analysis will be the next step in tumour diagnosis. These methods will provide the planners with further information, for a true personalization of the treatment regimen and the assessment of the predictive essays for each tumour and each patient.

  18. Phase I Clinical Trial Assessing Temozolomide and Tamoxifen With Concomitant Radiotherapy for Treatment of High-Grade Glioma

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Shilpen, E-mail: Shilpenp@uw.edu [Department of Radiation Oncology, University of Washington, Seattle, WA (United States); DiBiase, Steven [Robert Wood Johnson School of Medicine, Camden, NJ (United States); Meisenberg, Barry [DeCesaris Cancer Institute, Annapolis, MD (United States); Flannery, Todd [Princeton Radiation Oncology, Princeton, NJ (United States); Patel, Ashish [Division of Radiation Oncology, Abington Memorial Hospital, Abington, PA (United States); Dhople, Anil [MIMA Cancer Center, Melbourne, FL (Australia); Cheston, Sally; Amin, Pradip [Department of Radiation Oncology, University of Maryland, Baltimore, MD (United States)

    2012-02-01

    Purpose: The new standard treatment of glioblastoma multiforme is concurrent radiotherapy (RT) and temozolomide. The proliferation of high-grade gliomas might be partly dependent on protein kinase C-mediated pathways. Tamoxifen has been shown in vitro to inhibit protein kinase C through estrogen receptor-independent antineoplastic effects. This Phase I trial was designed to determine the maximal tolerated dose (MTD) of tamoxifen when given with temozolomide and concurrent RT to patients with high-grade gliomas. Methods and Materials: A total of 17 consecutive patients in four cohorts with World Health Organization Grade 3 (n = 2) and 4 (n = 15) gliomas were given tamoxifen twice daily during 6 weeks of concurrent RT and temozolomide. Eligibility included histologic diagnosis, age >18 years old, Karnofsky performance status {>=}60, and no previous brain RT or chemotherapy. The starting dose was 50 mg/m{sup 2} divided twice daily. If no dose-limiting toxicities (DLTs) occurred in 3 patients, the dose was escalated in 25-mg/m{sup 2} increments until the MTD was reached. When {>=}2 patients within a cohort experienced a DLT, the MTD had been exceeded. Temozolomide was given with RT at 75 mg/m{sup 2}. A dose of 60 Gy in 2 Gy/d fractions to a partial brain field was delivered. Results: A total of 6 patients in Cohort 4 had received tamoxifen at 125 mg/m{sup 2}. One patient was excluded, and the fourth patient developed Grade 4 thrombocytopenia (DLT). Thus, 3 more patients needed to be enrolled. A deep venous thrombosis (DLT) occurred in the sixth patient. Thus, the MTD was 100 mg/m{sup 2}. Conclusions: The MTD of tamoxifen was 100 mg/m{sup 2} when given concurrently with temozolomide 75 mg/m{sup 2} and RT. Tamoxifen might have a role in the initial treatment of high-grade gliomas and should be studied in future Phase II trials building on the newly established platform of concurrent chemoradiotherapy.

  19. Mid-Ventilation Concept for Mobile Pulmonary Tumors: Internal Tumor Trajectory Versus Selective Reconstruction of Four-Dimensional Computed Tomography Frames Based on External Breathing Motion

    International Nuclear Information System (INIS)

    Purpose: To evaluate the accuracy of direct reconstruction of mid-ventilation and peak-phase four-dimensional (4D) computed tomography (CT) frames based on the external breathing signal. Methods and Materials: For 11 patients with 15 pulmonary targets, a respiration-correlated CT study (4D CT) was acquired for treatment planning. After retrospective time-based sorting of raw projection data and reconstruction of eight CT frames equally distributed over the breathing cycle, mean tumor position (Pmean), mid-ventilation frame, and breathing motion were evaluated based on the internal tumor trajectory. Analysis of the external breathing signal (pressure sensor around abdomen) with amplitude-based sorting of projections was performed for direct reconstruction of the mid-ventilation frame and frames at peak phases of the breathing cycle. Results: On the basis of the eight 4D CT frames equally spaced in time, tumor motion was largest in the craniocaudal direction, with 12 ± 7 mm on average. Tumor motion between the two frames reconstructed at peak phases was not different in the craniocaudal and anterior-posterior directions but was systematically smaller in the left-right direction by 1 mm on average. The 3-dimensional distance between Pmean and the tumor position in the mid-ventilation frame based on the internal tumor trajectory was 1.2 ± 1 mm. Reconstruction of the mid-ventilation frame at the mean amplitude position of the external breathing signal resulted in tumor positions 2.0 ± 1.1 mm distant from Pmean. Breathing-induced motion artifacts in mid-ventilation frames caused negligible changes in tumor volume and shape. Conclusions: Direct reconstruction of the mid-ventilation frame and frames at peak phases based on the external breathing signal was reliable. This makes the reconstruction of only three 4D CT frames sufficient for application of the mid-ventilation technique in clinical practice.

  20. Correlations of third-trimester hiatal biometry obtained using four-dimensional translabial ultrasonography with the delivery route in nulliparous pregnant women

    Directory of Open Access Journals (Sweden)

    Teerayut Temtanakitpaisan

    2016-01-01

    Full Text Available Purpose: The goal of this study was to evaluate normal hiatal dimensions in the third trimester in nulliparous Thai pregnant women and to establish which biometric factors were associated with various pregnancy outcomes. Methods: Fifty-seven consecutive nulliparous pregnant Thai women in their third trimester were recruited on a voluntary basis from April to October 2014. All subjects underwent four-dimensional (4D translabial ultrasonography. Hiatal biometric parameters were measured at rest, while performing a Valsalva maneuver, and during contraction. Information about the patients’ eventual deliveries was obtained from their medical records. Results: The mean values of the patients’ age, body mass index, and gestational age at the time of examination were 27.4±5.47 years, 26.7±3.48 kg/m2, and 36.6±1.49 weeks, respectively. No subjects had vaginal lumps or experienced prolapse greater than stage 1 of the Pelvic Organ Prolapse Quantification system. Ultrasonography showed that the mean values of the hiatal area at rest, while performing a Valsalva maneuver, and during contraction were 13.10±2.92 cm2, 17.50±4.81 cm2, and 9.69±2.09 cm2, respectively. The hiatal area at rest, the axial measurement at rest, and the axial measurement while performing a Valsalva maneuver were significantly associated with the route of delivery (P=0.02, P=0.04, and P=0.03, respectively. Conclusion: The route of delivery was associated with hiatal biometric values measured using 4D translabial ultrasonography, based on the results of nulliparous Thai women in the third trimester.

  1. SU-D-18A-01: Tumor Motion Tracking with a Regional Deformable Registration Model for Four Dimensional Radiation Treatment of Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Chao, M; Lo, Y; Yuan, Y; Sheu, R; Rosenzweig, K [The Mount Sinai Medical Center, NY, NY (United States)

    2014-06-01

    Purpose: To develop a tumor motion model from four-dimensional computed tomography (4DCT) of thoracic patients and demonstrate its impact on 4D radiation therapy simulation. Methods: A regional deformable image registration algorithm was introduced to extract tumor motion out of patient's breathing cycle. The gross target volume (GTV) was manually delineated on a selected phase of 4DCT and a subregion with 10mm margin supplemented to the GTV was created on the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA). Together with 4DCT the structures were exported into an inhouse research platform. A free form B-Spline deformable registration was carried out to map the subregion to other respiratory phases. The displacement vector fields were employed to propagate GTV contours with which the center of mass (CoM) of the GTV was computed for each breathing phase of 4DCT. The resultant GTV motion and its volumetric shape are utilized to facilitate 4D treatment planning. Five lung cancer patients undergoing stereotactic body radiation therapy were enrolled and their 4DCT sets were included in the study. Results: Application of the algorithm to five thoracic patients indicates that clinically satisfactory outcomes were achievable with a spatial accuracy better than 2mm for GTV contour propagation between adjacent phases, and 3mm between opposite phases. The GTV CoM was found to be in the range of 2.0mm through 2.5cm, depending upon the tumor location. Compared to the traditional whole image based registration, the computation of the regional model was found to be an order of magnitude more efficient. Conclusion: A regional deformable registration model was implemented to extract tumor motion. It will have widespread application in 4D radiation treatment planning in the future to maximally utilize the available spatial-tempo information.

  2. SU-D-18A-01: Tumor Motion Tracking with a Regional Deformable Registration Model for Four Dimensional Radiation Treatment of Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: To develop a tumor motion model from four-dimensional computed tomography (4DCT) of thoracic patients and demonstrate its impact on 4D radiation therapy simulation. Methods: A regional deformable image registration algorithm was introduced to extract tumor motion out of patient's breathing cycle. The gross target volume (GTV) was manually delineated on a selected phase of 4DCT and a subregion with 10mm margin supplemented to the GTV was created on the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA). Together with 4DCT the structures were exported into an inhouse research platform. A free form B-Spline deformable registration was carried out to map the subregion to other respiratory phases. The displacement vector fields were employed to propagate GTV contours with which the center of mass (CoM) of the GTV was computed for each breathing phase of 4DCT. The resultant GTV motion and its volumetric shape are utilized to facilitate 4D treatment planning. Five lung cancer patients undergoing stereotactic body radiation therapy were enrolled and their 4DCT sets were included in the study. Results: Application of the algorithm to five thoracic patients indicates that clinically satisfactory outcomes were achievable with a spatial accuracy better than 2mm for GTV contour propagation between adjacent phases, and 3mm between opposite phases. The GTV CoM was found to be in the range of 2.0mm through 2.5cm, depending upon the tumor location. Compared to the traditional whole image based registration, the computation of the regional model was found to be an order of magnitude more efficient. Conclusion: A regional deformable registration model was implemented to extract tumor motion. It will have widespread application in 4D radiation treatment planning in the future to maximally utilize the available spatial-tempo information

  3. Four-dimensional 13C/13C-edited nuclear Overhauser Enhancement Spectroscopy of a protein in solution: Application to interleukin 1β

    International Nuclear Information System (INIS)

    A four-dimensional 13C/13C-edited NOESY experiment is described which dramatically improves the resolution of protein NMR spectra and enables the straightforward assignment of nuclear Overhauser effects involving aliphatic and/or aromatic protons in larger proteins. The experiment is demonstrated for uniformly (>95%) 13C-labeled interleukin 1β, a protein of 153 residues and 17.4 kDa, which plays a key role in the immune response. NOEs between aliphatic and/or aromatic protons are first spread out into a third dimension by the 13C chemical shift of the carbon atom attached to the originating proton and subsequently into a fourth dimension by the 13C chemical shift of the carbon atom attached to the destination proton. Thus, each NOE cross peak is labeled by four chemical shifts. By this means, ambiguities in the assignment of NOEs that arise from chemical shift overlap and degeneracy are completely removed. Further, NOEs between protons with the same chemical shifts can readily be detected providing their attached carbon atoms have different 13C chemical shifts. The design of the pulse sequence requires special care to minimize the level of artifacts arising from undesired coherence transfer pathways, and in particular those associated with diagonal peaks which correspond to magnetization that has not been transferred from one proton to another. The 4D 13C/13C-edited NOESY experiment is characterized by high sensitivity as the through-bond transfer steps involve the large 1JCH (130 Hz) couplings, and it is possible to obtain high-quality spectra on 1-2 mM samples of 13C-labeled protein in as little as 3 days. This experiment should open up the application of protein structure determination by NMR to a large number of medium-sized proteins (150-300 residues) of biological interest

  4. Comparison of primary target volumes delineated on four-dimensional CT and 18 F-FDG PET/CT of non-small-cell lung cancer

    International Nuclear Information System (INIS)

    To determine the optimal threshold of 18 F-fluorodexyglucose (18 F-FDG) positron emission tomography CT (PET/CT) images that generates the best volumetric match to internal gross target volume (IGTV) based on four-dimensional CT (4DCT) images. Twenty patients with non-small cell lung cancer (NSCLC) underwent enhanced three-dimensional CT (3DCT) scan followed by enhanced 4DCT scan of the thorax under normal free breathing with the administration of intravenous contrast agents. A total of 100 ml of ioversol was injected intravenously, 2 ml/s for 3DCT and 1 ml/s for 4DCT. Then 18 F-FDG PET/CT scan was performed based on the same positioning parameters (the same immobilization devices and identical position verified by laser localizer as well as skin marks). Gross target volumes (GTVs) of the primary tumor were contoured on the ten phases images of 4DCT to generate IGTV10. GTVPET were determined with eight different threshold using an auto-contouring function. The differences in the position, volume, concordance index (CI) and degree of inclusion (DI) of the targets between GTVPET and IGTV10 were compared. The images from seventeen patients were suitable for further analysis. Significant differences between the centric coordinate positions of GTVPET (excluding GTVPET15%) and IGTV10 were observed only in z axes (P < 0.05). GTVPET15%, GTVPET25% and GTVPET2.0 were not statistically different from IGTV10 (P < 0.05). GTVPET15% approximated closely to IGTV10 with median percentage volume changes of 4.86%. The best CI was between IGTV10 and GTVPET15% (0.57). The best DI of IGTV10 in GTVPET was IGTV10 in GTVPET15% (0.80). None of the PET-based contours had both close spatial and volumetric approximation to the 4DCT IGTV10. At present 3D-PET/CT should not be used for IGTV generation

  5. Family physicians' perspectives regarding palliative radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To assess family physicians' views on common indications for palliative radiotherapy and to determine whether this influences patient referral. Methods and materials: A 30-item questionnaire evaluating radiotherapy knowledge and training developed at the Ottawa Regional Cancer Centre (ORCC) was mailed to a random sample of 400 family physicians in eastern Ontario, Canada. The completed surveys were collected and analyzed, and form the basis of this study. Results: A total of 172 completed surveys were received for a net response rate of 50% among practicing family physicians. Almost all of the physicians (97%) had recently seen cancer patients in their offices, with 85% regularly caring for patient with advanced cancer. Fifty-four percent had referred patients in the past for radiotherapy and 53% had contacted a radiation oncologist for advice. Physicians who were more knowledgeable about the common indications for palliative radiotherapy were significantly more likely to refer patients for radiotherapy (P<0.01). Inability to contact a radiation oncologist was correlated with not having referred patients for radiotherapy (P<0.01). Only 10% of the physicians had received radiotherapy education during their formal medical training. Conclusions: Many of the family physicians surveyed were unaware of the effectiveness of radiotherapy in a variety of common palliative situations, and radiotherapy referral was correlated with knowledge about the indications for palliative radiotherapy. This was not surprising given the limited education they received in this area and the limited contact they have had with radiation oncologists. Strategies need to be developed to improve continuing medical education opportunities for family physicians and to facilitate more interaction between these physicians and radiation oncologists

  6. Prospective Preference Assessment of Patients' Willingness to Participate in a Randomized Controlled Trial of Intensity-Modulated Radiotherapy Versus Proton Therapy for Localized Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Anand [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States); Efstathiou, Jason A.; Paly, Jonathan J. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Halpern, Scott D. [Department of Medicine, University of Pennsylvania, Philadelphia, PA (United States); Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, PA (United States); Center for Bioethics, University of Pennsylvania, Philadelphia, PA (United States); Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, PA (United States); Bruner, Deborah W. [Winship Cancer Institute, Emory University, Atlanta, GA (United States); Christodouleas, John P. [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States); Coen, John J. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Deville, Curtiland; Vapiwala, Neha [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States); Shipley, William U.; Zietman, Anthony L. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Hahn, Stephen M. [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States); Bekelman, Justin E., E-mail: bekelman@uphs.upenn.edu [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States); Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, PA (United States)

    2012-05-01

    Purpose: To investigate patients' willingness to participate (WTP) in a randomized controlled trial (RCT) comparing intensity-modulated radiotherapy (IMRT) with proton beam therapy (PBT) for prostate cancer (PCa). Methods and Materials: We undertook a qualitative research study in which we prospectively enrolled patients with clinically localized PCa. We used purposive sampling to ensure a diverse sample based on age, race, travel distance, and physician. Patients participated in a semi-structured interview in which they reviewed a description of a hypothetical RCT, were asked open-ended and focused follow-up questions regarding their motivations for and concerns about enrollment, and completed a questionnaire assessing characteristics such as demographics and prior knowledge of IMRT or PBT. Patients' stated WTP was assessed using a 6-point Likert scale. Results: Forty-six eligible patients (33 white, 13 black) were enrolled from the practices of eight physicians. We identified 21 factors that impacted patients' WTP, which largely centered on five major themes: altruism/desire to compare treatments, randomization, deference to physician opinion, financial incentives, and time demands/scheduling. Most patients (27 of 46, 59%) stated they would either 'definitely' or 'probably' participate. Seventeen percent (8 of 46) stated they would 'definitely not' or 'probably not' enroll, most of whom (6 of 8) preferred PBT before their physician visit. Conclusions: A substantial proportion of patients indicated high WTP in a RCT comparing IMRT and PBT for PCa.

  7. Evaluation of novel radiotherapy technologies: what evidence is needed to assess their clinical and cost effectiveness, and how should we get it?

