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Radiation dose measurements

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https://www.readbyqxmd.com/read/28324825/synthesis-of-%C3%AE-ca2p2o7-tb-3-to-gamma-radiation-detection-by-thermoluminescence
#1
REVIEW
J Roman-Lopez, I B Lozano, E Cruz-Zaragoza, J I Guzman Castañeda, J A I Díaz-Góngora
In this work, luminescent emissions of beta-calcium pyrophosphate doped with terbium ions (β-Ca2P2O7:Tb(3+)) were studied. The Ca2P2O7:Tb(3+) powders were prepared by precipitation and annealed at 900°C for 2h was applied on the powders to observe the beta phase. Radioluminescence measurements showed emission bands related with (5)D3 ((5)D4)→(7)FJ transitions of Tb(3+) ions. Three overlapped peaks at 126, 165 and 220°C were observed in thermoluminescence response. A linear TL dose-response in the range of 0...
March 6, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28323641/metal-artifacts-in-computed-tomography-for-radiation-therapy-planning-dosimetric-effects-and-impact-of-metal-artifact-reduction
#2
Drosoula Giantsoudi, Bruno De Man, Joost Verburg, Alexei Trofimov, Yannan Jin, Ge Wang, Lars Gjesteby, Harald Paganetti
A significant and increasing number of patients receiving radiation therapy present with metal objects close to, or even within, the treatment area, resulting in artifacts in computed tomography (CT) imaging, which is the most commonly used imaging method for treatment planning in radiation therapy. In the presence of metal implants, such as dental fillings in treatment of head-and-neck tumors, spinal stabilization implants in spinal or paraspinal treatment or hip replacements in prostate cancer treatments, the extreme photon absorption by the metal object leads to prominent image artifacts...
March 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28319953/dual-versus-single-energy-ct-angiography-imaging-for-patients-undergoing-intracranial-aneurysm-repair
#3
Amr Abdulazim, Christian Rubbert, Dorothea Reichelt, Christian Mathys, Bernd Turowski, Hans-Jakob Steiger, Daniel Hänggi, Nima Etminan
BACKGROUND: The invasiveness and risk of thromboembolic complications of catheter angiography underline the need for alternative imaging modalities in patients following intracranial aneurysm (IA) repair. However, the overall image quality of existing noninvasive imaging modalities, such as single-energy CT angiography (SE-CTA), compromises its value in this respect. OBJECTIVE: We prospectively investigated the value of a novel dual-energy CTA (DE-CTA) scanner and algorithm for assessing the degree of occlusion and parent vessel patency in patients following IA repair...
March 21, 2017: Cerebrovascular Diseases
https://www.readbyqxmd.com/read/28319041/practical-use-of-a-plastic-scintillator-for-quality-assurance-of-electron-beam-therapy
#4
Katsunori Yogo, Yuya Tatsuno, Masato Tsuneda, Yuki Aono, Daiki Mochizuki, Yoshiki Fujisawa, Akihiro Matsushita, Minoru Ishigami, Hiromichi Ishiyama, Kazushige Hayakawa
Quality assurance (QA) of the clinical electron beam is essential for performing accurate and safe radiation therapy. However, with advances in radiation therapy, QA tends to be labor-intensive and time consuming. Here, we propose the practical use of a tissue-equivalent plastic scintillator for quick and easy QA of clinical electron beams. This tool enabled us to verify simultaneously the constancy of output, beam quality, depth and lateral dose profiles during monthly QAs at lower doses of irradiation (small MUs)...
March 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28317312/evaluation-of-dose-calculation-accuracy-of-treatment-planning-systems-at-hip-prosthesis-interfaces
#5
David Paulu, Parham Alaei
There are an increasing number of radiation therapy patients with hip prosthesis. The common method of minimizing treatment planning inaccuracies is to avoid radiation beams to transit through the prosthesis. However, the beams often exit through them, especially when the patient has a double-prosthesis. Modern treatment planning systems employ algorithms with improved dose calculation accuracies but even these algorithms may not predict the dose accurately at high atomic number interfaces. The current study evaluates the dose calculation accuracy of three common dose calculation algorithms employed in two commercial treatment planning systems...
March 20, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28317129/towards-robust-adaptive-radiation-therapy-strategies
#6
Michelle Böck, Anders Forsgren, Kjell Eriksson, Björn Hårdemark
PURPOSE: To set up a framework combining robust treatment planning with adaptive reoptimization in order to maintain high treatment quality, to respond to interfractional geometric variations and to identify those patients who will benefit the most from an adaptive fractionation schedule. METHODS: The authors propose robust adaptive strategies based on stochastic minimax optimization for a series of simulated treatments on a one-dimensional patient phantom. The plan applied during the first fractions should be able to handle anticipated systematic and random errors...
