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Proton Beam

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https://www.readbyqxmd.com/read/28644820/investigation-of-real-tissue-water-equivalent-path-lengths-using-an-efficient-dose-extinction-method
#1
Rongxiao Zhang, Esther Baer, Kyung-Wook Jee, Gregory C Sharp, Jay Flanz, Hsiao-Ming Lu
For proton therapy, an accurate conversion of CT HU to relative stopping power (RSP) is essential. Validation of the conversion based on real tissue samples is more direct than the current practice solely based on tissue substitutes and can potentially address variations over the population. Based on a novel dose extinction method, we measured water equivalent path lengths (WEPL) on animal tissue samples to evaluate the accuracy of CT HU to RSP conversion and potential variations over a population. A broad proton beam delivered a spread out Bragg peak to the samples sandwiched between a water tank and a 2D ion-chamber detector...
June 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28635614/advanced-treatment-planning-using-direct-4d-optimisation-for-pencil-beam-scanned-particle-therapy
#2
Kinga Bernatowicz, Ye Zhang, Rosalind Lucy Perrin, Damien Charles Weber, Antony John Lomax
We report on development of a new four-dimensional (4D) optimisation approach for scanned proton beams, which incorporates both irregular motion patterns and the delivery dynamics of the treatment machine into the plan optimiser. Furthermore, we assess the effectiveness of this technique to reduce dose to critical structures in proximity to moving targets, while maintaining effective target dose homogeneity and coverage. The proposed approach has been tested using both a simulated phantom and a clinical liver cancer case, and allows for realistic 4D calculations and optimisation using irregular breathing patterns extracted from e...
June 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28631017/proton-therapy-of-iris-melanoma-with-50%C3%A2-cge-influence-of-target-volume-on-clinical-outcome
#3
Aline I Riechardt, Bettina Karle, Dino Cordini, Jens Heufelder, Volker Budach, Antonia M Joussen, Johannes Gollrad
PURPOSE: The aim of this study was to evaluate local tumour control, incidence of radiation-induced glaucoma and associated interventions of sector-based and whole anterior segment proton beam therapy (PBT) for the treatment of iris melanoma. PATIENTS AND METHODS: We retrospectively analysed the data of 77 patients with iris melanoma who underwent PBT applied as 50 CGE in four daily fractions. Of the patients, 47 received PBT with a circular-shaped collimator and 30 with a conformal sector-shaped target volume...
June 19, 2017: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/28630005/transgenerational-effects-of-proton-beam-irradiation-on-caenorhabditis-elegans-germline-apoptosis
#4
Hyemin Min, Minhee Sung, Miseol Son, Ichiro Kawasaki, Yhong-Hee Shims
When treating cancer using radiation therapy, it is critical to increase patient survival rates and to reduce side effects. In this respect, proton beam radiation treatment performs better than other radiation treatments because of its high target specificity. However, complications still remain after proton beam radiation treatment. Among them, the risk to progeny after irradiation of their parents is a major concern. In this study, we analyzed the transgenerational effects of proton beam irradiation using the model organism Caenorhabditis...
June 16, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28627000/pencil-beam-scanned-protons-for-the-treatment-of-patients-with-ewing-sarcoma
#5
Damien C Weber, Fritz R Murray, Dora Correia, Alessandra Bolsi, Martina Frei-Welte, Alessia Pica, Antony J Lomax, Ralf Schneider, Barbara Bachtiary
BACKGROUND: Few data exist regarding the clinical outcome of patients with Ewing sarcoma (EWS) treated with pencil beam scanning proton therapy (PT). We report the outcome of children, adolescents and young adults (AYA) treated with PT at the Paul Scherrer Institute. MATERIALS: Thirty-eight patients (median age, 9.9 years) received a median dose of 54.9 Gy(RBE) (where RBE is relative biologic effectiveness). Size of the tumor ranged from 1.7 to 24 cm. Most common primary site was axial/pelvic (n = 27; 71%)...
