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https://www.readbyqxmd.com/read/28300378/comparison-of-linear-and-nonlinear-programming-approaches-for-worst-case-dose-and-minmax-robust-optimization-of-intensity-modulated-proton-therapy-dose-distributions
#1
Maryam Zaghian, Wenhua Cao, Wei Liu, Laleh Kardar, Sharmalee Randeniya, Radhe Mohan, Gino Lim
Robust optimization of intensity-modulated proton therapy (IMPT) takes uncertainties into account during spot weight optimization and leads to dose distributions that are resilient to uncertainties. Previous studies demonstrated benefits of linear programming (LP) for IMPT in terms of delivery efficiency by considerably reducing the number of spots required for the same quality of plans. However, a reduction in the number of spots may lead to loss of robustness. The purpose of this study was to evaluate and compare the performance in terms of plan quality and robustness of two robust optimization approaches using LP and nonlinear programming (NLP) models...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28281862/model-based-approach-for-quantitative-estimates-of-skin-heart-and-lung-toxicity-risk-for-left-side-photon-and-proton-irradiation-after-breast-conserving-surgery
#2
Francesco Tommasino, Marco Durante, Vittoria D'Avino, Raffaele Liuzzi, Manuel Conson, Paolo Farace, Giuseppe Palma, Marco Schwarz, Laura Cella, Roberto Pacelli
BACKGROUND: Proton beam therapy represents a promising modality for left-side breast cancer (BC) treatment, but concerns have been raised about skin toxicity and poor cosmesis. The aim of this study is to apply skin normal tissue complication probability (NTCP) model for intensity modulated proton therapy (IMPT) optimization in left-side BC. MATERIAL AND METHODS: Ten left-side BC patients undergoing photon irradiation after breast-conserving surgery were randomly selected from our clinical database...
March 10, 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28140380/near-real-time-automated-dose-restoration-in-impt-to-compensate-for-daily-tissue-density-variations-in-prostate-cancer
#3
Thyrza Zeralda Jagt, Sebastiaan Breedveld, Steven van de Water, Ben Heijmen, Mischa Hoogeman
Proton therapy is very sensitive to daily density changes along the pencil beam paths. The purpose of this study is to develop and evaluate an automated method for adaptation of IMPT plans to compensate for these daily tissue density variations. A two-step restoration method for ���densities-of-the-day��� was created: (1) restoration of spot positions (Bragg peaks) by adapting the energy of each pencil beam to the new water equivalent path length; and (2) re-optimization of pencil beam weights by minimizing the dosimetric difference with the planned dose distribution, using a fast and exact quadratic solver...
January 31, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28114107/generation-of-synthetic-ct-data-using-patient-specific-daily-mr-image-data-and-image-registration
#4
Kim Melanie Kraus, Oliver Jäkel, Nina I Niebuhr, Asja Pfaffenberger
To fully exploit the advantages of magnetic resonance imaging (MRI) for radiotherapy (RT) treatment planning, a method is required to overcome the problem of lacking electron density information. We aim to establish and evaluate a new method for computed tomography (CT) data generation based on MRI and image registration. The thereby generated CT data is used for dose accumulation. We developed a process flow based on an initial pair of rigidly co-registered CT and T2-weighted MR image representing the same anatomical situation...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28077128/treatment-planning-comparison-of-impt-vmat-and-4%C3%AF-radiotherapy-for-prostate-cases
#5
Angelia Tran, Jingjing Zhang, Kaley Woods, Victoria Yu, Dan Nguyen, Gary Gustafson, Lane Rosen, Ke Sheng
BACKGROUND: Intensity-modulated proton therapy (IMPT), non-coplanar 4π intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) represent the most advanced treatment methods based on heavy ion and X-rays, respectively. Here we compare their performance for prostate cancer treatment. METHODS: Ten prostate patients were planned using IMPT with robustness optimization, VMAT, and 4π to an initial dose of 54 Gy to a clinical target volume (CTV) that encompassed the prostate and seminal vesicles, then a boost prescription dose of 25...
