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https://www.readbyqxmd.com/read/28341315/initial-clinical-experience-of-postmastectomy-intensity-modulated-proton-therapy-in-patients-with-breast-expanders-with-metallic-ports
#1
Robert W Mutter, Nicholas B Remmes, Mohamed Mh Kahila, Kathy A Hoeft, Deanna H Pafundi, Yan Zhang, Kimberly S Corbin, Sean S Park, Elizabeth S Yan, Valerie Lemaine, Judy C Boughey, Chris J Beltran
PURPOSE: The feasibility of proton postmastectomy radiation therapy in patients reconstructed with expanders has not been previously reported, limiting treatment options. We analyzed the dosimetric impact of the metallic port contained within expanders on intensity modulated proton therapy (IMPT) and report our techniques and quality control for treating patients in this setting. METHODS AND MATERIALS: Twelve patients with the same expander model underwent 2-field IMPT as part of a prospective registry...
December 16, 2016: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28341297/geant4-models-for-the-secondary-radiation-flux-in-the-collimation-system-of-a-300mev-proton-microbeam
#2
Yanxin Dou, David N Jamieson, Jianli Liu, Anlong Li, Liyi Li
In Harbin, we are developing a 300MeV proton microbeam for many applications in space science including upset studies in microelectronic devices, radiation hardness of materials for satellites and radiation effects in human tissues. There are also applications of this facility proposed for proton therapy. The microbeam system will employ a purpose-built proton synchrotron to provide the beam. However there are many challenges to be addressed in the design, construction and operation of this facility. Here we address two important design aspects for which we apply GEANT4 modeling...
December 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/28332994/predicting-patient-specific-dosimetric-benefits-of-proton-therapy-for-skull-base-tumors-using-a-geometric-knowledge-based-method
#3
David C Hall, Alexei V Trofimov, Brian A Winey, Norbert J Liebsch, Harald Paganetti
PURPOSE: To predict the organ at risk (OAR) dose levels achievable with proton beam therapy (PBT), solely based on the geometric arrangement of the target volume in relation to the OARs. A comparison with an alternative therapy yields a prediction of the patient-specific benefits offered by PBT. This could enable physicians at hospitals without proton capabilities to make a better-informed referral decision or aid patient selection in model-based clinical trials. METHODS AND MATERIALS: Skull-base tumors were chosen to test the method, owing to their geometric complexity and multitude of nearby OARs...
April 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28321635/relative-biological-effectiveness-in-a-proton-spread-out-bragg-peak-formed-by-pencil-beam-scanning-mode
#4
Anna Michaelidesová, Jana Vachelová, Monika Puchalska, Kateřina Pachnerová Brabcová, Vladimír Vondráček, Lembit Sihver, Marie Davídková
In recent years, there is an increased interest in using scanning modes in proton therapy, due to the more conformal dose distributions, thanks to the spot-weighted dose delivery. The dose rate in each spot is however much higher than the dose rate when using passive irradiation modes, which could affect the cell response. The purpose of this work was to investigate how the relative biological effectiveness changes along the spread-out Bragg peak created by protons delivered by the pencil beam scanning mode...
March 20, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28318880/highly-conformal-craniospinal-radiotherapy-techniques-can-underdose-the-cranial-clinical-target-volume-if-leptomeningeal-extension-through-skull-base-exit-foramina-is-not-contoured
#5
D J Noble, T Ajithkumar, J Lambert, I Gleeson, M V Williams, S J Jefferies
AIMS: Craniospinal irradiation (CSI) remains a crucial treatment for patients with medulloblastoma. There is uncertainty about how to manage meningeal surfaces and cerebrospinal fluid (CSF) that follows cranial nerves exiting skull base foramina. The purpose of this study was to assess plan quality and dose coverage of posterior cranial fossa foramina with both photon and proton therapy. MATERIALS AND METHODS: We analysed the radiotherapy plans of seven patients treated with CSI for medulloblastoma and primitive neuro-ectodermal tumours and three with ependymoma (total n = 10)...