    Science.gov (United States)

    van Loon, Judith; Grutters, Janneke; Macbeth, Fergus

    2012-04-01

    Technical innovations in radiation oncology--eg, intensity-modulated radiotherapy, stereotactic radiotherapy, and particle therapy--can be developed rapidly and introduced into the clinic even when costs associated with their use are much higher than those for conventional radiotherapy. Although clinical benefit is expected on the basis of superior biological and physical characteristics, data for clinical effectiveness of new radiotherapy techniques are scarce. Evidence from randomised clinical trials would be ideal but such studies focus mostly on new drugs. High investment costs and modifications over time make evaluation of novel radiotherapy technologies in clinical trials more complex. Here, we propose an algorithm for evaluation of the clinical and cost effectiveness of novel radiotherapy technologies. We suggest situations when randomised trials might be feasible and the type of trial that should be undertaken when they are not. Furthermore, we discuss the usefulness of dose-distribution models for estimation of expected clinical benefit and for selection of the patients' population with the highest expected benefit. Economic modelling, including the approach of real options analysis, can inform whether implementation of a technology should begin (based on available evidence) or be delayed (until further data are available), and it can indicate the best trial design and required sample size. PMID:22469127

  8. Self-assessed health-related quality of life (HRQOL) in men who completed radiotherapy for prostate cancer: Instrument validation and its relation to patient-assessed importance of symptoms

    International Nuclear Information System (INIS)

    Purpose: The focus of this study is on the development of a questionnaire designed to assess the disease-specific dimensions of health related quality of life (HRQOL) in the urinary function (UF), bowel function (BF), and sexual function (SF) domains in prostate cancer (PC) patients treated with radiation therapy. The scales created were tested for reliability and validity. In addition, we assessed the relationship between these dimensions and the degree to which a decreased HRQOL increases the degrees to which patients feel bothered about their symptoms. A similar study was conducted for patients during radiotherapy for PC, and similar validation was performed. Materials and Methods: Patients were given a six-page questionnaire during their follow-up visits after completing radiotherapy for PC. Questionnaire design is based on clinical experience and a literature review for assessment of three HRQOL dimensions. Likert-type questions were employed related to BF (12 items), UR (11 items), and SF (9 items), as well as a single question for each asking how bothersome the reported symptoms are to the patient. Items in each section were analyzed with principal components factor analysis for identifying factors from which were formed scales. Items found to have high factor loadings were grouped together to form 6 scales, two for each dimension, and the reliability and validity of the created scales were assessed. The scale scores were used for assessment whether increased symptoms resulted in increases in the perceived importance of the symptoms to patients. Results: For 93 cases, 2 scales were identified within each dimension from the factor analysis. For BF, the 2 scales were an Urgency scale (4 items) and a Daily Living scale (3 items). For UF, the 2 scales were an Urgency scale (5 items) and a Weakness of (Urinary) Stream scale (3 items). For SF, the 2 scales were an Interest/Satisfaction scale (5 items) and an Impotence scale (3 items). Internal

  9. Radiotherapy for Hodgkin lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Specht, Lena [Rigshospitalet Copenhagen Univ. (Denmark). Depts. of Oncology and Haematology; Yahalom, Joachim (eds.) [Memorial Sloan-Kettering Cancer, New York, NY (United States). Dept. of Radiation Oncology

    2011-07-01

    This book deals in detail with all aspects of the best practice in modern radiotherapy for Hodgkin lymphoma. It provides the background and rationale for the inclusion of radiotherapy in today's combined-modality approach, including special clinical situations such as Hodgkin lymphoma in children, in the pregnant patient, and in the elderly. Radiotherapy planning using state-of-the-art imaging, target definition, planning software, and treatment equipment is expounded in detail. Acute and long-term side effects of radiotherapy are analyzed, and the implications for modern radiotherapy approaches in Hodgkin lymphomas are explained. (orig.)

  10. Radiotherapy for Hodgkin lymphoma

    International Nuclear Information System (INIS)

    This book deals in detail with all aspects of the best practice in modern radiotherapy for Hodgkin lymphoma. It provides the background and rationale for the inclusion of radiotherapy in today's combined-modality approach, including special clinical situations such as Hodgkin lymphoma in children, in the pregnant patient, and in the elderly. Radiotherapy planning using state-of-the-art imaging, target definition, planning software, and treatment equipment is expounded in detail. Acute and long-term side effects of radiotherapy are analyzed, and the implications for modern radiotherapy approaches in Hodgkin lymphomas are explained. (orig.)

  11. The “universal property” of horizon entropy sum of black holes in four dimensional asymptotical (anti-)de-Sitter spacetime background

    International Nuclear Information System (INIS)

    We present a new “universal property” of entropy, that is the “entropy sum” relation of black holes in four dimensional (anti-)de-Sitter asymptotical background. They depend only on the cosmological constant with the necessary effect of the un-physical “virtual” horizon included in the spacetime where only the cosmological constant, mass of black hole, rotation parameter and Maxwell field exist. When there is more extra matter field in the spacetime, one will find the “entropy sum” is also dependent of the strength of these extra matter field. For both cases, we conclude that the “entropy sum” does not depend on the conserved charges M, Q and J, while it does depend on the property of background spacetime. We will mainly test the “entropy sum” relation in static, stationary black hole and some black hole with extra matter source (scalar hair and higher curvature) in the asymptotical (anti-)de-sitter spacetime background. Besides, we point out a newly found counter example of the mass independence of the ”entropy product” relation in the spacetime with extra scalar hair case, while the “entropy sum” relation still holds. These result are indeed suggestive to some underlying microscopic mechanism. Moreover, the cosmological constant and extra matter field dependence of the “entropy sum” of all horizon seems to reveal that “entropy sum” is more general as it is only related to the background field. For the case of asymptotical flat spacetime without any matter source, we give a note for the Kerr black hole case in appendix. One will find only mass dependence of “entropy sum” appears. It makes us believe that, considering the dependence of “entropy sum”, the mass background field may be regarded as the next order of cosmological constant background field and extra matter field. However, fully explaining the relationship between the “entropy sum” relation and background properties still requires further exploration

  12. Transrectal ultrasonically-guided core biopsies in the assessment of local cure of prostatic cancer after radical external beam radiotherapy

    International Nuclear Information System (INIS)

    Fifty-five patients were included in an extended follow-up after radical radiation therapy (RRT) for localized prostatic cancer (T1-3, Nx, M0). Local cure was assessed by a combination of digital rectal examination (DRE), transrectal ultrasound (TRUS) and systematic 'mapping' with TRUS-guided core biopsies (TGCB). After a mean follow-up of 6.8 years, 33% (18/55) of the patients were locally free of tumour, while in 67% (37/55) of cases residual cancer was demonstrated in the biopsies. Endocrine treatment did not influence the local cure rate, nor did the T stage of tumour grade at diagnosis of the cumulative radiation effect (CRE) values within the range of the present study. The sensitivity of DRE and TRUS was low; 37% and 20% respectively, while the specificity of the DRE and TRUS methods was 83% and 94% respectively. The conclusion of the study is that residual tomour was found in the high proportion of biopsied patients nearly 7 years after RRT and that multiple, TRUS-guided core biopsies are mandatory in the assessment of local cure in patients irradiated for prostatic cancer; both DRE and TRUS on their own are less reliable. (orig.)

  13. Radiotherapy for symptomatic vertebral hemangioma

    International Nuclear Information System (INIS)

    Purpose: Assessment of treatment results of symptomatic vertebral hemangiomas and review of the literature. Patients and Methods: Ten patients treated between 1974 to 1997 were retrospectively analyzed. Efficacy of treatment was determined according to improvement of pain and/or neurological symptoms. Results: Improvement was achieved in 8 of 10 patients. The initially existing neurological symptoms of 3 patients disappeared completely in 2 cases and improved in 1 case. Acute side effects were slight. Late side effects were not seen. A dose-effect relationship could not be assessed. There was no relapse. Conclusion: Radiotherapy with 30 Gy for symptomatic vertebral angioma as primary therapy is indicated. In case of neurological symptoms a radiotherapy after operative therapy is recommendable even if the patient is free of symptoms to prevent progress or relapse. (orig.)

  14. Self-assessed bowel toxicity after external beam radiotherapy for prostate cancer - predictive factors on irritative symptoms, incontinence and rectal bleeding

    International Nuclear Information System (INIS)

    The aim of the study was to evaluate self-assessed bowel toxicity after radiotherapy (RT) for prostate cancer. In contrast to rectal bleeding, information concerning irritative symptoms (rectal urgency, pain) and incontinence after RT has not been adequately documented and reported in the past. Patients (n = 286) have been surveyed prospectively before (A), at the last day (70.2-72.0 Gy; B), a median time of two (C) and 16 months after RT (D) using a validated questionnaire (Expanded Prostate Cancer Index Composite). Bowel domain score changes were analyzed and patient-/dose-volume-related factors tested for a predictive value on three separate factors (subscales): irritative symptoms, incontinence and rectal bleeding. Irritative symptoms were most strongly affected in the acute phase, but the scores of all subscales remained slightly lower at time D in comparison to baseline scores. Good correlations (correlation indices >0.4; p < 0.001 for all) were found between irritative and incontinence function/bother scores at times B-D, suggesting the presence of an urge incontinence for the majority of patients who reported uncontrolled leakage of stool. Planning target volume (PTV), haemorrhoids and stroke in past history were found to be independent predictive factors for rectal bleeding at time D. Chronic renal failure predisposed for lower irritative scores at time D. Paradoxically, patients with greater rectum volumes inside higher isodose levels presented with higher quality of life scores in the irritative and incontinence subscales. PTV and specific comorbidities are important predictive factors on adverse bowel quality of life changes after RT for prostate cancer. However, greater rectum volumes inside high isodose levels have not been found to be associated with lower quality of life scores

  15. TU-C-17A-04: BEST IN PHYSICS (THERAPY) - A Supervised Framework for Automatic Contour Assessment for Radiotherapy Planning of Head- Neck Cancer

    International Nuclear Information System (INIS)

    Purpose: Precise contour delineation of tumor targets and critical structures from CT simulations is essential for accurate radiotherapy (RT) treatment planning. However, manual and automatic delineation processes can be error prone due to limitations in imaging techniques and individual anatomic variability. Tedious and laborious manual verification is hence needed. This study develops a general framework for automatically assessing RT contours for head-neck cancer patients using geometric attribute distribution models (GADMs). Methods: Geometric attributes (centroid and volume) were computed from physician-approved RT contours of 29 head-neck patients. Considering anatomical correlation between neighboring structures, the GADM for each attribute was trained to characterize intra- and interpatient structure variations using principal component analysis. Each trained GADM was scalable and deformable, but constrained by the principal attribute variations of the training contours. A new hierarchical model adaptation algorithm was utilized to assess the RT contour correctness for a given patient. Receiver operating characteristic (ROC) curves were employed to evaluate and tune system parameters for the training models. Results: Experiments utilizing training and non-training data sets with simulated contouring errors were conducted to validate the framework performance. Promising assessment results of contour normality/abnormality for the training contour-based data were achieved with excellent accuracy (0.99), precision (0.99), recall (0.83), and F-score (0.97), while corresponding values of 0.84, 0.96, 0.83, and 0.9 were achieved for the non-training data. Furthermore, the areas under the ROC curves were above 0.9, validating the accuracy of this test. Conclusion: The proposed framework can reliably identify contour normality/abnormality based upon intra- and inter-structure constraints derived from clinically-approved contours. It also allows physicians to

  16. Main of probabilistic safety assessment (PSA) of the radiotherapy treatment process with a linear accelerator for medical purposes (linac)

    International Nuclear Information System (INIS)

    The radiation safety assessments traditionally have been based on analyzing the lessons you learn of new events that are becoming known. Although these methods are very valuable, their main limitation is that only cover known events and leave without consider other possible failures that have occurred or have not been published, This does not mean they can not occur. Other tools to analyze prospectively the safety, among which found Probabilistic Safety Assessment (PSA). This paper summarizes the project of American Forum of agencies radiological and nuclear regulators aimed at applying the methods of APS treatment process with a linear accelerator. We defined as unintended consequences accidental exposures both single patient and multiple patients. FMEA methodology was used to define events initiators of accidents and methods of event trees and trees failure to identify the accident sequences that may occur. A Once quantified the frequency of occurrence of accidental sequences Analyses of importance in determining the most recent events significant from the point of view of safety. We identified 158 of equipment failure modes and 295 errors human if they occurred would have the potential to cause the accidental exposures defined. We studied 118 of initiating events accident and 120 barriers. We studied 434 accident sequences. The accidental exposure of a single patient were 40 times likely that multiple patients. 100% of the total frequency of accidental exposures on a single patient is caused by human errors . 8% of the total frequency of accidental exposures on multiple patients initiating events may occur by equipment failure (Computerized tomography, treatment planning system, throttle linear) and 92% by human error. As part of the and recommendations of the study presents the events that are more contribution on the reduction of risk of accidental exposure. (author)

  17. Hormone levels in radiotherapy treatment related fatigue

    International Nuclear Information System (INIS)

    Radiotherapy is known to cause debilitating treatment related fatigue. Fatigue in general is a conglomeration of psychological, physical, hematological and unknown factors influencing the internal milieu of the cancer patient. Radiotherapy can add stress at the cellular and somatic level to aggravate further fatigue in cancer patients undergoing radiotherapy. Stress related hormones might be mediating in the development of fatigue. This is an ongoing prospective study to evaluate if the hormonal profile related to stress is influenced by radiotherapy treatment related fatigue. The study was conducted from September 2002 onwards in the division of Radiotherapy and Oncology of our Medical School. Previously untreated patients with histopathology proof of malignancy requiring external beam radiotherapy were considered for this study. Selection criteria were applied to exclude other causes of fatigue. Initial fatigue score was obtained using Pipers Fatigue Score questionnaire containing 23 questions, subsequently final fatigue score was obtained at the end of radiotherapy. Blood samples were obtained to estimate the levels of ACTH, TSH, HGH, and cortisol on the final assessment. The hormone levels were compared with resultant post radiotherapy fatigue score. At the time of reporting 50 patients were evaluable for the study. The total significant fatigue score was observed among 12 (24%) patients. The individual debilitating fatigue score were behavioral severity 14 (28%), affective meaning 14(28%), Sensory 13 (26%) and cognitive mood 10 (20%) respectively. From the analysis of hormonal profile, growth hormone level > 1 ng/mL and TSH <0.03 appears to be associated with high fatigue score (though statistically not significant); whereas there was no correlation with ACTH and serum cortisol level. In our prospective study severe radiotherapy treatment related fatigue was found among our patient population. Low levels of TSH and high levels of GH appear to be associated

  18. Unintended exposure in radiotherapy: Identification of prominent causes

    International Nuclear Information System (INIS)

    Background and purpose: Unintended exposures in radiotherapy are likely to occur when certain conditions that favour such exposures exist. Based on the frequency of occurrence of various causes of 100 events of unintended exposures in radiotherapy as derived from the analysis of published reports, a checklist for assessing the vulnerability of radiotherapy facilities for potential accidents has been prepared. The list presents items to be considered for safety critical assessments of a radiotherapy department for the improvement of patient safety and the entire radiotherapy processes. Materials and methods: The resources used for this paper consist of 100 unintended radiotherapy exposures and were derived from existing published reports. The analysis was performed by forming two templates: one consisting of 10 initiating events and another of 35 contributing factors. Results: Four most prominent initiating events were identified and together accounted for about 70% of all the unintended exposure events. Ten most prominent contributing factors were also identified and together accounted for about 70% of all the radiotherapy unintended exposure events covered under this study. Conclusion: With this knowledge of high frequency of occurrences, the identified four prominent initiating events and the 10 most prominent contributing factors must be checked and dealt with as a matter of priority when assessing the safety of a radiotherapy facility. A simple checklist for checking the quality assurance programmes of a radiotherapy department for every aspect of the design and delivery of radiation have been provided.

  19. Assessment of Monte Carlo algorithm for compliance with RTOG 0915 dosimetric criteria in peripheral lung cancer patients treated with stereotactic body radiotherapy.