March 20, 2017: Medical Physics
https://www.readbyqxmd.com/read/28317122/an-anthropomorphic-abdominal-phantom-for-deformable-image-registration-accuracy-validation-in-adaptive-radiation-therapy
#7
Yuliang Liao, Linjing Wang, Xiangdong Xu, Haibin Chen, Jiawei Chen, Guoqian Zhang, Huaiyu Lei, Ruihao Wang, Shuxu Zhang, Xuejun Gu, Xin Zhen, Linghong Zhou
PURPOSE: To design and construct a three-dimensional (3D) anthropomorphic abdominal phantom for geometric accuracy and dose summation accuracy evaluations of deformable image registration (DIR) algorithms for adaptive radiation therapy (ART). METHOD: Organ molds, including liver, kidney, spleen, stomach, vertebra and two metastasis tumors, were 3D printed using contours from an ovarian cancer patient. The organ molds were molded with deformable gels made of different mixtures of polyvinyl chloride (PVC) and the softener dioctyl terephthalate...
March 20, 2017: Medical Physics
https://www.readbyqxmd.com/read/28314163/radon-measurements-and-dose-estimate-of-workers-in-a-manganese-ore-mine
#8
Amin Shahrokhi, Tamás Vigh, Csaba Németh, Anita Csordás, Tibor Kovács
In the new European Basic Safety Standard (EU-BSS), a new reference level for indoor radon concentration in workplaces has recommended that the annual average activity concentration of indoor radon shall not be higher than 300Bqm(-3). This paper describes the radon concentration level in an underground workplace (manganese ore mine) over long time intervals (4 years). Several common radon monitors devices - including NRPB and Raduet (as a passive method based on CR-39), AlphaGUARD PQ 2000Pro, SARAD EQF3220, TESLA and Pylon WLX (as active methods) - were used for continuous radon measurements...
March 10, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28314162/evaluation-of-the-distribution-of-activation-inside-a-compact-medical-cyclotron
#9
Toshioh Fujibuchi, Takatoshi Toyoda, Shingo Baba, Yoshiyuki Umezu, Isao Komiya, Masayuki Sasaki, Hiroshi Honda
The distribution of activation inside a compact medical cyclotron was evaluated by measuring 1cm dose equivalent rates and γ-ray spectra. Analysis of the distribution of activation showed high activation at the deflector and the magnetic channel. Radionuclides (60)Co, (57)Co, (65)Zn, and (54)Mn were detected. Different radionuclides were generated from different components of the cyclotron, and low-activity radionuclides could be detected under low-background-radiation conditions.
March 9, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28304221/fluoroscopy-time-is-not-accurate-as-a-surrogate-for-radiation-exposure
#10
Edvard Skripochnik, Shang A Loh
Objective The Food and Drug Administration and the Vascular Quality Initiative still utilize fluoroscopy time as a surrogate marker for procedural radiation exposure. This study demonstrates that fluoroscopy time does not accurately represent radiation exposure and that dose area product and air kerma are more appropriate measures. Methods Lower extremity endovascular interventions ( N = 145) between 2013 and 2015 performed at an academic medical center on a Siemens Artis-Zee floor mounted c-arm were identified...
January 1, 2017: Vascular
https://www.readbyqxmd.com/read/28303708/the-assessment-of-the-ionizing-radiation-dose-received-by-patients-during-some-diagnostic-x-ray-examinations-carried-out-on-the-basis-of-the-working-procedures-in-the-health-care-entities
#11
Marcin Bekas, Elżbieta Waśniewska, Adam Wardziński, Kamil Wieprzowski
Background: X-ray examination is a popular and universally used injury and disease diagnostic method. A distinctive X ray examination feature is that it can be done quickly which is extremely important in case of the need for rapid diagnosis of patients in life threatening condition. Another advantage of the X-ray examinations is also relatively low cost of carry. However, X-ray examination involve adverse health effects. During the examination the patient is subjected to ionizing radiation that might have impact on his health...
2017: Roczniki Państwowego Zakładu Higieny
https://www.readbyqxmd.com/read/28302493/the-risk-of-second-primary-cancers-due-to-peripheral-photon-and-neutron-doses-received-during-prostate-cancer-external-beam-radiation-therapy
#12
Eva Bezak, Rundgham Takam, Eric Yeoh, Loredana G Marcu
BACKGROUND: Out-of-field organs can be affected by secondary radiations originating from high energy linear accelerators, leading to an increased risk of carcinogenesis. The aim of this work was to determine the risk of second primary cancers (SPC) in the organs distal to the prostate during 3D conformal radiotherapy. MATERIALS AND METHODS: Based on previously measured peripheral photon and neutron doses in a Rando phantom using an 18MV photon beam, SPC risks in the out-of-field organs were estimated using the linear-no-threshold and the competitive risk models...
