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radiation dosimetry

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https://www.readbyqxmd.com/read/28429827/a-descriptive-and-broadly-applicable-model-of-therapeutic-and-stray-absorbed-dose-from-6-mv-to-25-mv-photon-beams
#1
Christopher W Schneider, Wayne D Newhauser, Lydia J Wilson, Uwe Schneider, Robert Kaderka, Saveta Miljanić, Željka Knežević, Liliana Stolarcyzk, Marco Durante, Roger M Harrison
PURPOSE: To develop a simple model of therapeutic and stray absorbed dose for a variety of treatment machines and techniques without relying on proprietary machine-specific parameters. METHODS: Dosimetry measurements conducted in this study and from the literature were used to develop an analytical model of absorbed dose from a variety of treatment machines and techniques in the 6 MV to 25 MV interval. A modified one-dimensional gamma-index analysis was performed to evaluate dosimetric accuracy of the model on an independent dataset consisting of measured dose profiles from seven treatment units spanning four manufacturers...
April 21, 2017: Medical Physics
https://www.readbyqxmd.com/read/28428468/multicenter-investigation-of-the-effective-dose-for-whole-body-ct-scanning
#2
Toshimitsu Sato, Yukihiro Saito, Nobutoshi Saito, Makoto Ooba
OBJECTIVE: To study whether the actual radiation exposure is different between computed tomography (CT) scanners and medical centers when the same patient is scanned, we investigated the actual effective doses for a whole body (Chest-Pelvis) CT scan in a multicenter study. MATERIALS AND METHODS: Data from subjects were collected using 12 CT scanners at six medical centers in Yamagata city. Effective-dose data were acquired by scanning the same phantom (ATOM Dosimetry Phantoms Model702-B) using 120 kV tube voltage...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28427834/doped-silica-fibre-thermoluminescence-measurements-of-radiation-dose-in-the-use-of-223-ra
#3
Bradley, S F Abdul Sani, A S Siti Shafiqah, S M Collins, R P Hugtenburg, H A Abdul Rashid, Nurul Najua Zulkepely, M J Maah
Using tailor-made sub-mm dimension doped-silica fibres, thermoluminescent dosimetric studies have been performed for α-emitting sources of (223)RaCl2 (the basis of the Bayer Healthcare product Xofigo®). The use of (223)RaCl2 in the palliative treatment of bone metastases resulting from late-stage castration-resistant prostate cancer focuses on its favourable uptake in metabolically active bone metastases. Such treatment benefits from the high linear energy transfer (LET) and associated short path length (<100µm) of the α-particles emitted by (223)Ra and its decay progeny...
April 14, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28408529/targeted-alpha-therapy-of-mcrpc-with-225-actinium-psma-617-dosimetry-estimate-and-empirical-dose-finding
#4
Clemens Kratochwil, Frank Bruchertseifer, Hendrik Rathke, Marcus Bronzel, Christos Apostolidis, Wilko Weichert, Uwe Haberkorn, Frederick Lars Giesel, Alfred Morgenstern
To develop a treatment protocol for (225)Ac-PSMA-617 alpha-radiation therapy in advanced stage, metastatic castration-resistant prostate cancer patients with PSMA-positive tumor phenotype. Methods: A dosimetry estimate was calculated based on time-activity-curves derived from serially performed (177)Lu-PSMA-617 scans extrapolated to the physical half-life of (225)Ac, assuming instant decay of instable daughter nuclides. Salvage therapies empirically conducted with 50kBq/kg (n = 4), 100kBq/kg (n = 4), 150kBq/kg (n = 2), 200kBq/kg (n = 4) (225)Ac-PSMA-617 were evaluated retrospectively regarding toxicity and treatment response...
April 13, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/28402564/three-decades-of-occupational-individual-monitoring-at-the-university-of-s%C3%A3-o-paulo
#5
E Okuno, N K Umisedo, F S Cancio, M A Aldred, E M Yoshimura
As the ionizing radiation to which workers are exposed is related to possible harmful biological effect, its dose evaluation gains relevance. Although the effects of low doses are still controversial, the radiation protection authorities assume that any dose of ionizing radiation is potentially harmful to the human health and adopt the linear non-threshold model for the dose-effect relation. The Dosimetry Laboratory of the Institute of Physics of the University of São Paulo performs the external individual monitoring of workers exposed to X- and gamma-rays since 1981, with the technique of thermoluminescence...
