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Radiobiology

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https://www.readbyqxmd.com/read/28078405/-radiosurgery-and-fractionated-stereotactic-radiotherapy-of-vestibular-schwannoma
#1
K Hamm, H-U Herold, G Surber, S Rosahl
Management of vestibular schwannoma (VS) should always be interdisciplinary and results better than the natural course. Particularly in small VS, either microsurgical resection or radiosurgery (RS) can be employed. RS is a special method (initially only possible stereotactically) for delivering high-precision radiation from many directions to the target point (the isocenter) in a single high dose. With the development of three different systems-Gamma Knife (Elekta, Stockholm, Sweden), special linear accelerators, and CyberKnife (Accuray, Sunnyvale, CA, USA)-the options were extended to 1-5 fractions for RS and multisession RS (msRS), and to up to 6 weeks of conventional fractionation as stereotactic radiotherapy (SRT)...
January 11, 2017: HNO
https://www.readbyqxmd.com/read/28063356/nanoparticles-for-radiooncology-mission-vision-challenges
#2
REVIEW
Leoni A Kunz-Schughart, Anna Dubrovska, Claudia Peitzsch, Alexander Ewe, Achim Aigner, Samuel Schellenburg, Michael H Muders, Silke Hampel, Giuseppe Cirillo, Francesca Iemma, Rainer Tietze, Christoph Alexiou, Holger Stephan, Kristof Zarschler, Orazio Vittorio, Maria Kavallaris, Wolfgang J Parak, Lutz Mädler, Suman Pokhrel
Cancer is one of the leading non-communicable diseases with highest mortality rates worldwide. About half of all cancer patients receive radiation treatment in the course of their disease. However, treatment outcome and curative potential of radiotherapy is often impeded by genetically and/or environmentally driven mechanisms of tumor radioresistance and normal tissue radiotoxicity. While nanomedicine-based tools for imaging, dosimetry and treatment are potential keys to the improvement of therapeutic efficacy and reducing side effects, radiotherapy is an established technique to eradicate the tumor cells...
December 14, 2016: Biomaterials
https://www.readbyqxmd.com/read/28054514/relative-biological-effectiveness-for-photons-implication-of-complex-dna-double-strand-breaks-as-critical-lesions
#3
Ying Liang, Qibin Fu, Xudong Wang, Feng Liu, Gen Yang, Chunxiong Luo, Ouyang Qi, Yugang Wang
Current knowledge in radiobiology ascribes the adverse biological effects of ionizing radiation primarily to the induction of DNA double-strand breaks (DSB), which is supposed to be potentially lethal and may be converted to lethal damage due to misrepair. Soft and ultrasoft x-rays have been found to bear elevated biological effectiveness for cell killing compared with conventional x-rays or 60Co γ-rays. This phenomenon is qualitatively interpreted as the increased level of DSB induction for low energy photons however a thorough quantitative reasoning is lacking...
January 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28048945/organotypic-spheroid-culture-to-mimic-radiation-induced-salivary-hypofunction
#4
H S Shin, H Y An, J S Choi, H J Kim, J Y Lim
Radiation treatment often leads to irreversible damage to normal salivary glands (SGs) because of their proximity to head and neck cancers. Optimization of the in vitro model of irradiation (IR)-induced SG damage is warranted to investigate pathophysiology and monitor treatment outcome. Here, we present an organotypic spheroid culture model to investigate the impact of IR on SGs and the mechanisms underlying IR-induced structural and functional changes. Human parotid epithelial cells were obtained from human parotid glands and plated on either plastic plates or Matrigel...