March 15, 2017: Clinical Oncology: a Journal of the Royal College of Radiologists
https://www.readbyqxmd.com/read/28300385/a-benchmarking-method-to-evaluate-the-accuracy-of-a-commercial-proton-monte-carlo-pencil-beam-scanning-treatment-planning-system
#6
Liyong Lin, Sheng Huang, Minglei Kang, Petri Hiltunen, Reynald Vanderstraeten, Jari Lindberg, Sami Siljamaki, Todd Wareing, Ian Davis, Allen Barnett, John McGhee, Charles B Simone, Timothy D Solberg, James E McDonough, Christopher Ainsley
AcurosPT is a Monte Carlo algorithm in the Eclipse 13.7 treatment planning system, which is designed to provide rapid and accurate dose calculations for proton therapy. Computational run-time in minimized by simplifying or eliminating less significant physics processes. In this article, the accuracy of AcurosPT was benchmarked against both measurement and an independent MC calculation, TOPAS. Such a method can be applied to any new MC calculation for the detection of potential inaccuracies. To validate multiple Coulomb scattering (MCS) which affects primary beam broadening, single spot profiles in a Solidwater(®) phantom were compared for beams of five selected proton energies between AcurosPT, measurement and TOPAS...
March 2017: Journal of Applied Clinical Medical Physics
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
#7
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/28300377/a-comparison-between-hydrogel-spacer-and-endorectal-balloon-an-analysis-of-intrafraction-prostate-motion-during-proton-therapy
#8
Samantha G Hedrick, Marcio Fagundes, Ben Robison, Marc Blakey, Jackson Renegar, Mark Artz, Niek Schreuder
The purpose of this study was to evaluate intrafraction prostate motion in patients treated with proton therapy and an endorectal balloon or a hydrogel spacer using orthogonal x-rays acquired before and after each treatment field. This study evaluated 10 patients (662 fields throughout treatment) treated daily with an endorectal balloon (ERB) and 16 patients (840 fields throughout treatment) treated with a hydrogel spacer (GEL) without an ERB. Patient shifts were recorded before and after each treatment field, correlated with a treatment time, using x-ray imaging and implanted fiducial alignment...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28299759/optimizing-the-benefit-of-cns-radiation-therapy-in-the-pediatric-population-part-2-novel-methods-of-radiation-delivery
#9
REVIEW
Lindsay S Rowe, Andra V Krauze, Holly Ning, Kevin A Camphausen, Aradhana Kaushal
Newer approaches in the field of radiation therapy have raised the bar in the treatment of central nervous system (CNS) malignancies, with recognized advances that have aimed to increase the therapeutic index by improving conformality of the radiation dose to the planned target volume. Beyond these advances, the continued evolution of more effective systems for delivery of radiation to the CNS may offer further benefit not only to adults but also to pediatric patients, a cohort of the population that may be more sensitive to the long-term effects of radiation...
March 15, 2017: Oncology (Williston Park, NY)
https://www.readbyqxmd.com/read/28297453/spot-scanning-proton-therapy-minimizes-neutron-dose-in-the-setting-of-radiation-therapy-administered-during-pregnancy
#10
Xin Wang, Falk Poenisch, Narayan Sahoo, Ronald X Zhu, MingFwu Lii, Michael T Gillin, Jing Li, David Grosshans
This is a real case study to minimize the neutron dose equivalent (H) to a fetus using spot scanning proton beams with favorable beam energies and angles. Minimum neutron dose exposure to the fetus was achieved with iterative planning under the guidance of neutron H measurement. Two highly conformal treatment plans, each with three spot scanning beams, were planned to treat a 25-year-old pregnant female with aggressive recurrent chordoma of the base of skull who elected not to proceed with termination. Each plan was scheduled for delivery every other day for robust target coverage...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28295434/the-potential-of-dual-energy-ct-to-reduce-proton-beam-range-uncertainties
#11
Esther Bär, Arthur Lalonde, Gary Royle, Hsiao-Ming Lu, Hugo Bouchard
PURPOSE: Dual-energy CT (DECT) promises improvements in estimating stopping power ratios (SPRs) for proton therapy treatment planning. Although several comparable mathematical formalisms have been proposed in literature, the optimal techniques to characterize human tissue SPRs with DECT in a clinical environment are not fully established. The aim of this work is to compare the most robust DECT methods against conventional single-energy CT (SECT) in conditions reproducing a clinical environment, where CT artifacts and noise play a major role on the accuracy of these techniques...
