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Sample records for four-dimensional radiotherapy planning

  1. A novel four-dimensional radiotherapy planning strategy from a tumor-tracking beam's eye view

    Science.gov (United States)

    Li, Guang; Cohen, Patrice; Xie, Huchen; Low, Daniel; Li, Diana; Rimner, Andreas

    2012-11-01

    To investigate the feasibility of four-dimensional radiotherapy (4DRT) planning from a tumor-tracking beam's eye view (ttBEV) with reliable gross tumor volume (GTV) delineation, realistic normal tissue representation, high planning accuracy and low clinical workload, we propose and validate a novel 4D conformal planning strategy based on a synthesized 3.5D computed tomographic (3.5DCT) image with a motion-compensated tumor. To recreate patient anatomy from a ttBEV in the moving tumor coordinate system for 4DRT planning (or 4D planning), the centers of delineated GTVs in all phase CT images of 4DCT were aligned, and then the aligned CTs were averaged to produce a new 3.5DCT image. This GTV-motion-compensated CT contains a motionless target (with motion artifacts minimized) and motion-blurred normal tissues (with a realistic temporal density average). Semi-automatic threshold-based segmentation of the tumor, lung and body was applied, while manual delineation was used for other organs at risk (OARs). To validate this 3.5DCT-based 4D planning strategy, five patients with peripheral lung lesions of small size (tumor and a minor beam aperture and weighting adjustment to maintain plan conformality. The dose-volume histogram (DVH) of the 4DCT plan was created with two methods: one is an integrated DVH (iDVH4D), which is defined as the temporal average of all 3D-phase-plan DVHs, and the other (DVH4D) is based on the dose distribution in a reference phase CT image by dose warping from all phase plans using the displacement vector field (DVF) from a free-form deformable image registration (DIR). The DVH3.5D (for the 3.5DCT plan) was compared with both iDVH4D and DVH4D. To quantify the DVH difference between the 3.5DCT plan and the 4DCT plan, two methods were used: relative difference (%) of the areas underneath the DVH curves and the volumes receiving more than 20% (V20) and 50% (V50) of prescribed dose of these 4D plans. The volume of the delineated GTV from different phase

  2. Four-dimensional treatment planning and fluoroscopic real-time tumor tracking radiotherapy for moving tumor

    International Nuclear Information System (INIS)

    Shirato, Hiroki; Shimizu, Shinichi; Kitamura, Kei; Nishioka, Takeshi; Kagei, Kenji; Hashimoto, Seiko; Aoyama, Hidefumi; Kunieda, Tatsuya; Shinohara, Nobuo; Dosaka-Akita, Hirotoshi; Miyasaka, Kazuo

    2000-01-01

    Purpose: To achieve precise three-dimensional (3D) conformal radiotherapy for mobile tumors, a new radiotherapy system and its treatment planning system were developed and used for clinical practice. Methods and Materials: We developed a linear accelerator synchronized with a fluoroscopic real-time tumor tracking system by which 3D coordinates of a 2.0-mm gold marker in the tumor can be determined every 0.03 second. The 3D relationships between the marker and the tumor at different respiratory phases are evaluated using CT image at each respiratory phase, whereby the optimum phase can be selected to synchronize with irradiation (4D treatment planning). The linac is triggered to irradiate the tumor only when the marker is located within the region of the planned coordinates relative to the isocenter. Results: The coordinates of the marker were detected with an accuracy of ± 1 mm during radiotherapy in the phantom experiment. The time delay between recognition of the marker position and the start or stop of megavoltage X-ray irradiation was 0.03 second. Fourteen patients with various tumors were treated by conformal radiotherapy with a 'tight' planning target volume (PTV) margin. They were surviving without relapse or complications with a median follow-up of 6 months. Conclusion: Fluoroscopic real-time tumor tracking radiotherapy following 4D treatment planning was developed and shown to be feasible to improve the accuracy of the radiotherapy for mobile tumors

  3. Mid-ventilation CT scan construction from four-dimensional respiration-correlated CT scans for radiotherapy planning of lung cancer patients

    NARCIS (Netherlands)

    Wolthaus, Jochem W. H.; Schneider, Christoph; Sonke, Jan-Jakob; van Herk, Marcel; Belderbos, José S. A.; Rossi, Maddalena M. G.; Lebesque, Joos V.; Damen, Eugène M. F.

    2006-01-01

    PURPOSE: Four-dimensional (4D) respiration-correlated imaging techniques can be used to obtain (respiration) artifact-free computed tomography (CT) images of the thorax. Current radiotherapy planning systems, however, do not accommodate 4D-CT data. The purpose of this study was to develop a simple,

  4. 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)

    Weiss, Elisabeth; Wijesooriya, Krishni; Ramakrishnan, Viswanathan; Keall, Paul J.

    2008-01-01

    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, D 2% and D 98% 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Hoon Jung, Sang; Min Yoon, Sang; Ho Park, Sung; Cho, Byungchul; Won Park, Jae; Jung, Jinhong; Park, Jin-hong; Hoon Kim, Jong; Do Ahn, Seung [Departments of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 138-736 (Korea, Republic of)

    2013-01-15

    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 D{sub mean} 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 D{sub max} and gEUD for stomach was decreased by 5.3%{+-} 5.8% (p= 0.003) and 9.7%{+-} 8.7% (p= 0.003), respectively. The D{sub max} 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, D{sub max} 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.

  6. Feasibility of four-dimensional conformal planning for robotic radiosurgery

    International Nuclear Information System (INIS)

    Schlaefer, A.; Fisseler, J.; Dieterich, S.; Shiomi, H.; Cleary, K.; Schweikard, A.

    2005-01-01

    Organ motion can have a severe impact on the dose delivered by radiation therapy, and different procedures have been developed to address its effects. Conventional techniques include breath hold methods and gating. A different approach is the compensation for target motion by moving the treatment beams synchronously. Practical results have been reported for robot based radiosurgery, where a linear accelerator mounted on a robotic arm delivers the dose. However, not all organs move in the same way, which results in a relative motion of the beams with respect to the body and the tissues in the proximity of the tumor. This relative motion can severely effect the dose delivered to critical structures. We propose a method to incorporate motion in the treatment planning for robotic radiosurgery to avoid potential overdosing of organs surrounding the target. The method takes into account the motion of all considered volumes, which is discretized for dose calculations. Similarly, the beam motion is taken into account and the aggregated dose coefficient over all discrete steps is used for planning. We simulated the treatment of a moving target with three different planning methods. First, we computed beam weights based on a 3D planning situation and simulated treatment with organ motion and the beams moving synchronously to the target. Second, beam weights were computed by the 4D planning method incorporating the organ and beam motion and treatment was simulated for beams moving synchronously to the target. Third, the beam weights were determined by the 4D planning method with the beams fixed during planning and simulation. For comparison we also give results for the 3D treatment plan if there was no organ motion and when the plan is delivered by fixed beams in the presence of organ motion. The results indicate that the new 4D method is preferable and can further improve the overall conformality of motion compensated robotic radiosurgery

  7. Outcome of four-dimensional stereotactic radiotherapy for centrally located lung tumors

    International Nuclear Information System (INIS)

    Nuyttens, Joost J.; Voort van Zyp, Noelle C. van der; Praag, John; Aluwini, Shafak; Klaveren, Rob J. van; Verhoef, Cornelis; Pattynama, Peter M.; Hoogeman, Mischa S.

    2012-01-01

    Purpose: To assess local control, overall survival, and toxicity of four-dimensional, risk-adapted stereotactic body radiotherapy (SBRT) delivered while tracking respiratory motion in patients with primary and metastatic lung cancer located in the central chest. Methods: Fifty-eight central lesions of 56 patients (39 with primary, 17 with metastatic tumors) were treated. Fifteen tumors located near the esophagus were treated with 6 fractions of 8 Gy. Other tumors were treated according to the following dose escalation scheme: 5 fractions of 9 Gy (n = 6), then 5 fractions of 10 Gy (n = 15), and finally 5 fractions of 12 Gy (n = 22). Results: Dose constraints for critical structures were generally achieved; in 21 patients the coverage of the PTV was reduced below 95% to protect adjacent organs at risk. At a median follow-up of 23 months, the actuarial 2-years local tumor control was 85% for tumors treated with a BED >100 Gy compared to 60% for tumors treated with a BED ⩽100 Gy. No grade 4 or 5 toxicity was observed. Acute grade 1–2 esophagitis was observed in 11% of patients. Conclusion: SBRT of central lung lesions can be safely delivered, with promising early tumor control in patients many of whom have severe comorbid conditions.

  8. Tumor motion in lung cancers: An overview of four-dimensional radiotherapy treatment of lung cancers

    Directory of Open Access Journals (Sweden)

    Anusheel Munshi

    2017-01-01

    Full Text Available Most modern radiotherapy centers have adopted contouring based treatment. Sparing of the normal structures has been made more achievable than ever before by use of technologies such as Intensity Modulated Radiotherapy (IMRT and Image guided radiotherapy (IGRT. However, unlike, sites such as brain or head neck, thorax is a site in active motion, mostly contributed by patient's respiratory movement. 4 D radiotherapy, that addresses the issues of motion in thoracic tumours answers this critical question. The present article outlines the scope of need for 4 D radiotherapy and discusses the options available for 4 D treatments of cancer patients.

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

    International Nuclear Information System (INIS)

    Siva, Shankar; Pham, Daniel; Gill, Suki; Bressel, Mathias; Dang, Kim; Devereux, Thomas; Kron, Tomas; Foroudi, Farshad

    2013-01-01

    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

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

    International Nuclear Information System (INIS)

    Zhang Peng; Hugo, Geoffrey D.; Yan Di

    2008-01-01

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

  11. Speed and amplitude of lung tumor motion precisely detected in four-dimensional setup and in real-time tumor-tracking radiotherapy

    International Nuclear Information System (INIS)

    Shirato, Hiroki; Suzuki, Keishiro; Sharp, Gregory C.; Fujita, Katsuhisa R.T.; Onimaru, Rikiya; Fujino, Masaharu; Kato, Norio; Osaka, Yasuhiro; Kinoshita, Rumiko; Taguchi, Hiroshi; Onodera, Shunsuke; Miyasaka, Kazuo

    2006-01-01

    Background: To reduce the uncertainty of registration for lung tumors, we have developed a four-dimensional (4D) setup system using a real-time tumor-tracking radiotherapy system. Methods and Materials: During treatment planning and daily setup in the treatment room, the trajectory of the internal fiducial marker was recorded for 1 to 2 min at the rate of 30 times per second by the real-time tumor-tracking radiotherapy system. To maximize gating efficiency, the patient's position on the treatment couch was adjusted using the 4D setup system with fine on-line remote control of the treatment couch. Results: The trajectory of the marker detected in the 4D setup system was well visualized and used for daily setup. Various degrees of interfractional and intrafractional changes in the absolute amplitude and speed of the internal marker were detected. Readjustments were necessary during each treatment session, prompted by baseline shifting of the tumor position. Conclusion: The 4D setup system was shown to be useful for reducing the uncertainty of tumor motion and for increasing the efficiency of gated irradiation. Considering the interfractional and intrafractional changes in speed and amplitude detected in this study, intercepting radiotherapy is the safe and cost-effective method for 4D radiotherapy using real-time tracking technology

  12. Conceptual formulation on four-dimensional inverse planning for intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    Lee, Louis; Ma Yunzhi; Xing Lei; Ye Yinyu

    2009-01-01

    Four-dimensional computed tomography (4DCT) offers an extra dimension of 'time' on the three-dimensional patient model with which we can incorporate target motion in radiation treatment (RT) planning and delivery in various ways such as in the concept of internal target volume, in gated treatment or in target tracking. However, for all these methodologies, different phases are essentially considered as non-interconnected independent phases for the purpose of optimization, in other words, the 'time' dimension has yet to be incorporated explicitly in the optimization algorithm and fully exploited. In this note, we have formulated a new 4D inverse planning technique that treats all the phases in the 4DCT as one single entity in the optimization. The optimization is formulated as a quadratic problem for disciplined convex programming that enables the problem to be analyzed and solved efficiently. In the proof-of-principle examples illustrated, we show that the temporal information of the spatial relation of the target and organs at risk could be 'exchanged' amongst different phases so that an appropriate weighting of dose deposition could be allocated to each phase, thus enabling a treatment with a tight target margin and a full duty cycle otherwise not achievable by either of the aforementioned methodologies. Yet there are practical issues to be solved in the 4D RT planning and delivery. The 4D concept in the optimization we have formulated here does provide insight on how the 'time' dimension can be exploited in the 4D optimization process. (note)

  13. Dosimetric Advantages of Four-Dimensional Adaptive Image-Guided Radiotherapy for Lung Tumors Using Online Cone-Beam Computed Tomography

    International Nuclear Information System (INIS)

    Harsolia, Asif; Hugo, Geoffrey D.; Kestin, Larry L.; Grills, Inga S.; Yan Di

    2008-01-01

    Purpose: This study compares multiple planning techniques designed to improve accuracy while allowing reduced planning target volume (PTV) margins though image-guided radiotherapy (IGRT) with four-dimensional (4D) cone-beam computed tomography (CBCT). Methods and Materials: Free-breathing planning and 4D-CBCT scans were obtained in 8 patients with lung tumors. Four plans were generated for each patient: 3D-conformal, 4D-union, 4D-offline adaptive with a single correction (offline ART), and 4D-online adaptive with daily correction (online ART). For the 4D-union plan, the union of gross tumor volumes from all phases of the 4D-CBCT was created with a 5-mm expansion applied for setup uncertainty. For offline and online ART, the gross tumor volume was delineated at the mean position of tumor motion from the 4D-CBCT. The PTV margins were calculated from the random components of tumor motion and setup uncertainty. Results: Adaptive IGRT techniques provided better PTV coverage with less irradiated normal tissues. Compared with 3D plans, mean relative decreases in PTV volumes were 15%, 39%, and 44% using 4D-union, offline ART, and online ART planning techniques, respectively. This resulted in mean lung volume receiving ≥ 20Gy (V20) relative decreases of 21%, 23%, and 31% and mean lung dose relative decreases of 16%, 26%, and 31% for the 4D-union, 4D-offline ART, and 4D-online ART, respectively. Conclusions: Adaptive IGRT using CBCT is feasible for the treatment of patients with lung tumors and significantly decreases PTV volume and dose to normal tissues, allowing for the possibility of dose escalation. All analyzed 4D planning strategies resulted in improvements over 3D plans, with 4D-online ART appearing optimal

  14. Efficient approach for determining four-dimensional computed tomography-based internal target volume in stereotactic radiotherapy of lung cancer

    International Nuclear Information System (INIS)

    Yeo, Seung Gu; Kim, Eun Seog

    2013-01-01

    This study aimed to investigate efficient approaches for determining internal target volume (ITV) from four-dimensional computed tomography (4D CT) images used in stereotactic body radiotherapy (SBRT) for patients with early-stage non-small cell lung cancer (NSCLC). 4D CT images were analyzed for 15 patients who received SBRT for stage I NSCLC. Three different ITVs were determined as follows: combining clinical target volume (CTV) from all 10 respiratory phases (ITV 10Phases ); combining CTV from four respiratory phases, including two extreme phases (0% and 50%) plus two intermediate phases (20% and 70%) (ITV 4Phases ); and combining CTV from two extreme phases (ITV 2Phases ). The matching index (MI) of ITV 4Phases and ITV 2Phases was defined as the ratio of ITV 4Phases and ITV 2Phases , respectively, to the ITV 10Phases . The tumor motion index (TMI) was defined as the ratio of ITV 10Phases to CTV mean , which was the mean of 10 CTVs delineated on 10 respiratory phases. The ITVs were significantly different in the order of ITV 10Phases , ITV 4Phases , and ITV 2Phases (all p 4Phases was significantly higher than that of ITV 2Phases (p 4Phases was inversely related to TMI (r = -0.569, p = 0.034). In a subgroup with low TMI (n = 7), ITV 4Phases was not statistically different from ITV 10Phases (p = 0.192) and its MI was significantly higher than that of ITV 2Phases (p = 0.016). The ITV 4Phases may be an efficient approach alternative to optimal ITV 10Phases in SBRT for early-stage NSCLC with less tumor motion.

  15. Audit of radiation dose delivered in time-resolved four-dimensional computed tomography in a radiotherapy department

    International Nuclear Information System (INIS)

    Hubbard, Patricia; Calllahan, Jason; Cramb, Jim; Budd, Ray

    2015-01-01

    To review the dose delivered to patients in time-resolved computed tomography (4D CT) used for radiotherapy treatment planning. 4D CT is used at Peter MacCallum Cancer Centre since July 2007 for radiotherapy treatment planning using a Philips Brilliance Wide Bore CT scanner (16 slice, helical 4D CT acquisition). All scans are performed at 140 kVp and reconstructed in 10 datasets for different phases of the breathing cycle. Dose records were analysed retrospectively for 387 patients who underwent 4D CT procedures between 2007 and 2013. A total of 444 4D CT scans were acquired with the majority of them (342) being for lung cancer radiotherapy. Volume CT dose index (CTDIvol) as recorded over this period was fairly constant at approximately 20 mGy for adults. The CTDI for 4D CT for lung cancers of 19.6 ± 9.3 mGy (n = 168, mean ± 1SD) was found to be 63% higher than CTDIs for conventional CT scans for lung patients that were acquired in the same period (CTDIvol 12 ± 4 mGy, sample of n = 25). CTDI and dose length product (DLP) increased with increasing field of view; however, no significant difference between DLPs for different indications (breast, kidney, liver and lung) could be found. Breathing parameters such as breathing rate or pattern did not affect dose. 4D CT scans can be acquired for radiotherapy treatment planning with a dose less than twice the one required for conventional CT scanning.

  16. 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)

    Mohammed, Nasiruddin; Kestin, Larry; Grills, Inga; Shah, Chirag; Glide-Hurst, Carri; Yan, Di; Ionascu, Dan

    2012-01-01

    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 (T L N). 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) T L N: 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 T L N. 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 T L N 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.

  17. 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

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, Nasiruddin; Kestin, Larry; Grills, Inga; Shah, Chirag; Glide-Hurst, Carri; Yan, Di [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Ionascu, Dan, E-mail: Dan.ionascu@beaumont.edu [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)

    2012-03-15

    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 (T{sub L}N). 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) T{sub L}N: 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 T{sub L}N. 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 T{sub L}N 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.

  18. SU-E-T-437: Four-Dimensional Treatment Planning for Lung VMAT-SBRT

    International Nuclear Information System (INIS)

    Hashimoto, M; Takashina, M; Koizumi, M; Oohira, S; Ueda, Y; Miyazaki, M; Isono, M; Masaoka, A; Teshima, T

    2015-01-01

    Purpose: To assess optimal treatment planning approach of Volumetric Modulated Arc Therapy for lung Stereotactic Body Radiation Therapy (VMAT-SBRT). Methods: Subjects were 10 patients with lung cancer who had undergone 4DCT. The internal target volume (ITV) volume ranged from 2.6 to 16.5cm 3 and the tumor motion ranged from 0 to 2cm. From 4DCT, which was binned into 10 respiratory phases, 4 image data sets were created; maximum intensity projection (MIP), average intensity projection (AIP), AIP with the ITV replaced by 0HU (RITV-AIP) and RITV-AIP with the planning target volume (PTV) minus the internal target volume was set to −200 HU (HR-AIP). VMAT-SBRT plans were generated on each image set for a patient. 48Gy was prescribed to 95% of PTV. The plans were recalculated on all phase images of 4DCT and the dose distributions were accumulated using a deformable image registration software MIM Maestro™ as the 4D calculated dose to the gross tumor volume (GTV). The planned dose to the ITV and 4D calculated dose to the GTV were compared. Results: In AIP plan, 10 patients average of all dose parameters (D1%, D-mean, and D99%) discrepancy were 1Gy or smaller. MIP and RITV-AIP plans resulted in having common tendency and larger discrepancy than AIP plan. The 4D dose was lower than the planned dose, and 10 patients average of all dose parameters discrepancy were in range 1.3 to 2.6Gy. HR-AIP plan had the largest discrepancy in our trials. 4D calculated D1%, D-mean, and D99% were resulted in 3.0, 4.1, and 6.1Gy lower than the expected in plan, respectively. Conclusion: For all patients, the dose parameters expected in AIP plan approximated to 4D calculated. Using AIP image set seems optimal treatment planning approach of VMAT-SBRT for a mobile tumor. Funding Support: This work was supported by the Japan Society for the Promotion of Science Core-to-Core program (No. 23003)

  19. Real-time respiration monitoring using the radiotherapy treatment beam and four-dimensional computed tomography (4DCT)-a conceptual study

    International Nuclear Information System (INIS)

    Lu Weiguo; Ruchala, Kenneth J; Chen, Ming-Li; Chen, Quan; Olivera, Gustavo H

    2006-01-01

    Real-time knowledge of intra-fraction motion, such as respiration, is essential for four-dimensional (4D) radiotherapy. Surrogate-based and internal-fiducial-based methods may suffer from one or many drawbacks such as false correlation, being invasive, delivering extra patient radiation, and requiring complicated hardware and software development and implementation. In this paper we develop a simple non-surrogate, non-invasive method to monitor respiratory motion during radiotherapy treatments in real time. This method directly utilizes the treatment beam and thus imposes no additional radiation to the patient. The method requires a pre-treatment 4DCT and a real-time detector system. The method combines off-line processes with on-line processes. The off-line processes include 4DCT imaging and pre-calculating detector signals at each phase of the 4DCT based on the planned fluence map and the detector response function. The on-line processes include measuring detector signal from the treatment beam, and correlating the measured detector signal with the pre-calculated signals. The respiration phase is determined as the position of peak correlation. We tested our method with extensive simulations based on a TomoTherapy machine and a 4DCT of a lung cancer patient. Three types of simulations were implemented to mimic the clinical situations. Each type of simulation used three different TomoTherapy delivery sinograms, each with 800 to 1000 projections, as input fluences. Three arbitrary breathing patterns were simulated and two dose levels, 2 Gy/fraction and 2 cGy/fraction, were used for simulations to study the robustness of this method against detector quantum noise. The algorithm was used to determine the breathing phases and this result was compared with the simulated breathing patterns. For the 2 Gy/fraction simulations, the respiration phases were accurately determined within one phase error in real time for most projections of the treatment, except for a few

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  1. PLANNING NATIONAL RADIOTHERAPY SERVICES

    Directory of Open Access Journals (Sweden)

    Eduardo eRosenblatt

    2014-11-01

    Full Text Available Countries, states and island nations often need forward planning of their radiotherapy services driven by different motives. Countries without radiotherapy services sponsor patients to receive radiotherapy abroad. They often engage professionals for a feasibility study in order to establish whether it would be more cost-beneficial to establish a radiotherapy facility. Countries where radiotherapy services have developed without any central planning, find themselves in situations where many of the available centres are private and thus inaccessible for a majority of patients with limited resources. Government may decide to plan ahead when a significant exodus of cancer patients travel to another country for treatment, thus exposing the failure of the country to provide this medical service for its citizens. In developed countries the trigger has been the existence of highly visible waiting lists for radiotherapy revealing a shortage of radiotherapy equipment.This paper suggests that there should be a systematic and comprehensive process of long-term planning of radiotherapy services at the national level, taking into account the regulatory infrastructure for radiation protection, planning of centres, equipment, staff, education pr

  2. 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)

    Clements, N.; Kron, T.; Roxby, P.; Franich, R.; Dunn, L.; Aarons, Y.; Chesson, B.; Siva, S.; Duplan, D.; Ball, D.

    2013-01-01

    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

  3. 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

    Energy Technology Data Exchange (ETDEWEB)

    Clements, N. [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne 3002, Australia and Department of Applied Sciences, RMIT University, Melbourne 3001 (Australia); Kron, T.; Roxby, P. [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne 3002 (Australia); Franich, R.; Dunn, L. [Department of Applied Sciences, RMIT University, Melbourne 3001 (Australia); Aarons, Y.; Chesson, B. [Department of Radiation Therapy, Peter MacCallum Cancer Centre, East Melbourne 3002 (Australia); Siva, S.; Duplan, D.; Ball, D. [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne 3002 (Australia)

    2013-02-15

    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

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

    Directory of Open Access Journals (Sweden)

    Wang W

    2016-08-01

    Full Text Available 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 thoracic primary esophageal cancer. Materials and methods: Forty-three patients with esophageal cancer underwent 3DCT and 4DCT simulation scans during free breathing. The motions of primary tumors located in the proximal (group A, middle (group B, and distal (group C thoracic esophagus were obtained from the 4DCT scans. PTV3D was defined on 3DCT using the tumor motion measured based on 4DCT, PTV conventional (PTVconv was defined on 3DCT by adding a 1.0 cm margin to the clinical target volume, and PTV4D was defined as the union of the target volumes contoured on the ten phases of the 4DCT images. The centroid positions, volumetric differences, and dice similarity coefficients were evaluated for all PTVs. Results: The median centroid shifts between PTV3D and PTV4D and between PTVconv and PTV4D in all three dimensions were <0.3 cm for the three groups. The median size ratios of PTV4D to PTV3D were 0.80, 0.88, and 0.71, and PTV4D to PTVconv were 0.67, 0.73, and 0.76 (χ2=–3.18, –2.98, and –3.06; P=0.001, 0.003, and 0.002 for groups A, B, and C, respectively. The dice similarity coefficients were 0.87, 0.90, and 0.81 between PTV4D and PTV3D and 0.80, 0.84, and 0.83 between PTV4D and PTVconv (χ2=–3.18, –2.98, and –3.06; P=0.001, 0.003, and 0.002 for groups A, B, and C, respectively. The difference between the degree of inclusion of PTV4D in PTV3D and that of PTV4D in PTVconv was <2% for all groups. Compared with PTVconv, the amount of irradiated normal tissue

  5. Assessing Respiration-Induced Tumor Motion and Internal Target Volume Using Four-Dimensional Computed Tomography for Radiotherapy of Lung Cancer

    International Nuclear Information System (INIS)

    Liu, H. Helen; Balter, Peter; Tutt, Teresa; Choi, Bum; Zhang, Joy; Wang, Catherine; Chi, Melinda; Luo Dershan; Pan Tinsu; Hunjan, Sandeep; Starkschall, George; Rosen, Isaac; Prado, Karl; Liao Zhongxing; Chang, Joe; Komaki, Ritsuko; Cox, James D.; Mohan, Radhe; Dong Lei

    2007-01-01

    Purpose: To assess three-dimensional tumor motion caused by respiration and internal target volume (ITV) for radiotherapy of lung cancer. Methods and Materials: Respiration-induced tumor motion was analyzed for 166 tumors from 152 lung cancer patients, 57.2% of whom had Stage III or IV non-small-cell lung cancer. All patients underwent four-dimensional computed tomography (4DCT) during normal breathing before treatment. The expiratory phase of 4DCT images was used as the reference set to delineate gross tumor volume (GTV). Gross tumor volumes on other respiratory phases and resulting ITVs were determined using rigid-body registration of 4DCT images. The association of GTV motion with various clinical and anatomic factors was analyzed statistically. Results: The proportions of tumors that moved >0.5 cm along the superior-inferior (SI), lateral, and anterior-posterior (AP) axes during normal breathing were 39.2%, 1.8%, and 5.4%, respectively. For 95% of the tumors, the magnitude of motion was less than 1.34 cm, 0.40 cm, and 0.59 cm along the SI, lateral, and AP directions. The principal component of tumor motion was in the SI direction, with only 10.8% of tumors moving >1.0 cm. The tumor motion was found to be associated with diaphragm motion, the SI tumor location in the lung, size of the GTV, and disease T stage. Conclusions: Lung tumor motion is primarily driven by diaphragm motion. The motion of locally advanced lung tumors is unlikely to exceed 1.0 cm during quiet normal breathing except for small lesions located in the lower half of the lung

  6. 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.

  7. Quantification of Mediastinal and Hilar Lymph Node Movement Using Four-Dimensional Computed Tomography Scan: Implications for Radiation Treatment Planning

    International Nuclear Information System (INIS)

    Sher, David J.; Wolfgang, John A.; Niemierko, Andrzej; Choi, Noah C.

    2007-01-01

    Purpose: To quantitatively describe mediastinal and hilar lymph node movement in patients with lymph node-positive lung cancer. Methods and Materials: Twenty-four patients with lung cancer who underwent four-dimensional computed tomography scanning at Massachusetts General Hospital were included in the study. The maximum extent of superior motion of the superior border was measured, as well as the maximum inferior movement of the inferior border. The average of these two values is defined as the peak-to-peak movement. This process was repeated for mediolateral (ML) and anterior-posterior (AP) movement. Linear regression was used to determine lymph node characteristics associated with peak-to-peak movement. Various uniform expansions were investigated to determine the expansion margins necessary to ensure complete internal target volume (ITV) coverage. Results: The mean peak-to-peak displacements of paratracheal lymph nodes were 4 mm (craniocaudal [CC]), 2 mm (ML), and 2 mm (AP). For subcarinal lymph nodes, the mean peak-to-peak movements were 6 mm (CC), 4 mm (ML), and 2 mm (AP). The mean peak-to-peak displacements of hilar lymph nodes were 7 mm (CC), 1 mm (ML), and 4 mm (AP). On multivariate analysis, lymph node station and lymph node size were significantly related to peak-to-peak movement. Expansions of 8 mm for paratracheal nodes and 13 mm for subcarinal and hilar nodes would have been necessary to cover the ITV of 95% of these nodal masses. Conclusions: Subcarinal and hilar lymph nodes may move substantially throughout the respiratory cycle. In the absence of patient-specific information on nodal motion, expansions of at least 8 mm, 13 mm, and 13 mm should be considered to cover the ITV of paratracheal, subcarinal, and hilar lymph nodes, respectively

  8. Four-dimensional computed tomographic analysis of esophageal mobility during normal respiration

    NARCIS (Netherlands)

    Dieleman, Edith M. T.; Senan, Suresh; Vincent, Andrew; Lagerwaard, Frank J.; Slotman, Ben J.; van Sörnsen de Koste, John R.

    2007-01-01

    BACKGROUND: Chemo-radiotherapy for thoracic tumors can result in high-grade radiation esophagitis. Treatment planning to reduce esophageal irradiation requires organ motion to be accounted for. In this study, esophageal mobility was assessed using four-dimensional computed tomography (4DCT). METHODS

  9. Investigation of pancreas tumour movements and of their potential markers by four-dimensional scanography: implication for image-guided radiotherapy

    International Nuclear Information System (INIS)

    Huguet, F.; Yorke, E.; Davidson, M.; Zhang, Z.; Jackson, A.; Mageras, G.; Wu, A.; Goodman, K.

    2011-01-01

    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

  10. Computerised tomography in radiotherapy planning

    International Nuclear Information System (INIS)

    Badcock, P.C.

    1983-01-01

    This study evaluates the effectiveness of computed tomography as an adjunct to radiotherapy planning. Until recently, acquisition of accurate data concerning tumour anatomy lagged behind other developments in radiotherapy. With the advent of computer-tomography (CT), these data can be displayed and transmitted to a treatment planning computer. It is concluded that the greatest inaccuracies in the radiation treatment of patients are to be found in both the inadequate delineation of the target volume within the patient and changes in body outline relative to the target volume over the length of the irradiated volume. The technique was useful in various subgroups (pelvic, intra-thoracic and chest-wall tumours) and for those patients being treated palliatively. With an estimated improvement in cure rate of 4.5% and cost-effective factors of between 3.3 and 5, CT-assisted radiotherapy planning appears to be a worthwhile procedure. (orig.)

  11. On four dimensional mirror symmetry

    International Nuclear Information System (INIS)

    Losev, A.; Nekrasov, N.; Shatashvili, S.

    2000-01-01

    A conjecture relating instanton calculus in four dimensional supersymmetric theories and the deformation theory of Lagrangian submanifolds in C 2r invariant under a (subgroup of) Sp(2r,Z) is formulated. This is a four dimensional counterpart of the mirror symmetry of topological strings (relating Gromov-Witten invariants and generalized variations of Hodge structure). (orig.)

  12. Construction of a remote radiotherapy planning system

    International Nuclear Information System (INIS)

    Ogawa, Yoshihiro; Nemoto, Kenji; Takahashi, Chiaki; Takai, Yoshihiro; Yamada, Shogo; Seiji, Hiromasa; Sasaki, Kazuya

    2005-01-01

    We constructed a remote radiotherapy planning system, and we examined the usefulness of and faults in our system in this study. Two identical radiotherapy planning systems, one installed at our institution and the other installed at an affiliated hospital, were used for radiotherapy planning. The two systems were connected by a wide area network (WAN), using a leased line. Beam data for the linear accelerator at the affiliated hospital were installed in the two systems. During the period from December 2001 to December 2002, 43 remote radiotherapy plans were made using this system. Data were transmitted using a file transfer protocol (FTP) software program. The 43 radiotherapy plans examined in this study consisted of 13 ordinary radiotherapy plans, 28 radiotherapy plans sent to provide assistance for medical residents, and 2 radiotherapy plans for emergency cases. There were ten minor planning changes made in radiotherapy plans sent to provide assistance for medical residents. Our remote radiotherapy planning system based on WAN using a leased line is useful for remote radiotherapy, with advantages for both radiation oncologists and medical residents. (author)

  13. A Four-Dimensional Approach

    African Journals Online (AJOL)

    ... of East Asian Students in English-speaking Countries: A Four-Dimensional ... country's language greatly shapes all aspects of the student's international education ... Taking this ecological approach will help clearly define the role that home ...

  14. Four Dimensional Trace Space Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, M.

    2005-02-10

    Future high energy colliders and FELs (Free Electron Lasers) such as the proposed LCLS (Linac Coherent Light Source) at SLAC require high brightness electron beams. In general a high brightness electron beam will contain a large number of electrons that occupy a short longitudinal duration, can be focused to a small transverse area while having small transverse divergences. Therefore the beam must have a high peak current and occupy small areas in transverse phase space and so have small transverse emittances. Additionally the beam should propagate at high energy and have a low energy spread to reduce chromatic effects. The requirements of the LCLS for example are pulses which contain 10{sup 10} electrons in a temporal duration of 10 ps FWHM with projected normalized transverse emittances of 1{pi} mm mrad[1]. Currently the most promising method of producing such a beam is the RF photoinjector. The GTF (Gun Test Facility) at SLAC was constructed to produce and characterize laser and electron beams which fulfill the LCLS requirements. Emittance measurements of the electron beam at the GTF contain evidence of strong coupling between the transverse dimensions of the beam. This thesis explores the effects of this coupling on the determination of the projected emittances of the electron beam. In the presence of such a coupling the projected normalized emittance is no longer a conserved quantity. The conserved quantity is the normalized full four dimensional phase space occupied by the beam. A method to determine the presence and evaluate the strength of the coupling in emittance measurements made in the laboratory is developed. A method to calculate the four dimensional volume the beam occupies in phase space using quantities available in the laboratory environment is also developed. Results of measurements made of the electron beam at the GTF that demonstrate these concepts are presented and discussed.

  15. SU-G-JeP4-06: Evaluation of Interfractional and Intrafractional Tumor Motion in Stereotactic Liver Radiotherapy, Based On Four-Dimensional Cone-Beam Computed Tomography Using Fiducial Markers

    International Nuclear Information System (INIS)

    Shimohigashi, Y; Araki, F; Toya, R; Maruyama, M; Nakaguchi, Y

    2016-01-01

    Purpose: The purpose of this study was to evaluate the interfractional and intrafractional motion of liver tumors in stereotactic body radiation therapy (SBRT), based on four-dimensional cone-beam computed tomography using fiducial markers. (4D-CBCT). Methods: Seven patients with liver tumors were treated by SBRT with abdominal compression (AC) in five fractions with image guidance based on 4D-CBCT. The 4D-CBCT studies were performed to determine the individualized internal margin for the planning simulation. The interfractional and intrafractional changes of liver tumor motion for all patients was measured, based on the planning simulation 4D-CBCT, pre-SBRT 4D-CBCT, and post-SBRT 4D-CBCT. The interfractional motion change was calculated from the difference in liver tumor amplitude on pre-SBRT 4D-CBCT relative to that of the planning simulation 4D-CBCT for each fraction. The intrafractional motion change was calculated from the difference between the liver tumor amplitudes of the pre- and post-SBRT 4D-CBCT for each fraction. Significant interfractional and intrafractional changes in liver tumor motion were defined as a change ≥3 mm. Statistical analysis was performed using the Pearson correlation. Results: The values of the mean amplitude of liver tumor, as indicated by planning simulation 4D-CBCT, were 1.6 ± 0.8 mm, 1.6 ± 0.9 mm, and 4.9 ± 2.2 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. Pearson correlation coefficients between the liver tumor amplitudes, based on planning simulation 4D-CBCT, and pre-SBRT 4D-CBCT during fraction treatment in the LR, AP, and SI directions were 0.6, 0.7, and 0.8, respectively. Interfractional and intrafractional motion changes of ≥3 mm occurred in 23% and 3% of treatment fractions, respectively. Conclusion: The interfractional and intrafractional changes of liver tumor motion were small in most patients who received liver SBRT with AC. In addition, planning

  16. SU-G-JeP4-06: Evaluation of Interfractional and Intrafractional Tumor Motion in Stereotactic Liver Radiotherapy, Based On Four-Dimensional Cone-Beam Computed Tomography Using Fiducial Markers

    Energy Technology Data Exchange (ETDEWEB)

    Shimohigashi, Y [Department of Radiological Technology, Kumamoto University Hospital, Department of Graduate School of Health Sciences, Kumamoto University (Japan); Araki, F [Department of Health Sciences, Kumamoto University (Japan); Toya, R [Department of Radiation Oncology, Kumamoto University Hospital (Japan); Department of Human Oncology, University of Wisconsin School of Medicine and Public Health (United States); Maruyama, M; Nakaguchi, Y [Department of Radiological Technology, Kumamoto University Hospital (Japan)

    2016-06-15

    Purpose: The purpose of this study was to evaluate the interfractional and intrafractional motion of liver tumors in stereotactic body radiation therapy (SBRT), based on four-dimensional cone-beam computed tomography using fiducial markers. (4D-CBCT). Methods: Seven patients with liver tumors were treated by SBRT with abdominal compression (AC) in five fractions with image guidance based on 4D-CBCT. The 4D-CBCT studies were performed to determine the individualized internal margin for the planning simulation. The interfractional and intrafractional changes of liver tumor motion for all patients was measured, based on the planning simulation 4D-CBCT, pre-SBRT 4D-CBCT, and post-SBRT 4D-CBCT. The interfractional motion change was calculated from the difference in liver tumor amplitude on pre-SBRT 4D-CBCT relative to that of the planning simulation 4D-CBCT for each fraction. The intrafractional motion change was calculated from the difference between the liver tumor amplitudes of the pre- and post-SBRT 4D-CBCT for each fraction. Significant interfractional and intrafractional changes in liver tumor motion were defined as a change ≥3 mm. Statistical analysis was performed using the Pearson correlation. Results: The values of the mean amplitude of liver tumor, as indicated by planning simulation 4D-CBCT, were 1.6 ± 0.8 mm, 1.6 ± 0.9 mm, and 4.9 ± 2.2 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. Pearson correlation coefficients between the liver tumor amplitudes, based on planning simulation 4D-CBCT, and pre-SBRT 4D-CBCT during fraction treatment in the LR, AP, and SI directions were 0.6, 0.7, and 0.8, respectively. Interfractional and intrafractional motion changes of ≥3 mm occurred in 23% and 3% of treatment fractions, respectively. Conclusion: The interfractional and intrafractional changes of liver tumor motion were small in most patients who received liver SBRT with AC. In addition, planning

  17. Monte Carlo Treatment Planning for Advanced Radiotherapy

    DEFF Research Database (Denmark)

    Cronholm, Rickard

    This Ph.d. project describes the development of a workflow for Monte Carlo Treatment Planning for clinical radiotherapy plans. The workflow may be utilized to perform an independent dose verification of treatment plans. Modern radiotherapy treatment delivery is often conducted by dynamically...... modulating the intensity of the field during the irradiation. The workflow described has the potential to fully model the dynamic delivery, including gantry rotation during irradiation, of modern radiotherapy. Three corner stones of Monte Carlo Treatment Planning are identified: Building, commissioning...... and validation of a Monte Carlo model of a medical linear accelerator (i), converting a CT scan of a patient to a Monte Carlo compliant phantom (ii) and translating the treatment plan parameters (including beam energy, angles of incidence, collimator settings etc) to a Monte Carlo input file (iii). A protocol...

  18. New four-dimensional symmetry

    International Nuclear Information System (INIS)

    Hsu, J.P.

    1976-01-01

    A new picture of nature is proposed in which there are only two fundamental universal constants anti e (identical with e/c) and dirac constant (identical with dirac constant/c). The theory is developed within the framework of a new four-dimensional symmetry which is constructed on the basis of the Poincare--Einstein principle of relativity for the laws of physics and the Newtonian concept of time. One obtains a new space--light transformation law, a velocity-addition law, and so on. In this symmetry scheme, the speed of light is constant and is completely relative. The new theory is logically self-consistent, and it moreover is in agreement with all previously established experimental facts, such as the ''lifetime dilatation'' of unstable particles, the Michelson--Morley experiment, etc. There is a difference relative to the usual theory, though, in that our theory predicts a new law for the Doppler frequency shift, which can be tested experimentally by measuring the second-order frequency shift

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

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  20. IMRT plan verification in radiotherapy

    International Nuclear Information System (INIS)

    Vlk, P.

    2006-01-01

    This article describes the procedure for verification of IMRT (Intensity modulated radiation therapy) plan, which is used in the Oncological Institute of St. Elisabeth in Bratislava. It contains basic description of IMRT technology and developing a deployment plan for IMRT planning system CORVUS 6.0, the device Mimic (Multilammelar intensity modulated collimator) and the overall process of verifying the schedule created. The aim of verification is particularly good control of the functions of MIMIC and evaluate the overall reliability of IMRT planning. (author)

  1. Radiotherapy Treatment Planning for Testicular Seminoma

    International Nuclear Information System (INIS)

    Wilder, Richard B.; Buyyounouski, Mark K.; Efstathiou, Jason A.; Beard, Clair J.

    2012-01-01

    Virtually all patients with Stage I testicular seminoma are cured regardless of postorchiectomy management. For patients treated with adjuvant radiotherapy, late toxicity is a major concern. However, toxicity may be limited by radiotherapy techniques that minimize radiation exposure of healthy normal tissues. This article is an evidence-based review that provides radiotherapy treatment planning recommendations for testicular seminoma. The minority of Stage I patients who choose adjuvant treatment over surveillance may be considered for (1) para-aortic irradiation to 20 Gy in 10 fractions, or (2) carboplatin chemotherapy consisting of area under the curve, AUC = 7 × 1−2 cycles. Two-dimensional radiotherapy based on bony anatomy is a simple and effective treatment for Stage IIA or IIB testicular seminoma. Centers with expertise in vascular and nodal anatomy may consider use of anteroposterior–posteroanterior fields based on three-dimensional conformal radiotherapy instead. For modified dog-leg fields delivering 20 Gy in 10 fractions, clinical studies support placement of the inferior border at the top of the acetabulum. Clinical and nodal mapping studies support placement of the superior border of all radiotherapy fields at the top of the T12 vertebral body. For Stage IIA and IIB patients, an anteroposterior–posteroanterior boost is then delivered to the adenopathy with a 2-cm margin to the block edge. The boost dose consists of 10 Gy in 5 fractions for Stage IIA and 16 Gy in 8 fractions for Stage IIB. Alternatively, bleomycin, etoposide, and cisplatin chemotherapy for 3 cycles or etoposide and cisplatin chemotherapy for 4 cycles may be delivered to Stage IIA or IIB patients (e.g., if they have a horseshoe kidney, inflammatory bowel disease, or a history of radiotherapy).

  2. Radiotherapy Treatment Planning for Testicular Seminoma

    Energy Technology Data Exchange (ETDEWEB)

    Wilder, Richard B., E-mail: richardbwilder@yahoo.com [Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL (United States); Buyyounouski, Mark K. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Efstathiou, Jason A. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Beard, Clair J. [Department of Radiation Oncology, Dana-Farber/Brigham and Women' s Cancer Center, Boston, MA (United States)

    2012-07-15

    Virtually all patients with Stage I testicular seminoma are cured regardless of postorchiectomy management. For patients treated with adjuvant radiotherapy, late toxicity is a major concern. However, toxicity may be limited by radiotherapy techniques that minimize radiation exposure of healthy normal tissues. This article is an evidence-based review that provides radiotherapy treatment planning recommendations for testicular seminoma. The minority of Stage I patients who choose adjuvant treatment over surveillance may be considered for (1) para-aortic irradiation to 20 Gy in 10 fractions, or (2) carboplatin chemotherapy consisting of area under the curve, AUC = 7 Multiplication-Sign 1-2 cycles. Two-dimensional radiotherapy based on bony anatomy is a simple and effective treatment for Stage IIA or IIB testicular seminoma. Centers with expertise in vascular and nodal anatomy may consider use of anteroposterior-posteroanterior fields based on three-dimensional conformal radiotherapy instead. For modified dog-leg fields delivering 20 Gy in 10 fractions, clinical studies support placement of the inferior border at the top of the acetabulum. Clinical and nodal mapping studies support placement of the superior border of all radiotherapy fields at the top of the T12 vertebral body. For Stage IIA and IIB patients, an anteroposterior-posteroanterior boost is then delivered to the adenopathy with a 2-cm margin to the block edge. The boost dose consists of 10 Gy in 5 fractions for Stage IIA and 16 Gy in 8 fractions for Stage IIB. Alternatively, bleomycin, etoposide, and cisplatin chemotherapy for 3 cycles or etoposide and cisplatin chemotherapy for 4 cycles may be delivered to Stage IIA or IIB patients (e.g., if they have a horseshoe kidney, inflammatory bowel disease, or a history of radiotherapy).

  3. Radiotherapy treatment planning linear-quadratic radiobiology

    CERN Document Server

    Chapman, J Donald

    2015-01-01

    Understand Quantitative Radiobiology from a Radiation Biophysics PerspectiveIn the field of radiobiology, the linear-quadratic (LQ) equation has become the standard for defining radiation-induced cell killing. Radiotherapy Treatment Planning: Linear-Quadratic Radiobiology describes tumor cell inactivation from a radiation physics perspective and offers appropriate LQ parameters for modeling tumor and normal tissue responses.Explore the Latest Cell Killing Numbers for Defining Iso-Effective Cancer TreatmentsThe book compil

  4. Planned combined radiotherapy and surgery

    International Nuclear Information System (INIS)

    Silverman, C.L.; Marks, J.E.

    1987-01-01

    Though the planned combined use of surgery and radiation has been shown to be beneficial for other tumors, the authors feel that the present evidence is far from persuasive in demonstrating a definite superiority of combined therapy over surgery or radiation alone for advanced laryngeal tumors. The actuarial or disease-free survival rates for patients treated with combined therapy have not been significantly increased over those obtained with a single modality in any randomized, well-controlled study, although the trend is toward improved local regional control. Many of the retrospective studies are probably flawed by selection bias; the patients selected for combined treatment generally have more advanced cancers and represent a worse prognostic group. It is clear from this review that the positive value of irradiation for advanced transglottic and supraglottic tumors needs to be documented by a controlled study that compares surgery alone with salvage radiation at time of recurrence to surgery plus adjuvant radiation. The authors feel that such a study is needed to put to rest the present controversy before they can advocate a course of treatment that is expensive, time-consuming, and difficult for the patients to tolerate owing to severe acute side effects and potentially morbid late effects (xerostomia, necrosis) that can greatly lessen the quality of life for these patients

  5. Super integrable four-dimensional autonomous mappings

    International Nuclear Information System (INIS)

    Capel, H W; Sahadevan, R; Rajakumar, S

    2007-01-01

    A systematic investigation of the complete integrability of a fourth-order autonomous difference equation of the type w(n + 4) = w(n)F(w(n + 1), w(n + 2), w(n + 3)) is presented. We identify seven distinct families of four-dimensional mappings which are super integrable and have three (independent) integrals via a duality relation as introduced in a recent paper by Quispel, Capel and Roberts (2005 J. Phys. A: Math. Gen. 38 3965-80). It is observed that these seven families can be related to the four-dimensional symplectic mappings with two integrals including all the four-dimensional periodic reductions of the integrable double-discrete modified Korteweg-deVries and sine-Gordon equations treated in an earlier paper by two of us (Capel and Sahadevan 2001 Physica A 289 86-106)

  6. Treatment planning systems for high precision radiotherapy

    International Nuclear Information System (INIS)

    Deshpande, D.D.

    2008-01-01

    Computerized Treatment Planning System (TPS) play an important role in radiotherapy with the intent to maximize tumor control and minimize normal tissue complications. Treatment planning during earlier days was generally carried out through the manual summations of standard isodose charts on to patient body contours that were generated by direct tracing or lead wire representation, and relied heavily on the careful choices of beam weights and wedging. Since then there had been tremendous advances in field of Radiation Oncology in last few decades. The linear accelerators had evolved from MLC's to IGRT, the techniques like 3DCRT, IMRT has become almost routine affair. The simulation has seen transition from simple 2D film/fluoroscopy localization to CT Simulator with added development in PET, PET- CT and MR imaging. The Networking and advances in computer technology has made it possible to direct transfer of Images, contours to the treatment planning systems

  7. Accuracy requirements in radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Buzdar, S. A.; Afzal, M.; Nazir, A.; Gadhi, M. A.

    2013-01-01

    Radiation therapy attempts to deliver ionizing radiation to the tumour and can improve the survival chances and/or quality of life of patients. There are chances of errors and uncertainties in the entire process of radiotherapy that may affect the accuracy and precision of treatment management and decrease degree of conformation. All expected inaccuracies, like radiation dose determination, volume calculation, complete evaluation of the full extent of the tumour, biological behaviour of specific tumour types, organ motion during radiotherapy, imaging, biological/molecular uncertainties, sub-clinical diseases, microscopic spread of the disease, uncertainty in normal tissue responses and radiation morbidity need sound appreciation. Conformity can be increased by reduction of such inaccuracies. With the yearly increase in computing speed and advancement in other technologies the future will provide the opportunity to optimize a greater number of variables and reduce the errors in the treatment planning process. In multi-disciplined task of radiotherapy, efforts are needed to overcome the errors and uncertainty, not only by the physicists but also by radiologists, pathologists and oncologists to reduce molecular and biological uncertainties. The radiation therapy physics is advancing towards an optimal goal that is definitely to improve accuracy where necessary and to reduce uncertainty where possible. (author)

  8. Telemedicine in radiotherapy treatment planning: requirements and applications

    International Nuclear Information System (INIS)

    Olsen, D.R.; Bruland, O.S.; Davis, B.J.

    2000-01-01

    Telemedicine facilitates decentralized radiotherapy services by allowing remote treatment planning and quality assurance of treatment delivery. A prerequisite is digital storage of relevant data and an efficient and reliable telecommunication system between satellite units and the main radiotherapy clinic. The requirements of a telemedicine system in radiotherapy is influenced by the level of support needed. In this paper we differentiate between three categories of telemedicine support in radiotherapy. Level 1 features video conferencing and display of radiotherapy images and dose plans. Level 2 involves replication of selected data from the radiotherapy database - facilitating remote treatment planning and evaluation. Level 3 includes real-time, remote operations, e.g. target volume delineation and treatment planning performed by the team at the satellite unit under supervision and guidance from more experienced colleagues at the main clinic. (author)

  9. Automated four-dimensional Monte Carlo workflow using log files and real-time motion monitoring

    International Nuclear Information System (INIS)

    Sibolt, P; Andersen, C E; Cronholm, R O; Heath, E; Behrens, C F

    2017-01-01

    With emerging techniques for tracking and gating methods in radiotherapy of lung cancer patients, there is an increasing need for efficient four-dimensional Monte Carlo (4DMC) based quality assurance (QA). An automated and flexible workflow for 4DMC QA, based on the 4DdefDOSXYZnrc user code, has been developed in python. The workflow has been tested and verified using an in-house developed dosimetry system comprised of a dynamic thorax phantom constructed for plastic scintillator dosimetry. The workflow is directly compatible with any treatment planning system and can also be triggered by the appearance of linac log files. It has minimum user interaction and, with the use of linac log files, it provides a method for verification of the actually delivered dose in the patient geometry. (paper)

  10. Automated radiotherapy treatment plan integrity verification

    Energy Technology Data Exchange (ETDEWEB)

    Yang Deshan; Moore, Kevin L. [Department of Radiation Oncology, School of Medicine, Washington University in Saint Louis, St. Louis, Missouri 63110 (United States)

    2012-03-15

    Purpose: In our clinic, physicists spend from 15 to 60 min to verify the physical and dosimetric integrity of radiotherapy plans before presentation to radiation oncology physicians for approval. The purpose of this study was to design and implement a framework to automate as many elements of this quality control (QC) step as possible. Methods: A comprehensive computer application was developed to carry out a majority of these verification tasks in the Philips PINNACLE treatment planning system (TPS). This QC tool functions based on both PINNACLE scripting elements and PERL sub-routines. The core of this technique is the method of dynamic scripting, which involves a PERL programming module that is flexible and powerful for treatment plan data handling. Run-time plan data are collected, saved into temporary files, and analyzed against standard values and predefined logical rules. The results were summarized in a hypertext markup language (HTML) report that is displayed to the user. Results: This tool has been in clinical use for over a year. The occurrence frequency of technical problems, which would cause delays and suboptimal plans, has been reduced since clinical implementation. Conclusions: In addition to drastically reducing the set of human-driven logical comparisons, this QC tool also accomplished some tasks that are otherwise either quite laborious or impractical for humans to verify, e.g., identifying conflicts amongst IMRT optimization objectives.

  11. Automated radiotherapy treatment plan integrity verification

    International Nuclear Information System (INIS)

    Yang Deshan; Moore, Kevin L.

    2012-01-01

    Purpose: In our clinic, physicists spend from 15 to 60 min to verify the physical and dosimetric integrity of radiotherapy plans before presentation to radiation oncology physicians for approval. The purpose of this study was to design and implement a framework to automate as many elements of this quality control (QC) step as possible. Methods: A comprehensive computer application was developed to carry out a majority of these verification tasks in the Philips PINNACLE treatment planning system (TPS). This QC tool functions based on both PINNACLE scripting elements and PERL sub-routines. The core of this technique is the method of dynamic scripting, which involves a PERL programming module that is flexible and powerful for treatment plan data handling. Run-time plan data are collected, saved into temporary files, and analyzed against standard values and predefined logical rules. The results were summarized in a hypertext markup language (HTML) report that is displayed to the user. Results: This tool has been in clinical use for over a year. The occurrence frequency of technical problems, which would cause delays and suboptimal plans, has been reduced since clinical implementation. Conclusions: In addition to drastically reducing the set of human-driven logical comparisons, this QC tool also accomplished some tasks that are otherwise either quite laborious or impractical for humans to verify, e.g., identifying conflicts amongst IMRT optimization objectives.

  12. Effect of Novel Amplitude/Phase Binning Algorithm on Commercial Four-Dimensional Computed Tomography Quality

    International Nuclear Information System (INIS)

    Olsen, Jeffrey R.; Lu Wei; Hubenschmidt, James P.; Nystrom, Michelle M.; Klahr, Paul; Bradley, Jeffrey D.; Low, Daniel A.; Parikh, Parag J.

    2008-01-01

    Purpose: Respiratory motion is a significant source of anatomic uncertainty in radiotherapy planning and can result in errors of portal size and the subsequent radiation dose. Although four-dimensional computed tomography allows for more accurate analysis of the respiratory cycle, breathing irregularities during data acquisition can cause considerable image distortions. The aim of this study was to examine the effect of respiratory irregularities on four-dimensional computed tomography, and to evaluate a novel image reconstruction algorithm using percentile-based tagging of the respiratory cycle. Methods and Materials: Respiratory-correlated helical computed tomography scans were acquired for 11 consecutive patients. The inspiration and expiration data sets were reconstructed using the default phase-based method, as well as a novel respiration percentile-based method with patient-specific metrics to define the ranges of the reconstruction. The image output was analyzed in a blinded fashion for the phase- and percentile-based reconstructions to determine the prevalence and severity of the image artifacts. Results: The percentile-based algorithm resulted in a significant reduction in artifact severity compared with the phase-based algorithm, although the overall artifact prevalence did not differ between the two algorithms. The magnitude of differences in respiratory tag placement between the phase- and percentile-based algorithms correlated with the presence of image artifacts. Conclusion: The results of our study have indicated that our novel four-dimensional computed tomography reconstruction method could be useful in detecting clinically relevant image distortions that might otherwise go unnoticed and to reduce the image distortion associated with some respiratory irregularities. Additional work is necessary to assess the clinical impact on areas of possible irregular breathing

  13. Dosimetry audit of radiotherapy treatment planning systems

    International Nuclear Information System (INIS)

    Bulski, Wojciech; Chelminski, Krzysztof; Rostkowska, Joanna

    2015-01-01

    In radiotherapy Treatment Planning Systems (TPS) various calculation algorithms are used. The accuracy of dose calculations has to be verified. Numerous phantom types, detectors and measurement methodologies are proposed to verify the TPS calculations with dosimetric measurements. A heterogeneous slab phantom has been designed within a Coordinated Research Project (CRP) of the IAEA. The heterogeneous phantom was developed in the frame of the IAEA CRP. The phantom consists of frame slabs made with polystyrene and exchangeable inhomogeneity slabs equivalent to bone or lung tissue. Special inserts allow to position thermoluminescent dosimeters (TLD) capsules within the polystyrene slabs below the bone or lung equivalent slabs and also within the lung equivalent material. Additionally, there are inserts that allow to position films or ionisation chamber in the phantom. Ten Polish radiotherapy centres (of 30 in total) were audited during on-site visits. Six different TPSs and five calculation algorithms were examined in the presence of inhomogeneities. Generally, most of the results from TLD were within 5 % tolerance. Differences between doses calculated by TPSs and measured with TLD did not exceed 4 % for bone and polystyrene equivalent materials. Under the lung equivalent material, on the beam axis the differences were lower than 5 %, whereas inside the lung equivalent material, off the beam axis, in some cases they were of around 7 %. The TLD results were confirmed with the ionisation chamber measurements. The comparison results of the calculations and the measurements allow to detect limitations of TPS calculation algorithms. The audits performed with the use of heterogeneous phantom and TLD seem to be an effective tool for detecting the limitations in the TPS performance or beam configuration errors at audited radiotherapy departments. (authors)

  14. Dosimetry audit of radiotherapy treatment planning systems.

    Science.gov (United States)

    Bulski, Wojciech; Chełmiński, Krzysztof; Rostkowska, Joanna

    2015-07-01

    In radiotherapy Treatment Planning Systems (TPS) various calculation algorithms are used. The accuracy of dose calculations has to be verified. Numerous phantom types, detectors and measurement methodologies are proposed to verify the TPS calculations with dosimetric measurements. A heterogeneous slab phantom has been designed within a Coordinated Research Project (CRP) of the IAEA. The heterogeneous phantom was developed in the frame of the IAEA CRP. The phantom consists of frame slabs made with polystyrene and exchangeable inhomogeneity slabs equivalent to bone or lung tissue. Special inserts allow to position thermoluminescent dosimeters (TLD) capsules within the polystyrene slabs below the bone or lung equivalent slabs and also within the lung equivalent material. Additionally, there are inserts that allow to position films or ionisation chamber in the phantom. Ten Polish radiotherapy centres (of 30 in total) were audited during on-site visits. Six different TPSs and five calculation algorithms were examined in the presence of inhomogeneities. Generally, most of the results from TLD were within 5 % tolerance. Differences between doses calculated by TPSs and measured with TLD did not exceed 4 % for bone and polystyrene equivalent materials. Under the lung equivalent material, on the beam axis the differences were lower than 5 %, whereas inside the lung equivalent material, off the beam axis, in some cases they were of around 7 %. The TLD results were confirmed with the ionisation chamber measurements. The comparison results of the calculations and the measurements allow to detect limitations of TPS calculation algorithms. The audits performed with the use of heterogeneous phantom and TLD seem to be an effective tool for detecting the limitations in the TPS performance or beam configuration errors at audited radiotherapy departments. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Automatic liver contouring for radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Li, Dengwang; Kapp, Daniel S; Xing, Lei; Liu, Li

    2015-01-01

    To develop automatic and efficient liver contouring software for planning 3D-CT and four-dimensional computed tomography (4D-CT) for application in clinical radiation therapy treatment planning systems.The algorithm comprises three steps for overcoming the challenge of similar intensities between the liver region and its surrounding tissues. First, the total variation model with the L1 norm (TV-L1), which has the characteristic of multi-scale decomposition and an edge-preserving property, is used for removing the surrounding muscles and tissues. Second, an improved level set model that contains both global and local energy functions is utilized to extract liver contour information sequentially. In the global energy function, the local correlation coefficient (LCC) is constructed based on the gray level co-occurrence matrix both of the initial liver region and the background region. The LCC can calculate the correlation of a pixel with the foreground and background regions, respectively. The LCC is combined with intensity distribution models to classify pixels during the evolutionary process of the level set based method. The obtained liver contour is used as the candidate liver region for the following step. In the third step, voxel-based texture characterization is employed for refining the liver region and obtaining the final liver contours.The proposed method was validated based on the planning CT images of a group of 25 patients undergoing radiation therapy treatment planning. These included ten lung cancer patients with normal appearing livers and ten patients with hepatocellular carcinoma or liver metastases. The method was also tested on abdominal 4D-CT images of a group of five patients with hepatocellular carcinoma or liver metastases. The false positive volume percentage, the false negative volume percentage, and the dice similarity coefficient between liver contours obtained by a developed algorithm and a current standard delineated by the expert group

  16. PET/CT Based Dose Planning in Radiotherapy

    DEFF Research Database (Denmark)

    Berthelsen, Anne Kiil; Jakobsen, Annika Loft; Sapru, Wendy

    2011-01-01

    radiotherapy planning with PET/CT prior to the treatment. The PET/CT, including the radiotherapy planning process as well as the radiotherapy process, is outlined in detail. The demanding collaboration between mould technicians, nuclear medicine physicians and technologists, radiologists and radiology......This mini-review describes how to perform PET/CT based radiotherapy dose planning and the advantages and possibilities obtained with the technique for radiation therapy. Our own experience since 2002 is briefly summarized from more than 2,500 patients with various malignant diseases undergoing...... technologists, radiation oncologists, physicists, and dosimetrists is emphasized. We strongly believe that PET/CT based radiotherapy planning will improve the therapeutic output in terms of target definition and non-target avoidance and will play an important role in future therapeutic interventions in many...

  17. Definition of internal target volume and domestric study for hepatocellular carcinoma using four-dimensional CT

    International Nuclear Information System (INIS)

    Xi Mian; Liu Mengzhong; Deng Xiaowu; Zhang Li; Huang Xiaoyan; Cai Ling

    2009-01-01

    Objective: To define individualized internal target volume (ITV) for hepatocellular carcinoma using four-dimensional (4D) CT, and to compare the differences in target volume definition and dose distribution among 3D, 4D and respiratory-gated plans. Methods: 4DCT scanning was obtained for 12 patients with hepatocellular. Gross tumor volume (GTV), clinical target volume (CTV) and normal tissues were contoured on all 10 respiratory phases of 4DCT images. The 3D, 4D and gated treatment plans were prepared for each patient using three different planning target volumes (PTVs): 1) PTV 3D was derived from a single CTV plus conventional margins; 2) PTV 4D was derived from ITV 4D , which encompassed all 10 CTVs plus setup margins (SMs); 3) PT Gating was derived from ITV Gating , which encompassed 3 CTVs within gating-window at end-expiration plus SMs. The PTV volume and dose distribution were compared among different plans. Results: The PTV3D was the largest in all 12 patients, but still missed partial target volume in 5 patients when comparing with PTV4D. Both the 4D plans and the gated plans spared more normal tissues than the 3D plans, especially the liver. Without increasing normal tissue dose, the 4D plans allowed for increasing the calculated dose from (50.8 ± 2.0) Gy (3D plans) to (54.7 ± 3.3) Gy, and the gated plans could further increase the dose to (58.0 ± 3.9) Gy. Conclusions: The 4DCT-based plans can ensure optimal target coverage with less irradiation of normal tissues and allow dose escalation when compared with 3D plans. Respiratory gated radiotherapy can further reduce the target volumes to spare more surrounding tissues, especially for patients with large extent of respiratory mobility. (authors)

  18. SU-F-P-32: A Phantom Study of Accuracy of Four-Dimensional Cone-Beam CT (4D-CBCT) Vs. Three-Dimensional Cone Beam CT (3D-CBCT) in Image Guided Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    He, R; Morris, B; Duggar, N; Markovich, A; Standford, J; Lu, J; Yang, C [University of Mississippi Med. Center, Jackson, MS (United States)

    2016-06-15

    Purpose: SymmetryTM 4D IGRT system of Elekta has been installed at our institution, which offers the 4D CBCT registration option. This study is to evaluate the accuracy of 4D CBCT system by using the CIRS 4D motion phantom and to perform a feasibility study on the implementation of 4D-CBCT as image guidance for SBRT treatment. Methods: The 3D and 4D CT image data sets are acquired using the CIRS motion phantom on a Philips large bore CT simulator. The motion was set as 0.5 cm superior and inferior directions with 6 seconds recycle time. The 4D CT data were sorted as 10 phases. One identifiable part of the 4D CT QA insert from CIRS phantom was used as the target. The ITV MIP was drawn based on maximum intensity projection (MIP) and transferred as a planning structure into 4D CBCT system. Then the 3D CBCT and 4D CBCT images were taken and registered with the free breath (3D), MIP (4D) and average intensity projection (AIP)(4D) reference data sets. The couch shifts (X, Y, Z) are recorded and compared. Results: Table 1 listed the twelve couch shifts based on the registration of MIP, AIP and free breath CT data sets with 3D CBCT and 4D CBCT for both whole body and local registration. X, Y and Z represent couch shifts in the direction of the right-left, superior-inferior and anterior-posterior. The biggest differences of 0.73 cm and 0.57 cm are noted in the free breath CT data with 4D CBCT and 3D CBCT data registration. Fig. 1 and Fig. 2 are the shift analysis in diagram. Fig. 3 shows the registration. Conclusion: Significant differences exist in the shifts corresponding with the direction of target motion. Further investigations are ongoing.

