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https://www.readbyqxmd.com/read/28915893/dosimetric-comparison-of-different-treatment-modalities-for-stereotactic-radiotherapy
#1
Shih-Ming Hsu, Yuan-Chun Lai, Chien-Chung Jeng, Chia-Ying Tseng
BACKGROUND: The modalities for performing stereotactic radiotherapy (SRT) on the brain include the cone-based linear accelerator (linac), the flattening filter-free (FFF) volumetric modulated arc therapy (VMAT) linac, and tomotherapy. In this study, the cone-based linac, FFF-VMAT linac, and tomotherapy modalities were evaluated by measuring the differences in doses delivered during brain SRT and experimentally assessing the accuracy of the output radiation doses through clinical measurements...
September 16, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28905514/dosimetric-characterization-of-gms-bt-125-1-125-i-radioactive-seed-with-monte-carlo-simulations-and-experimental-measurement
#2
Nan Zhao, Ruijie Yang, Li Ren, Yi Fan, Junli Li, Jianguo Zhang
PURPOSE: To investigate the dosimetric characteristics of the new GMS BT-125-1 (125) I radioactive seed, including dose rate constant, radial dose functions, and anisotropy functions. METHODS: Dosimetric parameters of GMS BT-125-1 (125) I seed including dose rate constant, radial dose functions, and anisotropy functions were calculated using the Monte Carlo code of MCNP5, and measured with thermoluminescent dosimeters (TLDs). The results were compared with those of PharmaSeed BT-125-1, PharmaSeed BT-125-2 (125) I, and model 6711 (125) I seeds...
September 14, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28871483/a-comprehensive-dose-assessment-of-irradiated-hand-by-iridium-192-source-in-industrial-radiography
#3
S M Hosseini Pooya, M R Dashtipour, R Paydar, F Mianji, B Pourshahab
Among the various incidents in industrial radiography, inadvertent handling of sources by hands is one of the most frequent incidents in which some parts of the hands may be locally exposed to high doses. An accurate assessment of extremity dose assists medical doctors in selecting appropriate treatments, preventing the injury expansion in the region. In this study, a phantom was designed to simulate a fisted hand of a radiographer when the worker holds a radioactive source in their hands. The local doses were measured using implanted TLDs in the phantom at different distances from a source...
September 4, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28862215/small-field-depth-dose-profile-of-6-mv-photon-beam-in-a-simple-air-water-heterogeneity-combination-a-comparison-between-anisotropic-analytical-algorithm-dose-estimation-with-thermoluminescent-dosimeter-dose-measurement
#4
Abhijit Mandal, Chhape Ram, Ankur Mourya, Navin Singh
AIM OF STUDY: To establish trends of estimation error of dose calculation by anisotropic analytical algorithm (AAA) with respect to dose measured by thermoluminescent dosimeters (TLDs) in air-water heterogeneity for small field size photon. MATERIALS AND METHODS: TLDs were irradiated along the central axis of the photon beam in four different solid water phantom geometries using three small field size single beams. The depth dose profiles were estimated using AAA calculation model for each field sizes...
July 2017: Journal of Cancer Research and Therapeutics
https://www.readbyqxmd.com/read/28807441/whole-body-dose-and-energy-measurements-in-radiotherapy-by-a-combination-of-lif-mg-cu-p-and-lif-mg-ti
#5
Pascal Hauri, Uwe Schneider
PURPOSE: Long-term survivors of cancer who were treated with radiotherapy are at risk of a radiation-induced tumor. Hence, it is important to model the out-of-field dose resulting from a cancer treatment. These models have to be verified with measurements, due to the small size, the high sensitivity to ionizing radiation and the tissue-equivalent composition, LiF thermoluminescence dosimeters (TLD) are well-suited for out-of-field dose measurements. However, the photon energy variation of the stray dose leads to systematic dose errors caused by the variation in response with radiation energy of the TLDs...
