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https://www.readbyqxmd.com/read/28444840/topas-simulation-of-the-mevion-s250-compact-proton-therapy-unit
#1
Michael Prusator, Salahuddin Ahmad, Yong Chen
As proton therapy becomes increasingly popular, so does the need for Monte Carlo simulation studies involving accurate beam line modeling of proton treatment units. In this study, the 24 beam configurations of the Mevion S250 proton therapy system installed recently at our institution were modeled using the TOolkit for PArticle Simulation (TOPAS) code. Pristine Bragg peak, spread out Bragg peak (SOBP), and lateral beam profile dose distributions were simulated and matched to the measurements taken during commissioning of the unit...
April 26, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28444374/measurement-of-neutron-ambient-dose-equivalent-in-proton-radiotherapy-with-line-scanning-and-wobbling-mode-treatment-system
#2
Sangmin Lee, Chaeyeong Lee, Eun Hyuk Shin, Sungkoo Cho, Dae-Hyun Kim, Youngyih Han, Doo Ho Choi, Sung-Joon Ye, Jin Sung Kim
The primary objective of this study was to measure secondary neutron dose during proton therapy using a detector that covers the entire neutron energy range produced in proton therapy. We analyzed and compared the neutron dose during proton treatment with passive scattering and line scanning. The neutron ambient dose equivalents were measured with a 190 MeV wobbling and line-scanning proton beam. The center of a plastic water phantom (30 × 30 × 60 cm3) was placed at the isocenter. A Wide-Energy Neutron Detection Instrument (WENDI-2) was located 1m from the isocenter at four different angles (0°, 45°, 90° and 135°)...
April 24, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28436155/the-mobius-airo-mobile-ct-for-image-guided-proton-therapy-characterization-commissioning
#3
Jasmine A Oliver, Omar A Zeidan, Sanford L Meeks, Amish P Shah, Jason Pukala, Patrick Kelly, Naren R Ramakrishna, Twyla R Willoughby
PURPOSE: The purpose of this study was to characterize the Mobius AIRO Mobile CT System for localization and image-guided proton therapy. This is the first known application of the AIRO for proton therapy. METHODS: Five CT images of a Catphan(®) 504 phantom were acquired on the AIRO Mobile CT System, Varian EDGE radiosurgery system cone beam CT (CBCT), Philips Brilliance Big Bore 16 slice CT simulator, and Siemens SOMATOM Definition AS 20 slice CT simulator. DoseLAB software v...
April 24, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28426432/surface-as-a-motion-surrogate-for-gated-re-scanned-pencil-beam-proton-therapy
#4
Ye Zhang, Isabel Huth, Martin Wegner, Damien C Weber, Antony J Lomax
This simulation study investigated the dosimetric effectiveness and treatment efficiency of surface motion guided gating of pencil beam scanning (PBS) proton therapy for liver tumour treatments. Dedicated 4D dose calculations were performed for simulating gated treatments using 4DCT data for six patients derived from 4DMRI (4DCT(MRI)). Surface motion as a surrogate for tumour motion was extracted from the 4DMRI images and a linear internal-external correlation model applied to derive amplitude-based gating windows (GWs) of 10 and 5 mm...
April 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28423966/linear-energy-transfer-distributions-in-the-brainstem-depending-on-tumour-location-in-intensity-modulated-proton-therapy-of-paediatric-cancer
#5
Lars Fredrik Fjæra, Zuofeng Li, Kristian S Ytre-Hauge, Ludvig P Muren, Daniel J Indelicato, Yasmin Lassen-Ramshad, Grete May Engeseth, Marianne Brydøy, Andrea Mairani, Stella Flampouri, Olav Dahl, Camilla H Stokkevåg
BACKGROUND: For tumours near organs at risk, there is concern about unintended increase in biological dose from elevated linear energy transfer (LET) at the distal end of treatment fields. The objective of this study was therefore to investigate how different paediatric posterior fossa tumour locations impact LET and biological dose to the brainstem during intensity-modulated proton therapy (IMPT). MATERIAL AND METHODS: Multiple IMPT plans were generated for four different simulated tumour locations relative to the brainstem for a five-year-old male patient...