January 11, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28048824/su-f-t-123-the-simulated-effect-of-the-breath-hold-reproducibility-treating-locally-advanced-lung-cancer-with-pencil-beam-scanned-proton-therapy
#6
J Dueck, R Perrin, G F Persson, A Lomax, M Josipovic, S A Engelholm, D C Weber, P Munck, A F Rosenschöld
PURPOSE: The breath-hold (BH) technique has been suggested to mitigate motion and reduce target coverage degradation due to motion effects. The aim of this study was to investigate the effect of inter-BH residual motion on the dose distribution for pencil beam scanned (PBS) proton therapy of locally-advanced lung cancer patients. METHODS: A dataset of visually-guided BH CT scans was acquired (10 scans per patient) taken from five lung cancer patients: three intra-fractionally repeated CT scans on treatment days 2,16 and 31, in addition to the day 0 planning CT scan...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048742/su-f-t-192-study-of-robustness-analysis-method-of-multiple-field-optimized-impt-plans-for-head-neck-patients
#7
Y Li, X Wang, H Li, J Wang, X Zhu, Y Li, S Frank, X Zhang
PURPOSE: Proton therapy is more sensitive to uncertainties than photon treatments due to protons' finite range depending on the tissue density. Worst case scenario (WCS) method originally proposed by Lomax has been adopted in our institute for robustness analysis of IMPT plans. This work demonstrates that WCS method is sufficient enough to take into account of the uncertainties which could be encountered during daily clinical treatment. METHODS: A fast and approximate dose calculation method is developed to calculate the dose for the IMPT plan under different setup and range uncertainties...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048730/su-f-t-148-are-the-approximations-in-analytic-semi-empirical-dose-calculation-algorithms-for-intensity-modulated-proton-therapy-for-complex-heterogeneities-of-head-and-neck-clinically-significant
#8
P Yepes, U Titt, D Mirkovic, A Liu, S Frank, R Mohan
PURPOSE: Evaluate the differences in dose distributions between the proton analytic semi-empirical dose calculation algorithm used in the clinic and Monte Carlo calculations for a sample of 50 head-and-neck (H&N) patients and estimate the potential clinical significance of the differences. METHODS: A cohort of 50 H&N patients, treated at the University of Texas Cancer Center with Intensity Modulated Proton Therapy (IMPT), were selected for evaluation of clinical significance of approximations in computed dose distributions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048674/su-f-t-215-an-investigation-of-multi-scanner-ct-hounsfield-unit-calibration-for-pencil-beam-scanning-proton-therapy-using-3d-gamma-analysis
#9
J Zhang, X Li, G Liu, Q Liu, J Liang, X Ding
PURPOSE: We compare and investigate the dosimetric impacts on pencil beam scanning (PBS) proton treatment plans generated with CT calibration curves from four different CT scanners and one averaged 'global' CT calibration curve. METHODS: The four CT scanners are located at three different hospital locations within the same health system. CT density calibration curves were collected from these scanners using the same CT calibration phantom and acquisition parameters...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048650/su-f-t-195-systematic-constraining-of-contralateral-parotid-gland-led-to-improved-dosimetric-outcomes-for-multi-field-optimization-with-scanning-beam-proton-therapy-promising-results-from-a-pilot-study-in-patients-with-base-of-tongue-carcinoma
#10
R Wu, C Crowford, R Georges, A Liu, M Amin, T Sio, B Gunn, F Poenisch, M Palmer, M Gillin, S Frank, X Zhu
PURPOSE: Treatment planning for Intensity Modulated Proton Therapy (IMPT) for head and neck cancer is time-consuming due to the large number of organs-at-risk (OAR) to be considered. As there are many competing objectives and also wide range of acceptable OAR constraints, the final approved plan may not be most optimal for the given structures. We evaluated the dose reduction to the contralateral parotid by implementing standardized constraints during optimization for scanning beam proton therapy planning...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048518/th-cd-209-05-impact-of-spot-size-and-spacing-on-the-quality-of-robustly-optimized-intensity-modulated-proton-therapy-plans-for-lung-cancer