    Science.gov (United States)

    Pokhrel, Damodar; Sood, Sumit; Badkul, Rajeev; Jiang, Hongyu; McClinton, Christopher; Lominska, Christopher; Kumar, Parvesh; Wang, Fen

    2016-01-01

    The purpose of the study was to evaluate Monte Carlo-generated dose distributions with the X-ray Voxel Monte Carlo (XVMC) algorithm in the treatment of peripheral lung cancer patients using stereotactic body radiotherapy (SBRT) with non-protocol dose-volume normalization and to assess plan outcomes utilizing RTOG 0915 dosimetric compliance criteria. The Radiation Therapy Oncology Group (RTOG) protocols for non-small cell lung cancer (NSCLC) currently require radiation dose to be calculated using tissue density heterogeneity corrections. Dosimetric criteria of RTOG 0915 were established based on superposition/convolution or heterogeneities corrected pencil beam (PB-hete) algorithms for dose calculations. Clinically, more accurate Monte Carlo (MC)-based algorithms are now routinely used for lung stereotactic body radiotherapy (SBRT) dose calculations. Hence, it is important to determine whether MC calculations in the delivery of lung SBRT can achieve RTOG standards. In this report, we evaluate iPlan generated MC plans for peripheral lung cancer patients treated with SBRT using dose-volume histogram (DVH) normalization to determine if the RTOG 0915 compliance criteria can be met. This study evaluated 20 Stage I-II NSCLC patients with peripherally located lung tumors, who underwent MC-based SBRT with heterogeneity correction using X-ray Voxel Monte Carlo (XVMC) algorithm (Brainlab iPlan version 4.1.2). Total dose of 50 to 54 Gy in 3 to 5 fractions was delivered to the planning target vol-ume (PTV) with at least 95% of the PTV receiving 100% of the prescription dose (V100% ≥ 95%). The internal target volume (ITV) was delineated on maximum intensity projection (MIP) images of 4D CT scans. The PTV included the ITV plus 5 mm uniform margin applied to the ITV. The PTV ranged from 11.1 to 163.0 cc (mean = 46.1 ± 38.7 cc). Organs at risk (OARs) including ribs were delineated on mean intensity projection (MeanIP) images of 4D CT scans. Optimal clinical MC SBRT plans were

  20. A correlation study on target displacement and volume variation of primary middle and distal esophageal cancer during normal respiration using four-dimensional CT

    International Nuclear Information System (INIS)

    Objective: To investigate the correlation between the motion of gross tumor volume (GTV) and the interested organs, and the correlation between the volume of GTV and the volume of heart and lung for the mid - and distal esophageal cancer using four - dimensional CT (4 DCT). Methods: Seventeen patients with middle/distal esophageal carcinoma underwent respiration-synchronized 4DCT simulation during free breathing. All image sets were registered with the reference image (T0 phase), and the GTV, the dome of diaphragm, lung and heart were delineated on CT images of the ten respiratory phases. The position of GTV, lung, heart and the dome of diaphragm were identified in all 4DCT phases,and the volume of GTV, lung and heart were also achieved. Paired sample t test were performed to compare the primary esophageal cancer displacement in the three directions. The pearson correlation test was use to study the correlation of GTV motion with the OARs , and the volume correlation of GTV with lung and heart.Results The maximum displacement of the GTV were 0.19 cm, 0.17 cm, and 0.48 cm, respectively in x, y and z directions. And the displacement were significant different between z and x, y directions (t = - 3. 59, - 4. 09, P = 0.002, 0.001). The displacement of GTV correlated well with right lung and heart in three dimensions (TRL-x = 0.922, PRL-x = 0.000, TRL-y = 0.700, PRL-y = 0.024, rRL-z = 0.994, PrRL-z = 0.000; TH-x = 0.720, PH-x = 0.010, rH-y = 0.920, PH-y = 0.000, rH-z = 0.910, PH-z = 0.000), and only significantly associated with left lung in z direction (r = 0.987, P = 0.000). There was a good correlation between GTV and the dome of diaphragm in z direction (rL = 0.918, PL = 0.000; rR= 0.928, PR= 0.000). Changes in the GTV volume was correlated well with the lung volume (rLL = - 0.680, PLL =0.031; rrL = - 0.670, PrL = 0.034), but the correlation was not significant with the heart (r= -0.368, P= 0.295) during respiratory cycle. Conclusions: For middle/distal esophageal

  1. Dosimetric impact of geometric errors due to respiratory motion prediction on dynamic multileaf collimator-based four-dimensional radiation delivery

    International Nuclear Information System (INIS)

    The synchronization of dynamic multileaf collimator (DMLC) response with respiratory motion is critical to ensure the accuracy of DMLC-based four dimensional (4D) radiation delivery. In practice, however, a finite time delay (response time) between the acquisition of tumor position and multileaf collimator response necessitates predictive models of respiratory tumor motion to synchronize radiation delivery. Predicting a complex process such as respiratory motion introduces geometric errors, which have been reported in several publications. However, the dosimetric effect of such errors on 4D radiation delivery has not yet been investigated. Thus, our aim in this work was to quantify the dosimetric effects of geometric error due to prediction under several different conditions. Conformal and intensity modulated radiation therapy (IMRT) plans for a lung patient were generated for anterior-posterior/posterior-anterior (AP/PA) beam arrangements at 6 and 18 MV energies to provide planned dose distributions. Respiratory motion data was obtained from 60 diaphragm-motion fluoroscopy recordings from five patients. A linear adaptive filter was employed to predict the tumor position. The geometric error of prediction was defined as the absolute difference between predicted and actual positions at each diaphragm position. Distributions of geometric error of prediction were obtained for all of the respiratory motion data. Planned dose distributions were then convolved with distributions for the geometric error of prediction to obtain convolved dose distributions. The dosimetric effect of such geometric errors was determined as a function of several variables: response time (0-0.6 s), beam energy (6/18 MV), treatment delivery (3D/4D), treatment type (conformal/IMRT), beam direction (AP/PA), and breathing training type (free breathing/audio instruction/visual feedback). Dose difference and distance-to-agreement analysis was employed to quantify results. Based on our data, the

  2. Impact of delineator and delineating criteria on the target delineation of the peripheral lung cancer based on four-dimensional computed tomography

    International Nuclear Information System (INIS)

    Objective: To investigate the impact of delineator and delineating criteria on the target delineation of the peripheral lung cancer based on four-dimensional computed tomography (4D-CT). Methods: The 4D simulation CT images of twelve patients with peripheral lung cancer were selected. Before and after the establishment of the target delineation criteria, six radiation oncologists were asked to delineate the targets based on 4D-CT images at the end-inhalation phase (0%),end-exhalation phase (50%),and three-dimensional computed tomography (3D-CT) images respectively.The delineated targets were denominated as GTV0, GTV50, GTV3D. IGTVIN+EX was created by combining GTV0 and GTV50. IGTVMIP was delineated based on the maximum intensity projection (MIP) of 4D-CT. The inter-and intra-observer variability before and after the establishment of the delineation criteria was compared. Results: The mean coefficients of variation of GTV0, GTV50, GTV3D, IGTVMIP and IGTVIN+EX delineated by the six delineators before and after the establishment of the delineation criteria were 0.50 ± 0.25 vs 0.24 ±0.10, 0.52 ±0.38 vs 0.26 ±0.12, 0.45 ±0.19 vs 0.20 ±0.07, 0.54 ±0.27 vs 0.23 ±0.09 and 0.44±0.23 vs 0.26 ±0.09, respectively. The differences were statistically significant (t=3.38, 2.44, 3.60, 4.20, 3.11, P<0.05). No statistically significant difference was found in the volume of the same target for GTV0, GTV50, GTV3D, IGTVMIP and IGTVIN+EX delineated by the six oncologists before and after the establishment of the delineation criteria. For delineator 3 and 6, the differences of GTV0, GTV50, IGTVIN+EX before and after establishment of the delineation criteria were statistically significant (t=2.46, 2.91, 3.28, P<0.05; t=2.40, 2.79, 3.22, P<0.05). For delineator 4, the differences of GTV0, GTV50, IGTVIN+EX, IGTVMIP, GTV3D before and after establishment of the delineation criteria were statistically significant (t=2.70, 3.21, 3.04, 3.99, 3.00, P<0.05). Conclusions: The unified

  3. Comparison of planning target volumes based on three-dimensional CT and four-dimensional CT simulation images of non-small-cell lung cancer

    International Nuclear Information System (INIS)

    Objective: To compare the positional and volumetric differences of planning target volumes (PTVs) based on axial three-dimensional CT (3D-CT) and four-dimensional CT (4D-CT) for the primary tumor of non-small cell lung cancer (NSCLC). Methods: Sixteen NSCLC patients with lesions located in the upper lobe and 12 patients with lesions in middle and lower lobes, totally 28 patients, initially underwent three-dimensional CT scans followed by 4D-CT scans of the thorax under normal free breathing. PTVvector was defined on gross tumor volume (GTV) contoured on 3D-CT and its motion vector. The clinical target volumes (CTVs) were created by adding 7 mm to GTVs, then, internal target volume (ITVs) were produced by enlarging CTVs isotropically based on the individually measured amount of motion in the 4D-CT, lastly, PTVs were created by adding 3 mm setup margin to ITVs. PTV4D was defined on the fusion of CTVs on all phases of the 4D data. The CTV wag generated by adding 7 mm to the GTV on each phase, then, PTVs were produced by fusing CTVs on 10 phases and adding 3 mm setup margin. The position of the target center, the volume of target and the degree of inclusion (DI) were compared reciprocally between the PTVvector and the PTV4D The difference of the position, volume and degree of inclusion of the targets between PTVvector and PTV4D were compared, and the relevance between the relative characters of the targets and the three-dimensional vector was analyzed based on the groups of the patients. Results: The median of the 3 D motion vector for the lesions in the upper lobe was 2.8 mm, significantly lower than that for the lesions in the middle and lower lobe (7.0 mm, z=-3.485, P<0.05). In the upper lobe group there was only significant spatial difference between the PTVvector and PTV4D targets in the center coordinate at the x axe (z=-2.010, P<0.05), while in the middle and lower lobes there was only significant spatial difference between the PTVvector and PTV4D targets in the

  4. A method to quantify and assess the dosimetric and clinical impact resulting from the heterogeneity correction in radiotherapy for lung cancer

    Directory of Open Access Journals (Sweden)

    Abdulhamid Chaikh

    2014-02-01

    dose prescriptions when switching the dose calculation algorithm from the PBC to PBC-MB.------------------------------------------------------Cite this article as: Chaikh A, Giraud J, Balosso J. A method to quantify and assess the dosimetric and clinical impact resulting from the heterogeneity correction in radiotherapy for lung cancer. Int J Cancer Ther Oncol 2014; 2(1:020110.DOI: http://dx.doi.org/10.14319/ijcto.0201.10

  5. Assessment of the effect of beam modifiers on skin dose for external beam radiotherapy using Gafchromic EBT2 film

    International Nuclear Information System (INIS)

    The purpose of this study was to assess the effect of different beam modifiers on the skin dose for 60Co and 15 MV photon beams. Skin doses were measured for solid water (PMMA) phantoms with Gafchromic films. It was observed that, skin dose for all the beam modifiers as well as that for the open beams increases as field size increases. At SSD of 80 cm, skin doses for 10 x 10 cm2 and 25 x 25 cm2 were, 36.9%, and 61.8% respectively for the 60Co unit. It was observed that, for a particular field size, skin dose for the 15 MV photon beam was much lower than that for 60Co beam, which gives an advantage of using the 15 MV photon beam over 60Co beam. As SSD increases skin dose reduces for both 60Co and 15 MV photon beams. For wedged fields (with 600 motorized wedge, it was found that there were very little effects on skin dose for smaller fields but significant effects for the larger fields (≥15 x 15 cm2) as compared with open beams for the 15 MV photon beam. Skin dose for bolus was higher compared with that of open beam and were 57.4% and 73.8% for 10 x 10 cm2 and 20 x 20 cm2 at 100 cm SSD respectively. For 60Co beam, the physical wedges and the 1.5 cm thickness compensator greatly reduced skin doses as compared to all the other beam modifiers. The skin doses for 10 × 10 cm2 field were 21.3%, 19.4%, 18.7%, 19.1% and 23.6% for 150, 300, 450, 600 and the 1.5 cm thickness compensators respectively, at SSD of 80 cm). These compared with 35.4% and 33.7% for the tray and open fields at the same SSD and field size as those for the wedges and compensator above. Skin doses reduced as the compensator thickness was increased. (au)

  6. Optimal beam arrangement for pulmonary ventilation image-guided intensity-modulated radiotherapy for lung cancer

    OpenAIRE

    Wang, Ruihao; Zhang, Shuxu; YU, HUI; Lin, Shengqu; Zhang, Guoqian; Tang, Rijie; Qi, Bin

    2014-01-01

    Background The principal aim of this study was to evaluate the feasibility of incorporating four-dimensional (4D)-computed tomography (CT)-based functional information into treatment planning and to evaluate the potential benefits of individualized beam setups to better protect lung functionality in patients with non-small cell lung cancer (NSCLC). Methods Peak-exhale and peak-inhale CT scans were carried out in 16 patients with NSCLC treated with intensity-modulated radiotherapy (IMRT). 4D-C...

  7. Self-assessed health-related quality of life (HRQOL) in men currently being treated for prostate cancer (PC) with radiotherapy

    International Nuclear Information System (INIS)

    Purpose/Objective: A questionnaire was designed to assess three dimensions of HRQOL symptoms known to be important for PC patients from clinical evidence and the literature: bowel function (BF), urinary function (UF), and sexual function (SF). This questionnaire was tested for reliability and validity for patients currently receiving radiotherapy for PC. There has been some suggestion that patients can suffer along several dimensions of HRQOL, yet not feel that their lives are adversely affected by these apparent impairment. Each of the HRQOL dimensions was related to a question asking directly how bothersome the reported symptoms were perceived to be. Materials and Methods: A six-page questionnaire was given to patients during treatment visits for radiation therapy for PC. The questionnaire design is based on clinical experience and a literature review to assess three HRQOL dimensions using, Likert-type questions: BF (12 items), UF (11 items), and SF (9 items), as well as a single question for each asking about how bothersome the reported symptoms are to the patient. Items in each section were analyzed with principle components factor analysis to identify meaningful sub-scales. Items found to have high factor loadings were grouped together to form scales, and the reliability and validity of the created scales was assessed. The scale scores were used to assess whether increased symptoms resulted in an increase in the perceived 'bothersomeness' to patients from the symptoms. Results: For the 62 cases, sub-scales were identified in each dimension from the factor analysis. For BF, sub-scales were identified: an 'urgency' scale (4 items), a 'daily living' scale (3 items), and single 'blood' item; for UF, sub-scales were identified for an 'urgency' scale (4 items), a 'weakness of urinary stream' scale (3 items), and a single 'blood' item; for SF, sub-scales were identified for an 'interest/satisfaction' scale (5 items) and for an 'impotence' scale (3 items). Reliability

  8. Radiotherapy of anal carcinomas

    International Nuclear Information System (INIS)

    Report is given on radiotherapy of anal carcinomas. Own experiences and a review of the recent literature are presented. Prior to surgery radiotherapy with high energy electrons in combination with chemotherapy is in the foreground. Especially in cloacogenous carcinoma no residual tumor was found after preliminary irradiation. Our recommended conception of post-operative radiotherapy of the regional lymphatic draining vessels is outlined. (orig./MG)

  9. Clinical Progress in Four-Dimensional Ultrasound in the Prenatal Diagnosis of Fetal Echocardiogram%四维超声在胎儿心脏畸形诊断中的应用

    Institute of Scientific and Technical Information of China (English)

    胡波; 胡兵

    2012-01-01

    复杂先天性心脏畸形的产前诊断较困难,二维超声心动图是胎儿心脏畸形产前诊断的基本检查方法.近年来,四维超声在胎儿心脏产前筛查中的应用发展迅速,通过时间空间相关成像(STIC)等动态显示模式,可实时动态显示胎儿心脏三维容积信息,更直观显示心房、心室和大动脉的解剖结构和空间关系,并能评估胎儿心脏容积等.作者拟就四维超声在胎儿心脏畸形诊断中的应用价值,综述如下.%The diagnosis of complex prenatal congenital heart diseases is difficult.Two dimensional echocardiogram is the gold standard for prenatal imaging of fetal heart.In recent years,four-dimensional echocardiogram has been developing rapidly for the diagnosis of fetal congenital heart diseases.Several developments of four-dimensional imaging techniques facilitate the application in clinical settings.The application of four-dimensional technology appears to be helpful for the understanding of cardiac anatomy,vascular development and cardiac function.Four-dimensional echocardiogram in the diagnosis of fetal congenital heart diseases opens an entirely new array of diagnostic modalities in clinical practice.

  10. Stage report of the national radiotherapy survey committee May 2009

    International Nuclear Information System (INIS)

    This report proposes an assessment of the impact of the national radiotherapy measures present in the road map (November 2007 - March 2009) and describes the creation of a national support unit to manage the operating difficulties of 27 radiotherapy centres. It comments how a transition period between 2009 and 2011 must accompany radiotherapy before the implementation of opposable agreement criteria in 2011, notably through an improvement of recruitment, a support to cooperation between radiotherapy centres, the implementation of a radio-vigilance unit. Finally, it briefly discusses how to prepare the 2011-2013 period

  11. Quality Assurance in Radiotherapy

    Science.gov (United States)

    Mckenzie, Alan

    A common feature of the Radiotherapy Centres where there have been major accidents involving incorrect radiotherapy treatment is that they did not operate good Quality Assurance systems. A Quality Assurance system is sometimes called a Quality Management system, and it is designed to give assurance that quality standards are being met. One of the "spin offs" from operating a Quality Management system is that it reduces the likelihood of a radiotherapy accident. A detailed account of how to set up a quality system in radiotherapy has been given in an ESTRO booklet.2

  12. Radiotherapy of Cervical Cancer.

    Science.gov (United States)

    Vordermark, Dirk

    2016-01-01

    Curative-intent radical radiotherapy of cervical cancer consists of external-beam radiotherapy, brachytherapy, and concomitant chemotherapy with cisplatin. For each element, new developments aim to improve tumor control rates or treatment tolerance. Intensity-modulated radiotherapy (IMRT) has been shown to reduce gastrointestinal toxicity and can be used to selectively increase the radiotherapy dose. Individualized, image-guided brachytherapy enables better adaptation of high-dose volumes to the tumor extension. Intensification of concomitant or sequential systemic therapy is under evaluation. PMID:27614991

  13. Stereotactic radiotherapy for vestibular schwannoma

    DEFF Research Database (Denmark)

    Muzevic, Dario; Legcevic, Jelena; Splavski, Bruno;

    2014-01-01

    BACKGROUND: Vestibular schwannomas (acoustic neuromas) are common benign tumours that arise from the Schwann cells of the vestibular nerve. Management options include observation with neuroradiological follow-up, microsurgical resection and stereotactic radiotherapy. OBJECTIVES: To assess...... the effect of stereotactic radiotherapy compared to observation, microsurgical resection, any other treatment modality, or a combination of two or more of the above approaches for vestibular schwannoma. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials; PubMed; EMBASE; CINAHL...... resection or any other possible treatment or combination of treatments in patients with a cerebellopontine angle tumour up to 3 cm in diameter, presumed to be a vestibular schwannoma. DATA COLLECTION AND ANALYSIS: We used the standard methodological procedures expected by The Cochrane Collaboration. MAIN...

  14. Assessment of image quality and dose calculation accuracy on kV CBCT, MV CBCT, and MV CT images for urgent palliative radiotherapy treatments.