  19. Planning National Radiotherapy Services: A Practical Tool (Russian Edition)

    International Nuclear Information System (INIS)

    2015-01-01

    The current and future burden of cancer incidence in developing countries requires the planning, establishment and upgrading of radiotherapy services at the national level. This publication is a practical guide outlining the main issues at stake when planning national radiotherapy services. It provides an assessment of the cancer burden, evaluates the existing resources, and determines what is needed and how to cover the gap in a resource oriented rational way. The publication will be of practical value to decision makers and programme managers in public health facing the organization or reorganization of radiotherapy services in their countries.

  20. Four-dimensional CT-based evaluation of volumetric modulated arc therapy for abdominal lymph node metastasis from hepatocellular carcinoma

    International Nuclear Information System (INIS)

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

    2012-01-01

    This study aimed to identify the potential benefits and limitations of a new volumetric modulated arc therapy (VMAT) planning system in Monaco, compared with conventional intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT). Four-dimensional CT scans of 13 patients with abdominal lymph node metastasis from hepatocellular carcinoma were selected. Internal target volume was defined as the combined volume of clinical target volumes (CTVs) in the multiple four-dimensional computed tomography (4DCT) phases. Dose prescription was set to 45 Gy for the planning target volume (PTV) in daily 3.0-Gy fractions. The PTV dose coverage, organs at risk (OAR) doses, delivery parameters and treatment accuracy were assessed. Compared with 3DCRT, both VMAT and IMRT provided a systematic improvement in PTV coverage and homogeneity. Planning objectives were not fulfilled for the right kidney, in which the 3DCRT plans exceeded the dose constraints in two patients. Equivalent target coverage and sparing of OARs were achieved with VMAT compared with IMRT. The number of MU/fraction was 462±68 (3DCRT), 564±105 (IMRT) and 601±134 (VMAT), respectively. Effective treatment times were as follows: 1.8±0.2 min (3DCRT), 6.1±1.5 min (IMRT) and 4.8±1.0 min (VMAT). This study suggests that the VMAT plans generated in Monaco improved delivery efficiency for equivalent dosimetric quality to IMRT, and were superior to 3DCRT in target coverage and sparing of most OARs. However, the superiority of VMAT over IMRT in delivery efficiency is limited. (author)

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

    International Nuclear Information System (INIS)

    Low, Daniel A.; Nystrom, Michelle; Kalinin, Eugene; Parikh, Parag; Dempsey, James F.; Bradley, Jeffrey D.; Mutic, Sasa; Wahab, Sasha H.; Islam, Tareque; Christensen, Gary; Politte, David G.; Whiting, Bruce R.

    2003-01-01

    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 cm 3 . An analysis of sagittal and

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-03-15

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

  3. Conformal Radiotherapy: Physics, Treatment Planning and Verification. Proceedings book

    Energy Technology Data Exchange (ETDEWEB)

    De Wagter, C [ed.

    1995-12-01

    The goal of conformal radiotherapy is to establish radiation dose distributions that conform tightly to the target volume in view of limiting radiation to normal tissues. Conformal radiotherapy significantly improves both local control and palliation and thus contributes to increase survival and to improve the quality of life. The subjects covered by the symposium include : (1) conformal radiotherapy and multi-leaf collimation; (2) three dimensional imaging; (3) treatment simulation, planning and optimization; (4) quality assurance; and (5) dosimetry. The book of proceedings contains the abstracts of the invited lectures, papers and poster presentations as well as the full papers of these contributions.

  4. Conformal Radiotherapy: Physics, Treatment Planning and Verification. Proceedings book

    International Nuclear Information System (INIS)

    De Wagter, C.

    1995-12-01

    The goal of conformal radiotherapy is to establish radiation dose distributions that conform tightly to the target volume in view of limiting radiation to normal tissues. Conformal radiotherapy significantly improves both local control and palliation and thus contributes to increase survival and to improve the quality of life. The subjects covered by the symposium include : (1) conformal radiotherapy and multi-leaf collimation; (2) three dimensional imaging; (3) treatment simulation, planning and optimization; (4) quality assurance; and (5) dosimetry. The book of proceedings contains the abstracts of the invited lectures, papers and poster presentations as well as the full papers of these contributions

  5. Patients with hip prosthesis: radiotherapy treatment planning considerations

    International Nuclear Information System (INIS)

    Ganesh, K.M.; Supe, Sanjay S.

    2000-01-01

    The number of patients with hip prosthesis undergoing radiotherapy for pelvic cancer worldwide is increasing. This might be of importance depending on the materials in the prosthesis and whether any of the treatment fields are involved in the prosthesis. Radiotherapy planning involving the pelvic region of patients having total hip prosthesis has been found to be difficult due to the effect of the prosthesis on the dose distribution. This review is intended to project dosimetric considerations and possible solutions to this uncommon problem

  6. Magnetic resonance imaging in radiotherapy treatment planning

    NARCIS (Netherlands)

    Moerland, Marinus Adriaan

    1996-01-01

    From its inception in the early 1970's up to the present, magnetic resonance imaging (MRI) has evolved into a sophisticated technique, which has aroused considerable interest in var- ious subelds of medicine including radiotherapy. MRI is capable of imaging in any plane and does not use ionizing

  7. Integration of the radiotherapy irradiation planning in the digital workflow

    International Nuclear Information System (INIS)

    Roehner, F.; Schmucker, M.; Henne, K.; Bruggmoser, G.; Grosu, A.L.; Frommhold, H.; Heinemann, F.E.; Momm, F.

    2013-01-01

    Background and purpose: At the Clinic of Radiotherapy at the University Hospital Freiburg, all relevant workflow is paperless. After implementing the Operating Schedule System (OSS) as a framework, all processes are being implemented into the departmental system MOSAIQ. Designing a digital workflow for radiotherapy irradiation planning is a large challenge, it requires interdisciplinary expertise and therefore the interfaces between the professions also have to be interdisciplinary. For every single step of radiotherapy irradiation planning, distinct responsibilities have to be defined and documented. All aspects of digital storage, backup and long-term availability of data were considered and have already been realized during the OSS project. Method: After an analysis of the complete workflow and the statutory requirements, a detailed project plan was designed. In an interdisciplinary workgroup, problems were discussed and a detailed flowchart was developed. The new functionalities were implemented in a testing environment by the Clinical and Administrative IT Department (CAI). After extensive tests they were integrated into the new modular department system. Results and conclusion: The Clinic of Radiotherapy succeeded in realizing a completely digital workflow for radiotherapy irradiation planning. During the testing phase, our digital workflow was examined and afterwards was approved by the responsible authority. (orig.)

  8. Radiotherapy

    International Nuclear Information System (INIS)

    Zedgenidze, G.A.; Kulikov, V.A.; Mardynskij, Yu.S.

    1984-01-01

    The technique for roentgenotopometric and medicamentous preparation of patients for radiotherapy has been reported in detail. The features of planning and performing of remote, intracavitary and combined therapy in urinary bladder cancer are considered. The more effective methods of radiotherapy have been proposed taking into account own experience as well as literature data. The comparative evaluation of treatment results and prognosis are given. Radiation pathomorphism of tumors and tissues of urinary bladder is considered in detail. The problems of diagnosis, prophylaxis and treatment of complications following radiodiagnosis and radiotherapy in patients with urinary bladder cancer are illustrated widely

  9. 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

  10. Four-dimensional computed tomographic analysis of esophageal mobility during normal respiration

    International Nuclear Information System (INIS)

    Dieleman, Edith; Senan, Suresh; Vincent, Andrew; Lagerwaard, Frank J.; Slotman, Ben J.; Soernsen de Koste, John R. van

    2007-01-01

    Background: Chemo-radiotherapy for thoracic tumors can result in high-grade radiation esophagitis. Treatment planning to reduce esophageal irradiation requires organ motion to be accounted for. In this study, esophageal mobility was assessed using four-dimensional computed tomography (4DCT). Methods and Materials: Thoracic 4DCT scans were acquired on a 16-slice CT scanner in 29 patients. The outer esophageal wall was contoured in two extreme phases of respiration in 9 patients with nonesophageal malignancies. The displacement of the center of contour was measured at 2-cm intervals. In 20 additional patients with Stage I lung cancer, the esophagus was contoured in all 10 phases of each 4DCT at five defined anatomic levels. Both approaches were then applied to 4DCT scans of 4 patients who each had two repeat scans performed. A linear mixed effects model was constructed with fixed effects: measurement direction, measurement type, and measurement location along the cranio-caudal axis. Results: Measurement location and direction were significant descriptive parameters (Wald F-tests, p < 0.001), and the interaction term between the two was significant (p = 0.02). Medio-lateral mobility exceeded dorso-ventral mobility in the lower half of the esophagus but was of a similar magnitude in the upper half. Margins that would have incorporated all movement in medio-lateral and dorso-ventral directions were 5 mm proximally, 7 mm and 6 mm respectively in the mid-esophagus, and 9 mm and 8 mm respectively in the distal esophagus. Conclusions: The distal esophagus shows more mobility. Margins for mobility that can encompass all movement were derived for use in treatment planning, particularly for stereotactic radiotherapy

  11. Extended supersymmetry in four-dimensional Euclidean space

    International Nuclear Information System (INIS)

    McKeon, D.G.C.; Sherry, T.N.

    2000-01-01

    Since the generators of the two SU(2) groups which comprise SO(4) are not Hermitian conjugates of each other, the simplest supersymmetry algebra in four-dimensional Euclidean space more closely resembles the N=2 than the N=1 supersymmetry algebra in four-dimensional Minkowski space. An extended supersymmetry algebra in four-dimensional Euclidean space is considered in this paper; its structure resembles that of N=4 supersymmetry in four-dimensional Minkowski space. The relationship of this algebra to the algebra found by dimensionally reducing the N=1 supersymmetry algebra in ten-dimensional Euclidean space to four-dimensional Euclidean space is examined. The dimensional reduction of N=1 super Yang-Mills theory in ten-dimensional Minkowski space to four-dimensional Euclidean space is also considered

  12. Markov chain Monte Carlo methods in radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Hugtenburg, R.P.

    2001-01-01

    The Markov chain method can be used to incorporate measured data in Monte Carlo based radiotherapy treatment planning. This paper shows that convergence to the measured data, within the target precision, is achievable. Relative output factors for blocked fields and oblique beams are shown to compare well with independent measurements according to the same criterion. (orig.)

  13. Progress of radiotherapy by three-dimensional treatment planning

    International Nuclear Information System (INIS)

    Imada, Hajime; Nomoto, Satoshi; Takahashi, Hiroyuki; Nakata, Hajime

    1998-01-01

    The recent progress of three-dimensional radiation treatment planning was reviewed. And clinical cases such as lung cancer and breast cancer are introduced. In the University of Occupational and Development Health, the treatment system FOCUS which is made up of CT simulator and linac was used mainly. Three-dimensional treatment planning was carried for about 90% of 330 patients who underwent radiotherapy for one year. The target becomes to be accurate and dose distribution with all CT slices in radiation field can be confirmed by using three-dimensional radiation treatment planning apparatus. High dose irradiation localized to tumor part is possible. Relations between total dose and volume of normal tissue and/or tumor can be estimated numerically and easily by DVH. A prediction of indication and affection became possible by this procedure. In conclusion, generalization of three-dimensional radiation treatment planning will bring progress of more effective radiotherapy with less adverse reaction. (K.H.). 21 refs

  14. Radiotherapy facilities: Master planning and concept design considerations

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-08-15

    This publication provides guidelines on how to plan a radiotherapy facility in terms of the strategic master planning process including the legal, technical and infrastructure requirements. It outlines a risk assessment methodology, a typical project work plan and describes the professional expertise required for the implementation of such a project. Generic templates for a block design are suggested, which include possibilities for future expansion. These templates can be overlaid onto the designated site such that the most efficient workflow between the main functional areas can be ensured. A sample checklist is attached to act as a guideline for project management and to indicate the critical stages in the process where technical expert assistance may be needed. The publication is aimed at professionals and administrators involved in infrastructure development, planning and facility management, as well as engineers, building contractors and radiotherapy professionals.

  15. Radiotherapy Facilities: Master Planning and Concept Design Considerations (Russian Edition)

    International Nuclear Information System (INIS)

    2015-01-01

    This publication provides guidelines on how to plan a radiotherapy facility in terms of the strategic master planning process including the legal, technical and infrastructure requirements. It outlines a risk assessment methodology and a typical project work plan, and describes the professional expertise required for the implementation of such a project. Generic templates for a block design are suggested, which include possibilities for future expansion. These templates can be overlaid onto the designated site such that the most efficient workflow between the main functional areas can be ensured. A sample checklist is attached to act as a guideline for project management and to indicate the critical stages in the process where technical expert assistance may be needed. The publication is aimed at professionals and administrators involved in infrastructure development, planning and facility management, as well as engineers, building contractors and radiotherapy professionals

  16. Radiotherapy facilities: Master planning and concept design considerations

    International Nuclear Information System (INIS)

    2014-01-01

    This publication provides guidelines on how to plan a radiotherapy facility in terms of the strategic master planning process including the legal, technical and infrastructure requirements. It outlines a risk assessment methodology, a typical project work plan and describes the professional expertise required for the implementation of such a project. Generic templates for a block design are suggested, which include possibilities for future expansion. These templates can be overlaid onto the designated site such that the most efficient workflow between the main functional areas can be ensured. A sample checklist is attached to act as a guideline for project management and to indicate the critical stages in the process where technical expert assistance may be needed. The publication is aimed at professionals and administrators involved in infrastructure development, planning and facility management, as well as engineers, building contractors and radiotherapy professionals

  17. Unmanned Aerial System Four-Dimensional Gunnery Training Device Development

    Science.gov (United States)

    2017-10-01

    Aerial System (UAS) Four-Dimensional Gunnery Training Device: Training Effectiveness Assessment (James & Miller, in press). 31 Technical ...Research Product 2018-05 Unmanned Aerial System Four-Dimensional Gunnery Training Device Development David R. James...for the Department of the Army by Northrop Grumman Corporation. Technical review by Thomas Rhett Graves, Ph.D., U.S. Army Research Institute

  18. Inverse Operation of Four-dimensional Vector Matrix

    OpenAIRE

    H J Bao; A J Sang; H X Chen

    2011-01-01

    This is a new series of study to define and prove multidimensional vector matrix mathematics, which includes four-dimensional vector matrix determinant, four-dimensional vector matrix inverse and related properties. There are innovative concepts of multi-dimensional vector matrix mathematics created by authors with numerous applications in engineering, math, video conferencing, 3D TV, and other fields.

  19. Four-dimensional strings: Phenomenology and model building

    International Nuclear Information System (INIS)

    Quiros, M.

    1989-01-01

    In these lectures we will review some of the last developments in string theories leading to the construction of realistic four-dimensional string models. Special attention will be paid to world-sheet and space-time supersymmetry, modular invariance and model building for supersymmetric and (tachyon-free) nonsupersymmetric ten and four-dimensional models. (orig.)

  20. Bayesian network models for error detection in radiotherapy plans

    International Nuclear Information System (INIS)

    Kalet, Alan M; Ford, Eric C; Phillips, Mark H; Gennari, John H

    2015-01-01

    The purpose of this study is to design and develop a probabilistic network for detecting errors in radiotherapy plans for use at the time of initial plan verification. Our group has initiated a multi-pronged approach to reduce these errors. We report on our development of Bayesian models of radiotherapy plans. Bayesian networks consist of joint probability distributions that define the probability of one event, given some set of other known information. Using the networks, we find the probability of obtaining certain radiotherapy parameters, given a set of initial clinical information. A low probability in a propagated network then corresponds to potential errors to be flagged for investigation. To build our networks we first interviewed medical physicists and other domain experts to identify the relevant radiotherapy concepts and their associated interdependencies and to construct a network topology. Next, to populate the network’s conditional probability tables, we used the Hugin Expert software to learn parameter distributions from a subset of de-identified data derived from a radiation oncology based clinical information database system. These data represent 4990 unique prescription cases over a 5 year period. Under test case scenarios with approximately 1.5% introduced error rates, network performance produced areas under the ROC curve of 0.88, 0.98, and 0.89 for the lung, brain and female breast cancer error detection networks, respectively. Comparison of the brain network to human experts performance (AUC of 0.90 ± 0.01) shows the Bayes network model performs better than domain experts under the same test conditions. Our results demonstrate the feasibility and effectiveness of comprehensive probabilistic models as part of decision support systems for improved detection of errors in initial radiotherapy plan verification procedures. (paper)

  1. Characterisation of radiotherapy planning volumes using textural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nailon, William H.; Redpath, Anthony T.; McLaren, Duncan B. (Dept. of Oncology Physics, Edinburgh Cancer Centre, Western General Hospital, Edinburgh (United Kingdom))

    2008-08-15

    Computer-based artificial intelligence methods for classification and delineation of the gross tumour volume (GTV) on computerised tomography (CT) and magnetic resonance (MR) images do not, at present, provide the accuracy required for radiotherapy applications. This paper describes an image analysis method for classification of distinct regions within the GTV, and other clinically relevant regions, on CT images acquired on eight bladder cancer patients at the radiotherapy planning stage and thereafter at regular intervals during treatment. Statistical and fractal textural features (N=27) were calculated on the bladder, rectum and a control region identified on axial, coronal and sagittal CT images. Unsupervised classification results demonstrate that with a reduced feature set (N=3) the approach offers significant classification accuracy on axial, coronal and sagittal CT image planes and has the potential to be developed further for radiotherapy applications, particularly towards an automatic outlining approach

  2. Characterisation of radiotherapy planning volumes using textural analysis

    International Nuclear Information System (INIS)

    Nailon, William H.; Redpath, Anthony T.; McLaren, Duncan B.

    2008-01-01

    Computer-based artificial intelligence methods for classification and delineation of the gross tumour volume (GTV) on computerised tomography (CT) and magnetic resonance (MR) images do not, at present, provide the accuracy required for radiotherapy applications. This paper describes an image analysis method for classification of distinct regions within the GTV, and other clinically relevant regions, on CT images acquired on eight bladder cancer patients at the radiotherapy planning stage and thereafter at regular intervals during treatment. Statistical and fractal textural features (N=27) were calculated on the bladder, rectum and a control region identified on axial, coronal and sagittal CT images. Unsupervised classification results demonstrate that with a reduced feature set (N=3) the approach offers significant classification accuracy on axial, coronal and sagittal CT image planes and has the potential to be developed further for radiotherapy applications, particularly towards an automatic outlining approach

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

    International Nuclear Information System (INIS)

    Riegel, Adam C. B.A.; Chang, Joe Y.; Vedam, Sastry S.; Johnson, Valen; Chi, Pai-Chun Melinda; Pan, Tinsu

    2009-01-01

    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

  4. Gamma histograms for radiotherapy plan evaluation

    International Nuclear Information System (INIS)

    Spezi, Emiliano; Lewis, D. Geraint

    2006-01-01

    Background and purpose: The technique known as the 'γ evaluation method' incorporates pass-fail criteria for both distance-to-agreement and dose difference analysis of 3D dose distributions and provides a numerical index (γ) as a measure of the agreement between two datasets. As the γ evaluation index is being adopted in more centres as part of treatment plan verification procedures for 2D and 3D dose maps, the development of methods capable of encapsulating the information provided by this technique is recommended. Patients and methods: In this work the concept of γ index was extended to create gamma histograms (GH) in order to provide a measure of the agreement between two datasets in two or three dimensions. Gamma area histogram (GAH) and gamma volume histogram (GVH) graphs were produced using one or more 2D γ maps generated for each slice of the irradiated volume. GHs were calculated for IMRT plans, evaluating the 3D dose distribution from a commercial treatment planning system (TPS) compared to a Monte Carlo (MC) calculation used as reference dataset. Results: The extent of local anatomical inhomogenities in the plans under consideration was strongly correlated with the level of difference between reference and evaluated calculations. GHs provided an immediate visual representation of the proportion of the treated volume that fulfilled the γ criterion and offered a concise method for comparative numerical evaluation of dose distributions. Conclusions: We have introduced the concept of GHs and investigated its applications to the evaluation and verification of IMRT plans. The gamma histogram concept set out in this paper can provide a valuable technique for quantitative comparison of dose distributions and could be applied as a tool for the quality assurance of treatment planning systems

  5. Approximating convex Pareto surfaces in multiobjective radiotherapy planning

    International Nuclear Information System (INIS)

    Craft, David L.; Halabi, Tarek F.; Shih, Helen A.; Bortfeld, Thomas R.

    2006-01-01

    Radiotherapy planning involves inherent tradeoffs: the primary mission, to treat the tumor with a high, uniform dose, is in conflict with normal tissue sparing. We seek to understand these tradeoffs on a case-to-case basis, by computing for each patient a database of Pareto optimal plans. A treatment plan is Pareto optimal if there does not exist another plan which is better in every measurable dimension. The set of all such plans is called the Pareto optimal surface. This article presents an algorithm for computing well distributed points on the (convex) Pareto optimal surface of a multiobjective programming problem. The algorithm is applied to intensity-modulated radiation therapy inverse planning problems, and results of a prostate case and a skull base case are presented, in three and four dimensions, investigating tradeoffs between tumor coverage and critical organ sparing

  6. Radiation Planning Assistant - A Streamlined, Fully Automated Radiotherapy Treatment Planning System

    Science.gov (United States)

    Court, Laurence E.; Kisling, Kelly; McCarroll, Rachel; Zhang, Lifei; Yang, Jinzhong; Simonds, Hannah; du Toit, Monique; Trauernicht, Chris; Burger, Hester; Parkes, Jeannette; Mejia, Mike; Bojador, Maureen; Balter, Peter; Branco, Daniela; Steinmann, Angela; Baltz, Garrett; Gay, Skylar; Anderson, Brian; Cardenas, Carlos; Jhingran, Anuja; Shaitelman, Simona; Bogler, Oliver; Schmeller, Kathleen; Followill, David; Howell, Rebecca; Nelson, Christopher; Peterson, Christine; Beadle, Beth

    2018-01-01

    The Radiation Planning Assistant (RPA) is a system developed for the fully automated creation of radiotherapy treatment plans, including volume-modulated arc therapy (VMAT) plans for patients with head/neck cancer and 4-field box plans for patients with cervical cancer. It is a combination of specially developed in-house software that uses an application programming interface to communicate with a commercial radiotherapy treatment planning system. It also interfaces with a commercial secondary dose verification software. The necessary inputs to the system are a Treatment Plan Order, approved by the radiation oncologist, and a simulation computed tomography (CT) image, approved by the radiographer. The RPA then generates a complete radiotherapy treatment plan. For the cervical cancer treatment plans, no additional user intervention is necessary until the plan is complete. For head/neck treatment plans, after the normal tissue and some of the target structures are automatically delineated on the CT image, the radiation oncologist must review the contours, making edits if necessary. They also delineate the gross tumor volume. The RPA then completes the treatment planning process, creating a VMAT plan. Finally, the completed plan must be reviewed by qualified clinical staff. PMID:29708544

  7. Clinical considerations of Monte Carlo for electron radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Faddegon, Bruce; Balogh, Judith; Mackenzie, Robert; Scora, Daryl

    1998-01-01

    Technical requirements for Monte Carlo based electron radiotherapy treatment planning are outlined. The targeted overall accuracy for estimate of the delivered dose is the least restrictive of 5% in dose, 5 mm in isodose position. A system based on EGS4 and capable of achieving this accuracy is described. Experience gained in system design and commissioning is summarized. The key obstacle to widespread clinical use of Monte Carlo is lack of clinically acceptable measurement based methodology for accurate commissioning

  8. Automatic planning on hippocampal avoidance whole-brain radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shuo, E-mail: shuo0220@gmail.com; Zheng, Dandan; Zhang, Chi; Ma, Rongtao; Bennion, Nathan R.; Lei, Yu; Zhu, Xiaofeng; Enke, Charles A.; Zhou, Sumin

    2017-04-01

    Mounting evidence suggests that radiation-induced damage to the hippocampus plays a role in neurocognitive decline for patients receiving whole-brain radiotherapy (WBRT). Hippocampal avoidance whole-brain radiotherapy (HA-WBRT) has been proposed to reduce the putative neurocognitive deficits by limiting the dose to the hippocampus. However, urgency of palliation for patients as well as the complexities of the treatment planning may be barriers to protocol enrollment to accumulate further clinical evidence. This warrants expedited quality planning of HA-WBRT. Pinnacle{sup 3} Automatic treatment planning was designed to increase planning efficiency while maintaining or improving plan quality and consistency. The aim of the present study is to evaluate the performance of the Pinnacle{sup 3} Auto-Planning on HA-WBRT treatment planning. Ten patients previously treated for brain metastases were selected. Hippocampal volumes were contoured on T1 magnetic resonance (MR) images, and planning target volumes (PTVs) were generated based on RTOG0933. The following 2 types of plans were generated by Pinnacle{sup 3} Auto-Planning: the one with 2 coplanar volumetric modulated arc therapy (VMAT) arcs and the other with 9-field noncoplanar intensity-modulated radiation therapy (IMRT). D{sub 2%} and D{sub 98%} of PTV were used to calculate homogeneity index (HI). HI and Paddick Conformity index (CI) of PTV as well as D{sub 100%} and D{sub max} of the hippocampus were used to evaluate the plan quality. All the auto-plans met the dose coverage and constraint objectives based on RTOG0933. The auto-plans eliminated the necessity of generating pseudostructures by the planners, and it required little manual intervention which expedited the planning process. IMRT quality assurance (QA) results also suggest that all the auto-plans are practically acceptable on delivery. Pinnacle{sup 3} Auto-Planning generates acceptable plans by RTOG0933 criteria without time-consuming planning process. The

  9. Automatic planning on hippocampal avoidance whole-brain radiotherapy

    International Nuclear Information System (INIS)

    Wang, Shuo; Zheng, Dandan; Zhang, Chi; Ma, Rongtao; Bennion, Nathan R.; Lei, Yu; Zhu, Xiaofeng; Enke, Charles A.; Zhou, Sumin

    2017-01-01

    Mounting evidence suggests that radiation-induced damage to the hippocampus plays a role in neurocognitive decline for patients receiving whole-brain radiotherapy (WBRT). Hippocampal avoidance whole-brain radiotherapy (HA-WBRT) has been proposed to reduce the putative neurocognitive deficits by limiting the dose to the hippocampus. However, urgency of palliation for patients as well as the complexities of the treatment planning may be barriers to protocol enrollment to accumulate further clinical evidence. This warrants expedited quality planning of HA-WBRT. Pinnacle 3 Automatic treatment planning was designed to increase planning efficiency while maintaining or improving plan quality and consistency. The aim of the present study is to evaluate the performance of the Pinnacle 3 Auto-Planning on HA-WBRT treatment planning. Ten patients previously treated for brain metastases were selected. Hippocampal volumes were contoured on T1 magnetic resonance (MR) images, and planning target volumes (PTVs) were generated based on RTOG0933. The following 2 types of plans were generated by Pinnacle 3 Auto-Planning: the one with 2 coplanar volumetric modulated arc therapy (VMAT) arcs and the other with 9-field noncoplanar intensity-modulated radiation therapy (IMRT). D 2% and D 98% of PTV were used to calculate homogeneity index (HI). HI and Paddick Conformity index (CI) of PTV as well as D 100% and D max of the hippocampus were used to evaluate the plan quality. All the auto-plans met the dose coverage and constraint objectives based on RTOG0933. The auto-plans eliminated the necessity of generating pseudostructures by the planners, and it required little manual intervention which expedited the planning process. IMRT quality assurance (QA) results also suggest that all the auto-plans are practically acceptable on delivery. Pinnacle 3 Auto-Planning generates acceptable plans by RTOG0933 criteria without time-consuming planning process. The expedited quality planning achieved by

  10. Electron Density Calibration for Radiotherapy Treatment Planning

    International Nuclear Information System (INIS)

    Herrera-Martinez, F.; Rodriguez-Villafuerte, M.; Martinez-Davalos, A.; Ruiz-Trejo, C.; Celis-Lopez, M. A.; Larraga-Gutierrez, J. M.; Garcia-Garduno, A.

    2006-01-01

    Computed tomography (CT) images are used as basic input data for most modern radiosurgery treatment planning systems (TPS). CT data not only provide anatomic information to delineate target volumes, but also allow the introduction of corrections for tissue inhomogeneities into dose calculations during the treatment planning procedure. These corrections involve the determination of a relationship between tissue electron density (ρe) and their corresponding Hounsfield Units (HU). In this work, an elemental analysis of different commercial tissue equivalent materials using Scanning Electron Microscopy was carried out to characterize their chemical composition. The tissue equivalent materials were chosen to ensure a large range of ρe to be included in the CT scanner calibration. A phantom was designed and constructed with these materials to simulate the size of a human head

  11. Oscillator potential for the four-dimensional Hall effect

    International Nuclear Information System (INIS)

    Mardoyan, Levon; Nersessian, Armen

    2005-01-01

    We suggest an exactly solvable model of an oscillator on a four-dimensional sphere interacting with an SU(2) Yang monopole. We show that the properties of the model essentially depend on the monopole charge

  12. 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.

  13. Massive supermultiplets in four-dimensional superstring theory

    International Nuclear Information System (INIS)

    Feng Wanzhe; Lüst, Dieter; Schlotterer, Oliver

    2012-01-01

    We extend the discussion of Feng et al. (2011) on massive Regge excitations on the first mass level of four-dimensional superstring theory. For the lightest massive modes of the open string sector, universal supermultiplets common to all four-dimensional compactifications with N=1,2 and N=4 spacetime supersymmetry are constructed respectively - both their vertex operators and their supersymmetry variations. Massive spinor helicity methods shed light on the interplay between individual polarization states.

  14. A virtual reality solution for evaluation of radiotherapy plans

    DEFF Research Database (Denmark)

    Patel, Daniel; Muren, Ludvig; Mehus, Anfinn

    2007-01-01

    This report presents a VR system for evaluation of treatment plans used in radiotherapy (RT), developed to improve the understanding of the spatial relationships between the patient anatomy and the calculated dose distribution. The VR system offers visualization through interactive volume rendering...... of RT dose distribution and computed tomography (CT) and surface and line rendering of RT structures such as target volumes and organs at risk. The VR system has been installed and networked in a hospital room used for the daily RT conferences, making stereoscopic viewing of treatment planning data...

  15. A virtual reality solution for evaluation of radiotherapy plans

    International Nuclear Information System (INIS)

    Patel, Daniel; Muren, Ludvig Paul; Mehus, Anfinn; Kvinnsland, Yngve; Ulvang, Dag Magne; Villanger, Kare P.

    2007-01-01

    This report presents a VR system for evaluation of treatment plans used in radiotherapy (RT), developed to improve the understanding of the spatial relationships between the patient anatomy and the calculated dose distribution. The VR system offers visualization through interactive volume rendering of RT dose distribution and computed tomography (CT) and surface and line rendering of RT structures such as target volumes and organs at risk. The VR system has been installed and networked in a hospital room used for the daily RT conferences, making stereoscopic viewing of treatment planning data for clinical cases possible

  16. Comparison of Rigid and Adaptive Methods of Propagating Gross Tumor Volume Through Respiratory Phases of Four-Dimensional Computed Tomography Image Data Set

    International Nuclear Information System (INIS)

    Ezhil, Muthuveni; Choi, Bum; Starkschall, George; Bucci, M. Kara; Vedam, Sastry; Balter, Peter

    2008-01-01

    Purpose: To compare three different methods of propagating the gross tumor volume (GTV) through the respiratory phases that constitute a four-dimensional computed tomography image data set. Methods and Materials: Four-dimensional computed tomography data sets of 20 patients who had undergone definitive hypofractionated radiotherapy to the lung were acquired. The GTV regions of interest (ROIs) were manually delineated on each phase of the four-dimensional computed tomography data set. The ROI from the end-expiration phase was propagated to the remaining nine phases of respiration using the following three techniques: (1) rigid-image registration using in-house software, (2) rigid image registration using research software from a commercial radiotherapy planning system vendor, and (3) rigid-image registration followed by deformable adaptation originally intended for organ-at-risk delineation using the same software. The internal GTVs generated from the various propagation methods were compared with the manual internal GTV using the normalized Dice similarity coefficient (DSC) index. Results: The normalized DSC index of 1.01 ± 0.06 (SD) for rigid propagation using the in-house software program was identical to the normalized DSC index of 1.01 ± 0.06 for rigid propagation achieved with the vendor's research software. Adaptive propagation yielded poorer results, with a normalized DSC index of 0.89 ± 0.10 (paired t test, p <0.001). Conclusion: Propagation of the GTV ROIs through the respiratory phases using rigid- body registration is an acceptable method within a 1-mm margin of uncertainty. The adaptive organ-at-risk propagation method was not applicable to propagating GTV ROIs, resulting in an unacceptable reduction of the volume and distortion of the ROIs

  17. Dosimetry audit simulation of treatment planning system in multicenters radiotherapy

    Science.gov (United States)

    Kasmuri, S.; Pawiro, S. A.

    2017-07-01

    Treatment Planning System (TPS) is an important modality that determines radiotherapy outcome. TPS requires input data obtained through commissioning and the potentially error occurred. Error in this stage may result in the systematic error. The aim of this study to verify the TPS dosimetry to know deviation range between calculated and measurement dose. This study used CIRS phantom 002LFC representing the human thorax and simulated all external beam radiotherapy stages. The phantom was scanned using CT Scanner and planned 8 test cases that were similar to those in clinical practice situation were made, tested in four radiotherapy centers. Dose measurement using 0.6 cc ionization chamber. The results of this study showed that generally, deviation of all test cases in four centers was within agreement criteria with average deviation about -0.17±1.59 %, -1.64±1.92 %, 0.34±1.34 % and 0.13±1.81 %. The conclusion of this study was all TPS involved in this study showed good performance. The superposition algorithm showed rather poor performance than either analytic anisotropic algorithm (AAA) and convolution algorithm with average deviation about -1.64±1.92 %, -0.17±1.59 % and -0.27±1.51 % respectively.

  18. Optimization of rotational radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Tulovsky, Vladimir; Ringor, Michael; Papiez, Lech

    1995-01-01

    Purpose: Rotational therapy treatment planning for rotationally symmetric geometry of tumor and healthy tissue provides an important example of testing various approaches to optimizing dose distributions for therapeutic x-ray irradiations. In this article, dose distribution optimization is formulated as a variational problem. This problem is solved analytically and numerically. Methods and Materials: The classical Lagrange method is used to derive equations and inequalities that give necessary conditions for minimizing the mean-square deviation between the ideal dose distribution and the achievable dose distribution. The solution of the resulting integral equation with Cauchy kernel is used to derive analytical formulas for the minimizing irradiation intensity function. Results: The solutions are evaluated numerically and the graphs of the minimizing intensity functions and the corresponding dose distributions are presented. Conclusions: The optimal solutions obtained using the mean-square criterion lead to significant underdosage in some areas of the tumor volume. Possible solutions to this shortcoming are investigated and medically more appropriate criteria for optimization are proposed for future investigations

  19. Ultrasonic and computed tomography in radiotherapy planning - a comparison

    International Nuclear Information System (INIS)

    Schertel, L.

    1980-01-01

    The precondition of any radiotherapy is radiation planning. This must be done individually for every patient and must be applicable for any region of the body. Modern irradiation planning requires pictures of the body parts concerned; these can be made by means of the ultrasonic method and computed tomography. This comparative investigation leads to the result (see fig. 4 and 5) that computed tomographic body part pictures should be preferred to those made sonographically. The opinion of Huenig and Co. [8] that ultrasonic tomography will soon lose some of its importance within irradiation planning once computed tomography is introduced could be confirmed by the latest developments. The authors can confirm this also out of their own experience and agree with Winkel and Hermann [23] that computed tomography cannot be done without any more irradiation planning. (orig.) [de

  20. Multi-objective optimization of inverse planning for accurate radiotherapy

    International Nuclear Information System (INIS)

    Cao Ruifen; Pei Xi; Cheng Mengyun; Li Gui; Hu Liqin; Wu Yican; Jing Jia; Li Guoli

    2011-01-01

    The multi-objective optimization of inverse planning based on the Pareto solution set, according to the multi-objective character of inverse planning in accurate radiotherapy, was studied in this paper. Firstly, the clinical requirements of a treatment plan were transformed into a multi-objective optimization problem with multiple constraints. Then, the fast and elitist multi-objective Non-dominated Sorting Genetic Algorithm (NSGA-II) was introduced to optimize the problem. A clinical example was tested using this method. The results show that an obtained set of non-dominated solutions were uniformly distributed and the corresponding dose distribution of each solution not only approached the expected dose distribution, but also met the dose-volume constraints. It was indicated that the clinical requirements were better satisfied using the method and the planner could select the optimal treatment plan from the non-dominated solution set. (authors)

  1. Performance studies of four-dimensional cone beam computed tomography

    International Nuclear Information System (INIS)

    Qi Zhihua; Chen Guanghong

    2011-01-01

    Four-dimensional cone beam computed tomography (4DCBCT) has been proposed to characterize the breathing motion of tumors before radiotherapy treatment. However, when the acquired cone beam projection data are retrospectively gated into several respiratory phases, the available data to reconstruct each phase is under-sampled and thus causes streaking artifacts in the reconstructed images. To solve the under-sampling problem and improve image quality in 4DCBCT, various methods have been developed. This paper presents performance studies of three different 4DCBCT methods based on different reconstruction algorithms. The aims of this paper are to study (1) the relationship between the accuracy of the extracted motion trajectories and the data acquisition time of a 4DCBCT scan and (2) the relationship between the accuracy of the extracted motion trajectories and the number of phase bins used to sort projection data. These aims will be applied to three different 4DCBCT methods: conventional filtered backprojection reconstruction (FBP), FBP with McKinnon-Bates correction (MB) and prior image constrained compressed sensing (PICCS) reconstruction. A hybrid phantom consisting of realistic chest anatomy and a moving elliptical object with known 3D motion trajectories was constructed by superimposing the analytical projection data of the moving object to the simulated projection data from a chest CT volume dataset. CBCT scans with gantry rotation times from 1 to 4 min were simulated, and the generated projection data were sorted into 5, 10 and 20 phase bins before different methods were used to reconstruct 4D images. The motion trajectories of the moving object were extracted using a fast free-form deformable registration algorithm. The root mean square errors (RMSE) of the extracted motion trajectories were evaluated for all simulated cases to quantitatively study the performance. The results demonstrate (1) longer acquisition times result in more accurate motion delineation

  2. Ongoing development of digital radiotherapy plan review tools

    International Nuclear Information System (INIS)

    Ebert, M.A.; Hatton, J.; Cornes, D.

    2011-01-01

    Full text: To describe ongoing development of software to support the review of radiotherapy treatment planning system (TPS) data. The 'SWAN' software program was conceived in 2000 and initially developed for the RADAR (TROG 03.04) prostate radiotherapy trial. Validation of the SWAN program has been occurring via implementation by TROG in support of multiple clinical trials. Development has continued and the SWAN software program is now supported by modular components which comprise the 'SW AN system'. This provides a comprehensive set of tools for the review, analysis and archive of TPS exports. The SWAN system has now been used in support of over 20 radiotherapy trials and to review the plans of over 2,000 trial participants. The use of the system for the RADAR trial is now culminating in the derivation of dose-outcomes indices for prostate treatment toxicity. Newly developed SWAN tools include enhanced remote data archive/retrieval, display of dose in both relative and absolute modes, and interfacing to a Matlab-based add-on ('VAST') that allows quantitative analysis of delineated volumes including regional overlap statistics for multi-observer studies. Efforts are continuing to develop the SWAN system in the context of international collaboration aimed at harmonising the quality-assurance activities of collaborative trials groups. Tools such as the SWAN system are essential for ensuring the collection of accurate and reliable evidence to guide future radiotherapy treatments. One of the principal challenges of developing such a tool is establishing a development path that will ensure its validity and applicability well into the future.

  3. Use of computed tomography for irradiation planning in practical radiotherapy

    International Nuclear Information System (INIS)

    Riessbeck, K.H.; Achtert, J.; Hegewald, H.

    1985-01-01

    Experience of several years comprising computed tomography into irradiation planning resulted in substantial and organizational arrangements in practical radiotherapy. Precising the individual topography of patient, target volume, and risk organs in the central radiation plane as well as in other planes beeing of interest, permits to optimize the irradiation area. In patients whose radiotherapy requires a complicated field adjustment (for instance head fields, bronchial esophagical cancer) and in all patients who receive an irradiation in motion the irradiation planning is done by the help of CT examination without omitting the localization diagnosis procedure approved. The method of irradiation planning in one plane is represented in which the spatial dimension of target volume can be considered yet after superprojection into the planning plane. However, the topometric gain alone can not result in new irradiation methods. Approved irradiation methods should be modified only in connection with increased knowledge on pathobiology of tumors and on tolerance of healthy tissue with regard to keeping or improving the ratio of curing to complication rate. (author)

  4. Improved Planning Time and Plan Quality Through Multicriteria Optimization for Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Craft, David L.; Hong, Theodore S.; Shih, Helen A.; Bortfeld, Thomas R.

    2012-01-01

    Purpose: To test whether multicriteria optimization (MCO) can reduce treatment planning time and improve plan quality in intensity-modulated radiotherapy (IMRT). Methods and Materials: Ten IMRT patients (5 with glioblastoma and 5 with locally advanced pancreatic cancers) were logged during the standard treatment planning procedure currently in use at Massachusetts General Hospital (MGH). Planning durations and other relevant planning information were recorded. In parallel, the patients were planned using an MCO planning system, and similar planning time data were collected. The patients were treated with the standard plan, but each MCO plan was also approved by the physicians. Plans were then blindly reviewed 3 weeks after planning by the treating physician. Results: In all cases, the treatment planning time was vastly shorter for the MCO planning (average MCO treatment planning time was 12 min; average standard planning time was 135 min). The physician involvement time in the planning process increased from an average of 4.8 min for the standard process to 8.6 min for the MCO process. In all cases, the MCO plan was blindly identified as the superior plan. Conclusions: This provides the first concrete evidence that MCO-based planning is superior in terms of both planning efficiency and dose distribution quality compared with the current trial and error–based IMRT planning approach.

  5. Registration and planning of radiotherapy and proton therapy treatment

    International Nuclear Information System (INIS)

    Bausse, Jerome

    2010-01-01

    Within the frame of an update and renewal project, the Orsay Proton Therapy Centre of the Curie Institute (IPCO) renews its software used for the treatment of patients by proton therapy, a radiotherapy technique which uses proton beams. High energies used in these treatments and the precision provided by proton particle characteristics require a more precise patient positioning than conventional radiotherapy: proton therapy requires a precision of about a millimetre. Thus, markers are placed on the skull which are generally well accepted by patients, but are a problem in the case of paediatric treatment, notably for the youngest children whose skull is still growing. The first objective of this research is thus to use only intrinsic information from X-ray images used when positioning the patient. A second objective is to make the new software (TPS Isogray) perfectly compatible with IPCO requirements by maintaining the strengths of the previous TPS (Treatment Planning System) and being prepared to the implementation of a new installation. After a presentation of the context and state of the art in radiotherapy and patient positioning, the author proposes an overview of 2D registration methods, presents a new method for 2x2D registration, and addresses the problem of 3D registration. Then, after a presentation of proton therapy, the author addresses different specific issues and aspects: the compensator (simulation, calculation, and tests), dose calculation, the 'Pencil-Beam' algorithm, tests, and introduced improvements [fr

  6. Model-based image reconstruction for four-dimensional PET

    International Nuclear Information System (INIS)

    Li Tianfang; Thorndyke, Brian; Schreibmann, Eduard; Yang Yong; Xing Lei

    2006-01-01

    Positron emission tonography (PET) is useful in diagnosis and radiation treatment planning for a variety of cancers. For patients with cancers in thoracic or upper abdominal region, the respiratory motion produces large distortions in the tumor shape and size, affecting the accuracy in both diagnosis and treatment. Four-dimensional (4D) (gated) PET aims to reduce the motion artifacts and to provide accurate measurement of the tumor volume and the tracer concentration. A major issue in 4D PET is the lack of statistics. Since the collected photons are divided into several frames in the 4D PET scan, the quality of each reconstructed frame degrades as the number of frames increases. The increased noise in each frame heavily degrades the quantitative accuracy of the PET imaging. In this work, we propose a method to enhance the performance of 4D PET by developing a new technique of 4D PET reconstruction with incorporation of an organ motion model derived from 4D-CT images. The method is based on the well-known maximum-likelihood expectation-maximization (ML-EM) algorithm. During the processes of forward- and backward-projection in the ML-EM iterations, all projection data acquired at different phases are combined together to update the emission map with the aid of deformable model, the statistics is therefore greatly improved. The proposed algorithm was first evaluated with computer simulations using a mathematical dynamic phantom. Experiment with a moving physical phantom was then carried out to demonstrate the accuracy of the proposed method and the increase of signal-to-noise ratio over three-dimensional PET. Finally, the 4D PET reconstruction was applied to a patient case

  7. Four-dimensional hilbert curves for R-trees

    DEFF Research Database (Denmark)

    Haverkort, Herman; Walderveen, Freek van

    2011-01-01

    Two-dimensional R-trees are a class of spatial index structures in which objects are arranged to enable fast window queries: report all objects that intersect a given query window. One of the most successful methods of arranging the objects in the index structure is based on sorting the objects...... according to the positions of their centers along a two-dimensional Hilbert space-filling curve. Alternatively, one may use the coordinates of the objects' bounding boxes to represent each object by a four-dimensional point, and sort these points along a four-dimensional Hilbert-type curve. In experiments...

  8. Knowledge-based computer systems for radiotherapy planning.

    Science.gov (United States)

    Kalet, I J; Paluszynski, W

    1990-08-01

    Radiation therapy is one of the first areas of clinical medicine to utilize computers in support of routine clinical decision making. The role of the computer has evolved from simple dose calculations to elaborate interactive graphic three-dimensional simulations. These simulations can combine external irradiation from megavoltage photons, electrons, and particle beams with interstitial and intracavitary sources. With the flexibility and power of modern radiotherapy equipment and the ability of computer programs that simulate anything the machinery can do, we now face a challenge to utilize this capability to design more effective radiation treatments. How can we manage the increased complexity of sophisticated treatment planning? A promising approach will be to use artificial intelligence techniques to systematize our present knowledge about design of treatment plans, and to provide a framework for developing new treatment strategies. Far from replacing the physician, physicist, or dosimetrist, artificial intelligence-based software tools can assist the treatment planning team in producing more powerful and effective treatment plans. Research in progress using knowledge-based (AI) programming in treatment planning already has indicated the usefulness of such concepts as rule-based reasoning, hierarchical organization of knowledge, and reasoning from prototypes. Problems to be solved include how to handle continuously varying parameters and how to evaluate plans in order to direct improvements.

  9. A Monte Carlo dose calculation tool for radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Ma, C.-M.; Li, J.S.; Pawlicki, T.; Jiang, S.B.; Deng, J.; Lee, M.C.; Koumrian, T.; Luxton, M.; Brain, S.

    2002-01-01

    A Monte Carlo user code, MCDOSE, has been developed for radiotherapy treatment planning (RTP) dose calculations. MCDOSE is designed as a dose calculation module suitable for adaptation to host RTP systems. MCDOSE can be used for both conventional photon/electron beam calculation and intensity modulated radiotherapy (IMRT) treatment planning. MCDOSE uses a multiple-source model to reconstruct the treatment beam phase space. Based on Monte Carlo simulated or measured beam data acquired during commissioning, source-model parameters are adjusted through an automated procedure. Beam modifiers such as jaws, physical and dynamic wedges, compensators, blocks, electron cut-outs and bolus are simulated by MCDOSE together with a 3D rectilinear patient geometry model built from CT data. Dose distributions calculated using MCDOSE agreed well with those calculated by the EGS4/DOSXYZ code using different beam set-ups and beam modifiers. Heterogeneity correction factors for layered-lung or layered-bone phantoms as calculated by both codes were consistent with measured data to within 1%. The effect of energy cut-offs for particle transport was investigated. Variance reduction techniques were implemented in MCDOSE to achieve a speedup factor of 10-30 compared to DOSXYZ. (author)

  10. 3-Dimentional radiotherapy versus conventional treatment plans for gastric cancer

    Directory of Open Access Journals (Sweden)

    Aghili M

    2010-11-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: The current standard of adjuvant management for gastric cancer after curative resection based on the results of intergroup 0116 is concurrent chemoradiation. Current guidelines for designing these challenging fields still include two-dimensional simulation with simple AP-PA parallel opposed design. However, the implementation of radiotherapy (RT remains a concern. Our objective was to compare three-dimensional (3D techniques to the more commonly used AP-PA technique."n"nMethods: A total of 24 patients with stages II-IV adenocarcinoma of the stomach were treated with adjuvant postoperative chemoradiation with simple AP-PA technique, using Cobalt-60. Total radiation dose was 50.4Gy. Landmark-based fields were simulated to assess PTV coverage. For each patient, three additional radiotherapy treatment plans were generated using three-dimensional (3D technique. The four treatment plans were then compared for target volume coverage and dose to normal tissues (liver, spinal cord, kidneys using dose volume histogram (DVH analysis."n"nResults: The three-dimensional planning techniques provided 10% superior PTV coverage compared to conventional AP-PA fields (p<0.001. Comparative DVHs for the right kidney, left kidney

  11. Lattice classification of the four-dimensional heterotic strings

    International Nuclear Information System (INIS)

    Balog, J.; Forgacs, P.; Vecsernyes, P.; Horvath, Z.

    1987-06-01

    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)

  12. The scalar curvature problem on the four dimensional half sphere

    CERN Document Server

    Ben-Ayed, M; El-Mehdi, K

    2003-01-01

    In this paper, we consider the problem of prescribing the scalar curvature under minimal boundary conditions on the standard four dimensional half sphere. We provide an Euler-Hopf type criterion for a given function to be a scalar curvature for some metric conformal to the standard one. Our proof involves the study of critical points at infinity of the associated variational problem.

  13. Statistical Entropy of Four-Dimensional Extremal Black Holes

    International Nuclear Information System (INIS)

    Maldacena, J.M.; Strominger, A.

    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. copyright 1996 The American Physical Society

  14. Four-dimensional conversion for spiritual leadership development: A ...

    African Journals Online (AJOL)

    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.

  15. Variability of four-dimensional computed tomography patient models

    NARCIS (Netherlands)

    Sonke, Jan-Jakob; Lebesque, Joos; van Herk, Marcel

    2008-01-01

    PURPOSE: To quantify the interfractional variability in lung tumor trajectory and mean position during the course of radiation therapy. METHODS AND MATERIALS: Repeat four-dimensional (4D) cone-beam computed tomography (CBCT) scans (median, nine scans/patient) routinely acquired during the course of

  16. Conformal three dimensional radiotherapy treatment planning in Lund

    Energy Technology Data Exchange (ETDEWEB)

    Knoos, T; Nilsson, P [Lund Univ. (Sweden). Dept. of Radiation Physics; Anders, A [Lund Univ. (Sweden). Dept. of Oncology

    1995-12-01

    The use of conformal therapy is based on 3-dimensional treatment planning as well as on methods and routines for 3-dimensional patient mapping, 3-dimensional virtual simulation and others. The management of patients at the Radiotherapy Department at the University Hospital in Lund (Sweden) is discussed. About 2100 new patients are annually treated with external radiotherapy using seven linear accelerators. Three of the accelerators have dual photon energies and electron treatment facilities. A multi-leaf collimator as well as an electronic portal imaging device are available on one machine. Two simulators and an in-house CT-scanner are used for treatment planning. From 1988 to 1992 Scandiplan (Umplan) was used. Since 1992, the treatment planning system is TMS (HELAX AB, Sweden), which is based on the pencil beam algorithm of Ahnesjo. The calculations use patient modulated accelerator specific energy fluence spectra which are compiled with pencil beams from Monte Carlo generated energy absorption kernels. Heterogeneity corrections are performed with results close to conventional algorithms. Irregular fields, either from standard or individual blocks and from multi-leaf collimators are handled by the treatment planning system. The field shape is determined conveniently using the beam`s eye view. The final field shape is exported electronically to either the block cutting machine or the multileaf collimator control computer. All patient fields are checked against the beam`s eye view during simulation using manual methods. Treatment verification is performed by portal films and in vivo dosimetry with silicon diodes or TL-dosimetry. Up to now, approximately 4400 patients have received a highly individualized 3-dimensional conformal treatment.

  17. Conformal three dimensional radiotherapy treatment planning in Lund

    International Nuclear Information System (INIS)

    Knoos, T.; Nilsson, P.; Anders, A.

    1995-01-01

    The use of conformal therapy is based on 3-dimensional treatment planning as well as on methods and routines for 3-dimensional patient mapping, 3-dimensional virtual simulation and others. The management of patients at the Radiotherapy Department at the University Hospital in Lund (Sweden) is discussed. About 2100 new patients are annually treated with external radiotherapy using seven linear accelerators. Three of the accelerators have dual photon energies and electron treatment facilities. A multi-leaf collimator as well as an electronic portal imaging device are available on one machine. Two simulators and an in-house CT-scanner are used for treatment planning. From 1988 to 1992 Scandiplan (Umplan) was used. Since 1992, the treatment planning system is TMS (HELAX AB, Sweden), which is based on the pencil beam algorithm of Ahnesjo. The calculations use patient modulated accelerator specific energy fluence spectra which are compiled with pencil beams from Monte Carlo generated energy absorption kernels. Heterogeneity corrections are performed with results close to conventional algorithms. Irregular fields, either from standard or individual blocks and from multi-leaf collimators are handled by the treatment planning system. The field shape is determined conveniently using the beam's eye view. The final field shape is exported electronically to either the block cutting machine or the multileaf collimator control computer. All patient fields are checked against the beam's eye view during simulation using manual methods. Treatment verification is performed by portal films and in vivo dosimetry with silicon diodes or TL-dosimetry. Up to now, approximately 4400 patients have received a highly individualized 3-dimensional conformal treatment

  18. Use of Maximum Intensity Projections (MIPs) for target outlining in 4DCT radiotherapy planning.

    Science.gov (United States)

    Muirhead, Rebecca; McNee, Stuart G; Featherstone, Carrie; Moore, Karen; Muscat, Sarah

    2008-12-01

    Four-dimensional computed tomography (4DCT) is currently being introduced to radiotherapy centers worldwide, for use in radical radiotherapy planning for non-small cell lung cancer (NSCLC). A significant drawback is the time required to delineate 10 individual CT scans for each patient. Every department will hence ask the question if the single Maximum Intensity Projection (MIP) scan can be used as an alternative. Although the problems regarding the use of the MIP in node-positive disease have been discussed in the literature, a comprehensive study assessing its use has not been published. We compared an internal target volume (ITV) created using the MIP to an ITV created from the composite volume of 10 clinical target volumes (CTVs) delineated on the 10 phases of the 4DCT. 4DCT data was collected from 14 patients with NSCLC. In each patient, the ITV was delineated on the MIP image (ITV_MIP) and a composite ITV created from the 10 CTVs delineated on each of the 10 scans in the dataset. The structures were compared by assessment of volumes of overlap and exclusion. There was a median of 19.0% (range, 5.5-35.4%) of the volume of ITV_10phase not enclosed by the ITV_MIP, demonstrating that the use of the MIP could result in under-treatment of disease. In contrast only a very small amount of the ITV_MIP was not enclosed by the ITV_10phase (median of 2.3%, range, 0.4-9.8%), indicating the ITV_10phase covers almost all of the tumor tissue as identified by MIP. Although there were only two Stage I patients, both demonstrated very similar ITV_10phase and ITV_MIP volumes. These findings suggest that Stage I NSCLC tumors could be outlined on the MIP alone. In Stage II and III tumors the ITV_10phase would be more reliable. To prevent under-treatment of disease, the MIP image can only be used for delineation in Stage I tumors.

  19. Spatiotemporal radiotherapy planning using a global optimization approach

    Science.gov (United States)

    Adibi, Ali; Salari, Ehsan

    2018-02-01

    This paper aims at quantifying the extent of potential therapeutic gain, measured using biologically effective dose (BED), that can be achieved by altering the radiation dose distribution over treatment sessions in fractionated radiotherapy. To that end, a spatiotemporally integrated planning approach is developed, where the spatial and temporal dose modulations are optimized simultaneously. The concept of equivalent uniform BED (EUBED) is used to quantify and compare the clinical quality of spatiotemporally heterogeneous dose distributions in target and critical structures. This gives rise to a large-scale non-convex treatment-plan optimization problem, which is solved using global optimization techniques. The proposed spatiotemporal planning approach is tested on two stylized cancer cases resembling two different tumor sites and sensitivity analysis is performed for radio-biological and EUBED parameters. Numerical results validate that spatiotemporal plans are capable of delivering a larger BED to the target volume without increasing the BED in critical structures compared to conventional time-invariant plans. In particular, this additional gain is attributed to the irradiation of different regions of the target volume at different treatment sessions. Additionally, the trade-off between the potential therapeutic gain and the number of distinct dose distributions is quantified, which suggests a diminishing marginal gain as the number of dose distributions increases.

  20. Chest wall desmoid tumours treated with definitive radiotherapy: a plan comparison of 3D conformal radiotherapy, intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy

    International Nuclear Information System (INIS)

    Liu, Jia; Ng, Diana; Lee, James; Stalley, Paul; Hong, Angela

    2016-01-01

    Definitive radiotherapy is often used for chest wall desmoid tumours due to size or anatomical location. The delivery of radiotherapy is challenging due to the large size and constraints of normal surrounding structures. We compared the dosimetry of 3D conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc radiotherapy (VMAT) to evaluate the best treatment option. Ten consecutive patients with inoperable chest wall desmoid tumours (PTV range 416–4549 cm 3 ) were selected. For each patient, 3DCRT, IMRT and VMAT plans were generated and the Conformity Index (CI), organ at risk (OAR) doses and monitor unit (MU) were evaluated. The Wilcoxon signed-rank test was used to compare dose delivered to both target and OARs. The mean number of fields for 3DCRT and IMRT were 6.3 ± 2.1, 7.2 ± 1.8. The mean number of arcs for VMAT was 3.7 ± 1.1. The mean conformity index of VMAT (0.98 ± 0.14) was similar to that of IMRT (1.03 ± 0.13), both of which were significantly better than 3DCRT (1.35 ± 0.20; p = 0.005). The mean dose to lung was significantly higher for 3DCRT (11.9Gy ± 7.9) compared to IMRT (9.4Gy ± 5.4, p = 0.014) and VMAT (8.9Gy ± 4.5, p = 0.017). For the 3 females, the low dose regions in the ipsilateral breast for VMAT were generally less with VMAT. IMRT plans required 1427 ± 532 MU per fraction which was almost 4-fold higher than 3DCRT (313 ± 112, P = 0.005). Compared to IMRT, VMAT plans required 60 % less MU (570 ± 285, P = 0.005). For inoperable chest wall desmoid tumours, VMAT delivered equivalent target coverage when compared to IMRT but required 60 % less MU. Both VMAT and IMRT were superior to 3DCRT in terms of better PTV coverage and sparing of lung tissue

  1. "SABER": A new software tool for radiotherapy treatment plan evaluation.

    Science.gov (United States)

    Zhao, Bo; Joiner, Michael C; Orton, Colin G; Burmeister, Jay

    2010-11-01

    Both spatial and biological information are necessary in order to perform true optimization of a treatment plan and for predicting clinical outcome. The goal of this work is to develop an enhanced treatment plan evaluation tool which incorporates biological parameters and retains spatial dose information. A software system is developed which provides biological plan evaluation with a novel combination of features. It incorporates hyper-radiosensitivity using the induced-repair model and applies the new concept of dose convolution filter (DCF) to simulate dose wash-out effects due to cell migration, bystander effect, and/or tissue motion during treatment. Further, the concept of spatial DVH (sDVH) is introduced to evaluate and potentially optimize the spatial dose distribution in the target volume. Finally, generalized equivalent uniform dose is derived from both the physical dose distribution (gEUD) and the distribution of equivalent dose in 2 Gy fractions (gEUD2) and the software provides three separate models for calculation of tumor control probability (TCP), normal tissue complication probability (NTCP), and probability of uncomplicated tumor control (P+). TCP, NTCP, and P+ are provided as a function of prescribed dose and multivariable TCP, NTCP, and P+ plots are provided to illustrate the dependence on individual parameters used to calculate these quantities. Ten plans from two clinical treatment sites are selected to test the three calculation models provided by this software. By retaining both spatial and biological information about the dose distribution, the software is able to distinguish features of radiotherapy treatment plans not discernible using commercial systems. Plans that have similar DVHs may have different spatial and biological characteristics and the application of novel tools such as sDVH and DCF within the software may substantially change the apparent plan quality or predicted plan metrics such as TCP and NTCP. For the cases examined

  2. Specification and acceptance testing of radiotherapy treatment planning systems

    International Nuclear Information System (INIS)

    2007-04-01

    Quality assurance (QA) in the radiation therapy treatment planning process is essential to ensure accurate dose delivery to the patient and to minimize the possibility of accidental exposure. The computerized radiotherapy treatment planning systems (RTPSs) are now widely available in industrialized and developing countries and it is of special importance to support hospitals in Member States in developing procedures for acceptance testing, commissioning and QA of their RTPSs. Responding to these needs, a group of experts developed an IAEA publication with such recommendations, which was published in 2004 as IAEA Technical Reports Series No. 430. This report provides a general framework and describes a large number of tests and procedures that should be considered by the users of new RTPSs. However, small hospitals with limited resources or large hospitals with high patient load and limited staff are not always able to perform complete characterization, validation and software testing of algorithms used in RTPSs. Therefore, the IAEA proposed more specific guidelines that provide a step-by-step recommendation for users at hospitals or cancer centres how to implement acceptance and commissioning procedures for newly purchased RTPSs. The current publication was developed in the framework of the Coordinated Research Project on Development of Procedures for Quality Assurance for Dosimetry Calculations in Radiotherapy and uses the International Electrotechnical Commission (IEC) standard IEC 62083, Requirements for the Safety of Radiotherapy Treatment Planning Systems as its basis. The report addresses the procedures for specification and acceptance testing of RTPSs to be used by both manufacturers and users at the hospitals. Recommendations are provided for specific tests to be performed at the manufacturing facility known as type tests, and for acceptance tests to be performed at the hospital known as site tests. The purpose of acceptance testing is to demonstrate to the

  3. Comparison of RapidArc plans and fixed field intensity modulated radiotherapy planning in cervical cancer radiotherapy

    International Nuclear Information System (INIS)

    Liu Xiangyu; Liu Xianfeng; He Ya'nan; Yin Wenjuan; Wu Yongzhong

    2011-01-01

    Objective: To explore the advantages and disadvantages between the RapidArc plans and fixed-field IMRT plan (IMRT). Methods: Ten cases of cervical cancer,aged 55 (36-70), who were to receive post-operative radiotherapy were selected randomly. Single arc (Arc 1), two arcs (Arc 2), and three arc (Arc 3) RapidArc plans and fixed-field IMRT plan were designed respectively in the Eclipse 8.6 planning system. The designing, treatment time, target area, and dose distribution of organs at risk by these 4 planning techniques were compared. Results: The values of average planned treatment time by the Arc 1, Arc 2, and Arc 3 ten cases was 98, 155, 185, and 46 min, respectively. The values of average treatment time in the Varian IX accelerator were 2.15, 3.32, 4.48, and 6.95 min, respectively. The average mean doses were (48.99±1.08),(49.40±0.51), (49.51±0.62), and (48.65±0.92) Gy, respectively. The values of homogeneity index (HI) of target were 1.11±0.07, 1.07±0.02, 1.06±0.02, and 1.12±0.05, respectively. The values of conformal index (CI) of target were 0.73±0.13, 0.87±0.06, 0.87±0.06, and 0.79±0.06, respectively. The doses at rectum, bladder, and small intestine calculated by IMRT plan were the lowest, and the doses at the femoral neck calculated by these 4 plans were similar. Conclusions: The RapidArc plan is superior in dose distribution at target, HI, CI, and treatment time to IMRT, but IMRT plan is superior to RapidArc in planned dose calculation time and protection of organs at risk. However, in general, the RapidArc plan is better in clinical application than IMRT plan. (authors)

  4. Identification of Architectural Functions in A Four-Dimensional Space

    Directory of Open Access Journals (Sweden)

    Firza Utama

    2012-06-01

    Full Text Available This research has explored the possibilities and concept of architectural space in a virtual environment. The virtual environment exists as a different concept, and challenges the constraints of the physical world. One of the possibilities in a virtual environment is that it is able to extend the spatial dimension higher than the physical three-dimension. To take the advantage of this possibility, this research has applied some geometrical four-dimensional (4D methods to define virtual architectural space. The spatial characteristics of 4D space is established by analyzing the four-dimensional structure that can be comprehended by human participant for its spatial quality, and by developing a system to control the fourth axis of movement. Multiple three-dimensional spaces that fluidly change their volume have been defined as one of the possibilities of virtual architecturalspace concept in order to enrich our understanding of virtual spatial experience.

  5. Common time in a four-dimensional symmetry framework

    International Nuclear Information System (INIS)

    Hsu, J.P.; Sherry, T.N.

    1980-01-01

    Following the ideas of Poincare, Reichenbach, and Grunbaum concerning the convention of setting up clock systems, we analyze clock systems and light propagation within the framework of four-dimensional symmetry. It is possible to construct a new four-dimensional symmetry framework incorporating common time: observers in different inertial frames of reference use one and the same clock system, which is located in any one of the frames. Consequently, simultaneity has a meaning independent of position and independent of frame of reference. A further consequence is that the two-way speeds of light alone are isotropic in any frame. By the choice of clock system there will be one frame in which the one-way speed of light is isotropic. This frame can be arbitrarily chosen. The difference between one-way speeds an two-way speeds of light signals is considered in detail

  6. Supergravity duals of supersymmetric four dimensional gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Bigazzi, F [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Cotrone, A L [Centre de Physique Theorique, Ecole Polytechnique, Palaiseau Cedex (France); [INFN, Rome (Italy); Petrini, M [Centre de Physique Theorique, Ecole Polytechnique, Palaiseau (France); Zaffaroni, A [Universita di Milano-Bicocca and INFN, Milan (Italy)

    2002-03-01

    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)

  7. Four dimensional sigma model coupled to the metric tensor field

    International Nuclear Information System (INIS)

    Ghika, G.; Visinescu, M.