#11
W Liu, S Schild, J Chang, Z Liao, X Ding, Y Hu, J Shen, S Korte, N Sahoo, W Wong, M Herman, M Bues
PURPOSE: To investigate how spot size and spacing affect plan quality, especially, plan robustness and the impact of interplay effect, of robustly-optimized intensity-modulated proton therapy (IMPT) plans for lung cancer. METHODS: Two robustly-optimized IMPT plans were created for 10 lung cancer patients: (1) one for a proton beam with in-air energy dependent large spot size at isocenter (σ: 5-15 mm) and spacing (1.53σ); (2) the other for a proton beam with small spot size (σ: 2-6 mm) and spacing (5 mm)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048379/su-f-t-598-robotic-radiosurgery-system-versus-pencil-beam-scanning-proton-therapy-for-definitive-intracranial-treatments
#12
M Lin, A Pompos, X Gu, Y Yan, R Abdulrahman, R Timmerman, S Jiang
PURPOSE: To characterize the dose distributions of Cyberknife and intensity-modulated-proton-therapy (IMPT). METHODS: A total of 20 patients previously treated with Cyberknife were selected. The original planning-target-volume (PTV) was used in the 'IMPT-ideal' plan assuming a comparable image-guidance with Cyberknife. A 3mm expansion was made to create the proton-PTV for the 'IMPT-3mm' plan representing the current proton-therapy where a margin of 3mm is used to account for the inferior image-guidance...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048238/su-g-tep1-06-fast-gpu-framework-for-four-dimensional-monte-carlo-in-adaptive-intensity-modulated-proton-therapy-impt-for-mobile-tumors
#13
P Botas, C Grassberger, G Sharp, N Qin, X Jia, S Jiang, H Paganetti
PURPOSE: To demonstrate the feasibility of fast Monte Carlo (MC) treatment planning and verification using four-dimensional CT (4DCT) for adaptive IMPT for lung cancer patients. METHODS: A validated GPU MC code, gPMC, has been linked to the patient database at our institution and employed to compute the dose-influence matrices (Dij) on the planning CT (pCT). The pCT is an average of the respiratory motion of the patient. The Dijs and patient structures were fed to the optimizer to calculate a treatment plan...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048222/su-f-j-186-enabling-adaptive-impt-with-cbct-based-dose-recalculation-for-h-n-and-prostate-cancer-patients
#14
C Kurz, Y Park, F Kamp, S Rit, B Winey, G Sharp, M Reiner, R Nijhuis, D Hansen, U Ganswindt, C Thieke, C Belka, K Parodi, G Landry
PURPOSE: To enable adaptive intensity modulated proton therapy for sites sensitive to inter-fractional changes on the basis of accurate CBCT-based proton dose calculations. To this aim two CBCT intensity correction methods are considered: planning CT (pCT) to CBCT DIR and projection correction based on pCT DIR prior. METHODS: 3 H&N and 3 prostate cancer patients with CBCT images and corresponding projections were used in this study, in addition to pCT and re-planning CT (rpCT) images (H&N only)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048086/su-f-t-120-how-many-and-which-respiratory-phases-should-be-included-during-the-4d-robust-optimization-process
#15
S Ge, X Wang, R Mohan
PURPOSE: To study how many and which respiratory phases should be included to conduct an efficient 4D robust optimization since contouring CTV and critical organs at all 10 phases are time consuming. METHODS: A 4D robust optimization algorithm which simultaneously optimizes dose distributions for all 10 respiratory phases has been developed to desensitize plan quality to various uncertainties. To study the possibility of reducing number of phases included during the optimization process while keep the plan quality, four strategies have been conducted and compared: A...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048024/su-f-t-116-predicting-iq-and-the-risk-of-hearing-loss-following-proton-versus-photon-radiotherapy-for-pediatric-brain-tumor-patients