March 15, 2017: Medical Physics
https://www.readbyqxmd.com/read/28295379/a-phenomenological-biological-dose-model-for-proton-therapy-based-on-linear-energy-transfer-spectra
#12
Eivind Rørvik, Sara Thörnqvist, Camilla H Stokkevåg, Tordis J Dahle, Lars Fredrik Fjaera, Kristian S Ytre-Hauge
PURPOSE: The relative biological effectiveness (RBE) of protons varies with the radiation quality, quantified by the linear energy transfer (LET). Most phenomenological models employ a linear dependency of the dose-averaged LET (LETd ) to calculate the biological dose. However, several experiments have indicated a possible non-linear trend. Our aim was to investigate if biological dose models including non-linear LET dependencies should be considered, by introducing a LET spectrum based dose model...
March 15, 2017: Medical Physics
https://www.readbyqxmd.com/read/28294362/systematic-out-of-field-secondary-neutron-spectrometry-and-dosimetry-in-pencil-beam-scanning-proton-therapy
#13
Sebastian Trinkl, Vladimir Mares, Franz Siegfried Englbrecht, Jan Jakob Wilkens, Marek Wielunski, Katia Parodi, Werner Rühm, Martin Hillbrand
BACKGROUND AND PURPOSE: Systematic investigation of the energy and angular dependence of secondary neutron fluence energy distributions and ambient dose equivalents values (H*(10)) inside a pencil beam scanning proton therapy treatment room using a gantry. MATERIAL AND METHODS: Neutron fluence energy distributions were measured with an extended-range Bonner sphere spectrometer featuring ³He proportional counters, at four positions at 0°, 45°, 90° and 135° with respect to beam direction and at a distance of 2 m from the isocenter...
March 11, 2017: Medical Physics
https://www.readbyqxmd.com/read/28291933/validation-of-rectal-sparing-throughout-the-course-of-proton-therapy-treatment-in-prostate-cancer-patients-treated-with-spaceoar-%C3%A2
#14
Samantha G Hedrick, Marcio Fagundes, Sara Case, Jackson Renegar, Marc Blakey, Mark Artz, Hao Chen, Ben Robison, Niek Schreuder
The purpose of this study was to investigate the consistency of rectal sparing using multiple periodic quality assurance computerized tomography imaging scans (QACT) obtained during the course of proton therapy for patients with prostate cancer treated with a hydrogel spacer. Forty-one low- and intermediate-risk prostate cancer patients treated with image-guided proton therapy with rectal spacer hydrogel were analyzed. To assess the reproducibility of rectal sparing with the hydrogel spacer, three to four QACTs were performed for each patient on day 1 and during weeks 1, 3, and 5 of treatment...
January 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28291917/rectal-dose-to-prostate-cancer-patients-treated-with-proton-therapy-with-or-without-rectal-spacer
#15
Heeteak Chung, Jerimy Polf, Shahed Badiyan, Matthew Biagioli, Daniel Fernandez, Kujtim Latifi, Richard Wilder, Minesh Mehta, Michael Chuong
The purpose of this study was to evaluate whether a spacer inserted in the prerectal space could reduce modeled rectal dose and toxicity rates for patients with prostate cancer treated in silico with pencil beam scanning (PBS) proton therapy. A total of 20 patients were included in this study who received photon therapy (12 with rectal spacer (DuraSeal™ gel) and 8 without). Two PBS treatment plans were retrospectively created for each patient using the following beam arrangements: (1) lateral-opposed (LAT) fields and (2) left and right anterior oblique (LAO/RAO) fields...