    1980-02-01

    We discuss the four dimensional nonlinear sigma model with an internal O(n) invariance coupled to the metric tensor field satisfying Einstein equations. We derive a bound on the coupling constant between the sigma field and the metric tensor using the theory of harmonic maps. A special attention is paid to Einstein spaces and some new explicit solutions of the model are constructed. (author)

  8. Comparison of DVH data from multiple radiotherapy treatment planning systems

    International Nuclear Information System (INIS)

    Ebert, M A; Kearvell, R; Hooton, B; Spry, N A; Bydder, S A; Joseph, D J; Haworth, A; Hug, B

    2010-01-01

    This study examined the variation of dose-volume histogram (DVH) data sourced from multiple radiotherapy treatment planning systems (TPSs). Treatment plan exports were obtained from 33 Australian and New Zealand centres during a dosimetry study. Plan information, including DVH data, was exported from the TPS at each centre and reviewed in a digital review system (SWAN). The review system was then used to produce an independent calculation of DVH information for each delineated structure. The relationships between DVHs extracted from each TPS and independently calculated were examined, particularly in terms of the influence of CT scan slice and pixel widths, the resolution of dose calculation grids and the TPS manufacturer. Calculation of total volume and DVH data was consistent between SWAN and each TPS, with the small discrepancies found tending to increase with decreasing structure size. This was significantly influenced by the TPS model used to derive the data. For target structures covered with relatively uniform dose distributions, there was a significant difference between the minimum dose in each TPS-exported DVH and that calculated independently. (note)

  9. Inverse planning of energy-modulated electron beams in radiotherapy

    International Nuclear Information System (INIS)

    Gentry, John R.; Steeves, Richard; Paliwal, Bhudatt A.

    2006-01-01

    The use of megavoltage electron beams often poses a clinical challenge in that the planning target volume (PTV) is anterior to other radiosensitive structures and has variable depth. To ensure that skin as well as the deepest extent of the PTV receives the prescribed dose entails prescribing to a point beyond the depth of peak dose for a single electron energy. This causes dose inhomogeneities and heightened potential for tissue fibrosis, scarring, and possible soft tissue necrosis. Use of bolus on the skin improves the entrant dose at the cost of decreasing the therapeutic depth that can be treated. Selection of a higher energy to improve dose homogeneity results in increased dose to structures beyond the PTV, as well as enlargement of the volume receiving heightened dose. Measured electron data from a linear accelerator was used as input to create an inverse planning tool employing energy and intensity modulation using bolus (e-IMRT TM ). Using tools readily available in a radiotherapy department, the applications of energy and intensity modulation on the central axis makes it possible to remove hot spots of 115% or more over the depths clinically encountered. The e-IMRT TM algorithm enables the development of patient-specific dose distributions with user-defined positions of peak dose, range, and reduced dose to points beyond the prescription point

  10. [Automatic Extraction and Analysis of Dosimetry Data in Radiotherapy Plans].

    Science.gov (United States)

    Song, Wei; Zhao, Di; Lu, Hong; Zhang, Biyun; Ma, Jun; Yu, Dahai

    To improve the efficiency and accuracy of extraction and analysis of dosimetry data in radiotherapy plans for a batch of patients. With the interface function provided in Matlab platform, a program was written to extract the dosimetry data exported from treatment planning system in DICOM RT format and exported the dose-volume data to an Excel file with the SPSS compatible format. This method was compared with manual operation for 14 gastric carcinoma patients to validate the efficiency and accuracy. The output Excel data were compatible with SPSS in format, the dosimetry data error for PTV dose interval of 90%-98%, PTV dose interval of 99%-106% and all OARs were -3.48E-5 ± 3.01E-5, -1.11E-3 ± 7.68E-4, -7.85E-5 ± 9.91E-5 respectively. Compared with manual operation, the time required was reduced from 5.3 h to 0.19 h and input error was reduced from 0.002 to 0. The automatic extraction of dosimetry data in DICOM RT format for batch patients, the SPSS compatible data exportation, quick analysis were achieved in this paper. The efficiency of clinical researches based on dosimetry data analysis of large number of patients will be improved with this methods.

  11. Considerations of MCNP Monte Carlo code to be used as a radiotherapy treatment planning tool.

    Science.gov (United States)

    Juste, B; Miro, R; Gallardo, S; Verdu, G; Santos, A

    2005-01-01

    The present work has simulated the photon and electron transport in a Theratron 780® (MDS Nordion)60Co radiotherapy unit, using the Monte Carlo transport code, MCNP (Monte Carlo N-Particle). This project explains mainly the different methodologies carried out to speedup calculations in order to apply this code efficiently in radiotherapy treatment planning.

  12. Challenges of radiotherapy: report on the 4D treatment planning workshop 2013

    NARCIS (Netherlands)

    Knopf, Antje; Nill, Simeon; Yohannes, Indra; Graeff, Christian; Dowdell, Stephen; Kurz, Christopher; Sonke, Jan-Jakob; Biegun, Aleksandra K; Lang, Stephanie; McClelland, Jamie R.; Champion, Benjamin; Fast, Martin; Wölfelschneider, Jens; Gianoli, Chiara; Rucinski, Antoni; Baroni, Guido; Richter, Christian; van de Water, Steven; Grassberger, Clemens; Weber, Damien; Poulsen, Per; Shimizu, Shinichi; Bert, Christoph

    2014-01-01

    This report, compiled by experts on the treatment of mobile targets with advanced radiotherapy, summarizes the main conclusions and innovations achieved during the 4D treatment planning workshop 2013. This annual workshop focuses on research aiming to advance 4D radiotherapy treatments, including

  13. Radiotherapy

    International Nuclear Information System (INIS)

    Prosnitz, L.R.; Kapp, D.S.; Weissberg, J.B.

    1983-01-01

    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

  14. Spinors and supersymmetry in four-dimensional Euclidean space

    International Nuclear Information System (INIS)

    McKeon, D.G.C.; Sherry, T.N.

    2001-01-01

    Spinors in four-dimensional Euclidean space are treated using the decomposition of the Euclidean space SO(4) symmetry group into SU(2)xSU(2). Both 2- and 4-spinor representations of this SO(4) symmetry group are shown to differ significantly from the corresponding spinor representations of the SO(3, 1) symmetry group in Minkowski space. The simplest self conjugate supersymmetry algebra allowed in four-dimensional Euclidean space is demonstrated to be an N=2 supersymmetry algebra which resembles the N=2 supersymmetry algebra in four-dimensional Minkowski space. The differences between the two supersymmetry algebras gives rise to different representations; in particular an analysis of the Clifford algebra structure shows that the momentum invariant is bounded above by the central charges in 4dE, while in 4dM the central charges bound the momentum invariant from below. Dimensional reduction of the N=1 SUSY algebra in six-dimensional Minkowski space (6dM) to 4dE reproduces our SUSY algebra in 4dE. This dimensional reduction can be used to introduce additional generators into the SUSY algebra in 4dE. Well known interpolating maps are used to relate the N=2 SUSY algebra in 4dE derived in this paper to the N=2 SUSY algebra in 4dM. The nature of the spinors in 4dE allows us to write an axially gauge invariant model which is shown to be both Hermitian and anomaly-free. No equivalent model exists in 4dM. Useful formulae in 4dE are collected together in two appendixes

  15. On 'Common time' in the four-dimensional symmetry framework

    International Nuclear Information System (INIS)

    Gulati, Shobha

    1980-01-01

    Recently Hsu has advanced a 'Four-Dimensional Symmetry Theory' with a 'Common time' for all inertial frames. He believes that such a 'Common time' is physically possible. However, as a consequence of 'Common time', Hsu asserts that the speed of light in some inertial frames is not necessarily invariant and isotropic - a result, quite contrary to Einstein's Principle of the constancy of the velocity of light. In the present paper, taking Hsu's 'Common time' at its face value, the author has demonstrated that his formulation itself leads to physically absurd results. A 'Common time' for all inertial frames is just not possible. (author)

  16. Naked singularities in four-dimensional string backgrounds

    International Nuclear Information System (INIS)

    Mohammedi, N.

    1993-04-01

    It is shown that gauged nonlinear sigma models can be always deformed by terms proportional to the field strength of the gauge fields (nonminimal gauging). These deformations can be interpreted as perturbations, by marginal operators, of conformal coset models. When applied to the SL(2, R)xSU(2)/U(1)xU(1)) WZWN model, a large class of four-dimensional curved spacetime backgrounds are obtained. In particular, a naked singularity may form at a time when the volume of the universe is different from zero. (orig.)

  17. Quantum walk with a four-dimensional coin

    International Nuclear Information System (INIS)

    Hamilton, Craig S; Gabris, Aurel; Jex, Igor; Barnett, Stephen M

    2011-01-01

    We examine the physical implementation of a discrete time quantum walk with a four-dimensional coin. Our quantum walker is a photon moving repeatedly through a time delay loop, with time being our position space. The quantum coin is implemented using the internal states of the photon: the polarization and two of the orbital angular momentum states. We demonstrate how to implement this physically and what components would be needed. We then illustrate some of the results that could be obtained by performing the experiment.

  18. Four-dimensional optical manipulation of colloidal particles

    DEFF Research Database (Denmark)

    Rodrigo, P.J.; Daria, V.R.; Glückstad, J.

    2005-01-01

    We transform a TEM00 laser mode into multiple counterpropagating optical traps to achieve four-dimensional simultaneous manipulation of multiple particles. Efficient synthesis and dynamic control of the counterpropagating-beam traps is carried out via the generalized phase contrast method......, and a spatial polarization-encoding scheme. Our experiments genuinely demonstrate real-time, interactive particle-position control for forming arbitrary volumetric constellations and complex three-dimensional trajectories of multiple particles. This opens up doors for cross-disciplinary cutting-edge research...

  19. Safety Improvement in Radiotherapy Treatment Plan. Planning vs Redundant Check vs in vivo Dosimetry

    International Nuclear Information System (INIS)

    Torres Diaz, J.; Ascencion Ybarra, Y.; La Fuentes Rosales, L. de; Lara Mas, E.; Larrinaga Cortinas, E.

    2013-01-01

    In Cuba it is mandatory to have an independent monitor units check before any radiotherapy treatment is started. The main objective of this paper is to enhance the safety of the radiotherapy planning by developing and testing a practical tool to double check the monitor units calculation for external beam high energy photon therapy. A software for monitor units (MUs) verification was designed and coded. It considers the common in clinical practice isocentric set-ups. The in vivo dosimetry measurements were done with a silicon diode system for 6 MV photon beams to support the validation of the software. The results show a discrepancy within 5% between the 3 methods which is in accordance with international recommendations. (Author)

  20. Four-dimensional maps of the human somatosensory system.

    Science.gov (United States)

    Avanzini, Pietro; Abdollahi, Rouhollah O; Sartori, Ivana; Caruana, Fausto; Pelliccia, Veronica; Casaceli, Giuseppe; Mai, Roberto; Lo Russo, Giorgio; Rizzolatti, Giacomo; Orban, Guy A

    2016-03-29

    A fine-grained description of the spatiotemporal dynamics of human brain activity is a major goal of neuroscientific research. Limitations in spatial and temporal resolution of available noninvasive recording and imaging techniques have hindered so far the acquisition of precise, comprehensive four-dimensional maps of human neural activity. The present study combines anatomical and functional data from intracerebral recordings of nearly 100 patients, to generate highly resolved four-dimensional maps of human cortical processing of nonpainful somatosensory stimuli. These maps indicate that the human somatosensory system devoted to the hand encompasses a widespread network covering more than 10% of the cortical surface of both hemispheres. This network includes phasic components, centered on primary somatosensory cortex and neighboring motor, premotor, and inferior parietal regions, and tonic components, centered on opercular and insular areas, and involving human parietal rostroventral area and ventral medial-superior-temporal area. The technique described opens new avenues for investigating the neural basis of all levels of cortical processing in humans.

  1. Estimation of four-dimensional dose distribution using electronic portal imaging device in radiation therapy

    International Nuclear Information System (INIS)

    Mizoguchi, Asumi; Arimura, Hidetaka; Shioyama, Yoshiyuki

    2013-01-01

    We are developing a method to evaluate four-dimensional radiation dose distribution in a patient body based upon the animated image of EPID (electronic portal imaging device) which is an image of beam-direction at the irradiation. In the first place, we have obtained the image of the dose which is emitted from patient body at therapy planning using therapy planning CT image and dose evaluation algorism. In the second place, we have estimated the emission dose image at the irradiation using EPID animated image which is obtained at the irradiation. In the third place, we have got an affine transformation matrix including respiratory movement in the body by performing linear registration on the emission dose image at therapy planning to get the one at the irradiation. In the fourth place, we have applied the affine transformation matrix on the therapy planning CT image and estimated the CT image 'at irradiation'. Finally we have evaluated four-dimensional dose distribution by calculating dose distribution in the CT image 'at irradiation' which has been estimated for each frame of the EPID animated-image. This scheme may be useful for evaluating therapy results and risk management. (author)

  2. Validation of Fully Automated VMAT Plan Generation for Library-Based Plan-of-the-Day Cervical Cancer Radiotherapy

    OpenAIRE

    Sharfo, Abdul Wahab M.; Breedveld, Sebastiaan; Voet, Peter W. J.; Heijkoop, Sabrina T.; Mens, Jan-Willem M.; Hoogeman, Mischa S.; Heijmen, Ben J. M.

    2016-01-01

    textabstractPurpose: To develop and validate fully automated generation of VMAT plan-libraries for plan-of-the-day adaptive radiotherapy in locally-advanced cervical cancer. Material and Methods: Our framework for fully automated treatment plan generation (Erasmus-iCycle) was adapted to create dual-arc VMAT treatment plan libraries for cervical cancer patients. For each of 34 patients, automatically generated VMAT plans (autoVMAT) were compared to manually generated, clinically delivered 9-be...

  3. Linear programming based on neural networks for radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Xingen Wu; Limin Luo

    2000-01-01

    In this paper, we propose a neural network model for linear programming that is designed to optimize radiotherapy treatment planning (RTP). This kind of neural network can be easily implemented by using a kind of 'neural' electronic system in order to obtain an optimization solution in real time. We first give an introduction to the RTP problem and construct a non-constraint objective function for the neural network model. We adopt a gradient algorithm to minimize the objective function and design the structure of the neural network for RTP. Compared to traditional linear programming methods, this neural network model can reduce the time needed for convergence, the size of problems (i.e., the number of variables to be searched) and the number of extra slack and surplus variables needed. We obtained a set of optimized beam weights that result in a better dose distribution as compared to that obtained using the simplex algorithm under the same initial condition. The example presented in this paper shows that this model is feasible in three-dimensional RTP. (author)

  4. A multi-modality concept for radiotherapy planning with imaging techniques

    International Nuclear Information System (INIS)

    Schultze, J.

    1993-01-01

    The reported multi-modality concept of radiotherapy planning in the LAN can be realised in any hospital with standard equipment, although in some cases by way of auxiliary configurations. A software is currently developed as a tool for reducing the entire planning work. The heart of any radiotherapy planning is the therapy simulator, which has to be abreast with the requirements of modern radiotherapy. Integration of tomograpy, digitalisation, and electronic data processing has added important modalities to therapy planning which allow more precise target volume definition, and better biophysical planning. This is what is needed in order to achieve well differentiated radiotherapy for treatment of the manifold tumors, and the quality standards expected by the supervisory quality assurance regime and the population. At present, the CT data still are transferred indirect, on storage media, to the EDP processing system of the radiotherapy planning system. Based on the tomographic slices given by the imaging data, the contours and technical problem solutions are derived automatically, either for multi-field radiotherapy or moving field irradiation, depending on the anatomy or the targets to be protected from ionizing radiation. (orig./VHE) [de

  5. Radiotherapy

    Directory of Open Access Journals (Sweden)

    Rema Jyothirmayi

    1999-01-01

    Full Text Available Purpose. Conservative treatment in the form of limited surgery and post-operative radiotherapy is controversial in hand and foot sarcomas, both due to poor radiation tolerance of the palm and sole, and due to technical difficulties in achieving adequate margins.This paper describes the local control and survival of 41 patients with soft tissue sarcoma of the hand or foot treated with conservative surgery and radiotherapy. The acute and late toxicity of megavoltage radiotherapy to the hand and foot are described. The technical issues and details of treatment delivery are discussed. The factors influencing local control after radiotherapy are analysed.

  6. Four-dimensional gravity as an almost-Poisson system

    Science.gov (United States)

    Ita, Eyo Eyo

    2015-04-01

    In this paper, we examine the phase space structure of a noncanonical formulation of four-dimensional gravity referred to as the Instanton representation of Plebanski gravity (IRPG). The typical Hamiltonian (symplectic) approach leads to an obstruction to the definition of a symplectic structure on the full phase space of the IRPG. We circumvent this obstruction, using the Lagrange equations of motion, to find the appropriate generalization of the Poisson bracket. It is shown that the IRPG does not support a Poisson bracket except on the vector constraint surface. Yet there exists a fundamental bilinear operation on its phase space which produces the correct equations of motion and induces the correct transformation properties of the basic fields. This bilinear operation is known as the almost-Poisson bracket, which fails to satisfy the Jacobi identity and in this case also the condition of antisymmetry. We place these results into the overall context of nonsymplectic systems.

  7. Twistors and four-dimensional conformal field theory

    International Nuclear Information System (INIS)

    Singer, M.A.

    1990-01-01

    This is a report (with technical details omitted) on work concerned with generalizations to four dimensions of two-dimensional Conformed Field Theory. Accounts of this and related material are contained elsewhere. The Hilbert space of the four-dimensional theory has a natural interpretation in terms of massless spinor fields on real Minkowski space. From the twistor point of view this follows from the boundary CR-manifold P being precisely the space of light rays in real compactified Minkowski space. All the amplitudes can therefore be regarded as defined on Hilbert spaces built from Lorentzian spinor fields. Thus the twistor picture provides a kind of halfway house between the Lorentzian and Euclidean field theories. (author)

  8. Four-dimensional Printing of Liquid Crystal Elastomers.

    Science.gov (United States)

    Ambulo, Cedric P; Burroughs, Julia J; Boothby, Jennifer M; Kim, Hyun; Shankar, M Ravi; Ware, Taylor H

    2017-10-25

    Three-dimensional structures capable of reversible changes in shape, i.e., four-dimensional-printed structures, may enable new generations of soft robotics, implantable medical devices, and consumer products. Here, thermally responsive liquid crystal elastomers (LCEs) are direct-write printed into 3D structures with a controlled molecular order. Molecular order is locally programmed by controlling the print path used to build the 3D object, and this order controls the stimulus response. Each aligned LCE filament undergoes 40% reversible contraction along the print direction on heating. By printing objects with controlled geometry and stimulus response, magnified shape transformations, for example, volumetric contractions or rapid, repetitive snap-through transitions, are realized.

  9. Raman scattering in air: four-dimensional analysis

    International Nuclear Information System (INIS)

    Lin, Y.; Kessler, T.J.; Lawrence, G.N.

    1994-01-01

    Inertial confinement fusion requires propagation of high-intensity, pulse-shaped IR and UV laser beams through long air paths. Such beams are subject to energy losses and decreased beam quality as a result by stimulated rotational Raman scattering (SRRS). In this paper we describe how quantum fluctuations, stimulated Raman amplification, diffraction propagation, and optical aberrations interact during the propagation of short, high-power laser pulses using a four-dimensional (4-D) model of the optical beams and the medium. The 4-D model has been incorporated into a general optical-propagation computer program that allows the entire optical system to be modeled and that is implemented on high-end personal computers, workstations, and supercomputers. The numerical model is used to illustrate important phenomena in the evolution of the optical beams. In addition, the OMEGA Upgrade laser system is used as a design case to illustrate the various considerations for inertial confinement fusion laser design

  10. A DICOM-RT-based toolbox for the evaluation and verification of radiotherapy plans

    International Nuclear Information System (INIS)

    Spezi, E; Lewis, D G; Smith, C W

    2002-01-01

    The verification of radiotherapy plans is an essential step in the treatment planning process. This is especially important for highly conformal and IMRT plans which produce non-intuitive fluence maps and complex 3D dose distributions. In this work we present a DICOM (Digital Imaging and Communication in Medicine) based toolbox, developed for the evaluation and the verification of radiotherapy treatment plans. The toolbox offers the possibility of importing treatment plans generated with different calculation algorithms and/or different optimization engines and evaluating dose distributions on an independent platform. Furthermore the radiotherapy set-up can be exported to the BEAM Monte Carlo code system for dose verification. This can be done by simulating the irradiation of the patient CT dataset or the irradiation of a software-generated water phantom. We show the application of some of the functions implemented in this toolbox for the evaluation and verification of an IMRT treatment of the head and neck region

  11. A semiautomatic tool for prostate segmentation in radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Schulz, Jörn; Skrøvseth, Stein Olav; Tømmerås, Veronika Kristine; Marienhagen, Kirsten; Godtliebsen, Fred

    2014-01-01

    Delineation of the target volume is a time-consuming task in radiotherapy treatment planning, yet essential for a successful treatment of cancers such as prostate cancer. To facilitate the delineation procedure, the paper proposes an intuitive approach for 3D modeling of the prostate by slice-wise best fitting ellipses. The proposed estimate is initialized by the definition of a few control points in a new patient. The method is not restricted to particular image modalities but assumes a smooth shape with elliptic cross sections of the object. A training data set of 23 patients was used to calculate a prior shape model. The mean shape model was evaluated based on the manual contour of 10 test patients. The patient records of training and test data are based on axial T1-weighted 3D fast-field echo (FFE) sequences. The manual contours were considered as the reference model. Volume overlap (Vo), accuracy (Ac) (both ratio, range 0-1, optimal value 1) and Hausdorff distance (HD) (mm, optimal value 0) were calculated as evaluation parameters. The median and median absolute deviation (MAD) between manual delineation and deformed mean best fitting ellipses (MBFE) was Vo (0.9 ± 0.02), Ac (0.81 ± 0.03) and HD (4.05 ± 1.3)mm and between manual delineation and best fitting ellipses (BFE) was Vo (0.96 ± 0.01), Ac (0.92 ± 0.01) and HD (1.6 ± 0.27)mm. Additional results show a moderate improvement of the MBFE results after Monte Carlo Markov Chain (MCMC) method. The results emphasize the potential of the proposed method of modeling the prostate by best fitting ellipses. It shows the robustness and reproducibility of the model. A small sample test on 8 patients suggest possible time saving using the model

  12. The functional imaging in target volume delineation of radiotherapy planning for gliomas

    International Nuclear Information System (INIS)

    Huang Jingxiong; Wu Hua

    2007-01-01

    Radiotherapy is one of important treatments for glioma. Functional imaging, such as PET, SPECT and MRI, may provide more valuable information not only in display of the evasion extent of glioma but also in demonstration of some biological characteristics of the tumor, such as perfusion, metabolism, hypoxia or proliferation. Thus it may play a role in making an individualized and more exact radiotherapy planning. (authors)

  13. Four-Dimensional Data Assimilation Using the Adjoint Method

    Science.gov (United States)

    Bao, Jian-Wen

    The calculus of variations is used to confirm that variational four-dimensional data assimilation (FDDA) using the adjoint method can be implemented when the numerical model equations have a finite number of first-order discontinuous points. These points represent the on/off switches associated with physical processes, for which the Jacobian matrix of the model equation does not exist. Numerical evidence suggests that, in some situations when the adjoint method is used for FDDA, the temperature field retrieved using horizontal wind data is numerically not unique. A physical interpretation of this type of non-uniqueness of the retrieval is proposed in terms of energetics. The adjoint equations of a numerical model can also be used for model-parameter estimation. A general computational procedure is developed to determine the size and distribution of any internal model parameter. The procedure is then applied to a one-dimensional shallow -fluid model in the context of analysis-nudging FDDA: the weighting coefficients used by the Newtonian nudging technique are determined. The sensitivity of these nudging coefficients to the optimal objectives and constraints is investigated. Experiments of FDDA using the adjoint method are conducted using the dry version of the hydrostatic Penn State/NCAR mesoscale model (MM4) and its adjoint. The minimization procedure converges and the initialization experiment is successful. Temperature-retrieval experiments involving an assimilation of the horizontal wind are also carried out using the adjoint of MM4.

  14. The NUKDOS software for treatment planning in molecular radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kletting, Peter; Schimmel, Sebastian [Univ. Ulm (Germany). Klinik fuer Nuklearmedizin; Haenscheid, Heribert; Fernandez, Maria; Lassmann, Michael [Univ. Wuerzburg (Germany). Klinik fuer Nuklearmedizin; Luster, Markus [Univ. Marburg (Germany). Klinik fuer Nuklearmedizin; Nosske, Dietmar [Bundesamt fuer Strahlenschutz, Fachbereich Strahlenschutz und Gesundheit, Oberschleissheim (Germany); Glatting, Gerhard [Heidelberg Univ., Medical Radiation Physics/Radiation Protection, Mannheim (Germany)

    2015-07-01

    The aim of this work was the development of a software tool for treatment planning prior to molecular radiotherapy, which comprises all functionality to objectively determine the activity to administer and the pertaining absorbed doses (including the corresponding error) based on a series of gamma camera images and one SPECT/CT or probe data. NUKDOS was developed in MATLAB. The workflow is based on the MIRD formalism For determination of the tissue or organ pharmacokinetics, gamma camera images as well as probe, urine, serum and blood activity data can be processed. To estimate the time-integrated activity coefficients (TIAC), sums of exponentials are fitted to the time activity data and integrated analytically. To obtain the TIAC on the voxel level, the voxel activity distribution from the quantitative 3D SPECT/CT (or PET/CT) is used for scaling and weighting the TIAC derived from the 2D organ data. The voxel S-values are automatically calculated based on the voxel-size of the image and the therapeutic nuclide ({sup 90}Y, {sup 131}I or {sup 177}Lu). The absorbed dose coefficients are computed by convolution of the voxel TIAC and the voxel S-values. The activity to administer and the pertaining absorbed doses are determined by entering the absorbed dose for the organ at risk. The overall error of the calculated absorbed doses is determined by Gaussian error propagation. NUKDOS was tested for the operation systems Windows {sup registered} 7 (64 Bit) and 8 (64 Bit). The results of each working step were compared to commercially available (SAAMII, OLINDA/EXM) and in-house (UlmDOS) software. The application of the software is demonstrated using examples form peptide receptor radionuclide therapy (PRRT) and from radioiodine therapy of benign thyroid diseases. For the example from PRRT, the calculated activity to administer differed by 4% comparing NUKDOS and the final result using UlmDos, SAAMII and OLINDA/EXM sequentially. The absorbed dose for the spleen and tumour

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

    Directory of Open Access Journals (Sweden)

    Kalemba Mwambazambi

    2014-02-01

    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.

  16. Semiautomated four-dimensional computed tomography segmentation using deformable models

    International Nuclear Information System (INIS)

    Ragan, Dustin; Starkschall, George; McNutt, Todd; Kaus, Michael; Guerrero, Thomas; Stevens, Craig W.

    2005-01-01

    The purpose of this work is to demonstrate a proof of feasibility of the application of a commercial prototype deformable model algorithm to the problem of delineation of anatomic structures on four-dimensional (4D) computed tomography (CT) image data sets. We acquired a 4D CT image data set of a patient's thorax that consisted of three-dimensional (3D) image data sets from eight phases in the respiratory cycle. The contours of the right and left lungs, cord, heart, and esophagus were manually delineated on the end inspiration data set. An interactive deformable model algorithm, originally intended for deforming an atlas-based model surface to a 3D CT image data set, was applied in an automated fashion. Triangulations based on the contours generated on each phase were deformed to the CT data set on the succeeding phase to generate the contours on that phase. Deformation was propagated through the eight phases, and the contours obtained on the end inspiration data set were compared with the original manually delineated contours. Structures defined by high-density gradients, such as lungs, cord, and heart, were accurately reproduced, except in regions where other gradient boundaries may have confused the algorithm, such as near bronchi. The algorithm failed to accurately contour the esophagus, a soft-tissue structure completely surrounded by tissue of similar density, without manual interaction. This technique has the potential to facilitate contour delineation in 4D CT image data sets; and future evolution of the software is expected to improve the process

  17. Dosimetric aspects of breast radiotherapy with three-dimensional and intensity-modulated radiotherapy helical tomotherapy planning modules

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Poonam [Department of Human Oncology, University of Wisconsin-Madison, Madison, WI (United States); Service of Radiation Therapy, University of Wisconsin Aspirus Cancer Center, Wisconsin Rapids, WI (United States); Yan, Yue, E-mail: yyan5@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX (United States); Ignatowski, Tasha [Service of Radiation Therapy, University of Wisconsin Aspirus Cancer Center, Wisconsin Rapids, WI (United States); Olson, Anna [Department of Human Oncology, University of Wisconsin-Madison, Madison, WI (United States); Service of Radiation Therapy, University of Wisconsin Aspirus Cancer Center, Wisconsin Rapids, WI (United States)

    2017-04-01

    In this work, we investigated the dosimetric differences between the intensity-modulated radiotherapy (IMRT) plans and the three-dimensional (3D) helical plans based on the TomoTherapy system. A total of 15 patients with supine setup were randomly selected from the data base. For patients with lumpectomy planning target volume (PTV), regional lymph nodes were also included as part of the target. For dose sparing, the significant differences between the helical IMRT and helical 3D were only found in the heart and contralateral breast. For the dose to the heart, helical IMRT reduced the maximum point dose by 6.98 Gy compared to the helical 3D plan (p = 0.01). For contralateral breast, the helical IMRT plans significantly reduced the maximum point dose by 5.6 Gy compared to the helical 3D plan. However, compared to the helical 3D plan, the helical IMRT plan increased the volume for lower dose (13.08% increase in V{sub 5} {sub Gy}, p = 0.01). In general, there are no significant differences in dose sparing between helical IMRT and helical 3D plans.

  18. Dosimetric aspects of breast radiotherapy with three-dimensional and intensity-modulated radiotherapy helical tomotherapy planning modules

    International Nuclear Information System (INIS)

    Yadav, Poonam; Yan, Yue; Ignatowski, Tasha; Olson, Anna

    2017-01-01

    In this work, we investigated the dosimetric differences between the intensity-modulated radiotherapy (IMRT) plans and the three-dimensional (3D) helical plans based on the TomoTherapy system. A total of 15 patients with supine setup were randomly selected from the data base. For patients with lumpectomy planning target volume (PTV), regional lymph nodes were also included as part of the target. For dose sparing, the significant differences between the helical IMRT and helical 3D were only found in the heart and contralateral breast. For the dose to the heart, helical IMRT reduced the maximum point dose by 6.98 Gy compared to the helical 3D plan (p = 0.01). For contralateral breast, the helical IMRT plans significantly reduced the maximum point dose by 5.6 Gy compared to the helical 3D plan. However, compared to the helical 3D plan, the helical IMRT plan increased the volume for lower dose (13.08% increase in V 5 Gy , p = 0.01). In general, there are no significant differences in dose sparing between helical IMRT and helical 3D plans.

  19. 18F-fluorodeoxyglucose PET in definition of target volumes and radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Qiao Wenli; Zhao Jinhua

    2007-01-01

    PET is a functional imaging modality, which can give some biological information of tumor. PET is more and more important in the definition of target volumes and radiotherapy treatment planning. Depending on its sensitivity and specificity, 18 F-fluorideoxyglucose 18 F-FDG PET has been shown to influence the selection of target volumes and radiotherapy treatment planning for non-small cell lung cancers, for head and neck squamous cell carcinomas or for esophageal tumors. On the other hand, for tumors such as rectal carcinomas, convincing data on the value of 18 F-FDG PET for target volume selection are still lacking. However, the application of 18 F-FDG PET in many aspects of radiotherapy is still controversy. Further researches in its clinical application are still needed to investigate whether 18 F-FDG PET for treatment planning should be routine because of the lack of prospective studies. (authors)

  20. Recommendations for the use of PET and PET-CT for radiotherapy planning in research projects.

    Science.gov (United States)

    Somer, E J; Pike, L C; Marsden, P K

    2012-08-01

    With the increasing use of positron emission tomography (PET) for disease staging, follow-up and therapy monitoring in a number of oncological indications there is growing interest in the use of PET and PET-CT for radiation treatment planning. In order to create a strong clinical evidence base for this, it is important to ensure that research data are clinically relevant and of a high quality. Therefore the National Cancer Research Institute PET Research Network make these recommendations to assist investigators in the development of radiotherapy clinical trials involving the use of PET and PET-CT. These recommendations provide an overview of the current literature in this rapidly evolving field, including standards for PET in clinical trials, disease staging, volume delineation, intensity modulated radiotherapy and PET-augmented planning techniques, and are targeted at a general audience. We conclude with specific recommendations for the use of PET in radiotherapy planning in research projects.

  1. Nonrigid Image Registration for Head and Neck Cancer Radiotherapy Treatment Planning With PET/CT

    International Nuclear Information System (INIS)

    Ireland, Rob H.; Dyker, Karen E.; Barber, David C.; Wood, Steven M.; Hanney, Michael B.; Tindale, Wendy B.; Woodhouse, Neil; Hoggard, Nigel; Conway, John; Robinson, Martin H.

    2007-01-01

    Purpose: Head and neck radiotherapy planning with positron emission tomography/computed tomography (PET/CT) requires the images to be reliably registered with treatment planning CT. Acquiring PET/CT in treatment position is problematic, and in practice for some patients it may be beneficial to use diagnostic PET/CT for radiotherapy planning. Therefore, the aim of this study was first to quantify the image registration accuracy of PET/CT to radiotherapy CT and, second, to assess whether PET/CT acquired in diagnostic position can be registered to planning CT. Methods and Materials: Positron emission tomography/CT acquired in diagnostic and treatment position for five patients with head and neck cancer was registered to radiotherapy planning CT using both rigid and nonrigid image registration. The root mean squared error for each method was calculated from a set of anatomic landmarks marked by four independent observers. Results: Nonrigid and rigid registration errors for treatment position PET/CT to planning CT were 2.77 ± 0.80 mm and 4.96 ± 2.38 mm, respectively, p = 0.001. Applying the nonrigid registration to diagnostic position PET/CT produced a more accurate match to the planning CT than rigid registration of treatment position PET/CT (3.20 ± 1.22 mm and 4.96 ± 2.38 mm, respectively, p = 0.012). Conclusions: Nonrigid registration provides a more accurate registration of head and neck PET/CT to treatment planning CT than rigid registration. In addition, nonrigid registration of PET/CT acquired with patients in a standardized, diagnostic position can provide images registered to planning CT with greater accuracy than a rigid registration of PET/CT images acquired in treatment position. This may allow greater flexibility in the timing of PET/CT for head and neck cancer patients due to undergo radiotherapy

  2. Commissioning and quality assurances of the CMS XIO radiotherapy treatment planning system for external beam photons

    International Nuclear Information System (INIS)

    Muralidhar, K.R.; Anurupa; Soubhagya; Sudhakar; Shiva; Krishnam Raju, A.; Narayana Murthy, P.

    2008-01-01

    The commissioning of XIO treatment planning system (TPS) was carried out by Computerized Medical Devices, USA for Siemens and Elekta linear accelerators. The Commissioning and quality assurance of the CMS XIO radiotherapy treatment planning system involves many steps, beginning from beam data acquisition and entry into the computerized TPS, through patient data acquisition, to treatment plan generation and the final transfer of data to the treatment machine and quality assurance of TPS

  3. Radiotherapy

    International Nuclear Information System (INIS)

    Wannenmacher, M.; Debus, J.; Wenz, F.

    2006-01-01

    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

  4. IMRT, IGRT, SBRT - Advances in the Treatment Planning and Delivery of Radiotherapy

    CERN Document Server

    Meyer, JL

    2011-01-01

    Over the last 4 years, IMRT, IGRT, SBRT: Advances in the Treatment Planning and Delivery of Radiotherapy has become a standard reference in the field. During this time, however, significant progress in high-precision technologies for the planning and delivery of radiotherapy in cancer treatment has called for a second edition to include these new developments. Thoroughly updated and extended, this new edition offers a comprehensive guide and overview of these new technologies and the many clinical treatment programs that bring them into practical use. Advances in intensity-modulated radiothera

  5. Defining internal target volume (ITV) for hepatocellular carcinoma using four-dimensional CT

    International Nuclear Information System (INIS)

    X, Mian; Liu Mengzhong; Deng Xiaowu; Zhang Li; Huang Xiaoyan; Liu Hui; Li Qiaoqiao; Hu Yonghong; Cai Ling; Cui Nianji

    2007-01-01

    Background and purpose: To define individualized internal target volume (ITV) for hepatocellular carcinoma using four-dimensional computed tomography (4DCT). Materials and methods: Gross tumor volumes (GTVs) and clinical target volumes (CTVs) were contoured on all 10 respiratory phases of 4DCT scans in 10 patients with hepatocellular carcinoma. The 3D and 4D treatment plans were performed for each patient using two different planning target volumes (PTVs): (1) PTV 3D was derived from a single CTV plus conventional margins; (2) PTV 4D was derived from ITV 4D , which encompassed all 10 CTVs plus setup margins (SMs). The volumes of PTVs and dose distribution were compared between the two plans. Results: The average PTV volume of the 4D plans (328.4 ± 152.2 cm 3 ) was less than 3D plans (407.0 ± 165.6 cm 3 ). The 4D plans spared more surrounding normal tissues than 3D plans, especially normal liver. Compared with 3D plans, the mean dose to normal liver (MDTNL) decreased from 22.7 to 20.3 Gy. Without increasing the normal tissue complication probability (NTCP), the 4D plans allowed for increasing the calculated dose from 50.4 ± 1.3 to 54.2 ± 2.6 Gy, an average increase of 7.5% (range 4.0-16.0%). Conclusions: The conventional 3D plans can result in geometric miss and include excess normal tissues. The 4DCT-based plans can reduce the target volumes to spare more normal tissues and allow dose escalation compared with 3D plans

  6. Radiotherapy.

    Science.gov (United States)

    Krause, Sonja; Debus, Jürgen; Neuhof, Dirk

    2011-01-01

    Solitary plasmocytoma occurring in bone (solitary plasmocytoma of the bone, SBP) or in soft tissue (extramedullary plasmocytoma, EP) can be treated effectively and with little toxicity by local radiotherapy. Ten-year local control rates of up to 90% can be achieved. Patients with multiple myeloma often suffer from symptoms such as pain or neurological impairments that are amenable to palliative radiotherapy. In a palliative setting, short treatment schedules and lower radiation doses are used to reduce toxicity and duration of hospitalization. In future, low-dose total body irradiation (TBI) may play a role in a potentially curative regimen with nonmyeloablative conditioning followed by allogenic peripheral blood stem cell transplantation.

  7. Planning target volumes for radiotherapy: how much margin is needed?

    International Nuclear Information System (INIS)

    Antolak, John A.; Rosen, Isaac I.

    1999-01-01

    Purpose: The radiotherapy planning target volume (PTV) encloses the clinical target volume (CTV) with anisotropic margins to account for possible uncertainties in beam alignment, patient positioning, organ motion, and organ deformation. Ideally, the CTV-PTV margin should be determined solely by the magnitudes of the uncertainties involved. In practice, the clinician usually also considers doses to abutting healthy tissues when deciding on the size of the CTV-PTV margin. This study calculates the ideal size of the CTV-PTV margin when only physical position uncertainties are considered. Methods and Materials: The position of the CTV for any treatment is assumed to be described by independent Gaussian distributions in each of the three Cartesian directions. Three strategies for choosing a CTV-PTV margin are analyzed. The CTV-PTV margin can be based on: 1. the probability that the CTV is completely enclosed by the PTV; 2. the probability that the projection of the CTV in the beam's eye view (BEV) is completely enclosed by the projection of the PTV in the BEV; and 3. the probability that a point on the edge of the CTV is within the PTV. Cumulative probability distributions are derived for each of the above strategies. Results: Expansion of the CTV by 1 standard deviation (SD) in each direction results in the CTV being entirely enclosed within the PTV 24% of the time; the BEV projection of the CTV is enclosed within the BEV projection of the PTV 39% of the time; and a point on the edge of the CTV is within the PTV 84% of the time. To have the CTV enclosed entirely within the PTV 95% of the time requires a margin of 2.8 SD. For the BEV projection of the CTV to be within the BEV projection of the PTV 95% of the time requires a margin of 2.45 SD. To have any point on the surface of the CTV be within the PTV 95% of the time requires a margin of 1.65 SD. Conclusion: In the first two strategies for selecting a margin, the probability of finding the CTV within the PTV is

  8. Evaluation of isocenter reproducibility in telemedicine of 3D-radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Hirota, Saeko; Tsujino, Kayoko; Kimura, Kouji; Takada, Yoshiki; Hishikawa, Yoshio; Kono, Michio; Soejima, Toshinori; Kodama, Akihisa

    2000-01-01

    To evaluate the utility in telemedicine of Three-Dimensional Radiotherapy Treatment Planning (tele-3D-RTP) and to examine the accuracy of isocenter reproducibility in its offline trial. CT data of phantoms and patients in the satellite hospital were transferred to our hospital via floppy-disk and 3D-radiotherapy plans were generated by 3D-RTP computer in our hospital. Profile data of CT and treatment beams in the satellite hospital were pre-installed into the computer. Tele-3D-RTPs were performed in 3 phantom plans and 14 clinical plans for 13 patients. Planned isocenters were well reproduced, especially in the immobilized head and neck/brain tumor cases, whose 3D-vector of aberration was 1.96±1.38 (SD) mm. This teletherapy system is well applicable for practical use and can provides cost-reduction through sharing the resources of expensive equipment and radiation oncologists. (author)

  9. Evaluation of isocenter reproducibility in telemedicine of 3D-radiotherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Hirota, Saeko; Tsujino, Kayoko; Kimura, Kouji; Takada, Yoshiki; Hishikawa, Yoshio; Kono, Michio [Hyogo Medical Center for Adults, Akashi (Japan); Soejima, Toshinori; Kodama, Akihisa

    2000-09-01

    To evaluate the utility in telemedicine of Three-Dimensional Radiotherapy Treatment Planning (tele-3D-RTP) and to examine the accuracy of isocenter reproducibility in its offline trial. CT data of phantoms and patients in the satellite hospital were transferred to our hospital via floppy-disk and 3D-radiotherapy plans were generated by 3D-RTP computer in our hospital. Profile data of CT and treatment beams in the satellite hospital were pre-installed into the computer. Tele-3D-RTPs were performed in 3 phantom plans and 14 clinical plans for 13 patients. Planned isocenters were well reproduced, especially in the immobilized head and neck/brain tumor cases, whose 3D-vector of aberration was 1.96{+-}1.38 (SD) mm. This teletherapy system is well applicable for practical use and can provides cost-reduction through sharing the resources of expensive equipment and radiation oncologists. (author)

  10. Dosimetric comparison between intensity modulated brachytherapy versus external beam intensity modulated radiotherapy for cervix cancer: a treatment planning study

    International Nuclear Information System (INIS)

    Subramani, V.; Sharma, D.N.; Jothy Basu, K.S.; Rath, G.K.; Gopishankar, N.

    2008-01-01

    To evaluate the dosimetric superiority of intensity modulated brachytherapy (IMBT) based on inverse planning optimization technique with classical brachytherapy optimization and also with external beam intensity modulated radiotherapy planning technique in patients of cervical carcinoma

  11. Clinical treatment planning for stereotactic radiotherapy, evaluation by Monte Carlo simulation

    International Nuclear Information System (INIS)

    Kairn, T.; Aland, T.; Kenny, J.; Knight, R.T.; Crowe, S.B.; Langton, C.M.; Franich, R.D.; Johnston, P.N.

    2010-01-01

    Full text: This study uses re-evaluates the doses delivered by a series of clinical stereotactic radiotherapy treatments, to test the accuracy of treatment planning predictions for very small radiation fields. Stereotactic radiotherapy treatment plans for meningiomas near the petrous temporal bone and the foramen magnum (incorp rating fields smaller than I c m2) were examined using Monte Carlo simulations. Important differences between treatment planning predictions and Monte Carlo calculations of doses delivered to stereotactic radiotherapy patients are apparent. For example, in one case the Monte Carlo calculation shows that the delivery a planned meningioma treatment would spare the patient's critical structures (eyes, brainstem) more effectively than the treatment plan predicted, and therefore suggests that this patient could safely receive an increased dose to their tumour. Monte Carlo simulations can be used to test the dose predictions made by a conventional treatment planning system, for dosimetrically challenging small fields, and can thereby suggest valuable modifications to clinical treatment plans. This research was funded by the Wesley Research Institute, Australia. The authors wish to thank Andrew Fielding and David Schlect for valuable discussions of aspects of this work. The authors are also grateful to Muhammad Kakakhel, for assisting with the design and calibration of our linear accelerator model, and to the stereotactic radiation therapy team at Premion, who designed the treatment plans. Computational resources and services used in this work were provided by the HPC and Research Support Unit, QUT, Brisbane, Australia. (author)

  12. Target volume definition with 18F-FDG PET-CT in radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Carson, K. J.; Hanna, G. G.; Hounsell, A. R.

    2011-01-01

    There is considerable interest in using 18F -Fluorodeoxyglucose (FDG) positron emission tomography (PET) images for radiotherapy treatment planning (RTF) purposes, and in particular for defining target volumes. This is a rapidly evolving subject and this review describes the background to this application of PET imaging and discusses the issues involved. (authors)

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

    Science.gov (United States)

    Tian, Bing; Xu, Bing; Lu, Jianping; Liu, Qi; Wang, Li; Wang, Minjie

    2015-06-01

    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. 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. 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. 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. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  14. 3D Conformal radiotherapy for gastric cancer-results of a comparative planning study

    International Nuclear Information System (INIS)

    Leong, Trevor; Willis, David; Joon, Daryl Lim; Condron, Sara; Hui, Andrew; Ngan, Samuel Y.K.

    2005-01-01

    Background and purpose: Many radiation oncologists are reluctant to use anteroposterior-posteroanterior (AP-PA) field arrangements when treating gastric cancer with adjuvant postoperative radiotherapy due to concerns about normal tissue toxicity, particularly in relation to the kidneys and spinal cord. In this report, we describe a multiple-field conformal radiotherapy technique, and compare this technique to the more commonly used AP-PA technique that was used in the recently reported Intergroup study (INT0116). Materials and methods: Fifteen patients with stages II-IV adenocarcinoma of the stomach were treated with adjuvant postoperative chemoradiotherapy using a standardised 3D conformal radiotherapy technique that consisted of a 'split-field', mono-isocentric arrangement employing 6 radiation fields. For each patient, a second radiotherapy treatment plan was generated utilising AP-PA fields. The two techniques were then compared for target volume coverage and dose to normal tissues using dose volume histogram (DVH) analysis. Results: The conformal technique provides more adequate coverage of the target volume with 99% of the planning target volume (PTV) receiving 95% of the prescribed dose, compared to 93% using AP-PA fields. Comparative DVHs for the right kidney, left kidney and spinal cord demonstrate lower radiation doses using the conformal technique, and although the liver dose is higher, it is still well below liver tolerance. Conclusions: 3D conformal radiotherapy produces superior dose distributions and reduced radiation doses to the kidneys and spinal cord compared to AP-PA techniques, with the potential to reduce treatment toxicity

  15. Radiotherapy

    International Nuclear Information System (INIS)

    Pistenma, D.A.

    1980-01-01

    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

  16. Treatment Planning Study to Determine Potential Benefit of Intensity-Modulated Radiotherapy Versus Conformal Radiotherapy for Unresectable Hepatic Malignancies

    International Nuclear Information System (INIS)

    Eccles, Cynthia L.; Bissonnette, Jean-Pierre; Craig, Tim; Taremi, Mojgan; Wu Xia; Dawson, Laura A.

    2008-01-01

    Purpose: To compare intensity-modulated radiotherapy (IMRT) with conformal RT (CRT) for hypofractionated isotoxicity liver RT and explore dose escalation using IMRT for the same/improved nominal risk of liver toxicity in a treatment planning study. Methods and Materials: A total of 26 CRT plans were evaluated. Prescription doses (24-54 Gy within six fractions) were individualized on the basis of the effective liver volume irradiated maintaining ≤5% risk of radiation-induced liver disease. The dose constraints included bowel (0.5 cm 3 ) and stomach (0.5 cm 3 ) to ≤30 Gy, spinal cord to ≤25 Gy, and planning target volume (PTV) to ≤140% of the prescribed dose. Two groups were evaluated: (1) PTV overlapping or directly adjacent to serial functioning normal tissues (n = 14), and (2) the liver as the dose-limiting normal tissue (n = 12). IMRT plans using direct machine parameter optimization maintained the CRT plan beam arrangements, an estimated radiation-induced liver disease risk of 5%, and underwent dose escalation, if all normal tissue constraints were maintained. Results: IMRT improved PTV coverage in 19 of 26 plans (73%). Dose escalation was feasible in 9 cases by an average of 3.8 Gy (range, 0.6-13.2) in six fractions. Three of seven plans without improved PTV coverage had small gross tumor volumes (≤105 cm 3 ) already receiving 54 Gy, the maximal prescription dose allowed. In the remaining cases, the PTV range was 9.6-689 cm 3 ; two had overlapped organs at risk; and one had four targets. IMRT did not improve these plans owing to poor target coverage (n = 2) and nonliver (n = 2) dose limits. Conclusion: Direct machine parameter optimization IMRT improved PTV coverage while maintaining normal tissue tolerances in most CRT liver plans. Dose escalation was possible in a minority of patients

  17. Protocol for quality control of scanners used in the simulation of radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Yanes, Yaima; Alfonso, Rodolfo; Silvestre, Ileana

    2009-01-01

    Computed Tomography (CT) has become the tool fundamental imaging of modern radiation therapy, to locate targets and critical organs and dose planning. Tomographs used for these purposes require strict assurance program quality, which differs in many aspects of monitoring required for diagnostic use only with intention. The aim of this work has been the design and validation of a quality control protocol applicable to any TAC used for simulation, radiotherapy planning. (author)

  18. A semi-analytical radiobiological model may assist treatment planning in light ion radiotherapy

    Czech Academy of Sciences Publication Activity Database

    Kundrát, Pavel

    2007-01-01

    Roč. 52, č. 23 (2007), s. 6813-6830 ISSN 0031-9155 R&D Projects: GA ČR GA202/05/2728 Institutional research plan: CEZ:AV0Z10100502 Keywords : Bragg peak * light ions * hadron * hadron radiotherapy * biological effectiveness * treatment planning Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 2.528, year: 2007

  19. Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit

    OpenAIRE

    Rutonjski Laza; Petrović Borislava; Baucal Milutin; Teodorović Milan; Čudić Ozren; Gershkevitsh Eduard; Izewska Joanna

    2012-01-01

    Abstract Background Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. Methods The audit was conducte...

  20. Automated planning of breast radiotherapy using cone beam CT imaging

    International Nuclear Information System (INIS)

    Amit, Guy; Purdie, Thomas G.

    2015-01-01

    Purpose: Develop and clinically validate a methodology for using cone beam computed tomography (CBCT) imaging in an automated treatment planning framework for breast IMRT. Methods: A technique for intensity correction of CBCT images was developed and evaluated. The technique is based on histogram matching of CBCT image sets, using information from “similar” planning CT image sets from a database of paired CBCT and CT image sets (n = 38). Automated treatment plans were generated for a testing subset (n = 15) on the planning CT and the corrected CBCT. The plans generated on the corrected CBCT were compared to the CT-based plans in terms of beam parameters, dosimetric indices, and dose distributions. Results: The corrected CBCT images showed considerable similarity to their corresponding planning CTs (average mutual information 1.0±0.1, average sum of absolute differences 185 ± 38). The automated CBCT-based plans were clinically acceptable, as well as equivalent to the CT-based plans with average gantry angle difference of 0.99°±1.1°, target volume overlap index (Dice) of 0.89±0.04 although with slightly higher maximum target doses (4482±90 vs 4560±84, P < 0.05). Gamma index analysis (3%, 3 mm) showed that the CBCT-based plans had the same dose distribution as plans calculated with the same beams on the registered planning CTs (average gamma index 0.12±0.04, gamma <1 in 99.4%±0.3%). Conclusions: The proposed method demonstrates the potential for a clinically feasible and efficient online adaptive breast IMRT planning method based on CBCT imaging, integrating automation

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

    International Nuclear Information System (INIS)

    Lin, Kuan-Min; Simpson, John; Raith, Andrea; Ehrgott, Matthias; Sasso, Giuseppe

    2013-01-01

    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)

  2. Proposal for development of a system for planning radiotherapy of gliomas

    International Nuclear Information System (INIS)

    Caldeira, Alexandre D.

    2015-01-01

    In the last three years, discussions were held on several topics in Nuclear Medicine area, starting with the nuclear data processing, passing by deterministic and stochastic mathematical methods, and finalizing with computer simulations of the following phenomena: neutron transport, applied to boron neutron capture therapy, and neutron diffusion, to study growth of tumor cells. From a mathematical model applied to radiotherapy of gliomas available in literature, it is proposed a strategy for development of a computer system to assist the planning radiotherapy of gliomas. (author)

  3. An approach to contouring the dorsal vagal complex for radiotherapy planning

    Energy Technology Data Exchange (ETDEWEB)

    O' Steen, Lillie; Amdur, Robert J., E-mail: amdurr@shands.ufl.edu

    2016-04-01

    Multiple studies suggest that radiation dose to the area of the brainstem called the “dorsal vagal complex (DVC)” influences the frequency of nausea and vomiting during radiotherapy. The purpose of this didactic article is to describe the step-by-step process that we use to contour the general area of the DVC on axial computed tomography (CT) images as would be done for radiotherapy planning. The contouring procedure that we describe for contouring the area of the DVC is useful to medical dosimetrists and radiation oncologists.

  4. Integration of second cancer risk calculations in a radiotherapy treatment planning system

    International Nuclear Information System (INIS)

    Hartmann, M; Schneider, U

    2014-01-01

    Second cancer risk in patients, in particular in children, who were treated with radiotherapy is an important side effect. It should be minimized by selecting an appropriate treatment plan for the patient. The objectives of this study were to integrate a risk model for radiation induced cancer into a treatment planning system which allows to judge different treatment plans with regard to second cancer induction and to quantify the potential reduction in predicted risk. A model for radiation induced cancer including fractionation effects which is valid for doses in the radiotherapy range was integrated into a treatment planning system. From the three-dimensional (3D) dose distribution the 3D-risk equivalent dose (RED) was calculated on an organ specific basis. In addition to RED further risk coefficients like OED (organ equivalent dose), EAR (excess absolute risk) and LAR (lifetime attributable risk) are computed. A risk model for radiation induced cancer was successfully integrated in a treatment planning system. Several risk coefficients can be viewed and used to obtain critical situations were a plan can be optimised. Risk-volume-histograms and organ specific risks were calculated for different treatment plans and were used in combination with NTCP estimates for plan evaluation. It is concluded that the integration of second cancer risk estimates in a commercial treatment planning system is feasible. It can be used in addition to NTCP modelling for optimising treatment plans which result in the lowest possible second cancer risk for a patient.

  5. Power Doppler flow mapping and four-dimensional ultrasound for evaluating tubal patency compared with laparoscopy.

    Science.gov (United States)

    Soliman, Amr A; Shaalan, Waleed; Abdel-Dayem, Tamer; Awad, Elsayed Elbadawy; Elkassar, Yasser; Lüdders, Dörte; Malik, Eduard; Sallam, Hassan N

    2015-12-01

    To study the accuracy of four-dimensional (4D) ultrasound and power Doppler flow mapping in detecting tubal patency in women with sub-/infertility, and compare it with laparoscopy and chromopertubation. A prospective study. The study was performed in the outpatient clinic and infertility unit of a university hospital. The sonographic team and laparoscopic team were blinded to the results of each other. Women aged younger than 43 years seeking medical advice due to primary or secondary infertility and who planned to have a diagnostic laparoscopy performed, were recruited to the study after signing an informed consent. All of the recruited patients had power Doppler flow mapping and 4D hysterosalpingo-sonography by injecting sterile saline into the fallopian tubes 1 day before surgery. Registering Doppler signals, while using power Doppler, both at the tubal ostia and fimbrial end and the ability to demonstrate the course of the tube especially the isthmus and fimbrial end, while using 4D mode, was considered a patent tube. Out of 50 recruited patients, 33 women had bilateral patent tubes and five had unilateral patent tubes as shown by chromopertubation during diagnostic laparoscopy. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for two-dimensional power Doppler hysterosalpingography were 94.4%, 100%, 100%, 89.2%, and 96.2%, respectively and for 4D ultrasound were 70.4%, 100%, 100%, 70.4%, and 82.6%, respectively. Four-dimensional saline hysterosalpingography has acceptable accuracy in detecting tubal patency, but is surpassed by power Doppler saline hysterosalpingography. Power Doppler saline hysterosalpingography could be incorporated into the routine sub-/infertility workup. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  6. Evaluation and scoring of radiotherapy treatment plans using an artificial neural network

    International Nuclear Information System (INIS)

    Willoughby, Twyla R.; Starkschall, George; Janjan, Nora A.; Rosen, Isaac I.

    1996-01-01

    Purpose: The objective of this work was to demonstrate the feasibility of using an artificial neural network to predict the clinical evaluation of radiotherapy treatment plans. Methods and Materials: Approximately 150 treatment plans were developed for 16 patients who received external-beam radiotherapy for soft-tissue sarcomas of the lower extremity. Plans were assigned a figure of merit by a radiation oncologist using a five-point rating scale. Plan scoring was performed by a single physician to ensure consistency in rating. Dose-volume information extracted from a training set of 511 treatment plans on 14 patients was correlated to the physician-generated figure of merit using an artificial neural network. The neural network was tested with a test set of 19 treatment plans on two patients whose plans were not used in the training of the neural net. Results: Physician scoring of treatment plans was consistent to within one point on the rating scale 88% of the time. The neural net reproduced the physician scores in the training set to within one point approximately 90% of the time. It reproduced the physician scores in the test set to within one point approximately 83% of the time. Conclusions: An artificial neural network can be trained to generate a score for a treatment plan that can be correlated to a clinically-based figure of merit. The accuracy of the neural net in scoring plans compares well with the reproducibility of the clinical scoring. The system of radiotherapy treatment plan evaluation using an artificial neural network demonstrates promise as a method for generating a clinically relevant figure of merit

  7. Patient-specific dosimetric endpoints based treatment plan quality control in radiotherapy

    International Nuclear Information System (INIS)

    Song, Ting; Zhou, Linghong; Staub, David; Chen, Mingli; Lu, Weiguo; Tian, Zhen; Jia, Xun; Li, Yongbao; Jiang, Steve B; Gu, Xuejun

    2015-01-01

    In intensity modulated radiotherapy (IMRT), the optimal plan for each patient is specific due to unique patient anatomy. To achieve such a plan, patient-specific dosimetric goals reflecting each patient’s unique anatomy should be defined and adopted in the treatment planning procedure for plan quality control. This study is to develop such a personalized treatment plan quality control tool by predicting patient-specific dosimetric endpoints (DEs). The incorporation of patient specific DEs is realized by a multi-OAR geometry-dosimetry model, capable of predicting optimal DEs based on the individual patient’s geometry. The overall quality of a treatment plan is then judged with a numerical treatment plan quality indicator and characterized as optimal or suboptimal. Taking advantage of clinically available prostate volumetric modulated arc therapy (VMAT) treatment plans, we built and evaluated our proposed plan quality control tool. Using our developed tool, six of twenty evaluated plans were identified as sub-optimal plans. After plan re-optimization, these suboptimal plans achieved better OAR dose sparing without sacrificing the PTV coverage, and the dosimetric endpoints of the re-optimized plans agreed well with the model predicted values, which validate the predictability of the proposed tool. In conclusion, the developed tool is able to accurately predict optimally achievable DEs of multiple OARs, identify suboptimal plans, and guide plan optimization. It is a useful tool for achieving patient-specific treatment plan quality control. (paper)

  8. Radiotherapy physics

    International Nuclear Information System (INIS)

    Chen, G.T.Y.; Collier, J.M.; Lyman, J.T.; Pitluck, S.

    1982-01-01

    The Radiotherapy Physics Group works on the physical and biophysical aspects of charged particle radiotherapy. Our activities include the development of isosurvival beams (beams of uniform biological effect), computerized treatment planning development for charged particle radiotherapy, design of compensation to shape dose distributions, and development of dosimetry techniques to verify planned irradiations in both phantoms and patients

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

    International Nuclear Information System (INIS)

    Lu Wei; Parikh, Parag J.; El Naqa, Issam M.; Nystrom, Michelle M.; Hubenschmidt, James P.; Wahab, Sasha H.; Mutic, Sasa; Singh, Anurag K.; Christensen, Gary E.; Bradley, Jeffrey D.; Low, Daniel A.

    2005-01-01

    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

  10. Long range planning of radiotherapy facilities in the Netherlands

    NARCIS (Netherlands)

    Postma, T.J.B.M.; Terpstra, S.

    2000-01-01

    The subject of this paper is long range planning or policy development for healthcare in the Netherlands. Especially the co-ordinating function of planning will be discussed. In healthcare different actors or stakeholders are involved. Each of these actors may have their own interests, expectations,

  11. A covariant form of the Maxwell's equations in four-dimensional spaces with an arbitrary signature

    International Nuclear Information System (INIS)

    Lukac, I.

    1991-01-01

    The concept of duality in the four-dimensional spaces with the arbitrary constant metric is strictly mathematically formulated. A covariant model for covariant and contravariant bivectors in this space based on three four-dimensional vectors is proposed. 14 refs

  12. Impact of field number and beam angle on functional image-guided lung cancer radiotherapy planning

    Science.gov (United States)

    Tahir, Bilal A.; Bragg, Chris M.; Wild, Jim M.; Swinscoe, James A.; Lawless, Sarah E.; Hart, Kerry A.; Hatton, Matthew Q.; Ireland, Rob H.

    2017-09-01

    To investigate the effect of beam angles and field number on functionally-guided intensity modulated radiotherapy (IMRT) normal lung avoidance treatment plans that incorporate hyperpolarised helium-3 magnetic resonance imaging (3He MRI) ventilation data. Eight non-small cell lung cancer patients had pre-treatment 3He MRI that was registered to inspiration breath-hold radiotherapy planning computed tomography. IMRT plans that minimised the volume of total lung receiving  ⩾20 Gy (V20) were compared with plans that minimised 3He MRI defined functional lung receiving  ⩾20 Gy (fV20). Coplanar IMRT plans using 5-field manually optimised beam angles and 9-field equidistant plans were also evaluated. For each pair of plans, the Wilcoxon signed ranks test was used to compare fV20 and the percentage of planning target volume (PTV) receiving 90% of the prescription dose (PTV90). Incorporation of 3He MRI led to median reductions in fV20 of 1.3% (range: 0.2-9.3% p  =  0.04) and 0.2% (range: 0 to 4.1%; p  =  0.012) for 5- and 9-field arrangements, respectively. There was no clinically significant difference in target coverage. Functionally-guided IMRT plans incorporating hyperpolarised 3He MRI information can reduce the dose received by ventilated lung without comprising PTV coverage. The effect was greater for optimised beam angles rather than uniformly spaced fields.