April 11, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28398596/small-field-dose-measurements-using-plastic-scintillation-detector-in-heterogeneous-media
#6
Jinyu Xue, Jesse D McKay, Jimm Grimm, Chee-Wai Cheng, Ronald Berg, Shu-Ya Lisa Grimm, Qianyi Xu, Gopal Subedi, Indra J Das
PURPOSE: To evaluate a plastic scintillation detector for the measurement of small field dosimetry and to verify the accuracy of measured dose in comparison with Monte Carlo calculation in a heterogeneous medium. METHODS: The study is performed with CyberKnife planning and delivery system. The setup consists of a custom made solid lung phantom with the insert of an Exradin W1 scintillation detector or an Exradin A16 ion chamber. The measurement was done for a series of cone sizes from 5 mm to 60 mm, and the dose was calculated by Monte Carlo algorithm in MultiPlan workstation...
April 11, 2017: Medical Physics
https://www.readbyqxmd.com/read/28397396/insight-gained-from-responses-to-surveys-on-reference-dosimetry-practices
#7
Bryan Muir, Wesley Culberson, Stephen Davis, Gwe-Ya Kim, Yimei Huang, Sung-Woo Lee, Jessica Lowenstein, Arman Sarfehnia, Jeffrey Siebers, Naresh Tolani
PURPOSE: To present the results and discuss potential insights gained through surveys on reference dosimetry practices. METHODS: Two surveys were sent to medical physicists to learn about the current state of reference dosimetry practices at radiation oncology clinics worldwide. A short survey designed to maximize response rate was made publicly available and distributed via the AAPM website and a medical physics list server. Another, much more involved survey, was sent to a smaller group of physicists to gain insight on detailed dosimetry practices...
April 11, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28396725/three-dimensional-radiation-dosimetry-using-polymer-gel-and-solid-radiochromic-polymer-from-basics-to-clinical-applications
#8
REVIEW
Yoichi Watanabe, Leighton Warmington, N Gopishankar
Accurate dose measurement tools are needed to evaluate the radiation dose delivered to patients by using modern and sophisticated radiation therapy techniques. However, the adequate tools which enable us to directly measure the dose distributions in three-dimensional (3D) space are not commonly available. One such 3D dose measurement device is the polymer-based dosimeter, which changes the material property in response to radiation. These are available in the gel form as polymer gel dosimeter (PGD) and ferrous gel dosimeter (FGD) and in the solid form as solid plastic dosimeter (SPD)...
March 28, 2017: World Journal of Radiology
https://www.readbyqxmd.com/read/28395417/-dosimetry-verification-of-radioactive-seed-implantation-with-3d-printing-template-and-ct-guidance-for-paravertebral-retroperitoneal-malignant-tumor
#9
Z Ji, Y L Jiang, F X Guo, R Peng, H T Sun, J H Fan, J J Wang
Objective: To compare the dose distributions of postoperative plans with preoperative plans for seeds implantations of paravertebral/retroperitoneal tumors assisted by 3D printing guide template and CT guidance, explore the effects of the technology for seeds implantations in dosimetry level and provide data support for the optimization and standardization in seeds implantation. Methods: Between December 2015 and July 2016, a total of 10 patients with paravertebral/retroperitoneal tumors (12 lesions) received 3D printing template assist radioactive seeds implantations in department of radiation oncology of Peking University Third Hospital, and included in the study...
April 4, 2017: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/28392312/out-of-field-doses-in-radiotherapy-input-to-epidemiological-studies-and-dose-risk-models
#10
Roger Harrison
Out-of-field doses in radiotherapy have been increasingly studied in recent years because of the generally improved survival of patients who have received radiotherapy as part of their treatment for cancer and their subsequent risk of a second malignancy. This short article attempts to identify some current problems, challenges and opportunities for dosimetry developments in this field. Out-of-field doses and derived risk estimates contribute to general knowledge about radiation effects on humans as well as contributing to risk-benefit considerations for the individual patient...