    Science.gov (United States)

    Held, Mareike; Cremers, Florian; Sneed, Penny K; Braunstein, Steve; Fogh, Shannon E; Nakamura, Jean; Barani, Igor; Perez-Andujar, Angelica; Pouliot, Jean; Morin, Olivier

    2016-01-01

    A clinical workflow was developed for urgent palliative radiotherapy treatments that integrates patient simulation, planning, quality assurance, and treatment in one 30-minute session. This has been successfully tested and implemented clinically on a linac with MV CBCT capabilities. To make this approach available to all clin-ics equipped with common imaging systems, dose calculation accuracy based on treatment sites was assessed for other imaging units. We evaluated the feasibility of palliative treatment planning using on-board imaging with respect to image qual-ity and technical challenges. The purpose was to test multiple systems using their commercial setup, disregarding any additional in-house development. kV CT, kV CBCT, MV CBCT, and MV CT images of water and anthropomorphic phantoms were acquired on five different imaging units (Philips MX8000 CT Scanner, and Varian TrueBeam, Elekta VersaHD, Siemens Artiste, and Accuray Tomotherapy linacs). Image quality (noise, contrast, uniformity, spatial resolution) was evalu-ated and compared across all machines. Using individual image value to density calibrations, dose calculation accuracies for simple treatment plans were assessed for the same phantom images. Finally, image artifacts on clinical patient images were evaluated and compared among the machines. Image contrast to visualize bony anatomy was sufficient on all machines. Despite a high noise level and low contrast, MV CT images provided the most accurate treatment plans relative to kV CT-based planning. Spatial resolution was poorest for MV CBCT, but did not limit the visualization of small anatomical structures. A comparison of treatment plans showed that monitor units calculated based on a prescription point were within 5% difference relative to kV CT-based plans for all machines and all studied treatment sites (brain, neck, and pelvis). Local dose differences > 5% were found near the phantom edges. The gamma index for 3%/3 mm criteria was ≥ 95% in most

  15. The place radiotherapy alone with respect to surgery and radiotherapy in locally advanced vulva cancers; Place de la radiotherapie seule par rapport a la chirurgie et la radiotherapie dans les cancers vulvaires localement evolues

    Energy Technology Data Exchange (ETDEWEB)

    Mansouri, S.; Naim, A.; Moukhlissi, M.; Tawfik, N.; Bouchbika, Z.; Benchekroun, N.; Jouhadi, H.; Sahraoui, S.; Benider, A. [Centre de radiotherapie-oncologie, centre hospitalier universitaire, Ibn-Rochd, Casablanca (Morocco)

    2011-10-15

    The author report a study which aimed at evaluating the place or radiotherapy associated with surgery and of radiotherapy without surgery when taking into care locally advanced vulva cancers. The study is based on 46 cases. After 24 months, different aspects, such as recurrence and survival, have been assessed. It appears that there is no survival difference without recurrences between both sets. Short communication

  16. The IAEA quality audits for radiotherapy

    International Nuclear Information System (INIS)

    The IAEA, jointly with the World Health Organization (WHO), for over 40 years has operated a dosimetry audit service for radiotherapy using thermoluminescent dosimeters (TLD). The service is known as the IAEA/WHO TLD postal dose audits and it is one of the oldest dosimetry services in the world. To-date, the calibration of approximately 8000 radiotherapy beams in 1700 cancer centres in 120 countries have been audited through this service. An integral part of the auditing process is resolving discrepancies in the beam calibrations that are discovered. The discrepancies are followed-up by the IAEA and local experts, and their causes are traced, understood and corrected. Significant improvements have been observed in dosimetry practices in radiotherapy centres worldwide. In its early years, the IAEA/WHO TLD postal dose audit service recorded approximately 50% audited centres had the adequate beam calibration used for cancer treatment. The provision of regular auditing programme over long time enables the IAEA to document that several radiotherapy centres have improved their abilities to accurately deliver the radiation dose. The percentage of acceptable results has reached 96% at present. However, 4% of the poor results remain uncorrected either due to a failure to respond to the IAEA/WHO efforts or due to local problems that could not be resolved without allocation of appropriate resources. Some centres work within practical limitations such as insufficient availability of qualified medical physicists or lack of adequate dosimetry equipment, which compromises quality. These inadequacies have to be addressed locally. Another dosimetry audit programme for treatment planning in external beam radiotherapy, which has been developed by the IAEA, called TPS audit, is based on a semi-anthropomorphic phantom. It assesses the radiotherapy workflow for conformal techniques, from patient data acquisition and computerized treatment planning to dose delivery. The IAEA is

  17. SU-E-J-179: Assessment of Tumor Volume Change and Movement During Stereotactic Body Radiotherapy (SBRT) for Lung Cancer: Is Adaptive Radiation Therapy (ART) Necessary?

    International Nuclear Information System (INIS)

    Purpose: Delineation of gross tumor volumes (GTVs) is important for stereotactic body radiotherapy (SBRT). However, tumor volume changes during treatment response. Here, we have investigated tumor volume changes and movement during SBRT for lung cancer, as a means of examining the need for adaptive radiation therapy (ART). Methods: Fifteen tumors in 15 patients with lung cancer were treated with SBRT (total dose: 60 Gy in 4 fractions). GTVs were obtained from cone-beam computed tomography scans (CBCT1–4) taken before each of the 4 fractions was administered. GTVs were delineated and measured by radiation oncologists using a treatment planning system. Variance in the tumor position was assessed between the planning CT and the CBCT images. To investigate the dosimetric effects of tumor volume changes, planning CT and CBCT4 treatment plans were compared using the conformity index (CI), homogeneity index (HI), and Paddick’s index (PCI). Results: The GTV on CBCT1 was employed as a baseline for comparisons. GTV had decreased by a mean of 20.4% (range: 0.7% to 47.2%) on CBCT4. Most patients had smaller GTVs on CBCT4 than on CBCT1. The interfractional shifts of the tumor position between the planning CT and CBCT1–4 were as follows: right-left, −0.4 to 1.3 mm; anterior-posterior, −0.8 to 0.5 mm; and superiorinferior, −0.9 to 1.1 mm. Indices for plans from the planning CT and CBCT4 were as follows: CI = 0.94±0.02 and 1.11±0.03; HI= 1.1±0.02 and 1.10±0.03; and PCI = 1.35±0.16 and 1.11±0.02, respectively. Conclusion: CI, HI, and PCI did not differ between the planning CT and CBCTs. However, daily CBCT revealed a significant decrease in the GTV during lung SBRT. Furthermore, there was an obvious interfractional shift in tumor position. Using ART could potentially lead to a reduced GTV margin and improved regional tumor control for lung cancer patients with significantly decreased GTV

  18. Four and five dimensional radiotherapy with reference to prostate cancer - definitions, state of the art and further directions - an overview

    International Nuclear Information System (INIS)

    Radiotherapy (RT) always requires a compromise between tumor control and normal tissue side-effects. Technical innovation in radiation therapy (RT), such as three dimensional RT, is now established. Concerning prostate cancer (PC), it is reasonable to assume that RT of PC will increase in the future. The combination of small margins, a movable target (prostate), few fractions and high doses will probably demand dynamically positioning systems and in real time. This is called four dimensional radiotherapy (4DRT). Moreover, biological factors must be included in new treatments such as hypofractionation schedules. This new era is called five dimensional radiotherapy, 5DRT. In this paper we discuss new concepts in RT in respect to PC

  19. 3.4 Radiotherapy

    Science.gov (United States)

    Kramer, H.-M.; Selbach, H.-J.; Vatnitsky, S.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Section '3.4 Radiotherapy' of the Chapter '3 Dosimetry in Diagnostic Radiology and Radiotherapy' with the contents:

  20. Training logbook for radiotherapy.

    NARCIS (Netherlands)

    Hunter, R.; Maciejewski, B.; Leer, J.W.H.; Kinay, M.; Heeren, G.

    2004-01-01

    AIM: To develop a structured logbook for trainees in the medical specialty of radiotherapy with Europe that records the increasing experience throughout their training period. MATERIAL AND METHODS: A working party appointed by the European Board of Radiotherapy developed a draft version of a Europea

  1. Antitumor radiotherapy in children

    International Nuclear Information System (INIS)

    The philosophy is outlined of the therapy of malignant tumors in children, including Hodgkin type lymphomas and non-Hodgkin tumors, such as Wilm's tumor. The role of radiotherapy is defined and discussed in the comprehensive management of children using a combined radiotherapy-chemotherapy system. (L.O.). 5 refs

  2. [Radiotherapy of skin cancers].

    Science.gov (United States)

    Hennequin, C; Rio, E; Mahé, M-A

    2016-09-01

    The indications of radiotherapy for skin cancers are not clearly defined because of the lack of randomised trials or prospective studies. For basal cell carcinomas, radiotherapy frequently offers a good local control, but a randomized trial showed that surgery is more efficient and less toxic. Indications of radiotherapy are contra-indications of surgery for patients older than 60, non-sclerodermiform histology and occurring in non-sensitive areas. Adjuvant radiotherapy could be proposed to squamous cell carcinomas, in case of poor prognostic factors. Dose of 60 to 70Gy are usually required, and must be modulated to the size of the lesions. Adjuvant radiotherapy seems beneficial for desmoplastic melanomas but not for the other histological types. Prophylactic nodal irradiation (45 to 50Gy), for locally advanced tumours (massive nodal involvement), decreases the locoregional failure rate but do not increase survival. Adjuvant radiotherapy (50 to 56Gy) for Merckel cell carcinomas increases also the local control rate, as demonstrated by meta-analysis and a large epidemiological study. Nodal areas must be included, if there is no surgical exploration (sentinel lymph node dissection). Kaposi sarcomas are radiosensitive and could be treated with relatively low doses (24 to 30Gy). Also, cutaneous lymphomas are good indications for radiotherapy: B lymphomas are electively treated with limited fields. The role of total skin electron therapy for T-lymphomas is still discussed; but palliative radiotherapy is very efficient in case of cutaneous nodules. PMID:27522189

  3. To understand radiotherapy

    International Nuclear Information System (INIS)

    Dealing with the use of radiotherapy for adults, this guide indicates when a radiotherapy is suggested, how it acts, how the treatment is chosen, which are the professionals involved. It describes how an external radiotherapy takes place and its various techniques, the different types of side effects (general, specific to the treated zone, late effects). It indicates which organs can be treated by curie-therapy, the different curie-therapy treatment modalities, how a curie-therapy takes place and which are its side effects. It outlines how to better cope with radiotherapy (how to be supported, the important role of relatives, everyday life questions, rights). It indicates and comments the different measures adopted for the safety and quality of radiotherapy

  4. Radiotherapy for pain management of bone metastases

    International Nuclear Information System (INIS)

    Purpose: This is the first Brazilian study intended to evaluate the response of pain relief with radiotherapy in three different fractionation and the clinical differences in managing pain in patients with painful bone metastases. Methods: Prospective study of patients with painful bone metastases referred to the Radiotherapy Sector of the Hospital de Cancer de Barretos for pain-relieving radiotherapy between March and December 2010. It is known that radiotherapy seems to alter the activation of osteoclast-mediated bone resorption, relieving pain in cases of painful bone metastases. Patients were assessed in relation to the status of pain intensity before and after the initiation of radiotherapy. Either a single fraction of 8Gy, five fractions of 4Gy or ten fractions of 3Gy were given. A visual analog scale (VAS) was applied by doctors, nurses and nursing technicians to assess pain intensity at each session of radiotherapy, and follow-up at 8, 30 and 90 days from the end of treatment. Results: We evaluated 92 consecutive patients, 48 male and 44 female, with a median age of 58 years. We found that 14% of patients referred from the Palliative Care or Clinical Oncology sectors need better pharmacological analgesia due to severe pain, compared with 40.5% of patients from the other sectors (p = 0.004). We also found that the onset of pain relief to patients receiving 10 fractions of 300cGy analgesia without changing the pre-radiotherapy analgesia occurred with significance after the fifth fraction. Improvement in pain experienced within 90 days of follow-up was found in eighty percent of patients, independent of fractionated radiotherapy, site of metastases and the clinical condition of the patient. Discussion/Conclusion: The Palliative Care and Clinical Oncology sectors expressed greater concern in regards to analgesia for the patient with painful bone metastases. Radiotherapy is an effective pain-relieving treatment in different fractionation studied, even though the

  5. Radiotherapy for pain management of bone metastases

    Energy Technology Data Exchange (ETDEWEB)

    Rezende Junior, Ismar de; Mattos, Marcos Duarte de; Nakamura, Ricardo; Lemes Junior, Joaquim; Vanzelli, Talita Lozano, E-mail: rezende.med@terra.com.br [Radioterapia do Hospital de Cancer de Barretos, SP (Brazil)

    2011-07-01

    Purpose: This is the first Brazilian study intended to evaluate the response of pain relief with radiotherapy in three different fractionation and the clinical differences in managing pain in patients with painful bone metastases. Methods: Prospective study of patients with painful bone metastases referred to the Radiotherapy Sector of the Hospital de Cancer de Barretos for pain-relieving radiotherapy between March and December 2010. It is known that radiotherapy seems to alter the activation of osteoclast-mediated bone resorption, relieving pain in cases of painful bone metastases. Patients were assessed in relation to the status of pain intensity before and after the initiation of radiotherapy. Either a single fraction of 8Gy, five fractions of 4Gy or ten fractions of 3Gy were given. A visual analog scale (VAS) was applied by doctors, nurses and nursing technicians to assess pain intensity at each session of radiotherapy, and follow-up at 8, 30 and 90 days from the end of treatment. Results: We evaluated 92 consecutive patients, 48 male and 44 female, with a median age of 58 years. We found that 14% of patients referred from the Palliative Care or Clinical Oncology sectors need better pharmacological analgesia due to severe pain, compared with 40.5% of patients from the other sectors (p = 0.004). We also found that the onset of pain relief to patients receiving 10 fractions of 300cGy analgesia without changing the pre-radiotherapy analgesia occurred with significance after the fifth fraction. Improvement in pain experienced within 90 days of follow-up was found in eighty percent of patients, independent of fractionated radiotherapy, site of metastases and the clinical condition of the patient. Discussion/Conclusion: The Palliative Care and Clinical Oncology sectors expressed greater concern in regards to analgesia for the patient with painful bone metastases. Radiotherapy is an effective pain-relieving treatment in different fractionation studied, even though the

  6. Japanese patterns of care study of postoperative radiotherapy for uterine cervical cancer. The assessment of treatment process of the 1995-2005 surveys

    International Nuclear Information System (INIS)

    The purpose of the study is to evaluate Japanese national practice patterns for patients undergoing postoperative radiotherapy for uterine cervical cancer. The Japan Patterns of Care Study (JPCS) collected the data of patients who were treated postoperative radiation therapy between 1995-1997 (JPCS 95-97), 1999-2001 (JPCS 99-01) and 2003-2005 (JPCS 03-05). Over 80% of patients were treated with external beam RT (ERT). ERT dose ranged from 45 to 50.4 Gy for over 70% of patients. The utilization rates of CT-simulation, multi-leaf collimator and over 10 MV photon energy were increased among three JPCS surveys. Positive lymph nodes, capillary lymphatic space tumor involvement and deep stromal invasion was the main reasons of adaptation of the postoperative radiotherapy. Compared with the previous 2 PCS studies, the patient who received concurrent chemoradiation was increased in JPCS 03-05 (6, 9% to 25%). (author)

  7. Differential risk assessments from five hypoxia specific assays: The basis for biologically adapted individualized radiotherapy in advanced head and neck cancer patients

    DEFF Research Database (Denmark)

    Nordsmark, Marianne; Eriksen, Jesper Grau; Gebski, Val; Alsner, Jan; Horsman, Michael Robert; Overgaard, Jens

    2007-01-01

    PURPOSE: Hypoxia adversely relates with prognosis in human tumours. Five hypoxia specific predictive marker assays were compared and correlated with definitive radiotherapy. PATIENTS AND METHODS: Sixty-seven patients with advanced head and neck carcinomas were studied for pre-treatment plasma...... osteopontin measured by ELISA, tumour oxygenation status using pO(2) needle electrodes and tumour osteopontin, hypoxia inducible factor 1alpha (HIF-1alpha) and carboxyanhydrase 9 (CA9) by immunohistochemistry. The primary treatment was radiotherapy and the hypoxic radiosensitizer nimorazole. Loco......-regional tumour control was evaluated at 5 years. RESULTS: All five markers showed inter-tumour variability. Inter-marker correlations were inconsistent. Only plasma osteopontin inversely correlated with median tumour pO(2), (p=0.02, r=0.28) and CA9 correlated with HIF-1alpha (p<0.01, r=0.45). In Kaplan...

  8. Translation and cross-cultural adaptation into Brazilian Portuguese of the Vanderbilt Head and Neck Symptom Survey version 2.0 (VHNSS 2.0 for the assessment of oral symptoms in head and neck cancer patients submitted to radiotherapy

    Directory of Open Access Journals (Sweden)

    Eliane Marçon Barroso

    2015-12-01

    Full Text Available ABSTRACT INTRODUCTION: Patients submitted to radiotherapy for the treatment of head and neck cancer have several symptoms, predominantly oral. The Vanderbilt Head and Neck Symptom Survey version 2.0 is an American tool developed to evaluate oral symptoms in head and neck cancer patients submitted to radiotherapy. OBJECTIVE: The aim of the present study was to translate the Vanderbilt Head and Neck Symptom Survey version 2.0 into Brazilian Portuguese and cross-culturally adapt this tool for subsequent validation and application in Brazil. METHODS: A method used for the translation and cultural adaptation of tools, which included independent translations, synthesis of the translations, back-translations, expert committee, and pre-test, was used. The pre-test was performed with 37 head and neck cancer patients, who were divided into four groups, to assess the relevance and understanding of the assessed items. Data were submitted to descriptive statistical analysis. RESULTS: The overall mean of the content validity index was 0.79 for semantic and idiomatic equivalence, and it was higher than 0.8 for cultural and conceptual equivalence. The cognitive interview showed that patients were able to paraphrase the items, and considered them relevant and easily understood. CONCLUSION: The tool was translated and cross-culturally adapted to be used in Brazil. The authors believe this translation is suited for validation.