June 19, 2017: Pediatric Blood & Cancer
https://www.readbyqxmd.com/read/28623412/long-term-follow-up-after-endoscopic-trans-sphenoidal-surgery-or-initial-observation-in-clivus-chordomas
#6
Jon Ramm-Pettersen, Radek Frič, Jon Berg-Johnsen
BACKGROUND: Resection of clivus chordomas through extensive skull base approaches is associated with high mortality and morbidity even in experienced hands. We report our experience with endoscopic trans-sphenoidal surgery, or a "wait-and-scan" strategy in selected patients. METHOD: Ten patients were diagnosed with clivus chordomas during an 8-year period. Six patients underwent primary treatment with endoscopic trans-sphenoidal surgery, followed by adjuvant proton-beam therapy in three of these patients...
June 16, 2017: Acta Neurochirurgica
https://www.readbyqxmd.com/read/28621993/dark-matter-search-in-a-proton-beam-dump-with-miniboone
#7
A A Aguilar-Arevalo, M Backfish, A Bashyal, B Batell, B C Brown, R Carr, A Chatterjee, R L Cooper, P deNiverville, R Dharmapalan, Z Djurcic, R Ford, F G Garcia, G T Garvey, J Grange, J A Green, W Huelsnitz, I L de Icaza Astiz, G Karagiorgi, T Katori, W Ketchum, T Kobilarcik, Q Liu, W C Louis, W Marsh, C D Moore, G B Mills, J Mirabal, P Nienaber, Z Pavlovic, D Perevalov, H Ray, B P Roe, M H Shaevitz, S Shahsavarani, I Stancu, R Tayloe, C Taylor, R T Thornton, R Van de Water, W Wester, D H White, J Yu
The MiniBooNE-DM Collaboration searched for vector-boson mediated production of dark matter using the Fermilab 8-GeV Booster proton beam in a dedicated run with 1.86×10^{20} protons delivered to a steel beam dump. The MiniBooNE detector, 490 m downstream, is sensitive to dark matter via elastic scattering with nucleons in the detector mineral oil. Analysis methods developed for previous MiniBooNE scattering results were employed, and several constraining data sets were simultaneously analyzed to minimize systematic errors from neutrino flux and interaction rates...
June 2, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28620561/patient-specific-qa-of-spot-scanning-proton-beams-using-radiochromic-film
#8
Maria F Chan, Chin-Cheng Chen, Chengyu Shi, Jingdong Li, Xiaoli Tang, Xiang Li, Dennis Mah
Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. A calibration using an EBT3 film, exposed by a 6-level step-wedge plan on a Proteus(®)PLUS proton system (IBA, Belgium), was performed at depths of 18, 20, 24cm using Plastic Water(®) (CIRS, Norfolk, VA)...
May 2017: International journal of medical physics, clinical engineering and radiation oncology
https://www.readbyqxmd.com/read/28611640/visual-loss-from-choroidal-melanoma-mimicking-neurological-syndromes
#9
Karim Hammamji, Ehud Reich, Amit Arora, Victoria M L Cohen, Mandeep S Sagoo
Melanoma of the eye is rare, but can mimic a range of disorders. This report highlights 2 cases of choroidal melanoma with vision loss mimicking neurological diagnoses. The first patient is a 41-year-old white male with a known history of multiple sclerosis and a previous episode of optic neuritis in the right eye, who presented with a 6-month history of decreased vision in the same eye, and occasional photopsiae. He was treated with 2 courses of oral steroids for presumed recurrent optic neuritis. After a temporary improvement in his symptoms, his vision worsened, following which he had a head MRI, which revealed a solid intraocular mass...
January 2017: Case Reports in Neurology
https://www.readbyqxmd.com/read/28610689/experimental-assessment-of-proton-dose-calculation-accuracy-in-inhomogeneous-media
#10
J Sorriaux, M Testa, H Paganetti, J Orban de Xivry, J A Lee, E Traneus, K Souris, S Vynckier, E Sterpin
PURPOSE: Proton therapy with Pencil Beam Scanning (PBS) has the potential to improve radiotherapy treatments. Unfortunately, its promises are jeopardized by the sensitivity of the dose distributions to uncertainties, including dose calculation accuracy in inhomogeneous media. Monte Carlo dose engines (MC) are expected to handle heterogeneities better than analytical algorithms like the pencil-beam convolution algorithm (PBA). In this study, an experimental phantom has been devised to maximize the effect of heterogeneities and to quantify the capability of several dose engines (MC and PBA) to handle these...