April 19, 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28422406/comparability-of-three-output-prediction-models-for-a-compact-passively-double-scattered-proton-therapy-system
#6
Sven Ferguson, Yong Chen, Clara Ferreira, Mohammad Islam, Vance P Keeling, Andy Lau, Salahuddin Ahmad, Hosang Jin
The purpose of this study was to investigate comparability of three output prediction models for a compact double-scattered proton therapy system. Two published output prediction models are commissioned for our Mevion S250 proton therapy system. Model A is a correction-based model (Sahoo et al., Med Phys, 2008;35(11):5088-5097) and model B is an analytical model which employs a function of r = (R'-M')/M' (Kooy et al., Phys Med Biol, 2005;50:5487-5456) where R' is defined as depth of distal 100% dose with straggling and M' is the width between distal 100% dose and proximal 100% dose with straggling instead of the theoretical definition due to more accurate output prediction...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28422381/comparison-of-multi-institutional-varian-probeam-pencil-beam-scanning-proton-beam-commissioning-data
#7
Ulrich W Langner, John G Eley, Lei Dong, Katja Langen
PURPOSE: Commissioning beam data for proton spot scanning beams are compared for the first two Varian ProBeam sites in the United States, at the Maryland Proton Treatment Center (MPTC) and Scripps Proton Therapy Center (SPTC). In addition, the extent to which beams can be matched between gantry rooms at MPTC is investigated. METHOD: Beam data for the two sites were acquired with independent dosimetry systems and compared. Integrated depth dose curves (IDDs) were acquired with Bragg peak ion chambers in a 3D water tank for pencil beams at both sites...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28411963/using-a-knowledge-based-planning-solution-to-select-patients-for-proton-therapy
#8
Alexander R Delaney, Max Dahele, Jim P Tol, Ingrid T Kuijper, Ben J Slotman, Wilko F A R Verbakel
BACKGROUND AND PURPOSE: Patient selection for proton therapy by comparing proton/photon treatment plans is time-consuming and prone to bias. RapidPlan™, a knowledge-based-planning solution, uses plan-libraries to model and predict organ-at-risk (OAR) dose-volume-histograms (DVHs). We investigated whether RapidPlan, utilizing an algorithm based only on photon beam characteristics, could generate proton DVH-predictions and whether these could correctly identify patients for proton therapy...
April 12, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/28410691/quantification-of-the-uncertainties-of-a-biological-model-and-their-impact-on-variable-rbe-proton-treatment-plan-optimization
#9
A F Resch, G Landry, F Kamp, G Cabal, C Belka, J J Wilkens, K Parodi, G Dedes
PURPOSE: In proton radiation therapy, a relative biological effectiveness (RBE) equal to 1.1 is currently assumed, although biological experiments show that it is not constant. The purpose of this study was to quantify the uncertainties of a published biological model and explore their impact on variable RBE treatment plan (TP) optimization. METHODS: Two patient cases with a high and a low (α/β)x tumor were investigated. Firstly, intensity modulated proton therapy TPs assuming constant RBE were derived, and subsequently the variable RBE weighted dose (RWD), including the uncertainty originating in the fit to the experimental data and the uncertainty of the (α/β)x, were calculated...
April 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28402289/a-gas-scintillator-detector-for-2d-dose-profile-monitoring-in-pencil-beam-scanning-and-pulsed-beam-proton-radiotherapy-treatments
#10
Steven E Vigdor, Alexander Klyachko, Keith Solberg, Mark Pankuch
In order to address dosimetry demands during proton therapy treatments utilizing pencil beam scanning and/or pulsed beam accelerators, we have developed a xenon-filled Gas Scintillation Detector (GSD) that can monitor delivered dose and two-dimensional beam centroid position pulse-by-pulse in real time, with high response linearity up to high instantaneous dose rates. We present design considerations for the GSD and results of beam tests carried out at operating proton therapy clinics. In addition to demonstrating spatial resolution with σ of a few hundred microns in each transverse dimension and relative dose precision better than 1% over large treatment areas, the test beam results also reveal the dependence of the GSD dose normalization on dose rate, beam energy, and gas impurities...
April 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28380636/the-role-of-image-guided-intensity-modulated-proton-therapy-in-glioma
#11
David R Grosshans, Radhe Mohan, Vinai Gondi, Helen A Shih, Anita Mahajan, Paul D Brown
Gliomas represent a broad spectrum of disease with life-expectancy outcomes ranging from months to decades. As our understanding of the molecular profiles of gliomas expands rapidly, practitioners are now better able to identify patients with favorable versus nonfavorable prognoses. Radiation therapy plays a key role in glioma treatment, improving disease control and oftentimes survival. However, for survivors, either long-term or short-term, radiation-induced cognitive impairments may negatively impact their quality of life...
April 1, 2017: Neuro-oncology
https://www.readbyqxmd.com/read/28379849/sparsity-constrained-split-feasibility-for-dose-volume-constraints-in-inverse-planning-of-intensity-modulated-photon-or-proton-therapy
#12
Scott Penfold, Rafał Zalas, Margherita Casiraghi, Mark Brooke, Yair Censor, Reinhard Schulte
A split feasibility formulation for the inverse problem of intensity-modulated radiation therapy treatment planning with dose-volume constraints included in the planning algorithm is presented. It involves a new type of sparsity constraint that enables the inclusion of a percentage-violation constraint in the model problem and its handling by continuous (as opposed to integer) methods. We propose an iterative algorithmic framework for solving such a problem by applying the feasibility-seeking CQ-algorithm of Byrne combined with the automatic relaxation method that uses cyclic projections...