  9. SU-E-J-154: Image Quality Assessment of Contrast-Enhanced 4D-CT for Pancreatic Adenocarcinoma in Radiotherapy Simulation

    International Nuclear Information System (INIS)

    Purpose: This study presents quantitative and qualitative assessment of the image qualities in contrast-enhanced (CE) 3D-CT, 4D-CT and CE 4D-CT to identify feasibility for replacing the clinical standard simulation with a single CE 4D-CT for pancreatic adenocarcinoma (PDA) in radiotherapy simulation. Methods: Ten PDA patients were enrolled and underwent three CT scans: a clinical standard pair of CE 3D-CT immediately followed by a 4D-CT, and a CE 4D-CT one week later. Physicians qualitatively evaluated the general image quality and regional vessel definitions and gave a score from 1 to 5. Next, physicians delineated the contours of the tumor (T) and the normal pancreatic parenchyma (P) on the three CTs (CE 3D-CT, 50% phase for 4D-CT and CE 4D-CT), then high density areas were automatically removed by thresholding at 500 HU and morphological operations. The pancreatic tumor contrast-to-noise ratio (CNR), signal-tonoise ratio (SNR) and conspicuity (C, absolute difference of mean enhancement levels in P and T) were computed to quantitatively assess image quality. The Wilcoxon rank sum test was used to compare these quantities. Results: In qualitative evaluations, CE 3D-CT and CE 4D-CT scored equivalently (4.4±0.4 and 4.3±0.4) and both were significantly better than 4D-CT (3.1±0.6). In quantitative evaluations, the C values were higher in CE 4D-CT (28±19 HU, p=0.19 and 0.17) than the clinical standard pair of CE 3D-CT and 4D-CT (17±12 and 16±17 HU, p=0.65). In CE 3D-CT and CE 4D-CT, mean CNR (1.8±1.4 and 1.8±1.7, p=0.94) and mean SNR (5.8±2.6 and 5.5±3.2, p=0.71) both were higher than 4D-CT (CNR: 1.1±1.3, p<0.3; SNR: 3.3±2.1, p<0.1). The absolute enhancement levels for T and P were higher in CE 4D-CT (87, 82 HU) than in CE 3D-CT (60, 56) and 4DCT (53, 70). Conclusions: The individually optimized CE 4D-CT is feasible and achieved comparable image qualities to the clinical standard simulation. This study was supported in part by Philips Healthcare

  10. SU-E-J-154: Image Quality Assessment of Contrast-Enhanced 4D-CT for Pancreatic Adenocarcinoma in Radiotherapy Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, W; Xue, M; Patel, K; Regine, W; Wang, J; D’Souza, W; Lu, W [University of Maryland School of Medicine, Baltimore, MD (United States); Kang, M [University of Maryland School of Medicine, Baltimore, MD (United States); Yeungnam University Medical Center, Daegu, Daegu (Korea, Republic of); Klahr, P [Philips Healthcare, Highland Heights, OH (United States)

    2015-06-15

    Purpose: This study presents quantitative and qualitative assessment of the image qualities in contrast-enhanced (CE) 3D-CT, 4D-CT and CE 4D-CT to identify feasibility for replacing the clinical standard simulation with a single CE 4D-CT for pancreatic adenocarcinoma (PDA) in radiotherapy simulation. Methods: Ten PDA patients were enrolled and underwent three CT scans: a clinical standard pair of CE 3D-CT immediately followed by a 4D-CT, and a CE 4D-CT one week later. Physicians qualitatively evaluated the general image quality and regional vessel definitions and gave a score from 1 to 5. Next, physicians delineated the contours of the tumor (T) and the normal pancreatic parenchyma (P) on the three CTs (CE 3D-CT, 50% phase for 4D-CT and CE 4D-CT), then high density areas were automatically removed by thresholding at 500 HU and morphological operations. The pancreatic tumor contrast-to-noise ratio (CNR), signal-tonoise ratio (SNR) and conspicuity (C, absolute difference of mean enhancement levels in P and T) were computed to quantitatively assess image quality. The Wilcoxon rank sum test was used to compare these quantities. Results: In qualitative evaluations, CE 3D-CT and CE 4D-CT scored equivalently (4.4±0.4 and 4.3±0.4) and both were significantly better than 4D-CT (3.1±0.6). In quantitative evaluations, the C values were higher in CE 4D-CT (28±19 HU, p=0.19 and 0.17) than the clinical standard pair of CE 3D-CT and 4D-CT (17±12 and 16±17 HU, p=0.65). In CE 3D-CT and CE 4D-CT, mean CNR (1.8±1.4 and 1.8±1.7, p=0.94) and mean SNR (5.8±2.6 and 5.5±3.2, p=0.71) both were higher than 4D-CT (CNR: 1.1±1.3, p<0.3; SNR: 3.3±2.1, p<0.1). The absolute enhancement levels for T and P were higher in CE 4D-CT (87, 82 HU) than in CE 3D-CT (60, 56) and 4DCT (53, 70). Conclusions: The individually optimized CE 4D-CT is feasible and achieved comparable image qualities to the clinical standard simulation. This study was supported in part by Philips Healthcare.

  11. The utility of FDG-PET for assessing outcomes in oligometastatic cancer patients treated with stereotactic body radiotherapy: a cohort study

    OpenAIRE

    Solanki Abhishek A; Weichselbaum Ralph R; Appelbaum Daniel; Farrey Karl; Yenice Kamil M; Chmura Steven J; Salama Joseph K

    2012-01-01

    Abstract Background Studies suggest that patients with metastases limited in number and destination organ benefit from metastasis-directed therapy. Stereotactic body radiotherapy (SBRT) is commonly used for metastasis directed therapy in this group. However, the characterization of PET response following SBRT is unknown in this population. We analyzed our cohort of patients to describe the PET response following SBRT. Methods Patients enrolled on a prospective dose escalation trial of SBRT to...

  12. Long-term outcome and toxicity of hypofractionated stereotactic body radiotherapy as a boost treatment for head and neck cancer: the importance of boost volume assessment

    OpenAIRE

    Lee, Dong Soo; Kim, Yeon Sil; Cheon, Jae Seok; Song, Jin Ho; SON, Seok Hyun; Jang, Ji Sun; Kang, Young Nam; Kang, Jing Hyoung; Jung, So Lyoung; Yoo, Ie Ryung; Jang, Hong Seok

    2012-01-01

    Background The aim of this study was to report the long-term clinical outcomes of patients who received stereotactic body radiotherapy (SBRT) as a boost treatment for head and neck cancer. Materials and methods Between March 2004 and July 2007, 26 patients with locally advanced, medically inoperable head and neck cancer or gross residual tumors in close proximity to critical structures following head and neck surgery were treated with SBRT as a boost treatment. All patients were initially tre...

  13. Long-term outcome and toxicity of hypofractionated stereotactic body radiotherapy as a boost treatment for head and neck cancer: the importance of boost volume assessment

    OpenAIRE

    Lee Dong; Kim Yeon; Cheon Jae; Song Jin; Son Seok; Jang Ji; Kang Young; Kang Jing; Jung So; Yoo Ie; Jang Hong

    2012-01-01

    Abstract Background The aim of this study was to report the long-term clinical outcomes of patients who received stereotactic body radiotherapy (SBRT) as a boost treatment for head and neck cancer. Materials and methods Between March 2004 and July 2007, 26 patients with locally advanced, medically inoperable head and neck cancer or gross residual tumors in close proximity to critical structures following head and neck surgery were treated with SBRT as a boost treatment. All patients were init...

  14. Changes in oxygenation during radiotherapy in carcinoma of the cervix

    International Nuclear Information System (INIS)

    Purpose: The aim of this study was to investigate changes in tumor oxygenation, assessed by polarographic needle electrode measurements, following fractionated external beam radiotherapy in carcinoma of the cervix. Methods and Materials: Normal and tumor tissue oxygenation was measured in 19 patients prior to radiotherapy and after 40-45 Gy of external beam radiotherapy delivered in 20 fractions over 4 weeks. All measurements were performed during anesthesia. Results: There was no significant difference in the level of normal tissue oxygenation pre- and post radiotherapy. The individual patient median tumor pO2 values ranged from 0 to 31 mmHg pre-radiotherapy and 1 to 61 mmHg post-radiotherapy. The mean of the 19 median pO2 values increased from 8 (SD ± 10) mmHg to 20 (± 20) mmHg following external beam radiotherapy. The increase was significant by paired Wilcoxon test (p = 0.011). There was also a significant fall in the proportion of values < 5 mmHg (p = 0.040). Although this value remained constant, or fell, in the majority of patients (15/19), it increased in 4 tumors. Tumor size pre- and post-radiotherapy did not correlate with the level of pretreatment oxygenation; neither did the change in tumor size and change in level of oxygenation. Conclusion: The level of tumor oxygenation increased in the majority of patients (15/19) following 40-45 Gy of radiotherapy in carcinoma of the cervix

  15. Advances of Precise Radiotherapy for Lung Cancer

    OpenAIRE

    Xin WANG; Xu, Feng; Wei, Yuquan

    2011-01-01

    At present lung tumor radiation therapy has entered the accurate radiotherapy era. Precise radiotherapy includes intensity modulated radiotherapy (IMRT), image-guided radiotherapy (IGRT) and stereotactic body radiotherapy (SBRT). During the process of implementing precise radiotherapy, these problems should be fully considered to ensure executing precise radiotherapy accurately: patient positioning, controlling of the lung tumor motion, selecting of image techniques, PTV margin, dose prescrip...

  16. 7-Tesla Susceptibility-Weighted Imaging to Assess the Effects of Radiotherapy on Normal-Appearing Brain in Patients With Glioma

    International Nuclear Information System (INIS)

    Purpose: To evaluate the intermediate- and long-term imaging manifestations of radiotherapy on normal-appearing brain tissue in patients with treated gliomas using 7T susceptibility-weighted imaging (SWI). Methods and Materials: SWI was performed on 25 patients with stable gliomas on a 7 Tesla magnet. Microbleeds were identified as discrete foci of susceptibility that did not correspond to vessels. The number of microbleeds was counted within and outside of the T2-hyperintense lesion. For 3 patients, radiation dosimetry maps were reconstructed and fused with the 7T SWI data. Results: Multiple foci of susceptibility consistent with microhemorrhages were observed in patients 2 years after chemoradiation. These lesions were not present in patients who were not irradiated. The prevalence of microhemorrhages increased with the time since completion of radiotherapy, and these lesions often extended outside the boundaries of the initial high-dose volume and into the contralateral hemisphere. Conclusions: High-field SWI has potential for visualizing the appearance of microbleeds associated with long-term effects of radiotherapy on brain tissue. The ability to visualize these lesions in normal-appearing brain tissue may be important in further understanding the utility of this treatment in patients with longer survival.

  17. Beam path toxicity in candidate organs-at-risk: Assessment of radiation emetogenesis for patients receiving head and neck intensity modulated radiotherapy

    International Nuclear Information System (INIS)

    Background: To investigate potential dose–response relationship between radiation-associated nausea and vomiting (RANV) reported during radiotherapy and candidate nausea/vomiting-associated regions of interest (CNV-ROIs) in head and neck (HNC) squamous cell carcinomas. Methods and material: A total of 130 patients treated with IMRT with squamous cell carcinomas of head and neck were evaluated. For each patient, CNV-ROIs were segmented manually on planning CT images. Clinical on-treatment RANV data were reconstructed by a review of the records for all patients. Dosimetric data parameters were recorded from dose–volume histograms. Nausea and vomiting reports were concatenated as a single binary “Any N/V” variable, and as a “CTC-V2+” variable. Results: The mean dose to CNV-ROIs was higher for patients experiencing RANV events. For patients receiving IMRT alone, a dose–response effect was observed with varying degrees of magnitude, at a statistically significant level for the area postrema, brainstem, dorsal vagal complex, medulla oblongata, solitary nucleus, oropharyngeal mucosa and whole brain CNV-ROIs. Conclusion: RANV is a common therapy-related morbidity facing patients receiving HNC radiotherapy, and, for those receiving radiotherapy-alone, is associated with modifiable dose to specific CNS structures

  18. Concepts of radiotherapy treatment planning

    International Nuclear Information System (INIS)

    mathematical objective functions and the optimization process searches for the best configuration of allowed beams. Optimized radiotherapy planning is the basis of intensity-modulated radiation therapy (IMRT) because this type of planning invariably results in specifying intensity distributions that are non-uniform. The character of the optimized solution depends on many factors. Some objective functions result in higher dose uniformity in the target volume. Increased target dose uniformity sometimes results in higher dose to sensitive structures. Increasing the number of beam directions results in better uniformity and lower dose to normal tissue but the improvement becomes asymptotic. The presence of abutting sensitive structures to be 'conformally avoided' and increased complexity of shape of the target volume can most benefit from larger numbers of beam directions and highly-modulated high-resolution intensity patterns. Coplanar beams are usually used for IMRT below the head because the optimization results suggest that there are limited additional benefits resulting from the use of non-coplanar IMRT fields and the selection of optimal field directions expands the solution space substantially. When sufficient numbers of beams are used the beam orientation become less important and an odd number of equally spaced beams are typically used. In the future the entire treatment delivery system including the head of the machine, the beam modifiers, the patient and couch, the portal imaging system and the bunker shielding will be included in RTP. In effect RTP will be a general computer simulation of the entire process of treatment delivery. Delivery verification systems will be linked with RTP systems so that the treatments may be adaptively modified to ensure that the whole course of therapy is being delivered correctly. Four-dimensional treatment planning will account for patient and organ motion. All treatments will be archived and linked to outcome data so that the efficacy

  19. Updates on clinical studies of selenium supplementation in radiotherapy

    International Nuclear Information System (INIS)

    To establish guidelines for the selenium supplementation in radiotherapy we assessed the benefits and risks of selenium supplementation in radiotherapy. Clinical studies on the use of selenium in radiotherapy were searched in the PubMed electronic database in January 2013. Sixteen clinical studies were identified among the 167 articles selected in the initial search. Ten articles were observational studies, and the other 6 articles reported studies on the effects of selenium supplementation in patients with cancer who underwent radiotherapy. The studies were conducted worldwide including European, American and Asian countries between 1987 and 2012. Plasma, serum or whole blood selenium levels were common parameters used to assess the effects of radiotherapy and the selenium supplementation status. Selenium supplementation improved the general conditions of the patients, improved their quality of life and reduced the side effects of radiotherapy. At the dose of selenium used in these studies (200–500 μg/day), selenium supplementation did not reduce the effectiveness of radiotherapy, and no toxicities were reported. Selenium supplementation may offer specific benefits for several types of cancer patients who undergo radiotherapy. Because high-dose selenium and long-term supplementation may be unsafe due to selenium toxicity, more evidence-based information and additional research are needed to ensure the therapeutic benefits of selenium supplementation

  20. A phantom for testing of 4D-CT for radiotherapy of small lesions

    International Nuclear Information System (INIS)

    Purpose: The use of time-resolved four-dimensional computed tomography (4D-CT) in radiotherapy requires strict quality assurance to ensure the accuracy of motion management protocols. The aim of this work was to design and test a phantom capable of large amplitude motion for use in 4D-CT, with particular interest in small lesions typical for stereotactic body radiotherapy. Methods: The phantom of “see-saw” design is light weight, capable of including various sample materials and compatible with several surrogate marker signal acquisition systems. It is constructed of polymethylmethacrylate (Perspex) and its movement is controlled via a dc motor and drive wheel. It was tested using two CT scanners with different 4D acquisition methods: the Philips Brilliance Big Bore CT (helical scan, pressure belt) and a General Electric Discovery STE PET/CT (axial scan, infrared marker). Amplitudes ranging from 1.5 to 6.0 cm and frequencies of up to 40 cycles per minute were used to study the effect of motion on image quality. Maximum intensity projections (MIPs), as well as average intensity projections (AIPs) of moving objects were investigated and their quality dependence on the number of phase reconstruction bins assessed. Results: CT number discrepancies between moving and stationary objects were found to have no systematic dependence on amplitude, frequency, or specific interphase variability. MIP-delineated amplitudes of motion were found to match physical phantom amplitudes to within 2 mm for all motion scenarios tested. Objects undergoing large amplitude motions (>3.0 cm) were shown to cause artefacts in MIP and AIP projections when ten phase bins were assigned. This problem can be mitigated by increasing the number of phase bins in a 4D-CT scan. Conclusions: The phantom was found to be a suitable tool for evaluating the image quality of 4D-CT motion management technology, as well as providing a quality assurance tool for intercenter/intervendor testing of commercial

  1. The Value of Four-dimensional Ultrasound Combined with Two-dimensional Ultrasound in Diagnosis of Fetal Malformations%二维联合四维超声在胎儿畸形诊断中的价值

    Institute of Scientific and Technical Information of China (English)

    孙巧霞; 王云; 孙京倩; 随璐

    2014-01-01

    Objective:To investigate the value of two-dimensional ultrasound combined with four-dimensional ultrasound in the diagnosis of fetal malformation.Method:A total of 11 573 pregnant women did the examination in Qinghe County Central Hospital from April 2011 to March 2013,and the two-dimensional ultrasound were used to do the prenatal screening,and the suspect deformity children were detected by the two-dimensional ultrasound and four-dimensional ultrasound,and these result and results of the induction and follow-up were compared.Result:The total relevance ratios of the two methods were compared,and the difference was statistically significant(P<0.05).Conclusion:It should use two-dimensional ultrasound to screening firstly in the diagnosis of fetal malformations,and then it should use two-dimensional ultrasound combined with four-dimensional ultrasound as supplement.The four-dimensional ultrasound has great advances in the diagnosis of deformities in the face,extremities,spine and other surface,can improve the diagnose accordance rate of fetal malformation,has a high practical clinical value.%目的:探讨利用二维超声联合四维超声诊断胎儿畸形的临床价值。方法:选择2011年4月-2013年3月来清河县中心医院进行检查的11573例孕妇,利用二维超声对其进行产前筛查,对于疑似畸形患儿进行二维和四维超声联合检查,所得结果与引产和随访结果进行比较。结果:两种方法总检出率比较,差异有统计学意义(P<0.05)。结论:诊断胎儿畸形应首先利用二维超声进行筛查,再联合四维超声进行补充诊断。四维超声在诊断颜面部、四肢、脊柱等体表畸形方面具有明显的优势,可提高胎儿畸形的诊断符合率,具有较高的临床实用价值。