June 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28609301/a-light-weight-compact-proton-gantry-design-with-a-novel-dose-delivery-system-for-broad-energetic-laser-accelerated-beams
#11
U Masood, T E Cowan, W Enghardt, K M Hofmann, L Karsch, F Kroll, U Schramm, J J Wilkens, J Pawelke
Proton beams may provide superior dose-conformity in radiation therapy. However, the large sizes and costs limit the widespread use of proton therapy (PT). The recent progress in proton acceleration via high-power laser systems has made it a compelling alternative to conventional accelerators, as it could potentially reduce the overall size and cost of the PT facilities. However, the laser-accelerated beams exhibit different characteristics than conventionally accelerated beams, i.e. very intense proton bunches with large divergences and broad-energy spectra...
July 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28606833/impact-of-physiological-breathing-motion-for-breast-cancer-radiotherapy-with-proton-beam-scanning-an-in-silico-study
#12
Anna M Flejmer, Behnaz Chehrazi, Dan Josefsson, Iuliana Toma-Dasu, Alexandru Dasu
This study investigates the impact of breathing motion on proton breast treatment plans. Twelve patients with CT datasets acquired during breath-hold-at-inhalation (BHI), breath-hold-at-exhalation (BHE) and in free-breathing (FB) were included in the study. Proton plans were designed for the left breast for BHI and subsequently recalculated for BHE or designed for FB and recalculated for the extreme breath-hold phases. The plans were compared from the point of view of their target coverage and doses to organs-at-risk...
June 9, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28605745/current-standard-and-future-perspectives-in-non-surgical-therapy-for-hepatocellular-carcinoma
#13
Tobias Eggert, Tim F Greten
BACKGROUND: Hepatocellular carcinoma (HCC) is an aggressive liver tumor with a poor 5-year survival rate. Many HCCs are not amenable to surgical resection, because of tumor size, location, or because of the patient's poor liver function, a common obstacle to HCC therapy, because HCCs almost always develop in chronically inflamed livers. SUMMARY: In recent years, many efforts have been made to improve patient survival by conducting clinical trials investigating local and systemic treatment options for patients with unresectable tumors...
June 13, 2017: Digestion
https://www.readbyqxmd.com/read/28604370/development-of-a-synthetic-single-crystal-diamond-dosimeter-for-dose-measurement-of-clinical-proton-beams
#14
Cyril Moignier, Dominique Tromson, Ludovic de Marzi, Fanny Marsolat, Juan Carlos García Hernández, Mathieu Agelou, Michal Pomorski, Romuald Woo, Jean-Michel Bourbotte, Fabien Moignau, Delphine Lazaro, Alejandro Mazal
The scope of this work was to develop a synthetic single crystal diamond dosimeter (SCDD-Pro) for accurate relative dose measurements of clinical proton beams in water. Monte Carlo simulations were carried out based on the MCNPX code in order to investigate and reduce the dose curve perturbation caused by the SCDD-Pro. In particular, various diamond thicknesses were simulated to evaluate the influence of the active volume thickness (e AV) as well as the influence of the addition of a front silver resin (250 µm in thickness in front of the diamond crystal) on depth-dose curves...
July 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28598677/e2-decay-strength-of-the-m1-scissors-mode-of-156-gd-and-its-first-excited-rotational-state
#15
T Beck, J Beller, N Pietralla, M Bhike, J Birkhan, V Derya, U Gayer, A Hennig, J Isaak, B Löher, V Yu Ponomarev, A Richter, C Romig, D Savran, M Scheck, W Tornow, V Werner, A Zilges, M Zweidinger
The E2/M1 multipole mixing ratio δ_{1→2} of the 1_{sc}^{+}→2_{1}^{+} γ-ray decay in ^{156}Gd and hence the isovector E2 transition rate of the scissors mode of a well-deformed rotational nucleus has been measured for the first time. It has been obtained from the angular distribution of an artificial quasimonochromatic linearly polarized γ-ray beam of energy 3.07(6) MeV scattered inelastically off an isotopically highly enriched ^{156}Gd target. The data yield first direct support for the deformation dependence of effective proton and neutron quadrupole boson charges in the framework of algebraic nuclear models...