March 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28302144/a-dosimetric-model-for-the-heterogeneous-delivery-of-radioactive-nanoparticles-in-vivo-a-feasibility-study
#13
Andrew B Satterlee, Peter Attayek, Bentley Midkiff, Leaf Huang
ᅟ: Accurate and quantitative dosimetry for internal radiation therapy can be especially challenging, given the heterogeneity of patient anatomy, tumor anatomy, and source deposition. Internal radiotherapy sources such as nanoparticles and monoclonal antibodies require high resolution imaging to accurately model the heterogeneous distribution of these sources in the tumor. The resolution of nuclear imaging modalities is not high enough to measure the heterogeneity of intratumoral nanoparticle deposition or intratumoral regions, and mathematical models do not represent the actual heterogeneous dose or dose response...
March 17, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28302073/image-quality-improvement-using-model-based-iterative-reconstruction-in-low-dose-chest-ct-for-children-with-necrotizing-pneumonia
#14
Jihang Sun, Tong Yu, Jinrong Liu, Xiaomin Duan, Di Hu, Yong Liu, Yun Peng
BACKGROUND: Model-based iterative reconstruction (MBIR) is a promising reconstruction method which could improve CT image quality with low radiation dose. The purpose of this study was to demonstrate the advantage of using MBIR for noise reduction and image quality improvement in low dose chest CT for children with necrotizing pneumonia, over the adaptive statistical iterative reconstruction (ASIR) and conventional filtered back-projection (FBP) technique. METHODS: Twenty-six children with necrotizing pneumonia (aged 2 months to 11 years) who underwent standard of care low dose CT scans were included...
March 16, 2017: BMC Medical Imaging
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/28300383/dosimetry-analysis-of-panoramic-imaging-devices-in-different-sized-phantoms
#16
Muizz A Wahid, Ella Choi, David S MacDonald, Nancy L Ford
The aim of this study is to measure the radiographic dose in adult, adolescent, and child head-sized PMMA phantoms for three panoramic-imaging devices: the panoramic mode on two CBCT machines (Carestream 9300 and i-CAT NG) and the Planmeca ProMax 2D. A SEDENTEXCT dose index adult phantom and custom-built adolescent and pediatric PMMA dosimetry phantoms were used. Panoramic radiographs were performed using a Planmeca ProMax 2D and the panoramic mode on a Carestream 9300 CBCT and an i-CAT NG using the protocols used clinically...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28300380/dosimetric-characteristics-of-linatech-dmlc-h-multi-leaf-collimator-monte-carlo-simulation-and-experimental-study
#17
Mikaeil Molazadeh, Ahad Zeinali, Mostafa Robatjazi, Alireza Shirazi, Ghazale Geraily
This study evaluated the basic dosimetric characteristics of a Dynamic Multi Leaf Collimator (DMLC) using a diode detector and film measurements for Intensity Modulated Radiation Therapy Quality Assurance (IMRT QA). The EGSnrc Monte Carlo (MC) simulation system was used for the determination of MLC characteristics. Radiation transmission and abutting leaf leakage relevant to the LinaTech DMLC H were measured using an EDGE detector and EBT3 film. In this study, the BEAMnrc simulation code was used for modeling...
March 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28300369/perturbation-effects-of-the-carbon-fiber-peek-screws-on-radiotherapy-dose-distribution
#18
Alexander Nevelsky, Egor Borzov, Shahar Daniel, Raquel Bar-Deroma
Radiation therapy, in conjunction with surgical implant fixation, is a common combined treatment in cases of bone metastases. However, metal implants generally used in orthopedic implants perturb radiation dose distributions. Carbon-Fiber Reinforced Polyetheretherketone (CFR-PEEK) material has been recently introduced for production of intramedullary nails and plates. The purpose of this work was to investigate the perturbation effects of the new CFR-PEEK screws on radiotherapy dose distributions and to evaluate these effects in comparison with traditional titanium screws...
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
#19
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/28300363/activation-of-hip-prostheses-in-high-energy-radiotherapy-and-resultant-dose-to-nearby-tissue
#20
Stephanie Keehan, Ryan L Smith, Jeremy Millar, Max Esser, Michael L Taylor, Peta Lonski, Tomas Kron, Rick D Franich
High energy radiotherapy can produce contaminant neutrons through the photonuclear effect. Patients receiving external beam radiation therapy to the pelvis may have high-density hip prostheses. Metallic materials such as those in hip prostheses, often have high cross-sections for neutron interaction. In this study, Thackray (UK) prosthetic hips have been irradiated by 18 MV radiotherapy beams to evaluate the additional dose to patients from the activation products. Hips were irradiated in- and out-of field at various distances from the beam isocenter to assess activation caused in-field by photo-activation, and neutron activation which occurs both in and out-of-field...
March 2017: Journal of Applied Clinical Medical Physics
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