  13. Evaluation of dosimetric variance in whole breast forward-planned intensity-modulated radiotherapy based on 4DCT and 3DCT

    International Nuclear Information System (INIS)

    Wang Wei; Li Jianbin; Hu Hongguang; Sun Tao; Xu Min; Fan Tingyong; Shao Qian

    2013-01-01

    This study was performed to explore and compare the dosimetric variance caused by respiratory movement in the breast during forward-planned intensity-modulated radiotherapy (IMRT) after breast-conserving surgery. A total of 17 enrolled patients underwent the three-dimensional computed tomography (3DCT) simulation scans followed by four-dimensional computed tomography (4DCT) simulation scans during free breathing. The treatment planning constructed using the 3DCT images was copied and applied to the end expiration (EE) and end inspiration (EI) scans and the dose distributions were calculated separately. CTV volume variance amplitude was very small (11.93±28.64 cm 3 ), and the percentage change of CTV volumes receiving 50 Gy and 55 Gy between different scans were all less than 0.8%. There was no statistically significant difference between EI and EE scans (Z=-0.26, P=0.795). However, significant differences were found when comparing the D mean at 3DCT planning with the EI and EE planning (P=0.010 and 0.019, respectively). The homogeneity index at EI, EE and 3D plannings were 0.139, 0.141 and 0.127, respectively, and significant differences existed between 3D and EI, and between 3D and EE (P=0.001 and 0.006, respectively). The conformal index (CI) increased significantly in 3D treatment planning (0.74±0.07) compared with the EI and EE phase plannings (P=0.005 and 0.005, respectively). The V 30 , V 40 , V 50 and D mean of the ipsilateral lung for EE phase planning were significantly lower than for EI (P=0.001-0.042). There were no significant differences in all the dose-volume histogram (DVH) parameters for the heart among these plannings (P=0.128-0.866). The breast deformation during respiration can be disregarded in whole breast IMRT. 3D treatment planning is sufficient for whole breast forward-planned IMRT on the basis of our DVH analysis, but 4D treatment planning, breath-hold, or respiratory gate may ensure precise delivery of radiation dose. (author)

  14. Development of model plans in three dimensional conformal radiotherapy for brain tumors

    International Nuclear Information System (INIS)

    Pyo, Hongryull; Kim, Gwieon; Keum, Kichang; Chang, Sekyung; Suh, Changok; Lee, Sanghoon

    2002-01-01

    Three dimensional conformal radiotherapy planning is being used widely for the treatment of patients with brain tumor. However, it takes much time to develop an optimal treatment plan, therefore, it is difficult to apply this technique to all patients. To increase the efficiency of this technique, we need to develop standard radiotherapy plans for each site of the brain. Therefore we developed several 3 dimensional conformal radiotherapy plans (3D plans) for tumors at each site of brain, compared them with each other, and with 2 dimensional radiotherapy plans. Finally model plans for each site of the brain were decided. Imaginary tumors, with sizes commonly observed in the clinic, were designed for each site of the brain and drawn on CT images. The planning target volumes (PTVs) were as follows; temporal tumor-5.7 x 8.2 x 7.6 cm, suprasellar tumor-3 x 4 x 4.1 cm, thalamic tumor-3.1 x 5.9 x 3.7 cm, frontoparietal tumor-5.5 x 7 x 5.5 cm, and occipitoparietal tumor-5 x 5.5 x 5 cm. Plans using parallel opposed 2-portals and/or 3 portals including fronto-vertex and 2 lateral fields were developed manually as the conventional 2D plans, and 3D noncoplanar conformal plans were developed using beam's eye view and the automatic block drawing tool. Total tumor dose was 54 Gy for a suprasellar tumor, 59.4 Gy and 72 Gy for the other tumors. All dose plans (including 2D plans) were calculated using 3D plan software. Developed plans were compared with each other using dose-volume histograms (DVH), normal tissue complication probabilities (NTCP) and variable dose statistic values (minimum, maximum and mean dose, D5, V83, V85 and V95). Finally a best radiotherapy plan for each site of brain was selected. 1) Temporal tumor; NTCPs and DVHs of the normal tissue of all 3D plans were superior to 2D plans and this trend was more definite when total dose was escalated to 72 Gy (NTCPs of normal brain 2D plans: 27%, 8% → 3D plans: 1%, 1%). Various dose statistic values did not show any

  15. T2-Weighted 4D Magnetic Resonance Imaging for Application in Magnetic Resonance–Guided Radiotherapy Treatment Planning

    Science.gov (United States)

    Freedman, Joshua N.; Collins, David J.; Bainbridge, Hannah; Rank, Christopher M.; Nill, Simeon; Kachelrieß, Marc; Oelfke, Uwe; Leach, Martin O.; Wetscherek, Andreas

    2017-01-01

    Objectives The aim of this study was to develop and verify a method to obtain good temporal resolution T2-weighted 4-dimensional (4D-T2w) magnetic resonance imaging (MRI) by using motion information from T1-weighted 4D (4D-T1w) MRI, to support treatment planning in MR-guided radiotherapy. Materials and Methods Ten patients with primary non–small cell lung cancer were scanned at 1.5 T axially with a volumetric T2-weighted turbo spin echo sequence gated to exhalation and a volumetric T1-weighted stack-of-stars spoiled gradient echo sequence with golden angle spacing acquired in free breathing. From the latter, 20 respiratory phases were reconstructed using the recently developed 4D joint MoCo-HDTV algorithm based on the self-gating signal obtained from the k-space center. Motion vector fields describing the respiratory cycle were obtained by deformable image registration between the respiratory phases and projected onto the T2-weighted image volume. The resulting 4D-T2w volumes were verified against the 4D-T1w volumes: an edge-detection method was used to measure the diaphragm positions; the locations of anatomical landmarks delineated by a radiation oncologist were compared and normalized mutual information was calculated to evaluate volumetric image similarity. Results High-resolution 4D-T2w MRI was obtained. Respiratory motion was preserved on calculated 4D-T2w MRI, with median diaphragm positions being consistent with less than 6.6 mm (2 voxels) for all patients and less than 3.3 mm (1 voxel) for 9 of 10 patients. Geometrical positions were coherent between 4D-T1w and 4D-T2w MRI as Euclidean distances between all corresponding anatomical landmarks agreed to within 7.6 mm (Euclidean distance of 2 voxels) and were below 3.8 mm (Euclidean distance of 1 voxel) for 355 of 470 pairs of anatomical landmarks. Volumetric image similarity was commensurate between 4D-T1w and 4D-T2w MRI, as mean percentage differences in normalized mutual information (calculated over all

  16. T2-Weighted 4D Magnetic Resonance Imaging for Application in Magnetic Resonance-Guided Radiotherapy Treatment Planning.

    Science.gov (United States)

    Freedman, Joshua N; Collins, David J; Bainbridge, Hannah; Rank, Christopher M; Nill, Simeon; Kachelrieß, Marc; Oelfke, Uwe; Leach, Martin O; Wetscherek, Andreas

    2017-10-01

    The aim of this study was to develop and verify a method to obtain good temporal resolution T2-weighted 4-dimensional (4D-T2w) magnetic resonance imaging (MRI) by using motion information from T1-weighted 4D (4D-T1w) MRI, to support treatment planning in MR-guided radiotherapy. Ten patients with primary non-small cell lung cancer were scanned at 1.5 T axially with a volumetric T2-weighted turbo spin echo sequence gated to exhalation and a volumetric T1-weighted stack-of-stars spoiled gradient echo sequence with golden angle spacing acquired in free breathing. From the latter, 20 respiratory phases were reconstructed using the recently developed 4D joint MoCo-HDTV algorithm based on the self-gating signal obtained from the k-space center. Motion vector fields describing the respiratory cycle were obtained by deformable image registration between the respiratory phases and projected onto the T2-weighted image volume. The resulting 4D-T2w volumes were verified against the 4D-T1w volumes: an edge-detection method was used to measure the diaphragm positions; the locations of anatomical landmarks delineated by a radiation oncologist were compared and normalized mutual information was calculated to evaluate volumetric image similarity. High-resolution 4D-T2w MRI was obtained. Respiratory motion was preserved on calculated 4D-T2w MRI, with median diaphragm positions being consistent with less than 6.6 mm (2 voxels) for all patients and less than 3.3 mm (1 voxel) for 9 of 10 patients. Geometrical positions were coherent between 4D-T1w and 4D-T2w MRI as Euclidean distances between all corresponding anatomical landmarks agreed to within 7.6 mm (Euclidean distance of 2 voxels) and were below 3.8 mm (Euclidean distance of 1 voxel) for 355 of 470 pairs of anatomical landmarks. Volumetric image similarity was commensurate between 4D-T1w and 4D-T2w MRI, as mean percentage differences in normalized mutual information (calculated over all respiratory phases and patients), between

  17. Effect of 3D radiotherapy planning compared to 2D planning within a conventional treatment schedule of advanced lung cancer

    International Nuclear Information System (INIS)

    Schraube, P.; Spahn, U.; Oetzel, D.; Wannenmacher, M.

    2000-01-01

    Background: The effect of 3D radiotherapy planning (3D RTP) in comparison to 2D radiotherapy planning (2D RTP) was evaluated in a usually practiced treatment schedule (starting by v./d. opposing portals, continued with computer-planned portals) for non-small-cell lung cancer. Patients and Methods: In 20 patients with locally advanced non-small-cell lung cancer the computer-planned part of the treatment schedule was calculated 2- and 3-dimensionally. Target volume were the primary tumor, the involved and the electively irradiated mediastinal lymph nodes. The results of the 2D RTP were recalculated 3-dimensionally and the mean doses to target volume and organs at risk were defined. Further, the normal tissue complications were calculated. Results: Under the prerequisite of 44 Gy maximally allowed to the spinal cord and a dose to the reference point of 50 Gy a small, but significant advantage with 2.1 Gy to the target (p=0.004) and a reduction of 3.6 Gy to the heart (p=0.05) was achievable for 3D RTP. The dose to the lungs did not differ significantly (19.7 Gy for 2D RTP, 20.3 Gy for 3D RTP). The dose to the heart was not estimated critical by NTCP (normal tissue complication probability). The NTCP for the ipsilateral lung was 16.1 and 18.7% for 2D RTP and 3D RTP, respectively. Regarding the simulator-planned ap/pa fields at the start of the radiotherapy the advantage of 3D RTP was further reduced but remained significant. Favorable with respect to the mean lung dose and the NTCP (18.7% NTCP ipsilateral lung for early onset of 3D planned radiotherapy vs 31.7% for late onset of 3D planned radiotherapy) but not significantly measurable is the early start of the treatment by computerized RTP. Conclusion: The main advantage of 3D RTP in treatment of advanced lung cancer is the better coverage of the target volume. A reduction of the mean lung dose cannot be expected. A dose escalation by 3D RTP to target volumes as described here seems not to be possible because of

  18. Feasibility of preference-driven radiotherapy dose treatment planning to support shared decision making in anal cancer

    DEFF Research Database (Denmark)

    Rønde, Heidi S; Wee, Leonard; Pløen, John

    2017-01-01

    PURPOSE/OBJECTIVE: Chemo-radiotherapy is an established primary curative treatment for anal cancer, but clinically equal rationale for different target doses exists. If joint preferences (physician and patient) are used to determine acceptable tradeoffs in radiotherapy treatment planning, multipl...... that preference-informed dose planning is feasible for clinical studies utilizing shared decision making....... dose plans must be simultaneously explored. We quantified the degree to which different toxicity priorities might be incorporated into treatment plan selection, to elucidate the feasible decision space for shared decision making in anal cancer radiotherapy. MATERIAL AND METHODS: Retrospective plans.......7%-points; (0.3; 30.6); p decision space available in anal cancer radiotherapy to incorporate preferences, although tradeoffs are highly patient-dependent. This study demonstrates...

  19. Considerations for using data envelopment analysis for the assessment of radiotherapy treatment plan quality.

    Science.gov (United States)

    Simpson, John; Raith, Andrea; Rouse, Paul; Ehrgott, Matthias

    2017-10-09

    Purpose The operations research method of data envelopment analysis (DEA) shows promise for assessing radiotherapy treatment plan quality. The purpose of this paper is to consider the technical requirements for using DEA for plan assessment. Design/methodology/approach In total, 41 prostate treatment plans were retrospectively analysed using the DEA method. The authors investigate the impact of DEA weight restrictions with reference to the ability to differentiate plan performance at a level of clinical significance. Patient geometry influences plan quality and the authors compare differing approaches for managing patient geometry within the DEA method. Findings The input-oriented DEA method is the method of choice when performing plan analysis using the key undesirable plan metrics as the DEA inputs. When considering multiple inputs, it is necessary to constrain the DEA input weights in order to identify potential plan improvements at a level of clinical significance. All tested approaches for the consideration of patient geometry yielded consistent results. Research limitations/implications This work is based on prostate plans and individual recommendations would therefore need to be validated for other treatment sites. Notwithstanding, the method that requires both optimised DEA weights according to clinical significance and appropriate accounting for patient geometric factors is universally applicable. Practical implications DEA can potentially be used during treatment plan development to guide the planning process or alternatively used retrospectively for treatment plan quality audit. Social implications DEA is independent of the planning system platform and therefore has the potential to be used for multi-institutional quality audit. Originality/value To the authors' knowledge, this is the first published examination of the optimal approach in the use of DEA for radiotherapy treatment plan assessment.

  20. Optimal radiation port arrangements for hepatic tumor using 3-dimensional conformal radiotherapy planning

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ik Jae; Seong, Jin Sil; Shim, Su Jung; Jeong, Kyoung Keun [Yonsei Univ., Seoul (Korea, Republic of); Cho, Kwang Hwan [Sunchunhyang Univ., Buchon (Korea, Republic of)

    2006-12-15

    The purpose of this study was to investigate the optimal beam arrangements for hepatic tumors, according to the location of the hepatic tumor and its relationship to Organs At Risk (OARs). The virtual gross tumor volumes were divided into four groups according to the Couinaud's classification. Several plans were made for each virtual target, and these plans were compared for the Normal Tissue Complication Probabilities (NTCP). For group I, NTCP improved as the number of the beam ports increased. However, plans with more than 5 ports had little advantage. For group II, plans with the beam directions from the anterior side showed better results. Group III contained many OARs near the target, which placed restrictions on the beam-directions. Multi-directional plans yielded a higher dose to the OARs than a simple two-port plan using right anterior oblique and posterior beam (RAO/PA). For group IV, a simple RAO/PA port plan was adequate for protection of remaining liver. NTCP can significantly vary between radiotherapy plans when the location of the tumor and its neighboring OARs are taken into consideration. The results in this study of optimal beam arrangements could be a useful set of guidelines for radiotherapy of hepatic tumors.

  1. A DVH-guided IMRT optimization algorithm for automatic treatment planning and adaptive radiotherapy replanning

    International Nuclear Information System (INIS)

    Zarepisheh, Masoud; Li, Nan; Long, Troy; Romeijn, H. Edwin; Tian, Zhen; Jia, Xun; Jiang, Steve B.

    2014-01-01

    Purpose: To develop a novel algorithm that incorporates prior treatment knowledge into intensity modulated radiation therapy optimization to facilitate automatic treatment planning and adaptive radiotherapy (ART) replanning. Methods: The algorithm automatically creates a treatment plan guided by the DVH curves of a reference plan that contains information on the clinician-approved dose-volume trade-offs among different targets/organs and among different portions of a DVH curve for an organ. In ART, the reference plan is the initial plan for the same patient, while for automatic treatment planning the reference plan is selected from a library of clinically approved and delivered plans of previously treated patients with similar medical conditions and geometry. The proposed algorithm employs a voxel-based optimization model and navigates the large voxel-based Pareto surface. The voxel weights are iteratively adjusted to approach a plan that is similar to the reference plan in terms of the DVHs. If the reference plan is feasible but not Pareto optimal, the algorithm generates a Pareto optimal plan with the DVHs better than the reference ones. If the reference plan is too restricting for the new geometry, the algorithm generates a Pareto plan with DVHs close to the reference ones. In both cases, the new plans have similar DVH trade-offs as the reference plans. Results: The algorithm was tested using three patient cases and found to be able to automatically adjust the voxel-weighting factors in order to generate a Pareto plan with similar DVH trade-offs as the reference plan. The algorithm has also been implemented on a GPU for high efficiency. Conclusions: A novel prior-knowledge-based optimization algorithm has been developed that automatically adjust the voxel weights and generate a clinical optimal plan at high efficiency. It is found that the new algorithm can significantly improve the plan quality and planning efficiency in ART replanning and automatic treatment

  2. Comparison between conventional and three-dimensional conformal treatment planning for radiotherapy of cerebral tumors

    International Nuclear Information System (INIS)

    Caudrelier, J.M.; Auliard, A.; Sarrazin, T.; Gibon, D.; Coche-Dequeant, B.; Castelain, B.

    2001-01-01

    Comparison between conventional and three-dimensional conformal treatment planning for radiotherapy of cerebral tumors. Purpose. - We prospectively compared a conventional treatment planning (PT2D) and 3-dimensional conformal treatment planning (PT3D) for radiotherapy of cerebral tumours. Patients and methods.- Patients treated between 1/10/98 and 1/4/99 by irradiation for cerebral tumours were analysed. For each case, we planned PT2D using conventional orthogonal x-ray films, and afterward, PT3D using CT scan. Gross tumor volume, planning target volume and normal tissue volumes were defined. Dose was prescribed according to report 50 of the International Commission on Radiation Units and Measurements (ICRU). We compared surfaces of sagittal view targets defined on PT2D and PT3D and called them S2D and S3D, respectively. Irradiated volumes by 90% isodoses (VE-90%) and normal tissue volumes irradiated by 20, 50, 90% isodoses were calculated and compared using Student's paired t-test. Results. -There was a concordance of 84% of target surfaces defined on PT2D and PT3D. Percentages of target surface under- or-over defined by PT2D were 16 and 13% respectively. VE-90% was decreased by 15% (p = 0.07) with PT3D. Normal brain volume irradiated by 90% isodose was decreased by 27% with PT3D (p = 0.04). Conclusion.- For radiotherapy of cerebral tumors using only coplanar beams, PT3D leads to a reduction of normal brain tissue irradiated. We recommend PT3D for radiotherapy of cerebral tumors, particularly for low-grade or benign tumors (meningiomas, neuromas, etc.). (authors)

  3. Treatment planning for radiotherapy with very high-energy electron beams and comparison of VHEE and VMAT plans

    International Nuclear Information System (INIS)

    Bazalova-Carter, Magdalena; Qu, Bradley; Palma, Bianey; Jensen, Christopher; Maxim, Peter G.; Loo, Billy W.; Hårdemark, Björn; Hynning, Elin

    2015-01-01

    Purpose: The aim of this work was to develop a treatment planning workflow for rapid radiotherapy delivered with very high-energy electron (VHEE) scanning pencil beams of 60–120 MeV and to study VHEE plans as a function of VHEE treatment parameters. Additionally, VHEE plans were compared to clinical state-of-the-art volumetric modulated arc therapy (VMAT) photon plans for three cases. Methods: VHEE radiotherapy treatment planning was performed by linking EGSnrc Monte Carlo (MC) dose calculations with inverse treatment planning in a research version of RayStation. In order to study the effect of VHEE treatment parameters on VHEE dose distributions, a MATLAB graphical user interface (GUI) for calculation of VHEE MC pencil beam doses was developed. Through the GUI, pediatric case MC simulations were run for a number of beam energies (60, 80, 100, and 120 MeV), number of beams (13, 17, and 36), pencil beam spot (0.1, 1.0, and 3.0 mm) and grid (2.0, 2.5, and 3.5 mm) sizes, and source-to-axis distance, SAD (40 and 50 cm). VHEE plans for the pediatric case calculated with the different treatment parameters were optimized and compared. Furthermore, 100 MeV VHEE plans for the pediatric case, a lung, and a prostate case were calculated and compared to the clinically delivered VMAT plans. All plans were normalized such that the 100% isodose line covered 95% of the target volume. Results: VHEE beam energy had the largest effect on the quality of dose distributions of the pediatric case. For the same target dose, the mean doses to organs at risk (OARs) decreased by 5%–16% when planned with 100 MeV compared to 60 MeV, but there was no further improvement in the 120 MeV plan. VHEE plans calculated with 36 beams outperformed plans calculated with 13 and 17 beams, but to a more modest degree (<8%). While pencil beam spacing and SAD had a small effect on VHEE dose distributions, 0.1–3 mm pencil beam sizes resulted in identical dose distributions. For the 100 MeV VHEE pediatric

  4. Implementation of three dimensional treatment planning system for external radiotherapy

    International Nuclear Information System (INIS)

    Major, Tibor; Kurup, P.G.G.; Stumpf, Janos

    1997-01-01

    A three dimensional (3D) treatment planning system was installed at Apollo Cancer Hospital, Chennai, India in 1995. This paper gives a short description of the system including hardware components, calculation algorithm, measured data requirements and specific three dimensional features. The concept and the structure of the system are shortly described. The first impressions along with critical opinions and the experiences are gained during the data acquisition are mentioned. Some improvements in the user interface are suggested. It is emphasized that although a 3D system offers more detailed and accurate dose distributions compared to a 2D system, it also introduces a greatly increased workload for the planning staff. (author)

  5. A clinical distance measure for evaluating treatment plan quality difference with Pareto fronts in radiotherapy

    Directory of Open Access Journals (Sweden)

    Kristoffer Petersson

    2017-07-01

    Full Text Available We present a clinical distance measure for Pareto front evaluation studies in radiotherapy, which we show strongly correlates (r = 0.74 and 0.90 with clinical plan quality evaluation. For five prostate cases, sub-optimal treatment plans located at a clinical distance value of >0.32 (0.28–0.35 from fronts of Pareto optimal plans, were assessed to be of lower plan quality by our (12 observers (p < .05. In conclusion, the clinical distance measure can be used to determine if the difference between a front and a given plan (or between different fronts corresponds to a clinically significant plan quality difference.

  6. Improving bladder cancer treatment with radiotherapy using separate intensity modulated radiotherapy plans for boost and elective fields

    Energy Technology Data Exchange (ETDEWEB)

    Van Rooijen, D.; Van de Kamer, J.; Hulshof, M.; Koning, C.; Bel, A. [Department of Radiation Oncology, Academic Medical Center, Amsterdam (Netherlands)

    2010-06-01

    The aim of this study is to investigate to what extent IMRT can decrease the dose to the organs at risk in bladder cancer treatment compared with conformal treatment while making separate treatment plans for the elective field and the boost. Special attention is paid to sparing small intestines. Twenty patients who were treated with the field-in-field technique (FiF) were re-planned with intensity modulated radiotherapy (IMRT) using five and seven beams, respectively. Separate treatment plans were made for the elective field (including the pelvic lymph nodes) and the boost, which enables position correction for bone and tumour separately. The prescribed dose was 40 Gy to the elective field and 55 or 60 Gy to the planning target volume (PTV). For bladder and rectum, V{sub 45}Gy and V{sub 55}Gy were compared, and for small intestines, V{sub 25}Gy and V{sub 40}Gy. The dose distribution with IMRT conformed better to the shape of the target. There was no significant difference between the techniques in dose to the healthy bladder. The median V{sub 40}Gy of the small intestines decreased from 114 to 66 cc (P = 0.001) with five beam IMRT, and to 55 cc (P = 0.001) with seven beam IMRT compared with FiF. V{sub 45}Gy for rectum decreased from 34.2% to 17.5% (P = 0.004) for both five and seven beam plans, while V{sub 55}Gy for rectum remained the same. With IMRT, a statistically significant dose decrease to the small intestines can be achieved while covering both tumour and elective PTV adequately.

  7. Improving bladder cancer treatment with radiotherapy using separate intensity modulated radiotherapy plans for boost and elective fields

    International Nuclear Information System (INIS)

    Van Rooijen, D.; Van de Kamer, J.; Hulshof, M.; Koning, C.; Bel, A.

    2010-01-01

    The aim of this study is to investigate to what extent IMRT can decrease the dose to the organs at risk in bladder cancer treatment compared with conformal treatment while making separate treatment plans for the elective field and the boost. Special attention is paid to sparing small intestines. Twenty patients who were treated with the field-in-field technique (FiF) were re-planned with intensity modulated radiotherapy (IMRT) using five and seven beams, respectively. Separate treatment plans were made for the elective field (including the pelvic lymph nodes) and the boost, which enables position correction for bone and tumour separately. The prescribed dose was 40 Gy to the elective field and 55 or 60 Gy to the planning target volume (PTV). For bladder and rectum, V 45 Gy and V 55 Gy were compared, and for small intestines, V 25 Gy and V 40 Gy. The dose distribution with IMRT conformed better to the shape of the target. There was no significant difference between the techniques in dose to the healthy bladder. The median V 40 Gy of the small intestines decreased from 114 to 66 cc (P = 0.001) with five beam IMRT, and to 55 cc (P = 0.001) with seven beam IMRT compared with FiF. V 45 Gy for rectum decreased from 34.2% to 17.5% (P = 0.004) for both five and seven beam plans, while V 55 Gy for rectum remained the same. With IMRT, a statistically significant dose decrease to the small intestines can be achieved while covering both tumour and elective PTV adequately.

  8. Modeling of a planning system in radiotherapy and Nuclear Medicine using the MCNP6 code

    International Nuclear Information System (INIS)

    Massicano, Felipe

    2015-01-01

    Cancer therapy has many branches and one of them is the use of radiation sources as treatment leading method. Radiotherapy and nuclear medicine are examples of these treatment types. For using the ionization radiation as main tool for the therapy, there is the need of crafting many treatment simulation in order to maximum the tumoral tissue dose without surpass the dose limit in health tissue surrounding. Treatment planning systems (TPS) are systems which have the purpose of simulating these therapy types. Nuclear medicine and radiotherapy have many distinct features linked to the therapy mode and consequently they have different TPS destined for each. The radiotherapy TPS is more developed than the nuclear medicine TPS and by that reason the development of a TPS that was similar to the radiotherapy TPS, but enough generic for include other therapy types, it will contribute with significant advances in nuclear medicine and in others therapy types with radiation. Based on this, the goal of work was to model a TPS that utilizes the Monte Carlo N-Particle Transport code (MCNP6) in order to simulate radiotherapy therapy, nuclear medicine therapy and with potential for simulating other therapy types too. The result of this work was the creation of a Framework in Java language, object oriented, named IBMC which will assist in the development of new TPS with MCNP6 code. The IBMC allowed to develop rapidly and easily TPS for radiotherapy and nuclear medicine and the results were validated with systems already consolidated. The IBMC showed high potential for developing TPS by new therapy types. (author)

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

    International Nuclear Information System (INIS)

    Tian, Bing; Xu, Bing; Lu, Jianping; Liu, Qi; Wang, Li; Wang, Minjie

    2015-01-01

    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

  10. A case study of radiotherapy planning for a bilateral metal hip prosthesis prostate cancer patient

    International Nuclear Information System (INIS)

    Su, Andy; Reft, Chester; Rash, Carla; Price, Jennifer; Jani, Ashesh B.

    2005-01-01

    The purpose of this report is to communicate the observed advantage of intensity-modulated radiotherapy (IMRT) in a patient with bilateral metallic hip prostheses. In this patient with early-stage low-risk disease, a dose of 74 Gy was planned in two phases-an initial 50 Gy to the prostate and seminal vesicles and an additional 24 Gy to the prostate alone. Each coplanar beam avoided the prosthesis in the beam's eye view. Using the same target expansions for each phase, IMRT and 3D-conformal radiotherapy (CRT) plans were compared for target coverage and inhomogeneity as well as dose to the bladder and rectum. The results of the analysis demonstrated that IMRT provided superior target coverage with reduced dose to normal tissues for both individual phases of the treatment plan as well as for the composite treatment plan. The dose to the rectum was significantly reduced with the IMRT technique, with a composite V80 of 35% for the IMRT plan versus 70% for 3D-CRT plan. Similarly, the dose to the bladder was significantly reduced with a V80 of 9% versus 20%. Overall, various dosimetric parameters revealed the corresponding 3D-CRT plan would not have been acceptable. The results indicate significant success with IMRT in a clinical scenario where there were no curative alternatives for local treatment other than external beam radiotherapy. Therefore, definitive external beam radiation of prostate cancer patients with bilateral prosthesis is made feasible with IMRT. The work described herein may also have applicability to other groups of patients, such as those with gynecological or other pelvic malignancies

  11. Operations research for resource planning and -use in radiotherapy: a literature review

    OpenAIRE

    Vieira, Bruno; Hans, Erwin W.; van Vliet-Vroegindeweij, Corine; van de Kamer, Jeroen; van Harten, Wim

    2016-01-01

    Background The delivery of radiotherapy (RT) involves the use of rather expensive resources and multi-disciplinary staff. As the number of cancer patients receiving RT increases, timely delivery becomes increasingly difficult due to the complexities related to, among others, variable patient inflow, complex patient routing, and the joint planning of multiple resources. Operations research (OR) methods have been successfully applied to solve many logistics problems through the development of a...

  12. A new methodological approach for PET implementation in radiotherapy treatment planning.

    Science.gov (United States)

    Bellan, Elena; Ferretti, Alice; Capirci, Carlo; Grassetto, Gaia; Gava, Marcello; Chondrogiannis, Sotirios; Virdis, Graziella; Marzola, Maria Cristina; Massaro, Arianna; Rubello, Domenico; Nibale, Otello

    2012-05-01

    In this paper, a new methodological approach to using PET information in radiotherapy treatment planning has been discussed. Computed tomography (CT) represents the primary modality to plan personalized radiation treatment, because it provides the basic electron density map for correct dose calculation. If PET scanning is also performed it is typically coregistered with the CT study. This operation can be executed automatically by a hybrid PET/CT scanner or, if the PET and CT imaging sets have been acquired through different equipment, by a dedicated module of the radiotherapy treatment planning system. Both approaches have some disadvantages: in the first case, the bore of a PET/CT system generally used in clinical practice often does not allow the use of certain bulky devices for patient immobilization in radiotherapy, whereas in the second case the result could be affected by limitations in window/level visualization of two different image modalities, and the displayed PET volumes can appear not to be related to the actual uptake into the patient. To overcome these problems, at our centre a specific procedure has been studied and tested in 30 patients, allowing good results of precision in the target contouring to be obtained. The process consists of segmentation of the biological target volume by a dedicated PET/CT console and its export to a dedicated radiotherapy system, where an image registration between the CT images acquired by the PET/CT scanner and a large-bore CT is performed. The planning target volume is contoured only on the large-bore CT and is used for virtual simulation, to individuate permanent skin markers on the patient.

  13. Contribution of PET–CT in radiotherapy planning of oesophageal carcinoma: A review

    International Nuclear Information System (INIS)

    Cheung, Gabriel Sai Man

    2013-01-01

    Purpose: The aim of this study was to systematically review published data on the efficacy of positron emission tomography–computed tomography (PET–CT) in the radiotherapy planning process of patients with oesophageal carcinoma. Methods: A systematic search of the PubMed, CINAHL, Cochrane Library and ScienceDirect databases was performed. The quality of the included studies was appraised using validated assessment tool. Data of the studies were synthesized, compared and evaluated by constructing evidentiary tables. Results: The 37 included studies, comprising a total sample size of 1921 patients, had moderate methodological quality. Overall primary tumour detection rate was 92.7%, and pooling estimate of specificity was 88% (95%CI: 83–91%) for local lymph node metastasis. The pooled studies presented heterogeneity for sensitivity (p < 0.01). The introduction of PET–CT to the radiotherapy planning process has facilitated target volume delineation. A standardized uptake value (SUV) of 2.5 could be used in supplementation to visual assessment by a qualified practitioner. Conclusions: PET–CT has a high specificity but due to its variable sensitivity, information from other clinical investigations should still be sought. Discretion and sound clinical judgment must also be exercised before using the biologic information for radiotherapy planning

  14. Evaluation of mathematical methods and linear programming for optimization of the planning in radiotherapy

    International Nuclear Information System (INIS)

    Fernandes, Marco A.R.; Fernandes, David M.; Florentino, Helenice O.

    2010-01-01

    The work detaches the importance of the use of mathematical tools and computer systems for optimization of the planning in radiotherapy, seeking to the distribution of dose of appropriate radiation in the white volume that provides an ideal therapeutic rate between the tumor cells and the adjacent healthy tissues, extolled in the radiotherapy protocols. Examples of target volumes mathematically modeled are analyzed with the technique of linear programming, comparing the obtained results using the Simplex algorithm with those using the algorithm of Interior Points. The System Genesis II was used for obtaining of the isodose curves for the outline and geometry of fields idealized in the computer simulations, considering the parameters of a 10 MV photons beams. Both programming methods (Simplex and Interior Points) they resulted in a distribution of integral dose in the tumor volume and allow the adaptation of the dose in the critical organs inside of the restriction limits extolled. The choice of an or other method should take into account the facility and the need of limiting the programming time. The isodose curves, obtained with the Genesis II System, illustrate that the adjacent healthy tissues to the tumor receives larger doses than those reached in the computer simulations. More coincident values can be obtained altering the weights and some factors of minimization of the objective function. The prohibitive costs of the computer planning systems, at present available for radiotherapy, it motivates the researches to look for the implementation of simpler and so effective methods for optimization of the treatment plan. (author)

  15. Optimization in radiotherapy treatment planning thanks to a fast dose calculation method

    International Nuclear Information System (INIS)

    Yang, Mingchao

    2014-01-01

    This thesis deals with the radiotherapy treatments planning issue which need a fast and reliable treatment planning system (TPS). The TPS is composed of a dose calculation algorithm and an optimization method. The objective is to design a plan to deliver the dose to the tumor while preserving the surrounding healthy and sensitive tissues. The treatment planning aims to determine the best suited radiation parameters for each patient's treatment. In this thesis, the parameters of treatment with IMRT (Intensity modulated radiation therapy) are the beam angle and the beam intensity. The objective function is multi-criteria with linear constraints. The main objective of this thesis is to demonstrate the feasibility of a treatment planning optimization method based on a fast dose-calculation technique developed by (Blanpain, 2009). This technique proposes to compute the dose by segmenting the patient's phantom into homogeneous meshes. The dose computation is divided into two steps. The first step impacts the meshes: projections and weights are set according to physical and geometrical criteria. The second step impacts the voxels: the dose is computed by evaluating the functions previously associated to their mesh. A reformulation of this technique makes possible to solve the optimization problem by the gradient descent algorithm. The main advantage of this method is that the beam angle parameters could be optimized continuously in 3 dimensions. The obtained results in this thesis offer many opportunities in the field of radiotherapy treatment planning optimization. (author) [fr

  16. Automated Planning of Tangential Breast Intensity-Modulated Radiotherapy Using Heuristic Optimization

    International Nuclear Information System (INIS)

    Purdie, Thomas G.; Dinniwell, Robert E.; Letourneau, Daniel; Hill, Christine; Sharpe, Michael B.

    2011-01-01

    Purpose: To present an automated technique for two-field tangential breast intensity-modulated radiotherapy (IMRT) treatment planning. Method and Materials: A total of 158 planned patients with Stage 0, I, and II breast cancer treated using whole-breast IMRT were retrospectively replanned using automated treatment planning tools. The tools developed are integrated into the existing clinical treatment planning system (Pinnacle 3 ) and are designed to perform the manual volume delineation, beam placement, and IMRT treatment planning steps carried out by the treatment planning radiation therapist. The automated algorithm, using only the radio-opaque markers placed at CT simulation as inputs, optimizes the tangential beam parameters to geometrically minimize the amount of lung and heart treated while covering the whole-breast volume. The IMRT parameters are optimized according to the automatically delineated whole-breast volume. Results: The mean time to generate a complete treatment plan was 6 min, 50 s ± 1 min 12 s. For the automated plans, 157 of 158 plans (99%) were deemed clinically acceptable, and 138 of 158 plans (87%) were deemed clinically improved or equal to the corresponding clinical plan when reviewed in a randomized, double-blinded study by one experienced breast radiation oncologist. In addition, overall the automated plans were dosimetrically equivalent to the clinical plans when scored for target coverage and lung and heart doses. Conclusion: We have developed robust and efficient automated tools for fully inversed planned tangential breast IMRT planning that can be readily integrated into clinical practice. The tools produce clinically acceptable plans using only the common anatomic landmarks from the CT simulation process as an input. We anticipate the tools will improve patient access to high-quality IMRT treatment by simplifying the planning process and will reduce the effort and cost of incorporating more advanced planning into clinical practice.

  17. Treatment planning for heavy ion radiotherapy: calculation and optimization of biologically effective dose

    International Nuclear Information System (INIS)

    Kraemer, M.; Scholz, M.

    2000-09-01

    We describe a novel approach to treatment planning for heavy ion radiotherapy based on the local effect model (LEM) which allows to calculate the biologically effective dose not only for the target region but for the entire irradiation volume. LEM is ideally suited to be used as an integral part of treatment planning code systems for active dose shaping devices like the GSI raster scan system. Thus, it has been incorporated into our standard treatment planning system for ion therapy (TRiP). Single intensity modulated fields can be optimized with respect to homogeneous biologically effective dose. The relative biological effectiveness (RBE) is calculated separately for each voxel of the patient CT. Our radiobiologically oriented code system is in use since 1995 for the planning of irradiation experiments with cell cultures and animals such as rats and minipigs. Since 1997 it is in regular and successful use for patient treatment planning. (orig.)

  18. Lung cancer: Value of computed tomography in radiotherapy planning and evaluation of tumour remission

    International Nuclear Information System (INIS)

    Feyerabend, T.; Schmitt, R.; Richter, E.; Bohndorf, W.

    1990-01-01

    434 CT examinations of 133 patients with histologically proven bronchogenic carcinoma (22 out of 133 with small cell lung cancer) were analysed before and after radiotherapy. The study evaluates the use of CT for determining target volume, tumour volume and remission rate: 1. Concerning determination of target volume conventional roentgendiagnostic simulator methods are much inferior to CT aided planning; as for our patients changes of the target volume were necessary in 50%, in 22% the changes were crucial. This happened more often in non-small cell lung cancer than in small cell carcinomas. 2. The response rate (CR + PR) after radiotherapy (based on the calculated tumour volumes by CT) was 70 to 80%. The rate of CR of the primary was 45% (non-small cell carcinoma) and 67% (small cell carcinoma). 3. The crucial point for the evaluation of tumour remission after radiotherapy is the point of time. One to three months and four to nine months after irradiation we found complete remissions in 19% and 62%, respectively. Hence, the evaluation of treatment results earlier than three months after radiotherapy may be incorrect. We deem it indispensable to use CT for determination of target, calculation of dose distribution and accurate evaluation of tumour remission and side effects during and after irradiation of patients with bronchogenic carcinoma. (orig.) [de

  19. A review of plan library approaches in adaptive radiotherapy of bladder cancer.

    Science.gov (United States)

    Collins, Shane D; Leech, Michelle M

    2018-05-01

    Large variations in the shape and size of the bladder volume are commonly observed in bladder cancer radiotherapy (RT). The clinical target volume (CTV) is therefore frequently inadequately treated and large isotropic margins are inappropriate in terms of dose to organs at risk (OAR); thereby making adaptive radiotherapy (ART) attractive for this tumour site. There are various methods of ART delivery, however, for bladder cancer, plan libraries are frequently used. A review of published studies on plan libraries for bladder cancer using four databases (Pubmed, Science Direct, Embase and Cochrane Library) was conducted. The endpoints selected were accuracy and feasibility of initiation of a plan library strategy into a RT department. Twenty-four articles were included in this review. The majority of studies reported improvement in accuracy with 10 studies showing an improvement in planning target volume (PTV) and CTV coverage with plan libraries, some by up to 24%. Seventeen studies showed a dose reduction to OARs, particularly the small bowel V45Gy, V40Gy, V30Gy and V10Gy, and the rectal V30Gy. However, the occurrence of no suitable plan was reported in six studies, with three studies showing no significant difference between adaptive and non-adaptive strategies in terms of target coverage. In addition, inter-observer variability in plan selection appears to remain problematic. The additional resources, education and technology required for the initiation of plan library selection for bladder cancer may hinder its routine clinical implementation, with eight studies illustrating increased treatment time required. While there is a growing body of evidence in support of plan libraries for bladder RT, many studies differed in their delivery approach. The advent of the clinical use of the MRI-linear accelerator will provide RT departments with the opportunity to consider daily online adaption for bladder cancer as an alternate to plan library approaches.

  20. Treatment planning evaluation of non-coplanar techniques for conformal radiotherapy of the prostate

    International Nuclear Information System (INIS)

    Bedford, James L.; Henrys, Anthony J.; Dearnaley, David P.; Khoo, Vincent S.

    2005-01-01

    Background and purpose: To evaluate the benefit of using non-coplanar treatment plans for irradiation of two different clinical treatment volumes: prostate only (PO) and the prostate plus seminal vesicles (PSV). Material and methods: An inverse planning algorithm was used to produce three-field, four-field, five-field and six-field non-coplanar treatment plans without intensity-modulation in ten patients. These were compared against a three-field coplanar plan. A dose of 74 Gy was prescribed to the isocentre. Plans were compared using the minimum dose to the planning target volume (PTV), maximum dose to the small bowel, and irradiated volumes of rectum, bladder and femoral head. Biological indices were also evaluated. Results: For the PO group, volume of rectum irradiated to 60 Gy (V 60 ) was 22.5±3.7% for the coplanar plan, and 21.5±5.3% for the five-field non-coplanar plan, which was the most beneficial (p=0.3). For the PSV group, the five-field non-coplanar plan was again the most beneficial. Rectal V 60 was in this case reduced from 41.5±10.4% for the coplanar plan to 35.2±9.3% for the non-coplanar plan (p=0.02). Conclusions: The use of non-coplanar beams in conformal prostate radiotherapy provides a small increase in rectal sparing, more significantly with PSV volumes than for PO volumes

  1. Comment on non-renormalization theorem in the four dimensional superstrings

    International Nuclear Information System (INIS)

    Soda, Jiro; Nakazawa, Naohito; Sakai, Kenji; Ojima, Shuichi.

    1987-10-01

    We discuss non-renormalization theorem in the context of the four dimensional superstrings. We explicitly demonstrate that the graviton 3-point one-loop amplitude does not vanish in contrast to the ten dimensional superstring theories. (author)

  2. Four-Dimensional Ultrafast Electron Microscopy: Insights into an Emerging Technique

    KAUST Repository

    Adhikari, Aniruddha; Eliason, Jeffrey K.; Sun, Jingya; Bose, Riya; Flannigan, David J.; Mohammed, Omar F.

    2016-01-01

    Four-dimensional ultrafast electron microscopy (4D-UEM) is a novel analytical technique that aims to fulfill the long-held dream of researchers to investigate materials at extremely short spatial and temporal resolutions by integrating the excellent

  3. A Multiplan Treatment-Planning Framework: A Paradigm Shift for Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Meyer, Robert R.; Zhang, Hao H.; Goadrich, Laura; Nazareth, Daryl P.; Shi Leyuan; D'Souza, Warren D.

    2007-01-01

    Purpose: To describe a multiplan intensity-modulated radiotherapy (IMRT) planning framework, and to describe a decision support system (DSS) for ranking multiple plans and modeling the planning surface. Methods and Materials: One hundred twenty-five plans were generated sequentially for a head-and-neck case and a pelvic case by varying the dose-volume constraints on each of the organs at risk (OARs). A DSS was used to rank plans according to dose-volume histogram (DVH) values, as well as equivalent uniform dose (EUD) values. Two methods for ranking treatment plans were evaluated: composite criteria and pre-emptive selection. The planning surface determined by the results was modeled using quadratic functions. Results: The DSS provided an easy-to-use interface for the comparison of multiple plan features. Plan ranking resulted in the identification of one to three 'optimal' plans. The planning surface models had good predictive capability with respect to both DVH values and EUD values and generally, errors of <6%. Models generated by minimizing the maximum relative error had significantly lower relative errors than models obtained by minimizing the sum of squared errors. Using the quadratic model, plan properties for one OAR were determined as a function of the other OAR constraint settings. The modeled plan surface can then be used to understand the interdependence of competing planning objectives. Conclusion: The DSS can be used to aid the planner in the selection of the most desirable plan. The collection of quadratic models constructed from the plan data to predict DVH and EUD values generally showed excellent agreement with the actual plan values

  4. Experimental evaluations of the accuracy of 3D and 4D planning in robotic tracking stereotactic body radiotherapy for lung cancers

    International Nuclear Information System (INIS)

    Chan, Mark K. H.; Kwong, Dora L. W.; Ng, Sherry C. Y.; Tong, Anthony S. M.; Tam, Eric K. W.

    2013-01-01

    Purpose: Due to the complexity of 4D target tracking radiotherapy, the accuracy of this treatment strategy should be experimentally validated against established standard 3D technique. This work compared the accuracy of 3D and 4D dose calculations in respiration tracking stereotactic body radiotherapy (SBRT). Methods: Using the 4D planning module of the CyberKnife treatment planning system, treatment plans for a moving target and a static off-target cord structure were created on different four-dimensional computed tomography (4D-CT) datasets of a thorax phantom moving in different ranges. The 4D planning system used B-splines deformable image registrations (DIR) to accumulate dose distributions calculated on different breathing geometries, each corresponding to a static 3D-CT image of the 4D-CT dataset, onto a reference image to compose a 4D dose distribution. For each motion, 4D optimization was performed to generate a 4D treatment plan of the moving target. For comparison with standard 3D planning, each 4D plan was copied to the reference end-exhale images and a standard 3D dose calculation was followed. Treatment plans of the off-target structure were first obtained by standard 3D optimization on the end-exhale images. Subsequently, they were applied to recalculate the 4D dose distributions using DIRs. All dose distributions that were initially obtained using the ray-tracing algorithm with equivalent path-length heterogeneity correction (3D EPL and 4D EPL ) were recalculated by a Monte Carlo algorithm (3D MC and 4D MC ) to further investigate the effects of dose calculation algorithms. The calculated 3D EPL , 3D MC , 4D EPL , and 4D MC dose distributions were compared to measurements by Gafchromic EBT2 films in the axial and coronal planes of the moving target object, and the coronal plane for the static off-target object based on the γ metric at 5%/3mm criteria (γ 5%/3mm ). Treatment plans were considered acceptable if the percentage of pixels passing γ 5

  5. Ultra high speed optical transmission using subcarrier-multiplexed four-dimensional LDPC-coded modulation.

    Science.gov (United States)

    Batshon, Hussam G; Djordjevic, Ivan; Schmidt, Ted

    2010-09-13

    We propose a subcarrier-multiplexed four-dimensional LDPC bit-interleaved coded modulation scheme that is capable of achieving beyond 480 Gb/s single-channel transmission rate over optical channels. Subcarrier-multiplexed four-dimensional LDPC coded modulation scheme outperforms the corresponding dual polarization schemes by up to 4.6 dB in OSNR at BER 10(-8).

  6. Four-dimensional Hall mechanics as a particle on CP3

    International Nuclear Information System (INIS)

    Bellucci, Stefano; Casteill, Pierre-Yves; Nersessian, Armen

    2003-01-01

    In order to establish an explicit connection between four-dimensional Hall effect on S 4 and six-dimensional Hall effect on CP 3 , we perform the Hamiltonian reduction of a particle moving on CP 3 in a constant magnetic field to the four-dimensional Hall mechanics (i.e., a-bar particle on S 4 in a SU(2) instanton field). This reduction corresponds to fixing the isospin of the latter system

  7. Hawking radiation from four-dimensional Schwarzschild black holes in M theory

    International Nuclear Information System (INIS)

    Das, S.R.; Mathur, S.D.; Ramadevi, P.

    1999-01-01

    Recently a method has been developed for relating four dimensional Schwarzschild black holes in M theory to near-extremal black holes in string theory with four charges, using suitably defined open-quotes boostsclose quotes and T dualities. We show that this method can be extended to obtain the emission rate of low energy massless scalars for the four dimensional Schwarzschild hole from the microscopic picture of radiation from the near extremal hole. copyright 1999 The American Physical Society

  8. (18) F-FDG PET/CT for planning external beam radiotherapy alters therapy in 11% of 581 patients

    DEFF Research Database (Denmark)

    Birk Christensen, Charlotte; Loft-Jakobsen, Annika; Munck Af Rosenschöld, Per

    2018-01-01

    BACKGROUND: (18) F-FDG PET/CT (FDG PET/CT) used in radiotherapy planning for extra-cerebral malignancy may reveal metastases to distant sites that may affect the choice of therapy. AIM: To investigate the role of FDG PET/CT on treatment strategy changes induced by the use of PET/CT as part...... planning in our institution in the year 2008. All PET/CT scans were performed with the patient in treatment position with the use of immobilization devices according to the intended radiotherapy treatment. All scans were evaluated by a nuclear medicine physician together with a radiologist to delineate PET......% of the patients for whom the PET/CT simulation scan revealed unexpected dissemination, radiotherapy was given - changed (n = 38) or unchanged (n = 13) according to the findings on the FDG PET/CT. CONCLUSION: Unexpected dissemination on the FDG PET/CT scanning performed for radiotherapy planning caused a change...

  9. Implementation of an Analytical Model for Leakage Neutron Equivalent Dose in a Proton Radiotherapy Planning System

    Energy Technology Data Exchange (ETDEWEB)

    Eley, John [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Graduate School of Biomedical Sciences, The University of Texas, 6767 Bertner Ave., Houston, TX 77030 (United States); Newhauser, Wayne, E-mail: newhauser@lsu.edu [Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Tower Drive, Baton Rouge, LA 70803 (United States); Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809 (United States); Homann, Kenneth; Howell, Rebecca [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Graduate School of Biomedical Sciences, The University of Texas, 6767 Bertner Ave., Houston, TX 77030 (United States); Schneider, Christopher [Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Tower Drive, Baton Rouge, LA 70803 (United States); Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809 (United States); Durante, Marco; Bert, Christoph [GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291 (Germany)

    2015-03-11

    Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects.

  10. SU-G-TeP1-05: Development and Clinical Introduction of Automated Radiotherapy Treatment Planning for Prostate Cancer

    International Nuclear Information System (INIS)

    Winkel, D; Bol, GH; Asselen, B van; Hes, J; Scholten, V; Kerkmeijer, LGW; Raaymakers, BW

    2016-01-01

    Purpose: To develop an automated radiotherapy treatment planning and optimization workflow for prostate cancer in order to generate clinical treatment plans. Methods: A fully automated radiotherapy treatment planning and optimization workflow was developed based on the treatment planning system Monaco (Elekta AB, Stockholm, Sweden). To evaluate our method, a retrospective planning study (n=100) was performed on patients treated for prostate cancer with 5 field intensity modulated radiotherapy, receiving a dose of 35×2Gy to the prostate and vesicles and a simultaneous integrated boost of 35×0.2Gy to the prostate only. A comparison was made between the dosimetric values of the automatically and manually generated plans. Operator time to generate a plan and plan efficiency was measured. Results: A comparison of the dosimetric values show that automatically generated plans yield more beneficial dosimetric values. In automatic plans reductions of 43% in the V72Gy of the rectum and 13% in the V72Gy of the bladder are observed when compared to the manually generated plans. Smaller variance in dosimetric values is seen, i.e. the intra- and interplanner variability is decreased. For 97% of the automatically generated plans and 86% of the clinical plans all criteria for target coverage and organs at risk constraints are met. The amount of plan segments and monitor units is reduced by 13% and 9% respectively. Automated planning requires less than one minute of operator time compared to over an hour for manual planning. Conclusion: The automatically generated plans are highly suitable for clinical use. The plans have less variance and a large gain in time efficiency has been achieved. Currently, a pilot study is performed, comparing the preference of the clinician and clinical physicist for the automatic versus manual plan. Future work will include expanding our automated treatment planning method to other tumor sites and develop other automated radiotherapy workflows.

  11. Correction of heterogeneities in the issue compositions in the construction plans optimized in radiotherapy using linear programming

    International Nuclear Information System (INIS)

    Viana, Rodrigo Sartorelo S.; Lima, Ernesto A.B.F.; Florentino, Helenice de Oliveira; Fonseca, Paulo Roberto da; Homem, Thiago Pedro Donadon

    2009-01-01

    Linear programming models are widely found in the literature addressing various aspects involved in the creation of optimized planning for radiotherapy. However, most mathematical formulations does not incorporate certain factors that are of extreme importance for the formulation of a real planning like the attenuation of the beam of radiation and heterogeneity in the composition of tissue irradiated. In this context are proposed in this paper some modifications in the formulation of a linear programming problem with the objective of making the simulation closer to the real planning for radiotherapy and thus enable a more reliable and comprehensive planning requirements. (author)

  12. New horizons with PET/CT in high-tech radiotherapy planning

    International Nuclear Information System (INIS)

    Hadjieva, T.

    2009-01-01

    Full text:The precise delineation of exposed volumes in the high-tech radiotherapy is a major problem. The malignoma imaging was revolutionized by PET. PET became one of the routine imaging methods in developed countries in Europe and USA. PET with 18-FDG, combined with structural and topographic representation of images by CT, currently provides the most reliable information about the location and spread of tumor. Three dimensional radiotherapy planning is a challenge in today's practice and requires the most accurate visualization of the tumor, with its functional characteristics (proliferation activity, hypoxic cells, apoptosis, neoangiogenesis) and surrounding radiosensitive normal tissue and organs. The collected information about the main indications for radiotherapy planning using PET / CT in head and neck cancers , small cell lung carcinoma and some malignant lymphomas has been discussed. The problem of false positive and false negative findings has been also considered. The protocol for 18-FDG PET / CT conducting according to the agreed consensus of the IAEA expert meeting held in 2006 is presented

  13. Gross tumor volume dependency on phase sorting methods of four-dimensional computed tomography images for lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soo Yong; Lim, Sang Wook; Ma, Sun Young; Yu, Je Sang [Dept. of Radiation Oncology, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan (Korea, Republic of)

    2017-09-15

    To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.

  14. Evaluating efficiency of split VMAT plan for prostate cancer radiotherapy involving pelvic lymph nodes

    Energy Technology Data Exchange (ETDEWEB)

    Mun, Jun Ki; Son, Sang Jun; Kim, Dae Ho; Seo, Seok Jin [Dept. of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of)

    2015-12-15

    The purpose of this study is to evaluate the efficiency of Split VMAT planning(Contouring rectum divided into an upper and a lower for reduce rectum dose) compare to Conventional VMAT planning(Contouring whole rectum) for prostate cancer radiotherapy involving pelvic lymph nodes. A total of 9 cases were enrolled. Each case received radiotherapy with Split VMAT planning to the prostate involving pelvic lymph nodes. Treatment was delivered using TrueBeam STX(Varian Medical Systems, USA) and planned on Eclipse(Ver. 10.0.42, Varian, USA), PRO3(Progressive Resolution Optimizer 10.0.28), AAA(Anisotropic Analytic Algorithm Ver. 10.0.28). Lower rectum contour was defined as starting 1 cm superior and ending 1 cm inferior to the prostate PTV, upper rectum is a part, except lower rectum from the whole rectum. Split VMAT plan parameters consisted of 10 MV coplanar 360° arcs. Each arc had 30° and 30° collimator angle, respectively. An SIB(Simultaneous Integrated Boost) treatment prescription was employed delivering 50.4 Gy to pelvic lymph nodes and 63- 70 Gy to the prostate in 28 fractions. D{sub mean} of whole rectum on Split VMAT plan was applied for DVC(Dose Volume Constraint) of the whole rectum for Conventional VMAT plan. In addition, all parameters were set to be the same of existing treatment plans. To minimize the dose difference that shows up randomly on optimizing, all plans were optimized and calculated twice respectively using a 0.2 cm grid. All plans were normalized to the prostate PTV{sub 100%} = 90% or 95%. A comparison of D{sub mean} of whole rectum, upperr ectum, lower rectum, and bladder, V{sub 50%} of upper rectum, total MU and H.I.(Homogeneity Index) and C.I.(Conformity Index) of the PTV was used for technique evaluation. All Split VMAT plans were verified by gamma test with portal dosimetry using EPID. Using DVH analysis, a difference between the Conventional and the Split VMAT plans was demonstrated. The Split VMAT plan demonstrated better in the D

  15. Radiotherapy of prostate cancer with or without intensity modulated beams: a planning comparison

    International Nuclear Information System (INIS)

    Meerleer, Gert O. de; Vakaet, Luc A.M.L.; Gersem, Werner R.T. de; Wagter, Carlos de; Naeyer, Bart de; Neve, Wilfried de

    2000-01-01

    Purpose: To evaluate whether intensity modulated radiotherapy (IMRT) by static segmented beams allows the dose to the main portion of the prostate target to escalate while keeping the maximal dose at the anterior rectal wall at 72 Gy. The value of such IMRT plans was analyzed by comparison with non-IMRT plans using the same beam incidences. Methods and Materials: We performed a planning study on the CT data of 32 consecutive patients with localized adenocarcinoma of the prostate. Three fields in the transverse plane with gantry angles of 0 deg. , 116 deg. , and 244 deg. were isocentered at the center of gravity of the target volume (prostate and seminal vesicles). The geometry of the beams was determined by beam's eye view autocontouring of the target volume with a margin of 1.5 cm. In study 1, the beam weights were determined by a human planner (3D-man) or by computer optimization using a biological objective function with (3D-optim-lim) or without (3D-optim-unlim) a physical term to limit target dose inhomogeneity. In study 2, the 3 beam incidences mentioned above were used and in-field uniform segments were added to allow IMRT. Plans with (IMRT-lim) or without (IMRT-unlim) constraints on target dose inhomogeneity were compared. In the IMRT-lim plan, target dose inhomogeneity was constrained between 15% and 20%. After optimization, plans in both studies were normalized to a maximal rectal dose of 72 Gy. Biological (tumor control probability [TCP], normal tissue complication probability [NTCP]) and physical indices for tumor control and normal tissue complication probabilities were computed, as well as the probability of the uncomplicated local control (P+). Results: The IMRT-lim plan was superior to all other plans concerning TCP (p =no. 89%). For bladder, maximal bladder dose was significantly higher in the IMRT-unlim plan compared to all other plans (p no. <=no. 0.0001). P+ was significantly higher in both IMRT-plans than in all other plans. The 3D

  16. Localization of the prostatic apex for radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Wilder, Richard B.; Fone, Patricia D.; Jones, C. Darryl; White, Ralph DeVere

    1996-01-01

    Purpose/Objective: There is no consensus on the optimal method for localizing the prostatic apex in patients with early stage adenocarcinoma of the prostate. Some radiation oncologists have recommended that transrectal ultrasound or MRI scans be used to define the inferior border of radiation portals. The purpose of this prospective study is to assess the ability of retrograde urethrograms and CT scans to accurately define the prostatic apex in the craniocaudad dimension, using urethroscopy as a reference. Materials and Methods: Following construction of an Alpha cradle, plain radiographs of the pelvis were obtained in 15 patients with early stage adenocarcinoma of the prostate, with the tip of a urethroscope placed at the superior border of the external sphincter (which most closely approximates the prostatic apex). The scope was then withdrawn, and a retrograde urethrogram was performed. Immediately afterwards, a treatment planning CT scan of the pelvis was obtained. Since differential filling of the bladder and rectum affects the position of the prostatic apex, patients voided prior to rather than in between the 3 consecutive studies. Results: The urethroscopy-defined prostatic apex was located 28 ± 3 mm (mean ± SE) superior to the ischial tuberosities, 12 ± 1 mm (mean ± SE) superior to the urethrogram tip and 8 ± 2 mm (mean ± SE) superior to the CT-defined apex. Placement of the inferior border of the radiation portals at the ischial tuberosities would have resulted in irradiation of > 20 mm membranous and spongy urethra in all of the patients. Conclusion: Retrograde urethrograms provide more helpful information than CT scans with regard to localization of the prostatic apex and are more cost effective than sonograms or MRI scans. The prostatic apex is typically 12 mm superior to the urethrogram tip with little variability. Retrograde urethrograms allow one to spare as much urethra as possible in the radiation portals, which should theoretically reduce

  17. Vector-model-supported optimization in volumetric-modulated arc stereotactic radiotherapy planning for brain metastasis

    International Nuclear Information System (INIS)

    Liu, Eva Sau Fan; Wu, Vincent Wing Cheung; Harris, Benjamin; Foote, Matthew; Lehman, Margot; Chan, Lawrence Wing Chi

    2017-01-01

    Long planning time in volumetric-modulated arc stereotactic radiotherapy (VMA-SRT) cases can limit its clinical efficiency and use. A vector model could retrieve previously successful radiotherapy cases that share various common anatomic features with the current case. The prsent study aimed to develop a vector model that could reduce planning time by applying the optimization parameters from those retrieved reference cases. Thirty-six VMA-SRT cases of brain metastasis (gender, male [n = 23], female [n = 13]; age range, 32 to 81 years old) were collected and used as a reference database. Another 10 VMA-SRT cases were planned with both conventional optimization and vector-model-supported optimization, following the oncologists' clinical dose prescriptions. Planning time and plan quality measures were compared using the 2-sided paired Wilcoxon signed rank test with a significance level of 0.05, with positive false discovery rate (pFDR) of less than 0.05. With vector-model-supported optimization, there was a significant reduction in the median planning time, a 40% reduction from 3.7 to 2.2 hours (p = 0.002, pFDR = 0.032), and for the number of iterations, a 30% reduction from 8.5 to 6.0 (p = 0.006, pFDR = 0.047). The quality of plans from both approaches was comparable. From these preliminary results, vector-model-supported optimization can expedite the optimization of VMA-SRT for brain metastasis while maintaining plan quality.

  18. Vector-model-supported optimization in volumetric-modulated arc stereotactic radiotherapy planning for brain metastasis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Eva Sau Fan [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); Department of Health Technology and Informatics, The Hong Kong Polytechnic University (Hong Kong); Wu, Vincent Wing Cheung [Department of Health Technology and Informatics, The Hong Kong Polytechnic University (Hong Kong); Harris, Benjamin [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); Foote, Matthew; Lehman, Margot [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); School of Medicine, University of Queensland (Australia); Chan, Lawrence Wing Chi, E-mail: wing.chi.chan@polyu.edu.hk [Department of Health Technology and Informatics, The Hong Kong Polytechnic University (Hong Kong)

    2017-07-01

    Long planning time in volumetric-modulated arc stereotactic radiotherapy (VMA-SRT) cases can limit its clinical efficiency and use. A vector model could retrieve previously successful radiotherapy cases that share various common anatomic features with the current case. The prsent study aimed to develop a vector model that could reduce planning time by applying the optimization parameters from those retrieved reference cases. Thirty-six VMA-SRT cases of brain metastasis (gender, male [n = 23], female [n = 13]; age range, 32 to 81 years old) were collected and used as a reference database. Another 10 VMA-SRT cases were planned with both conventional optimization and vector-model-supported optimization, following the oncologists' clinical dose prescriptions. Planning time and plan quality measures were compared using the 2-sided paired Wilcoxon signed rank test with a significance level of 0.05, with positive false discovery rate (pFDR) of less than 0.05. With vector-model-supported optimization, there was a significant reduction in the median planning time, a 40% reduction from 3.7 to 2.2 hours (p = 0.002, pFDR = 0.032), and for the number of iterations, a 30% reduction from 8.5 to 6.0 (p = 0.006, pFDR = 0.047). The quality of plans from both approaches was comparable. From these preliminary results, vector-model-supported optimization can expedite the optimization of VMA-SRT for brain metastasis while maintaining plan quality.

  19. How precise is manual CT-MRI registration for cranial radiotherapy planning?

    International Nuclear Information System (INIS)

    Mosleh-Shirazi, M. A.; South, P. C.

    2005-01-01

    Manual fusion is a readily available image registration technique that does not require matching algorithms. The operator performs rigid-body transformations interactively. The precision of Manual fusion (as implemented on the Philips Pinnacle treatment planning system) was required for cranial CT-MR images used in radiotherapy planning for typical centrally located planning target volumes . Materials and Methods: A multi-stage Manual fusion procedure was developed which 11 observers followed to match the head contour, bones, soft tissues and contoured structures for 5 patient image-sets. Registration parameters were calculated by solving the transformation matrix following a consistent order of translations (T) and rotations (R). The mean position of centre of each planning target volumes averaged over all observers was used as the reference. The effect of mis registration on the planning target volumes co-ordinates and the volume increase resulting from application of a margin for registration uncertainty were calculated. Results: Mean intra- and inter-observer T/R SDs were 0.5 mm/ 0.4 d ig a nd 1.1 mm/ 1.0 d ig , respectively. Mean intra- and inter-observer registration error (3D distance of each planning target volumes centre from the mean position for all observers) was 0.7 ±0.3 mm (1 SD) and 1.6±0.7 mm respectively, the latter reducing to 1.4±0.6 mm excluding the 3 least experienced operators. A subsequent 2 mm margin for mis registration on average increased the planning target volume by 27%. Conclusion: Moderately trained operators produced clinically acceptable results while experienced operators improved the precision. Manual fusion still has an important role in the registration of cranial CT and MR images for radiotherapy planning especially for under-resourced centers

  20. Audit of an automated checklist for quality control of radiotherapy treatment plans

    International Nuclear Information System (INIS)

    Breen, Stephen L.; Zhang Beibei

    2010-01-01

    Purpose: To assess the effect of adding an automated checklist to the treatment planning process for head and neck intensity-modulated radiotherapy. Methods: Plans produced within our treatment planning system were evaluated at the planners' discretion with an automated checklist of more than twenty planning parameters. Plans were rated as accepted or rejected for treatment, during regular review by radiation oncologists and physicists as part of our quality control program. The rates of errors and their types were characterised prior to the implementation of the checklist and with the checklist. Results: Without the checklist, 5.9% of plans were rejected; the use of the checklist reduced the rejection rate to 3.1%. The checklist was used for 64.7% of plans. Pareto analysis of the causes of rejection showed that the checklist reduced the number of causes of rejections from twelve to seven. Conclusions: The use of an automated checklist has reduced the need for reworking of treatment plans. With the use of the checklist, most rejections were due to errors in prescription or inadequate dose distributions. Use of the checklist by planners must be increased to maximise improvements in planning efficiency.

  1. Dosimetric benefit of adaptive re-planning in pancreatic cancer stereotactic body radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yongbao [Department of Engineering Physics, Tsinghua University, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing (China); Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Hoisak, Jeremy D.P.; Li, Nan; Jiang, Carrie [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Tian, Zhen [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Gautier, Quentin; Zarepisheh, Masoud [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Wu, Zhaoxia; Liu, Yaqiang [Department of Engineering Physics, Tsinghua University, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing (China); Jia, Xun [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); and others

    2015-01-01

    Stereotactic body radiotherapy (SBRT) shows promise in unresectable pancreatic cancer, though this treatment modality has high rates of normal tissue toxicity. This study explores the dosimetric utility of daily adaptive re-planning with pancreas SBRT. We used a previously developed supercomputing online re-planning environment (SCORE) to re-plan 10 patients with pancreas SBRT. Tumor and normal tissue contours were deformed from treatment planning computed tomographies (CTs) and transferred to daily cone-beam CT (CBCT) scans before re-optimizing each daily treatment plan. We compared the intended radiation dose, the actual radiation dose, and the optimized radiation dose for the pancreas tumor planning target volume (PTV) and the duodenum. Treatment re-optimization improved coverage of the PTV and reduced dose to the duodenum. Within the PTV, the actual hot spot (volume receiving 110% of the prescription dose) decreased from 4.5% to 0.5% after daily adaptive re-planning. Within the duodenum, the volume receiving the prescription dose decreased from 0.9% to 0.3% after re-planning. It is noteworthy that variation in the amount of air within a patient's stomach substantially changed dose to the PTV. Adaptive re-planning with pancreas SBRT has the ability to improve dose to the tumor and decrease dose to the nearby duodenum, thereby reducing the risk of toxicity.

  2. Retrieval with Clustering in a Case-Based Reasoning System for Radiotherapy Treatment Planning

    Science.gov (United States)

    Khussainova, Gulmira; Petrovic, Sanja; Jagannathan, Rupa

    2015-05-01

    Radiotherapy treatment planning aims to deliver a sufficient radiation dose to cancerous tumour cells while sparing healthy organs in the tumour surrounding area. This is a trial and error process highly dependent on the medical staff's experience and knowledge. Case-Based Reasoning (CBR) is an artificial intelligence tool that uses past experiences to solve new problems. A CBR system has been developed to facilitate radiotherapy treatment planning for brain cancer. Given a new patient case the existing CBR system retrieves a similar case from an archive of successfully treated patient cases with the suggested treatment plan. The next step requires adaptation of the retrieved treatment plan to meet the specific demands of the new case. The CBR system was tested by medical physicists for the new patient cases. It was discovered that some of the retrieved cases were not suitable and could not be adapted for the new cases. This motivated us to revise the retrieval mechanism of the existing CBR system by adding a clustering stage that clusters cases based on their tumour positions. A number of well-known clustering methods were investigated and employed in the retrieval mechanism. Results using real world brain cancer patient cases have shown that the success rate of the new CBR retrieval is higher than that of the original system.