  2. Interim assessment of prospective phase Ⅱ trial evaluating efficacy of intensity-modulated radiotherapy with concurrent capecitabine for stage Ⅱ/Ⅲ gastric cancer after radical surgery

    International Nuclear Information System (INIS)

    Objective: To evaluate the preliminary efficacy and acute toxicities of intensity-modulated radiotherapy (IMRT) with concurrent capecitabine for stage Ⅱ/Ⅲ gastric cancer (AJCC 7th) after radical surgery and to decide whether to continue phase Ⅱ trial. Methods: From 2009 to 2011, 35 patients with gastric cancer (10 stage Ⅱ patients and 25 stage Ⅲ patients) were included in prospective phase Ⅱ trial to receive chemoradiotherapy. In radiotherapy, the patients received IMRT to the anastomosis,tumor bed, and regional lymph nodes at a dose of 45 Gy/25 fractions. In concurrent chemotherapy, the patients received capecitabine at 1 600 mg/m2 in two divided doses per day for 5 weeks; in adjuvant chemotherapy, the patients received fluorouracil or capecitabine ± oxaliplatin (4-8 cycles). The Kaplan-Meier method was used to calculate survival rates, and the log-rank test was used for univariate prognostic analysis. A disease-free survival (DFS) of 52.9% was used as the lower limit for continuing study. Results: With a median follow-up of 21 months, the follow-up rate was 94%. Radiotherapy was not completed in 3 patients. The 2-year DFS and overall survival (OS) were 70% and 86%, respectively. The incidence rates of grade 3 acute gastrointestinal, hematologic, and overall toxicities were 11%, 11%, and 26%, respectively. The prognostic analysis showed that signet-ring cell carcinoma and positive lymph node ratio were adverse prognostic factors for DFS, and advanced T stage (T4) was the adverse prognostic factor for OS. Conclusions: The 2-year DFS was greater than 52.9% among all patients with gastric cancer who received IMRT with concurrent capecitabine after radical surgery, and the toxicities were tolerable. Thus, phase Ⅱ trial could be continued. (authors)

  3. DICOM in Radiotherapy

    Directory of Open Access Journals (Sweden)

    A. Nikfarjam

    2007-08-01

    Full Text Available Noticeable development in achieving data from patients is acquired by means of designing a system that connects these systems: imaging, archive and monitoring systems. When several imaging devices work based on DICOM standard; they can connect to each other without any interface. There are many applications for DICOM standard in radiotherapy; however its main usage is in imaging. It has other applications such as RT Structure Set, RT Dose, RT Plan and RT Brachy Treatment. "nNow DICOM is a complete and widespread standard to use in radiotherapy. Most of the radiotherapy machines have ability to use DICOM. Before installing a new Linac, it is necessary to predict all aspects of DICOM standard in this device. Therefore, as regards to entrance of 12 Linac to Iran, it is important to have enough knowledge about it. This article is a review about development of DICOM in radiotherapy. We try to stress on DICOM applications and abstain from technological agenda.

  4. Radiotherapy cure: safety

    International Nuclear Information System (INIS)

    In radiotherapy, a precisely measured dose of ionising radiation is directed at a limited tumour area so as not to damage healthy tissues. The most important form of therapy is external radiation therapy given by means of radiotherapy equipment. The bigger the tumour, the more cancer cells it contains and the higher the radiation dose that is needed to destroy the tumour. Different cancer types respond differently to radiation. Healthy tissues also respond in different ways to radiotherapy, e.g. the reaction may come during the treatment or later. The growth of some cancer types accelerates in two to four weeks after the initiation of the therapy. This information has brought about a reduction in treatment times so as to avoid cell growth that might endanger the treatment result. The radiotherapy that is given today by specialist doctors is safe because the side effects of the treatment are well under control. (orig.)

  5. The effects of radiotherapy and surgery on the sexual function of women treated for cervical cancer

    International Nuclear Information System (INIS)

    Purpose: This study investigated the short- and medium-term effects of pelvic radiotherapy and surgery on the sexual function of women treated for cervical cancer. Methods and Materials: Sixteen women with Stages I, II, or III disease referred for radiotherapy treatment were assessed. Six had undergone prior hysterectomy. The women were assessed with questionnaires prior to radiotherapy, at completion of radiotherapy, and at 6 weeks and 14 weeks after radiotherapy treatment. The clinical findings at routine follow-up were noted. Results: The study showed significant changes in sexual activity and satisfaction as a result of treatment. This was due to a number of physical and psychological factors. The level of sexual activity was lowest at completion of radiotherapy treatment. A feeling of vaginal shortening was the most frequent reason and was more common in women who were treated with surgery and radiotherapy. Dyspareunia, bleeding, and concern of bleeding and/or recurrence were all significant factors. Conclusions: The questionnaires were an effective way of assessing women's sexual function. Radiotherapy caused sexual dysfunction in one-half of women. Combined treatment with radiotherapy and surgery results in a higher risk than radiotherapy alone. Women with cervical cancer and undergoing radiotherapy treatment require considerable counseling and support

  6. Assessment of quality of life and changes in body composition in men with localized prostate cancer on hormone therapy combined with radiotherapy prostate cancer, quality of life, body composition

    International Nuclear Information System (INIS)

    Objective: the aim of this study was to evaluate the quality of life and changes in body composition in adult men (71.3 ± 6.9 years) with prostate cancer on hormone therapy combined with radiotherapy. Methodology: to assess the quality of life of individuals, we used the 36-Item Short Form Health Survey (SF-36), which is a tool developed to survey health status in the Medical Outcomes Study. This questionnaire was applied at the beginning and six months after the start of the study. Weight was measured and the percentage of fat was estimated from an anthropometric equation from Jackson and Pollock (1978). The period of assessments and reassessments was September 2009 to October 2010. Radiotherapy was performed in other hospitals (information contained in participant's data form), as the management of patients was conducted at the oncology pharmacy of Varzea do Carmo Specialties Clinic. Results: of the eight domains of the SF-36 questionnaire, five were worse with significant differences from the first to the second assessment. They are: overall health status (p <0.01), vitality (p <0.01), functional capacity (p <0.01), social functioning (p <0.01) and pain (p <0, 01). Body weight ranged statistically significant (p <0.01) between the first evaluation (75.3 ± 12.5kg) and the second evaluation (77.4 ± 12.5kg). The same occurred with the percentage of fat, where the initial values (25.1 ± 3.8%) and final (25.8 ± 3.5%) experienced statistically significant difference (p <0.01). Conclusion: the results of this study showed that hormone therapy combined with radiotherapy led to a gain of weight and body fat percentage in the men evaluated, as well as deterioration in the quality of life of these patients. Therefore, it is necessary to continue researching this topic in order to develop strategies that mitigate the side effects of hormone therapy. The risks of hormone therapy should be evaluated and compared with gains in order to define the length of treatment

  7. Assessment of quality of life and changes in body composition in men with localized prostate cancer on hormone therapy combined with radiotherapy prostate cancer, quality of life, body composition

    Energy Technology Data Exchange (ETDEWEB)

    Pires, Daniele de Campos; Salvajoli, Joao Victor; Gagliardi, Joao Fernando; Evangelista, Alexandre Lopes; Lopes, Charles Ricardo; Cruz, Ticiane

    2014-07-01

    Objective: the aim of this study was to evaluate the quality of life and changes in body composition in adult men (71.3 ± 6.9 years) with prostate cancer on hormone therapy combined with radiotherapy. Methodology: to assess the quality of life of individuals, we used the 36-Item Short Form Health Survey (SF-36), which is a tool developed to survey health status in the Medical Outcomes Study. This questionnaire was applied at the beginning and six months after the start of the study. Weight was measured and the percentage of fat was estimated from an anthropometric equation from Jackson and Pollock (1978). The period of assessments and reassessments was September 2009 to October 2010. Radiotherapy was performed in other hospitals (information contained in participant's data form), as the management of patients was conducted at the oncology pharmacy of Varzea do Carmo Specialties Clinic. Results: of the eight domains of the SF-36 questionnaire, five were worse with significant differences from the first to the second assessment. They are: overall health status (p <0.01), vitality (p <0.01), functional capacity (p <0.01), social functioning (p <0.01) and pain (p <0, 01). Body weight ranged statistically significant (p <0.01) between the first evaluation (75.3 ± 12.5kg) and the second evaluation (77.4 ± 12.5kg). The same occurred with the percentage of fat, where the initial values (25.1 ± 3.8%) and final (25.8 ± 3.5%) experienced statistically significant difference (p <0.01). Conclusion: the results of this study showed that hormone therapy combined with radiotherapy led to a gain of weight and body fat percentage in the men evaluated, as well as deterioration in the quality of life of these patients. Therefore, it is necessary to continue researching this topic in order to develop strategies that mitigate the side effects of hormone therapy. The risks of hormone therapy should be evaluated and compared with gains in order to define the length of treatment

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    improve hemodynamic assessment. This has been a challenge because compensation of respiratory motion is difficult to achieve, but it is paramount to limit artifacts and improve accuracy. In this work we propose a self-gating technique for respiratory motion-compensation integrated into a whole-heart 4D...... precision of flux data was highly beneficial. The methodology presented here has the potential to allow a complete study of flow pathophysiology of the thoracic cardiovascular system from a single free-breathing scan....

  9. Probing into Chemical Sales Customer Service Innovation Based on Four-Dimensional Model%基于四维模型的化工销售客户服务创新探讨

    Institute of Scientific and Technical Information of China (English)

    牟慈

    2015-01-01

    服务创新是当今制造企业转型发展的新趋势,是企业获得核心竞争力的新源泉。本文通过阐述服务创新四维模型理论,尝试分析化工销售客户服务现状及存在问题,提出化工销售客户服务创新借鉴四维模型的相关建议。%Service innovation is not only the new trend of manufacturing enterprise transformational development but also the new source for enterprises to acquire core competitiveness. Through expounding on four-dimensional model theory for service innovation, the article tries out an analysis of chemical sales customer service status as well as existing problems and puts forward relevant suggestions for drawing lessons from four-dimensional model in chemical sales customer service innovation.

  10. Four-dimensional measurement of the displacement of metal clips or postoperative surgical staples during 320-multislice computed tomography scanning of gastric cancer

    International Nuclear Information System (INIS)

    To investigate the respiratory motion of metal clips or surgical staples placed in the gastric wall for planning of radiation therapy in gastric cancer patients. This study examined 15 metal markers in the gastric walls of 12 patients with gastric cancer treated with external-beam photon RT. Motion assessment was analyzed in 41 respiratory phases covering 20 s acquired with computed tomography (CT) in the RT position using 320-multislice CT. The intra-fraction displacement was assessed in the cranio-caudal (CC), antero-posterior (AP), and right-left (RL) directions. Motion in the CC direction showed a very strong correlation (R2 > 0.7) with the respiratory curve in all 15 markers. The mean (+/− SD) intra-fractional gastric motion (maximum range of displacement) was 12.5 (+/− 3.4) mm in the CC, 8.3 (+/− 2.2) mm in the AP, and 5.5 (+/− 3.0) mm in the RL direction. No significant differences in magnitude of motion were detected in the following: a) among the upper (n = 6), middle (n = 4), and lower (n = 5) stomach regions; b) between metal clips (n = 5) and surgical staples (n = 10); and c) between full (n = 9) and empty (n = 6) stomachs. Motion in primary gastric tumor was evaluated with 320-multislice CT. According to this study, the 95th percentile values from the cumulative distributions of the RL, AP, and CC direction were 6.3 mm, 9.0 mm, and 13.6 mm, respectively

  11. Changes in tumour volume and motion during radiotherapy for thoracic oesophageal cancer

    International Nuclear Information System (INIS)

    Background and purpose: Variations of target volume and position were important factors in correction of radiotherapy planning. The purpose was to investigate the changes in volume and motion of oesophageal cancer during radiotherapy using four-dimensional computed tomography (4D-CT). Methods and materials: In total, 109 enhanced 4D-CT data sets were acquired for 38 patients throughout treatment. Gross tumour volumes (GTVs) were outlined on each data set. Variations in volume, motion, and position were calculated for GTV and internal GTV (IGTV) during treatment. Results: GTV (25%, P < 0.01) and IGTV (27%, P < 0.01) had decreased significantly when measured at the twentieth fraction. Larger intrafractional GTV centre shifts (P < 0.01) were observed in the superior–inferior direction (median value of 3.1 mm) compared with the right–left and anterior–posterior directions (1.6 mm and 1.4 mm, respectively). The interfractional shift of the IGTV centre was not significant during radiotherapy. The overlap ratios of the targets decreased for both GTV and IGTV during treatment. Conclusions: Variations in GTV and IGTV centre shifts were not significant throughout treatment. However, tumour volume decreased significantly by the twentieth fraction. Finally, changes in oesophageal tumour volume and motion may decrease the overlap ratio for GTV and IGTV during radiotherapy

  12. Development of evaluation and performance verification technology for radiotherapy radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. Y.; Jang, S. Y.; Kim, B. H. and others

    2005-02-15

    No matter how much the importance is emphasized, the exact assessment of the absorbed doses administered to the patients to treat the various diseases such as lately soaring malignant tumors with the radiotherapy practices is the most important factor. In reality, several over-exposed patients from the radiotherapy practice become very serious social issues. Especially, the development of a technology to exactly assess the high doses and high energies (In general, dose administered to the patients with the radiotherapy practices are very huge doses, and they are about three times higher than the lethal doses) generated by the radiation generators and irradiation equipment is a competing issue to be promptly conducted. Over fifty medical centers in Korea operate the radiation generators and irradiation equipment for the radiotherapy practices. However, neither the legal and regulatory systems to implement a quality assurance program are sufficiently stipulated nor qualified personnel who could run a program to maintain the quality assurance and control of those generators and equipment for the radiotherapy practices in the medical facilities are sufficiently employed. To overcome the above deficiencies, a quality assurance program such as those developed in the technically advanced countries should be developed to exactly assess the doses administered to patients with the radiotherapy practices and develop the necessary procedures to maintain the continuing performance of the machine or equipment for the radiotherapy. The QA program and procedures should induce the fluent calibration of the machine or equipment with quality, and definitely establish the safety of patients in the radiotherapy practices. In this study, a methodology for the verification and evaluation of the radiotherapy doses is developed, and several accurate measurements, evaluations of the doses delivered to patients and verification of the performance of the therapy machine and equipment are

  13. Development of evaluation and performance verification technology for radiotherapy radiation

    International Nuclear Information System (INIS)

    No matter how much the importance is emphasized, the exact assessment of the absorbed doses administered to the patients to treat the various diseases such as lately soaring malignant tumors with the radiotherapy practices is the most important factor. In reality, several over-exposed patients from the radiotherapy practice become very serious social issues. Especially, the development of a technology to exactly assess the high doses and high energies (In general, dose administered to the patients with the radiotherapy practices are very huge doses, and they are about three times higher than the lethal doses) generated by the radiation generators and irradiation equipment is a competing issue to be promptly conducted. Over fifty medical centers in Korea operate the radiation generators and irradiation equipment for the radiotherapy practices. However, neither the legal and regulatory systems to implement a quality assurance program are sufficiently stipulated nor qualified personnel who could run a program to maintain the quality assurance and control of those generators and equipment for the radiotherapy practices in the medical facilities are sufficiently employed. To overcome the above deficiencies, a quality assurance program such as those developed in the technically advanced countries should be developed to exactly assess the doses administered to patients with the radiotherapy practices and develop the necessary procedures to maintain the continuing performance of the machine or equipment for the radiotherapy. The QA program and procedures should induce the fluent calibration of the machine or equipment with quality, and definitely establish the safety of patients in the radiotherapy practices. In this study, a methodology for the verification and evaluation of the radiotherapy doses is developed, and several accurate measurements, evaluations of the doses delivered to patients and verification of the performance of the therapy machine and equipment are

  14. Endorectal MRI assessment of local relapse after surgery for prostate cancer: A model to define treatment field guidelines for adjuvant radiotherapy in patients at high risk for local failure

    International Nuclear Information System (INIS)

    Purpose: To assess the role of endorectal magnetic resonance imaging (MRI) in defining local relapse after radical prostatectomy for prostate cancer to help to reassess the clinical target volume (CTV) for adjuvant postprostatectomy radiotherapy. Methods and Materials: Sixty patients undergoing an endorectal MRI before salvage radiotherapy were selected. Spatial coordinates of the relapses were assessed using two reference points: the inferior border of the pubic symphysis (point 1) and the urethro-vesical anastomosis (point 2). Every lesion on MRI was delineated on the planning computed tomography and center of mass coordinates were plotted in two separate diagrams (along the x, y, and z axes) with the urethro-vesical anastomosis as the coordinate origin. An 'ideal' CTV was constructed, centered at a point defined by the mathematical means of each of the three coordinates with dimensions defined as twice 2 standard deviations in each of the three axes. The dosimetric impact of the new CTV definition was evaluated in six adjuvantly treated patients. Results: The ideal CTV center of mass was located at coordinates 0 (x), -5 (y), and -3 (z) mm with SDs of 6 (x), 6 (y), and 9 (z) mm, respectively. The CTV size was 24 (x) x 24 (y) x 36 (z) mm. Significant rectal sparing was observed with the new CTV. Conclusions: A CTV with an approximately cylindrical shape (∼4 x 3 cm) centered 5 mm posterior and 3 mm inferior to the urethro-vesical anastomosis was defined. Such CTV may reduce the irradiation of normal nontarget tissue in the pelvis potentially improving treatment tolerance