April 6, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28391958/the-role-of-dosimetry-audit-in-lung-sbrt-multi-centre-clinical-trials
#11
Catharine H Clark, Coen W Hurkmans, Stephen F Kry
Stereotactic Body Radiotherapy (SBRT) in the lung is a challenging technique which requires high quality clinical trials to answer the un-resolved clinical questions. Quality assurance of these clinical trials not only ensures the safety of the treatment of the participating patients but also minimises the variation in treatment, thus allowing the lowest number of patient treatments to answer the trial question. This review addresses the role of dosimetry audits in the quality assurance process and considers what can be done to ensure the highest accuracy of dose calculation and delivery and it's assessment in multi-centre trials...
April 5, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28389764/efficacy-of-radpad-protective-drape-during-coronary-angiography
#12
B Kherad, T Jerichow, F Blaschke, M Noutsias, B Pieske, C Tschöpe, F Krackhardt
BACKGROUND: Ionizing radiation is an integral part of percutaneous coronary angiographies. Chronic exposure to low-dose radiation confers a risk for skin damage, eye lens opacities or cataracts, and malignant diseases to staff in the catheter laboratory. The RADPAD is a sterile surgical drape that reduces the effect of scatter radiation on the operator. We sought to assess the efficacy of RADPAD shields in reducing radiation dose experienced by operators during routine diagnostic coronary angiography...
April 7, 2017: Herz
https://www.readbyqxmd.com/read/28385795/-18-f-tetrafluoroborate-18-f-tfb-a-pet-probe-for-imaging-sodium-iodide-symporter-expression-whole-body-biodistribution-safety-and-radiation-dosimetry-in-thyroid-cancer-patients
#13
Jim O' Doherty, Maite Jauregui-Osoro, Teresa Brothwood, Teresa Szyszko, Paul Marsden, Michael O' Doherty, Gary Cook, Philip Blower, Val Lewington
Rationale: We report the safety, biodistribution and internal radiation dosimetry, in humans with thyroid cancer, of (18)F-tetrafluoroborate ((18)F-TFB), a novel PET radioligand for imaging the human sodium/iodide symporter (hNIS). Methods: Serial whole-body PET scans of 5 subjects with recently diagnosed with thyroid cancer were acquired prior to surgery for up to 4 hours after injection of 184 ± 15 MBq of (18)F-TFB. Activity was determined in whole blood, plasma and urine. Mean organ absorbed doses and effective doses were calculated via quantitative image analysis and using OLINDA/EXM software...
April 6, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/28385495/dosimetric-characterization-of-small-fields-using-a-plastic-scintillator-detector-a-large-multicenter-study
#14
Pietro Mancosu, Massimo Pasquino, Giacomo Reggiori, Laura Masi, Serenella Russo, Michele Stasi
PURPOSE: In modern radiation therapy accurate small fields dosimetry is a challenge and its standardization is fundamental to harmonize delivered dose in different institutions. This study presents a multicenter characterization of MLC-defined small field for Elekta and Varian linear accelerators. Measurements were performed using the Exradin W1 plastic scintillator detector. MATERIALS AND METHODS: The project enrolled 24 Italian centers. Each center performed Tissue Phantom Ratio (TPR), in-plane and cross-plane dose profiles of 0...
April 3, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28383157/development-of-a-novel-low-radiation-absorbent-lok-bar-to-reduce-x-ray-scattering-and-absorption-in-rapidarc-%C3%A2-treatment-planning-and-dose-delivery
#15
Hajime Monzen, Kazuki Kubo, Mikoto Tamura, Masaru Hayakawa, Yasumasa Nishimura
We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok-bar (VL-bar) as a benchmark. CT images were obtained with or without lok-bar, and then each image was visually evaluated for artifacts. The attenuation rates for each lok-bar were measured using a farmer-type ionization chamber (PTW30013) and the I'mRT phantom (IBA Dosimetry GmbH)...