August 11, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28796643/monte-carlo-and-experimental-determination-of-correction-factors-for-gamma-knife-perfexion-small-field-dosimetry-measurements
#6
E Zoros, A Moutsatsos, E P Pappas, E Georgiou, G Kollias, P Karaiskos, E Pantelis
Detector-, field size- and machine-specific correction factors are required for precise dosimetry measurements in small and non-standard photon fields. In this work, Monte Carlo (MC) simulation techniques were used to calculate the [Formula: see text] and [Formula: see text] correction factors for a series of ionization chambers, a synthetic microDiamond and diode dosimeters, used for reference and/or output factor (OF) measurements in the Gamma Knife Perfexion photon fields. Calculations were performed for the solid water (SW) and ABS plastic phantoms, as well as for a water phantom of the same geometry...
September 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28792787/validation-of-the-supportive-and-palliative-care-indicators-tool-in-a-geriatric-population
#7
Reine De Bock, Nele Van Den Noortgate, Ruth Piers
BACKGROUND: Timely identification of patients in need of palliative care is especially challenging in a geriatric population because of prognostic uncertainty. The Supportive and Palliative Care Indicators Tool (SPICT™) aims at facilitating this identification, yet has not been validated in a geriatric population. OBJECTIVE: This study validates the SPICT in a geriatric patient population admitted to the hospital. DESIGN: This is a retrospective cohort study...
August 9, 2017: Journal of Palliative Medicine
https://www.readbyqxmd.com/read/28687288/does-collimation-affect-patient-dose-in-antero-posterior-thoraco-lumbar-spine
#8
J B Robinson, R M Ali, A K Tootell, P Hogg
INTRODUCTION: The purpose of this study is to determine the effect of collimation on the lifetime attributable risk (LAR) of cancer incidence in all body organs (effective risk) in patients undergoing antero-posterior (AP) examinations of the spine. This is of particular importance for patients suffering from scoliosis as in their case regular repeat examinations are required and also because such patients are usually young and more susceptible to the effects of ionising radiation than are older patients...
August 2017: Radiography
https://www.readbyqxmd.com/read/28631620/effectiveness-of-pelvic-lead-blanket-to-reduce-the-doses-to-eye-lens-and-hands-of-interventional-cardiologists-and-assistant-nurses
#9
W Grabowicz, J Domienik-Andrzejewska, K Masiarek, T Górnik, T Grycewicz, M Brodecki, A Lubiński
The aim of the present study is to analyse quantitatively the potential reduction of doses to the eye lens and the hands of an operator and a nurse by the use of a pelvic lead blanket during coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA) procedures. Thermoluminescent dosimeters were used to assess dose levels to the left eye lens and fingers on both hands of both physician and nurses during single procedures performed with or without the lead blanket. The measurements were carried out at one medical centre and include dosimetric data from 100 procedures...
June 20, 2017: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/28618854/verification-of-organ-doses-calculated-by-a-dose-monitoring-software-tool-based-on-monte-carlo-simulation-in-thoracic-ct-protocols
#10
Nika Guberina, Saravanabavaan Suntharalingam, Kai Naßenstein, Michael Forsting, Jens Theysohn, Axel Wetter, Adrian Ringelstein
Background The importance of monitoring of the radiation dose received by the human body during computed tomography (CT) examinations is not negligible. Several dose-monitoring software tools emerged in order to monitor and control dose distribution during CT examinations. Some software tools incorporate Monte Carlo Simulation (MCS) and allow calculation of effective dose and organ dose apart from standard dose descriptors. Purpose To verify the results of a dose-monitoring software tool based on MCS in assessment of effective and organ doses in thoracic CT protocols...
January 1, 2017: Acta Radiologica
https://www.readbyqxmd.com/read/28581438/environmental-monitoring-through-use-of-silica-based-tld
#11
Z Siti Rozaila, M U Khandaker, S F Abdul Sani, Siti Norbaini Sabtu, Y M Amin, M J Maah, D A Bradley
The sensitivity of a novel silica-based fibre-form thermoluminescence dosimeter was tested off-site of a rare-earths processing plant, investigating the potential for obtaining baseline measurements of naturally occurring radioactive materials. The dosimeter, a Ge-doped collapsed photonic crystal fibre (PCFc) co-doped with B, was calibrated against commercially available thermoluminescent dosimetry (TLD) (TLD-200 and TLD-100) using a bremsstrahlung (tube-based) x-ray source. Eight sampling sites within 1 to 20 km of the perimeter of the rare-earth facility were identified, the TLDs (silica- as well as TLD-200 and TLD-100) in each case being buried within the soil at fixed depth, allowing measurements to be obtained, in this case for protracted periods of exposure of between two to eight months...