  15. Assessment of nasopharyngeal carcinomas after radiotherapy with a hybrid camera-based PET/CT system using 18F-FDG

    International Nuclear Information System (INIS)

    Objective: To evaluate the clinical values of hybrid imaging using a gamma camera-based PET/CT system and 18F-FDG in detection of recurrent or persistent nasopharyngeal carcinomas after radiotherapy. Methods: Nineteen patients with nasopharyngeal carcinomas were evaluated three months after radiotherapy. The recurrent or metastasis lesions were suspected by routinely diagnostic X-ray CT examinations. Hybrid imaging was performed using a device combining low-dose CT and gamma camera-based PET system (GE Millennium VG with Hawkeye) to differentiate recurrent or residual tumors from benign lesions. The presence or absence of recurrent or metastasis lesions were confirmed by the histopathologic examinations and/or 3-12 month clinical follow-up. The sequence of x-ray transmission scan and coincidence detection was initiated 60 min after the injection of 158.4-314.5 MBq (4.28-8.5 mCi) 18F-FDG. The data are rebinned into 90 projections and reconstructed iteratively including attenuation correction. The resulting images were interpreted by at least three nuclear medicine physicians together. The radioactivity ratios of target to non-target (T/NT) were calculated. Results: In the 10 patients with proven recurrent or metastasis lesions, CT findings were probable in 3 patients and doubtful in 7 ones. 18F-FDG coincidence imaging were true positive and showed significantly increased FDG uptake in all the 10 patients (10/10). The lesions' T/NT were between 1.23-5.75 (3.25±1.07 mean±s.d.). In the 9 patients eliminated the tumor recurrence, CT findings were probable in 2 patients and doubtful in 7 patients. 18F-FDG coincidence imaging were tree negative in 8 patients (8/9). The lesions' T/NT were between 0.87-3.21 (1.25±0.49 mean±s.d.). Only 1 finding was false positive in the patient with infection in the pharyngeal back and neck lymph nodes. The lesions' T/NT was 3.21. No matter what the 18F-FDG coincidence imaging was positive or negative, the fusion image can more directly

  16. Serial assessment of FDG-PET FDG uptake and functional volume during radiotherapy (RT) in patients with non-small cell lung cancer (NSCLC)

    International Nuclear Information System (INIS)

    Objectives: The objectives were (i) to confirm that diagnostic FDG-PET images could be obtained during thoracic radiotherapy, (ii) to verify that significant changes in FDG uptake or volume could be measured early enough to adapt the radiotherapy plan and (iii) to determine an optimal time window during the radiotherapy course to acquire a single FDG-PET examination that would be representative of tumour response. Methods: Ten non-small cell lung carcinoma (NSCLC) patients with significant PET/CT-FDG tumour radioactivity uptake (versus the background level), candidates for curative radiotherapy (RT, n = 4; 60–70 Gy, 2 Gray per fraction, 5 fractions per week) or RT plus chemotherapy (CT-RT, n = 6), were prospectively evaluated. Using a Siemens Biograph, 5 or 6 PET/CT scans (PETn, n = 0–5) were performed for each patient. Each acquisition included a 15-min thoracic PET with respiratory gating (RG) 60 ± 5 min post-injection of the FDG (3.5 MBq/kg), followed by a standard, 5-min non-gated (STD) thoracic PET. PET0 was performed before the first RT fraction. During RT, PET1–5 were performed every 7 fractions, i.e., at 14 Gy total dose increment. FDG uptake was measured as the variation of SUVmax,PETn versus SUVmax,PET0. Each lesions’ volume was measured by (i) visual delineation by an experienced nuclear physician, (ii) 40% SUVmax fixed threshold and (iii) a semi-automatic adaptive threshold method. Results: A total of 53 FDG-PET scans were acquired. Seventeen lesions (6 tumours and 11 nodes) were visible on PET0 in the 10 patients. The lesions were located either in or near the mediastinum or in the apex, without significant respiratory displacements at visual inspection of the gated images. Healthy lung did not cause motion artefacts in the PET images. As measured on 89 lesions, both the absolute and relative SUVmax values decreased as the RT dose increased. A 50% SUVmax decrease was obtained around a total dose of 45 Gy. Out of the 89 lesions, 75 remained

  17. Four-dimensional characterization of inflow to and wakes from a multi-MW turbine: overview of the Turbine Wake and Inflow Characterization Study (TWICS2011)

    Science.gov (United States)

    Lundquist, J. K.; Banta, R. M.; Pichugina, Y.; Brewer, A.; Alvarez, R. J.; Sandberg, S. P.; Kelley, N. D.; Aitken, M.; Clifton, A.; Mirocha, J. D.

    2011-12-01

    To support substantial deployment of renewably-generated electricity from the wind, critical information about the variability of wind turbine wakes in the real atmosphere from multi-MW turbines is required. The assessment of the velocity deficit and turbulence associated with industrial-scale turbines is a major issue for wind farm design, particularly with respect to the optimization of the spacing between turbines. The significant velocity deficit and turbulence generated by upstream turbines can reduce the power production and produce harmful vibrations in downstream turbines, which can lead to excess maintenance costs. The complexity of wake effects depends on many factors arising from both hardware (turbine size, rotor speed, and blade geometry, etc.) and from meteorological considerations such as wind velocity, gradients of wind across the turbine rotor disk, atmospheric stability, and atmospheric turbulence. To characterize the relationships between the meteorological inflow and turbine wakes, a collaborative field campaign was designed and carried out at the Department of Energy's National Wind Technology Center (NREL/NWTC) in south Boulder, Colorado, in spring 2011. This site often experiences channeled flow with a consistent wind direction, enabling robust statistics of wake velocity deficits and turbulence enhancements. Using both in situ and remote sensing instrumentation, measurements upwind and downwind of multi-megawatt wind turbine in complex terrain quantified the variability of wind turbine inflow and wakes from an industrial-scale turbine. The turbine of interest has a rated power of 2.3 MW, a rotor diameter of 100m, and a hub height of 80m. In addition to several meteorological towers, one extending to hub height (80m) and another extending above the top of the rotor disk (135m), a Triton mini-sodar and a Windcube lidar characterized the inflow to the turbine and the variability across the site. The centerpiece instrument of the TWICS campaign

  18. CMTO Four-dimensional Analysis Method of Competitive Intelligence and Its Application%竞争情报分析的CMTO四维分析法及其应用

    Institute of Scientific and Technical Information of China (English)

    苗红; 宋昱晓; 黄鲁成; 娄岩; 王晓宇

    2015-01-01

    Competitive intelligence analysis method is the key way to acquire the most accurate competitive intelligence It is also the basis of competitive intelligence application to be realized. This paper proposes a"Capability-Market-Time-Opportunity" four-dimensional a-nalysis method ( hereinafter referred to as CMTO four-dimensional analysis method) , which offsets the deficiency of the CMT three-di-mensional analysis for lack of direction caused by negligence of competitive opportunities analysis . And this method augments the amount of information in competitive intelligence analysis. This paper carries out empirical study on the application of CMTO four-dimensional a-nalysis method by taking wearable technology. For example,this method verifies the feasibility and superiority of CMTO. Research results show that the following fields are more competitive in the future:carrier and material, measurement, battery and circuit, etc. CMTO can help enterprises by providing fairly comprehensive, valuable intelligence information.%竞争情报分析方法是获取竞争情报最精准、最有价值的关键途径,也是竞争情报应用得以实现的基础。提出一种“市场-能力-时间-机会”四维分析方法(简称CMTO四维分析法),弥补了CMT三维分析法未考虑分析竞争机会而缺乏方向性的不足,增加了竞争情报分析的信息量。并用可穿戴技术验证了该方法的可行性及优越性。研究表明未来竞争机会较大的技术领域集中在载体和材料、测量、电池和电路装置等,为辅助企业决策提供了较为全面而有价值的情报信息。

  19. Long-term outcome and toxicity of hypofractionated stereotactic body radiotherapy as a boost treatment for head and neck cancer: the importance of boost volume assessment

    Directory of Open Access Journals (Sweden)

    Lee Dong

    2012-06-01

    Full Text Available Abstract Background The aim of this study was to report the long-term clinical outcomes of patients who received stereotactic body radiotherapy (SBRT as a boost treatment for head and neck cancer. Materials and methods Between March 2004 and July 2007, 26 patients with locally advanced, medically inoperable head and neck cancer or gross residual tumors in close proximity to critical structures following head and neck surgery were treated with SBRT as a boost treatment. All patients were initially treated with standard external beam radiotherapy (EBRT. SBRT boost was prescribed to the median 80% isodose line with a median dose of 21 (range 10–25 Gy in 2–5 (median, 5 fractions. Results The median follow-up after SBRT was 56 (range 27.6 − 80.2 months. The distribution of treatment sites in 26 patients was as follows: the nasopharynx, including the base of the skull in 10 (38.5%; nasal cavity or paranasal sinus in 8 (30.8%; periorbit in 4 (15.4%; tongue in 3 (11.5%; and oropharyngeal wall in 1 (3.8%. The median EBRT dose before SBRT was 50.4 Gy (range 39.6 − 70.2. The major response rate was 100% with 21 (80.8% complete responses (CR. Severe (grade ≥ 3 late toxicities developed in 9 (34.6% patients, and SBRT boost volume was a significant parameter predicting severe late complication. Conclusions The present study demonstrates that a modern SBRT boost is a highly efficient tool for local tumor control. However, we observed a high frequency of serious late complications. More optimized dose fractionation schedule and patient selection are required to achieve excellent local control without significant late morbidities in head and neck boost treatment.

  20. Assessment of the risk factors for impending fractures following radiotherapy for long bone metastases using CT scan-based virtual simulation: a retrospective study

    International Nuclear Information System (INIS)

    Radiotherapy for long bone metastases (RTLB) can be complicated by fractures, which considerably increase morbidity and mortality. The aim of this study was to analyze the risk factors for impending fractures following radiotherapy for long bone metastases (RTLB) using CT scan-based virtual simulation. Forty-seven (47) patients were treated with RTLB (18 lung, 11 breast, 10 prostate and 8 other cancers) for a period of 18 months. Two doctors analyzed the CT images prior to radiation therapy. The impending fractures were then monitored and the correlation between bone scan parameters and fracture occurrence was analyzed. The male gender ratio was 0.57 and the mean age 62.8 (33–93) years. The average size of the metastatic lesions was 32 (8–87) x 2 (6–81) x 52 (7–408) mm with cortical involvement (CI) in 66% of cases. The site was in the upper third of the bone in 92% of cases (28 femoral, 17 humeral and two tibial). Ten fractures occurred: two during RTLB, seven after one month and one after 6.6 months. The fractured lesions measured 48 (17–87) x 34 (12–66) x 76 (38–408) mm. The predictive parameters for fracture were osteolytic (39% vs. 10%; p = 0.02) and permeative lesions (42% vs. 0%; p < 0.0005), a Mirels score ≥9 (42% vs. 0%; p < 0.0005), circumferential CI ≥30% (71% vs. 0%, p < 0.00001), CI ≥45 mm in height (67% vs. 0%, p < 0.00001) and CI in thickness =100% (40% vs. 0%; p = 0.0008). In the multivariate analysis, circumferential CI ≥30% was the only predictive parameter for fracture (p = 0.00035; OR = 62; CI 95%: 6.5-595). Overall survival was 91% and 40% at one month and twelve months respectively. Prophylactic primary fixation surgery should always be considered when the circumferential CI ≥30%

  1. Normal tissue response to low doses of radiotherapy assessed by molecular markers - A study of skin in patients treated for prostate cancer

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate normal tissue response by molecular markers to multi fraction low doses of ionizing radiation, with the focus on changes in repopulation, estimated using Ki-67 as the proliferation marker, and on expressions of the p53 and p21 proteins, identified as key proteins in the DNA damage checkpoint. Repeated skin biopsies were taken from patients treated for prostate cancer with radiotherapy. The expressions of Ki-67, p53 and p21 of the keratinocytes in the basal cell layer of the epidermis were quantified immunohistochemically. The dose to the basal layer was 1.1 Gy per fraction, given five times per week for seven weeks. The indices of the three markers were determined over the whole period. A significant suppression of the Ki-67 index was observed during the first weeks, followed by a significant gradual increase in the Ki-67 index over the last weeks. The p53 and p21 protein levels were almost zero in the unirradiated skin. Upon irradiation, both the p53 and p21 index increased in a pattern very congruent to the Ki-67 index. In conclusion, daily fractions of about 1 Gy to the skin resulted in, for the keratinocytes in the basal layer, a cell growth arrest for a couple of weeks and a subsequent acceleration in repopulation during the following weeks of irradiation. The present findings also provided novel insights into the role of the p53/p21 pathway in the response of a normal epithelium to ionizing radiation as it is applied in radiotherapy

  2. Radiotherapy in the management of Graves` ophthalmopathy

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, Koh-ichi; Hareyama, Masato; Oouchi, Atsushi; Shidou, Mitsuo; Nagakura, Hisayasu; Morita, Kazuo; Osanai, Hajime; Ohtsuka, Kenji; Hinoda, Yuji [Sapporo Medical Univ. (Japan). School of Medicine

    1998-06-01

    To report the results of radiotherapy for patients with failure, adverse reactions or relative contraindications to the use of steroids or immunosuppressants, by using newly developed quantitative indexes. Fourteen female and six male patients with Graves` ophthalmopathy were treated with radiotherapy between 1989 and 1996. Prior to radiotherapy, eight patients received treatment with prednisone, four received immunosuppressants and four received a combination of both. Four patients with contraindications to steroids were initially managed with radiotherapy. Most of the patients received a dose of 24-28 Gy in 2 Gy fractions. We used the newly developed motility limitation index to assess extraocular motility. Treatment was well tolerated. There have been no late complications. All 12 patients with soft tissue signs such as edema, irritation, tearing and pain were improved. Proptosis did not improve or improved only slightly, 3 mm at best. However, proptosis in all but two has been stabilized and has not deteriorated in the follow-up period. Most of the patients have experienced an improvement of eye-muscle motility. Extraocular muscles that work for elevation were impaired more severely than the other muscles and this tended to remain. Of the 16 patients using steroids before or when radiotherapy was initiated, 15 were tapered off and only one patient required additional steroids, thus sparing the majority from steroid adverse reactions. Radiotherapy was effective in preventing exacerbations of active inflammatory ophthalmopathy in patients with Graves` disease with minimal morbidity and thus eliminated the adverse reactions associated with protracted corticosteroid use. The newly developed motility limitation index was useful in detecting delicate changes in motility of individual extraocular muscles. (author)

  3. Radiotherapy Breast Boost With Reduced Whole-Breast Dose Is Associated With Improved Cosmesis: The Results of a Comprehensive Assessment From the St. George and Wollongong Randomized Breast Boost Trial

    Energy Technology Data Exchange (ETDEWEB)

    Hau, Eric, E-mail: helloerico@yahoo.com [Cancer Care Centre, St. George Hospital, Kogarah, Sydney (Australia); Browne, Lois H.; Khanna, Sam; Cail, Stacy; Cert, Grad; Chin, Yaw; Clark, Catherine; Inder, Stephanie; Szwajcer, Alison; Graham, Peter H. [Cancer Care Centre, St. George Hospital, Kogarah, Sydney (Australia)

    2012-02-01

    Purpose: To evaluate comprehensively the effect of a radiotherapy boost on breast cosmetic outcomes after 5 years in patients treated with breast-conserving surgery. Methods: The St. George and Wollongong trial (NCT00138814) randomized 688 patients with histologically proven Tis-2, N 0-1, M0 carcinoma to the control arm of 50 Gy in 25 fractions (342 patients) and the boost arm of 45 Gy in 25 fractions to the whole breast followed by a 16 Gy in 8 fraction electron boost (346 patients). Five-year cosmetic outcomes were assessed by a panel subjectively in 385 patients and objectively using pBRA (relative breast retraction assessment). A subset of patients also had absolute BRA measurements. Clinician assessment and patient self-assessment of overall cosmetic and specific items as well as computer BCCT.core analysis were also performed. Results: The boost arm had improved cosmetic overall outcomes as scored by the panel and BCCT.core software with 79% (p = 0.016) and 81% (p = 0.004) excellent/good cosmesis respectively compared with 68% in no-boost arm. The boost arm also had lower pBRA and BRA values with a mean difference of 0.60 and 1.82 mm, respectively, but was not statistically significant. There was a very high proportion of overall excellent/good cosmetic outcome in 95% and 93% in the boost and no-boost arms using patient self-assessment. However, no difference in overall and specific items scored by clinician assessment and patient self-assessment was found. Conclusion: The results show the negative cosmetic effect of a 16-Gy boost is offset by a lower whole-breast dose of 45 Gy.

  4. Radiotherapy Breast Boost With Reduced Whole-Breast Dose Is Associated With Improved Cosmesis: The Results of a Comprehensive Assessment From the St. George and Wollongong Randomized Breast Boost Trial

    International Nuclear Information System (INIS)

    Purpose: To evaluate comprehensively the effect of a radiotherapy boost on breast cosmetic outcomes after 5 years in patients treated with breast-conserving surgery. Methods: The St. George and Wollongong trial (NCT00138814) randomized 688 patients with histologically proven Tis-2, N 0–1, M0 carcinoma to the control arm of 50 Gy in 25 fractions (342 patients) and the boost arm of 45 Gy in 25 fractions to the whole breast followed by a 16 Gy in 8 fraction electron boost (346 patients). Five-year cosmetic outcomes were assessed by a panel subjectively in 385 patients and objectively using pBRA (relative breast retraction assessment). A subset of patients also had absolute BRA measurements. Clinician assessment and patient self-assessment of overall cosmetic and specific items as well as computer BCCT.core analysis were also performed. Results: The boost arm had improved cosmetic overall outcomes as scored by the panel and BCCT.core software with 79% (p = 0.016) and 81% (p = 0.004) excellent/good cosmesis respectively compared with 68% in no-boost arm. The boost arm also had lower pBRA and BRA values with a mean difference of 0.60 and 1.82 mm, respectively, but was not statistically significant. There was a very high proportion of overall excellent/good cosmetic outcome in 95% and 93% in the boost and no–boost arms using patient self-assessment. However, no difference in overall and specific items scored by clinician assessment and patient self-assessment was found. Conclusion: The results show the negative cosmetic effect of a 16-Gy boost is offset by a lower whole-breast dose of 45 Gy.