  3. Retrieval with Clustering in a Case-Based Reasoning System for Radiotherapy Treatment Planning

    International Nuclear Information System (INIS)

    Khussainova, Gulmira; Petrovic, Sanja; Jagannathan, Rupa

    2015-01-01

    Radiotherapy treatment planning aims to deliver a sufficient radiation dose to cancerous tumour cells while sparing healthy organs in the tumour surrounding area. This is a trial and error process highly dependent on the medical staff's experience and knowledge. Case-Based Reasoning (CBR) is an artificial intelligence tool that uses past experiences to solve new problems. A CBR system has been developed to facilitate radiotherapy treatment planning for brain cancer. Given a new patient case the existing CBR system retrieves a similar case from an archive of successfully treated patient cases with the suggested treatment plan. The next step requires adaptation of the retrieved treatment plan to meet the specific demands of the new case. The CBR system was tested by medical physicists for the new patient cases. It was discovered that some of the retrieved cases were not suitable and could not be adapted for the new cases. This motivated us to revise the retrieval mechanism of the existing CBR system by adding a clustering stage that clusters cases based on their tumour positions. A number of well-known clustering methods were investigated and employed in the retrieval mechanism. Results using real world brain cancer patient cases have shown that the success rate of the new CBR retrieval is higher than that of the original system. (paper)

  4. Multiobjective optimization with a modified simulated annealing algorithm for external beam radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Aubry, Jean-Francois; Beaulieu, Frederic; Sevigny, Caroline; Beaulieu, Luc; Tremblay, Daniel

    2006-01-01

    Inverse planning in external beam radiotherapy often requires a scalar objective function that incorporates importance factors to mimic the planner's preferences between conflicting objectives. Defining those importance factors is not straightforward, and frequently leads to an iterative process in which the importance factors become variables of the optimization problem. In order to avoid this drawback of inverse planning, optimization using algorithms more suited to multiobjective optimization, such as evolutionary algorithms, has been suggested. However, much inverse planning software, including one based on simulated annealing developed at our institution, does not include multiobjective-oriented algorithms. This work investigates the performance of a modified simulated annealing algorithm used to drive aperture-based intensity-modulated radiotherapy inverse planning software in a multiobjective optimization framework. For a few test cases involving gastric cancer patients, the use of this new algorithm leads to an increase in optimization speed of a little more than a factor of 2 over a conventional simulated annealing algorithm, while giving a close approximation of the solutions produced by a standard simulated annealing. A simple graphical user interface designed to facilitate the decision-making process that follows an optimization is also presented

  5. Adaptive Radiotherapy Planning on Decreasing Gross Tumor Volumes as Seen on Megavoltage Computed Tomography Images

    International Nuclear Information System (INIS)

    Woodford, Curtis; Yartsev, Slav; Dar, A. Rashid; Bauman, Glenn; Van Dyk, Jake

    2007-01-01

    Purpose: To evaluate gross tumor volume (GTV) changes for patients with non-small-cell lung cancer by using daily megavoltage (MV) computed tomography (CT) studies acquired before each treatment fraction on helical tomotherapy and to relate the potential benefit of adaptive image-guided radiotherapy to changes in GTV. Methods and Materials: Seventeen patients were prescribed 30 fractions of radiotherapy on helical tomotherapy for non-small-cell lung cancer at London Regional Cancer Program from Dec 2005 to March 2007. The GTV was contoured on the daily MVCT studies of each patient. Adapted plans were created using merged MVCT-kilovoltage CT image sets to investigate the advantages of replanning for patients with differing GTV regression characteristics. Results: Average GTV change observed over 30 fractions was -38%, ranging from -12 to -87%. No significant correlation was observed between GTV change and patient's physical or tumor features. Patterns of GTV changes in the 17 patients could be divided broadly into three groups with distinctive potential for benefit from adaptive planning. Conclusions: Changes in GTV are difficult to predict quantitatively based on patient or tumor characteristics. If changes occur, there are points in time during the treatment course when it may be appropriate to adapt the plan to improve sparing of normal tissues. If GTV decreases by greater than 30% at any point in the first 20 fractions of treatment, adaptive planning is appropriate to further improve the therapeutic ratio

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

    Directory of Open Access Journals (Sweden)

    Justin C Park

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

  7. Hippocampal sparing radiotherapy for glioblastoma patients: a planning study using volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Hofmaier, Jan; Kantz, Steffi; Söhn, Matthias; Dohm, Oliver S.; Bächle, Stefan; Alber, Markus; Parodi, Katia; Belka, Claus; Niyazi, Maximilian

    2016-01-01

    The purpose of this study is to investigate the potential to reduce exposure of the contralateral hippocampus in radiotherapy for glioblastoma using volumetric modulated arc therapy (VMAT). Datasets of 27 patients who had received 3D conformal radiotherapy (3D-CRT) for glioblastoma with a prescribed dose of 60Gy in fractions of 2Gy were included in this planning study. VMAT plans were optimized with the aim to reduce the dose to the contralateral hippocampus as much as possible without compromising other parameters. Hippocampal dose and treatment parameters were compared to the 3D-CRT plans using the Wilcoxon signed-rank test. The influence of tumour location and PTV size on the hippocampal dose was investigated with the Mann–Whitney-U-test and Spearman’s rank correlation coefficient. The median reduction of the contralateral hippocampus generalized equivalent uniform dose (gEUD) with VMAT was 36 % compared to the original 3D-CRT plans (p < 0.05). Other dose parameters were maintained or improved. The median V30Gy brain could be reduced by 17.9 % (p < 0.05). For VMAT, a parietal and a non-temporal tumour localisation as well as a larger PTV size were predictors for a higher hippocampal dose (p < 0.05). Using VMAT, a substantial reduction of the radiotherapy dose to the contralateral hippocampus for patients with glioblastoma is feasible without compromising other treatment parameters. For larger PTV sizes, less sparing can be achieved. Whether this approach is able to preserve the neurocognitive status without compromising the oncological outcome needs to be investigated in the setting of prospective clinical trials

  8. Evaluation of compensation in breast radiotherapy: a planning study using multiple static fields

    International Nuclear Information System (INIS)

    Donovan, Ellen M.; Johnson, Ursula; Shentall, Glyn; Evans, Philip M.; Neal, Anthony J.; Yarnold, John R.

    2000-01-01

    Purpose: A method that uses electronic portal imaging to design intensity-modulated beams for compensation in breast radiotherapy was implemented using multiple static fields in a planning study. We present the results of the study to verify the algorithm, and to assess improvements to the dosimetry. Methods and Materials: Fourteen patients were imaged with computed tomography (CT) and on a treatment unit using an electronic portal imager. The portal imaging data were used to design intensity-modulated beams to give an ideal dose distribution in the breast. These beams were implemented as multiple static fields added to standard wedged tangential fields. Planning of these treatments was performed on a commercial treatment planning system (Target 2, IGE Medical Systems, Slough, U.K.) using the CT data for each patient. Dose-volume histogram (DVH) analysis of the plans with and without multileaf collimator (MLC) compensation was carried out. This work has been used as the basis for a randomized clinical trial investigating whether improvements in dosimetry are correlated with the reduction of long-term side effects from breast radiotherapy. Results: The planning analysis showed a mean increase in target volume receiving 95-105% of prescribed dose of 7.5% (range -0.8% to 15.9%) when additional MLC compensation was applied. There was no change to the minimum dose for all 14 patient data sets. The change in the volume of breast tissue receiving over 105% of prescribed dose, when applying MLC compensation, was between -1.4% and 11.9%, with positive numbers indicating an improvement. These effects showed a correlation with breast size; the larger the breast the greater the amount of improvement. Conclusions: The method for designing compensation for breast treatments using an electronic portal imager has been verified using planning on CT data for 14 patients. An improvement was seen in planning when applying MLC compensation and this effect was greater the larger the

  9. Monte Carlo treatment planning with modulated electron radiotherapy: framework development and application

    Science.gov (United States)

    Alexander, Andrew William

    Within the field of medical physics, Monte Carlo radiation transport simulations are considered to be the most accurate method for the determination of dose distributions in patients. The McGill Monte Carlo treatment planning system (MMCTP), provides a flexible software environment to integrate Monte Carlo simulations with current and new treatment modalities. A developing treatment modality called energy and intensity modulated electron radiotherapy (MERT) is a promising modality, which has the fundamental capabilities to enhance the dosimetry of superficial targets. An objective of this work is to advance the research and development of MERT with the end goal of clinical use. To this end, we present the MMCTP system with an integrated toolkit for MERT planning and delivery of MERT fields. Delivery is achieved using an automated "few leaf electron collimator" (FLEC) and a controller. Aside from the MERT planning toolkit, the MMCTP system required numerous add-ons to perform the complex task of large-scale autonomous Monte Carlo simulations. The first was a DICOM import filter, followed by the implementation of DOSXYZnrc as a dose calculation engine and by logic methods for submitting and updating the status of Monte Carlo simulations. Within this work we validated the MMCTP system with a head and neck Monte Carlo recalculation study performed by a medical dosimetrist. The impact of MMCTP lies in the fact that it allows for systematic and platform independent large-scale Monte Carlo dose calculations for different treatment sites and treatment modalities. In addition to the MERT planning tools, various optimization algorithms were created external to MMCTP. The algorithms produced MERT treatment plans based on dose volume constraints that employ Monte Carlo pre-generated patient-specific kernels. The Monte Carlo kernels are generated from patient-specific Monte Carlo dose distributions within MMCTP. The structure of the MERT planning toolkit software and

  10. A multicriteria framework with voxel-dependent parameters for radiotherapy treatment plan optimization

    International Nuclear Information System (INIS)

    Zarepisheh, Masoud; Uribe-Sanchez, Andres F.; Li, Nan; Jia, Xun; Jiang, Steve B.

    2014-01-01

    Purpose: To establish a new mathematical framework for radiotherapy treatment optimization with voxel-dependent optimization parameters. Methods: In the treatment plan optimization problem for radiotherapy, a clinically acceptable plan is usually generated by an optimization process with weighting factors or reference doses adjusted for a set of the objective functions associated to the organs. Recent discoveries indicate that adjusting parameters associated with each voxel may lead to better plan quality. However, it is still unclear regarding the mathematical reasons behind it. Furthermore, questions about the objective function selection and parameter adjustment to assure Pareto optimality as well as the relationship between the optimal solutions obtained from the organ-based and voxel-based models remain unanswered. To answer these questions, the authors establish in this work a new mathematical framework equipped with two theorems. Results: The new framework clarifies the different consequences of adjusting organ-dependent and voxel-dependent parameters for the treatment plan optimization of radiation therapy, as well as the impact of using different objective functions on plan qualities and Pareto surfaces. The main discoveries are threefold: (1) While in the organ-based model the selection of the objective function has an impact on the quality of the optimized plans, this is no longer an issue for the voxel-based model since the Pareto surface is independent of the objective function selection and the entire Pareto surface could be generated as long as the objective function satisfies certain mathematical conditions; (2) All Pareto solutions generated by the organ-based model with different objective functions are parts of a unique Pareto surface generated by the voxel-based model with any appropriate objective function; (3) A much larger Pareto surface is explored by adjusting voxel-dependent parameters than by adjusting organ-dependent parameters, possibly

  11. Multi-institutional comparison of simulated treatment delivery errors in ssIMRT, manually planned VMAT and autoplan-VMAT plans for nasopharyngeal radiotherapy

    DEFF Research Database (Denmark)

    Pogson, Elise M; Aruguman, Sankar; Hansen, Christian R

    2017-01-01

    PURPOSE: To quantify the impact of simulated errors for nasopharynx radiotherapy across multiple institutions and planning techniques (auto-plan generated Volumetric Modulated Arc Therapy (ap-VMAT), manually planned VMAT (mp-VMAT) and manually planned step and shoot Intensity Modulated Radiation...... Therapy (mp-ssIMRT)). METHODS: Ten patients were retrospectively planned with VMAT according to three institution's protocols. Within one institution two further treatment plans were generated using differing treatment planning techniques. This resulted in mp-ssIMRT, mp-VMAT, and ap-VMAT plans. Introduced...

  12. Adaptive plan selection vs. re-optimisation in radiotherapy for bladder cancer: A dose accumulation comparison

    International Nuclear Information System (INIS)

    Vestergaard, Anne; Muren, Ludvig Paul; Søndergaard, Jimmi; Elstrøm, Ulrik Vindelev; Høyer, Morten; Petersen, Jørgen B.

    2013-01-01

    Purpose: Patients with urinary bladder cancer are obvious candidates for adaptive radiotherapy (ART) due to large inter-fractional variation in bladder volumes. In this study we have compared the normal tissue sparing potential of two ART strategies: daily plan selection (PlanSelect) and daily plan re-optimisation (ReOpt). Materials and methods: Seven patients with bladder cancer were included in the study. For the PlanSelect strategy, a patient-specific library of three plans was generated, and the most suitable plan based on the pre-treatment cone beam CT (CBCT) was selected. For the daily ReOpt strategy, plans were re-optimised based on the CBCT from each daily fraction. Bladder contours were propagated to the CBCT scan using deformable image registration (DIR). Accumulated dose distributions for the ART strategies as well as the non-adaptive RT were calculated. Results: A considerable sparing of normal tissue was achieved with both ART approaches, with ReOpt being the superior technique. Compared to non-adaptive RT, the volume receiving more than 57 Gy (corresponding to 95% of the prescribed dose) was reduced to 66% (range 48–100%) for PlanSelect and to 41% (range 33–50%) for ReOpt. Conclusion: This study demonstrated a considerable normal tissue sparing potential of ART for bladder irradiation, with clearly superior results by daily adaptive re-optimisation

  13. CT planning of boost irradiation in radiotherapy of breast cancer after conservative surgery

    International Nuclear Information System (INIS)

    Messer, Peter M.; Kirikuta, Ion C.; Bratengeier, Klaus; Flentje, Michael

    1997-01-01

    Background and purpose: A study was performed to compare the accuracy of clinical treatment set-up and CT planning of boost irradiation in radiotherapy of breast cancer. Material and methods: Between September 1993 and October 1994, 45 women who underwent breast conserving surgery and irradiation containing a boost to the tumour bed were investigated. Prospective evaluation of CT planning of the boost was carried out. The target volume/boost field, electron energy and treatment set-up had been defined on the basis of clinical examination, initial and postsurgical mammograms by one radiotherapist. Next, a planning CT was performed in treatment position and a CT-based treatment plan was calculated according to a target volume defined by another radiotherapist. The clinical treatment set-up was imported into our computer planning system and the resulting isodose plots were compared with those from CT planning and reviewed critically. Results: The clinically defined treatment set-up had to be modified in 80% of the patients. Most discrepancies observed were related to the size of the boost field itself and the chosen electron energy. Minor changes had to be made with respect to angle of table and gantry. Conclusions: Critical review of the isodose plots from both methods showed clear advantages for CT planning. Guidelines for target definition in CT planning of boost irradiation and subgroups of patients benefiting from this technique are described

  14. Dosimetric inter-institutional comparison in European radiotherapy centres: Results of IAEA supported treatment planning system audit.

    Science.gov (United States)

    Gershkevitsh, Eduard; Pesznyak, Csilla; Petrovic, Borislava; Grezdo, Joseph; Chelminski, Krzysztof; do Carmo Lopes, Maria; Izewska, Joanna; Van Dyk, Jacob

    2014-05-01

    One of the newer audit modalities operated by the International Atomic Energy Agency (IAEA) involves audits of treatment planning systems (TPS) in radiotherapy. The main focus of the audit is the dosimetry verification of the delivery of a radiation treatment plan for three-dimensional (3D) conformal radiotherapy using high energy photon beams. The audit has been carried out in eight European countries - Estonia, Hungary, Latvia, Lithuania, Serbia, Slovakia, Poland and Portugal. The corresponding results are presented. The TPS audit reviews the dosimetry, treatment planning and radiotherapy delivery processes using the 'end-to-end' approach, i.e. following the pathway similar to that of the patient, through imaging, treatment planning and dose delivery. The audit is implemented at the national level with IAEA assistance. The national counterparts conduct the TPS audit at local radiotherapy centres through on-site visits. TPS calculated doses are compared with ion chamber measurements performed in an anthropomorphic phantom for eight test cases per algorithm/beam. A set of pre-defined agreement criteria is used to analyse the performance of TPSs. TPS audit was carried out in 60 radiotherapy centres. In total, 190 data sets (combination of algorithm and beam quality) have been collected and reviewed. Dosimetry problems requiring interventions were discovered in about 10% of datasets. In addition, suboptimal beam modelling in TPSs was discovered in a number of cases. The TPS audit project using the IAEA methodology has verified the treatment planning system calculations for 3D conformal radiotherapy in a group of radiotherapy centres in Europe. It contributed to achieving better understanding of the performance of TPSs and helped to resolve issues related to imaging, dosimetry and treatment planning.

  15. Tally and geometry definition influence on the computing time in radiotherapy treatment planning with MCNP Monte Carlo code.

    Science.gov (United States)

    Juste, B; Miro, R; Gallardo, S; Santos, A; Verdu, G

    2006-01-01

    The present work has simulated the photon and electron transport in a Theratron 780 (MDS Nordion) (60)Co radiotherapy unit, using the Monte Carlo transport code, MCNP (Monte Carlo N-Particle), version 5. In order to become computationally more efficient in view of taking part in the practical field of radiotherapy treatment planning, this work is focused mainly on the analysis of dose results and on the required computing time of different tallies applied in the model to speed up calculations.

  16. Geometric moments and artificial neural network in per optimization of radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Yahaqi, E.; Movafeghi, A.; Hosseini- Ashrafi, M.E.

    2004-01-01

    Given the number of possible combinations of different setting in radiotherapy such as the number of fields etc., arriving at an optimum treatment plan with a completely conventional solution would require an unacceptable number of interaction. Using a priori information whether of a qualitative or quantitative nature has the potential of greatly reducing amount of calculation required in any optimization procedure. Having extracted the outline of the body counter line the treatment area, the sensitive organ and any in- homogeneity present in the given cross section quantitative information in the form of moments is calculated for each treatment case. An artificial neural network classifier is then developed using group of sample treatment case and applied to arrive at initial treatment plan for any new case. The approach has been shown to have strong potential for greatly reducing the number of choices in selecting the optimum answer in treatment planning

  17. CT images and radiotherapy treatment planning of patients with breast cancer: A dataset

    Directory of Open Access Journals (Sweden)

    Mohammad Rezaei

    2017-08-01

    Full Text Available The data presented here were originally collected for the research project “CT-Scan processing and analysis in patient with breast cancer after radiotherapy”. Also, it reported in our study “Prediction of Lung Tissue Damage by Evaluating Clinical and Dosimetric Parameters in Breast Cancer Patients” (Hasanabdali et al., 2016 [1]. This article describes and directly links to 52 subjects referred to Mahdieh Oncology and Radiotherapy Center from February to August 2015. Treatment planning was done for delivering 50 Gy dose to PTV in 25 fractions. the lungs and heart objects were extracted from CT images along with compliance Dose plan. Dose-volume histogram (DVH and Dose-mass histogram (DMH extracted using CT images and dose plan matrix. Moreover, the complete clinical and dosimetric specifications of subjects is attached.

  18. MRI-based treatment planning for radiotherapy: Dosimetric verification for prostate IMRT

    International Nuclear Information System (INIS)

    Chen, Lili; Price, Robert A.; Wang Lu; Li Jinsheng; Qin Lihong; McNeeley, Shawn; Ma, C.-M. Charlie; Freedman, Gary M.; Pollack, Alan

    2004-01-01

    and dose predicted by the planning system in the physical phantom. Conclusions: Magnetic resonance imaging is a useful tool for radiotherapy simulation. Compared with CT-based treatment planning, MR imaging-based treatment planning meets the accuracy for dose calculation and provides consistent treatment plans for prostate IMRT. Because MR imaging-based digitally reconstructed radiographs do not provide adequate bony structure information, a technique is suggested for producing a wire-frame image that is intended to replace the traditional digitally reconstructed radiographs that are made from CT information

  19. Commissioning and quality control of a dedicated wide bore 3T MRI simulator for radiotherapy planning

    Directory of Open Access Journals (Sweden)

    Aitang Xing

    2016-06-01

    Full Text Available Purpose: The purpose of this paper is to describe a practical approach to commissioning and quality assurance (QA of a dedicated wide-bore 3 Tesla (3T magnetic resonance imaging (MRI scanner for radiotherapy planning.Methods: A comprehensive commissioning protocol focusing on radiotherapy (RT specific requirements was developed and performed. RT specific tests included: uniformity characteristics of radio-frequency (RF coil, couch top attenuation, geometric distortion, laser and couch movement and an end-to-end radiotherapy treatment planning test. General tests for overall system performance and safety measurements were also performed.Results: The use of pre-scan based intensity correction increased the uniformity from 61.7% to 97% (body flexible coil, from 50% to 90% (large flexible coil and from 51% to 98% (small flexible coil. RT flat top couch decreased signal-to-noise ratio (SNR by an average of 42%. The mean and maximum geometric distortion was found to be 1.25 mm and 4.08 mm for three dimensional (3D corrected image acquisition, 2.07 mm and 7.88 mm for two dimensional (2D corrected image acquisition over 500 mm × 375 mm × 252 mm field of view (FOV. The accuracy of the laser and couch movement was less than ±1 mm. The standard deviation of registration parameters for the end-to-end test was less than 0.41 mm. An on-going QA program was developed to monitor the system’s performance.Conclusion: A number of RT specific tests have been described for commissioning and subsequent performance monitoring of a dedicated MRI simulator (MRI-Sim. These tests have been important in establishing and maintaining its operation for RT planning.

  20. Integration of molecular imaging in treatment planning and delivery of modern radiotherapy

    International Nuclear Information System (INIS)

    Jacob, V.; Wilkens, J.J.

    2011-01-01

    Among various imaging modalities currently available, positron emission tomography (PET) has the potential to visualize processes on a molecular level. Molecular imaging, often also referred to as functional or biological imaging, brought a new dimension to diagnostics and therapy of cancer by providing images of metabolism and other processes in the human body and in tumours. PET was first applied for diagnostics and staging of various tumours with high diagnostic precision. Modern radiotherapy asks increasingly for individualized treatment strategies, taking molecular imaging into account. Technical developments over the last years, in particular methods to register various imaging modalities within software packages for treatment planning and target delineation, facilitated the use of PET imaging in radiotherapy. In order to exploit the full potential of modern high-precision radiotherapy, exact imaging procedures are necessary, for example for precise target volume definition. In the long run, concepts employing an inhomogeneous dose prescription based on biological imaging may become routine in clinical applications, leading to individualized, biologically adaptive therapy. (orig.)

  1. CT and MRI matching for radiotherapy planning in head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Rasch, C; Keus, R; Touw, A; Lebesque, J; Van Herk, M [Nederlands Kanker Inst. ` Antoni van Leeuwenhoekhuis` , Amsterdam (Netherlands)

    1995-12-01

    The objective of this study was to evaluate the impact of matched CT and MRI information on target delineation in radiotherapy planning for head and neck tumors. MRI images of eight patients with head and neck cancer in supine position, not necessarily obtained in radiotherapy treatment position were matched to the CT scans made in radiotherapy position using automatic three-dimensional chamfer-matching of bony structures. Four independent observers delineated the Gross Tumor Volume (GTV) in CT scans and axial and sagittal MR scans. The GTV`s were compared, overlapping volumes and non-overlapping volumes between the different datasets and observers were determined. In all patients a good match of CT and MRI information was accomplished in the head region. The combined information provided a better visualisation of the GTV, oedema and normal tissues compared with CT or MRI alone. Determination of overlapping and non-overlapping volumes proved to be a valuable tool to measure uncertainties in the determination of the GTV. CT-MRI matching in patients with head and neck tumors is feasible and makes a more accurate irradiation with higher tumor doses and less normal tissue complications possible. Remaining uncertainties in the determination of the GTV can be quantified using the combined information of MRI and CT.

  2. Optimization of stereotactic body radiotherapy treatment planning using a multicriteria optimization algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Ghandour, Sarah; Cosinschi, Adrien; Mazouni, Zohra; Pachoud, Marc; Matzinger, Oscar [Riviera-Chablais Hospital, Vevey (Switzerland). Cancer Center, Radiotherapy Dept.

    2016-07-01

    To provide high-quality and efficient dosimetric planning for various types of stereotactic body radiotherapy (SBRT) for tumor treatment using a multicriteria optimization (MCO) technique fine-tuned with direct machine parameter optimization (DMPO). Eighteen patients with lung (n = 11), liver (n = 5) or adrenal cell cancer (n = 2) were treated using SBRT in our clinic between December 2014 and June 2015. Plans were generated using the RayStation trademark Treatment Planning System (TPS) with the VMAT technique. Optimal deliverable SBRT plans were first generated using an MCO algorithm to find a well-balanced tradeoff between tumor control and normal tissue sparing in an efficient treatment planning time. Then, the deliverable plan was post-processed using the MCO solution as the starting point for the DMPO algorithm to improve the dose gradient around the planning target volume (PTV) while maintaining the clinician's priorities. The dosimetric quality of the plans was evaluated using dose-volume histogram (DVH) parameters, which account for target coverage and the sparing of healthy tissue, as well as the CI100 and CI50 conformity indexes. Using a combination of the MCO and DMPO algorithms showed that the treatment plans were clinically optimal and conformed to all organ risk dose volume constraints reported in the literature, with a computation time of approximately one hour. The coverage of the PTV (D99% and D95%) and sparing of organs at risk (OAR) were similar between the MCO and MCO + DMPO plans, with no significant differences (p > 0.05) for all the SBRT plans. The average CI100 and CI50 values using MCO + DMPO were significantly better than those with MCO alone (p < 0.05). The MCO technique allows for convergence on an optimal solution for SBRT within an efficient planning time. The combination of the MCO and DMPO techniques yields a better dose gradient, especially for lung tumors.

  3. Definition of postlumpectomy tumor bed for radiotherapy boost field planning: CT versus surgical clips

    International Nuclear Information System (INIS)

    Goldberg, Hadassah; Prosnitz, Robert G.; Olson, John A.; Marks, Lawrence B.

    2005-01-01

    Purpose: To compare the location and extent of the tumor bed as defined by surgical clips and computed tomography (CT) scans, after lumpectomy, for electron boost planning as part of breast radiotherapy. Methods and Materials: Planning CT images of 31 operated breasts in 30 patients who underwent lumpectomy were reviewed. One or more clips were placed in the lumpectomy cavity. Serial CT images were used to measure the depth and transverse and longitudinal dimensions. The area and geometric center of the tumor bed were defined by the clips and CT. Results: The CT and clip measurements were identical for the maximal tumor depth in 27 of 30 patients. The CT bed extended beyond the clips by 0-7 mm medially in the transverse/longitudinal extent (multiclip patients). The median distance between the geometric centers in the coronal plane for the tumor bed center was larger for patients with single clips than for those with multiple clips (p 2 . The CT bed was more readily visible in patients with a shorter interval between surgery and radiotherapy. Conclusion: The maximal depth of the tumor bed was similar using the two methods. The extent and centers of the clip-and CT-determined beds differed significantly. This may indicate an underestimation of the tumor bed as defined by clips only and justifies integration of CT information in boost field planning

  4. Treatment Planning for Pulsed Reduced Dose-Rate Radiotherapy in Helical Tomotherapy

    International Nuclear Information System (INIS)

    Rong Yi; Paliwal, Bhudatt; Howard, Steven P.; Welsh, James

    2011-01-01

    Purpose: Pulsed reduced dose-rate radiotherapy (PRDR) is a valuable method of reirradiation because of its potential to reduce late normal tissue toxicity while still yielding significant tumoricidal effect. A typical method using a conventional linear accelerator (linac) is to deliver a series of 20-cGy pulses separated by 3-min intervals to give an effective dose-rate of just under 7 cGy/min. Such a strategy is fraught with difficulties when attempted on a helical tomotherapy unit. We investigated various means to overcome this limitation. Methods and Materials: Phantom and patient cases were studied. Plans were generated with varying combinations of field width (FW), pitch, and modulation factor (MF) to administer 200 cGy per fraction to the planning target in eight subfractions, thereby mimicking the technique used on conventional linacs. Plans were compared using dose-volume histograms, homogeneity indices, conformation numbers, and treatment time. Plan delivery quality assurance was performed to assess deliverability. Results: It was observed that for helical tomotherapy, intrinsic limitations in leaf open time in the multileaf collimator deteriorate plan quality and deliverability substantially when attempting to deliver very low doses such as 20-40 cGy. The various permutations evaluated revealed that the combination of small FW (1.0 cm), small MF (1.3-1.5), and large pitch (∼0.86), along with the half-gantry-angle-blocked scheme, can generate clinically acceptable plans with acceptable delivery accuracy (±3%). Conclusion: Pulsed reduced dose-rate radiotherapy can be accurately delivered using helical tomotherapy for tumor reirradiation when the appropriate combination of FW, MF, and pitch is used.

  5. PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning

    DEFF Research Database (Denmark)

    Sattler, Bernhard; Lee, John A; Lonsdale, Markus

    2010-01-01

    -invasive imaging technique, offers the visualization and quantification of pre-selected tracer metabolism. In combination with the structural information from CT, this molecular imaging technique has great potential to support and improve the outcome of the treatment-planning procedure prior to radiotherapy......, the DICOM-Standard provides objects and classes for this purpose (DICOM RT). Furthermore, the standard DICOM objects and classes for nuclear medicine (NM, PT) and computed tomography (CT) are used to communicate the actual image data created by the modalities. Care must be taken for data security...

  6. Evaluation of multi-modality CT-MRI-SPECT registration tools for radiotherapy treatment planning purposes

    International Nuclear Information System (INIS)

    Bianchini, S.; Alfonso, R.; Castillo, J.; Coca, M.; Torres, L.

    2013-01-01

    A qualitative and quantitative comparison of registration CT-CT, CT-MR and CT-SPECT performed by the different software and algorithms studies is presented. Only two studied software were full DICOM RT compatible while accepting DICOM images in any layout. Quantitative results of fiducial displacement errors were calculated for all software and available registration methods. The presented methodology demonstrated being effective for assessing the quality of studied image registration tools in the radiotherapy planning context, provided the images are free of significant geometric deformation. When implementing this methodology in real patients, the use of immobilization devices, such as thermoplastic masks, is recommended for enhanced quality of image registration. (Author)

  7. Use of digitally reconstructed radiographs in radiotherapy treatment planning and verification

    International Nuclear Information System (INIS)

    Yang, C.; Guiney, M.; Hughes, P.; Leung, S.; Liew, K.H.; Matar, J.; Quong, G.

    2000-01-01

    The authors present 3 years of experience of using digitally reconstructed radiographs (DRR) for radiotherapy planning and verification. Comparison is made with simulation film (SF) to illustrate the advantages of DRR over SF. Emphasis is placed on using the appropriate equipment and applying the correct technique. A brief discourse on the principle of CT imaging is presented to illustrate the operation of CT software and optimization of image display for axial slices and DRR. Emphasis placed on the application of clinical knowledge to enhance the usefulness as well as the technical quality of the DRR. Illustrative examples are given. Copyright (1999) Blackwell Science Pty Ltd

  8. Investigations on the quality of manual image segmentation in 3D radiotherapy planning

    International Nuclear Information System (INIS)

    Perelmouter, J.; Tuebingen Univ.; Bohsung, J.; Nuesslin, F.; Becker, G.; Kortmann, R.D.; Bamberg, M.

    1998-01-01

    In 3D radiotherapy planning image segmentation plays an important role in the definition process of target volume and organs at risk. Here, we present a method to quantify the technical precision of the manual image segmentation process. To validate our method we developed a virtual phantom consisting of several geometrical objects of changing form and contrast, which should be contoured by volunteers using the TOMAS tool for manual segmentation of the Heidelberg VOXELPLAN system. The results of this examination are presented. (orig.) [de

  9. Physical-dosimetric enabling a dual linear accelerator 3D planning systems for radiotherapy

    International Nuclear Information System (INIS)

    Alfonso, Rodolfo; Martinez, William; Arelis, Lores; Morales, Jorge

    2009-01-01

    The process of commissioning clinical linear accelerator requires a dual comprehensive study of the therapeutic beam parameters, both photons Electron. All information gained by measuring physical and dosimetric these beams must be analyzed, processed and refined for further modeling in computer-based treatment planning (RTPS). Of professionalism of this process will depend on the accuracy and precision of the calculations the prescribed doses. This paper aims to demonstrate availability clinical linear accelerator system-RTPS with late radiotherapy treatments shaped beam of photons and electrons. (author)

  10. Design of security scheme of the radiotherapy planning administration system based on the hospital information system

    International Nuclear Information System (INIS)

    Zhuang Yongzhi; Zhao Jinzao

    2010-01-01

    Objective: To design a security scheme of radiotherapy planning administration system. Methods: Power Builder 9i language was used to program the system through the model of client-server machine. Oracle 9i was used as the database server. Results In this system, user registration management, user login management, application-level functions of control, database access control, and audit trail were designed to provide system security. Conclusions: As a prototype for the security analysis and protection of this scheme provides security of the system, application system, important data and message, which ensures the system work normally. (authors)

  11. Potential impact of 68Ga-DOTATOC PET/CT on stereotactic radiotherapy planning of meningiomas

    International Nuclear Information System (INIS)

    Nyuyki, Fonyuy; Plotkin, Michail; Michel, Roger; Steffen, Ingo; Fahdt, Daniel; Brenner, Winfried; Graf, Reinhold; Denecke, Timm; Geworski, Lilli; Wurm, Reinhard

    2010-01-01

    Since meningiomas show a high expression of somatostatin receptor subtype 2, PET with 68 Ga-DOTATOC was proposed as an additional imaging modality beside CT and MRI for planning radiotherapy. We investigated the input of 68 Ga-DOTATOC-PET/CT on the definition of the ''gross tumour volume'' (GTV) in meningiomas, in order to assess the potential value of this method. Prior to radiotherapy, 42 patients with meningiomas (26 f, 16 m, mean age 55) underwent MRI and 68 Ga-DOTATOC-PET/CT examinations. History: operated n = 24, radiotherapy n = 1, operation and radiotherapy n = 8, no treatment n = 9. PET/CT and MRI data were co-registered using a BrainLAB workstation. For comparison, the GTV was defined first under consideration of CT and MRI data, then using PET data. 3/42 patients were excluded from the analysis (two with negative PET results, one with an extensive tumour, not precisely delineable by MRI or PET/CT). The average GTV CT/MRI was 22(±19)cm 3 ; GTV PET was 23(±20)cm 3 . Additional GTV, obtained as a result of PET was 9(±10)cm 3 and was observed in patients with osseous infiltration. In some pre-treated patients there were intratumoural areas (as identified in CT/MRI) without SR-expression (7(±11)cm 3 ). Common GTV as obtained by both CT/MRI and PET was 15(±14)cm 3 . The mean bi-directional difference between the GTV CT/MRI and GTV PET accounted to 16(±15)cm 3 (93%, p 68 Ga-DOTATOC-PET enables delineation of SR-positive meningiomas and delivers additional information to both CT and MRI regarding the planning of stereotactic radiotherapy. The acquisition on a PET/CT scanner helps to estimate the relation of PET findings to anatomical structures and is especially useful for detection of osseous infiltration. 68 Ga-DOTATOC-PET also allows detection of additional lesions in patients with multiple meningiomas. (orig.)

  12. Poster - 36: Effect of Planning Target Volume Coverage on the Dose Delivered in Lung Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Dekker, Chris; Wierzbicki, Marcin [McMaster University, Juravinski Cancer Centre (Canada)

    2016-08-15

    Purpose: In lung radiotherapy, breathing motion may be encompassed by contouring the internal target volume (ITV). Remaining uncertainties are included in a geometrical expansion to the planning target volume (PTV). In IMRT, the treatment is then optimized until a desired PTV fraction is covered by the appropriate dose. The resulting beams often carry high fluence in the PTV margin to overcome low lung density and to generate steep dose gradients. During treatment, the high density tumour can enter the PTV margin, potentially increasing target dose. Thus, planning lung IMRT with a reduced PTV dose may still achieve the desired ITV dose during treatment. Methods: A retrospective analysis was carried out with 25 IMRT plans prescribed to 63 Gy in 30 fractions. The plans were re-normalized to cover various fractions of the PTV by different isodose lines. For each case, the isocentre was moved using 125 shifts derived from all 3D combinations of 0 mm, (PTV margin - 1 mm), and PTV margin. After each shift, the dose was recomputed to approximate the delivered dose. Results and Conclusion: Our plans typically cover 95% of the PTV by 95% of the dose. Reducing the PTV covered to 94% did not significantly reduce the delivered ITV doses for (PTV margin - 1 mm) shifts. Target doses were reduced significantly for all other shifts and planning goals studied. Thus, a reduced planning goal will likely deliver the desired target dose as long as the ITV rarely enters the last mm of the PTV margin.

  13. Comparing conformal, arc radiotherapy and helical tomotherapy in craniospinal irradiation planning.

    Science.gov (United States)

    Myers, Pamela A; Mavroidis, Panayiotis; Papanikolaou, Nikos; Stathakis, Sotirios

    2014-09-08

    Currently, radiotherapy treatment plan acceptance is based primarily on dosimetric performance measures. However, use of radiobiological analysis to assess benefit in terms of tumor control and harm in terms of injury to normal tissues can be advantageous. For pediatric craniospinal axis irradiation (CSI) patients, in particular, knowing the technique that will optimize the probabilities of benefit versus injury can lead to better long-term outcomes. Twenty-four CSI pediatric patients (median age 10) were retrospectively planned with three techniques: three-dimensional conformal radiation therapy (3D CRT), volumetric-modulated arc therapy (VMAT), and helical tomotherapy (HT). VMAT plans consisted of one superior and one inferior full arc, and tomotherapy plans were created using a 5.02cm field width and helical pitch of 0.287. Each plan was normalized to 95% of target volume (whole brain and spinal cord) receiving prescription dose 23.4Gy in 13 fractions. Using an in-house MATLAB code and DVH data from each plan, the three techniques were evaluated based on biologically effective uniform dose (D=), the complication-free tumor control probability (P+), and the width of the therapeutically beneficial range. Overall, 3D CRT and VMAT plans had similar values of D= (24.1 and 24.2 Gy), while HT had a D= slightly lower (23.6 Gy). The average values of the P+ index were 64.6, 67.4, and 56.6% for 3D CRT, VMAT, and HT plans, respectively, with the VMAT plans having a statistically significant increase in P+. Optimal values of D= were 28.4, 33.0, and 31.9 Gy for 3D CRT, VMAT, and HT plans, respectively. Although P+ values that correspond to the initial dose prescription were lower for HT, after optimizing the D= prescription level, the optimal P+ became 94.1, 99.5, and 99.6% for 3D CRT, VMAT, and HT, respectively, with the VMAT and HT plans having statistically significant increases in P+. If the optimal dose level is prescribed using a radiobiological evaluation method, as

  14. Renormalization of period doubling in symmetric four-dimensional volume-preserving maps

    International Nuclear Information System (INIS)

    Mao, J.; Greene, J.M.

    1987-01-01

    We have determined three maps (truncated at quadratic terms) that are fixed under the renormalization operator of pitchfork period doubling in symmetric four-dimensional volume-preserving maps. Each of these contains the previously known two-dimensional area-preserving map that is fixed under the period-doubling operator. One of these three fixed maps consists of two uncoupled two-dimensional (nonlinear) area-preserving fixed maps. The other two contain also the two-dimensional area-preserving fixed map coupled (in general) with a linear two-dimensional map. The renormalization calculation recovers all numerical results for the pitchfork period doubling in the symmetric four-dimensional volume-preserving maps, reported by Mao and Helleman [Phys. Rev. A 35, 1847 (1987)]. For a large class of nonsymmetric four-dimensional volume-preserving maps, we found that the fixed maps are the same as those for the symmetric maps

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  16. A self-adaptive case-based reasoning system for dose planning in prostate cancer radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Nishikant; Petrovic, Sanja; Sundar, Santhanam [Automated Scheduling, Optimisation and Planning Research Group, School of Computer Science, University of Nottingham, Nottingham NG8 1BB (United Kingdom); Department of Oncology, Nottingham University Hospitals NHS Trust, Nottingham NG5 1PB (United Kingdom)

    2011-12-15

    Purpose: Prostate cancer is the most common cancer in the male population. Radiotherapy is often used in the treatment for prostate cancer. In radiotherapy treatment, the oncologist makes a trade-off between the risk and benefit of the radiation, i.e., the task is to deliver a high dose to the prostate cancer cells and minimize side effects of the treatment. The aim of our research is to develop a software system that will assist the oncologist in planning new treatments. Methods: A nonlinear case-based reasoning system is developed to capture the expertise and experience of oncologists in treating previous patients. Importance (weights) of different clinical parameters in the dose planning is determined by the oncologist based on their past experience, and is highly subjective. The weights are usually fixed in the system. In this research, the weights are updated automatically each time after generating a treatment plan for a new patient using a group based simulated annealing approach. Results: The developed approach is analyzed on the real data set collected from the Nottingham University Hospitals NHS Trust, City Hospital Campus, UK. Extensive experiments show that the dose plan suggested by the proposed method is coherent with the dose plan prescribed by an experienced oncologist or even better. Conclusions: The developed case-based reasoning system enables the use of knowledge and experience gained by the oncologist in treating new patients. This system may play a vital role to assist the oncologist in making a better decision in less computational time; it utilizes the success rate of the previously treated patients and it can also be used in teaching and training processes.

  17. Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit.

    Science.gov (United States)

    Rutonjski, Laza; Petrović, Borislava; Baucal, Milutin; Teodorović, Milan; Cudić, Ozren; Gershkevitsh, Eduard; Izewska, Joanna

    2012-09-12

    Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT) and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs). The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable.

  18. Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit

    International Nuclear Information System (INIS)

    Rutonjski, Laza; Petrović, Borislava; Baucal, Milutin; Teodorović, Milan; Čudić, Ozren; Gershkevitsh, Eduard; Izewska, Joanna

    2012-01-01

    Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT) and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs). The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable

  19. Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit

    Directory of Open Access Journals (Sweden)

    Rutonjski Laza

    2012-09-01

    Full Text Available Abstract Background Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. Methods The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs. The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. Results The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. Conclusions The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable.

  20. A self-adaptive case-based reasoning system for dose planning in prostate cancer radiotherapy

    International Nuclear Information System (INIS)

    Mishra, Nishikant; Petrovic, Sanja; Sundar, Santhanam

    2011-01-01

    Purpose: Prostate cancer is the most common cancer in the male population. Radiotherapy is often used in the treatment for prostate cancer. In radiotherapy treatment, the oncologist makes a trade-off between the risk and benefit of the radiation, i.e., the task is to deliver a high dose to the prostate cancer cells and minimize side effects of the treatment. The aim of our research is to develop a software system that will assist the oncologist in planning new treatments. Methods: A nonlinear case-based reasoning system is developed to capture the expertise and experience of oncologists in treating previous patients. Importance (weights) of different clinical parameters in the dose planning is determined by the oncologist based on their past experience, and is highly subjective. The weights are usually fixed in the system. In this research, the weights are updated automatically each time after generating a treatment plan for a new patient using a group based simulated annealing approach. Results: The developed approach is analyzed on the real data set collected from the Nottingham University Hospitals NHS Trust, City Hospital Campus, UK. Extensive experiments show that the dose plan suggested by the proposed method is coherent with the dose plan prescribed by an experienced oncologist or even better. Conclusions: The developed case-based reasoning system enables the use of knowledge and experience gained by the oncologist in treating new patients. This system may play a vital role to assist the oncologist in making a better decision in less computational time; it utilizes the success rate of the previously treated patients and it can also be used in teaching and training processes.

  1. Functional image-based radiotherapy planning for non-small cell lung cancer: A simulation study

    International Nuclear Information System (INIS)

    Bates, Emma L.; Bragg, Christopher M.; Wild, Jim M.; Hatton, Matthew Q.F.; Ireland, Rob H.

    2009-01-01

    Background and purpose: To investigate the incorporation of data from single-photon emission computed tomography (SPECT) or hyperpolarized helium-3 magnetic resonance imaging ( 3 He-MRI) into intensity-modulated radiotherapy (IMRT) planning for non-small cell lung cancer (NSCLC). Material and methods: Seven scenarios were simulated that represent cases of NSCLC with significant functional lung defects. Two independent IMRT plans were produced for each scenario; one to minimise total lung volume receiving ≥20 Gy (V 20 ), and the other to minimise only the functional lung volume receiving ≥20 Gy (FV 20 ). Dose-volume characteristics and a plan quality index related to planning target volume coverage by the 95% isodose (V PTV95 /FV 20 ) were compared between anatomical and functional plans using the Wilcoxon signed ranks test. Results: Compared to anatomical IMRT plans, functional planning reduced FV 20 (median 2.7%, range 0.6-3.5%, p = 0.02), and total lung V 20 (median 1.5%, 0.5-2.7%, p = 0.02), with a small reduction in mean functional lung dose (median 0.4 Gy, 0-0.7 Gy, p = 0.03). There were no significant differences in target volume coverage or organ-at-risk doses. Plan quality index was improved for functional plans (median increase 1.4, range 0-11.8, p = 0.02). Conclusions: Statistically significant reductions in FV 20 , V 20 and mean functional lung dose are possible when IMRT planning is supplemented by functional information derived from SPECT or 3 He-MRI.

  2. Quality Assurance Challenges for Motion-Adaptive Radiation Therapy: Gating, Breath Holding, and Four-Dimensional Computed Tomography

    International Nuclear Information System (INIS)

    Jiang, Steve B.; Wolfgang, John; Mageras, Gig S.

    2008-01-01

    Compared with conventional three-dimensional (3D) conformal radiation therapy and intensity-modulated radiation therapy treatments, quality assurance (QA) for motion-adaptive radiation therapy involves various challenges because of the added temporal dimension. Here we discuss those challenges for three specific techniques related to motion-adaptive therapy: namely respiratory gating, breath holding, and four-dimensional computed tomography. Similar to the introduction of any other new technologies in clinical practice, typical QA measures should be taken for these techniques also, including initial testing of equipment and clinical procedures, as well as frequent QA examinations during the early stage of implementation. Here, rather than covering every QA aspect in depth, we focus on some major QA challenges. The biggest QA challenge for gating and breath holding is how to ensure treatment accuracy when internal target position is predicted using external surrogates. Recommended QA measures for each component of treatment, including simulation, planning, patient positioning, and treatment delivery and verification, are discussed. For four-dimensional computed tomography, some major QA challenges have also been discussed

  3. Planned neck dissection after weekly docetaxel and concurrent radiotherapy for advanced oropharyngeal cancer

    International Nuclear Information System (INIS)

    Tomita, Toshiki; Ozawa, Hiroyuki; Sakamoto, Koji; Fujii, Ryoichi; Ogawa, Kaoru; Fujii, Masato; Yamashita, Taku; Shinden, Seiichi

    2007-01-01

    Small oropharyngeal carcinomas with advanced neck metastases (stage N2 or greater) are common. Patients with small T with large N oropharyngeal carcinoma have high rates of local control but lower rates of regional control when treated with chemoradiotherapy. Clinical assessment after chemoradiotherapy cannot ensure the absence of neck disease. In the last 5 years, we have treated patients with T1-2 with N2-3 oropharyngeal carcinoma with weekly docetaxel radiotherapy followed by planned neck dissection (PND). Our objectives were to clarify the pathologically complete response (CR) rate of neck metastasis after weekly docetaxel radiotherapy, to identify the clinical predictor of residual neck disease, and to determine the mobidity of planned neck dissection. After chemoradiotherapy, all 12 patients had a complete response at the primary site. We conducted 15 neck dissections. Of these, 6 (40%) had positive nodes. The pathological CR rate of neck metastasis was 58.3%, whereas overall 2-year neck control rate was 91.7%. These findings lend support to the role of PND after chemoradiotherapy in N2-3 neck disease. After chemoradiotherapy, clinical parameters including TN status, feasibility of chemoradiotherapy, largest lymph node size or size reduction in MRI, did not identify patients with residual neck disease. We conducted selective neck dissection (SND) in 80% of patients. SND as PND appears to be appropriate in this group of patients because of the low incidence of complications. A further cohort study including the comparison of PND nonenforcement group is necessary to clarify the validity of the addition of PND in weekly docetaxel radiotherapy. (author)

  4. Effect of contrast agent administration on consequences of dosimetry and biology in radiotherapy planning

    International Nuclear Information System (INIS)

    Lo, Ching-Jung; Yang, Pei-Ying; Chao, Tsi-Chian; Tu, Shu-Ju

    2015-01-01

    In the treatment planning of radiation therapy, patients may be administrated with contrast media in CT scanning to assist physicians for accurate delineation of the target or organs. However, contrast media are not used in patients during the treatment delivery. In particular, contrast media contain materials with high atomic numbers and dosimetric variations may occur between scenarios where contrast media are present in treatment planning and absent in treatment delivery. In this study we evaluate the effect of contrast media on the dosimetry and biological consequence. An analytical phantom based on AAPM TG 119 and five sets of CT images from clinical patients are included. Different techniques of treatment planning are considered, including 1-field AP, 2-field AP+PA, 4-field box, 7-field IMRT, and RapidArc. RapidArc is a recent technique of volumetric modulated arc therapy and is used in our study of contrast media in clinical scenarios. The effect of RapidArc on dosimetry and biological consequence for administration of contrast media in radiotherapy is not discussed previously in literature. It is shown that dose difference is reduced as the number of external beams is increased, suggesting RapidArc may be favored to be used in the treatment planning enhanced by contrast media. Linear trend lines are fitted for assessment of percent dose differences in the planning target volume versus concentrations of contrast media between plans where contrast media are present and absent, respectively

  5. Evaluation of delivered dose for a clinical daily adaptive plan selection strategy for bladder cancer radiotherapy

    International Nuclear Information System (INIS)

    Lutkenhaus, Lotte J.; Visser, Jorrit; Jong, Rianne de; Hulshof, Maarten C.C.M.; Bel, Arjan

    2015-01-01

    Purpose: To account for variable bladder size during bladder cancer radiotherapy, a daily plan selection strategy was implemented. The aim of this study was to calculate the actually delivered dose using an adaptive strategy, compared to a non-adaptive approach. Material and methods: Ten patients were treated to the bladder and lymph nodes with an adaptive full bladder strategy. Interpolated delineations of bladder and tumor on a full and empty bladder CT scan resulted in five PTVs for which VMAT plans were created. Daily cone beam CT (CBCT) scans were used for plan selection. Bowel, rectum and target volumes were delineated on these CBCTs, and delivered dose for these was calculated using both the adaptive plan, and a non-adaptive plan. Results: Target coverage for lymph nodes improved using an adaptive strategy. The full bladder strategy spared the healthy part of the bladder from a high dose. Average bowel cavity V30Gy and V40Gy significantly reduced with 60 and 69 ml, respectively (p < 0.01). Other parameters for bowel and rectum remained unchanged. Conclusions: Daily plan selection compared to a non-adaptive strategy yielded similar bladder coverage and improved coverage for lymph nodes, with a significant reduction in bowel cavity V30Gy and V40Gy only, while other sparing was limited

  6. Effect of Radiotherapy Planning Complexity on Survival of Elderly Patients With Unresected Localized Lung Cancer

    International Nuclear Information System (INIS)

    Park, Chang H.; Bonomi, Marcelo; Cesaretti, Jamie; Neugut, Alfred I.; Wisnivesky, Juan P.

    2011-01-01

    Purpose: To evaluate whether complex radiotherapy (RT) planning was associated with improved outcomes in a cohort of elderly patients with unresected Stage I-II non-small-cell lung cancer (NSCLC). Methods and Materials: Using the Surveillance, Epidemiology, and End Results registry linked to Medicare claims, we identified 1998 patients aged >65 years with histologically confirmed, unresected stage I-II NSCLC. Patients were classified into an intermediate or complex RT planning group using Medicare physician codes. To address potential selection bias, we used propensity score modeling. Survival of patients who received intermediate and complex simulation was compared using Cox regression models adjusting for propensity scores and in a stratified and matched analysis according to propensity scores. Results: Overall, 25% of patients received complex RT planning. Complex RT planning was associated with better overall (hazard ratio 0.84; 95% confidence interval, 0.75-0.95) and lung cancer-specific (hazard ratio 0.81; 95% confidence interval, 0.71-0.93) survival after controlling for propensity scores. Similarly, stratified and matched analyses showed better overall and lung cancer-specific survival of patients treated with complex RT planning. Conclusions: The use of complex RT planning is associated with improved survival among elderly patients with unresected Stage I-II NSCLC. These findings should be validated in prospective randomized controlled trials.

  7. Can field-in-field technique replace wedge filter in radiotherapy treatment planning: a comparative analysis in various treatment sites

    International Nuclear Information System (INIS)

    Prabhakar, R.; Julka, P.K.; Rath, G.K.

    2008-01-01

    The aim of the study was to show whether field-in-field (FIF) technique can be used to replace wedge filter in radiation treatment planning. The study was performed in cases where wedges are commonly used in radiotherapy treatment planning. Thirty patients with different malignancies who received radiotherapy were studied. This includes patients with malignancies of brain, head and neck, breast, upper and lower abdomen. All the patients underwent computed tomography scanning and the datasets were transferred to the treatment planning system. Initially, wedge based planning was performed to achieve the best possible dose distribution inside the target volume with multileaf collimators (Plan1). Wedges were removed from a copy of the same plan and FIF plan was generated (Plan2). The two plans were then evaluated and compared for mean dose, maximum dose, median dose, doses to 2% (D 2 ) and 98% (D 9 8) of the target volume, volume receiving greater than 107% of the prescribed dose (V>107%), volume receiving less than 95% of the prescribed dose (V 2 , V>107% and CI for more of the sites with statistically significant reduction in monitor units. FIF results in better dose distribution in terms of homogeneity in most of the sites. It is feasible to replace wedge filter with FIF in radiotherapy treatment planning.

  8. MRI-based treatment plan simulation and adaptation for ion radiotherapy using a classification-based approach

    International Nuclear Information System (INIS)

    Rank, Christopher M; Tremmel, Christoph; Hünemohr, Nora; Nagel, Armin M; Jäkel, Oliver; Greilich, Steffen

    2013-01-01

    In order to benefit from the highly conformal irradiation of tumors in ion radiotherapy, sophisticated treatment planning and simulation are required. The purpose of this study was to investigate the potential of MRI for ion radiotherapy treatment plan simulation and adaptation using a classification-based approach. Firstly, a voxelwise tissue classification was applied to derive pseudo CT numbers from MR images using up to 8 contrasts. Appropriate MR sequences and parameters were evaluated in cross-validation studies of three phantoms. Secondly, ion radiotherapy treatment plans were optimized using both MRI-based pseudo CT and reference CT and recalculated on reference CT. Finally, a target shift was simulated and a treatment plan adapted to the shift was optimized on a pseudo CT and compared to reference CT optimizations without plan adaptation. The derivation of pseudo CT values led to mean absolute errors in the range of 81 - 95 HU. Most significant deviations appeared at borders between air and different tissue classes and originated from partial volume effects. Simulations of ion radiotherapy treatment plans using pseudo CT for optimization revealed only small underdosages in distal regions of a target volume with deviations of the mean dose of PTV between 1.4 - 3.1% compared to reference CT optimizations. A plan adapted to the target volume shift and optimized on the pseudo CT exhibited a comparable target dose coverage as a non-adapted plan optimized on a reference CT. We were able to show that a MRI-based derivation of pseudo CT values using a purely statistical classification approach is feasible although no physical relationship exists. Large errors appeared at compact bone classes and came from an imperfect distinction of bones and other tissue types in MRI. In simulations of treatment plans, it was demonstrated that these deviations are comparable to uncertainties of a target volume shift of 2 mm in two directions indicating that especially

  9. Semi-automated segmentation of a glioblastoma multiforme on brain MR images for radiotherapy planning.

    Science.gov (United States)

    Hori, Daisuke; Katsuragawa, Shigehiko; Murakami, Ryuuji; Hirai, Toshinori

    2010-04-20

    We propose a computerized method for semi-automated segmentation of the gross tumor volume (GTV) of a glioblastoma multiforme (GBM) on brain MR images for radiotherapy planning (RTP). Three-dimensional (3D) MR images of 28 cases with a GBM were used in this study. First, a sphere volume of interest (VOI) including the GBM was selected by clicking a part of the GBM region in the 3D image. Then, the sphere VOI was transformed to a two-dimensional (2D) image by use of a spiral-scanning technique. We employed active contour models (ACM) to delineate an optimal outline of the GBM in the transformed 2D image. After inverse transform of the optimal outline to the 3D space, a morphological filter was applied to smooth the shape of the 3D segmented region. For evaluation of our computerized method, we compared the computer output with manually segmented regions, which were obtained by a therapeutic radiologist using a manual tracking method. In evaluating our segmentation method, we employed the Jaccard similarity coefficient (JSC) and the true segmentation coefficient (TSC) in volumes between the computer output and the manually segmented region. The mean and standard deviation of JSC and TSC were 74.2+/-9.8% and 84.1+/-7.1%, respectively. Our segmentation method provided a relatively accurate outline for GBM and would be useful for radiotherapy planning.

  10. Artificial neural network analysis applied to simplifying bioeffect radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Purnomo, A.B.

    2001-01-01

    Full text: A bioeffect planning system has been developed by Wigg and Nicholls in the Departments of Clinical Radiobiology and Medical Physics, at the Royal Adelaide Hospital. The system has been developed to be an experimental tool by means of which bioeffect plans may be compared with conventional isodose plans in radiotherapy. Limitations of isodose planning, in many common clinical circumstances, have been apparent for sometime (Wigg and Wilson, Australasian Radiology, 1981, 25: 205-212). There are many reasons why bioeffect planning has been slow in developing. These include concerns about the clinical application of theoretical radiobiology models, the uncertainty of normal tissue and tumour parameter values, and the non-availability of suitable computer systems capable of performing bioeffect planning. These concerns are fully justified and isodose planning must remain, for the foreseeable future, the gold standard for clinical treatment. However, these concerns must be judged against the certainty that isodose planning, in which the only variable usually considered is the total dose, can be substantially misleading. Unfortunately, a typical Tumour Control Probability (TCP) equation for bioeffect planning is complex with 12 parameters. Consequently, the equation is difficult to implement in practice. Can the equation be simplified by ignoring the variability of some of the parameters? To test this possibility, we have attempted a neural network analysis of the problem. The capability of artificial neural network (ANN) analysis to solve classification problems was explored in which a weight space analysis was conducted. It led to the reduction of the number of parameters. The training data for the ANN analysis was generated using the above equation and practical data from many publications. The performance of the optimized ANN and the reduced-parameter ANN were tested using other treatment data. The optimized ANN results closely matched with those of the

  11. A comparison of different three-dimensional treatment planning techniques for localized radiotherapy of prostate cancer

    International Nuclear Information System (INIS)

    Koswig, S.; Dinges, S.; Buchali, A.; Boehmer, D.; Salk, J.; Rosenthal, P.; Harder, C.; Schlenger, L.; Budach, V.

    1999-01-01

    Purpose: Four different three-dimensional planning techniques for localized radiotherapy of prostate cancer were compared with regard to dose homogeneity within the target volume and dose to organs at risk, dependent upon tumor stage. Patients and Methods: Six patients with stage T1, 7 patients with stage T2 and 4 patients with stage T3 were included in this study. Four different 3D treatment plans (rotation, 4-field, 5-field and 6-field technique) were calculated for each patient. Dose was calculated with the reference point at the isocenter (100%). The planning target volume was encompassed within the 95% isodose surface. All the techniques used different shaped portal for each beam. Dose volume histograms were created and compared for the planning target volume and the organs at risk (33%, 50%, 66% volume level) in all techniques. Results: The 4 different three-dimensional planning techniques revealed no differences concerning dose homogeneity within the planning target volume. The dose volume distribution at organs at risk show differences between the calculated techniques. In our study the best protection for bladder and rectum in stage T1 and T2 was achieved by the 6-field technique. A significant difference was achieved between 6-field and 4-field technique only in the 50% volume of the bladder (p=0.034), between the 6-field and rotation technique (all volume levels) and between 5-field and rotation technique (all volume levels). In stage T1, T2 6-field and 4-field technique in 50% (p-0.033) and 66% (p=0.011) of the rectum volume. In stage T3 a significant difference was not observed between the 4 techniques. The best protection of head of the femur was achieved by the rotation technique. Conclusion: In the localized radiotherapy of prostate cancer in stage T1 or T2 the best protection for bladder and rectum was achieved by a 3D-planned conformal 6-field technique. If the seminal vesicles have been included in the target volume and in the case of large

  12. Navigator channel adaptation to reconstruct three dimensional heart volumes from two dimensional radiotherapy planning data

    International Nuclear Information System (INIS)

    Ng, Angela; Nguyen, Thao-Nguyen; Moseley, Joanne L; Hodgson, David C; Sharpe, Michael B; Brock, Kristy K

    2012-01-01

    Biologically-based models that utilize 3D radiation dosimetry data to estimate the risk of late cardiac effects could have significant utility for planning radiotherapy in young patients. A major challenge arises from having only 2D treatment planning data for patients with long-term follow-up. In this study, we evaluate the accuracy of an advanced deformable image registration (DIR) and navigator channels (NC) adaptation technique to reconstruct 3D heart volumes from 2D radiotherapy planning images for Hodgkin's Lymphoma (HL) patients. Planning CT images were obtained for 50 HL patients who underwent mediastinal radiotherapy. Twelve image sets (6 male, 6 female) were used to construct a male and a female population heart model, which was registered to 23 HL 'Reference' patients' CT images using a DIR algorithm, MORFEUS. This generated a series of population-to-Reference patient specific 3D deformation maps. The technique was independently tested on 15 additional 'Test' patients by reconstructing their 3D heart volumes using 2D digitally reconstructed radiographs (DRR). The technique involved: 1) identifying a matching Reference patient for each Test patient using thorax measurements, 2) placement of six NCs on matching Reference and Test patients' DRRs to capture differences in significant heart curvatures, 3) adapting the population-to-Reference patient-specific deformation maps to generate population-to-Test patient-specific deformation maps using linear and bilinear interpolation methods, 4) applying population-to-Test patient specific deformation to the population model to reconstruct Test-patient specific 3D heart models. The percentage volume overlap between the NC-adapted reconstruction and actual Test patient's true heart volume was calculated using the Dice coefficient. The average Dice coefficient expressed as a percentage between the NC-adapted and actual Test model was 89.4 ± 2.8%. The modified NC adaptation

  13. Feasibility of dose planning using CBCT images combined with MSCT images for adaptive radiotherapy

    International Nuclear Information System (INIS)

    Usui, Keisuke; Kunieda, Etsuo; Ogawa, Koichi

    2013-01-01

    If a kilo-voltage cone-beam computed tomography (CBCT) system mounted on a linear accelerator becomes available for dose calculation, we can confirm the dose distribution of treatment in each day by referring it to the initially planned dose distribution. In this paper, we verified the validity of the calculation method using CBCT images combined with multi-slice CT images. To evaluate the accuracy of calculated dose distribution, γ analysis, distance-to-agreement analysis and dose-volume-histogram analysis were used as the conventional dose calculation methods using CBCT images. The results showed that the dose distribution calculated by our proposed method agreed with the initial treatment plan better compared with the other methods. In addition, our method was so stable that the calculated dose distribution was insensitive to variations in clinical conditions. We demonstrated the feasibility of our proposed method for adaptive radiotherapy. (author)

  14. Determination of two- and three-dimensional radiation fields for neutron radiotherapy planning

    International Nuclear Information System (INIS)

    Boehm, J.K.

    1986-01-01

    The thesis deals with the computerized investigations for fast neutron radiotherapy planning, explaining the calculation and modelling of local dose distributions in patients as a result of mixed neutron and gamma radiation fields. For a computed irradiation program (elaborated for instance by the COMRAD program system), dose distribution functions are required for the simulation of multi-field or moving beam irradiations, the functions being derived semi-empirically by non-linear regression. The necessary data on stationary field doses are derived by measurements or by computed simulation with specific transport programs from the nuclear engineering sector. Transport calculations show the effects of inhomogeneities in the patient's body on the dose distribution. The determined, strong inhomogneity effects (lungs, head) have to be taken into account as precisely as possible in order to achieve optimum irradiation planning. (orig./HP) [de

  15. [Optimization of radiotherapy planning for non-small cell lung cancer (NSCLC) using 18FDG-PET].

    Science.gov (United States)

    Schmidt, S; Nestle, U; Walter, K; Licht, N; Ukena, D; Schnabel, K; Kirsch, C M

    2002-10-01

    In recent years, FDG-PET examinations have become more important for problems in oncology, especially in staging of bronchogenic carcinoma. In the retrospective study presented here, the influence of PET on the planning of radiotherapy for patients with non-small-cell lung cancer (NSCLC) was investigated. The study involved 39 patients with NSCLC who had been examined by PET for staging. They received radiotherapy on the basis of the anterior/posterior portals including the primary tumour and the mediastinum planned according to CT- and bronchoscopic findings. The results of the PET examination were not considered in initial radiotherapy planning. The portals were retrospectively redefined on the basis of FDG uptake considering the size and localization of the primary tumour; and FDG activities outside the mediastinal part of the portals. In 15 out of 39 patients, the CT/PET-planned portals differed from the CT-planned ones. In most causes (n = 12) the CT/PET field was smaller than the CT field. The median geometric field size of the portals was 179 cm2, after redefinition using PET 166 cm2. In 20 patients with disturbed ventilation caused by the tumour (atelectasis, dystelectosis), a correction of the portal was suggested significantly more frequently than in the other patients (p = 0.03). Our results demonstrate the synergism of topographical (CT) and metabolic (FDG-PET) information, which could be helpful in planning radiotherapy of bronchial carcinoma, especially for patients with disturbed ventilation.