June 5, 2017: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/28545264/reduction-of-dose-to-the-contralateral-breast-by-superflab-use-in-radiation-therapy-for-mammary-carcinomas
#12
Akanksha Solanki, Athiyaman M, Hemalatha A, H S Kumar
Background: Radiation therapy is an integral part of multimodality treatment for locally advanced carcinoma of breast. Radiation doses to nearby critical normal structures like heart, lungs, and contralateral breast (CLB increases risk of second malignancies. In this study, we measured doses to the CLB and studied effects of a 1 cm thickness superflap. Materials and Methods: Fifty post-mastectomy carcinoma breast patients were included in the study.Radiation therapy of 50 Gy was planned in 25 fractions, 5 days a week, using the Eclipse Treatment Planning System version 8...
April 1, 2017: Asian Pacific Journal of Cancer Prevention: APJCP
https://www.readbyqxmd.com/read/28511893/assessment-of-the-effectiveness-of-attenuation-of-pb-aprons-by-using-tld-dosimetry-and-monte-carlo-calculations
#13
H Olaya Dávila, J A Díaz Merchán, H R Vega Carrillo, S A Martínez Ovalle
We developed an experimental set-up by using a continuous emission X-ray (Pantak DXT-3000) and three types of Pb aprons, with thicknesses of 0.25, 0.5, and 0.75mm, coated with Mylar fiber on their surface. Aprons were placed at a distance of 2.5m from the focus. Aluminum filtration was performed at the beam output to reproduce the qualities of narrow beams, N40 (Eeffective =33keV), N80 (Eeffective =65keV), and N100 (Eeffective =83keV), according to the ISO standard 4037 (1-3). Each apron was fixed with 10 thermoluminescent dosimeters (TLDs) over its surface, five dosimeters before and five dosimeters after irradiation with X-rays...
May 10, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28508830/dosimetric-verification-of-dose-calculation-algorithm-in-the-lung-during-total-marrow-irradiation-using-helical-tomotherapy
#14
Ewelina Konstanty, Julian Malicki, Katarzyna Łagodowska, Anna Kowalik
INTRODUCTION: Treatment of proliferative diseases of the hematopoietic system involves, in most cases, chemotherapy combined with radiation therapy, which is intended to provide adequate immunosuppressant. Conventionally, total body irradiation (TBI) was used; however, total marrow irradiation (TMI) performed with helical tomotherapy (HT) has been proposed as an alternative, with the aim of delivering the highest dose in the target area (skeleton bone). PURPOSE: The purpose of this study is to evaluate the accuracy of the dose calculation algorithm for the lung in TMI delivered with HT...
January 2017: Journal of Cancer Research and Therapeutics
https://www.readbyqxmd.com/read/28472430/evaluation-of-secondary-dose-and-cancer-risk-for-out-of-field-organ-in-esophageal-cancer-imrt-in-a-chinese-hospital-using-atom-phantom-measurements
#15
Yaping Qi, Lijuan He, Zhi Wang, Yuanyuan Liu, Hongdong Liu, Wanli Huo, X George Xu, Zhi Chen
There have been few studies on the secondary cancer after radiation treatment in Chinese hospitals. This study has measured out-of-field absorbed organ doses from intensity-modulated radiation therapy (IMRT) radiotherapy for esophageal cancer in a Chinese hospital and evaluated the risks of secondary cancer. The dose measurements were based on the thermo-luminescence dosemeter (TLD) and the ATOM® phantom, which represents an adult male. Over 100 TLD chips were placed in 35 different organ sites and one group of the same TLDs was set as background contrast...