January 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28283192/supine-craniospinal-irradiation-in-pediatric-patients-by-proton-pencil-beam-scanning
#16
Paolo Farace, Nicola Bizzocchi, Roberto Righetto, Francesco Fellin, Francesco Fracchiolla, Stefano Lorentini, Lamberto Widesott, Carlo Algranati, Barbara Rombi, Sabina Vennarini, Maurizio Amichetti, Marco Schwarz
BACKGROUND AND PURPOSE: Proton therapy is the emerging treatment modality for craniospinal irradiation (CSI) in pediatric patients. Herein, special methods adopted for CSI at proton Therapy Center of Trento by pencil beam scanning (PBS) are comprehensively described. MATERIALS AND METHODS: Twelve pediatric patients were treated by proton PBS using two/three isocenters. Special methods refer to: (i) patient positioning in supine position on immobilization devices crossed by the beams; (ii) planning field-junctions via the ancillary-beam technique; (iii) achieving lens-sparing by three-beams whole-brain-irradiation; (iv) applying a movable-snout and beam-splitting technique to reduce the lateral penumbra...
March 7, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
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
#17
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/28281357/comparison-of-gastric-cancer-radiotherapy-performed-with-volumetric-modulated-arc-therapy-or-single-field-uniform-dose-proton-therapy
#18
Gracinda Mondlane, Michael Gubanski, Pehr A Lind, Ana Ureba, Albert Siegbahn
BACKGROUND: Proton-beam therapy of large abdominal cancers has been questioned due to the large variations in tissue density in the abdomen. The aim of this study was to evaluate the importance of these variations for the dose distributions produced in adjuvant radiotherapy of gastric cancer (GC), implemented with photon-based volumetric modulated arc therapy (VMAT) or with proton-beam single-field uniform-dose (SFUD) method. MATERIAL AND METHODS: Eight GC patients were included in this study...
March 10, 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28258888/using-proton-beam-therapy-in-the-elderly-population-a-snapshot-of-current-perception-and-practice
#19
Juliette Thariat, Terence Sio, Pierre Blanchard, Samir Patel, Yusuke Demizu, Federico Ampil, Sebastien Guihard, Robert C Miller, Ulf Karlsson, Marco Krengli, Huan Giap, Nam Nguyen
PURPOSE: With limited proton therapy (PT) resources, several centers have designed their own decision-making systems for PT slot prioritization. The pediatric population is well recognized for deriving benefits from PT; however, elderly patients are not a focus for PT. When should PT be considered for use in the elderly population? METHODS AND MATERIALS: We performed a pilot survey of 25 international academic radiation oncologists (ROs) who also spend significant amounts of clinical time caring for elderly patients...
January 6, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28252445/comparing-the-dosimetric-impact-of-interfractional-anatomical-changes-in-photon-proton-and-carbon-ion-radiotherapy-for-pancreatic-cancer-patients
#20
Antonetta C Houweling, Koen Crama, Jorrit Visser, Kyohei Fukata, Coen R N Rasch, Tatsuya Ohno, Arjan Bel, Astrid van der Horst
Radiotherapy using charged particles is characterized by a low dose to the surrounding healthy organs, while delivering a high dose to the tumor. However, interfractional anatomical changes can greatly affect the robustness of particle therapy. Therefore, we compared the dosimetric impact of interfractional anatomical changes (i.e. body contour differences and gastrointestinal gas volume changes) in photon, proton and carbon ion therapy for pancreatic cancer patients. In this retrospective planning study, photon, proton and carbon ion treatment plans were created for 9 patients...
April 21, 2017: Physics in Medicine and Biology
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