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https://www.readbyqxmd.com/read/28198880/proton-therapy-dosimetry-using-the-scintillation-of-the-silica-fibers
#1
Arash Darafsheh, Reza Taleei, Alireza Kassaee, Jarod C Finlay
We investigate the feasibility of proton therapy dose measurement by using scintillation of a bare silica glass fiber. The emission spectra of the optical fiber at various depths in tissue-mimicking phantoms, irradiated with proton beams of energies 100-225 MeV show two distinct peaks at 460 and 650 nm whose nature is connected with the silica point defects. Our experimental results and Monte Carlo simulation showed that the Čerenkov radiation cannot be responsible for such a phenomenon. We showed that the intensity of the peak at 650 nm correlates with the proton dose with a minimal effect of ionization quenching, while the intensity peak at 460 nm under-reports the radiation dose...
February 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28195562/requirements-for-a-compton-camera-for-in-vivo-range-verification-of-proton-therapy
#2
Heide Rohling, Marlen Priegnitz, Sebastian Schoene, Andreas Schumann, Wolfgang Enghardt, Fernando Hueso-González, Guntram Pausch, Fine Fiedler
To ensure the optimal outcome of proton therapy, in-vivo range verification is highly desired. Prompt γ-ray imaging (PGI) is a possible approach for in-vivo range monitoring. For PGI, dedicated detection systems, e.g. Compton cameras, are currently under investigation. The presented paper deals with substantial requirements regarding hardware and software that a Compton camera used in clinical routine has to meet. By means of GEANT4 simulations, we investigate the load on the detectors and the percentage of background expected in a realistic irradiation and we simulate γ-ray detections subsequently used as input data for the reconstruction...
February 14, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28182581/application-of-single-and-dual-energy-ct-brain-tissue-segmentation-to-pet-monitoring-of-proton-therapy
#3
Bianca Berndt, Guillaume Landry, Florian Schwarz, Thomas Tessonnier, Florian Kamp, Georgios Dedes, Christian Thieke, Matthias Wuerl, Christopher Kurz, Ute Ganswindt, Frank Verhaegen, Juergen Debus, Claus Belka, Wieland Sommer, Maximilian Reiser, Julia Bauer, Katia Parodi
The purpose of this work was to evaluate the ability of single and dual energy computed tomography (SECT, DECT) to estimate tissue composition and density for usage in Monte Carlo (MC) simulations of irradiation induced β<sup>+</sup> activity distributions. This was done to assess the impact on positron emission tomography (PET) range verification in proton therapy. A DECT-based brain tissue segmentation method was developed for white matter (WM), grey matter (GM) and cerebrospinal fluid (CSF)...
February 9, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28166057/proton-therapy-of-prostate-cancer-by-anterior-oblique-beams-implications-of-setup-and-anatomy-variations
#4
M Moteabbed, A Trofimov, G C Sharp, Y Wang, A L Zietman, J A Efstathiou, H-M Lu
Proton therapy of prostate by anterior beams could offer an attractive option for treating patients with hip prosthesis and limiting the high-dose exposure to the rectum. We investigated the impact of setup and anatomy variations on the anterior-oblique (AO) proton plan dose, and strategies to manage these effects via range verification and adaptive delivery. Ten patients treated by bilateral (BL) passive-scattering proton therapy (79.2 Gy in 44 fractions) who underwent weekly verification CT scans were selected...
March 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28166055/a-comprehensive-and-efficient-daily-quality-assurance-for-pbs-proton-therapy
#5
O Actis, D Meer, S König, D C Weber, A Mayor
There are several general recommendations for quality assurance (QA) measures, which have to be performed at proton therapy centres. However, almost each centre uses a different therapy system. In particular, there is no standard procedure for centres employing pencil beam scanning and each centre applies a specific QA program. Gantry 2 is an operating therapy system which was developed at PSI and relies on the most advanced technological innovations. We developed a comprehensive daily QA program in order to verify the main beam characteristics to assure the functionality of the therapy delivery system and the patient safety system...