May 3, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28469106/in-vitro-dosimetric-study-of-biliary-stent-loaded-with-radioactive-125-i-seeds
#16
Li-Hong Yao, Jun-Jie Wang, Charles Shang, Ping Jiang, Lei Lin, Hai-Tao Sun, Lu Liu, Hao Liu, Di He, Rui-Jie Yang
BACKGROUND: A novel radioactive 125I seed-loaded biliary stent has been used for patients with malignant biliary obstruction. However, the dosimetric characteristics of the stents remain unclear. Therefore, we aimed to describe the dosimetry of the stents of different lengths - with different number as well as activities of 125I seeds. METHODS: The radiation dosimetry of three representative radioactive stent models was evaluated using a treatment planning system (TPS), thermoluminescent dosimeter (TLD) measurements, and Monte Carlo (MC) simulations...
May 5, 2017: Chinese Medical Journal
https://www.readbyqxmd.com/read/28456222/coarse-spectral-characterization-of-warm-x-rays-at-the-z-facility-using-a-filtered-thermoluminescent-dosimeter-array
#17
V J Harper-Slaboszewicz, B A Ulmen, C T Parzyck, D J Ampleford, A L McCourt, K S Bell, C A Coverdale
A new collimated filtered thermoluminescent dosimeter (TLD) array has been developed at the Z facility to characterize warm x-rays (hν > 10 keV) produced by Z pinch radiation sources. This array includes a Kapton debris shield assembly to protect the TLDs from the source debris, a collimator array to limit the field of view of the TLDs to the source region, a filter wheel containing filters of aluminum, copper and tungsten up to 3 mm thick to independently filter each TLD, and a hermetically sealed cassette containing the TLDs as well as tungsten shielding on the sides and back of the array to minimize scattered radiation reaching the TLDs...
April 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28441973/treatment-limiting-decisions-in-patients-with-severe-traumatic-brain-injury-in-a-norwegian-regional-trauma-center
#18
Annette Robertsen, Reidun Førde, Nils Oddvar Skaga, Eirik Helseth
BACKGROUND: Treatment-limiting decisions (TLD) for severe traumatic brain injury (sTBI) have been sparsely studied. This study determine prevalence, main reason for, categories and timing of TLDs in a Norwegian regional trauma setting. METHODS: A retrospective study of a 2-year cohort of 579 sTBI patients admitted to Oslo University Hospital (OUH). Prospectively collected data in the OUH Trauma Registry were combined with retrospective data from a chart review regarding TLDs...
April 26, 2017: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine
https://www.readbyqxmd.com/read/28437010/technical-note-comparison-of-peripheral-patient-dose-from-mr-guided-60-co-therapy-and-6-mv-linear-accelerator-igrt
#19
Pascal Hauri, Roger A Hälg, Uwe Schneider
PURPOSE: The use of X-ray imaging in radiation therapy can give a substantial dose to the patient. A Cobalt machine combined with an magnetic resonance imaging (MRI) was recently introduced to clinical work. One positive aspect of using non-ionizing imaging devices is the reduction of the patient exposure. The purpose of this study was to quantify the difference in out-of-field dose to the patient between the image guided radiation therapy (IGRT) treatment applied with a linear accelerator with cone beam CT (CBCT) equipment and a Cobalt machine combined with an MRI...
April 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28419323/monte-carlo-simulation-used-to-calculate-energy-correction-factor-for-thermoluminescent-dosimeters-used-by-occupational-workers-on-pediatric-exams
#20
G Hoff, D Filipov, S Paschuk, H R Schelin, V Denyak
The main objective of this work is to simulate the X-ray scattered spectra by different pediatric phantoms (simulation of children subjected to barium meal procedures) to calculate an energy correction factor (ECF) to the reading of thermoluminescent dosimeters (TLDs). To perform this evaluation, the TLDs were positioned over three areas in two occupational workers: eyes, thyroid and hands. The Geant4 toolkit was used to define the spectra collected by TLDs, making possible to calculate the ECF. This work was developed in two stages: (1) evaluation of scattered spectra by different standard phantoms (newborn, 1, 5 and 10 years old); (2) definition of the ECF to the absorbed energy by each TLD...
April 13, 2017: Radiation Protection Dosimetry
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