December 1, 2016: Journal of Dental Research
https://www.readbyqxmd.com/read/28048927/mo-fg-bra-05-dosimetric-and-radiobiological-validation-of-respiratory-gating-in-conventional-and-hypofractionated-radiotherapy-of-the-lung-effect-of-dose-dose-rate-gating-window-and-breathing-pattern
#5
L Cervino, D Soultan, N Pettersson, A Yock, M Cornell, J Aguilera, J Murphy, B Gill, S Advani, V Moiseenko
PURPOSE: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. METHODS: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048896/su-f-t-03-radiobiological-evaluation-of-a-directional-brachytherapy-device-surgically-implanted-following-ebrt
#6
M J Rivard, J G Emrich, J Poli
PURPOSE: Preceding surgical implantation following external-beam radiotherapy (EBRT) delivery, a radiobiological evaluation was performed for a new LDR Pd-103 directional brachytherapy device (CivaSheet). As this was the first case with the device used in combination with EBRT, there was concern to determine the appropriate prescription dose. METHODS: The radiobiological model of Dale (1985, 1989) was used for a permanent LDR implant including radioactive decay...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048749/su-f-r-49-a-novel-kinetic-model-for-prediction-of-tumor-local-control-for-patients-with-lung-cancer
#7
H Zhong, S Siddiqui, B Zhao, H Li, K Barton, F Siddiqui, B Movsas, I Chetty
PURPOSE: Modeling tumor control probability (TCP) can help optimize treatment plans for better treatment outcomes. This study sought to quantify the radiobiological parameters of the TCP model for patients with lung cancer. METHODS: A two-compartment kinetic model was developed to model tumor regression for five NSCLC patients. The model has three parameters: cell survival fraction, dead-cell-resolving time and tumor doubling time. The last one was extended to a function of tumor volume...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048671/su-f-t-104-determining-the-ntcp-parameters-of-pharyngeal-constrictors-and-proximal-esophagus-for-radiation-induced-swallowing-problems-recorded-six-months-after-radiation-therapy-for-head-and-neck-tumors
#8
P Mavroidis, A Price, M Kostich, R Amdur, W Mendenhall, N Sheets, R Green, S Das, L Marks, B Chera
PURPOSE: To estimate the radiobiological parameters of four NTCP models that describe the dose-response relations of pharyngeal constrictors and proximal esophagus regarding the severity of patient reported swallowing problems 6 months post chemo-radiotherapy. To identify the section/structure that best correlates with the manifestation of the clinical endpoints. Finally, to compare the goodness-of-fit of those models. METHODS: Forty-three patients were treated on a prospective multi-institutional phase II study for oropharyngeal squamous cell carcinoma...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048529/tu-h-campus-tep2-02-flash-irradiation-improves-the-therapeutic-index-following-gi-tract-irradiation
#9
E Schueler, S Trovati, G King, F Lartey, M Rafat, B Loo, P Maxim
PURPOSE: To investigate and characterize the radiobiological effectiveness of very high dose rate radiotherapy (FLASH) compared to conventional irradiation in an in vivo model. METHODS: The gastrointestinal (GI) tract of C57BL/6 mice were irradiated with doses ranging between 10 and 18 Gy using a custom stereotactic jig. A Varian Clinac 21EX was modified to allow dose rates ranging from 0.05 to 240 Gy/s at the position of the mirror. With the gantry at 180 degrees, the jig holding the individual animals was placed above the mirror to take advantage of the reduced source to target distance...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048418/su-f-sps-10-the-dosimetric-comparison-of-gammaknife-and-cyberknife-treatment-plans-for-brain-srs-treatment
#10
E Sanli, H Mabhouti, M Cebe, G Codel, P Pacaci, E Serin, N Kucuk, E Kucukmorkoc, M Doyuran, D Canoglu, A Altinok, H Acar, H Caglar Ozkok
PURPOSE: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. METHODS: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048387/mo-a-brc-00-tg167-clinical-recommendations-for-innovative-brachytherapy-devices-and-applicators
#11
Ravinder Nath
: Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048349/we-h-bra-04-biological-geometries-for-the-monte-carlo-simulation-toolkit-topasnbio
#12
A McNamara, J Perl, P Piersimoni, J Ramos-Mendez, B Faddegon, K Held, H Paganetti, J Schuemann
PURPOSE: New advances in radiation therapy are most likely to come from the complex interface of physics, chemistry and biology. Computational simulations offer a powerful tool for quantitatively investigating radiation interactions with biological tissue and can thus help bridge the gap between physics and biology. The aim of TOPAS-nBio is to provide a comprehensive tool to generate advanced radiobiology simulations. METHODS: TOPAS wraps and extends the Geant4 Monte Carlo (MC) simulation toolkit...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048306/we-fg-bra-04-a-portable-confocal-microscope-to-image-live-cell-damage-response-induced-by-therapeutic-radiation
#13
C McFadden, D Flint, D Sadetaporn, A Asaithamby, D Grosshans, G Sawakuchi