March 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28162946/first-clinical-report-of-proton-beam-therapy-for-postoperative-radiotherapy-for-non-small-cell-lung-cancer
#6
Jill S Remick, Caitlin Schonewolf, Peter Gabriel, Abigail Doucette, William P Levin, John C Kucharczuk, Sunil Singhal, Taine T V Pechet, Ramesh Rengan, Charles B Simone, Abigail T Berman
BACKGROUND AND PURPOSE: The characteristic Bragg peak of proton beam therapy (PBT) allows for sparing normal tissues beyond the tumor volume that may allow for decreased toxicities associated with postoperative radiation therapy (PORT). Here we report the first institutional experience with proton therapy for PORT in patients with non-small-cell lung cancer (NSCLC) and assess early toxicities and outcomes. MATERIALS AND METHODS: We identified 61 consecutive patients treated from 2011 to 2014 who underwent PORT for locally advanced NSCLC for positive microscopic margins and/or positive N2 lymph nodes (stage III), with 27 patients receiving PBT and 34 receiving intensity-modulated radiation therapy (IMRT)...
January 5, 2017: Clinical Lung Cancer
https://www.readbyqxmd.com/read/28152725/implementing-psychosocial-distress-screening-across-a-health-system-herding-cats-or-herding-cats
#7
(no author information available yet)
: 113 Background: With the American College of Surgeons Commission on Cancer 2015 Standards in hand, Penn Medicine embarked on a project to formulate an entity-wide plan for the provision of psychosocial distress screening. Identifying psychosocial distress and providing resources to meet those needs is an essential component of quality cancer care. Penn Medicine and the Abramson Cancer Center provided more than 91,000 chemotherapy treatments, 121,000 radiation treatments, and 14,000 proton therapy treatments in FY 15 in urban, suburban and rural settings with wide variations in resources...
March 2016: Journal of Clinical Oncology: Official Journal of the American Society of Clinical Oncology
https://www.readbyqxmd.com/read/28152693/assessing-the-cost-of-cancer-care-delivery-using-a-time-driven-activity-based-costing-software
#8
Alexis B Guzman, Yu-Ting Huang, Monica DelValle-Garza, Christian C Kolom, Xin Zhao, Danson N Mutua, Krishan Dhingra, Thomas W Feeley
: 25 Background: Poor costing systems and measurement have led to cross-subsidies and cost-shifting in health care. A large academic cancer center has adopted Robert Kaplan's bottom-up cost accounting methodology called time-driven, activity-based costing (TDABC). TDABC in health care has been proven to be an effective cost accounting tool to measure and improve care delivery by standardizing and creating transparency around patient care processes. The project aims to process map and identify event triggers associated with each process map, use a software applications to compute the costs and resource capacities...
March 2016: Journal of Clinical Oncology: Official Journal of the American Society of Clinical Oncology
https://www.readbyqxmd.com/read/28151727/contour-scanning-for-penumbra-improvement-in-pencil-beam-scanned-proton-therapy
#9
Gabriel Meier, Dominic Leiser, Rico Besson, Alexandre Mayor, Sairos Safai, Damien Weber, Antony Lomax
Proton therapy, especially in the form of pencil beam scanning (PBS), allows for the delivery of highly conformal dose distributions for complex tumor geometries. However, due to scattering of protons inside the patient, lateral dose gradients cannot be arbitrarily steep, which is of importance in cases with organs at risk (OARs) in close proximity to or overlapping planning target volumes (PTVs). In the PBS approach, physical pencil beams are planned using a regular grid orthogonal to the beam direction. In this work, we propose an alternative to this commonly used approach, by defining pencil beams on an irregular grid which is concentric to the target contour...