  5. 四维彩超在胎儿先天性畸形中的临床诊断价值%Four-dimensional color Doppler ultrasound in examination in prenatal screening of fetal malformation

    Institute of Scientific and Technical Information of China (English)

    罗妙云

    2014-01-01

    目的 探讨四维彩超在胎儿先天性畸形中的诊断价值.方法 随机观察我院2012年1月至2014年1月孕中晚期孕妇1200例产前常规超声检查结果,所有孕妇均进行了二维超声和四维超声检查,并随访至产后1个月,比较二维超声和四维超声诊断胎儿先天性畸形的准确性.结果 经产后临床证实,共发现先天性胎儿畸形34例,其中神经管畸形10例,心脏畸形8例,唇腭裂7例,泌尿系畸形3例,四肢畸形3例,腹部畸形1例,其他2例.四维超声检出畸形31例,与产后符合率91.17%;漏诊3例,其中多指畸形1例,脊柱裂2例.二维超声检出畸形26例,符合率76.47%;漏诊8例,其中唇腭裂2例,多指畸形2例,脊柱裂3例,足内翻1例.二维和四维超声的诊断符合率比较差异具有统计学意义(P<0.05).结论 四维超声更能多方位、多切面观察胎儿宫内发育情况,对诊断胎儿体表畸形具有更直观和准确的判断,具有较高的临床价值.%Objective To investigate the diagnostic value of four-dimensional (4D) color Doppler ultrasound examination in prenatal screening of fetal malformation.Methods 1200 pregnant women were observed and detected by four-dimensional color Doppler and two dimensional ultrasound.The results were compared with the results confirmed by clinical pathology.Results 34 cases were detected with congenital defects; among which,10 got defects in nervous system,8 heart deformity,7 cheilopalatognathus,3 urinary tract malformation,3 limb deformity,1 abdominal deformity,and the other 2 cases.31 cases were detected with deformity by four-dimensional color Doppler,with a postpartum coincidence rate of 91.17%; and 3 cases were misdiagnosed,of which 1 case had polydactyly deformity and 2 cases spina bifida.26 cases were detected with deformity by two-dimensional ultrasony,with a postpartum coincidence rate of 76.47%; and 8 cases were misdiagnosed,of which 2 cases had cleft lip and palate,2 case polydactyly

  6. Dynamics of tumor hypoxia assessed by 18F-FAZA PET/CT in head and neck and lung cancer patients during chemoradiation: Possible implications for radiotherapy treatment planning strategies

    International Nuclear Information System (INIS)

    Introduction: To define the optimal time point for the integration of hypoxia 18F-FAZA-PET/CT information into radiotherapy treatment planning to benefit from hypoxia modification or dose escalation treatment. Therefore, we performed a prospective cohort study, using serial hypoxic imaging (18F-FAZA-PET/CT) prior to and at several time-points during (chemo)radiotherapy (CHRT) in six head and neck squamous cell (HNSCC) and six non-small cell lung cancer (NSCLC) patients. Methods: The spatio-temporal dynamics of tumor hypoxia and fractional hypoxic volumes (FHV) were evaluated using a voxel-by-voxel analysis based on a 18F-FAZA-T/B ratio of 1.4 at four time points in HNSCC patients, at baseline (FAZA-BL), at week one (FAZA-W1), two (FAZA-W2), and four (FAZA-W4) during CHRT and at three time points in NSCLC patients (baseline; W2, W4). Results: Ten out of twelve patients showed a substantial pre-treatment tumor hypoxia representing a FHV ⩾ 1.4 assessed by 18F-FAZA-PET/CT. The median FHV was 38% (FAZA-BL), 15% (FAZA-W1), 17% (FAZA-W2) and 1.5% (FAZA-W4) in HNSCC patients, and 34% (FAZA-BL), 26% (FAZA-W2) and 26% (FAZA-W4) in NSCLC patients, respectively. Stable tumor hypoxia was observed in three HNSCC patients and two NSCLC patients at FAZA-W2. In three HNSCC patients and two NSCLC patients FHVs declined to non-detectable hypoxia levels at FAZA-W4 during CHRT, while two NSCLC patients, showed increasing FHVs. Conclusion: Our results indicate that, instead of using the FAZA-BL scan as the basis for the dose escalation, FAZA-W2 of CHRT is most suitable and might provide a more reliable basis for the integration of 18F-FAZA-PET/CT information into radiotherapy treatment planning for hypoxia-directed dose escalation strategies

  7. Chemical modifiers of radiotherapy

    International Nuclear Information System (INIS)

    Only two groups, anticancer drugs and radiosensitizers are discussed among many groups of chemical modifiers. In combined radiotherapy (RT) with chemotherapy (CT), sequential administration seems to be superior to concomitant administration, because simultaneous use enhances intensively normal tissue damage. In sequential administration, interruption of CT during RT causes growth of distant metastases. So, alternating scheme of RT and CT is proposed and evaluated clinically. Hypoxic cell sensitizers including well-known misonidazole and PLDR inhibitors (Ara-A etc.) are promising in radiotherapy. They should be used intermittently two or three times during RT in order to avoid neurotoxicity of misonidazole. (author) 70 refs

  8. Xerostomia induced by radiotherapy

    Directory of Open Access Journals (Sweden)

    Alimi D

    2015-08-01

    Full Text Available David Alimi Department of Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, PA, USAWe read with great interest the excellent review on xerostomia induced by radiotherapy, by Pinna et al.1 The authors should be congratulated for a very detailed review of the physiopathology, clinical symptoms, and therapeutic management of an extremely difficult condition. Although we agree that the use of anticholinergic medication represents treatment, it requires the patient to have residual salivary gland function. Unfortunately, it is well established that in most cases radiotherapy destroys most of the salivary gland and associated salivary secretions.     

  9. Using Fluorodeoxyglucose Positron Emission Tomography to Assess Tumor Volume During Radiotherapy for Non-Small-Cell Lung Cancer and Its Potential Impact on Adaptive Dose Escalation and Normal Tissue Sparing

    International Nuclear Information System (INIS)

    Purpose: To quantify changes in fluorodeoxyglucose (FDG)-avid tumor volume on positron emission tomography/computed tomography (PET/CT) during the course of radiation therapy and examine its potential use in adaptive radiotherapy for tumor dose escalation or normal tissue sparing in patients with non-small-cell lung cancer (NSCLC). Methods and Materials: As part of a pilot study, patients with Stage I-III NSCLC underwent FDG-PET/CT before radiotherapy (RT) and in mid-RT (after 40-50 Gy). Gross tumor volumes were contoured on CT and PET scans obtained before and during RT. Three-dimensional conformal RT plans were generated for each patient, first using only pretreatment CT scans. Mid-RT PET volumes were then used to design boost fields. Results: Fourteen patients with FDG-avid tumors were assessed. Two patients had a complete metabolic response, and 2 patients had slightly increased FDG uptake in the adjacent lung tissue. Mid-RT PET scans were useful in the 10 remaining patients. Mean decreases in CT and PET tumor volumes were 26% (range, +15% to -75%) and 44% (range, +10% to -100%), respectively. Designing boosts based on mid-RT PET allowed for a meaningful dose escalation of 30-102 Gy (mean, 58 Gy) or a reduction in normal tissue complication probability (NTCP) of 0.4-3% (mean, 2%) in 5 of 6 patients with smaller yet residual tumor volumes. Conclusions: Tumor metabolic activity and volume can change significantly after 40-50 Gy of RT. Using mid-RT PET volumes, tumor dose can be significantly escalated or NTCP reduced. Clinical studies evaluating patient outcome after PET-based adaptive RT are ongoing

  10. Advances of Precise Radiotherapy for Lung Cancer

    Directory of Open Access Journals (Sweden)

    Xin WANG

    2011-11-01

    Full Text Available At present lung tumor radiation therapy has entered the accurate radiotherapy era. Precise radiotherapy includes intensity modulated radiotherapy (IMRT, image-guided radiotherapy (IGRT and stereotactic body radiotherapy (SBRT. During the process of implementing precise radiotherapy, these problems should be fully considered to ensure executing precise radiotherapy accurately: patient positioning, controlling of the lung tumor motion, selecting of image techniques, PTV margin, dose prescription and reporting, arrangement of beams, controlling of dose volume and treatment delivering.

  11. Randomised trial of standard 2D radiotherapy (RT) versus intensity modulated radiotherapy (IMRT) in patients prescribed breast radiotherapy

    International Nuclear Information System (INIS)

    Background: Radiation dose distributions created by two dimensional (2D) treatment planning are responsible for partial volumes receiving >107% of the prescribed dose in a proportion of patients prescribed whole breast radiotherapy after tumour excision of early breast cancer. These may contribute to clinically significant late radiation adverse effects. Aim: To test three dimensional (3D) intensity modulated radiotherapy (IMRT) against 2D dosimetry using standard wedge compensators in terms of late adverse effects after whole breast radiotherapy. Methods: Three hundred and six women prescribed whole breast radiotherapy after tumour excision for early stage cancer were randomised to 3D IMRT (test arm) or 2D radiotherapy delivered using standard wedge compensators (control arm). All patients were treated with 6 or 10 MV photons to a dose of 50 Gy in 25 fractions to 100% in 5 weeks followed by an electron boost to the tumour bed of 11.1 Gy in 5 fractions to 100%. The primary endpoint was change in breast appearance scored from serial photographs taken before radiotherapy and at 1, 2 and 5 years follow up. Secondary endpoints included patient self-assessments of breast discomfort, breast hardness, quality of life and physician assessments of breast induration. Analysis was by intention to treat. Results: 240 (79%) patients with 5-year photographs were available for analysis. Change in breast appearance was identified in 71/122 (58%) allocated standard 2D treatment compared to only 47/118 (40%) patients allocated 3D IMRT. The control arm patients were 1.7 times more likely to have a change in breast appearance than the IMRT arm patients after adjustment for year of photographic assessment (95% confidence interval 1.2-2.5, p = 0.008). Significantly fewer patients in the 3D IMRT group developed palpable induration assessed clinically in the centre of the breast, pectoral fold, infra-mammary fold and at the boost site. No significant differences between treatment groups

  12. Dynamic MRI Analysis of Tumor and Organ Motion During Rest and Deglutition and Margin Assessment for Radiotherapy of Head-and-Neck Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, Julie A.; Paulson, Eric S.; Ahunbay, Ergun; Schultz, Christopher; Li, X. Allen [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States); Wang Dian, E-mail: dwang@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States)

    2011-12-01

    Purpose: To quantify swallowing frequency and tumor and normal structure displacements during deglutition using dynamic magnetic resonance imaging (MRI) and to determine planning target volume (PTV) margins to account for resting and deglutition-induced displacements in patients with head-and-neck cancer (HNC). Methods and Materials: Twenty-two patients with HNC were imaged in the treatment position using dynamic MRI. Sagittal images were acquired. Two-dimensional displacement was analyzed using contours of normal structures and GTV drawn for one swallowing event. Deglutition-induced displacements were quantified based on position change during deglutition relative to preswallow structure location for anterior (A), posterior (P), superior (S), and inferior (I) directions. Additional long-time MRI series were obtained from a subset of 11 patients while they were resting in order to determine swallowing frequency and duration. PTV margins to account for setup error, frequency and duration of deglutition, and resting and deglutition-induced GTV motion were calculated. Results: Mean maximum resting displacements ranged from 1.5 to 3.1 mm for combined GTV subsites. Mean maximum swallowing GTV displacement for combined subsites ranged from 4.0 to 11.6 mm. Swallowing was nonperiodic, with a frequency ranging from 0 to 19 swallows over 12.8 min and mean swallow duration of 3.5 s. Based on the average swallowing characteristics in this cohort, the average PTV margins to account for setup error and tumor motion are estimated to be 4.7 mm anteriorly, 4.2 mm posteriorly, 4.7 mm inferiorly, and 6.0 mm superiorly. Conclusions: The measurable mean maximum resting displacement for the GTV indicates that tumor motion occurs even when the patient is not swallowing. Nonuniform margins should be used as a standard PTV margin that accounts for setup error and tumor motion in radiotherapy of HNC unless adaptive radiotherapy with respect to intrafraction tumor motion is performed. The

  13. Dynamic MRI Analysis of Tumor and Organ Motion During Rest and Deglutition and Margin Assessment for Radiotherapy of Head-and-Neck Cancer

    International Nuclear Information System (INIS)

    Purpose: To quantify swallowing frequency and tumor and normal structure displacements during deglutition using dynamic magnetic resonance imaging (MRI) and to determine planning target volume (PTV) margins to account for resting and deglutition-induced displacements in patients with head-and-neck cancer (HNC). Methods and Materials: Twenty-two patients with HNC were imaged in the treatment position using dynamic MRI. Sagittal images were acquired. Two-dimensional displacement was analyzed using contours of normal structures and GTV drawn for one swallowing event. Deglutition-induced displacements were quantified based on position change during deglutition relative to preswallow structure location for anterior (A), posterior (P), superior (S), and inferior (I) directions. Additional long-time MRI series were obtained from a subset of 11 patients while they were resting in order to determine swallowing frequency and duration. PTV margins to account for setup error, frequency and duration of deglutition, and resting and deglutition-induced GTV motion were calculated. Results: Mean maximum resting displacements ranged from 1.5 to 3.1 mm for combined GTV subsites. Mean maximum swallowing GTV displacement for combined subsites ranged from 4.0 to 11.6 mm. Swallowing was nonperiodic, with a frequency ranging from 0 to 19 swallows over 12.8 min and mean swallow duration of 3.5 s. Based on the average swallowing characteristics in this cohort, the average PTV margins to account for setup error and tumor motion are estimated to be 4.7 mm anteriorly, 4.2 mm posteriorly, 4.7 mm inferiorly, and 6.0 mm superiorly. Conclusions: The measurable mean maximum resting displacement for the GTV indicates that tumor motion occurs even when the patient is not swallowing. Nonuniform margins should be used as a standard PTV margin that accounts for setup error and tumor motion in radiotherapy of HNC unless adaptive radiotherapy with respect to intrafraction tumor motion is performed. The

  14. Erythropoietin and radiotherapy; Erythropoietine et radiotherapie

    Energy Technology Data Exchange (ETDEWEB)

    Le Fur, E.; Albarghach, M.N.; Pradier, O. [CHU de Morvan, Dept. de radiotherapie, 29 - Brest (France)

    2010-01-15

    Erythropoietin (E.P.O.) is a glycoprotein hormone. This hormone is a growth factor for red blood cells precursors in the bone marrow. The decrease of oxygen partial pressure, a reduced number of erythrocytes caused by bleeding or excessive destruction, or increased tissues oxygen requirements lead to increased secretion of E.P.O.. Its action takes place on bone marrow erythroblastic cells through specific receptors. E.P.O. stimulates the proliferation of red cell precursors stem cells in the bone marrow, thus increasing their production in one to two weeks. The effectiveness of E.P.O. at increasing haemoglobin and improving patients quality of life has been demonstrated by several studies. However, its use in radiotherapy remains controversial. While tumour hypoxia caused by anaemia is a factor of radio resistance and thus a source of local failure, tumour expression of E.P.O. receptors presents a significant risk for tumour progression and neo-angiogenesis, which would be increased during the administration of E.P.O.. The purpose of this article is to answer the question: is there a place for E.P.O. in combination with radiotherapy in the management of cancer?

  15. Adjuvant radiotherapy for gallbladder cancer: A dosimetric comparison of conformal radiotherapy and intensity-modulated radiotherapy

    Institute of Scientific and Technical Information of China (English)

    Xiao-Nan Sun; Qi Wang; Ben-Xing Gu; Yan-Hong Zhu; Jian-Bin Hu; Guo-Zhi Shi; Shu Zheng

    2011-01-01

    AIM: To assess the efficacy and toxicity of conformal radiotherapy (CRT) and compare with intensity-modulated radiotherapy (IMRT) in the treatment of gallbladder cancer.METHODS: Between November 2003 and January 2010, 20 patients with gallbladder cancer were treated with CRT with or without chemotherapy after surgical resection. Preliminary survival data were collected and examined using both Kaplan-Meier and actuarial analysis. Demographic and treatment parameters were collected. All patients were planned to receive 46-56 Gy in 1.8 or 2.0 Gy per fraction. CRT planning was compared with IMRT.RESULTS: The most common reported acute toxicities requiring medication (Radiation Therapy Oncology Group, Radiation Therapy Oncology Group Grade2) were nausea (10/20 patients) and diarrhea (3/20).There were no treatment-related deaths. Compared with CRT planning, IMRT significantly reduced the volume of right kidney receiving > 20 Gy and the volume of liver receiving > 30 Gy. IMRT has a negligible impact on the volume of left kidney receiving > 20 Gy. The 95% of prescribed dose for a planning tumor volume using either 3D CRT or IMRT planning were 84.0% ±6.7%, 82.9% ± 6.1%, respectively (P > 0.05).CONCLUSION: IMRT achieves similar excellent target coverage as compared with CRT planning, while reducingthe mean liver dose and volume above threshold dose. IMRT offers better sparing of the right kidney compared with CRT planning, with a significantly lower mean dose and volume above threshold dose.

  16. Triality of Four Dimensional Strings and Networks

    Internatio