  16. Volumetric-modulated arc therapy in postprostatectomy radiotherapy patients: A planning comparison study

    International Nuclear Information System (INIS)

    Forde, Elizabeth; Kneebone, Andrew; Bromley, Regina; Guo, Linxin; Hunt, Peter; Eade, Thomas

    2013-01-01

    The purpose of this study was to compare postprostatectomy planning for volumetric-modulated arc therapy (VMAT) with both single arc (SA) and double arcs (DA) against dynamic sliding window intensity-modulated radiotherapy (IMRT). Ten cases were planned with IMRT, SA VMAT, and DA VMAT. All cases were planned to achieve a minimum dose of 68 Gy to 95% of the planning target volume (PTV) and goals to limit rectal volume >40 Gy to 35% and >65 Gy to 17%, and bladder volumes >40 Gy to 50% and >65 Gy to 25%. Plans were averaged across the 10 patients and compared for mean dose, conformity, homogeneity, rectal and bladder doses, and monitor units. The mean dose to the clinical target volume and PTV was significantly higher (p<0.05) for SA compared with DA or IMRT. The homogeneity index was not significantly different: SA = 0.09; DA = 0.08; and IMRT = 0.07. The rectal V40 was lowest for the DA plan. The rectal V20 was significantly lower (p<0.05) for both the VMAT plans compared with IMRT. There were no significant differences for bladder V40 or rectal and bladder V65. The IMRT plans required 1400 MU compared with 745 for DA and 708 for SA. This study shows that for equivalent dose coverage, SA and DA VMAT plans result in higher mean doses to the clinical target volume and PTV. This greater dose heterogeneity is balanced by improved low-range rectal doses and halving of the monitor units

  17. Volumetric-modulated arc therapy in postprostatectomy radiotherapy patients: A planning comparison study

    Energy Technology Data Exchange (ETDEWEB)

    Forde, Elizabeth, E-mail: eforde@tcd.ie [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Kneebone, Andrew [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Northern Clinical School, University of Sydney, New South Wales (Australia); Bromley, Regina [Institute of Medical Physics, School of Physics, University of Sydney, New South Wales (Australia); Guo, Linxin; Hunt, Peter [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Eade, Thomas [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Northern Clinical School, University of Sydney, New South Wales (Australia)

    2013-10-01

    The purpose of this study was to compare postprostatectomy planning for volumetric-modulated arc therapy (VMAT) with both single arc (SA) and double arcs (DA) against dynamic sliding window intensity-modulated radiotherapy (IMRT). Ten cases were planned with IMRT, SA VMAT, and DA VMAT. All cases were planned to achieve a minimum dose of 68 Gy to 95% of the planning target volume (PTV) and goals to limit rectal volume >40 Gy to 35% and >65 Gy to 17%, and bladder volumes >40 Gy to 50% and >65 Gy to 25%. Plans were averaged across the 10 patients and compared for mean dose, conformity, homogeneity, rectal and bladder doses, and monitor units. The mean dose to the clinical target volume and PTV was significantly higher (p<0.05) for SA compared with DA or IMRT. The homogeneity index was not significantly different: SA = 0.09; DA = 0.08; and IMRT = 0.07. The rectal V40 was lowest for the DA plan. The rectal V20 was significantly lower (p<0.05) for both the VMAT plans compared with IMRT. There were no significant differences for bladder V40 or rectal and bladder V65. The IMRT plans required 1400 MU compared with 745 for DA and 708 for SA. This study shows that for equivalent dose coverage, SA and DA VMAT plans result in higher mean doses to the clinical target volume and PTV. This greater dose heterogeneity is balanced by improved low-range rectal doses and halving of the monitor units.

  18. Bladder radiotherapy treatment: A retrospective comparison of 3-dimensional conformal radiotherapy, intensity-modulated radiation therapy, and volumetric-modulated arc therapy plans

    Energy Technology Data Exchange (ETDEWEB)

    Pasciuti, Katia, E-mail: k.pasciuti@virgilio.it [Department of Radiotherapy Physics, Royal Free Hospital, London (United Kingdom); Kuthpady, Shrinivas [Department of Radiotherapy, Royal Free Hospital, London (United Kingdom); Anderson, Anne; Best, Bronagh [Department of Radiotherapy Physics, Royal Free Hospital, London (United Kingdom); Waqar, Saleem; Chowdhury, Subhra [Department of Radiotherapy, Royal Free Hospital, London (United Kingdom)

    2017-04-01

    To examine tumor's and organ's response when different radiotherapy plan techniques are used. Ten patients with confirmed bladder tumors were first treated using 3-dimensional conformal radiotherapy (3DCRT) and subsequently the original plans were re-optimized using the intensity-modulated radiation treatment (IMRT) and volumetric-modulated arc therapy (VMAT)-techniques. Targets coverage in terms of conformity and homogeneity index, TCP, and organs' dose limits, including integral dose analysis were evaluated. In addition, MUs and treatment delivery times were compared. Better minimum target coverage (1.3%) was observed in VMAT plans when compared to 3DCRT and IMRT ones confirmed by a statistically significant conformity index (CI) results. Large differences were observed among techniques in integral dose results of the femoral heads. Even if no statistically significant differences were reported in rectum and tissue, a large amount of energy deposition was observed in 3DCRT plans. In any case, VMAT plans provided better organs and tissue sparing confirmed also by the normal tissue complication probability (NTCP) analysis as well as a better tumor control probability (TCP) result. Our analysis showed better overall results in planning using VMAT techniques. Furthermore, a total time reduction in treatment observed among techniques including gantry and collimator rotation could encourage using the more recent one, reducing target movements and patient discomfort.

  19. A validation study of the Four-Dimensional Symptom Questionnaire (4DSQ) in insurance medicine

    NARCIS (Netherlands)

    Langerak, W.; Langeland, W.; van Balkom, A.J.L.M.; Draisma, S.; Terluin, B.; Draijer, P.J.

    2012-01-01

    Objective: This study aimed to evaluate the criterion validity and the diagnostic accuracy of the Four-Dimensional Symptom Questionnaire (4DSQ) regarding the identification of depressive and anxiety disorders in an insurance medicine setting. Participants: Our sample consisted of 230 individuals who

  20. Bosonisation of four dimensional real fermionic string models and asymmetric orbifolds

    International Nuclear Information System (INIS)

    Bailin, D.; Dunbar, D.C.; Love, A.

    1990-01-01

    Models of four dimensional strings based on internal world-sheet fermions are bosonised and the partition functions are compared with the partition functions of asymmetric Z 2 M orbifold models. Selection rules and couplings are also compared between the two formations. (orig.)

  1. Energy and angular-momentum non-conservation in four-dimensional gauge theories

    International Nuclear Information System (INIS)

    Manohar, A.

    1985-01-01

    We study energy and angular-momentum non-conservation on four-dimensional chiral gauge theories using Landau levels. These effects are physical manifestations of the usual gauge anomaly, and enable us to understand in a semi-classical approximation why anomaly cancellation is required for a consistent field theory. (orig.)

  2. Quantum theory of string in the four-dimensional space-time

    International Nuclear Information System (INIS)

    Pron'ko, G.P.

    1986-01-01

    The Lorentz invariant quantum theory of string is constructed in four-dimensional space-time. Unlike the traditional approach whose result was breaking of Lorentz invariance, our method is based on the usage of other variables for description of string configurations. The method of an auxiliary spectral problem for periodic potentials is the main tool in construction of these new variables

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

    DEFF Research Database (Denmark)

    Christoffersen, Christian; Hansen, David Christoffer; Poulsen, Per Rugaard

    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...

  4. Spontaneous transition to a stochastic state in a four-dimensional Yang-Mills quantum theory

    International Nuclear Information System (INIS)

    Semikhatov, A.M.

    1983-01-01

    The quantum expectation values in a four-dimensional Yang-Mills theory are represented in each topological sector as expectation values over the diffusion which develops in the ''fourth'' Euclidean time. The Langevin equations of this diffusion are stochastic duality equations in the A 4 = 0 gauge

  5. Adding Four- Dimensional Data Assimilation (a.k.a. grid nudging) to MPAS

    Science.gov (United States)

    Adding four-dimensional data assimilation (a.k.a. grid nudging) to MPAS.The U.S. Environmental Protection Agency is investigating the use of MPAS as the meteorological driver for its next-generation air quality model. To function as such, MPAS needs to operate in a diagnostic mod...

  6. Nonrenormalizable quantum field models in four-dimensional space-time

    International Nuclear Information System (INIS)

    Raczka, R.

    1978-01-01

    The construction of no-cutoff Euclidean Green's functions for nonrenormalizable interactions L/sub I/(phi) = lambda∫ddelta (epsilon): expepsilonphi: in four-dimensional space-time is carried out. It is shown that all axioms for the generating functional of the Euclidean Green's function are satisfied except perhaps SO(4) invariance

  7. The incorporation of SPECT functional lung imaging into inverse radiotherapy planning for non-small cell lung cancer

    International Nuclear Information System (INIS)

    Christian, Judith A.; Partridge, Mike; Nioutsikou, Elena; Cook, Gary; McNair, Helen A.; Cronin, Bernadette; Courbon, Frederic; Bedford, James L.; Brada, Michael

    2005-01-01

    Background and purpose: Patients with non-small cell lung cancer (NSCLC) often have inhomogeneous lung perfusion. Radiotherapy planning computed tomography (CT) scans have been accurately co-registered with lung perfusion single photon emission computed tomography (SPECT) scans to design radiotherapy treatments which limit dose to healthy 'perfused' lung. Patients and methods: Patients with localised NSCLC had CT and SPECT scans accurately co-registered in the planning system. The SPECT images were used to define a volume of perfused 'functioning' lung (FL). Inverse planning software was used to create 3D-conformal plans, the planning objective being either to minimise the dose to whole lungs (WL) or to minimise the dose to FL. Results: Four plans were created for each of six patients. The mean difference in volume between WL and FL was 1011.7 cm 3 (range 596.2-1581.1 cm 3 ). One patient with bilateral upper lobe perfusion deficits had a 16% reduction in FLV 2 (the percentage volume of functioning lung receiving ≥20 Gy). The remaining patients had inhomogeneous perfusion deficits such that inverse planning was not able to sufficiently optimise beam angles to avoid functioning lung. Conclusion: SPECT perfusion images can be accurately co-registered with radiotherapy planning CT scans and may be helpful in creating treatment plans for patients with large perfusion deficits

  8. A DICOM based radiotherapy plan database for research collaboration and reporting

    International Nuclear Information System (INIS)

    Westberg, J; Krogh, S; Brink, C; Vogelius, I R

    2014-01-01

    Purpose: To create a central radiotherapy (RT) plan database for dose analysis and reporting, capable of calculating and presenting statistics on user defined patient groups. The goal is to facilitate multi-center research studies with easy and secure access to RT plans and statistics on protocol compliance. Methods: RT institutions are able to send data to the central database using DICOM communications on a secure computer network. The central system is composed of a number of DICOM servers, an SQL database and in-house developed software services to process the incoming data. A web site within the secure network allows the user to manage their submitted data. Results: The RT plan database has been developed in Microsoft .NET and users are able to send DICOM data between RT centers in Denmark. Dose-volume histogram (DVH) calculations performed by the system are comparable to those of conventional RT software. A permission system was implemented to ensure access control and easy, yet secure, data sharing across centers. The reports contain DVH statistics for structures in user defined patient groups. The system currently contains over 2200 patients in 14 collaborations. Conclusions: A central RT plan repository for use in multi-center trials and quality assurance was created. The system provides an attractive alternative to dummy runs by enabling continuous monitoring of protocol conformity and plan metrics in a trial.

  9. A DICOM based radiotherapy plan database for research collaboration and reporting

    Science.gov (United States)

    Westberg, J.; Krogh, S.; Brink, C.; Vogelius, I. R.

    2014-03-01

    Purpose: To create a central radiotherapy (RT) plan database for dose analysis and reporting, capable of calculating and presenting statistics on user defined patient groups. The goal is to facilitate multi-center research studies with easy and secure access to RT plans and statistics on protocol compliance. Methods: RT institutions are able to send data to the central database using DICOM communications on a secure computer network. The central system is composed of a number of DICOM servers, an SQL database and in-house developed software services to process the incoming data. A web site within the secure network allows the user to manage their submitted data. Results: The RT plan database has been developed in Microsoft .NET and users are able to send DICOM data between RT centers in Denmark. Dose-volume histogram (DVH) calculations performed by the system are comparable to those of conventional RT software. A permission system was implemented to ensure access control and easy, yet secure, data sharing across centers. The reports contain DVH statistics for structures in user defined patient groups. The system currently contains over 2200 patients in 14 collaborations. Conclusions: A central RT plan repository for use in multi-center trials and quality assurance was created. The system provides an attractive alternative to dummy runs by enabling continuous monitoring of protocol conformity and plan metrics in a trial.

  10. Use of Monte Carlo computation in benchmarking radiotherapy treatment planning system algorithms

    International Nuclear Information System (INIS)

    Lewis, R.D.; Ryde, S.J.S.; Seaby, A.W.; Hancock, D.A.; Evans, C.J.

    2000-01-01

    Radiotherapy treatments are becoming more complex, often requiring the dose to be calculated in three dimensions and sometimes involving the application of non-coplanar beams. The ability of treatment planning systems to accurately calculate dose under a range of these and other irradiation conditions requires evaluation. Practical assessment of such arrangements can be problematical, especially when a heterogeneous medium is used. This work describes the use of Monte Carlo computation as a benchmarking tool to assess the dose distribution of external photon beam plans obtained in a simple heterogeneous phantom by several commercially available 3D and 2D treatment planning system algorithms. For comparison, practical measurements were undertaken using film dosimetry. The dose distributions were calculated for a variety of irradiation conditions designed to show the effects of surface obliquity, inhomogeneities and missing tissue above tangential beams. The results show maximum dose differences of 47% between some planning algorithms and film at a point 1 mm below a tangentially irradiated surface. Overall, the dose distribution obtained from film was most faithfully reproduced by the Monte Carlo N-Particle results illustrating the potential of Monte Carlo computation in evaluating treatment planning system algorithms. (author)

  11. Pilot study on virtual imaging for patient information on radiotherapy planning and delivery

    International Nuclear Information System (INIS)

    Sulé-Suso, J.; Finney, S.; Bisson, J.; Hammersley, S.; Jassel, S.; Knight, R.; Hicks, C.; Sargeant, S.; Lam, K.-P.; Belcher, J.; Collins, D.; Bhana, R.; Adab, F.; O'Donovan, C.; Moloney, A.

    2015-01-01

    It is widely accepted that health professionals might sometimes underestimate cancer patients' needs for information on the complex process of radiotherapy (RT) planning and delivery. Furthermore, relatives might also feel excluded from the treatment of their loved ones. This pilot study was carried out in order to assess whether both patients and their relatives would welcome further information on RT planning and delivery using the virtual reality (VR) system VERT. One hundred and fifty patients with different types of cancer receiving radical RT were included in the study. Patients and relatives were shown using VERT on a one-to-one basis with an oncologist or a radiographer, a standard room where RT is given, a linear accelerator, and how RT is planned and delivered using their own planning CT Scans. Patients welcomed this information as it helped them to reduce their fears about RT. Relatives felt also more involved in the treatment of their loved one. The results obtained in this pilot study show that VR aids could become an important tool for delivering information on RT to both patients and relatives. - Highlights: • Virtual imaging helps patients to better understand RT planning and delivery. • Virtual imaging reduces the fear factor. • Virtual imaging improves patients and relatives satisfaction

  12. Discrepancies between selected Pareto optimal plans and final deliverable plans in radiotherapy multi-criteria optimization.

    Science.gov (United States)

    Kyroudi, Archonteia; Petersson, Kristoffer; Ghandour, Sarah; Pachoud, Marc; Matzinger, Oscar; Ozsahin, Mahmut; Bourhis, Jean; Bochud, François; Moeckli, Raphaël

    2016-08-01

    Multi-criteria optimization provides decision makers with a range of clinical choices through Pareto plans that can be explored during real time navigation and then converted into deliverable plans. Our study shows that dosimetric differences can arise between the two steps, which could compromise the clinical choices made during navigation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning

    International Nuclear Information System (INIS)

    Sattler, Bernhard; Lee, John A.; Lonsdale, Markus; Coche, Emmanuel

    2010-01-01

    The positron emission tomography in combination with CT in hybrid, cross-modality imaging systems (PET/CT) gains more and more importance as a part of the treatment-planning procedure in radiotherapy. Positron emission tomography (PET), as a integral part of nuclear medicine imaging and non-invasive imaging technique, offers the visualization and quantification of pre-selected tracer metabolism. In combination with the structural information from CT, this molecular imaging technique has great potential to support and improve the outcome of the treatment-planning procedure prior to radiotherapy. By the choice of the PET-Tracer, a variety of different metabolic processes can be visualized. First and foremost, this is the glucose metabolism of a tissue as well as for instance hypoxia or cell proliferation. This paper comprises the system characteristics of hybrid PET/CT systems. Acquisition and processing protocols are described in general and modifications to cope with the special needs in radiooncology. This starts with the different position of the patient on a special table top, continues with the use of the same fixation material as used for positioning of the patient in radiooncology while simulation and irradiation and leads to special processing protocols that include the delineation of the volumes that are subject to treatment planning and irradiation (PTV, GTV, CTV, etc.). General CT acquisition and processing parameters as well as the use of contrast enhancement of the CT are described. The possible risks and pitfalls the investigator could face during the hybrid-imaging procedure are explained and listed. The interdisciplinary use of different imaging modalities implies a increase of the volume of data created. These data need to be stored and communicated fast, safe and correct. Therefore, the DICOM-Standard provides objects and classes for this purpose (DICOM RT). Furthermore, the standard DICOM objects and classes for nuclear medicine (NM, PT) and

  14. NOTE: Patient-specific planning for prevention of mechanical collisions during radiotherapy

    Science.gov (United States)

    Nioutsikou, Elena; Bedford, James L.; Webb, Steve

    2003-11-01

    A common unwanted difficulty in treatment planning, especially in non-coplanar radiotherapy set-ups, is the potential collision of the rotating gantry with the couch and/or the patient's body. A technique and computer program that detects these and signals avoidance of such beam directions is presented. The problem was approached using analytical geometry. The separate components within the treatment room have either been measured and modelled for an Elekta linear accelerator, or read out from a Pinnacle3 treatment planning system and are represented as an integer grid of points in three-dimensional (3D) space. The module is attached to the treatment planning system and can provide rejection or acceptance of unwanted beam directions in a plan. In contrast to previous work that has only used patient models, each individual patient's outlines are considered here in their actual treatment position inclusive of any immobilization device. The extremities of the patient superiorly and inferiorly to the scanned region are simulated by an expanded version of the RANDO phantom. In this way, 'potential' collisions can be detected in addition to the certain ones. Patient position is not a limiting factor for the accuracy of the collision detection anymore, as each set-up is always created around the isocentre. Maps of allowed and forbidden zones within the treatment suite have been created by running the code for all possible gantry and couch angles for three commonly arising cases: a head and neck plan utilizing a small stereotactic collimator, a prostate plan with multileaf collimators and an abdominal plan with the lead tray attached. In the last case, the 3D map permitted significantly fewer set-up combinations. Good agreement between prediction and experiment confirmed the capability of the program and introduces a promising add-on for treatment planning.

  15. 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.

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

    International Nuclear Information System (INIS)

    Liu, Yilin; Yin, Fang-Fang; Cai, Jing; Chen, Nan-kuei; Chu, Mei-Lan

    2015-01-01

    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 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 p ) and a number of impacting factors: the number of repeated scans (N R ), number of slices (N S ), number of respiratory phase bins (N P ), N KS , F, R, and initial respiratory phase at image acquisition (P 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 p and N R was found best represented by an exponential function (C P =100(1−e −0.18N R ), when N S

  17. Automatic treatment plan re-optimization for adaptive radiotherapy guided with the initial plan DVHs

    International Nuclear Information System (INIS)

    Li, Nan; Zarepisheh, Masoud; Uribe-Sanchez, Andres; Moore, Kevin; Tian, Zhen; Zhen, Xin; Graves, Yan Jiang; Gautier, Quentin; Mell, Loren; Jia, Xun; Jiang, Steve; Zhou, Linghong

    2013-01-01

    Adaptive radiation therapy (ART) can reduce normal tissue toxicity and/or improve tumor control through treatment adaptations based on the current patient anatomy. Developing an efficient and effective re-planning algorithm is an important step toward the clinical realization of ART. For the re-planning process, manual trial-and-error approach to fine-tune planning parameters is time-consuming and is usually considered unpractical, especially for online ART. It is desirable to automate this step to yield a plan of acceptable quality with minimal interventions. In ART, prior information in the original plan is available, such as dose–volume histogram (DVH), which can be employed to facilitate the automatic re-planning process. The goal of this work is to develop an automatic re-planning algorithm to generate a plan with similar, or possibly better, DVH curves compared with the clinically delivered original plan. Specifically, our algorithm iterates the following two loops. An inner loop is the traditional fluence map optimization, in which we optimize a quadratic objective function penalizing the deviation of the dose received by each voxel from its prescribed or threshold dose with a set of fixed voxel weighting factors. In outer loop, the voxel weighting factors in the objective function are adjusted according to the deviation of the current DVH curves from those in the original plan. The process is repeated until the DVH curves are acceptable or maximum iteration step is reached. The whole algorithm is implemented on GPU for high efficiency. The feasibility of our algorithm has been demonstrated with three head-and-neck cancer IMRT cases, each having an initial planning CT scan and another treatment CT scan acquired in the middle of treatment course. Compared with the DVH curves in the original plan, the DVH curves in the resulting plan using our algorithm with 30 iterations are better for almost all structures. The re-optimization process takes about 30

  18. Differences among doses for neuro-axis radiotherapy planning in the gonadal region

    International Nuclear Information System (INIS)

    Lima, F.F de; Vilela, E.C.; Oliveira, F.L.; Filho, J.A.

    2015-01-01

    Radiotherapy can disrupt the functioning of the hypothalamic-pituitary axis, directly causing ovarian deficiencies, such as the decrease in fertility or damage that renders the uterus incapable of accommodating the growth of a fetus. However, these issues have become increasingly important to a growing number of pediatric and adolescent cancer survivors. The whole-body, cranial-spinal axis, as well as abdomen and pelvic region irradiations may expose the ovaries to radiation and may cause premature ovarian failure, whereas doses above 35 Gy cranial can affect the hypothalamic-pituitary functions. This study performed a comparison of four doses of radiotherapy planning techniques for the neural axis. For this analysis, technical simulations were performed for the treatment of medulloblastoma in four different planning, applied in a RANDO anthropomorphic phantom and dosimeters (TLD-100). The radiation fields in the 1”st and 2”nd planning were 40 x 5 cm”2 and 17 x 5 cm”2 with 4.0 cm depth, in which doses were 0.03 and 0.05 Gy / day and 0.11 and 0.09 Gy / days, on the right and left sides, respectively. The 3”rd and 4”th measured planning 32 x 7 cm”2 and 18 x 7 cm”2, with a 2 cm gap and a 4.0 and 5.0 cm depth, in which doses were 1.08 and 0.2 Gy/day and 1.14 and 0.14 Gy/day, on the left and right sides, respectively. It could be observed that the doses in the ovaries in the 3”rd and 4”th schedules proved to be larger than the doses in the 1 s t and 2 n d planning. This is caused by the spinal field width and the depth of the second spinal field, which is 1.0 cm more than the field of the 1”st and 2”nd planning. These differences should be observed in image planning, as incorrect measures can cause damage in the treatment finish. (authors)

  19. The effect of planning algorithms in oesophageal radiotherapy in the context of the SCOPE 1 trial

    International Nuclear Information System (INIS)

    Wills, Lucy; Millin, Anthony; Paterson, Jennifer; Crosby, Tom; Staffurth, John

    2009-01-01

    Background and purpose: In radiotherapy clinical trials multiple centres contribute to patient recruitment. Depending on the calculation algorithm used, the reported dose distributions may differ significantly: broadly, the results for algorithms which do not model lateral electron transport (type a) give less accurate results than the more recently available algorithms that do (type b) when compared to Monte Carlo simulations and measurements. Clinical implementation studies for type b algorithms have yet to be reported for oesophageal radiotherapy. Furthermore, clinical trials must ensure an equivalent effect of the treatment regardless of calculation method. This retrospective planning study aims to define guidance for type b planning in a UK oesophageal clinical trial, to enable acceptable consistency of dose distributions regardless of algorithm, and allow for the improved calculation accuracy of type b to be incorporated into the optimization. Materials and methods: Fifteen patient data sets were planned using a single type a algorithm. Plans were recalculated using a single type b algorithm and subsequently re-optimized with the type b in accordance with optimization rules. The changes in absolute dose at the point of prescription for type a were compared to the recalculated type b. Dose-volume data for organs at risk (OARs), and target volumes were compared, and the volume of the planning target volume (PTV) receiving 95% of the prescribed dose (V95%) was compared to the percentage of PTV overlapping with lung. Results: Dose at the prescription point decreased by 0.69% on average (SD = 0.71), p = 0.0021, for type b compared to that for type a. For the re-optimized type b, the OAR doses corresponding to the trial dose-volume constraints were maintained within 1.0% of the type a levels on average. Reductions in the mean PTV V95% of 9.3% and 3.8% were observed for the recalculated and re-optimized type b plans, respectively, when compared to the mean PTV V95

  20. A dose-volume histogram based decision-support system for dosimetric comparison of radiotherapy treatment plans

    International Nuclear Information System (INIS)

    Alfonso, J. C. L.; Herrero, M. A.; Núñez, L.

    2015-01-01

    The choice of any radiotherapy treatment plan is usually made after the evaluation of a few preliminary isodose distributions obtained from different beam configurations. Despite considerable advances in planning techniques, such final decision remains a challenging task that would greatly benefit from efficient and reliable assessment tools. For any dosimetric plan considered, data on dose-volume histograms supplied by treatment planning systems are used to provide estimates on planning target coverage as well as on sparing of organs at risk and the remaining healthy tissue. These partial metrics are then combined into a dose distribution index (DDI), which provides a unified, easy-to-read score for each competing radiotherapy plan. To assess the performance of the proposed scoring system, DDI figures for fifty brain cancer patients were retrospectively evaluated. Patients were divided in three groups depending on tumor location and malignancy. For each patient, three tentative plans were designed and recorded during planning, one of which was eventually selected for treatment. We thus were able to compare the plans with better DDI scores and those actually delivered. When planning target coverage and organs at risk sparing are considered as equally important, the tentative plan with the highest DDI score is shown to coincide with that actually delivered in 32 of the 50 patients considered. In 15 (respectively 3) of the remaining 18 cases, the plan with highest DDI value still coincides with that actually selected, provided that organs at risk sparing is given higher priority (respectively, lower priority) than target coverage. DDI provides a straightforward and non-subjective tool for dosimetric comparison of tentative radiotherapy plans. In particular, DDI readily quantifies differences among competing plans with similar-looking dose-volume histograms and can be easily implemented for any tumor type and localization, irrespective of the planning system and

  1. The Impact of Colleague Peer Review on the Radiotherapy Treatment Planning Process in the Radical Treatment of Lung Cancer.

    Science.gov (United States)

    Rooney, K P; McAleese, J; Crockett, C; Harney, J; Eakin, R L; Young, V A L; Dunn, M A; Johnston, R E; Hanna, G G

    2015-09-01

    Modern radiotherapy uses techniques to reliably identify tumour and reduce target volume margins. However, this can potentially lead to an increased risk of geographic miss. One source of error is the accuracy of target volume delineation (TVD). Colleague peer review (CPR) of all curative-intent lung cancer plans has been mandatory in our institution since May 2013. At least two clinical oncologists review plans, checking treatment paradigm, TVD, prescription dose tumour and critical organ tolerances. We report the impact of CPR in our institution. Radiotherapy treatment plans of all patients receiving radical radiotherapy were presented at weekly CPR meetings after their target volumes were reviewed and signed off by the treating consultant. All cases and any resultant change to TVD (including organs at risk) or treatment intent were recorded in our prospective CPR database. The impact of CPR over a 13 month period from May 2013 to June 2014 is reported. One hundred and twenty-two patients (63% non-small cell lung carcinoma, 17% small cell lung carcinoma and 20% 'clinical diagnosis') were analysed. On average, 3.2 cases were discussed per meeting (range 1-8). CPR resulted in a change in treatment paradigm in 3% (one patient proceeded to induction chemotherapy, two patients had high-dose palliative radiotherapy). Twenty-one (17%) had a change in TVD and one (1%) patient had a change in dose prescription. In total, 6% of patients had plan adjustment after review of dose volume histogram. The introduction of CPR in our centre has resulted in a change in a component of the treatment plan for 27% of patients receiving curative-intent lung radiotherapy. We recommend CPR as a mandatory quality assurance step in the planning process of all radical lung plans. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  2. Differences in abdominal organ movement between supine and prone positions measured using four-dimensional computed tomography

    International Nuclear Information System (INIS)

    Kim, Young Seok; Park, Sung Ho; Ahn, Seung Do; Lee, Jeong Eun; Choi, Eun Kyung; Lee, Sang-wook; Shin, Seong Soo; Yoon, Sang Min; Kim, Jong Hoon

    2007-01-01

    Background and purpose: To analyze the differences in intrafractional organ movement throughout the breathing cycles between the supine and prone positions using four-dimensional computed tomography (4D CT). Materials and methods: We performed 4D CT on nine volunteers in the supine and prone positions, with each examinee asked to breathe normally during scanning. The movement of abdominal organs in the cranio-caudal (CC), anterior-posterior (AP) and right-left (RL) directions was quantified by contouring on each phase between inspiration and expiration. Results: The mean intrafractional motions of the hepatic dome, lower tip, pancreatic head and tail, both kidneys, spleen, and celiac axis in the supine/prone position were 17.3/13.0, 14.4/11.0, 12.8/8.9, 13.0/10.0, 14.3/12.1, 12.3/12.6, 11.7/12.6 and 2.2/1.8 mm, respectively. Intrafractional movements of the liver dome and pancreatic head were reduced significantly in the prone position. The CC directional excursions were major determinants of the 3D displacements of the abdominal organs. Alteration from the supine to the prone position did not change the amount of intrafractional movements of kidneys, spleen, and celiac axis. Conclusion: There was a significant reduction in the movements of the liver and pancreas during the prone position, especially in the CC direction, suggesting possible advantage of radiotherapy to these organs in this position

  3. A treatment planning comparison of four target volume contouring guidelines for locally advanced pancreatic cancer radiotherapy

    International Nuclear Information System (INIS)

    Fokas, Emmanouil; Eccles, Cynthia; Patel, Neel; Chu, Kwun-Ye; Warren, Samantha; McKenna, W. Gillies; Brunner, Thomas B.

    2013-01-01

    Background and purpose: Contouring of target volumes varies significantly in radiotherapy of pancreatic ductal adenocarcinoma (PDAC). There is a lack of consensus as to whether elective lymph nodes (eLN’s) should be included or not in the planning target volume (PTV). In the present study we analyzed the dosimetric coverage of the eLN’s and organs at risk (OAR) by comparing four different contouring guidelines. Methods and materials: PTVs were delineated with (Oxford and RTOG guidelines) or without (Michigan and SCALOP guidelines) including the eLNs in eleven patients with PDAC. eLNs included the peripancreatic, paraaortic, paracaval, celiac trunk, superior mesenteric and portal vein clinical target volumes (CTVs). A 3D-CRT plan (50.40 Gy in 28 fractions) was performed to analyze and compare the dosimetric coverage of all eLNs and OAR between the 4 contouring guidelines. Results: The size of Oxford and RTOG PTVs was comparable and significantly larger than the SCALOP and Michigan PTVs. Interestingly the eLNs received a significant amount of incidental dose irradiation by PTV-based plans that only aimed to treat the tumor without the eLNs. The dosimetric coverage of eLN presented a large variability according to the respective contouring methods. The difference in the size of the 4 PTVs was reflected to the dose distribution at the OAR. Conclusions: Our study provides important information regarding the impact of different contouring guidelines on the dose distribution to the eLNs and the OAR in patients with locally advanced PDAC treated with radiotherapy

  4. Quality control in health care: an experiment in radiotherapy planning for breast cancer patients after mastectomy

    International Nuclear Information System (INIS)

    Holli, Kaija; Laippala, Pekka; Ojala, Antti; Pitkaenen, Maunu

    1999-01-01

    Purpose: The importance of evaluating and improving quality in clinical practice is now generally acknowledged. In this study we estimated different sources of variation in radiotherapy planning for breast cancer patients after mastectomy and sought to test the applicability of a reproducibility and repeatability (R and R) study in a clinical context. Methods: Eleven radiation oncologists planned radiotherapy three times for three different kinds of breast cancer patients without knowing they were handling the same patient three times. Variation was divided into different components: physicians as operators, patients as parts, and repeated measurements as trials. Variation due to difference across trials (repeatability), that across the physicians (reproducibility), and that across the patients (variability) were estimated, as well as interactions between physicians and patients. Calculation was based on the sum of squares, and analysis was supported by various graphical presentations such as range charts and box plots. Results: Some parts of the planning process were characterized by higher and different kinds of variation than the others. Interphysician variation (i.e., reproducibility) was not high but there were some clearly outlying physicians. The highest variation was in repeatability (intraphysician variation). The major part of the variation was, however, that from patient to patient: 33% of the total in Parameter 1 and 85% of the total in Parameter 2. Conclusions: R and R studies are applicable and are needed to evaluate and improve quality in clinical practice. This kind of analysis provides opportunities to establish which kinds of patients require particularly careful attention, which points in the process are most critical for variation, which are the most difficult aspects for each physician and call for more careful description in documents, and which physicians need further training

  5. Auditing local methods for quality assurance in radiotherapy using the same set of predefined treatment plans

    Directory of Open Access Journals (Sweden)

    Enrica Seravalli

    2018-01-01

    Full Text Available Background and purpose: Local implementation of plan-specific quality assurance (QA methods for intensity-modulated radiotherapy (IMRT and volumetric modulated arc therapy (VMAT treatment plans may vary because of dissimilarities in procedures, equipment and software. The purpose of this work is detecting possible differences between local QA findings and those of an audit, using the same set of treatment plans. Methods: A pre-defined set of clinical plans was devised and imported in the participating institute’s treatment planning system for dose computation. The dose distribution was measured using an ionisation chamber, radiochromic film and an ionisation chamber array. The centres performed their own QA, which was compared to the audit findings. The agreement/disagreement between the audit and the institute QA results were assessed along with the differences between the dose distributions measured by the audit team and computed by the institute. Results: For the majority of the cases the results of the audit were in agreement with the institute QA findings: ionisation chamber: 92%, array: 88%, film: 76% of the total measurements. In only a few of these cases the evaluated measurements failed for both: ionisation chamber: 2%, array: 4%, film: 0% of the total measurements. Conclusion: Using predefined treatment plans, we found that in approximately 80% of the evaluated measurements the results of local QA of IMRT and VMAT plans were in line with the findings of the audit. However, the percentage of agreement/disagreement depended on the characteristics of the measurement equipment used and on the analysis metric. Keywords: Quality assurance, Dosimetry audit, IMRT, VMAT, QA devices

  6. FoCa: a modular treatment planning system for proton radiotherapy with research and educational purposes.

    Science.gov (United States)

    Sánchez-Parcerisa, D; Kondrla, M; Shaindlin, A; Carabe, A

    2014-12-07

    FoCa is an in-house modular treatment planning system, developed entirely in MATLAB, which includes forward dose calculation of proton radiotherapy plans in both active and passive modalities as well as a generic optimization suite for inverse treatment planning. The software has a dual education and research purpose. From the educational point of view, it can be an invaluable teaching tool for educating medical physicists, showing the insights of a treatment planning system from a well-known and widely accessible software platform. From the research point of view, its current and potential uses range from the fast calculation of any physical, radiobiological or clinical quantity in a patient CT geometry, to the development of new treatment modalities not yet available in commercial treatment planning systems. The physical models in FoCa were compared with the commissioning data from our institution and show an excellent agreement in depth dose distributions and longitudinal and transversal fluence profiles for both passive scattering and active scanning modalities. 3D dose distributions in phantom and patient geometries were compared with a commercial treatment planning system, yielding a gamma-index pass rate of above 94% (using FoCa's most accurate algorithm) for all cases considered. Finally, the inverse treatment planning suite was used to produce the first prototype of intensity-modulated, passive-scattered proton therapy, using 13 passive scattering proton fields and multi-leaf modulation to produce a concave dose distribution on a cylindrical solid water phantom without any field-specific compensator.

  7. Pelvic Radiotherapy for Cancer of the Cervix: Is What You Plan Actually What You Deliver?

    International Nuclear Information System (INIS)

    Lim, Karen; Kelly, Valerie; Stewart, James; Xie, Jason; Cho, Young-Bin; Moseley, Joanne B.; Brock, Kristy; Fyles, Anthony; Lundin, Anna; Rehbinder, Henrik; Milosevic, Michael

    2009-01-01

    Purpose: Whole pelvic intensity-modulated radiotherapy (IMRT) is increasingly being used to treat cervix cancer and other gynecologic tumors. However, tumor and normal organ movement during treatment can substantially detract from the benefits of this approach. This study explored the effect of internal anatomic changes on the dose delivered to the tumor and organs at risk using a strategy integrating deformable soft-tissue modeling with simulated dose accumulation. Methods and Materials: Twenty patients with cervix cancer underwent baseline and weekly pelvic magnetic resonance imaging during treatment. Interfraction organ motion and delivered (accumulated) dose was modeled for three treatment scenarios: four-field box, large-margin whole pelvic IMRT (20-mm planning target volume, but 10 mm inferiorly) and small-margin IMRT (5-mm planning target volume). Results: Individually, the planned dose was not the same as the simulated delivered dose; however, when taken as a group, this was not statistically significant for the four-field box and large-margin IMRT plans. The small-margin IMRT plans yielded adequate target coverage in most patients; however, significant target underdosing occurred in 1 patient who displayed excessive, unpredictable internal target movement. The delivered doses to the organs at risk were significantly reduced with the small-margin plan, although substantial variability was present among the patients. Conclusion: Simulated dose accumulation might provide a more accurate depiction of the target and organ at risk coverage during fractionated whole pelvic IMRT for cervical cancer. The adequacy of primary tumor coverage using 5-mm planning target volume margins is contingent on the use of daily image-guided setup.

  8. 18F-Fdg-PET-guided Planning and Re-Planning (Adaptive) Radiotherapy in Head and Neck Cancer: Current State of Art.

    Science.gov (United States)

    Farina, Eleonora; Ferioli, Martina; Castellucci, Paolo; Farina, Arianna; Zanirato Rambaldi, Giuseppe; Cilla, Savino; Cammelli, Silvia; Fanti, Stefano; Morganti, Alessio G

    2017-12-01

    A review of the literature is proposed as a contribution to current knowledge on technical, physical, and clinical issues about PET-guided planning and re-planning radiotherapy (RT) in head and neck cancer. PubMed and Scopus electronic databases were searched for articles including clinical trials. Search terms were "gross tumor volume (GTV) delineation", "head and neck cancer", "radiotherapy", "adaptive radiotherapy" in combination with "PET". A 18 F-FDG-PET and CT-scan comparison in GTV definition for RT planning of head and neck cancer was shown in twenty-seven clinical trials with a total of 712 patients. Only two clinical trials focused on PET-guided adaptive radiotherapy (ART) with a total of 31 patients. 18 F-FDG-PET is able to achieve an accurate and precise definition of GTV boundaries during RT planning, especially in combination with CT-scan. ART strategies are proposed to evaluate tumor volume changes, plan boost irradiation on metabolically active residual neoplasm and protect organs at risk (OaRs). Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  9. MMCTP: a radiotherapy research environment for Monte Carlo and patient-specific treatment planning

    International Nuclear Information System (INIS)

    Alexander, A; DeBlois, F; Stroian, G; Al-Yahya, K; Heath, E; Seuntjens, J

    2007-01-01

    Radiotherapy research lacks a flexible computational research environment for Monte Carlo (MC) and patient-specific treatment planning. The purpose of this study was to develop a flexible software package on low-cost hardware with the aim of integrating new patient-specific treatment planning with MC dose calculations suitable for large-scale prospective and retrospective treatment planning studies. We designed the software package 'McGill Monte Carlo treatment planning' (MMCTP) for the research development of MC and patient-specific treatment planning. The MMCTP design consists of a graphical user interface (GUI), which runs on a simple workstation connected through standard secure-shell protocol to a cluster for lengthy MC calculations. Treatment planning information (e.g., images, structures, beam geometry properties and dose distributions) is converted into a convenient MMCTP local file storage format designated, the McGill RT format. MMCTP features include (a) DICOM R T, RTOG and CADPlan CART format imports; (b) 2D and 3D visualization views for images, structure contours, and dose distributions; (c) contouring tools; (d) DVH analysis, and dose matrix comparison tools; (e) external beam editing; (f) MC transport calculation from beam source to patient geometry for photon and electron beams. The MC input files, which are prepared from the beam geometry properties and patient information (e.g., images and structure contours), are uploaded and run on a cluster using shell commands controlled from the MMCTP GUI. The visualization, dose matrix operation and DVH tools offer extensive options for plan analysis and comparison between MC plans and plans imported from commercial treatment planning systems. The MMCTP GUI provides a flexible research platform for the development of patient-specific MC treatment planning for photon and electron external beam radiation therapy. The impact of this tool lies in the fact that it allows for systematic, platform

  10. Clinical trials radiotherapy treatment plan review software : is this the first quantified assessment

    International Nuclear Information System (INIS)

    Hatton, J.A.; Cornes, D.A.

    2011-01-01

    Full text: Clinical trials require robust quality assurance (QA) procedures to ensure commonality of all treatments, with independent reviews to assess compliance with trial protocols. All clinical trials tools, including QA software, require testing for validity and reliability. enabling inter- and intra-trial comparison. Unlike clinical radiotherapy treatment planning (RTP) systems, review software has no published guidelines. This study describes the design and development of a test suite to quantify the performance of review software in TROG clinical trials. Test areas are image handling and reconstruction; geometric accuracy; dosimetric accuracy; dose-volume histogram (DVH) calculation; display of plan parameters. TROG have developed tests for commissioning plan review software, assessed with SWAN 2.3, and CMS Elekta FocalPro. While image handling tests were based on published guidelines for RTP systems, dosimetric tests used the TROG QA case review requirements. Treatment plans represented systems of all manufacturers (Pinnacle, Eclipse, Xio and Oncentra) used in Australasian centres. The test suite identified areas for SW A software development, including the DVH algorithm, changed to reduce calculation time. Results, in Fig. I, for known volumes of varying shapes and sizes, demonstrate differences between SWAN 2.1 and 2.3 when compared with Eclipse. Liaison with SWAN programmers enabled re-instatement of 2.1 algorithm. The test suite has quantified the RTP review software, prioritised areas for development with the programmers, and improved the user experience.

  11. Treatment planning for heavy ion radiotherapy: physical beam model and dose optimization

    International Nuclear Information System (INIS)

    Kraemer, M.; Haberer, T.; Kraft, G.; Schardt, D.; Weber, U.

    2000-09-01

    We describe a novel code system, TRiP, dedicated to the planning of radiotherapy with energetic ions, in particular 12 C. The software is designed to cooperate with three-dimensional active dose shaping devices like the GSI raster scan system. This unique beam delivery system allows to select any combination from a list of 253 individual beam energies, 7 different beam spot sizes and 15 intensity levels. The software includes a beam model adapted to and verified for carbon ions. Inverse planning techniques are implemented in order to obtain a uniform target dose distribution from clinical input data, i.e. CT images and patient contours. This implies the automatic generation of intensity modulated fields of heavy ions with as many as 40000 raster points, where each point corresponds to a specific beam position, energy and particle fluence. This set of data is directly passed to the beam delivery and control system. The treatment planning code is in clinical use since the start of the GSI pilot project in December 1997. To this end 48 patients have been successfully planned and treated. (orig.)

  12. Megavoltage conebeam CT cine as final verification of treatment plan in lung stereotactic body radiotherapy

    International Nuclear Information System (INIS)

    Kudithipudi, Vijay; Gayou, Olivier; Colonias, Athanasios

    2016-01-01

    To analyse the clinical impact of megavoltage conebeam computed tomography (MV-CBCT) cine on internal target volume (ITV) coverage in lung stereotactic body radiotherapy (SBRT). One hundred and six patients received lung SBRT. All underwent 4D computed tomography simulation followed by treatment via image guided 3D conformal or intensity modulated radiation. Prior to SBRT, all patients underwent MV-CBCT cine, in which raw projections are displayed as beam's-eye-view fluoroscopic series with the planning target volume (PTV) projected onto each image, enabling verification of tumour motion relative to the PTV and assessment of adequacy of treatment margin. Megavoltage conebeam computed tomography cine was completed 1–2 days prior to SBRT. Four patients (3.8%) had insufficient ITV coverage inferiorly at cine review. All four plans were changed by adding 5 mm on the PTV margin inferiorly. The mean change in PTV volumes was 3.9 cubic centimetres (cc) (range 1.85–6.32 cc). Repeat cine was performed after plan modification to ensure adequate PTV coverage in the modified plans. PTV margin was adequate in the majority of patients with this technique. MV-CBCT cine did show insufficient coverage in a small subset of patients. Insufficient PTV margins may be a function of 4D CT simulation inadequacies or deficiencies in visualizing the ITV inferior border in the full-inhale phase. MV-CBCT cine is a valuable tool for final verification of PTV margins.

  13. Radiographer-led plan selection for bladder cancer radiotherapy: initiating a training programme and maintaining competency.

    Science.gov (United States)

    McNair, H A; Hafeez, S; Taylor, H; Lalondrelle, S; McDonald, F; Hansen, V N; Huddart, R

    2015-04-01

    The implementation of plan of the day selection for patients receiving radiotherapy (RT) for bladder cancer requires efficient and confident decision-making. This article describes the development of a training programme and maintenance of competency. Cone beam CT (CBCT) images acquired on patients receiving RT for bladder cancer were assessed to establish baseline competency and training needs. A training programme was implemented, and observers were asked to select planning target volumes (PTVs) on two groups of 20 patients' images. After clinical implementation, the PTVs chosen were reviewed offline, and an audit performed after 3 years. A mean of 73% (range, 53-93%) concordance rate was achieved prior to training. Subsequent to training, the mean score decreased to 66% (Round 1), then increased to 76% (Round 2). Six radiographers and two clinicians successfully completed the training programme. An independent observer reviewed the images offline after clinical implementation, and a 91% (126/139) concordance rate was achieved. During the audit, 125 CBCT images from 13 patients were reviewed by a single observer and concordance was 92%. Radiographer-led selection of plan of the day was implemented successfully with the use of a training programme and continual assessment. Quality has been maintained over a period of 3 years. The training programme was successful in achieving and maintaining competency for a plan of the day technique.

  14. Treatment planning for heavy-ion radiotherapy: physical beam model and dose optimization

    Science.gov (United States)

    Krämer, M.; Jäkel, O.; Haberer, T.; Kraft, G.; Schardt, D.; Weber, U.

    2000-11-01

    We describe a novel code system, TRiP, dedicated to the planning of radiotherapy with energetic ions, in particular 12C. The software is designed to cooperate with three-dimensional active dose shaping devices like the GSI raster scan system. This unique beam delivery system allows us to select any combination from a list of 253 individual beam energies, 7 different beam spot sizes and 15 intensity levels. The software includes a beam model adapted to and verified for carbon ions. Inverse planning techniques are implemented in order to obtain a uniform target dose distribution from clinical input data, i.e. CT images and patient contours. This implies the automatic generation of intensity modulated fields of heavy ions with as many as 40 000 raster points, where each point corresponds to a specific beam position, energy and particle fluence. This set of data is directly passed to the beam delivery and control system. The treatment planning code has been in clinical use since the start of the GSI pilot project in December 1997. Forty-eight patients have been successfully planned and treated.

  15. Technical aspects of positron emission tomography/computed tomography in radiotherapy treatment planning.

    Science.gov (United States)

    Scripes, Paola G; Yaparpalvi, Ravindra

    2012-09-01

    The usage of functional data in radiation therapy (RT) treatment planning (RTP) process is currently the focus of significant technical, scientific, and clinical development. Positron emission tomography (PET) using ((18)F) fluorodeoxyglucose is being increasingly used in RT planning in recent years. Fluorodeoxyglucose is the most commonly used radiotracer for diagnosis, staging, recurrent disease detection, and monitoring of tumor response to therapy (Lung Cancer 2012;76:344-349; Lung Cancer 2009;64:301-307; J Nucl Med 2008;49:532-540; J Nucl Med 2007;48:58S-67S). All the efforts to improve both PET and computed tomography (CT) image quality and, consequently, lesion detectability have a common objective to increase the accuracy in functional imaging and thus of coregistration into RT planning systems. In radiotherapy, improvement in target localization permits reduction of tumor margins, consequently reducing volume of normal tissue irradiated. Furthermore, smaller treated target volumes create the possibility of dose escalation, leading to increased chances of tumor cure and control. This article focuses on the technical aspects of PET/CT image acquisition, fusion, usage, and impact on the physics of RTP. The authors review the basic elements of RTP, modern radiation delivery, and the technical parameters of coregistration of PET/CT into RT computerized planning systems. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. A method for generating large datasets of organ geometries for radiotherapy treatment planning studies

    International Nuclear Information System (INIS)

    Hu, Nan; Cerviño, Laura; Segars, Paul; Lewis, John; Shan, Jinlu; Jiang, Steve; Zheng, Xiaolin; Wang, Ge

    2014-01-01

    With the rapidly increasing application of adaptive radiotherapy, large datasets of organ geometries based on the patient’s anatomy are desired to support clinical application or research work, such as image segmentation, re-planning, and organ deformation analysis. Sometimes only limited datasets are available in clinical practice. In this study, we propose a new method to generate large datasets of organ geometries to be utilized in adaptive radiotherapy. Given a training dataset of organ shapes derived from daily cone-beam CT, we align them into a common coordinate frame and select one of the training surfaces as reference surface. A statistical shape model of organs was constructed, based on the establishment of point correspondence between surfaces and non-uniform rational B-spline (NURBS) representation. A principal component analysis is performed on the sampled surface points to capture the major variation modes of each organ. A set of principal components and their respective coefficients, which represent organ surface deformation, were obtained, and a statistical analysis of the coefficients was performed. New sets of statistically equivalent coefficients can be constructed and assigned to the principal components, resulting in a larger geometry dataset for the patient’s organs. These generated organ geometries are realistic and statistically representative

  17. 18 F-FDG PET/CT for planning external beam radiotherapy alters therapy in 11% of 581 patients.

    Science.gov (United States)

    Birk Christensen, Charlotte; Loft-Jakobsen, Annika; Munck Af Rosenschöld, Per; Højgaard, Liselotte; Roed, Henrik; Berthelsen, Anne K

    2018-03-01

    18 F-FDG PET/CT (FDG PET/CT) used in radiotherapy planning for extra-cerebral malignancy may reveal metastases to distant sites that may affect the choice of therapy. To investigate the role of FDG PET/CT on treatment strategy changes induced by the use of PET/CT as part of the radiotherapy planning. 'A major change of treatment strategy' was defined as either including more lesions in the gross tumour volume (GTV) distant from the primary tumour or a change in treatment modalities. The study includes 581 consecutive patients who underwent an FDG PET/CT scan for radiotherapy planning in our institution in the year 2008. All PET/CT scans were performed with the patient in treatment position with the use of immobilization devices according to the intended radiotherapy treatment. All scans were evaluated by a nuclear medicine physician together with a radiologist to delineate PET-positive GTV (GTV-PET). For 63 of the patients (11%), the PET/CT simulation scans resulted in a major change in treatment strategy because of the additional diagnostic information. Changes were most frequently observed in patients with lung cancer (20%) or upper gastrointestinal cancer (12%). In 65% of the patients for whom the PET/CT simulation scan revealed unexpected dissemination, radiotherapy was given - changed (n = 38) or unchanged (n = 13) according to the findings on the FDG PET/CT. Unexpected dissemination on the FDG PET/CT scanning performed for radiotherapy planning caused a change in treatment strategy in 11% of 581 patients. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  18. Use of Respiratory-Correlated Four-Dimensional Computed Tomography to Determine Acceptable Treatment Margins for Locally Advanced Pancreatic Adenocarcinoma

    International Nuclear Information System (INIS)

    Goldstein, Seth D.; Ford, Eric C.; Duhon, Mario; McNutt, Todd; Wong, John; Herman, Joseph M.

    2010-01-01

    Purpose: Respiratory-induced excursions of locally advanced pancreatic adenocarcinoma could affect dose delivery. This study quantified tumor motion and evaluated standard treatment margins. Methods and Materials: Respiratory-correlated four-dimensional computed tomography images were obtained on 30 patients with locally advanced pancreatic adenocarcinoma; 15 of whom underwent repeat scanning before cone-down treatment. Treatment planning software was used to contour the gross tumor volume (GTV), bilateral kidneys, and biliary stent. Excursions were calculated according to the centroid of the contoured volumes. Results: The mean ± standard deviation GTV excursion in the superoinferior (SI) direction was 0.55 ± 0.23 cm; an expansion of 1.0 cm adequately accounted for the GTV motion in 97% of locally advanced pancreatic adenocarcinoma patients. Motion GTVs were generated and resulted in a 25% average volume increase compared with the static GTV. Of the 30 patients, 17 had biliary stents. The mean SI stent excursion was 0.84 ± 0.32 cm, significantly greater than the GTV motion. The xiphoid process moved an average of 0.35 ± 0.12 cm, significantly less than the GTV. The mean SI motion of the left and right kidneys was 0.65 ± 0.27 cm and 0.77 ± 0.30 cm, respectively. At repeat scanning, no significant changes were seen in the mean GTV size (p = .8) or excursion (p = .3). Conclusion: These data suggest that an asymmetric expansion of 1.0, 0.7, and 0.6 cm along the respective SI, anteroposterior, and medial-lateral directions is recommended if a respiratory-correlated four-dimensional computed tomography scan is not available to evaluate the tumor motion during treatment planning. Surrogates of tumor motion, such as biliary stents or external markers, should be used with caution.

  19. Treatment-Planning Study of Prostate Cancer Intensity-Modulated Radiotherapy With a Varian Clinac Operated Without a Flattening Filter

    International Nuclear Information System (INIS)

    Vassiliev, Oleg N.; Kry, Stephen F.; Kuban, Deborah A.; Salehpour, Mohammad; Mohan, Radhe; Titt, Uwe

    2007-01-01

    Purpose: To assess the feasibility of intensity-modulated radiotherapy for prostate cancer using photon beams from an accelerator operated without a flattening filter; and to determine potential benefits and drawbacks of using unflattened beams for this type of treatment. Methods and Materials: Intensity-modulated radiotherapy plans were generated for 10 patients with early-stage prostate cancer. For each patient, four plans were generated: with and without the flattening filter, at 6 and 18 MV. The prescription dose was 75.6 Gy to 98% of the planning target volume. The number of beams, their orientations, and optimization constraints were the same for all plans. Plans were generated with Eclipse 8.0 (Varian Medical Systems). Results: All the plans developed with unflattened beams were clinically acceptable. In terms of patient dose distributions, plans with unflattened beams were similar to the corresponding plans with flattened beams. Plans with unflattened beams required fewer monitor units (MUs) per plan: on average, by a factor of 2.0 at 6 MV and 2.6 at 18 MV, assuming that removal of the flattening filter was not followed by recalibration of MUs. Conclusions: Clinically acceptable intensity-modulated radiotherapy plans for prostate cancer can be developed with unflattened beams at both 6 and 18 MV. Dosimetrically, flattened and unflattened beams generated similar treatment plans. The plans with unflattened beams required substantially fewer MUs. The reduction in the number of MUs indicates corresponding reduction in beam-on time and in the amount of radiation outside the target

  20. Evaluation of the perturbation of the mesh Bra Breast TiLoop in the planning process-radiotherapy

    International Nuclear Information System (INIS)

    Camacho, C.; Pujades, M. C.; Perez-Calatayud, J.; Lliso, F.; Carmona, V.; Richart, J.; Ballester, F.

    2011-01-01

    The aim of this study is to determine the dosimetric impact TiLoop Mesh Bra breast radiotherapy treatments, and their influence on both the quality and the disruption of the gray levels of the radiographic image required for treatment planning.

  1. Magnetic resonance imaging for radiotherapy planning of brain cancer patients using immobilization and surface coils

    Science.gov (United States)

    Hanvey, S.; Glegg, M.; Foster, J.

    2009-09-01

    This study investigated the compatibility of a head and neck immobilization device with magnetic resonance imaging (MRI). The immobilization device is used to position a patient in the same way as when receiving a computed tomography (CT) scan for radiotherapy planning and radiation treatment. The advantage of using immobilization in MR is improved accuracy in CT/MR image registration enabling greater confidence in the delineation of structures. The main practical difficulty in using an immobilization device in MRI is that physical constraints make their use incompatible with head imaging coils. Within this paper we describe a method for MR imaging of the brain which allows the use of head and neck immobilization devices. By a series of image quality tests we obtained the same or better image quality as a multi-channel head coil.

  2. An optimized workflow for the integration of biological information into radiotherapy planning: experiences with T1w DCE-MRI

    International Nuclear Information System (INIS)

    Neff, T; Kiessling, F; Brix, G; Baudendistel, K; Zechmann, C; Giesel, F L; Bendl, R

    2005-01-01

    Planning of radiotherapy is often difficult due to restrictions on morphological images. New imaging techniques enable the integration of biological information into treatment planning and help to improve the detection of vital and aggressive tumour areas. This might improve clinical outcome. However, nowadays morphological data sets are still the gold standard in the planning of radiotherapy. In this paper, we introduce an in-house software platform enabling us to combine images from different imaging modalities yielding biological and morphological information in a workflow driven approach. This is demonstrated for the combination of morphological CT, MRI, functional DCE-MRI and PET data. Data of patients with a tumour of the prostate and with a meningioma were examined with DCE-MRI by applying pharmacokinetic two-compartment models for post-processing. The results were compared with the clinical plans for radiation therapy. Generated parameter maps give additional information about tumour spread, which can be incorporated in the definition of safety margins

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

    International Nuclear Information System (INIS)

    Li Chongguo; Wu Dake

    2012-01-01

    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)

  4. Four-dimensional volume-of-interest reconstruction for cone-beam computed tomography-guided radiation therapy.

    Science.gov (United States)

    Ahmad, Moiz; Balter, Peter; Pan, Tinsu

    2011-10-01

    Data sufficiency are a major problem in four-dimensional cone-beam computed tomography (4D-CBCT) on linear accelerator-integrated scanners for image-guided radiotherapy. Scan times must be in the range of 4-6 min to avoid undersampling artifacts. Various image reconstruction algorithms have been proposed to accommodate undersampled data acquisitions, but these algorithms are computationally expensive, may require long reconstruction times, and may require algorithm parameters to be optimized. The authors present a novel reconstruction method, 4D volume-of-interest (4D-VOI) reconstruction which suppresses undersampling artifacts and resolves lung tumor motion for undersampled 1-min scans. The 4D-VOI reconstruction is much less computationally expensive than other 4D-CBCT algorithms. The 4D-VOI method uses respiration-correlated projection data to reconstruct a four-dimensional (4D) image inside a VOI containing the moving tumor, and uncorrelated projection data to reconstruct a three-dimensional (3D) image outside the VOI. Anatomical motion is resolved inside the VOI and blurred outside the VOI. The authors acquired a 1-min. scan of an anthropomorphic chest phantom containing a moving water-filled sphere. The authors also used previously acquired 1-min scans for two lung cancer patients who had received CBCT-guided radiation therapy. The same raw data were used to test and compare the 4D-VOI reconstruction with the standard 4D reconstruction and the McKinnon-Bates (MB) reconstruction algorithms. Both the 4D-VOI and the MB reconstructions suppress nearly all the streak artifacts compared with the standard 4D reconstruction, but the 4D-VOI has 3-8 times greater contrast-to-noise ratio than the MB reconstruction. In the dynamic chest phantom study, the 4D-VOI and the standard 4D reconstructions both resolved a moving sphere with an 18 mm displacement. The 4D-VOI reconstruction shows a motion blur of only 3 mm, whereas the MB reconstruction shows a motion blur of 13 mm

  5. From physical dose constraints to equivalent uniform dose constraints in inverse radiotherapy planning

    International Nuclear Information System (INIS)

    Thieke, Christian; Bortfeld, Thomas; Niemierko, Andrzej; Nill, Simeon

    2003-01-01

    Optimization algorithms in inverse radiotherapy planning need information about the desired dose distribution. Usually the planner defines physical dose constraints for each structure of the treatment plan, either in form of minimum and maximum doses or as dose-volume constraints. The concept of equivalent uniform dose (EUD) was designed to describe dose distributions with a higher clinical relevance. In this paper, we present a method to consider the EUD as an optimization constraint by using the method of projections onto convex sets (POCS). In each iteration of the optimization loop, for the actual dose distribution of an organ that violates an EUD constraint a new dose distribution is calculated that satisfies the EUD constraint, leading to voxel-based physical dose constraints. The new dose distribution is found by projecting the current one onto the convex set of all dose distributions fulfilling the EUD constraint. The algorithm is easy to integrate into existing inverse planning systems, and it allows the planner to choose between physical and EUD constraints separately for each structure. A clinical case of a head and neck tumor is optimized using three different sets of constraints: physical constraints for all structures, physical constraints for the target and EUD constraints for the organs at risk, and EUD constraints for all structures. The results show that the POCS method converges stable and given EUD constraints are reached closely

  6. String propagation in an exact four-dimensional black hole background

    International Nuclear Information System (INIS)

    Mahapatra, S.

    1997-01-01

    We study string propagation in an exact, stringy, four-dimensional dyonic black hole background. The exact solutions in terms of elliptic functions describing string configurations in the J=0 limit are obtained by solving the string equations of motion and constraints. By using the covariant formalism, we also investigate the propagation of physical perturbations along the string in the given curved background. copyright 1997 The American Physical Society

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

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Lowe, D.A.; Maldacena, J.M.

    1996-01-01

    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

  8. Four-dimensional Microscope-Integrated Optical Coherence Tomography to Visualize Suture Depth in Strabismus Surgery.

    Science.gov (United States)

    Pasricha, Neel D; Bhullar, Paramjit K; Shieh, Christine; Carrasco-Zevallos, Oscar M; Keller, Brenton; Izatt, Joseph A; Toth, Cynthia A; Freedman, Sharon F; Kuo, Anthony N

    2017-02-14

    The authors report the use of swept-source microscope-integrated optical coherence tomography (SS-MIOCT), capable of live four-dimensional (three-dimensional across time) intraoperative imaging, to directly visualize suture depth during lateral rectus resection. Key surgical steps visualized in this report included needle depth during partial and full-thickness muscle passes along with scleral passes. [J Pediatr Ophthalmol Strabismus. 2017;54:e1-e5.]. Copyright 2017, SLACK Incorporated.

  9. Haunted Kaluza universe with four-dimensional Lorentzian flat, Kerr, and Taub-NUT slices

    International Nuclear Information System (INIS)

    Ivanov, Rossen I.; Prodanov, Emil M.

    2005-01-01

    The duality between the original Kaluza's theory and Klein's subsequent modification is duality between slicing and threading decomposition of the five-dimensional spacetime. The field equations of the original Kaluza's theory lead to the interpretation of the four-dimensional Lorentzian Kerr and Taub-NUT solutions as resulting from static electric and magnetic charges and dipoles in the presence of ghost matter and constant dilaton, which models Newton's constant

  10. Feasibility of four-dimensional preoperative simulation for elbow debridement arthroplasty.

    Science.gov (United States)

    Yamamoto, Michiro; Murakami, Yukimi; Iwatsuki, Katsuyuki; Kurimoto, Shigeru; Hirata, Hitoshi

    2016-04-02

    Recent advances in imaging modalities have enabled three-dimensional preoperative simulation. A four-dimensional preoperative simulation system would be useful for debridement arthroplasty of primary degenerative elbow osteoarthritis because it would be able to detect the impingement lesions. We developed a four-dimensional simulation system by adding the anatomical axis to the three-dimensional computed tomography scan data of the affected arm in one position. Eleven patients with primary degenerative elbow osteoarthritis were included. A "two rings" method was used to calculate the flexion-extension axis of the elbow by converting the surface of the trochlea and capitellum into two rings. A four-dimensional simulation movie was created and showed the optimal range of motion and the impingement area requiring excision. To evaluate the reliability of the flexion-extension axis, interobserver and intraobserver reliabilities regarding the assessment of bony overlap volumes were calculated twice for each patient by two authors. Patients were treated by open or arthroscopic debridement arthroplasties. Pre- and postoperative examinations included elbow range of motion measurement, and completion of the patient-rated questionnaire Hand20, Japanese Orthopaedic Association-Japan Elbow Society Elbow Function Score, and the Mayo Elbow Performance Score. Measurement of the bony overlap volume showed an intraobserver intraclass correlation coefficient of 0.93 and 0.90, and an interobserver intraclass correlation coefficient of 0.94. The mean elbow flexion-extension arc significantly improved from 101° to 125°. The mean Hand20 score significantly improved from 52 to 22. The mean Japanese Orthopaedic Association-Japan Elbow Society Elbow Function Score significantly improved from 67 to 88. The mean Mayo Elbow Performance Score significantly improved from 71 to 91 at the final follow-up evaluation. We showed that four-dimensional, preoperative simulation can be generated by

  11. Nonperturbative construction of nonrenormalizable models of quantum field theory in four-dimensional space-time

    International Nuclear Information System (INIS)

    Raczka, R.

    1979-01-01

    Construction of non-cutoff Euclidean Green's functions for nonrenormalizable interactions Lsub(I)(phi)=lambda∫dσ(epsilon):expepsilonphi: in four-dimensional space-time is presented. It is shown that all axioms for the generating functional of E.G.F. are satisfied except perhaps the SO(4) invariance. It is shown that the singularities of E.G.F. for coinciding points are not worse than those of the free theory. (author)

  12. Intensity-modulated radiotherapy (IMRT) for carcinoma of the maxillary sinus: A comparison of IMRT planning systems

    International Nuclear Information System (INIS)

    Ahmed, Raef S.; Ove, Roger; Duan, Jun; Popple, Richard; Cobb, Glenn

    2006-01-01

    The treatment of maxillary sinus carcinoma with forward planning can be technically difficult when the neck also requires radiotherapy. This difficulty arises because of the need to spare the contralateral face while treating the bilateral neck. There is considerable potential for error in clinical setup and treatment delivery. We evaluated intensity-modulated radiotherapy (IMRT) as an improvement on forward planning, and compared several inverse planning IMRT platforms. A composite dose-volume histogram (DVH) was generated from a complex forward planned case. We compared the results with those generated by sliding window fixed field dynamic multileaf collimator (MLC) IMRT, using sets of coplanar beams. All setups included an anterior posterior (AP) beam, and 3-, 5-, 7-, and 9-field configurations were evaluated. The dose prescription and objective function priorities were invariant. We also evaluated 2 commercial tomotherapy IMRT delivery platforms. DVH results from all of the IMRT approaches compared favorably with the forward plan. Results for the various inverse planning approaches varied considerably across platforms, despite an attempt to prescribe the therapy similarly. The improvement seen with the addition of beams in the fixed beam sliding window case was modest. IMRT is an effective means of delivering radiotherapy reliably in the complex setting of maxillary sinus carcinoma with neck irradiation. Differences in objective function definition and optimization algorithms can lead to unexpected differences in the final dose distribution, and our evaluation suggests that these factors are more significant than the beam arrangement or number of beams

  13. Higher-order gravity in higher dimensions: geometrical origins of four-dimensional cosmology?

    Energy Technology Data Exchange (ETDEWEB)

    Troisi, Antonio [Universita degli Studi di Salerno, Dipartimento di Fisica ' ' E.R. Caianiello' ' , Salerno (Italy)

    2017-03-15

    Determining the cosmological field equations is still very much debated and led to a wide discussion around different theoretical proposals. A suitable conceptual scheme could be represented by gravity models that naturally generalize Einstein theory like higher-order gravity theories and higher-dimensional ones. Both of these two different approaches allow one to define, at the effective level, Einstein field equations equipped with source-like energy-momentum tensors of geometrical origin. In this paper, the possibility is discussed to develop a five-dimensional fourth-order gravity model whose lower-dimensional reduction could provide an interpretation of cosmological four-dimensional matter-energy components. We describe the basic concepts of the model, the complete field equations formalism and the 5-D to 4-D reduction procedure. Five-dimensional f(R) field equations turn out to be equivalent, on the four-dimensional hypersurfaces orthogonal to the extra coordinate, to an Einstein-like cosmological model with three matter-energy tensors related with higher derivative and higher-dimensional counter-terms. By considering the gravity model with f(R) = f{sub 0}R{sup n} the possibility is investigated to obtain five-dimensional power law solutions. The effective four-dimensional picture and the behaviour of the geometrically induced sources are finally outlined in correspondence to simple cases of such higher-dimensional solutions. (orig.)