February 2, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28143487/helical-tomotherapy-of-spinal-chordomas-french-multicentric-retrospective-study-of-a-cohort-of-30-cases
#10
Maxime Bobin, Christina Zacharatou, Paul Sargos, Véronique Brouste, Albert Lisbona, Marc-André Mahé, Georges Noël, Amandine Halley, Loïc Feuvret, Louis Gras, Stéphanie Hoppe, Bénédicte Henriques de Figueiredo, Guy Kantor
PURPOSE: To evaluate the efficacy and toxicity of helical tomotherapy (HT) in the management of spine chordomas when proton therapy is unavailable or non-feasible. METHODS AND MATERIALS: Between 2007 and 2013, 30 patients with biopsy-proven chordomas were treated by HT in five French institutions. Information regarding local control (LC), overall survival (OS), progression-free survival (PFS) and metastasis-free survival (MFS) was collected. Clinical efficacy, toxicity and treatment quality were evaluated...
January 31, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28140380/near-real-time-automated-dose-restoration-in-impt-to-compensate-for-daily-tissue-density-variations-in-prostate-cancer
#11
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/28139305/long-term-outcome-of-phase-i-ii-prospective-study-of-dose-escalated-proton-therapy-for-early-stage-non-small-cell-lung-cancer
#12
Joe Y Chang, Wencheng Zhang, Ritsuko Komaki, Noah C Choi, Shen Chan, Daniel Gomez, Michael O'Reilly, Melenda Jeter, Michael Gillin, Xiaorong Zhu, Xiaodong Zhang, Radhe Mohan, Stephen Swisher, Stephen Hahn, James D Cox
PURPOSE: The aim of this phase I/II study was to assess the long-term clinical benefits and toxicities of proton beam therapy for medically inoperable early-stage non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: From June 2006 to September 2011, 35 patients with medically inoperable T1N0M0 (central or superior location, 12 patients) or T2-3N0M0 (any location, 23 patients) NSCLC were treated with 87.5Gy at 2.5Gy/fraction of proton therapy. Toxicities were scored according to the Common Terminology Criteria for Adverse Events, version 4...
January 27, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/28133755/evaluation-of-motion-mitigation-using-abdominal-compression-in-the-clinical-implementation-of-pencil-beam-scanning-proton-therapy-of-liver-tumors
#13
Liyong Lin, Kevin Souris, Minglei Kang, Adam Glick, Haibo Lin, Sheng Huang, Kristin Stützer, Guillaume Janssens, Edmond Sterpin, John A Lee, Timothy D Solberg, James E McDonough, Charles B Simone, Edgar Ben-Josef
PURPOSE: To determine whether individual liver tumor patients can be safely treated with pencil beam scanning proton therapy. This study reports a planning preparation workflow that can be used for beam angle selection and the evaluation of the efficacy of abdominal compression (AC) to mitigate motion. METHODS: Four-dimensional computed tomography scans (4DCT) with and without AC were available from 10 liver tumor patients with fluoroscopy-proven motion reduction by AC, previously treated using photons...
December 9, 2016: Medical Physics
https://www.readbyqxmd.com/read/28131731/spectroscopic-study-of-prompt-gamma-emission-for-range-verification-in-proton-therapy
#14
Laurent Kelleter, Aleksandra Wrońska, Judith Besuglow, Adam Konefał, Karim Laihem, Johannes Leidner, Andrzej Magiera, Katia Parodi, Katarzyna Rusiecka, Achim Stahl, Thomas Tessonnier
We present the results of an investigation of the prompt-gamma emission from an interaction of a proton beam with phantom materials. Measurements were conducted with a novel setup allowing the precise selection of the investigated depth in the phantom, featuring three different materials composed of carbon, oxygen and hydrogen. We studied two beam energies of 70.54 and 130.87MeV and two detection angles: 90° and 120°. The results are presented in form of profiles of the prompt-gamma yield as a function of depth...