#16
D Fortin, A Ng, D Tsang, M Sharpe, N Laperriere, D Hodgson
PURPOSE: The increased sparing of normal tissues in intensity modulated proton therapy (IMPT) compared to photon intensity modulated radiotherapy (IMRT) in brain tumor treatments should translate into improved neurocognitive outcomes. Models were used to estimate the intelligence quotient (IQ) and the risk of hearing loss 5 years post radiotherapy and to compare outcomes of proton against photon in pediatric brain tumors. METHODS: Patients who had received radical IMRT were randomly selected from our retrospective database: 10 cases each of craniopharyngioma, ependymoma and medulloblastoma, and 20 cases of glioma...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048022/su-f-t-189-dosimetric-comparison-of-spot-scanning-proton-therapy-techniques-for-liver-tumors-close-to-the-skin-surface
#17
S Takao, T Matsuura, Y Matsuzaki, Y Fujii, T Fujii, N Katoh, S Shimizu, K Umegaki, H Shirato
PURPOSE: Spot-scanning technique has been utilized to achieve conformal dose distribution to large and complicated tumors. This technique generally does not require patient-specific devices such as aperture and compensator. The commercially available spot-scanning proton therapy (SSPT) systems, however, cannot deliver proton beams to the region shallower than 4 g/cm2. Therefore some range compensation device is required to treat superficial tumors with SSPT. This study shows dosimetric comparison of the following treatment techniques: (i) with a tabletop bolus, (ii) with a nozzle-mounted applicator, and (iii) without any devices and using intensity-modulated proton therapy (IMPT) technique...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047983/su-f-t-196-hypo-fractionation-with-intensity-modulated-proton-therapy-for-unilateral-metallic-prosthesis-prostate-cancer-patients
#18
S Rana, Y Zheng, Y Zhang, Pokharel, C Cheng, S Park
PURPOSE: The purpose of this study is to investigate the dosimetric feasibility of hypo-fractionated intensity modulated proton therapy (IMPT) for unilateral metallic prosthesis prostate cancer patients based on proton collaborative group (PCG)-GU002-10 (NCT01230866) protocol criteria. METHODS: A total of five unilateral metallic prosthesis prostate cancer cases were included in this retrospective study. For each case, IMPT plans were generated for treatment to be delivered with 7...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047948/su-f-t-203-high-dose-definitive-proton-therapy-with-integrated-boost-to-hypoxic-subvolumes-determined-by-18f-fluoromisonidazole-fmiso-pet-ct-for-patients-with-recurrent-chordomas-using-intensity-modulated-proton-therapy-impt
#19
S Yan, G Broussard, K De, Amorim Bernstein, Y Wang
PURPOSE: Recurrent chordomas are difficult to control locally. This dosimetric study investigates the feasibility of dose escalation to hypoxic regions, visualized on FMISO-PET, while respecting the dose constraints to the neighboring normal tissues/organs. We propose to deliver a higher dose to the areas of hypoxia (84.5Gy) using IMPT with the goal of improving local control. METHODS: We currently have four patients with hypoxic subvolumes (HSV) greater than 10cc from the FMISO-PET image...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047574/th-cd-209-10-scanning-proton-arc-therapy-sparc-the-first-robust-and-delivery-efficient-spot-scanning-proton-arc-therapy
#20
X Ding, X Li, J Zhang, P Kabolizadeh, C Stevens, D Yan
PURPOSE: To develop a delivery-efficient proton spot-scanning arc therapy technique with robust plan quality. METHODS: We developed a Scanning Proton Arc(SPArc) optimization algorithm integrated with (1)Control point re-sampling by splitting control point into adjacent sub-control points; (2)Energy layer re-distribution by assigning the original energy layers to the new sub-control points; (3)Energy layer filtration by deleting low MU weighting energy layers; (4)Energy layer re-sampling by sampling additional layers to ensure the optimal solution...
June 2016: Medical Physics
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