  14. Tumor and normal structures volume localization and quantitation in 3D radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Anselmi, R.; Andreucci, L.

    1995-01-01

    Improvements in imaging technology have significantly enhanced the ability of the radiation oncologist to stage and to evaluate the response of tumor during and after treatment. Over the last few year, in fact, computed tomography (CT), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), single photon emission computed tomography (SPECT) imaging radiolabelled monoclonal tumor antibodies have allowed tumor definition and evaluation. Concerning the above mentioned techniques accurate methods for the integration of morphological (CT, MRI) and functional (PET, SPECT, MRS) information can be very useful for volumes definition. In fact three-dimensional treatment planning depends heavily on volume displays and calculation based on volumes to convey information to the radiation oncologist, physicist and dosimetrist. The accuracy and reproducibility of the methods for creating these volumes are fundamental limitations of current treatment planning systems. Slice by slice manual contouring, which is extremely labor-intensive, and automatic edge detection, which has a high failure rate and requires human intervention are representative of the current standard of practice. The aim of our work is both to develop methods of image data integration and automatic segmentation, and to make the treatment planning system able to combine these multiple information in unified data set in order to get a better tumor volume definition and dose distribution calculation. Then the possibility of using morphological and functional images and other information coming from MR spectroscopy and electronic or confocal microscopy can allow the development into the treatment planning system of biological calculation models for evaluating tumor and normal tissue control probabilities (TCP, NTCP). The definitive use of these models into the 3-D treatment plannings will offer a considerable improvement in the biological efficacy of radiotherapy and it will constitute the object

  15. SU-F-T-80: A Mobile Application for Intra-Operative Electron Radiotherapy Treatment Planning

    International Nuclear Information System (INIS)

    Williams, C; Crowley, E; Wolfgang, J

    2016-01-01

    Purpose: Intraoperative electron radiotherapy (IORT) poses a unique set of challenges for treatment planning. Planning must be performed in a busy operating room environment over a short timeframe often with little advance knowledge of the treatment depth or applicator size. Furthermore, IORT accelerators can have a large number of possible applicators, requiring extensive databooks that must be searched for the appropriate dosimetric parameters. The goal of this work is to develop a software tool to assist in the planning process that is suited to the challenges faced in the IORT environment. Methods: We developed a mobile application using HTML5 and Javascript that can be deployed to tablet devices suitable for use in the operating room. The user selects the desired treatment parameters cone diameter, bevel angle, and energy (a total of 141 datasets) and desired bolus. The application generates an interactive display that allows the user to dynamically select points on the depth-dose curve and to visualize the shape of the corresponding isodose contours. The user can indicate a prescription isodose line or depth. The software performs a monitor unit calculation and generates a PDF report. Results: We present our application, which is now used routinely in our IORT practice. It has been employed successfully in over 23 cases. The interactivity of the isodose distributions was found to be of particular use to physicians who are less-frequent IORT users, as well as for the education of residents and trainees. Conclusion: This software has served as a useful tool in IORT planning, and demonstrates the need for treatment planning tools that are designed for the specialized challenges encountered in IORT. This software is the subject of a license agreement with the IntraOp Medical Corporation. This software is the subject of a license agreement between Massachusetts General Hospital / Partners Healthcare and the IntraOp Medical Corporation. CLW is consulting on

  16. SU-F-T-80: A Mobile Application for Intra-Operative Electron Radiotherapy Treatment Planning

    Energy Technology Data Exchange (ETDEWEB)

    Williams, C [Brigham and Women’s Hospital & Dana Farber Cancer Institute, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Crowley, E; Wolfgang, J [Harvard Medical School, Boston, MA (United States); Massachusetts General Hospital, Boston, MA (United States)

    2016-06-15

    Purpose: Intraoperative electron radiotherapy (IORT) poses a unique set of challenges for treatment planning. Planning must be performed in a busy operating room environment over a short timeframe often with little advance knowledge of the treatment depth or applicator size. Furthermore, IORT accelerators can have a large number of possible applicators, requiring extensive databooks that must be searched for the appropriate dosimetric parameters. The goal of this work is to develop a software tool to assist in the planning process that is suited to the challenges faced in the IORT environment. Methods: We developed a mobile application using HTML5 and Javascript that can be deployed to tablet devices suitable for use in the operating room. The user selects the desired treatment parameters cone diameter, bevel angle, and energy (a total of 141 datasets) and desired bolus. The application generates an interactive display that allows the user to dynamically select points on the depth-dose curve and to visualize the shape of the corresponding isodose contours. The user can indicate a prescription isodose line or depth. The software performs a monitor unit calculation and generates a PDF report. Results: We present our application, which is now used routinely in our IORT practice. It has been employed successfully in over 23 cases. The interactivity of the isodose distributions was found to be of particular use to physicians who are less-frequent IORT users, as well as for the education of residents and trainees. Conclusion: This software has served as a useful tool in IORT planning, and demonstrates the need for treatment planning tools that are designed for the specialized challenges encountered in IORT. This software is the subject of a license agreement with the IntraOp Medical Corporation. This software is the subject of a license agreement between Massachusetts General Hospital / Partners Healthcare and the IntraOp Medical Corporation. CLW is consulting on

  17. Technical Note: MRI only prostate radiotherapy planning using the statistical decomposition algorithm

    International Nuclear Information System (INIS)

    Siversson, Carl; Nordström, Fredrik; Nilsson, Terese; Nyholm, Tufve; Jonsson, Joakim; Gunnlaugsson, Adalsteinn; Olsson, Lars E.

    2015-01-01

    Purpose: In order to enable a magnetic resonance imaging (MRI) only workflow in radiotherapy treatment planning, methods are required for generating Hounsfield unit (HU) maps (i.e., synthetic computed tomography, sCT) for dose calculations, directly from MRI. The Statistical Decomposition Algorithm (SDA) is a method for automatically generating sCT images from a single MR image volume, based on automatic tissue classification in combination with a model trained using a multimodal template material. This study compares dose calculations between sCT generated by the SDA and conventional CT in the male pelvic region. Methods: The study comprised ten prostate cancer patients, for whom a 3D T2 weighted MRI and a conventional planning CT were acquired. For each patient, sCT images were generated from the acquired MRI using the SDA. In order to decouple the effect of variations in patient geometry between imaging modalities from the effect of uncertainties in the SDA, the conventional CT was nonrigidly registered to the MRI to assure that their geometries were well aligned. For each patient, a volumetric modulated arc therapy plan was created for the registered CT (rCT) and recalculated for both the sCT and the conventional CT. The results were evaluated using several methods, including mean average error (MAE), a set of dose-volume histogram parameters, and a restrictive gamma criterion (2% local dose/1 mm). Results: The MAE within the body contour was 36.5 ± 4.1 (1 s.d.) HU between sCT and rCT. Average mean absorbed dose difference to target was 0.0% ± 0.2% (1 s.d.) between sCT and rCT, whereas it was −0.3% ± 0.3% (1 s.d.) between CT and rCT. The average gamma pass rate was 99.9% for sCT vs rCT, whereas it was 90.3% for CT vs rCT. Conclusions: The SDA enables a highly accurate MRI only workflow in prostate radiotherapy planning. The dosimetric uncertainties originating from the SDA appear negligible and are notably lower than the uncertainties

  18. An interactive beam-weight optimization tool for three-dimensional radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Burba, S.; Gardey, K.; Nadobny, J.; Stalling, D.; Seebass, M.; Beier, J.; Wust, P.; Budach, V.; Felix, R.

    1997-01-01

    Purpose: A computer software tool has been developed to aid the treatment planner in selecting beam weights for three-dimensional radiotherapy treatment planning. An approach to plan optimization has been made that is based on the use of an iterative feasibility search algorithm combined with a quadratic convergence method that seeks a set of beam weights which satisfies all the dose constraints set by the planner. Materials and Methods: A FORTRAN module for dose calculation for radiotherapy (a VOXELPLAN modification) has been integrated into an object-oriented Silicon Graphics TM platform in an IRIS Inventor environment on basis of the OpenGL which up to now has been exclusively used for the calculation of E-field distributions in hyperthermia (HyperPlan TM ). After the successful calculation and representation of the dose distribution in the Silicon Graphics TM platform, an algorithm involving the minimization method according to the principle of quadratic convergence was developed for optimizing beam weights of a number of pre-calculated fields. The verification of the algorithms for dose calculation and dose optimization has been realized by use of a standardized interface to the program VIRTUOS as well as by the collapsed cone algorithm implemented in the commercial treatment planning system Helax TMS TM . Results: The search algorithm allows the planner to incorporate relative importance weightings to target volumes and anatomical structures, specifying, for example, that a dose constraint to the spinal cord is much more crucial to the overall evaluation of a treatment plan than a dose constraint to otherwise uninvolved soft tissue. In most cases the applied minimization method according to the model of Davidon-Fletcher-Powell showed ultimate fast convergence for a general function f(x) with continuous second derivatives and fast convergence for a positive definite quadratic function. In other cases, however, the absence of an acceptable solution may indicate

  19. Impact of collimator leaf width on stereotactic radiosurgery and 3D conformal radiotherapy treatment plans

    International Nuclear Information System (INIS)

    Kubo, H. Dale; Wilder, Richard B.; Pappas, Conrad T.E.

    1999-01-01

    Purpose: The authors undertook a study to analyze the impact of collimator leaf width on stereotactic radiosurgery and 3D conformal radiotherapy treatment plans. Methods and Materials: Twelve cases involving primary brain tumors, metastases, or arteriovenous malformations that had been planned with BrainLAB's conventional circular collimator-based radiosurgery system were re-planned using a β-version of BrainLAB's treatment planning software that is compatible with MRC Systems' and BrainLAB's micro-multileaf collimators. These collimators have a minimum leaf width of 1.7 mm and 3.0 mm, respectively, at isocenter. The clinical target volumes ranged from 2.7-26.1 cc and the number of static fields ranged from 3-5. In addition, for 4 prostate cancer cases, 2 separate clinical target volumes were planned using MRC Systems' and BrainLAB's micro-multileaf collimators and Varian's multileaf collimator: the smaller clinical target volume consisted of the prostate gland and the larger clinical target volume consisted of the prostate and seminal vesicles. For the prostate cancer cases, treatment plans were generated using either 6 or 7 static fields. A 'PITV ratio', which the Radiation Therapy Oncology Group defines as the volume encompassed by the prescription isodose surface divided by the clinical target volume, was used as a measure of the quality of treatment plans (a PITV ratio of 1.0-2.0 is desirable). Bladder and rectal volumes encompassed by the prescription isodose surface, isodose distributions and dose volume histograms were also analyzed for the prostate cancer patients. Results: In 75% of the cases treated with radiosurgery, a PITV ratio between 1.0-2.0 could be achieved using a micro-multileaf collimator with a leaf width of 1.7-3.0 mm at isocenter and 3-5 static fields. When the clinical target volume consisted of the prostate gland, the micro-multileaf collimator with a minimum leaf width of 3.0 mm allowed one to decrease the median volume of bladder and

  20. The Quality of Curative-intent Radiotherapy for Non-small Cell Lung Cancer in the UK.

    Science.gov (United States)

    McAleese, J; Baluch, S; Drinkwater, K

    2015-09-01

    Lung cancer is the leading cause of cancer-related death in the UK. The quality of curative-intent radiotherapy is associated with better outcomes. National quality standards from the National Institute for Health and Care Excellence (NICE) on patient work-up and treatment selection were used, with guidance from the Royal College of Radiologists on the technical delivery of radiotherapy, to assess the quality of curative-intent non-small cell lung cancer radiotherapy and to describe current UK practice. Radiotherapy departments completed one questionnaire for each patient started on curative-intent radiotherapy for 8 weeks in 2013. Eighty-two per cent of centres returned a total of 317 proformas. Patient selection with positron emission tomography/computed tomography, performance status and Forced Expiratory Volume in 1 second (FEV1) was usually undertaken. Fifty-six per cent had pathological confirmation of mediastinal lymph nodes and 22% staging brain scans; 20% were treated with concurrent chemoradiation, 12% with Stereotactic Ablative Radiotherapy (SABR) and 8% with Continuous Hyperfractionated Accelerated Radiotherapy (CHART). Sixty-three per cent of patients received 55 Gy/20 fractions. Although respiratory compensation was routinely undertaken, only 33% used four-dimensional computed tomography. Seventy per cent of patients were verified with cone beam computed tomography. There was consistency of practice in dosimetric constraints for organs at risk and follow-up. This audit has described current UK practice. The latest recommendations for patient selection with pathological confirmation of mediastinal lymph nodes, brain staging and respiratory function testing are not universally followed. Although there is evidence of increasing use of newer techniques such as four-dimensional computed tomography and cone beam image-guided radiotherapy, there is still variability in access. Efforts should be made to improve access to modern technologies and quality

  1. Clinical impact of FDG-PET/CT in the planning of radiotherapy for early-stage Hodgkin lymphoma

    DEFF Research Database (Denmark)

    Hutchings, Martin; Loft, Annika; Hansen, Mads

    2007-01-01

    BACKGROUND: Early-stage Hodgkin lymphoma (HL) has excellent survival rates but carries a high risk of late treatment-related adverse effects. Modern, individualised therapeutic strategies require an accurate determination of the extent of the disease. This study investigated the potential impact...... of 2-[18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computerised tomogrpahy (FDG-PET/CT) in the planning of involved field radiotherapy (IFRT). PATIENTS AND METHODS: Thirty patients received staging FDG-PET/CT before therapy, and IFRT after a short course of ABVD (adriamycin, bleomycin......, vinblastine, dacarbazine) chemotherapy. IFRT planning was performed using only the CT data from the FDG-PET/CT scan. Later, the IFRT planning was performed anew using the FDG-PET/CT data as basis for contouring. RESULTS: In 20 out of 30 patients, the radiotherapy (RT) course was unaffected by the addition...

  2. Dosimetric impact of image artifact from a wide-bore CT scanner in radiotherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Vincent; Podgorsak, Matthew B.; Tran, Tuan-Anh; Malhotra, Harish K.; Wang, Iris Z. [Department of Radiation Medicine, Roswell Park Cancer Institute, Buffalo, New York 14263 (United States); Department of Radiation Medicine, Roswell Park Cancer Institute, Buffalo, New York 14263 and Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214 (United States); Department of Radiation Medicine, Roswell Park Cancer Institute, Buffalo, New York 14263 (United States); Department of Radiation Medicine, Roswell Park Cancer Institute, Buffalo, New York 14263 and Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214 (United States)

    2011-07-15

    Purpose: Traditional computed tomography (CT) units provide a maximum scan field-of-view (sFOV) diameter of 50 cm and a limited bore size, which cannot accommodate a large patient habitus or an extended simulation setup in radiation therapy (RT). Wide-bore CT scanners with increased bore size were developed to address these needs. Some scanners have the capacity to reconstruct the CT images at an extended FOV (eFOV), through data interpolation or extrapolation, using projection data acquired with a conventional sFOV. Objects that extend past the sFOV for eFOV reconstruction may generate image artifacts resulting from truncated projection data; this may distort CT numbers and structure contours in the region beyond the sFOV. The purpose of this study was to evaluate the dosimetric impact of image artifacts from eFOV reconstruction with a wide-bore CT scanner in radiotherapy (RT) treatment planning. Methods: Testing phantoms (i.e., a mini CT phantom with equivalent tissue inserts, a set of CT normal phantoms and anthropomorphic phantoms of the thorax and the pelvis) were used to evaluate eFOV artifacts. Reference baseline images of these phantoms were acquired with the phantom centrally positioned within the sFOV. For comparison, the phantoms were then shifted laterally and scanned partially outside the sFOV, but still within the eFOV. Treatment plans were generated for the thoracic and pelvic anthropomorphic phantoms utilizing the Eclipse treatment planning system (TPS) to study the potential effects of eFOV artifacts on dose calculations. All dose calculations of baseline and test treatment plans were carried out using the same MU. Results: Results show that both body contour and CT numbers are altered by image artifacts in eFOV reconstruction. CT number distortions of up to -356 HU for bone tissue and up to 323 HU for lung tissue were observed in the mini CT phantom. Results from the large body normal phantom, which is close to a clinical patient size, show

  3. SU-F-T-358: Is Auto-Planning Useful for Volumetric-Modulated Arc Therapy Planning in Rectal Cancer Radiotherapy?

    International Nuclear Information System (INIS)

    Li, K; Chang, X; Wang, J; Hu, P; Hu, W

    2016-01-01

    Purpose: To evaluate whether Auto-Planning based volumetric-modulated radiotherapy (auto-VMAT) can reduce manual interaction time during treatment planning and improve plan quality for rectal cancer radiotherapy. Methods: Ten rectal cancer patients (stage II and III) after radical resection using Dixon surgery were enrolled. All patients were treated with VMAT technique. The manual VMAT plans (man-VMAT) were designed in the Pinnacle treatment planning system (Version 9.10) following the standard treatment planning procedure developed in our department. Clinical plans were manually designed by our experienced dosimetrists. Additionally, an auto-VMAT plan was created for each patient using Auto-Planning module. However, manual interaction was still applied to meet the clinical requirements. The treatment planning time and plan quality surrogated by the DVH parameters were compared between manual and automated plans. Results: The total planning time and manual interaction time were 50.38 and 4.47 min for the auto-VMAT and 36.81 and 16.94 min for the man-VMAT (t=60.14,−23.86; p=0.000, 0.000). In terms of plan quality, both plans meet the clinical requirements. The PTV homogeneity index (HI) and conformity index (CI) were 0.054 and 0.822 for the auto-VMAT and 0.059 and 0.815 for the man-VMAT (t=−1.72, 0.36;p=0.119,0.730).Compared to the man-VMAT, the auto-VMAT showed reduction of 11.9% and 0.7% in V40 and V50 of the bladder, respectively.The V30 and D mean were reduced by 14.0% and 5.1Gy in the left femur and 12.2% and 3.8Gy in the right femur. Conclusion: The Auto-Planning based VMAT plans not only shows similar or superior plan quality to the manual ones in the rectal cancer radiotherapy, but also improve the planning efficiency significantly. However, manual interactions are still required to achieve a clinically acceptable plan based on our experiences.

  4. SU-F-T-358: Is Auto-Planning Useful for Volumetric-Modulated Arc Therapy Planning in Rectal Cancer Radiotherapy?

    Energy Technology Data Exchange (ETDEWEB)

    Li, K; Chang, X; Wang, J; Hu, P; Hu, W [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China)

    2016-06-15

    Purpose: To evaluate whether Auto-Planning based volumetric-modulated radiotherapy (auto-VMAT) can reduce manual interaction time during treatment planning and improve plan quality for rectal cancer radiotherapy. Methods: Ten rectal cancer patients (stage II and III) after radical resection using Dixon surgery were enrolled. All patients were treated with VMAT technique. The manual VMAT plans (man-VMAT) were designed in the Pinnacle treatment planning system (Version 9.10) following the standard treatment planning procedure developed in our department. Clinical plans were manually designed by our experienced dosimetrists. Additionally, an auto-VMAT plan was created for each patient using Auto-Planning module. However, manual interaction was still applied to meet the clinical requirements. The treatment planning time and plan quality surrogated by the DVH parameters were compared between manual and automated plans. Results: The total planning time and manual interaction time were 50.38 and 4.47 min for the auto-VMAT and 36.81 and 16.94 min for the man-VMAT (t=60.14,−23.86; p=0.000, 0.000). In terms of plan quality, both plans meet the clinical requirements. The PTV homogeneity index (HI) and conformity index (CI) were 0.054 and 0.822 for the auto-VMAT and 0.059 and 0.815 for the man-VMAT (t=−1.72, 0.36;p=0.119,0.730).Compared to the man-VMAT, the auto-VMAT showed reduction of 11.9% and 0.7% in V40 and V50 of the bladder, respectively.The V30 and D mean were reduced by 14.0% and 5.1Gy in the left femur and 12.2% and 3.8Gy in the right femur. Conclusion: The Auto-Planning based VMAT plans not only shows similar or superior plan quality to the manual ones in the rectal cancer radiotherapy, but also improve the planning efficiency significantly. However, manual interactions are still required to achieve a clinically acceptable plan based on our experiences.

  5. Megavoltage conebeam CT cine as final verification of treatment plan in lung stereotactic body radiotherapy.

    Science.gov (United States)

    Kudithipudi, Vijay; Gayou, Olivier; Colonias, Athanasios

    2016-06-01

    To analyse the clinical impact of megavoltage conebeam computed tomography (MV-CBCT) cine on internal target volume (ITV) coverage in lung stereotactic body radiotherapy (SBRT). One hundred and six patients received lung SBRT. All underwent 4D computed tomography simulation followed by treatment via image guided 3D conformal or intensity modulated radiation. Prior to SBRT, all patients underwent MV-CBCT cine, in which raw projections are displayed as beam's-eye-view fluoroscopic series with the planning target volume (PTV) projected onto each image, enabling verification of tumour motion relative to the PTV and assessment of adequacy of treatment margin. Megavoltage conebeam computed tomography cine was completed 1-2 days prior to SBRT. Four patients (3.8%) had insufficient ITV coverage inferiorly at cine review. All four plans were changed by adding 5 mm on the PTV margin inferiorly. The mean change in PTV volumes was 3.9 cubic centimetres (cc) (range 1.85-6.32 cc). Repeat cine was performed after plan modification to ensure adequate PTV coverage in the modified plans. PTV margin was adequate in the majority of patients with this technique. MV-CBCT cine did show insufficient coverage in a small subset of patients. Insufficient PTV margins may be a function of 4D CT simulation inadequacies or deficiencies in visualizing the ITV inferior border in the full-inhale phase. MV-CBCT cine is a valuable tool for final verification of PTV margins. © 2016 The Royal Australian and New Zealand College of Radiologists.

  6. Enable dosimetric of the Stereotactic Body Frame from Elekta in treatment planning systems for Radiotherapy

    International Nuclear Information System (INIS)

    Gonzalez Perez, Y.; Caballero Pinelo, R.; Alfonso Laguardia, R.

    2015-01-01

    The purpose of this study is to evaluate the commissioning of a stereotactic body frame (SBF ® , Elekta) professional treatment planning systems (TPS) model Elekta's PrecisePlan ® and ERGO++®, for highly foxused delivery of megavoltage photon beams intended for treating tumors located in the thorax and abdominal region. For this purpose we applicated a dedicate stereotactic body frame (SBF ® , Elekta) intended for high precision radiotherapy in extra-cranial located tumors was studied. Issues associated with their implementation in the TPSs were evaluated comparing the dose calculations in two studies of CT under different conditions. an anthropomorphic thorax phantom, model CIRS Thorax IMRT ® , was used in designing several test cases. Ion chamber measurement was permormed in selected points in the phantom, for comparison purposes with dose calculated by the treatment planning systems. The commissioning of the stereotactic body frame (SBF ® , Elekta) and the stereotactic localization was verified, including the dose calculation verification in presence the SBF. The attenuation factors measured for the SBF were obtained and corrected in the TPS PrecisePlan ® , the biggest discrepancies obtained were ∼5% for the oblique sectors (inferior corners), because the minimum permissible value for the software is 0.95 while the real value measured was 0.898. It was studied the SBF, their components and their interference in depth with the photon beams and their implementation in the TPS. The introduction of the correction factors demonstrated to be effective to reduce the eventual errors of dose calculation in the TPS . (Author)

  7. A class solution for volumetric-modulated arc therapy planning in postprostatectomy radiotherapy

    International Nuclear Information System (INIS)

    Forde, Elizabeth; Bromley, Regina; Kneebone, Andrew; Eade, Thomas

    2014-01-01

    This study is aimed to test a postprostatectomy volumetric-modulated arc therapy (VMAT) planning class solution. The solution applies to both the progressive resolution optimizer algorithm version 2 (PRO 2) and the algorithm version 3 (PRO 3), addressing the effect of an upgraded algorithm. A total of 10 radical postprostatectomy patients received 68 Gy to 95% of the planning target volume (PTV), which was planned using VMAT. Each case followed a set of planning instructions; including contouring, field setup, and predetermined optimization parameters. Each case was run through both algorithms only once, with no user interaction. Results were averaged and compared against Radiation Therapy Oncology Group (RTOG) 0534 end points. In addition, the clinical target volume (CTV) D 100 , PTV D 99 , and PTV mean doses were recorded, along with conformity indices (CIs) (95% and 98%) and the homogeneity index. All cases satisfied PTV D 95 of 68 Gy and a maximum dose < 74.8 Gy. The average result for the PTV D 99 was 64.1 Gy for PRO 2 and 62.1 Gy for PRO 3. The average PTV mean dose for PRO 2 was 71.4 Gy and 71.5 Gy for PRO 3. The CTV D 100 average dose was 67.7 and 68.0 Gy for PRO 2 and PRO 3, respectively. The mean homogeneity index for both algorithms was 0.08. The average 95% CI was 1.17 for PRO 2 and 1.19 for PRO 3. For 98%, the average results were 1.08 and 1.12 for PRO 2 and PRO 3, respectively. All cases for each algorithm met the RTOG organs at risk dose constraints. A successful class solution has been established for prostate bed VMAT radiotherapy regardless of the algorithm used

  8. A class solution for volumetric-modulated arc therapy planning in postprostatectomy radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Forde, Elizabeth, E-mail: eforde@tcd.ie [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Bromley, Regina [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Institute of Medical Physics, School of Physics, University of Sydney, New South Wales (Australia); Kneebone, Andrew; Eade, Thomas [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Northern Clinical School, University of Sydney, New South Wales (Australia)

    2014-10-01

    This study is aimed to test a postprostatectomy volumetric-modulated arc therapy (VMAT) planning class solution. The solution applies to both the progressive resolution optimizer algorithm version 2 (PRO 2) and the algorithm version 3 (PRO 3), addressing the effect of an upgraded algorithm. A total of 10 radical postprostatectomy patients received 68 Gy to 95% of the planning target volume (PTV), which was planned using VMAT. Each case followed a set of planning instructions; including contouring, field setup, and predetermined optimization parameters. Each case was run through both algorithms only once, with no user interaction. Results were averaged and compared against Radiation Therapy Oncology Group (RTOG) 0534 end points. In addition, the clinical target volume (CTV) D{sub 100}, PTV D{sub 99}, and PTV mean doses were recorded, along with conformity indices (CIs) (95% and 98%) and the homogeneity index. All cases satisfied PTV D{sub 95} of 68 Gy and a maximum dose < 74.8 Gy. The average result for the PTV D{sub 99} was 64.1 Gy for PRO 2 and 62.1 Gy for PRO 3. The average PTV mean dose for PRO 2 was 71.4 Gy and 71.5 Gy for PRO 3. The CTV D{sub 100} average dose was 67.7 and 68.0 Gy for PRO 2 and PRO 3, respectively. The mean homogeneity index for both algorithms was 0.08. The average 95% CI was 1.17 for PRO 2 and 1.19 for PRO 3. For 98%, the average results were 1.08 and 1.12 for PRO 2 and PRO 3, respectively. All cases for each algorithm met the RTOG organs at risk dose constraints. A successful class solution has been established for prostate bed VMAT radiotherapy regardless of the algorithm used.

  9. Knowledge-light adaptation approaches in case-based reasoning for radiotherapy treatment planning.

    Science.gov (United States)

    Petrovic, Sanja; Khussainova, Gulmira; Jagannathan, Rupa

    2016-03-01

    Radiotherapy treatment planning aims at delivering a sufficient radiation dose to cancerous tumour cells while sparing healthy organs in the tumour-surrounding area. It is a time-consuming trial-and-error process that requires the expertise of a group of medical experts including oncologists and medical physicists and can take from 2 to 3h to a few days. Our objective is to improve the performance of our previously built case-based reasoning (CBR) system for brain tumour radiotherapy treatment planning. In this system, a treatment plan for a new patient is retrieved from a case base containing patient cases treated in the past and their treatment plans. However, this system does not perform any adaptation, which is needed to account for any difference between the new and retrieved cases. Generally, the adaptation phase is considered to be intrinsically knowledge-intensive and domain-dependent. Therefore, an adaptation often requires a large amount of domain-specific knowledge, which can be difficult to acquire and often is not readily available. In this study, we investigate approaches to adaptation that do not require much domain knowledge, referred to as knowledge-light adaptation. We developed two adaptation approaches: adaptation based on machine-learning tools and adaptation-guided retrieval. They were used to adapt the beam number and beam angles suggested in the retrieved case. Two machine-learning tools, neural networks and naive Bayes classifier, were used in the adaptation to learn how the difference in attribute values between the retrieved and new cases affects the output of these two cases. The adaptation-guided retrieval takes into consideration not only the similarity between the new and retrieved cases, but also how to adapt the retrieved case. The research was carried out in collaboration with medical physicists at the Nottingham University Hospitals NHS Trust, City Hospital Campus, UK. All experiments were performed using real-world brain cancer

  10. New customized patient repositioning system for use in three dimensional (3D) treatment planning and radiotherapy

    International Nuclear Information System (INIS)

    Kitahara, Toshihiro; Shirato, Hiroki; Nishioka, Takeshi; Nishiyama, Noriaki; Yamaguchi, Megumi; Watanabe, Yoshiharu; Takekawa, Naomitu; Miyasaka, Kazuo

    1997-01-01

    Purpose/Objective: To develop a safe and easy method for customized patient repositioning and immobilization prior to 3-D treatment planning and during precise radiotherapy. Materials and methods: The new material consists of impression material, and covering material to fix and hold the impression. The impression material is composed of numerous effervescent polystyrene beads (3.1 mm in diameter) coated by polymerizing substance, urethane prepolymer. When being wet, the material beads adhere to each other due to polymelization, and it is hardened in 5 to 10 minutes. Within one hour the mold is sufficiently dry to be used for treatment planning utilizing computed tomography(CT). The physical characteristics of the material, the subjective comfort of the patient, the reduction in time required for repositioning in the treatment of the head and neck tumors, and the reduction in patient movement in the treatment of the breast cancers were investigated. Results: During the hardening stage, the maximum temperature of the material was 33 deg. C. Non-toxic CO 2 gas was produced and evaporated from the covering fabric. The mold, with a density of 0.095, was strong enough to endure compression, flexure, and scratching. In the healthy volunteers, no sensitivity to the skin was observed after 12 hours' attachment to the skin. The CT number of the material was less than minus 800, and no build-up effect was demonstrated in megavoltage photon therapy. Various molds were made and used as neck rest adjunctive to thermoplastic face mask, whole body cast, and arm rest (Figure). A questionnaire survey administered to 59 patients with brain, head and neck tumors, and to 18 patients with breast cancers, revealed that subjective comfort was markedly improved (90.9%) of improved (9.1%) by virtue of the new material. In the treatment of head and neck tumors, the mean time and SD for repositioning were 61.1 ± 13.6 seconds with the ready-made neck-rest and 49.4 ± 8.4 seconds with the

  11. Medical images fusion for application in treatment planning systems in radiotherapy

    International Nuclear Information System (INIS)

    Ros, Renato Assenci

    2006-01-01

    Software for medical images fusion was developed for utilization in CAT3D radiotherapy and MNPS radiosurgery treatment planning systems. A mutual information maximization methodology was used to make the image registration of different modalities by measure of the statistical dependence between the voxels pairs. The alignment by references points makes an initial approximation to the non linear optimization process by downhill simplex method for estimation of the joint histogram. The coordinates transformation function use a trilinear interpolation and search for the global maximum value in a 6 dimensional space, with 3 degree of freedom for translation and 3 degree of freedom for rotation, by making use of the rigid body model. This method was evaluated with CT, MR and PET images from Vanderbilt University database to verify its accuracy by comparison of transformation coordinates of each images fusion with gold-standard values. The median of images alignment error values was 1.6 mm for CT-MR fusion and 3.5 mm for PET-MR fusion, with gold-standard accuracy estimated as 0.4 mm for CT-MR fusion and 1.7 mm for PET-MR fusion. The maximum error values were 5.3 mm for CT-MR fusion and 7.4 mm for PET-MR fusion, and 99.1% of alignment errors were images subvoxels values. The mean computing time was 24 s. The software was successfully finished and implemented in 59 radiotherapy routine services, of which 42 are in Brazil and 17 are in Latin America. This method does not have limitation about different resolutions from images, pixels sizes and slice thickness. Besides, the alignment may be accomplished by axial, coronal or sagittal images. (author)

  12. Improving oncoplastic breast tumor bed localization for radiotherapy planning using image registration algorithms

    Science.gov (United States)

    Wodzinski, Marek; Skalski, Andrzej; Ciepiela, Izabela; Kuszewski, Tomasz; Kedzierawski, Piotr; Gajda, Janusz

    2018-02-01

    Knowledge about tumor bed localization and its shape analysis is a crucial factor for preventing irradiation of healthy tissues during supportive radiotherapy and as a result, cancer recurrence. The localization process is especially hard for tumors placed nearby soft tissues, which undergo complex, nonrigid deformations. Among them, breast cancer can be considered as the most representative example. A natural approach to improving tumor bed localization is the use of image registration algorithms. However, this involves two unusual aspects which are not common in typical medical image registration: the real deformation field is discontinuous, and there is no direct correspondence between the cancer and its bed in the source and the target 3D images respectively. The tumor no longer exists during radiotherapy planning. Therefore, a traditional evaluation approach based on known, smooth deformations and target registration error are not directly applicable. In this work, we propose alternative artificial deformations which model the tumor bed creation process. We perform a comprehensive evaluation of the most commonly used deformable registration algorithms: B-Splines free form deformations (B-Splines FFD), different variants of the Demons and TV-L1 optical flow. The evaluation procedure includes quantitative assessment of the dedicated artificial deformations, target registration error calculation, 3D contour propagation and medical experts visual judgment. The results demonstrate that the currently, practically applied image registration (rigid registration and B-Splines FFD) are not able to correctly reconstruct discontinuous deformation fields. We show that the symmetric Demons provide the most accurate soft tissues alignment in terms of the ability to reconstruct the deformation field, target registration error and relative tumor volume change, while B-Splines FFD and TV-L1 optical flow are not an appropriate choice for the breast tumor bed localization problem

  13. Comparison of two dimensional and three dimensional radiotherapy treatment planning in locally advanced non-small cell lung cancer treated with continuous hyperfractionated accelerated radiotherapy weekend less

    International Nuclear Information System (INIS)

    Wilson, Elena M.; Joy Williams, Frances; Ethan Lyn, Basil; Aird, Edwin G.A.

    2005-01-01

    Background and purpose: Patients with inoperable non-small cell lung cancer being treated with continuous hyperfractionated accelerated radiotherapy weekend less (CHARTWEL) were planned and treated with a three dimensional (3D) conformal protocol and comparison made with two dimensional (2D) planning, as used previously, to compare past practice and methods. Patients and methods: Twenty-four patients were planned initially using 3D and then replanned using a 2D system. The 2D plans were transferred onto the 3D system and recalculated. Dose volume histograms could then be constructed of planning target volumes for phases 1 and 2 (PTV 1 and 2, respectively), lung and spinal cord for the 2D plans and compared with the 3D plans. Results: There was a significantly lower absolute dose to the isocentre with 2D compared to 3D planning with dose reductions of 3.9% for phase 1, 4.4% for phase 2 and 4.7% for those treated with a single phase. Maximum dose to spinal cord was greater in 17 of the 24 2D plans with a median dose reduction of 0.82 Gy for 3D (P=0.04). The percentage volume of whole lung receiving ≥20 Gy (V 20 ) was greater in 16 of the 24 2D plans with a median reduction in V 20 of 2.4% for 3D (P=0.03). Conclusions: A lower dose to tumour was obtained using 2D planning due to the method of dose calculation and spinal cord and lung doses were significantly higher

  14. Impact of the accuracy of automatic tumour functional volume delineation on radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Le Maitre, Amandine; Hatt, Mathieu; Pradier, Olivier; Cheze-le Rest, Catherine; Visvikis, Dimitris

    2012-01-01

    Over the past few years several automatic and semi-automatic PET segmentation methods for target volume definition in radiotherapy have been proposed. The objective of this study is to compare different methods in terms of dosimetry. For such a comparison, a gold standard is needed. For this purpose, realistic GATE-simulated PET images were used. Three lung cases and three H and N cases were designed with various shapes, contrasts and heterogeneities. Four different segmentation approaches were compared: fixed and adaptive thresholds, a fuzzy C-mean and the fuzzy locally adaptive Bayesian method. For each of these target volumes, an IMRT treatment plan was defined. The different algorithms and resulting plans were compared in terms of segmentation errors and ground-truth volume coverage using different metrics (V 95 , D 95 , homogeneity index and conformity index). The major differences between the threshold-based methods and automatic methods occurred in the most heterogeneous cases. Within the two groups, the major differences occurred for low contrast cases. For homogeneous cases, equivalent ground-truth volume coverage was observed for all methods but for more heterogeneous cases, significantly lower coverage was observed for threshold-based methods. Our study demonstrates that significant dosimetry errors can be avoided by using more advanced image-segmentation methods. (paper)

  15. An adaptive radiotherapy planning strategy for bladder cancer using deformation vector fields

    International Nuclear Information System (INIS)

    Vestergaard, Anne; Kallehauge, Jesper Folsted; Petersen, Jørgen Breede Baltzer; Høyer, Morten; Søndergaard, Jimmi; Muren, Ludvig Paul

    2014-01-01

    Purpose: Adaptive radiotherapy (ART) has considerable potential in treatment of bladder cancer due to large inter-fractional changes in shape and size of the target. The aim of this study was to compare our clinically applied method for plan library creation that involves manual bladder delineations (Clin-ART) with a method using the deformation vector fields (DVFs) resulting from intensity-based deformable image registrations (DVF-based ART). Materials and methods: The study included thirteen patients with urinary bladder cancer who had daily cone beam CTs (CBCTs) acquired for set-up. In both ART strategies investigated, three plan selection volumes were generated using the CBCTs from the first four fractions; in Clin-ART boolean combinations of delineated bladders were used, while the DVF-based strategy applied combinations of the mean and standard deviation of patient-specific DVFs. The volume ratios (VRs) of the course-averaged PTV for the two ART strategies relative the non-adaptive PTV were calculated. Results: Both Clin-ART and DVF-based ART considerably reduced the course-averaged PTV, compared to non-adaptive RT. The VR for DVF-based ART was lower than for Clin-ART (0.65 vs. 0.73; p < 0.01). Conclusions: DVF-based ART for bladder irradiation has a considerable normal tissue sparing potential surpassing our already highly conformal clinically applied ART strategy

  16. An adaptive radiotherapy planning strategy for bladder cancer using deformation vector fields.

    Science.gov (United States)

    Vestergaard, Anne; Kallehauge, Jesper Folsted; Petersen, Jørgen Breede Baltzer; Høyer, Morten; Søndergaard, Jimmi; Muren, Ludvig Paul

    2014-09-01

    Adaptive radiotherapy (ART) has considerable potential in treatment of bladder cancer due to large inter-fractional changes in shape and size of the target. The aim of this study was to compare our clinically applied method for plan library creation that involves manual bladder delineations (Clin-ART) with a method using the deformation vector fields (DVFs) resulting from intensity-based deformable image registrations (DVF-based ART). The study included thirteen patients with urinary bladder cancer who had daily cone beam CTs (CBCTs) acquired for set-up. In both ART strategies investigated, three plan selection volumes were generated using the CBCTs from the first four fractions; in Clin-ART boolean combinations of delineated bladders were used, while the DVF-based strategy applied combinations of the mean and standard deviation of patient-specific DVFs. The volume ratios (VRs) of the course-averaged PTV for the two ART strategies relative the non-adaptive PTV were calculated. Both Clin-ART and DVF-based ART considerably reduced the course-averaged PTV, compared to non-adaptive RT. The VR for DVF-based ART was lower than for Clin-ART (0.65 vs. 0.73; p<0.01). DVF-based ART for bladder irradiation has a considerable normal tissue sparing potential surpassing our already highly conformal clinically applied ART strategy. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. Selection and determination of beam weights based on genetic algorithms for conformal radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Xingen Wu; Zunliang Wang

    2000-01-01

    A genetic algorithm has been used to optimize the selection of beam weights for external beam three-dimensional conformal radiotherapy treatment planning. A fitness function is defined, which includes a difference function to achieve a least-square fit to doses at preselected points in a planning target volume, and a penalty item to constrain the maximum allowable doses delivered to critical organs. Adjustment between the dose uniformity within the target volume and the dose constraint to the critical structures can be achieved by varying the beam weight variables in the fitness function. A floating-point encoding schema and several operators, like uniform crossover, arithmetical crossover, geometrical crossover, Gaussian mutation and uniform mutation, have been used to evolve the population. Three different cases were used to verify the correctness of the algorithm and quality assessment based on dose-volume histograms and three-dimensional dose distributions were given. The results indicate that the genetic algorithm presented here has considerable potential. (author)

  18. Towards the elimination of Monte Carlo statistical fluctuation from dose volume histograms for radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Sempau, J.; Bielajew, A.F.

    2000-01-01

    The Monte Carlo calculation of dose for radiotherapy treatment planning purposes introduces unavoidable statistical noise into the prediction of dose in a given volume element (voxel). When the doses in these voxels are summed to produce dose volume histograms (DVHs), this noise translates into a broadening of differential DVHs and correspondingly flatter DVHs. A brute force approach would entail calculating dose for long periods of time - enough to ensure that the DVHs had converged. In this paper we introduce an approach for deconvolving the statistical noise from DVHs, thereby obtaining estimates for converged DVHs obtained about 100 times faster than the brute force approach described above. There are two important implications of this work: (a) decisions based upon DVHs may be made much more economically using the new approach and (b) inverse treatment planning or optimization methods may employ Monte Carlo dose calculations at all stages of the iterative procedure since the prohibitive cost of Monte Carlo calculations at the intermediate calculation steps can be practically eliminated. (author)

  19. Modulated electron radiotherapy treatment planning using a photon multileaf collimator for post-mastectomized chest walls

    International Nuclear Information System (INIS)

    Salguero, Francisco Javier; Palma, Bianey; Arrans, Rafael; Rosello, Joan; Leal, Antonio

    2009-01-01

    Background and purpose: To evaluate the feasibility of using a photon MLC (xMLC) for modulated electron radiotherapy treatment (MERT) as an alternative to conventional post-mastectomy chest wall (CW) irradiation. A Monte Carlo (MC) based planning system was developed to overcome the inaccuracy of the 'pencil beam' algorithm. MC techniques are known to accurately calculate the dose distributions of electron beams, allowing the explicit simulation of electron interactions within the MLC. Materials and methods: Four real clinical CW cases were planned using MERT which were compared with the conventional electron treatments based on blocks and by a straightforward approach using the MLC, and not the blocks (as an intermediate step to MERT) to shape the same segments with SSD between 60 and 70 cm depending on PTV size. MC calculations were verified with an array of ionization chambers and radiochromic films in a solid water phantom. Results: Tests based on gamma analysis between MC dose distributions and radiochromic film measurements showed an excellent agreement. Differences in the absolute dose measured with a plane-parallel chamber at a reference point were below 3% for all cases. MERT solution showed a better PTV coverage and a significant reduction of the doses to the organs at risk (OARs). Conclusion: MERT can effectively improve the current electron treatments by obtaining a better PTV coverage and sparing healthy tissues. More directly, block-shaped treatments could be replaced by MLC-shaped non-modulated segments providing similar results.

  20. SU-F-T-604: Dosimetric Evaluation of Intracranial Stereotactic Radiotherapy Plans On a LINAC

    Energy Technology Data Exchange (ETDEWEB)

    Sheth, N; Tabibian, A; Rose, J; Alvelo, M; Perel, C; Laiken, K; Kim, A [Bayonne Medical Center, Bayonne, NJ (United States)

    2016-06-15

    Purpose: To evaluate the dosimetry of cranial stereotactic radiotherapy (SRT) plans of varying techniques on linac that meets appropriate TG-142 tolerances using 1 cm leaf width multileaf collimator (MLC). Methods: Seventeen spherical targets were generated in the center of a head phantom with diameters ranging 8 mm to 40 mm. SRT plans used 100° non-coplanar arcs and 5 couch angles with 35° spacing. The field size was target plus 1 mm margin. Four plans were created for each target: symmetrical jaws blocking for 5 arcs with 0° collimator (J1C), symmetrical jaws blocking with 5 clockwise arcs with 0° collimator and 5 counter-clockwise arcs with 45° collimator (J2C), MLC blocking for 5 dynamic conformal arcs with 0° collimator (M1C), and MLC blocking for 5 clockwise dynamic conformal arcs with 0° collimators and 5 counter-clockwise dynamic conformal arcs with 45° collimator (M2C).Conformity was evaluated using a ratio of Rx to target volume (PITV). Heterogeneity was determined using a ratio of maximum dose to Rx dose. Falloff was scored using CGIg: difference of effective radii of spheres equal to half and full Rx volumes. Results: All plans met RTOG SRS criteria for conformity and heterogeneity. The mean PITV was 1.52±0.07, 1.49±0.08, 1.39±0.05, and 1.37±0.04 for J1C, J2C, M1C, and M2C plans respectively. The mean CGIg was 75.35±15.79, 74.19±16.66, 77.14±15.12, and 76.28±15.78 for J1C, J2C, M1C, and M2C plans respectively. The mean MDPD was 1.25±0.00 for all techniques. Conclusion: Clinically acceptable SRT plans for spherical targets were created on a linac with 1 cm MLC. Adding two collimator angles and MLC to arcs each improved conformity. The MLC improved the dose falloff while two collimator angles degraded it. This technique can expand the availability of SRT to patients especially to those who cannot travel to a facility with a dedicated stereotactic radiosurgery machine.

  1. A comparison between anisotropic analytical and multigrid superposition dose calculation algorithms in radiotherapy treatment planning

    International Nuclear Information System (INIS)

    Wu, Vincent W.C.; Tse, Teddy K.H.; Ho, Cola L.M.; Yeung, Eric C.Y.

    2013-01-01

    Monte Carlo (MC) simulation is currently the most accurate dose calculation algorithm in radiotherapy planning but requires relatively long processing time. Faster model-based algorithms such as the anisotropic analytical algorithm (AAA) by the Eclipse treatment planning system and multigrid superposition (MGS) by the XiO treatment planning system are 2 commonly used algorithms. This study compared AAA and MGS against MC, as the gold standard, on brain, nasopharynx, lung, and prostate cancer patients. Computed tomography of 6 patients of each cancer type was used. The same hypothetical treatment plan using the same machine and treatment prescription was computed for each case by each planning system using their respective dose calculation algorithm. The doses at reference points including (1) soft tissues only, (2) bones only, (3) air cavities only, (4) soft tissue-bone boundary (Soft/Bone), (5) soft tissue-air boundary (Soft/Air), and (6) bone-air boundary (Bone/Air), were measured and compared using the mean absolute percentage error (MAPE), which was a function of the percentage dose deviations from MC. Besides, the computation time of each treatment plan was recorded and compared. The MAPEs of MGS were significantly lower than AAA in all types of cancers (p<0.001). With regards to body density combinations, the MAPE of AAA ranged from 1.8% (soft tissue) to 4.9% (Bone/Air), whereas that of MGS from 1.6% (air cavities) to 2.9% (Soft/Bone). The MAPEs of MGS (2.6%±2.1) were significantly lower than that of AAA (3.7%±2.5) in all tissue density combinations (p<0.001). The mean computation time of AAA for all treatment plans was significantly lower than that of the MGS (p<0.001). Both AAA and MGS algorithms demonstrated dose deviations of less than 4.0% in most clinical cases and their performance was better in homogeneous tissues than at tissue boundaries. In general, MGS demonstrated relatively smaller dose deviations than AAA but required longer computation time

  2. SU-F-T-604: Dosimetric Evaluation of Intracranial Stereotactic Radiotherapy Plans On a LINAC

    International Nuclear Information System (INIS)

    Sheth, N; Tabibian, A; Rose, J; Alvelo, M; Perel, C; Laiken, K; Kim, A

    2016-01-01

    Purpose: To evaluate the dosimetry of cranial stereotactic radiotherapy (SRT) plans of varying techniques on linac that meets appropriate TG-142 tolerances using 1 cm leaf width multileaf collimator (MLC). Methods: Seventeen spherical targets were generated in the center of a head phantom with diameters ranging 8 mm to 40 mm. SRT plans used 100° non-coplanar arcs and 5 couch angles with 35° spacing. The field size was target plus 1 mm margin. Four plans were created for each target: symmetrical jaws blocking for 5 arcs with 0° collimator (J1C), symmetrical jaws blocking with 5 clockwise arcs with 0° collimator and 5 counter-clockwise arcs with 45° collimator (J2C), MLC blocking for 5 dynamic conformal arcs with 0° collimator (M1C), and MLC blocking for 5 clockwise dynamic conformal arcs with 0° collimators and 5 counter-clockwise dynamic conformal arcs with 45° collimator (M2C).Conformity was evaluated using a ratio of Rx to target volume (PITV). Heterogeneity was determined using a ratio of maximum dose to Rx dose. Falloff was scored using CGIg: difference of effective radii of spheres equal to half and full Rx volumes. Results: All plans met RTOG SRS criteria for conformity and heterogeneity. The mean PITV was 1.52±0.07, 1.49±0.08, 1.39±0.05, and 1.37±0.04 for J1C, J2C, M1C, and M2C plans respectively. The mean CGIg was 75.35±15.79, 74.19±16.66, 77.14±15.12, and 76.28±15.78 for J1C, J2C, M1C, and M2C plans respectively. The mean MDPD was 1.25±0.00 for all techniques. Conclusion: Clinically acceptable SRT plans for spherical targets were created on a linac with 1 cm MLC. Adding two collimator angles and MLC to arcs each improved conformity. The MLC improved the dose falloff while two collimator angles degraded it. This technique can expand the availability of SRT to patients especially to those who cannot travel to a facility with a dedicated stereotactic radiosurgery machine.

  3. Automated replication of cone beam CT-guided treatments in the Pinnacle(3) treatment planning system for adaptive radiotherapy.

    Science.gov (United States)

    Hargrave, Catriona; Mason, Nicole; Guidi, Robyn; Miller, Julie-Anne; Becker, Jillian; Moores, Matthew; Mengersen, Kerrie; Poulsen, Michael; Harden, Fiona

    2016-03-01

    Time-consuming manual methods have been required to register cone-beam computed tomography (CBCT) images with plans in the Pinnacle(3) treatment planning system in order to replicate delivered treatments for adaptive radiotherapy. These methods rely on fiducial marker (FM) placement during CBCT acquisition or the image mid-point to localise the image isocentre. A quality assurance study was conducted to validate an automated CBCT-plan registration method utilising the Digital Imaging and Communications in Medicine (DICOM) Structure Set (RS) and Spatial Registration (RE) files created during online image-guided radiotherapy (IGRT). CBCTs of a phantom were acquired with FMs and predetermined setup errors using various online IGRT workflows. The CBCTs, DICOM RS and RE files were imported into Pinnacle(3) plans of the phantom and the resulting automated CBCT-plan registrations were compared to existing manual methods. A clinical protocol for the automated method was subsequently developed and tested retrospectively using CBCTs and plans for six bladder patients. The automated CBCT-plan registration method was successfully applied to thirty-four phantom CBCT images acquired with an online 0 mm action level workflow. Ten CBCTs acquired with other IGRT workflows required manual workarounds. This was addressed during the development and testing of the clinical protocol using twenty-eight patient CBCTs. The automated CBCT-plan registrations were instantaneous, replicating delivered treatments in Pinnacle(3) with errors of ±0.5 mm. These errors were comparable to mid-point-dependant manual registrations but superior to FM-dependant manual registrations. The automated CBCT-plan registration method quickly and reliably replicates delivered treatments in Pinnacle(3) for adaptive radiotherapy.

  4. T2-weighted four dimensional magnetic resonance imaging with result-driven phase sorting

    International Nuclear Information System (INIS)

    Liu, Yilin; Yin, Fang-Fang; Cai, Jing; Czito, Brian G.; Bashir, Mustafa R.

    2015-01-01

    Purpose: T2-weighted MRI provides excellent tumor-to-tissue contrast for target volume delineation in radiation therapy treatment planning. This study aims at developing a novel T2-weighted retrospective four dimensional magnetic resonance imaging (4D-MRI) phase sorting technique for imaging organ/tumor respiratory motion. Methods: A 2D fast T2-weighted half-Fourier acquisition single-shot turbo spin-echo MR sequence was used for image acquisition of 4D-MRI, with a frame rate of 2–3 frames/s. Respiratory motion was measured using an external breathing monitoring device. A phase sorting method was developed to sort the images by their corresponding respiratory phases. Besides, a result-driven strategy was applied to effectively utilize redundant images in the case when multiple images were allocated to a bin. This strategy, selecting the image with minimal amplitude error, will generate the most representative 4D-MRI. Since we are using a different image acquisition mode for 4D imaging (the sequential image acquisition scheme) with the conventionally used cine or helical image acquisition scheme, the 4D dataset sufficient condition was not obviously and directly predictable. An important challenge of the proposed technique was to determine the number of repeated scans (N_R) required to obtain sufficient phase information at each slice position. To tackle this challenge, the authors first conducted computer simulations using real-time position management respiratory signals of the 29 cancer patients under an IRB-approved retrospective study to derive the relationships between N_R and the following factors: number of slices (N_S), number of 4D-MRI respiratory bins (N_B), and starting phase at image acquisition (P_0). To validate the authors’ technique, 4D-MRI acquisition and reconstruction were simulated on a 4D digital extended cardiac-torso (XCAT) human phantom using simulation derived parameters. Twelve healthy volunteers were involved in an IRB-approved study

  5. Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Min; Kim, Jung-in; Heon Choi, Chang; Chie, Eui Kyu; Kim, Il Han; Ye, Sung-Joon [Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744, Korea and Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of) and Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of) and Department of Intelligent Convergence Systems, Seoul National University, Seoul, 151-742 (Korea, Republic of)

    2012-03-15

    Purpose: To demonstrate the feasibility of photon energy-modulated radiotherapy during beam-on time. Methods: A cylindrical device made of aluminum was conceptually proposed as an energy modulator. The frame of the device was connected with 20 tubes through which mercury could be injected or drained to adjust the thickness of mercury along the beam axis. In Monte Carlo (MC) simulations, a flattening filter of 6 or 10 MV linac was replaced with the device. The thickness of mercury inside the device varied from 0 to 40 mm at the field sizes of 5 x 5 cm{sup 2} (FS5), 10 x 10 cm{sup 2} (FS10), and 20 x 20 cm{sup 2} (FS20). At least 5 billion histories were followed for each simulation to create phase space files at 100 cm source to surface distance (SSD). In-water beam data were acquired by additional MC simulations using the above phase space files. A treatment planning system (TPS) was commissioned to generate a virtual machine using the MC-generated beam data. Intensity modulated radiation therapy (IMRT) plans for six clinical cases were generated using conventional 6 MV, 6 MV flattening filter free, and energy-modulated photon beams of the virtual machine. Results: As increasing the thickness of mercury, Percentage depth doses (PDD) of modulated 6 and 10 MV after the depth of dose maximum were continuously increased. The amount of PDD increase at the depth of 10 and 20 cm for modulated 6 MV was 4.8% and 5.2% at FS5, 3.9% and 5.0% at FS10 and 3.2%-4.9% at FS20 as increasing the thickness of mercury from 0 to 20 mm. The same for modulated 10 MV was 4.5% and 5.0% at FS5, 3.8% and 4.7% at FS10 and 4.1% and 4.8% at FS20 as increasing the thickness of mercury from 0 to 25 mm. The outputs of modulated 6 MV with 20 mm mercury and of modulated 10 MV with 25 mm mercury were reduced into 30%, and 56% of conventional linac, respectively. The energy-modulated IMRT plans had less integral doses than 6 MV IMRT or 6 MV flattening filter free plans for tumors located in the

  6. Individualized margins in 3D conformal radiotherapy planning for lung cancer: analysis of physiological movements and their dosimetric impacts.

    Science.gov (United States)

    Germain, François; Beaulieu, Luc; Fortin, André

    2008-01-01

    In conformal radiotherapy planning for lung cancer, respiratory movements are not taken into account when a single computed tomography (CT) scan is performed. This study examines tumor movements to design individualized margins to account for these movements and evaluates their dosimetric impacts on planning volume. Fifteen patients undergoing CT-based planning for radical radiotherapy for localized lung cancer formed the study cohort. A reference plan was constructed based on reference gross, clinical, and planning target volumes (rGTV, rCTV, and rPTV, respectively). The reference plans were compared with individualized plans using individualized margins obtained by using 5 serial CT scans to generate individualized target volumes (iGTV, iCTV, and iPTV). Three-dimensional conformal radiation therapy was used for plan generation using 6- and 23-MV photon beams. Ten plans for each patient were generated and dose-volume histograms (DVHs) were calculated. Comparisons of volumetric and dosimetric parameters were performed using paired Student t-tests. Relative to the rGTV, the total volume occupied by the superimposed GTVs increased progressively with each additional CT scans. With the use of all 5 scans, the average increase in GTV was 52.1%. For the plans with closest dosimetric coverage, target volume was smaller (iPTV/rPTV ratio 0.808) but lung irradiation was only slightly decreased. Reduction in the proportion of lung tissue that received 20 Gy or more outside the PTV (V20) was observed both for 6-MV plans (-0.73%) and 23-MV plans (-0.65%), with p = 0.02 and p = 0.04, respectively. In conformal RT planning for the treatment of lung cancer, the use of serial CT scans to evaluate respiratory motion and to generate individualized margins to account for these motions produced only a limited lung sparing advantage.

  7. Individualized Margins in 3D Conformal Radiotherapy Planning for Lung Cancer: Analysis of Physiological Movements and Their Dosimetric Impacts

    International Nuclear Information System (INIS)

    Germain, Francois; Beaulieu, Luc; Fortin, Andre

    2008-01-01

    In conformal radiotherapy planning for lung cancer, respiratory movements are not taken into account when a single computed tomography (CT) scan is performed. This study examines tumor movements to design individualized margins to account for these movements and evaluates their dosimetric impacts on planning volume. Fifteen patients undergoing CT-based planning for radical radiotherapy for localized lung cancer formed the study cohort. A reference plan was constructed based on reference gross, clinical, and planning target volumes (rGTV, rCTV, and rPTV, respectively). The reference plans were compared with individualized plans using individualized margins obtained by using 5 serial CT scans to generate individualized target volumes (iGTV, iCTV, and iPTV). Three-dimensional conformal radiation therapy was used for plan generation using 6- and 23-MV photon beams. Ten plans for each patient were generated and dose-volume histograms (DVHs) were calculated. Comparisons of volumetric and dosimetric parameters were performed using paired Student t-tests. Relative to the rGTV, the total volume occupied by the superimposed GTVs increased progressively with each additional CT scans. With the use of all 5 scans, the average increase in GTV was 52.1%. For the plans with closest dosimetric coverage, target volume was smaller (iPTV/rPTV ratio 0.808) but lung irradiation was only slightly decreased. Reduction in the proportion of lung tissue that received 20 Gy or more outside the PTV (V20) was observed both for 6-MV plans (-0.73%) and 23-MV plans (-0.65%), with p = 0.02 and p = 0.04, respectively. In conformal RT planning for the treatment of lung cancer, the use of serial CT scans to evaluate respiratory motion and to generate individualized margins to account for these motions produced only a limited lung sparing advantage

  8. Quantitative comparison of volumetric modulated arc therapy and intensity modulated radiotherapy plan quality in sino-nasal cancer

    International Nuclear Information System (INIS)

    Sankaralingam, Marimuthu; Glegg, Martin; Smith, Suzanne; James, Allan; Rizwanullah, Mohammed

    2012-01-01

    The aim of this study was to compare various dosimetric parameters of dynamic mlc intensity modulated radiotherapy (IMRT) plans with volumetric modulated arc therapy (VMAT) plans for sino-nasal cancers, which are rare and complex tumors to treat with radiotherapy. IMRT using five fields, coplanar in the sagittal plane and VMAT employing two coplanar arc plans were created for five patients. The plans were assessed by comparing Conformity Index and Sigma Index (dose homogeneity) in the Planning Target Volume (PTV) and through comparison of dose-volume characteristics to the following organs at risk (OARs): Spinal cord, brainstem, eye, ipsilateral and contralateral optic nerve and the volume of brain receiving 10% of the prescribed dose (V 10% ). The total monitor units required to deliver the plan were also compared. Conformity Index was found to be superior in VMAT plans for three patients and in IMRT plans for two patients. Dose homogeneity within the PTV was better with VMAT plans for all five cases. The mean difference in Sigma Index was 0.68%. There was no significant difference in dose between IMRT and VMAT plans for any of the OARs assessed in these patients. The monitor units were significantly reduced in the VMAT plan in comparison to the IMRT plan for four out of five patients, with mean reduction of 66%. It was found in this study that for the treatment of sino-nasal cancer, VMAT produced minimal, and statistically insignificant improvement in dose homogeneity within the PTV when compared with IMRT. VMAT plans were delivered using significantly fewer monitor units. We conclude in this study that VMAT does not offer significant improvement of treatment for sino-nasal cancer over the existing IMRT techniques, but the findings may change with a larger sample of patients in this rare condition. (author)

  9. A four-dimensional variational chemistry data assimilation scheme for Eulerian chemistry transport modeling

    Science.gov (United States)

    Eibern, Hendrik; Schmidt, Hauke

    1999-08-01

    The inverse problem of data assimilation of tropospheric trace gas observations into an Eulerian chemistry transport model has been solved by the four-dimensional variational technique including chemical reactions, transport, and diffusion. The University of Cologne European Air Pollution Dispersion Chemistry Transport Model 2 with the Regional Acid Deposition Model 2 gas phase mechanism is taken as the basis for developing a full four-dimensional variational data assimilation package, on the basis of the adjoint model version, which includes the adjoint operators of horizontal and vertical advection, implicit vertical diffusion, and the adjoint gas phase mechanism. To assess the potential and limitations of the technique without degrading the impact of nonperfect meteorological analyses and statistically not established error covariance estimates, artificial meteorological data and observations are used. The results are presented on the basis of a suite of experiments, where reduced records of artificial "observations" are provided to the assimilation procedure, while other "data" is retained for performance control of the analysis. The paper demonstrates that the four-dimensional variational technique is applicable for a comprehensive chemistry transport model in terms of computational and storage requirements on advanced parallel platforms. It is further shown that observed species can generally be analyzed, even if the "measurements" have unbiased random errors. More challenging experiments are presented, aiming to tax the skill of the method (1) by restricting available observations mostly to surface ozone observations for a limited assimilation interval of 6 hours and (2) by starting with poorly chosen first guess values. In this first such application to a three-dimensional chemistry transport model, success was also achieved in analyzing not only observed but also chemically closely related unobserved constituents.

  10. Magnetic resonance imaging for prostate bed radiotherapy planning: An inter- and intra-observer variability study

    International Nuclear Information System (INIS)

    Barkati, Maroie; Simard, Dany; Taussky, Daniel; Delouya, Guiula

    2016-01-01

    We assessed the inter- and intra-observer variability in contouring the prostate bed for radiation therapy planning using MRI compared with computed tomography (CT). We selected 15 patients with prior radical prostatectomy. All had CT and MRI simulation for planning purposes. Image fusions were done between CT and MRI. Three radiation oncologists with several years of experience in treating prostate cancer contoured the prostate bed first on CT and then on MRI. Before contouring, each radiation oncologist had to review the Radiation Therapy Oncology Group guidelines for postoperative external beam radiotherapy. The agreement between volumes was calculated using the Dice similarity coefficient (DSC). Analysis was done using the Matlab software. The DSC was compared using non-parametric statistical tests. Contouring on CT alone showed a statistically significant (P = 0.001) higher similarity between observers with a mean DSC of 0.76 (standard deviation ± 0.05) compared with contouring on MRI with a mean of 0.66 (standard deviation ± 0.05). Mean intra-observer variability between CT and MRI was 0.68, 0.75 and 0.78 for the three observers. The clinical target volume was 19 - 74% larger on CT than on MRI. The intra-observer difference in clinical target volume between CT and MRI was statistically significant in two observers and non-significant in the third one (P = 0.09). We found less inter-observer variability when contouring on CT than on MRI. Radiation Therapy Oncology Group contouring guidelines are based on anatomical landmarks readily visible on CT. These landmarks are more inter-observer dependent on MRI. Therefore, present contouring guidelines might not be applicable to MRI planning.