May 26, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28596284/prognostic-biopsy-of-choroidal-melanoma-an-optimised-surgical-and-laboratory-approach
#16
Martina Angi, Helen Kalirai, Azzam Taktak, Rumana Hussain, Carl Groenewald, Bertil E Damato, Heinrich Heimann, Sarah E Coupland
BACKGROUND: Accurate survival prognostication for patients with uveal melanoma (UM) enables effective patient counselling and permits personalised systemic surveillance for the early detection of metastases and, in high-risk patients, enrolment in any trials of systemic adjuvant therapy. The aim of this work is to determine the success of prognostic UM tumour biopsy using an improved surgical approach and optimised sample handling workflow. METHODS: Patients with UM treated by primary radiotherapy between 2011 and 2013 and who underwent a prognostic biopsy with cytology, multiplex ligation-dependent probe amplification and/or microsatellite analysis were included...
June 8, 2017: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/28593931/performance-characterization-of-a-3d-liquid-scintillation-detector-for-discrete-spot-scanning-proton-beam-systems
#17
Chinmay D Darne, Fahed Alsanea, Daniel G Robertson, Narayan Sahoo, Sam Beddar
Existing systems for proton beam dosimetry are limited in their ability to provide a complete, accurate, and detailed account of volumetric dose distribution. In this work, we describe the design and development of a portable, fast, and reusable liquid scintillator-based three-dimensional (3D) optical detection system for use in proton therapy. Our long-term goal is to use this system clinically for beam characterization, dosimetry, and quality assurance studies of discrete spot scanning proton beam systems...
June 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28590011/akt-as-locus-of-hydrogen-bond-network-in-cancer
#18
Ziv Radisavljevic
Generation and maintenance of a cancer complexity and robustness are impossible without hydrogen element. It is essential element for the cancer signaling through the AKT locus. Hyperactivated AKT locus by a positive feedback loops from the cancer hypoxic microenvironment generates a hydrogen bond network. Such network initiates protein-protein interaction at the AKT active site and at the same time stabilizes signal propagation. A hydrogen bond network conforms an entropy/enthalpy energetic process used for the interconversion of the AKT protein in metastasis formation and maintenance...
June 7, 2017: Journal of Cellular Biochemistry
https://www.readbyqxmd.com/read/28582266/a-beam-monitoring-and-validation-system-for-continuous-line-scanning-in-proton-therapy
#19
Grischa Klimpki, Serena Psoroulas, Christian Bula, Urs Rechsteiner, Michael Eichin, Damien Weber, Antony Lomax, David Meer
Line scanning represents a faster and potentially more flexible form of pencil beam scanning than conventional <i>step-and-shoot</i> irradiations. It seeks to minimize dead times in beam delivery whilst preserving the possibility to modulate the dose at any point in the target volume. Our second generation proton gantry features irradiations in line scanning mode, but it still lacks a dedicated monitoring and validation system that guarantees patient safety throughout beam delivery. We report on its design and implementation in this paper...
June 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28582265/application-of-fluence-field-modulation-to-proton-computed-tomography-for-proton-therapy-imaging
#20
Georgios Dedes, Ludovica De Angelis, Simon Rit, David Hansen, Claus Belka, Vladimir Bashkirov, Robert Johnson, George Coutrakon, Keith Schubert, Guillaume Landry, Reinhard Schulte, Katia Parodi
This simulation study presents the application of fluence field modulated computed tomography (FFMCT), initially developed for x-ray CT, to proton computed tomography (pCT). By using pencil beam (PB) scanning, fluence modulated pCT (FMpCT) may achieve variable image quality in a pCT image and imaging dose reduction. Three virtual phantoms, a uniform cylinder and two patients, were studied using Monte Carlo simulations of an ideal list-mode pCT scanner. Regions of interests (ROI) were selected for high image quality and only PBs intercepting them preserved full fluence (FF)...
June 5, 2017: Physics in Medicine and Biology
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