April 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28379155/beam-on-imaging-of-short-lived-positron-emitters-during-proton-therapy
#13
Hans Jan Thomas Buitenhuis, Faruk Diblen, Karol Brzezinski, Sytze Brandenburg, Peter Dendooven
In-vivo dose delivery verification in proton therapy can be performed by positron emission tomography (PET) of the positron-emitting nuclei produced by the proton beam in the patient. A PET scanner installed in the treatment position of a proton therapy facility that takes data with the beam on will see very short-lived nuclides as well as longer-lived nuclides. The most important short-lived nuclide for proton therapy is <sup>12</sup>N (Dendooven <i>et al</i> 2015), which has a half-life of 11 ms...
April 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28369941/a-model-based-iterative-reconstruction-algorithm-dira-using-patient-specific-tissue-classification-via-dect-for-improved-quantitative-ct-in-dose-planning
#14
Alexandr Malusek, Maria Magnussony, Michael Sandborg, Gudrun Alm Carlsson
PURPOSE: To develop and evaluate-in a proof-of-concept configuration-a novel iterative reconstruction algorithm (DIRA) for quantitative determination of elemental composition of patient tissues for application to brachytherapy with low energy (< 50 keV) photons and proton therapy. METHODS: DIRA was designed as a model-based iterative reconstruction algorithm, which uses filtered backprojection, automatic segmentation and multimaterial tissue decomposition. The evaluation was done for a phantom derived from the voxelized ICRP 110 male phantom...
March 30, 2017: Medical Physics
https://www.readbyqxmd.com/read/28366554/comparative-study-of-the-calculated-risk-of-radiation-induced-cancer-after-photon-and-proton-beam-based-radiosurgery-of-liver-metastases
#15
Gracinda Mondlane, Michael Gubanski, Pehr A Lind, Ana Ureba, Albert Siegbahn
INTRODUCTION: The potential of proton therapy to improve the sparing of the healthy tissue has been demonstrated in several studies. However, even small doses delivered to the organs at risk (OAR) may induce long-term detriments after radiotherapy. In this study, we investigated the possibility to reduce the risk of radiation-induced secondary cancers with intensity modulated proton therapy (IMPT), when used for radiosurgery of liver metastases. MATERIAL AND METHODS: Ten patients, previously treated for liver metastases with photon-beam based stereotactic body radiation therapy (SBRT) were retrospectively planned for radiosurgery with IMPT...
March 30, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28365895/does-proton-therapy-have-a-future-in-cns-tumors
#16
REVIEW
Stephanie E Combs
Proton therapy is characterized by certain physical properties leading to a reduction in integral dose. As proton therapy becomes more widely available, the ongoing discussion on the real indications for proton therapy becomes more important. In the present article, data on proton therapy for tumors of the central nervous system (CNS) is summarized and discussed in view of modern photon treatments. Still today, no randomized controlled trials are available confirming any clinical benefit of protons in CNS tumors...
March 2017: Current Treatment Options in Neurology
https://www.readbyqxmd.com/read/28359341/monitoring-of-breathing-motion-in-image-guided-pbs-proton-therapy-comparative-analysis-of-optical-and-electromagnetic-technologies
#17
Giovanni Fattori, Sairos Safai, Pablo Fernández Carmona, Marta Peroni, Rosalind Perrin, Damien Charles Weber, Antony John Lomax
BACKGROUND: Motion monitoring is essential when treating non-static tumours with pencil beam scanned protons. 4D medical imaging typically relies on the detected body surface displacement, considered as a surrogate of the patient's anatomical changes, a concept similarly applied by most motion mitigation techniques. In this study, we investigate benefits and pitfalls of optical and electromagnetic tracking, key technologies for non-invasive surface motion monitoring, in the specific environment of image-guided, gantry-based proton therapy...
March 31, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28358666/a-study-of-the-beam-specific-interplay-effect-in-proton-pencil-beam-scanning-delivery-in-lung-cancer
#18
Minglei Kang, Sheng Huang, Timothy D Solberg, Rulon Mayer, Andy Thomas, Boon-Keng Kevin Teo, James E McDonough, Charles B Simone, Liyong Lin
BACKGROUND: For lung tumors with large motion amplitudes, the use of proton pencil beam scanning (PBS) can produce large dose errors. In this study, we assess under what circumstances PBS can be used to treat lung cancer patients who exhibit large tumor motion, based on the quantification of tumor motion and the dose interplay. MATERIAL AND METHODS: PBS plans were optimized on average 4DCT datasets using a beam-specific PTV method for 10 consecutive patients with locally advanced non-small-cell-lung-cancer (NSCLC) treated with proton therapy to 6660/180 cGy...
April 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28341315/initial-clinical-experience-of-postmastectomy-intensity-modulated-proton-therapy-in-patients-with-breast-expanders-with-metallic-ports
#19
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
#20
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
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