  11. Whole-pelvic radiotherapy with spot-scanning proton beams for uterine cervical cancer: a planning study

    International Nuclear Information System (INIS)

    Hashimoto, Shingo; Shibamoto, Yuta; Iwata, Hiromitsu; Ogino, Hiroyuki; Shibata, Hiroki; Toshito, Toshiyuki; Sugie, Chikao; Mizoe, Jun-etsu

    2016-01-01

    The aim of this study was to compare the dosimetric parameters of whole-pelvic radiotherapy (WPRT) for cervical cancer among plans involving 3D conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), or spot-scanning proton therapy (SSPT). The dose distributions of 3D-CRT-, IMRT-, and SSPT-based WPRT plans were compared in 10 patients with cervical cancer. All of the patients were treated with a prescribed dose of 50.4 Gy in 1.8-Gy daily fractions, and all of the plans involved the same planning target volume (PTV) constrictions. A 3D-CRT plan involving a four-field box, an IMRT plan involving seven coplanar fields, and an SSPT plan involving four fields were created. The median PTV D95% did not differ between the 3D-CRT, IMRT and SSPT plans. The median conformity index 95% and homogeneity index of the IMRT and SSPT were better than those of the 3D-CRT. The homogeneity index of the SSPT was better than that of the IMRT. SSPT resulted in lower median V20 values for the bladder wall, small intestine, colon, bilateral femoral heads, skin, and pelvic bone than IMRT. Comparing the Dmean values, SSPT spared the small intestine, colon, bilateral femoral heads, skin and pelvic bone to a greater extent than the other modalities. SSPT can reduce the irradiated volume of the organs at risk compared with 3D-CRT and IMRT, while maintaining excellent PTV coverage. Further investigations of SSPT are warranted to assess its role in the treatment of cervical cancer.

  12. Four-dimensional imaging of the initial stage of fast evolving plasmas

    International Nuclear Information System (INIS)

    Zhu Pengfei; Wang Weimin; Zhang Zhongchao; Chen Long; Zheng Jun; Li Runze; Qian Dong; Li Junjie; Wang Xuan; Cao Jianming; Sheng Zhengming; Zhang Jie

    2010-01-01

    Using an ultrafast electron probe capable of four-dimensional diagnosis, the initial stage of fast evolving plasmas produced by a 10 14 W/cm 2 laser irradiation of a metal target was investigated in real time with picosecond time resolution. The associated strong transient electric field was identified to have two components, which either focus or defocus the probe electron beam. The effects of this field on the probe electron beam can be reproduced by a self-expanding charge cloud containing about 5x10 7 suprathermal electrons with the outermost layer expanding at an average speed of 1.2x10 7 m/s.

  13. Non-critical string duals of four-dimensional CFTs with fundamental matter

    International Nuclear Information System (INIS)

    Bigazzi, F.; Casero, R.; Paredes, A.; Cotrone, A.L.

    2006-01-01

    The two-derivative approximation to non-critical strings is used as a qualitative tool to find solutions dual to four dimensional CFTs with matter in the fundamental. Two solutions are discussed: an AdS 5 x S 3 , which is dual to an N=1 SCFT only for a ratio of N f /N c and an AdS 5 which is proposed to be dual to N=0 QCD in the conformal window. All solutions have curvatures of the order of the string scale. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  14. Post-Newtonian approximation of the maximum four-dimensional Yang-Mills gauge theory

    International Nuclear Information System (INIS)

    Smalley, L.L.

    1982-01-01

    We have calculated the post-Newtonian approximation of the maximum four-dimensional Yang-Mills theory proposed by Hsu. The theory contains torsion; however, torsion is not active at the level of the post-Newtonian approximation of the metric. Depending on the nature of the approximation, we obtain the general-relativistic values for the classical Robertson parameters (γ = β = 1), but deviations for the Nordtvedt effect and violations of post-Newtonian conservation laws. We conclude that in its present form the theory is not a viable theory of gravitation

  15. Bifurcation structures and transient chaos in a four-dimensional Chua model

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, Anderson, E-mail: hoffande@gmail.com; Silva, Denilson T. da; Manchein, Cesar, E-mail: cesar.manchein@udesc.br; Albuquerque, Holokx A., E-mail: holokx.albuquerque@udesc.br

    2014-01-10

    A four-dimensional four-parameter Chua model with cubic nonlinearity is studied applying numerical continuation and numerical solutions methods. Regarding numerical solution methods, its dynamics is characterized on Lyapunov and isoperiodic diagrams and regarding numerical continuation method, the bifurcation curves are obtained. Combining both methods the bifurcation structures of the model were obtained with the possibility to describe the shrimp-shaped domains and their endoskeletons. We study the effect of a parameter that controls the dimension of the system leading the model to present transient chaos with its corresponding basin of attraction being riddled.

  16. Four-dimensional (4D) tracking of high-temperature microparticles

    International Nuclear Information System (INIS)

    Wang, Zhehui; Liu, Q.; Waganaar, W.; Fontanese, J.; James, D.; Munsat, T.

    2016-01-01

    High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. Velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

  17. 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.)

  18. Finite-temperature symmetry restoration in the four-dimensional Φ4 model with four components

    International Nuclear Information System (INIS)

    Jansen, K.

    1990-01-01

    The finite-temperature symmetry restoration in the four-dimensional φ 4 theory with four components and with an infinite self-coupling is studied by means of Monte Carlo simulations on lattices with time extensions L t =4,5,6 and space extensions 12 3 -28 3 . The numerical calculations are done by means of the Wolff cluster algorithm which is very efficient for simulations near a phase transition. The numerical results are in good agreement with an improved one-loop expansion and with the 1/N-expansion, indicating that in the electroweak theory the symmetry restoration temperature T sr is about 350 GeV. (orig.)

  19. An accessible four-dimensional treatment of Maxwell's equations in terms of differential forms

    Science.gov (United States)

    Sá, Lucas

    2017-03-01

    Maxwell’s equations are derived in terms of differential forms in the four-dimensional Minkowski representation, starting from the three-dimensional vector calculus differential version of these equations. Introducing all the mathematical and physical concepts needed (including the tool of differential forms), using only knowledge of elementary vector calculus and the local vector version of Maxwell’s equations, the equations are reduced to a simple and elegant set of two equations for a unified quantity, the electromagnetic field. The treatment should be accessible for students taking a first course on electromagnetism.

  20. Analysis of interfractional variations in pancreatic position based on four-dimensional computed tomography

    International Nuclear Information System (INIS)

    Shiinoki, Takehiro; Itoh, Akio; Shibuya, Keiko; Nakamura, Mitsuhiro; Nakamura, Akira; Matsuo, Yukinori; Sawada, Akira; Mizowaki, Takashi; Hiraoka, Masahiro

    2010-01-01

    The purpose of this study was to assess inter-fractional variations in pancreatic position using four-dimensional computed tomography (4D-CT) and to find the suitable phase of respiration for breath-holding. The variations in respiratory motion range during treatment course and inter-fractional variations in pancreatic positions were not negligible; however, our study suggested that breath-holding at end-exhalation with some coaching techniques might be considerable one of the non-invasive approaches to get higher positional reproducibility of pancreatic tumors. (author)

  1. Four-dimensional Hooke's law can encompass linear elasticity and inertia

    International Nuclear Information System (INIS)

    Antoci, S.; Mihich, L.

    1999-01-01

    The question is examined whether the formally straightforward extension of Hooke's time-honoured stress-strain relation to the four dimensions of special and of general relativity can make physical sense. The four-dimensional Hooke law is found able to account for the inertia of matter; in the flat-space, slow-motion approximation the field equations for the displacement four-vector field ξ i can encompass both linear elasticity and inertia. In this limit one just recovers the equations of motion of the classical theory of elasticity

  2. One-way quantum computation with four-dimensional photonic qudits

    International Nuclear Information System (INIS)

    Joo, Jaewoo; Knight, Peter L.; O'Brien, Jeremy L.; Rudolph, Terry

    2007-01-01

    We consider the possibility of performing linear optical quantum computations making use of extra photonic degrees of freedom. In particular, we focus on the case where we use photons as quadbits, four-dimensional photonic qudits. The basic 2-quadbit cluster state is a hyperentangled state across polarization and two spatial mode degrees of freedom. We examine the nondeterministic methods whereby such states can be created from single photons and/or Bell pairs and then give some mechanisms for performing higher-dimensional fusion gates

  3. Gravitational matter-antimatter asymmetry and four-dimensional Yang-Mills gauge symmetry

    Science.gov (United States)

    Hsu, J. P.

    1981-01-01

    A formulation of gravity based on the maximum four-dimensional Yang-Mills gauge symmetry is studied. The theory predicts that the gravitational force inside matter (fermions) is different from that inside antimatter. This difference could lead to the cosmic separation of matter and antimatter in the evolution of the universe. Moreover, a new gravitational long-range spin-force between two fermions is predicted, in addition to the usual Newtonian force. The geometrical foundation of such a gravitational theory is the Riemann-Cartan geometry, in which there is a torsion. The results of the theory for weak fields are consistent with previous experiments.

  4. Feasibility of using intensity-modulated radiotherapy to improve lung sparing in treatment planning for distal esophageal cancer

    International Nuclear Information System (INIS)

    Chandra, Anurag; Guerrero, Thomas M.; Liu, H. Helen; Tucker, Susan L.; Liao Zhongxing; Wang Xiaochun; Murshed, Hasan; Bonnen, Mark D.; Garg, Amit K.; Stevens, Craig W.; Chang, Joe Y.; Jeter, Melinda D.; Mohan, Radhe; Cox, James D.; Komaki, Ritsuko

    2005-01-01

    Background and purpose: To evaluate the feasibility whether intensity-modulated radiotherapy (IMRT) can be used to reduce doses to normal lung than three-dimensional conformal radiotherapy (3DCRT) in treating distal esophageal malignancies. Patients and methods: Ten patient cases with cancer of the distal esophagus were selected for a retrospective treatment-planning study. IMRT plans using four, seven, and nine beams (4B, 7B, and 9B) were developed for each patient and compared with the 3DCRT plan used clinically. IMRT and 3DCRT plans were evaluated with respect to PTV coverage and dose-volumes to irradiated normal structures, with statistical comparison made between the two types of plans using the Wilcoxon matched-pair signed-rank test. Results: IMRT plans (4B, 7B, 9B) reduced total lung volume treated above 10 Gy (V 1 ), 20 Gy (V 2 ), mean lung dose (MLD), biological effective volume (V eff ), and lung integral dose (P 1 , 5% for V 2 , and 2.5 Gy for MLD. IMRT improved the PTV heterogeneity (P<0.05), yet conformity was better with 7B-9B IMRT plans. No clinically meaningful differences were observed with respect to the irradiated volumes of spinal cord, heart, liver, or total body integral doses. Conclusions: Dose-volume of exposed normal lung can be reduced with IMRT, though clinical investigations are warranted to assess IMRT treatment outcome of esophagus cancers

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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

  6. Dosimetric and Radiobiologic Comparison of 3D Conformal Versus Intensity Modulated Planning Techniques for Prostate Bed Radiotherapy

    International Nuclear Information System (INIS)

    Koontz, Bridget F.; Das, Shiva; Temple, Kathy; Bynum, Sigrun; Catalano, Suzanne; Koontz, Jason I.; Montana, Gustavo S.; Oleson, James R.

    2009-01-01

    Adjuvant radiotherapy for locally advanced prostate cancer improves biochemical and clinical disease-free survival. While comparisons in intact prostate cancer show a benefit for intensity modulated radiation therapy (IMRT) over 3D conformal planning, this has not been studied for post-prostatectomy radiotherapy (RT). This study compares normal tissue and target dosimetry and radiobiological modeling of IMRT vs. 3D conformal planning in the postoperative setting. 3D conformal plans were designed for 15 patients who had been treated with IMRT planning for salvage post-prostatectomy RT. The same computed tomography (CT) and target/normal structure contours, as well as prescription dose, was used for both IMRT and 3D plans. Normal tissue complication probabilities (NTCPs) were calculated based on the dose given to the bladder and rectum by both plans. Dose-volume histogram and NTCP data were compared by paired t-test. Bladder and rectal sparing were improved with IMRT planning compared to 3D conformal planning. The volume of the bladder receiving at least 75% (V75) and 50% (V50) of the dose was significantly reduced by 28% and 17%, respectively (p = 0.002 and 0.037). Rectal dose was similarly reduced, V75 by 33% and V50 by 17% (p = 0.001 and 0.004). While there was no difference in the volume of rectum receiving at least 65 Gy (V65), IMRT planning significant reduced the volume receiving 40 Gy or more (V40, p = 0.009). Bladder V40 and V65 were not significantly different between planning modalities. Despite these dosimetric differences, there was no significant difference in the NTCP for either bladder or rectal injury. IMRT planning reduces the volume of bladder and rectum receiving high doses during post-prostatectomy RT. Because of relatively low doses given to the bladder and rectum, there was no statistically significant improvement in NTCP between the 3D conformal and IMRT plans.

  7. Dosimetric and radiobiologic comparison of 3D conformal versus intensity modulated planning techniques for prostate bed radiotherapy.

    Science.gov (United States)

    Koontz, Bridget F; Das, Shiva; Temple, Kathy; Bynum, Sigrun; Catalano, Suzanne; Koontz, Jason I; Montana, Gustavo S; Oleson, James R

    2009-01-01

    Adjuvant radiotherapy for locally advanced prostate cancer improves biochemical and clinical disease-free survival. While comparisons in intact prostate cancer show a benefit for intensity modulated radiation therapy (IMRT) over 3D conformal planning, this has not been studied for post-prostatectomy radiotherapy (RT). This study compares normal tissue and target dosimetry and radiobiological modeling of IMRT vs. 3D conformal planning in the postoperative setting. 3D conformal plans were designed for 15 patients who had been treated with IMRT planning for salvage post-prostatectomy RT. The same computed tomography (CT) and target/normal structure contours, as well as prescription dose, was used for both IMRT and 3D plans. Normal tissue complication probabilities (NTCPs) were calculated based on the dose given to the bladder and rectum by both plans. Dose-volume histogram and NTCP data were compared by paired t-test. Bladder and rectal sparing were improved with IMRT planning compared to 3D conformal planning. The volume of the bladder receiving at least 75% (V75) and 50% (V50) of the dose was significantly reduced by 28% and 17%, respectively (p = 0.002 and 0.037). Rectal dose was similarly reduced, V75 by 33% and V50 by 17% (p = 0.001 and 0.004). While there was no difference in the volume of rectum receiving at least 65 Gy (V65), IMRT planning significant reduced the volume receiving 40 Gy or more (V40, p = 0.009). Bladder V40 and V65 were not significantly different between planning modalities. Despite these dosimetric differences, there was no significant difference in the NTCP for either bladder or rectal injury. IMRT planning reduces the volume of bladder and rectum receiving high doses during post-prostatectomy RT. Because of relatively low doses given to the bladder and rectum, there was no statistically significant improvement in NTCP between the 3D conformal and IMRT plans.

  8. Training, abilities, role and responsibilities of the technician in treatment planning or 'dosimetrist' in radiotherapy

    International Nuclear Information System (INIS)

    Buchheit, Isabelle; Angles, Damien; Marchesi, Vincent; Fau, Pierre; Aubignac, Leone; Palisson, Jeremy; Lacornerie, Thomas; Baron, Pierre-Louis; Popoff, Romain; Llagostera, Camille; Buffard, Edwige; Sarrazin, Thierry; Le Du, Dominique; Estivalet, Andre; Tchong, Bruno; Marcie, Serge; Guerin, Lucie; Parent, Laure

    2013-09-01

    As the creation of treatment plans in radiotherapy (commonly named dosimetry) has become a crucial task in the treatment process, and has been historically performed by the medical physician, it may be delegated to other professionals and there is therefore a need of creation of a profession: the technician in treatment planning or dosimetrist. In order to better define this profession, its role and its education and training requirements, this document describes its role, its required knowledge, abilities and capacities (general knowledge, knowledge in anatomy, oncology and imagery, in radiation production, in ballistic and preparation, in radiotherapy, in breath-based feedback, in body irradiation, in radiation protection, in delimitation of organs at risk, and in administrative issues). The different training levels are indicated: initial training, continuous training, and validation of prior experience. The legal framework and organisational issues are addressed in terms of delegation and responsibility

  9. Value of magnetic resonance imaging in the radiotherapy planning of tumours of the uterine cervix: preliminary results

    International Nuclear Information System (INIS)

    Justino, Pitagoras Baskara; Carvalho, Heloisa de Andrade; Baroni, Ronaldo Hueb; Blasbalg, Roberto; Leite, Claudia da Costa

    2005-01-01

    Objective: To assess the rate of geographic miss on conventional radiotherapy planning of patients with cervical cancer, using magnetic resonance imaging. Materials and methods: Thirty-two patients with squamous cell carcinoma of the uterine cervix were studied. Magnetic resonance imaging of the pelvis was performed after clinical staging. Magnetic resonance imaging findings were compared with the classic fields described for the 'box' technique. Target volume within less than 1 cm margins of the fields' limits was considered as geographic miss. Results: Classical radiation field limits were inadequate in 24 cases (75%), all in the anterior (46%) or posterior (40%) border of the lateral fields. Conclusion: Magnetic resonance detected a high probability of geographic miss on conventional radiotherapy planning in this population, both in initial and advanced stages of the disease. (author)

  10. Toxicity and dosimetric analysis of non-small cell lung cancer patients undergoing radiotherapy with 4DCT and image-guided intensity modulated radiotherapy: a regional centre's experience.

    Science.gov (United States)

    Livingston, Gareth C; Last, Andrew J; Shakespeare, Thomas P; Dwyer, Patrick M; Westhuyzen, Justin; McKay, Michael J; Connors, Lisa; Leader, Stephanie; Greenham, Stuart

    2016-09-01

    For patients receiving radiotherapy for locally advance non-small cell lung cancer (NSCLC), the probability of experiencing severe radiation pneumonitis (RP) appears to rise with an increase in radiation received by the lungs. Intensity modulated radiotherapy (IMRT) provides the ability to reduce planned doses to healthy organs at risk (OAR) and can potentially reduce treatment-related side effects. This study reports toxicity outcomes and provides a dosimetric comparison with three-dimensional conformal radiotherapy (3DCRT). Thirty curative NSCLC patients received radiotherapy using four-dimensional computed tomography and five-field IMRT. All were assessed for early and late toxicity using common terminology criteria for adverse events. All plans were subsequently re-planned using 3DCRT to the same standard as the clinical plans. Dosimetric parameters for lungs, oesophagus, heart and conformity were recorded for comparison between the two techniques. IMRT plans achieved improved high-dose conformity and reduced OAR doses including lung volumes irradiated to 5-20 Gy. One case each of oesophagitis and erythema (3%) were the only Grade 3 toxicities. Rates of Grade 2 oesophagitis were 40%. No cases of Grade 3 RP were recorded and Grade 2 RP rates were as low as 3%. IMRT provides a dosimetric benefit when compared to 3DCRT. While the clinical benefit appears to increase with increasing target size and increasing complexity, IMRT appears preferential to 3DCRT in the treatment of NSCLC.

  11. 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.

  12. On the four-dimensional character of micro-physical phenomena

    International Nuclear Information System (INIS)

    Rietdijk, C.W.

    1984-01-01

    It is proved that retroactive effects exist in Nature. This emphasizes the fact that micro-processes constitute integrated wholes so much that it is no longer far-fetched to posit the hypothesis that events, that is, action, rather than objects, constitute the proper stuff of the (four-dimensional) Universe. Mind here, too, that retroactivity implies that the future and future parts of events 'exist already'. Then, distances between (e.g., alternative) events A and B have to be measured by the quantity of 'occurring' or action that is needed in order to transform event A into event B. The action metric so introduced appears to be in a position to solve the nonlocality paradoxes of quantum mechanics such as wave-particle 'duality' and the EPR paradox. In this connection, the Minkowski metric corresponds to a macro scheme which cannot be 'interpolated' to within a micro-process, i.e., to within action quanta, without producing serious metrical distortions. Generally, metric is considered to be a property of events, it having no existence independent of them as a 'pre-existing scheme'. Planck's elementary quantities of action h are seen as real entities in the four-dimensional world, i.e., as the 'atoms of occurring'. By intersecting (dilated) series of them with a now-hyperplane we in an imaginable way get the wave patterns satisfying the relevant wave equation. (Auth.)

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

    International Nuclear Information System (INIS)

    Smith Stegen, Karen; Palovic, Martin

    2014-01-01

    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

  14. Cardiac imaging using 256-detector row four-dimensional CT. Preliminary clinical report

    International Nuclear Information System (INIS)

    Kido, Teruhito; Kurata, Akira; Higashino, Hiroshi

    2007-01-01

    Along with the increase of detector rows on the z-axis and a faster gantry rotation speed, the spatial and temporal resolutions of the multislice computed tomography (CT) have been improved for noninvasive coronary artery imaging. We investigated the feasibility of the second specification prototype 256-detector row four-dimensional CT for assessing coronary artery and cardiac function. The subjects were five patients with coronary artery disease. Contrast medium (40-60 ml) was intravenously administered at the rate of 3-4 ml/s. The patient's whole heart was scanned for 1.5 s to cover at least one cardiac cycle during breathholding without electrocardiographic gating. Parameters used were 0.5 mm slice thickness, 0.5 s/rotation, 120 Kv, and 350 mA, with a half-scan reconstruction algorithm (temporal resolution 250 ms). Twenty-six transaxial datasets were reconstructed at intervals of 50 ms. The assessability of the coronary arteries in American Heart Association (AHA) segments 1, 2, 3, 5, 6, 7, 9, and 11 was visually evaluated, resulting in 29 of 32 (90.9%) segments being assessable. Functional assessment was also performed using animated movies without banding artifacts in all cases. The 256-detector row four-dimensional CT can assess the coronary artery and cardiac function using data during 1.5 s without banding artifacts. (author)

  15. Four dimensional chaos and intermittency in a mesoscopic model of the electroencephalogram.

    Science.gov (United States)

    Dafilis, Mathew P; Frascoli, Federico; Cadusch, Peter J; Liley, David T J

    2013-06-01

    The occurrence of so-called four dimensional chaos in dynamical systems represented by coupled, nonlinear, ordinary differential equations is rarely reported in the literature. In this paper, we present evidence that Liley's mesoscopic theory of the electroencephalogram (EEG), which has been used to describe brain activity in a variety of clinically relevant contexts, possesses a chaotic attractor with a Kaplan-Yorke dimension significantly larger than three. This accounts for simple, high order chaos for a physiologically admissible parameter set. Whilst the Lyapunov spectrum of the attractor has only one positive exponent, the contracting dimensions are such that the integer part of the Kaplan-Yorke dimension is three, thus giving rise to four dimensional chaos. A one-parameter bifurcation analysis with respect to the parameter corresponding to extracortical input is conducted, with results indicating that the origin of chaos is due to an inverse period doubling cascade. Hence, in the vicinity of the high order, strange attractor, the model is shown to display intermittent behavior, with random alternations between oscillatory and chaotic regimes. This phenomenon represents a possible dynamical justification of some of the typical features of clinically established EEG traces, which can arise in the case of burst suppression in anesthesia and epileptic encephalopathies in early infancy.

  16. Charged rotating black holes in four-dimensional gauged and ungauged supergravities

    International Nuclear Information System (INIS)

    Chong, Z.-W.; Cvetic, M.; Lue, H.; Pope, C.N.

    2005-01-01

    We study four-dimensional non-extremal charged rotating black holes in ungauged and gauged supergravity. In the ungauged case, we obtain rotating black holes with four independent charges, as solutions of N=2 supergravity coupled to three Abelian vector multiplets. This is done by reducing the theory along the time direction to three dimensions, where it has an O(4,4) global symmetry. Applied to the reduction of the uncharged Kerr metric, O(1,1) 4 is a subject of O(4,4) transformations generate new solutions that correspond, after lifting back to four dimensions, to the introduction of four independent electromagnetic charges. In the case where these charges are set pairwise equal, we then generalise the four-dimensional rotating black holes to solutions of gauged N=4 supergravity, with mass, angular momentum and two independent electromagnetic charges. The dilaton and axion fields are non-constant. We also find generalisations of the gauged and ungauged solutions to include the NUT parameter, and for the ungauged solutions, the acceleration parameter too. The solutions in gauged supergravity provide new gravitational backgrounds for a further study of the AdS 4 /CFT 3 correspondence at non-zero temperature

  17. Mass, angular momentum and thermodynamics in four-dimensional Kerr-AdS black holes

    Energy Technology Data Exchange (ETDEWEB)

    Olea, Rodrigo [Departamento de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile)

    2005-06-01

    In this paper, the connection between the Lorentz-covariant counterterms that regularize the four-dimensional AdS gravity action and topological invariants is explored. It is shown that demanding the spacetime to have a negative constant curvature in the asymptotic region permits the explicit construction of such series of boundary terms. The orthonormal frame is adapted to appropriately describe the boundary geometry and, as a result, the boundary term can be expressed as a functional of the boundary metric, extrinsic curvature and intrinsic curvature. This choice also allows to write down the background-independent Noether charges associated to asymptotic symmetries in standard tensorial formalism. The absence of the Gibbons-Hawking term is a consequence of an action principle based on a boundary condition different than Dirichlet on the metric. This argument makes plausible the idea of regarding this approach as an alternative regularization scheme for AdS gravity in all even dimensions, different than the standard counterterms prescription. As an illustration of the finiteness of the charges and the euclidean action in this framework, the conserved quantities and black hole entropy for four-dimensional Kerr-AdS are computed.

  18. Verification of absorbed dose calculation with XIO Radiotherapy Treatment Planning System

    International Nuclear Information System (INIS)

    Bokulic, T.; Budanec, M.; Frobe, A.; Gregov, M.; Kusic, Z.; Mlinaric, M.; Mrcela, I.

    2013-01-01

    Modern radiotherapy relies on computerized treatment planning systems (TPS) for absorbed dose calculation. Most TPS require a detailed model of a given machine and therapy beams. International Atomic Energy Agency (IAEA) recommends acceptance testing for the TPS (IAEA-TECDOC-1540). In this study we present customization of those tests for measurements with the purpose of verification of beam models intended for clinical use in our department. Elekta Synergy S linear accelerator installation and data acquisition for Elekta CMS XiO 4.62 TPS was finished in 2011. After the completion of beam modelling in TPS, tests were conducted in accordance with the IAEA protocol for TPS dose calculation verification. The deviations between the measured and calculated dose were recorded for 854 points and 11 groups of tests in a homogenous phantom. Most of the deviations were within tolerance. Similar to previously published results, results for irregular L shaped field and asymmetric wedged fields were out of tolerance for certain groups of points.(author)

  19. A correlation study on the displacement of the whole breast target after breast-conserving surgery based on four-dimensional computed tomography

    International Nuclear Information System (INIS)

    Wang Wei; Li Jianbin; Wang Suzhen; Zhang Yingjie; Li Fengxiang; Xu Min; Shang Dongping

    2011-01-01

    Objective: To investigate the correlations of the whole breast displacement in different respiratory cycle during free breathing (FB) following breast-conserving surgery to the displacement of selected skin marker, nipple, and selected surgical clip based on four-dimensional computed tomography (4D-CT). Methods: Thirteen breast cancer patients who had undergone breast-conserving surgery received whole breast intensity-modulated radiotherapy (IMRT). Respiration-synchronized 4D-CT image data were gathered during FB and were exported to the Varian Eclipse treatment planning system, and the whole breast target, nipple, superior clip,and metal marker on the skin at the anterior body midline were delineated on the CT images of ten phases of the respiratory cycle by the same radiotherapist based on the same delineating criteria. The displacement distances of the delineated target in the mediolateral (x), anteroposterior (y), and superoinferior (z) axles were achieved,and the correlations of the whole breast target displacement to the displacement of the clip, nipple, and skin marker were analyzed. The ipsilateral lung was delineated on the CT images of every phase of the respiratory cycle, and the changes in ipsilateral lung volume were analyzed during the respiratory cycle relative to the displacement of the breast. Results: The maximal displacement distances of the whole breast target in the x, y, and z axles during FB were 0.71, 0.76 and 1.29 mm, respectively (F=5.755, P<0.05). There was no relationship between the three-dimensional (3D) displacement of the whole breast and the volume of the whole breast (r=-0.264, P<0.05), and there was no relationship between the displacement of the whole breast and the volume change of the ipsilateral lung (r=0.346, P<0.05). There was no significant difference among the mean target displacement distances in 3 axles,and among 2 selected successive end-inspiration (EI) phases and 3 selected successive end-expiration (EE) phases. There

  20. A multi-institutional study to assess adherence to lung stereotactic body radiotherapy planning goals

    Energy Technology Data Exchange (ETDEWEB)

    Woerner, Andrew; Roeske, John C.; Harkenrider, Matthew M.; Campana, Maria; Surucu, Murat, E-mail: msurucu@lumc.edu [Loyola University Medical Center, Maywood, Illinois 60153 (United States); Fan, John [Edward Cancer Center, Naperville, Illinois 60540 (United States); Aydogan, Bulent; Koshy, Matthew [Department of Radiation Oncology, University of Illinois at Chicago, Chicago, Illinois 60612 (United States); Laureckas, Robert; Vali, Faisal [Advocate Christ Medical Center, Oak Lawn, Illinois 60453 (United States)

    2015-08-15

    Purpose: A multi-institutional planning study was performed to evaluate the frequency that current guidelines established by Radiation Therapy Oncology Group (RTOG) protocols and other literature for lung stereotactic body radiotherapy (SBRT) treatments are followed. Methods: A total of 300 patients receiving lung SBRT treatments in four different institutions were retrospectively reviewed. The treatments were delivered using Linac based SBRT (160 patients) or image guided robotic radiosurgery (140). Most tumors were located peripherally (250/300). Median fractional doses and ranges were 18 Gy (8–20 Gy), 12 Gy (6–15 Gy), and 10 Gy (5–12 Gy) for three, four, and five fraction treatments, respectively. The following planning criteria derived from RTOG trials and the literature were used to evaluate the treatment plans: planning target volumes, PTV{sub V} {sub 100} ≥ 95% and PTV{sub V} {sub 95} ≥ 99%; conformality indices, CI{sub 100%} < 1.2 and CI{sub 50%} range of 2.9–5.9 dependent on PTV; total lung-ITV: V{sub 20Gy} < 10%, V{sub 12.5Gy} < 15%, and V{sub 5Gy} < 37%; contralateral lung V{sub 5Gy} < 26%; and maximum doses for spinal cord, esophagus, trachea/bronchus, and heart and great vessels. Populations were grouped by number of fractions, and dosimetric criteria satisfaction rates (CSRs) were reported. Results: Five fraction regimens were the most common lung SBRT fractionation (46%). The median PTV was 27.2 cm{sup 3} (range: 3.8–419.5 cm{sup 3}). For all plans: mean PTV{sub V} {sub 100} was 94.5% (±5.6%, planning CSR: 69.8%), mean PTV{sub V} {sub 95} was 98.1% (±4.1%, CSR: 69.5%), mean CI{sub 100%} was 1.14 (±0.21, CSR: 79.1%, and 16.5% within minor deviation), and mean CI{sub 50%} was 5.63 (±2.8, CSR: 33.0%, and 28.0% within minor deviation). When comparing plans based on location, peripherally located tumors displayed higher PTV{sub V} {sub 100} and PTV{sub V} {sub 95} CSR (71.5% and 71.9%, respectively) than centrally located tumors (61

  1. A multi-institutional study to assess adherence to lung stereotactic body radiotherapy planning goals

    International Nuclear Information System (INIS)

    Woerner, Andrew; Roeske, John C.; Harkenrider, Matthew M.; Campana, Maria; Surucu, Murat; Fan, John; Aydogan, Bulent; Koshy, Matthew; Laureckas, Robert; Vali, Faisal

    2015-01-01

    Purpose: A multi-institutional planning study was performed to evaluate the frequency that current guidelines established by Radiation Therapy Oncology Group (RTOG) protocols and other literature for lung stereotactic body radiotherapy (SBRT) treatments are followed. Methods: A total of 300 patients receiving lung SBRT treatments in four different institutions were retrospectively reviewed. The treatments were delivered using Linac based SBRT (160 patients) or image guided robotic radiosurgery (140). Most tumors were located peripherally (250/300). Median fractional doses and ranges were 18 Gy (8–20 Gy), 12 Gy (6–15 Gy), and 10 Gy (5–12 Gy) for three, four, and five fraction treatments, respectively. The following planning criteria derived from RTOG trials and the literature were used to evaluate the treatment plans: planning target volumes, PTV_V _1_0_0 ≥ 95% and PTV_V _9_5 ≥ 99%; conformality indices, CI_1_0_0_% < 1.2 and CI_5_0_% range of 2.9–5.9 dependent on PTV; total lung-ITV: V_2_0_G_y < 10%, V_1_2_._5_G_y < 15%, and V_5_G_y < 37%; contralateral lung V_5_G_y < 26%; and maximum doses for spinal cord, esophagus, trachea/bronchus, and heart and great vessels. Populations were grouped by number of fractions, and dosimetric criteria satisfaction rates (CSRs) were reported. Results: Five fraction regimens were the most common lung SBRT fractionation (46%). The median PTV was 27.2 cm"3 (range: 3.8–419.5 cm"3). For all plans: mean PTV_V _1_0_0 was 94.5% (±5.6%, planning CSR: 69.8%), mean PTV_V _9_5 was 98.1% (±4.1%, CSR: 69.5%), mean CI_1_0_0_% was 1.14 (±0.21, CSR: 79.1%, and 16.5% within minor deviation), and mean CI_5_0_% was 5.63 (±2.8, CSR: 33.0%, and 28.0% within minor deviation). When comparing plans based on location, peripherally located tumors displayed higher PTV_V _1_0_0 and PTV_V _9_5 CSR (71.5% and 71.9%, respectively) than centrally located tumors (61.2% and 57.1%, respectively). Overall, the planning criteria were met for all the

  2. SU-E-J-137: Incorporating Tumor Regression Into Robust Plan Optimization for Head and Neck Radiotherapy

    International Nuclear Information System (INIS)

    Zhang, P; Hu, J; Tyagi, N; Mageras, G; Lee, N; Hunt, M

    2014-01-01

    Purpose: To develop a robust planning paradigm which incorporates a tumor regression model into the optimization process to ensure tumor coverage in head and neck radiotherapy. Methods: Simulation and weekly MR images were acquired for a group of head and neck patients to characterize tumor regression during radiotherapy. For each patient, the tumor and parotid glands were segmented on the MR images and the weekly changes were formulated with an affine transformation, where morphological shrinkage and positional changes are modeled by a scaling factor, and centroid shifts, respectively. The tumor and parotid contours were also transferred to the planning CT via rigid registration. To perform the robust planning, weekly predicted PTV and parotid structures were created by transforming the corresponding simulation structures according to the weekly affine transformation matrix averaged over patients other than him/herself. Next, robust PTV and parotid structures were generated as the union of the simulation and weekly prediction contours. In the subsequent robust optimization process, attainment of the clinical dose objectives was required for the robust PTV and parotids, as well as other organs at risk (OAR). The resulting robust plans were evaluated by looking at the weekly and total accumulated dose to the actual weekly PTV and parotid structures. The robust plan was compared with the original plan based on the planning CT to determine its potential clinical benefit. Results: For four patients, the average weekly change to tumor volume and position was −4% and 1.2 mm laterally-posteriorly. Due to these temporal changes, the robust plans resulted in an accumulated PTV D95 that was, on average, 2.7 Gy higher than the plan created from the planning CT. OAR doses were similar. Conclusion: Integration of a tumor regression model into target delineation and plan robust optimization is feasible and may yield improved tumor coverage. Part of this research is supported

  3. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Alves, G.G. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Kinoshita, A. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Universidade Sagrado Coração, Bauru, SP (Brazil); Oliveira, H.F. de; Guimarães, F.S.; Amaral, L.L. [Serviço de Radioterapia, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Baffa, O. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

    2015-05-26

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.

  4. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry.

    Science.gov (United States)

    Alves, G G; Kinoshita, A; Oliveira, H F de; Guimarães, F S; Amaral, L L; Baffa, O

    2015-07-01

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.

  5. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

    International Nuclear Information System (INIS)

    Alves, G.G.; Kinoshita, A.; Oliveira, H.F. de; Guimarães, F.S.; Amaral, L.L.; Baffa, O.

    2015-01-01

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses

  6. Operations research for resource planning and -use in radiotherapy: a literature review.

    Science.gov (United States)

    Vieira, Bruno; Hans, Erwin W; van Vliet-Vroegindeweij, Corine; van de Kamer, Jeroen; van Harten, Wim

    2016-11-25

    The delivery of radiotherapy (RT) involves the use of rather expensive resources and multi-disciplinary staff. As the number of cancer patients receiving RT increases, timely delivery becomes increasingly difficult due to the complexities related to, among others, variable patient inflow, complex patient routing, and the joint planning of multiple resources. Operations research (OR) methods have been successfully applied to solve many logistics problems through the development of advanced analytical models for improved decision making. This paper presents the state of the art in the application of OR methods for logistics optimization in RT, at various managerial levels. A literature search was performed in six databases covering several disciplines, from the medical to the technical field. Papers included in the review were published in peer-reviewed journals from 2000 to 2015. Data extraction includes the subject of research, the OR methods used in the study, the extent of implementation according to a six-stage model and the (potential) impact of the results in practice. From the 33 papers included in the review, 18 addressed problems related to patient scheduling (of which 12 focus on scheduling patients on linear accelerators), 8 focus on strategic decision making, 5 on resource capacity planning, and 2 on patient prioritization. Although calculating promising results, none of the papers reported a full implementation of the model with at least a thorough pre-post performance evaluation, indicating that, apart from possible reporting bias, implementation rates of OR models in RT are probably low. The literature on OR applications in RT covers a wide range of approaches from strategic capacity management to operational scheduling levels, and shows that considerable benefits in terms of both waiting times and resource utilization are likely to be achieved. Various fields can be further developed, for instance optimizing the coordination between the available

  7. Recommendations for CTV margins in radiotherapy planning for non melanoma skin cancer.

    Science.gov (United States)

    Khan, Luluel; Choo, Richard; Breen, Dale; Assaad, Dalal; Fialkov, Jefferey; Antonyshyn, Oleh; McKenzie, David; Woo, Tony; Zhang, Liying; Barnes, Elizabeth

    2012-08-01

    To provide practice guidelines for delineating clinical target volume (CTV) for radiotherapy planning of non melanoma (NMSC) skin cancers. A prospective, single arm, study. Preoperatively, a radiation oncologist outlined the boundary of a gross lesion, and drew 5-mm incremental marks in four directions from the delineated border. Under local anesthesia, the lesion was excised, and resection margins were assessed microscopically by frozen section. Once resection margins were clear, the microscopic tumor extent was calculated using the presurgical incremental markings as references. A potential relationship between the distance of microscopic tumor extension and other variables was analyzed. A total of 159 lesions in 150 consecutive patients, selected for surgical excision with frozen section assisted assessment of resection margins, were accrued. The distance of microscopic tumor extension beyond a gross lesion varied from 1mm to 15 mm, with a mean of 5.3mm. The microscopic tumor extent was positively correlated with the size of gross lesion, histology and number of surgical attempts required to obtain a clear margin. To provide a 95% or greater chance of covering microscopic disease we make the following recommendations for CTV margins; 10mm for BCC less than 2 cm, 13 mm for BCC greater than 2 cm, 11 mm for SCC less than 2 cm, and 14 mm for SCC greater than 2 cm. Tumors greater than 2 cm and SCC histology required larger margins to adequately cover the microscopic extent of disease. This information is crucial in radiation planning of NMSC. Clinicians should be cautioned, as these guidelines may not offer optimum treatment for patients with extremely large or small lesions. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  8. Recommendations for CTV margins in radiotherapy planning for non melanoma skin cancer

    International Nuclear Information System (INIS)

    Khan, Luluel; Choo, Richard; Breen, Dale; Assaad, Dalal; Fialkov, Jefferey; Antonyshyn, Oleh; McKenzie, David; Woo, Tony; Zhang Liying; Barnes, Elizabeth

    2012-01-01

    Purpose: To provide practice guidelines for delineating clinical target volume (CTV) for radiotherapy planning of non melanoma (NMSC) skin cancers. Methods and materials: A prospective, single arm, study. Preoperatively, a radiation oncologist outlined the boundary of a gross lesion, and drew 5-mm incremental marks in four directions from the delineated border. Under local anesthesia, the lesion was excised, and resection margins were assessed microscopically by frozen section. Once resection margins were clear, the microscopic tumor extent was calculated using the presurgical incremental markings as references. A potential relationship between the distance of microscopic tumor extension and other variables was analyzed. Results: A total of 159 lesions in 150 consecutive patients, selected for surgical excision with frozen section assisted assessment of resection margins, were accrued. The distance of microscopic tumor extension beyond a gross lesion varied from 1 mm to 15 mm, with a mean of 5.3 mm. The microscopic tumor extent was positively correlated with the size of gross lesion, histology and number of surgical attempts required to obtain a clear margin. To provide a 95% or greater chance of covering microscopic disease we make the following recommendations for CTV margins; 10 mm for BCC less than 2 cm, 13 mm for BCC greater than 2 cm, 11 mm for SCC less than 2 cm, and 14 mm for SCC greater than 2 cm. Conclusions: Tumors greater than 2 cm and SCC histology required larger margins to adequately cover the microscopic extent of disease. This information is crucial in radiation planning of NMSC. Clinicians should be cautioned, as these guidelines may not offer optimum treatment for patients with extremely large or small lesions.

  9. Classification of fibroglandular tissue distribution in the breast based on radiotherapy planning CT

    International Nuclear Information System (INIS)

    Juneja, Prabhjot; Evans, Philip; Windridge, David; Harris, Emma

    2016-01-01

    Accurate segmentation of breast tissues is required for a number of applications such as model based deformable registration in breast radiotherapy. The accuracy of breast tissue segmentation is affected by the spatial distribution (or pattern) of fibroglandular tissue (FT). The goal of this study was to develop and evaluate texture features, determined from planning computed tomography (CT) data, to classify the spatial distribution of FT in the breast. Planning CT data of 23 patients were evaluated in this study. Texture features were derived from the radial glandular fraction (RGF), which described the distribution of FT within three breast regions (posterior, middle, and anterior). Using visual assessment, experts grouped patients according to FT spatial distribution: sparse or non-sparse. Differences in the features between the two groups were investigated using the Wilcoxon rank test. Classification performance of the features was evaluated for a range of support vector machine (SVM) classifiers. Experts found eight patients and 15 patients had sparse and non-sparse spatial distribution of FT, respectively. A large proportion of features (>9 of 13) from the individual breast regions had significant differences (p <0.05) between the sparse and non-sparse group. The features from middle region had most significant differences and gave the highest classification accuracy for all the SVM kernels investigated. Overall, the features from middle breast region achieved highest accuracy (91 %) with the linear SVM kernel. This study found that features based on radial glandular fraction provide a means for discriminating between fibroglandular tissue distributions and could achieve a classification accuracy of 91 %

  10. Dosimetric comparison of intensity-modulated, conformal, and four-field pelvic radiotherapy boost plans for gynecologic cancer: a retrospective planning study

    International Nuclear Information System (INIS)

    Chan, Philip; Yeo, Inhwan; Perkins, Gregory; Fyles, Anthony; Milosevic, Michael

    2006-01-01

    To evaluate intensity-modulated radiation therapy (IMRT) as an alternative to conformal radiotherapy (CRT) or 4-field box boost (4FB) in women with gynecologic malignancies who are unsuitable for brachytherapy for technical or medical reasons. Dosimetric and toxicity information was analyzed for 12 patients with cervical (8), endometrial (2) or vaginal (2) cancer previously treated with external beam pelvic radiotherapy and a CRT boost. Optimized IMRT boost treatment plans were then developed for each of the 12 patients and compared to CRT and 4FB plans. The plans were compared in terms of dose conformality and critical normal tissue avoidance. The median planning target volume (PTV) was 151 cm 3 (range 58–512 cm 3 ). The median overlap of the contoured rectum with the PTV was 15 (1–56) %, and 11 (4–35) % for the bladder. Two of the 12 patients, both with large PTVs and large overlap of the contoured rectum and PTV, developed grade 3 rectal bleeding. The dose conformity was significantly improved with IMRT over CRT and 4FB (p ≤ 0.001 for both). IMRT also yielded an overall improvement in the rectal and bladder dose-volume distributions relative to CRT and 4FB. The volume of rectum that received the highest doses (>66% of the prescription) was reduced by 22% (p < 0.001) with IMRT relative to 4FB, and the bladder volume was reduced by 19% (p < 0.001). This was at the expense of an increase in the volume of these organs receiving doses in the lowest range (<33%). These results indicate that IMRT can improve target coverage and reduce dose to critical structures in gynecologic patients receiving an external beam radiotherapy boost. This dosimetric advantage will be integrated with other patient and treatment-specific factors, particularly internal tumor movement during fractionated radiotherapy, in the context of a future image-guided radiation therapy study

  11. Dosimetric consequences of the shift towards computed tomography guided target definition and planning for breast conserving radiotherapy

    Directory of Open Access Journals (Sweden)

    Korevaar Erik W

    2008-01-01

    Full Text Available Abstract Background The shift from conventional two-dimensional (2D to three-dimensional (3D-conformal target definition and dose-planning seems to have introduced volumetric as well as geometric changes. The purpose of this study was to compare coverage of computed tomography (CT-based breast and boost planning target volumes (PTV, absolute volumes irradiated, and dose delivered to the organs at risk with conventional 2D and 3D-conformal breast conserving radiotherapy. Methods Twenty-five patients with left-sided breast cancer were subject of CT-guided target definition and 3D-conformal dose-planning, and conventionally defined target volumes and treatment plans were reconstructed on the planning CT. Accumulated dose-distributions were calculated for the conventional and 3D-conformal dose-plans, taking into account a prescribed dose of 50 Gy for the breast plans and 16 Gy for the boost plans. Results With conventional treatment plans, CT-based breast and boost PTVs received the intended dose in 78% and 32% of the patients, respectively, and smaller volumes received the prescribed breast and boost doses compared with 3D-conformal dose-planning. The mean lung dose, the volume of the lungs receiving > 20 Gy, the mean heart dose, and volume of the heart receiving > 30 Gy were significantly less with conventional treatment plans. Specific areas within the breast and boost PTVs systematically received a lower than intended dose with conventional treatment plans. Conclusion The shift towards CT-guided target definition and planning as the golden standard for breast conserving radiotherapy has resulted in improved target coverage at the cost of larger irradiated volumes and an increased dose delivered to organs at risk. Tissue is now included into the breast and boost target volumes that was never explicitly defined or included with conventional treatment. Therefore, a coherent definition of the breast and boost target volumes is needed, based on

  12. Dosimetric consequences of the shift towards computed tomography guided target definition and planning for breast conserving radiotherapy

    International Nuclear Information System (INIS)

    Laan, Hans Paul van der; Dolsma, Wil V; Maduro, John H; Korevaar, Erik W; Langendijk, Johannes A

    2008-01-01

    The shift from conventional two-dimensional (2D) to three-dimensional (3D)-conformal target definition and dose-planning seems to have introduced volumetric as well as geometric changes. The purpose of this study was to compare coverage of computed tomography (CT)-based breast and boost planning target volumes (PTV), absolute volumes irradiated, and dose delivered to the organs at risk with conventional 2D and 3D-conformal breast conserving radiotherapy. Twenty-five patients with left-sided breast cancer were subject of CT-guided target definition and 3D-conformal dose-planning, and conventionally defined target volumes and treatment plans were reconstructed on the planning CT. Accumulated dose-distributions were calculated for the conventional and 3D-conformal dose-plans, taking into account a prescribed dose of 50 Gy for the breast plans and 16 Gy for the boost plans. With conventional treatment plans, CT-based breast and boost PTVs received the intended dose in 78% and 32% of the patients, respectively, and smaller volumes received the prescribed breast and boost doses compared with 3D-conformal dose-planning. The mean lung dose, the volume of the lungs receiving > 20 Gy, the mean heart dose, and volume of the heart receiving > 30 Gy were significantly less with conventional treatment plans. Specific areas within the breast and boost PTVs systematically received a lower than intended dose with conventional treatment plans. The shift towards CT-guided target definition and planning as the golden standard for breast conserving radiotherapy has resulted in improved target coverage at the cost of larger irradiated volumes and an increased dose delivered to organs at risk. Tissue is now included into the breast and boost target volumes that was never explicitly defined or included with conventional treatment. Therefore, a coherent definition of the breast and boost target volumes is needed, based on clinical data confirming tumour control probability and normal

  13. 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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  15. Absorbed doses behind bones with MR image-based dose calculations for radiotherapy treatment planning.

    Science.gov (United States)

    Korhonen, Juha; Kapanen, Mika; Keyrilainen, Jani; Seppala, Tiina; Tuomikoski, Laura; Tenhunen, Mikko

    2013-01-01

    Magnetic resonance (MR) images are used increasingly in external radiotherapy target delineation because of their superior soft tissue contrast compared to computed tomography (CT) images. Nevertheless, radiotherapy treatment planning has traditionally been based on the use of CT images, due to the restrictive features of MR images such as lack of electron density information. This research aimed to measure absorbed radiation doses in material behind different bone parts, and to evaluate dose calculation errors in two pseudo-CT images; first, by assuming a single electron density value for the bones, and second, by converting the electron density values inside bones from T(1)∕T(2)∗-weighted MR image intensity values. A dedicated phantom was constructed using fresh deer bones and gelatine. The effect of different bone parts to the absorbed dose behind them was investigated with a single open field at 6 and 15 MV, and measuring clinically detectable dose deviations by an ionization chamber matrix. Dose calculation deviations in a conversion-based pseudo-CT image and in a bulk density pseudo-CT image, where the relative electron density to water for the bones was set as 1.3, were quantified by comparing the calculation results with those obtained in a standard CT image by superposition and Monte Carlo algorithms. The calculations revealed that the applied bulk density pseudo-CT image causes deviations up to 2.7% (6 MV) and 2.0% (15 MV) to the dose behind the examined bones. The corresponding values in the conversion-based pseudo-CT image were 1.3% (6 MV) and 1.0% (15 MV). The examinations illustrated that the representation of the heterogeneous femoral bone (cortex denser compared to core) by using a bulk density for the whole bone causes dose deviations up to 2% both behind the bone edge and the middle part of the bone (diameter bones). This study indicates that the decrease in absorbed dose is not dependent on the bone diameter with all types of bones. Thus

  16. Literature-based recommendations for treatment planning and execution in high-dose radiotherapy for lung cancer

    International Nuclear Information System (INIS)

    Senan, Suresh; De Ruysscher, Dirk; Giraud, Philippe; Mirimanoff, Rene; Budach, Volker

    2004-01-01

    Background and purpose: To review the literature on techniques used in high-dose radiotherapy of lung cancer in order to develop recommendations for clinical practice and for use in research protocols. Patients and methods: A literature search was performed for articles and abstracts that were considered both clinically relevant and practical to use. The relevant information was arbitrarily categorized under the following headings: patient positioning, CT scanning, incorporating tumour mobility, definition of target volumes, radiotherapy planning, treatment delivery, and scoring of response and toxicity. Results: Recommendations were made for each of the above steps from the published literature. Although most of the recommended techniques have yet to be evaluated in multicenter clinical trials, their use in high-dose radiotherapy to the thorax appears to be rational on the basis of current evidence. Conclusions: Recommendations for the clinical implementation of high-dose conformal radiotherapy for lung tumours were identified in the literature. Procedures that are still considered to be investigational were also highlighted

  17. Energy Dependence of Measured CT Numbers on Substituted Materials Used for CT Number Calibration of Radiotherapy Treatment Planning Systems.

    Directory of Open Access Journals (Sweden)

    Reza Mahmoudi

    Full Text Available For accurate dose calculations, it is necessary to provide a correct relationship between the CT numbers and electron density in radiotherapy treatment planning systems (TPSs. The purpose of this study was to investigate the energy dependence of measured CT numbers on substituted materials used for CT number calibration of radiotherapy TPSs and the resulting errors in the treatment planning calculation doses.In this study, we designed a cylindrical water phantom with different materials used as tissue equivalent materials for the simulation of tissues and obtaining the related CT numbers. For evaluating the effect of CT number variations of substituted materials due to energy changing of scanner (kVp on the dose calculation of TPS, the slices of the scanned phantom at three kVp's were imported into the desired TPSs (MIRS and CorePLAN. Dose calculations were performed on two TPSs.The mean absolute percentage differences between the CT numbers of CT scanner and two treatment planning systems for all the samples were 3.22%±2.57% for CorePLAN and 2.88%±2.11% for MIRS. It was also found that the maximum absolute percentage difference between all of the calculated doses from each photon beam of linac (6 and 15 MV at three kVp's was less than 1.2%.The present study revealed that, for the materials with effective low atomic number, the mean CT number increased with increasing energy, which was opposite for the materials with an effective high atomic number. We concluded that the tissue substitute materials had a different behavior in the energy ranges from 80 to 130 kVp. So, it is necessary to consider the energy dependence of the substitute materials used for the measurement or calibration of CT number for radiotherapy treatment planning systems.

  18. The relationship between the bladder volume and optimal treatment planning in definitive radiotherapy for localized prostate cancer

    International Nuclear Information System (INIS)

    Nakamura, Naoki; Sekiguchi, Kenji; Akahane, Keiko; Shikama, Naoto; Takahashi, Osamu; Hama, Yukihiro; Nakagawa, Keiichi

    2012-01-01

    Background and purpose: There is no current consensus regarding the optimal bladder volumes in definitive radiotherapy for localized prostate cancer. The aim of this study was to clarify the relationship between the bladder volume and optimal treatment planning in radiotherapy for localized prostate cancer. Material and methods: Two hundred and forty-three patients underwent definitive radiotherapy with helical tomotherapy for intermediate- and high-risk localized prostate cancer. The prescribed dose defined as 95 % of the planning target volume (PTV) receiving 100 % of the prescription dose was 76 Gy in 38 fractions. The clinical target volume (CTV) was defined as the prostate with a 5-mm margin and 2 cm of the proximal seminal vesicle. The PTV was defined as the CTV with a 5-mm margin. Treatment plans were optimized to satisfy the dose constraints defined by in-house protocols for PTV and organs at risk (rectum wall, bladder wall, sigmoid colon and small intestine). If all dose constraints were satisfied, the plan was defined as an optimal plan (OP). Results: An OP was achieved with 203 patients (84%). Mean bladder volume (± 1 SD) was 266 ml (± 130 ml) among those with an OP and 214 ml (±130 ml) among those without an OP (p = 0.02). Logistic regression analysis also showed that bladder volumes below 150 ml decreased the possibility of achieving an OP. However, the percentage of patients with an OP showed a plateau effect at bladder volumes above 150 ml. Conclusions. Bladder volume is a significant factor affecting OP rates. However, our results suggest that bladder volumes exceeding 150 ml may not help meet planning dose constraints

  19. 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...

  20. MO-H-19A-01: FEATURED PRESENTATION - Treatment Planning Tool for Radiotherapy with Very High-Energy Electron Beams

    International Nuclear Information System (INIS)

    Bazalova, M; Qu, B; Palma, B; Loo, B; Maxim, P; Hynning, E; Hardemark, B

    2014-01-01

    Purpose: To develop a tool for treatment planning optimization for fast radiotherapy delivered with very high-energy electron beams (VHEE) and to compare VHEE plans to state-of-the-art plans for challenging pelvis and H'N cases. Methods: Treatment planning for radiotherapy delivered with VHEE scanning pencil beams was performed by integrating EGSnrc Monte Carlo (MC) dose calculations with spot scanning optimization run in a research version of RayStation. A Matlab GUI for MC beamlet generation was developed, in which treatment parameters such as the pencil beam size and spacing, energy and number of beams can be selected. Treatment planning study for H'N and pelvis cases was performed and the effect of treatment parameters on the delivered dose distributions was evaluated and compared to the clinical treatment plans. The pelvis case with a 691cm3 PTV was treated with 2-arc 15MV VMAT and the H'N case with four PTVs with total volume of 531cm3 was treated with 4-arc 6MV VMAT. Results: Most studied VHEE plans outperformed VMAT plans. The best pelvis 80MeV VHEE plan with 25 beams resulted in 12% body dose sparing and 8% sparing to the bowel and right femur compared to the VMAT plan. The 100MeV plan was superior to the 150MeV plan. Mixing 100 and 150MeV improved dose sparing to the bladder by 7% compared to either plan. Plans with 16 and 36 beams did not significantly affect the dose distributions compared to 25 beam plans. The best H'N 100MeV VHEE plan decreased mean doses to the brainstem, chiasm, and both globes by 10-42% compared to the VMAT plan. Conclusion: The pelvis and H'N cases suggested that sixteen 100MeV beams might be sufficient specifications of a novel VHEE treatment machine. However, optimum machine parameters will be determined with the presented VHEE treatment-planning tool for a large number of clinical cases. BW Loo and P Maxim received research support from RaySearch Laboratories. E Hynning and B Hardemark are employees of

  1. Modification of a three-dimensional treatment planning system for the use of multi-leaf collimators in conformation radiotherapy

    International Nuclear Information System (INIS)

    Boesecke, R.; Becker, G.; Alandt, K.; Pastyr, O.; Doll, J.; Schlegel, W.; Lorenz, W.J.

    1991-01-01

    The multi-leaf collimator of the DKFZ is designed as a low cost add-on device for conventional linear accelerators for radiotherapy. The technical specification of the computer controlled collimator is briefly described . A major limitation in the use of the wide capabilities of multi-leaf collimators in the clinic is still an appropriate treatment planning system. This paper describes treatment planning and dose calculation techniques for multi-leaf collimators and shows examples where the capabilities of the collimators are used extensively. (author). 18 refs.; 8 figs.; 2 tabs

  2. The four-dimensional non-uniform rational B-splines-based cardiac-torso phantom and its application in medical imaging research

    International Nuclear Information System (INIS)

    Li Chongguo; Wu Dake; Lang Jinyi

    2008-01-01

    Simulation skill is playing an increasingly important role in medical imaging research. four-dimensional non-uniform rational B-splines-based cardiac-torso (4D NCAT) phantom is new tool for meoical imaging res catch and when combined with accurate models for the imaging process a wealth of realistic imaging data from subjects of various anatomies. Can be provided 4D NCAT phantoms have bend widely used in medical research such as SPECT, PET, CT and so on. 4D NCAT phantoms have also been used in inverse planning system of intensity modulated radiation therapy. (authors)

  3. Treatment planning comparison of electron arc therapy and photon intensity modulated radiotherapy for Askin's tumor of chest wall

    International Nuclear Information System (INIS)

    Jamema, Swamidas V.; Sharma, Pramod K.; Laskar, Siddhartha; Deshpande, Deepak D.; Shrivastava, Shyam K.

    2007-01-01

    Background and Purpose: A dosimetric study to quantitatively compare radiotherapy treatment plans for Askin's tumor using Electron Arc (EA) vs. photon Intensity Modulated Radiotherapy (IMRT). Materials and methods: Five patients treated with EA were included in this study. Treatment plans were generated for each patient using EA and IMRT. Plans were compared using dose volume histograms (DVH) of the Planning Target Volume (PTV) and Organs at Risk (OAR). Results: IMRT resulted in superior PTV coverage, and homogeneous dose distribution compared to EA. For EA, 92% of the PTV was covered to 85% of the dose compared to IMRT in which 96% was covered to 95% of the dose. V 107 that represents the hot spot within the PTV was more in IMRT compared to EA: 7.4(±2)% vs. 3(±0.5)%, respectively. With PTVs located close to the spinal cord (SC), the dose to SC was more with EA, whereas for PTVs located away from the SC, the dose to SC was more with IMRT. The cardiac dose profile was similar to that of SC. Ipsilateral lung received lower doses with IMRT while contralateral lung received higher dose with IMRT compared to EA. For non-OAR normal tissues, IMRT resulted in large volumes of low dose regions. Conclusions: IMRT resulted in superior PTV coverage and sparing of OAR compared to EA plans. Although IMRT seems to be superior to EA, one needs to keep in mind the volume of low dose regions associated with IMRT, especially while treating young children

  4. Evaluation of the impact of dental artefacts on intensity-modulated radiotherapy planning for the head and neck

    International Nuclear Information System (INIS)

    Webster, Gareth J.; Rowbottom, Carl G.; Mackay, Ranald I.

    2009-01-01

    Background and purpose: High density materials create severe artefacts in the computed tomography (CT) scans used for radiotherapy dose calculations. Increased use of intensity-modulated radiotherapy (IMRT) to treat oropharyngeal cancers raises concerns over the accuracy of the resulting dose calculation. This work quantifies their impact and evaluates a simple corrective technique. Materials and methods: Fifteen oropharyngeal patients with severe artefacts were retrospectively planned with IMRT using two different CT/density look-up tables. Each plan was recalculated using a corrected CT dataset to evaluate the dose distribution delivered to the patient. Plan quality in the absence of dental artefacts was similarly assessed. A range of dosimetric and radiobiological parameters were compared pre- and post-correction. Results: Plans using a standard CT/density look-up table (density ≤1.8 g/cm 3 ) revealed inconsistent inter-patient errors, mostly within clinical acceptance, although potentially significantly reducing target coverage for individual patients. Using an extended CT/density look-up table (density ≤10.0 g/cm 3 ) greatly reduced the errors for 13/15 patients. In 2/15 patients with residual errors the CTV extended into the severely affected region and could be corrected by applying a simple manual correction. Conclusions: Use of an extended CT/density look-up table together with a simple manual bulk density correction reduces the impact of dental artefacts on head and neck IMRT planning to acceptable levels.

  5. Radiotherapy planning for glioblastoma based on a tumor growth model: improving target volume delineation

    Science.gov (United States)

    Unkelbach, Jan; Menze, Bjoern H.; Konukoglu, Ender; Dittmann, Florian; Le, Matthieu; Ayache, Nicholas; Shih, Helen A.

    2014-02-01

    Glioblastoma differ from many other tumors in the sense that they grow infiltratively into the brain tissue instead of forming a solid tumor mass with a defined boundary. Only the part of the tumor with high tumor cell density can be localized through imaging directly. In contrast, brain tissue infiltrated by tumor cells at low density appears normal on current imaging modalities. In current clinical practice, a uniform margin, typically two centimeters, is applied to account for microscopic spread of disease that is not directly assessable through imaging. The current treatment planning procedure can potentially be improved by accounting for the anisotropy of tumor growth, which arises from different factors: anatomical barriers such as the falx cerebri represent boundaries for migrating tumor cells. In addition, tumor cells primarily spread in white matter and infiltrate gray matter at lower rate. We investigate the use of a phenomenological tumor growth model for treatment planning. The model is based on the Fisher-Kolmogorov equation, which formalizes these growth characteristics and estimates the spatial distribution of tumor cells in normal appearing regions of the brain. The target volume for radiotherapy planning can be defined as an isoline of the simulated tumor cell density. This paper analyzes the model with respect to implications for target volume definition and identifies its most critical components. A retrospective study involving ten glioblastoma patients treated at our institution has been performed. To illustrate the main findings of the study, a detailed case study is presented for a glioblastoma located close to the falx. In this situation, the falx represents a boundary for migrating tumor cells, whereas the corpus callosum provides a route for the tumor to spread to the contralateral hemisphere. We further discuss the sensitivity of the model with respect to the input parameters. Correct segmentation of the brain appears to be the most

  6. A hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

    International Nuclear Information System (INIS)

    Lei Yu; Wu Qiuwen

    2010-01-01

    Offline adaptive radiotherapy (ART) has been used to effectively correct and compensate for prostate motion and reduce the required margin. The efficacy depends on the characteristics of the patient setup error and interfraction motion through the whole treatment; specifically, systematic errors are corrected and random errors are compensated for through the margins. In online image-guided radiation therapy (IGRT) of prostate cancer, the translational setup error and inter-fractional prostate motion are corrected through pre-treatment imaging and couch correction at each fraction. However, the rotation and deformation of the target are not corrected and only accounted for with margins in treatment planning. The purpose of this study was to investigate whether the offline ART strategy is necessary for an online IGRT protocol and to evaluate the benefit of the hybrid strategy. First, to investigate the rationale of the hybrid strategy, 592 cone-beam-computed tomography (CBCT) images taken before and after each fraction for an online IGRT protocol from 16 patients were analyzed. Specifically, the characteristics of prostate rotation were analyzed. It was found that there exist systematic inter-fractional prostate rotations, and they are patient specific. These rotations, if not corrected, are persistent through the treatment fraction, and rotations detected in early fractions are representative of those in later fractions. These findings suggest that the offline adaptive replanning strategy is beneficial to the online IGRT protocol with further margin reductions. Second, to quantitatively evaluate the benefit of the hybrid strategy, 412 repeated helical CT scans from 25 patients during the course of treatment were included in the replanning study. Both low-risk patients (LRP, clinical target volume, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles) were included in the simulation. The contours of prostate and seminal vesicles were

  7. Radiotherapy planning for glioblastoma based on a tumor growth model: improving target volume delineation

    International Nuclear Information System (INIS)

    Unkelbach, Jan; Dittmann, Florian; Le, Matthieu; Shih, Helen A; Menze, Bjoern H; Ayache, Nicholas; Konukoglu, Ender

    2014-01-01

    Glioblastoma differ from many other tumors in the sense that they grow infiltratively into the brain tissue instead of forming a solid tumor mass with a defined boundary. Only the part of the tumor with high tumor cell density can be localized through imaging directly. In contrast, brain tissue infiltrated by tumor cells at low density appears normal on current imaging modalities. In current clinical practice, a uniform margin, typically two centimeters, is applied to account for microscopic spread of disease that is not directly assessable through imaging. The current treatment planning procedure can potentially be improved by accounting for the anisotropy of tumor growth, which arises from different factors: anatomical barriers such as the falx cerebri represent boundaries for migrating tumor cells. In addition, tumor cells primarily spread in white matter and infiltrate gray matter at lower rate. We investigate the use of a phenomenological tumor growth model for treatment planning. The model is based on the Fisher–Kolmogorov equation, which formalizes these growth characteristics and estimates the spatial distribution of tumor cells in normal appearing regions of the brain. The target volume for radiotherapy planning can be defined as an isoline of the simulated tumor cell density. This paper analyzes the model with respect to implications for target volume definition and identifies its most critical components. A retrospective study involving ten glioblastoma patients treated at our institution has been performed. To illustrate the main findings of the study, a detailed case study is presented for a glioblastoma located close to the falx. In this situation, the falx represents a boundary for migrating tumor cells, whereas the corpus callosum provides a route for the tumor to spread to the contralateral hemisphere. We further discuss the sensitivity of the model with respect to the input parameters. Correct segmentation of the brain appears to be the most

  8. Parotid Gland Dose in Intensity-Modulated