January 25, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28129665/optimization-of-the-mechanical-collimation-for-minibeam-generation-in-proton-minibeam-radiation-therapy
#15
Consuelo Guardiola, Cécile Peucelle, Yolanda Prezado
PURPOSE: The dose tolerances of normal tissues continue to be the main barrier in radiation therapy. To lower it, a novel concept based on a combination of proton therapy and the use of arrays of parallel and thin beams has been recently proposed: proton minibeam radiation therapy (pMBRT). It allies the inherent advantages of protons with the remarkable normal tissue preservation observed when irradiated with submillimetric spatially fractionated beams. Due to multiple Coulomb scattering, the tumor receives a homogeneous dose distribution, while normal tissues in the beam's path benefit from the spatial fractionation of the dose...
January 27, 2017: Medical Physics
https://www.readbyqxmd.com/read/28121631/prediction-and-compensation-of-magnetic-beam-deflection-in-mr-integrated-proton-therapy-a-method-optimized-regarding-accuracy-versatility-and-speed
#16
Sonja M Schellhammer, Aswin L Hoffmann
The integration of magnetic resonance imaging (MRI) and proton therapy for on-line image-guidance is expected to reduce dose delivery uncertainties during treatment. Yet, the proton beam experiences a Lorentz force induced deflection inside the magnetic field of the MRI scanner, and several methods have been proposed to quantify this effect. We analyze their structural differences and compare results of both analytical and Monte Carlo models. We find that existing analytical models are limited in accuracy and applicability due to critical approximations, especially including the assumption of a uniform magnetic field...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28114114/scenario-based-radiation-therapy-margins-for-patient-setup-organ-motion-and-particle-range-uncertainty
#17
Rasmus Bokrantz, Albin Fredriksson
This work extends and validates the scenario-based generalization of margins presented in Fredriksson and Bokrantz (2016 Phys. Med. Biol. 61 2067-82). Scenario-based margins are, in their original form, a method for robust planning under setup uncertainty where the sum of a plan evaluation criterion over a set of scenarios is optimized. The voxelwise penalties in the summands are weighted by a distribution of coefficients defined such that the method is mathematically equivalent to the use of conventional geometric margins if the scenario doses are calculated using the static dose cloud approximation...
February 21, 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
#18
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/28114106/a-phenomenological-relative-biological-effectiveness-approach-for-proton-therapy-based-on-an-improved-description-of-the-mixed-radiation-field
#19
A Mairani, I Dokic, G Magro, T Tessonnier, J Bauer, T T Böhlen, M Ciocca, A Ferrari, P R Sala, O Jäkel, J Debus, T Haberer, A Abdollahi, K Parodi
Proton therapy treatment planning systems (TPSs) are based on the assumption of a constant relative biological effectiveness (RBE) of 1.1 without taking into account the found in vitro experimental variations of the RBE as a function of tissue type, linear energy transfer (LET) and dose. The phenomenological RBE models available in literature are based on the dose-averaged LET (LET D ) as an indicator of the physical properties of the proton radiation field. The LET D values are typically calculated taking into account primary and secondary protons, neglecting the biological effect of heavier secondaries...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28104299/liquid-fiducial-marker-applicability-in-proton-therapy-of-locally-advanced-lung-cancer
#20
Jonas Scherman Rydhög, Rosalind Perrin, Rasmus Irming Jølck, Francis Gagnon-Moisan, Klaus Richter Larsen, Paul Clementsen, Steen Riisgaard de Blanck, Gitte Fredberg Persson, Damien Charles Weber, Tony Lomax, Thomas Lars Andresen, Per Munck Af Rosenschold
BACKGROUND AND PURPOSE: We investigated the clinical applicability of a novel liquid fiducial marker (LFM) for image-guided pencil beam scanned (PBS) proton therapy (PBSPT) of locally advanced lung cancer (LALC). MATERIALS AND METHODS: The relative proton stopping power (RSP) of the LFM was calculated and measured. Dose perturbations of the LFM and three solid markers, in a phantom, were measured. PBSPT treatment planning on computer tomography scans of five patients with LALC with the LFM implanted was performed with 1-3 fields...
January 16, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
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