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https://www.readbyqxmd.com/read/28687288/does-collimation-affect-patient-dose-in-antero-posterior-thoraco-lumbar-spine
#1
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
#2
Włodzimierz Grabowicz, Joanna Karolina Domienik-Andrzejewska, Konrad Masiarek, Tomasz Górnik, Tomasz Grycewicz, Marcin Brodecki, Andrzej Lubiński
The aim of the present study is to analyse quantitatively the potential reduction of the doses to eye lens and the hands of an operator and a nurse by the pelvic lead blanket during coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA) procedures. Thermoluminescent dosimeters (TLDs) were used to assess dose levels to left eye lens and left and right fingers of both physician and nurses during single procedures performed with or without lead blanket. The measurements were carried out in one medical centre and include dosimetric data from100 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
#3
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
#4
Siti Rozaila Zahariman, M Khandaker, Siti Fairus Abdul Sani, Siti Sabtu, Yusoff Amin, Mohd Jamil Maah, David Bradley
The sensitivity of a novel silica-based fibre-form thermoluminescence dosimeter is 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, has been calibrated against commercially available 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-earths facility have been identified, TLDs (silica- as well as TLD-200 and TLD-100) in each case being buried within 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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
https://www.readbyqxmd.com/read/28398210/out-of-field-doses-from-pediatric-craniospinal-irradiations-using-3d-crt-imrt-helical-tomotherapy-and-electron-based-therapy
#14
Marijke De Saint-Hubert, Dirk Verellen, Kenneth Poels, Wouter Crijns, Federica Magliona, Tom Depuydt, Filip Vanhavere, Lara Struelens
Medulloblastoma treatment involves irradiation of the entire central nervous system, i.e. craniospinal irradiation (CSI). This is associated with the significant exposure of large volumes of healthy tissue and there is growing concern regarding treatment-associated side effects. The current study compares out-of-field organ doses in children receiving CSI through 3D-conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), helical tomotherapy (HT) and an electron-based technique, and includes radiation doses resulting from imaging performed during treatment...
July 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28300387/real-time-ray-casting-based-scatter-dose-estimation-for-c-arm-x-ray-system
#15
Zaid Alnewaini, Eric Langer, Philipp Schaber, Matthias David, Dominik Kretz, Volker Steil, Jürgen Hesser
OBJECTIVES: Dosimetric control of staff exposure during interventional procedures under fluoroscopy is of high relevance. In this paper, a novel ray casting approximation of radiation transport is presented and the potential and limitation vs. a full Monte Carlo transport and dose measurements are discussed. METHOD: The x-ray source of a Siemens Axiom Artix C-arm is modeled by a virtual source model using single Gaussian-shaped source. A Geant4-based Monte Carlo simulation determines the radiation transport from the source to compute scatter from the patient, the table, the ceiling and the floor...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28300368/reduction-in-stray-radiation-dose-using-a-body-shielding-device-during-external-radiation-therapy
#16
Shuxu Zhang, Shaohui Jiang, Quanbin Zhang, Shengqu Lin, Ruihao Wang, Xiang Zhou, Guoqian Zhang, Huaiyu Lei, Hui Yu
With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters (TLDs). The SRDs at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297279/difference-in-performance-between-3d-and-4d-cbct-for-lung-imaging-a-dose-and-image-quality-analysis
#17
Sheeba Thengumpallil, Kathleen Smith, Pascal Monnin, Jean Bourhis, François Bochud, Raphaël Moeckli
The study was to describe and to compare the performance of 3D and 4D CBCT imaging modalities by measuring and analyzing the delivered dose and the image quality. The 3D (Chest) and 4D (Symmetry) CBCT Elekta XVI lung IGRT protocols were analyzed. Dose profiles were measured with TLDs inside a dedicated phantom. The dosimetric indicator cone-beam dose index (CBDI) was evaluated. The image quality analysis was performed by assessing the contrast transfer function (CTF), the noise power spectrum (NPS) and the noise-equivalent quanta (NEQ)...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296300/experimental-validation-of-a-kv-source-model-and-dose-computation-method-for-cbct-imaging-in-an-anthropomorphic-phantom
#18
Yannick Poirier, Mauro Tambasco
We present an experimental validation of a kilovoltage (kV) X-ray source characterization model in an anthropomorphic phantom to estimate patient-specific absorbed dose from kV cone-beam computed tomography (CBCT) imaging procedures and compare these doses to nominal weighted CT-dose index (CTDIw) dose estimates. We simulated the default Varian on-board imager 1.4 (OBI) default CBCT imaging protocols (i.e., standard-dose head, low-dose thorax, pelvis, and pelvis spotlight) using our previously developed and easy to implement X-ray point-source model and source characterization approach...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28290334/gonad-dose-in-ap-pelvis-radiography-impact-of-anode-heel-orientation
#19
H A A B Mraity, A England, P Hogg
PURPOSE: For antero posterior (AP) pelvis radiographic examination, determine the impact of anode heel orientation on female/male gonad dose. METHODS: High sensitivity thermo-luminescent dosimeters (TLDs) were used with an ATOM dosimetry phantom; the phantom was positioned for AP pelvis. TLDs were placed into the testes and ovaries. Radiation dose received by these organs was measured with the feet toward anode and feet toward the cathode. kVp, mAs and SID were manipulated to generate a range of exposures...
February 2017: Radiography
https://www.readbyqxmd.com/read/28266870/evaluation-of-different-low-dose-multidetector-ct-and-cone-beam-ct-protocols-in-maxillary-sinus-imaging-part-i-an-in-vitro-study
#20
Abeer A Almashraqi, Eman A Ahmed, Nashwa S Mohamed, Imad H Barngkgei, Nader A Elsherbini, Esam S Halboub
OBJECTIVES: This in vitro study aimed to assess radiation dose and image quality of different low-dose multidetector CT (MDCT) and CBCT imaging protocols in comparison with the standard MDCT protocol for maxillary sinus imaging. METHODS: Effective dose (E) and image quality of 10 MDCT (changing effective milliampere second starting from 141.3 EmAs to 20 EmAs) and 3 CBCT protocols (changing milliampere second and voxel size) were assessed throughout scanning an anthropomorphic head and neck Alderson Rando phantom...
April 12, 2017: Dento Maxillo Facial Radiology
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