April 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28379850/a-novel-geometry-dosimetry-label-fusion-method-in-multi-atlas-segmentation-for-radiotherapy-a-proof-of-concept-study
#16
Jina Chang, Zhen Tian, Weiguo Lu, Xuejun Gu, Mingli Chen, Steve B Jiang
Multi-atlas segmentation (MAS) has been widely used to automate the delineation of organs at risk (OARs) for radiotherapy. Label fusion is a crucial step in MAS to cope with the segmentation variabilities among multiple atlases. However, most existing label fusion methods do not consider the potential dosimetric impact of the segmentation result. In this proof-of-concept study, we propose a novel geometry-dosimetry label fusion method for MAS-based OAR auto-contouring, which evaluates the segmentation performance in terms of both geometric accuracy and the dosimetric impact of the segmentation accuracy on the resulting treatment plan...
April 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28378320/the-impact-of-smart-metal-artefact-reduction-algorithm-for-use-in-radiotherapy-treatment-planning
#17
Connor Guilfoile, Peter Rampant, Michael House
The presence of metal artefacts in computed tomography (CT) create issues in radiation oncology. The loss of anatomical information and incorrect Hounsfield unit (HU) values produce inaccuracies in dose calculations, providing suboptimal patient treatment. Metal artefact reduction (MAR) algorithms were developed to combat these problems. This study provides a qualitative and quantitative analysis of the "Smart MAR" software (General Electric Healthcare, Chicago, IL, USA), determining its usefulness in a clinical setting...
April 4, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28377138/daily-ct-guidance-improves-target-coverage-during-definitive-radiation-therapy-for-gastric-malt-lymphoma
#18
He Wang, Sarah A Milgrom, Bouthaina S Dabaja, Grace L Smith, Mary Martel, Chelsea C Pinnix
PURPOSE: Radiation therapy (RT) for gastric mucosa-associated lymphoid tissue (MALT) lymphoma is challenging because of variation in the stomach's position, size, and shape. We investigated the interfractional changes in stomach location, consequent dosimetric effects, and impact of daily computed tomography image guidance RT (CT-IGRT). METHODS AND MATERIALS: Twelve patients treated for gastric MALT lymphoma with intensity modulated radiation therapy, using a breath-hold technique and restriction of oral intake, were studied retrospectively...
March 6, 2017: Practical Radiation Oncology
https://www.readbyqxmd.com/read/28376826/the-risk-of-cataractogenesis-after-gamma-knife-radiosurgery-a-nationwide-population-based-case-control-study
#19
Cheng-Loong Liang, Po-Chou Liliang, Tai-Been Chen, Huan-Chen Hsu, Fu-Cheng Chuang, Kuo-Wei Wang, Hao-Kuang Wang, San-Nan Yang, Han-Jung Chen
BACKGROUND: Medical radiation is considered a factor responsible for cataractogenesis. However, the incidence of this ophthalmologic complication resulting from gamma knife radiosurgery (GKRS) has not yet been reported. The present study aimed to determine the risk of cataractogenesis associated with radiation exposure from GKRS. METHODS: This study used information from a random sample of one million persons enrolled in the nationally representative Taiwan National Health Insurance Research Database...
April 4, 2017: BMC Ophthalmology
https://www.readbyqxmd.com/read/28374124/external-dose-reconstruction-for-the-former-village-of-metlino-techa-river-russia-based-on-environmental-surveys-luminescence-measurements-and-radiation-transport-modelling
#20
M M Hiller, C Woda, N G Bougrov, M O Degteva, O Ivanov, A Ulanovsky, S Romanov
In the first years of its operation, the Mayak Production Association, a facility part of the Soviet nuclear weapons program in the Southern Urals, Russia, discharged large amounts of radioactively contaminated effluent into the nearby Techa River, thus exposing the people living at this river to external and internal radiations. The Techa River Cohort is a cohort intensely studied in epidemiology to investigate the correlation between low-dose radiation and health effects on humans. For the individuals in the cohort, the Techa River Dosimetry System describes the accumulated dose in human organs and tissues...
April 3, 2017: Radiation and Environmental Biophysics
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