PURPOSE: To construct a custom and portable fluorescence confocal laser-scanning microscope (FCLSM) that can be placed in the path of therapeutic radiation beams to study real-time radiation-induced damage response in live cells. METHODS: We designed and constructed a portable FCLSM with three laser diodes for excitation (405, 488, and 635 nm). An objective lens focuses the excitation light and collects fluorescence from the sample. A pair of galvanometer mirrors scans/collects the laser beam/fluorescence along the focal plane (x/y-directions)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048304/su-g-tep3-02-determination-of-geometry-specific-backscatter-factors-for-radiobiology-studies
#14
N Viscariello, W Culberson, M Lawless, K Kunugi, L DeWerd
PURPOSE: Radiation biology research relies on an accurate radiation dose delivered to the biological target. Large field irradiations in a cabinet irradiator may use the AAPM TG-61 protocol. This relies on an air-kerma measurement and conversion to absorbed dose to water (Dw) on the surface of a water phantom using provided backscatter factors. Cell or small animal studies differ significantly from this reference geometry. This study aims to determine the impact of the lack of full scatter conditions in four representative geometries that may be used in radiobiology studies...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048206/su-f-t-685-evaluation-of-tumor-hypoxic-fraction-using-serial-volumetric-imaging-during-radiation-therapy
#15
A Chvetsov
PURPOSE: To develop a tumor response model which could be uses to compute tumor hypoxic fraction using serial volumetric tumor imaging. This algorithm may be used for treatment response assessment and also for guidance of more expensive PET imaging of hypoxia. METHODS: Previously developed two-level cell population tumor response model was modified to include a third cell level describing hypoxic and necrotic cells. This third level was considered constant value during radiotherapy treatment; therefore, inclusion additional parameter did not compromise stability of model fitting to imaging data...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048159/mo-a-brc-02-tg167-report-detailed-description
#16
M Rivard
: Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047870/tu-h-campus-tep2-03-high-sensitivity-and-high-resolution-fiber-based-micro-detector-for-sub-millimeter-preclinical-dosimetry
#17
E Izaguirre, S Pokhrel, S Hedrick, T Knewtson
PURPOSE: Current precision of small animal and cell micro-irradiators has continuously increased during the past years. Currently, preclinical irradiators can deliver sub-millimeter fields with micrometric precision but there are no water equivalent dosimeters to determine small field profiles and dose in the orthovoltage range of energies with micrometric resolution and precision. We have developed a fiber based micro-dosimeter with the resolution and dosimetric accuracy required for radiobiological research...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047860/tu-h-brc-04-feasibility-of-using-tomodirect-for-pulsed-reduced-dose-rate-radiotherapy
#18
M Geurts
PURPOSE: Pulsed reduced dose-rate radiotherapy (PRDR) is a technique used for treatment of recurrent disease where a planned treatment is split into 0.2 Gy pulses, each separated by three-minute intervals, to achieve a time averaged dose rate of 0.0667 Gy/min. This study investigated the feasibility of using TomoTherapy's fixed angle delivery feature (TomoDirect) to create high quality IMRT plans that meet the radiobiological constraints of PRDR. METHODS: Two plans (one craniospinal irradiation and a complex shaped temporal lobe re-irradiation) were created using a conventional technique and then TomoDirect...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047821/su-f-t-523-radiobiological-comparison-of-helical-tomotherapy-and-vmat-in-the-treatment-of-head-and-neck-tumors
#19
R Woods, P Mavroidis, M Lehman-Davis, M Kostich, T Cook, B Chera, S Das, J Lian
PURPOSE: This study aims at comparing the efficacy of Helical Tomotherapy (TOMO) and Volumetric Modulated Arc Therapy (VMAT) in producing highly conformal dose distributions in challenging head & neck cancer patients. Furthermore, to interpret the dosimetric findings into expected tissue response rates in order to estimate their clinical impact. METHODS: Seven patients were studied and for each patient two treatment plans (one TOMO and one VMAT) were created. Structures used for optimization were: high risk PTV, standard risk PTV, brainstem, spinal cord, parotid gland, larynx, mandible and surrounding tissue...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047770/su-f-sps-11-the-dosimetric-comparison-of-truebeam-2-0-and-cyberknife-m6-treatment-plans-for-brain-srs-treatment
#20
H Mabhouti, E Sanli, M Cebe, G Codel, P Pacaci, E Serin, N Kucuk, E Kucukmorkoc, M Doyuran, D Canoglu, A Altinok, H Acar, H Caglar Ozkok
PURPOSE: Brain stereotactic radiosurgery involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of Truebeam 2.0 and Cyberknife M6 treatment plans were made. METHODS: For Truebeam 2.0 machine, treatment planning were done using 2 full arc VMAT technique with 6 FFF beam on the CT scan of Randophantom simulating the treatment of sterotactic treatments for one brain metastasis...
June 2016: Medical Physics
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