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Dosimetry

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https://www.readbyqxmd.com/read/28742424/evaluation-of-noise-exposure-secondary-to-wind-noise-in-cyclists
#1
Michael D Seidman, Anna G Wertz, Matthew M Smith, Steve Jacob, Syed F Ahsan
Objective Determine if the noise levels of wind exposure experienced by cyclists reach levels that could contribute to noise-induced hearing loss. Study Design Industrial lab research. Setting Industrial wind tunnel. Subjects and Methods A commercial-grade electric wind tunnel was used to simulate different speeds encountered by a cyclist. A single cyclist was used during the simulation for audiometric measurements. Microphones attached near the ears of the cyclist were used to measure the sound (dB sound pressure level) experienced by the cyclist...
July 1, 2017: Otolaryngology—Head and Neck Surgery
https://www.readbyqxmd.com/read/28742061/test-study-of-boron-nitride-as-a-new-detector-material-for-dosimetry-in-high-energy-photon-beams
#2
Daniela Poppinga, Jannik Halbur, Sarah Lemmer, Bjoern Delfs, Dietrich Harder, Hui Khee Looe, Bjoern Poppe
The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high energy photon-beam dosimetry. Boron nitride is a compound of boron and nitrogen and exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its atomic constituents, its density (2...
July 25, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28736826/impact-of-respiratory-motion-and-acquisition-settings-on-spect-liver-dosimetry-for-radioembolization
#3
Remco Bastiaannet, Max A Viergever, Hugo W A M de Jong
PURPOSE: Respiratory motion may impose significant inaccuracies on emission activity estimation in quantitative SPECT. This effect may be a major issue in dosimetry as used in management of liver radioembolization. The purpose of this study was to investigate the impact of respiratory motion on radioembolization liver dosimetry for different SPECT acquisition settings. METHODS: In a series of SPECT/CT Monte Carlo simulations using several digital XCAT phantoms, the following parameters were varied: breathing/non-breathing, liver tumor size (0...
July 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28736283/multicellular-dosimetric-chain-for-molecular-radiotherapy-exemplified-with-dose-simulations-on-3d-cell-spheroids
#4
Vappu Reijonen, Liisa K Kanninen, Eero Hippeläinen, Yan-Ru Lou, Eero Salli, Alexey Sofiev, Melina Malinen, Timo Paasonen, Marjo Yliperttula, Antti Kuronen, Sauli Savolainen
PURPOSE: Absorbed radiation dose-response relationships are not clear in molecular radiotherapy (MRT). Here, we propose a voxel-based dose calculation system for multicellular dosimetry in MRT. We applied confocal microscope images of a spherical cell aggregate i.e. a spheroid, to examine the computation of dose distribution within a tissue from the distribution of radiopharmaceuticals. METHODS: A confocal microscope Z-stack of a human hepatocellular carcinoma HepG2 spheroid was segmented using a support-vector machine algorithm and a watershed function...
July 20, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28735877/dose-comparison-between-tg-43-based-calculations-and-radiochromic-film-measurements-of-the-freiburg-flap-applicator-used-for-high-dose-rate-brachytherapy-treatments-of-skin-lesions
#5
Saad Aldelaijan, Hamed Bekerat, Ivan Buzurovic, Phillip Devlin, Francois DeBlois, Jan Seuntjens, Slobodan Devic
PURPOSE: Current high-dose-rate brachytherapy skin treatments with the Freiburg flap (FF) applicator are planned with treatment planning systems based on the American Association of Physicists in Medicine TG-43 data sets, which assume full backscatter conditions in dose calculations. The aim of this work is to describe an experimental method based on radiochromic film dosimetry to evaluate dose calculation accuracy during surface treatments with the FF applicator at different depths and bolus thicknesses...
July 20, 2017: Brachytherapy
https://www.readbyqxmd.com/read/28735112/evaluation-of-the-accuracy-of-mono-energetic-electron-and-beta-emitting-isotope-dose-point-kernels-using-particle-and-heavy-ion-transport-code-system-phits
#6
Takuro Shiiba, Naoya Kuga, Yasuyoshi Kuroiwa, Tatsuhiko Sato
We assessed the accuracy of mono-energetic electron and beta-emitting isotope dose-point kernels (DPKs) calculated using the particle and heavy ion transport code system (PHITS) for patient-specific dosimetry in targeted radionuclide treatment (TRT) and compared our data with published data. All mono-energetic and beta-emitting isotope DPKs calculated using PHITS, both in water and compact bone, were in good agreement with those in literature using other MC codes. PHITS provided reliable mono-energetic electron and beta-emitting isotope scaled DPKs for patient-specific dosimetry...
July 15, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28732021/in-vitro-comparison-of-213bi-and-177lu-radiation-for-peptide-receptor-radionuclide-therapy
#7
Ho Sze Chan, Erik de Blois, Alfred Morgenstern, Frank Bruchertseifer, Marion de Jong, Wouter Breeman, Mark Konijnenberg
BACKGROUND: Absorbed doses for α-emitters are different from those for β-emitters, as the high linear energy transfer (LET) nature of α-particles results in a very dense energy deposition over a relatively short path length near the point of emission. This highly localized and therefore high energy deposition can lead to enhanced cell-killing effects at absorbed doses that are non-lethal in low-LET type of exposure. Affinities of DOTA-DPhe1-Tyr3-octreotate (DOTATATE), 115In-DOTATATE, 175Lu-DOTATATE and 209Bi-DOTATATE were determined in the K562-SST2 cell line...
2017: PloS One
https://www.readbyqxmd.com/read/28731074/left-hippocampus-sparing-whole-brain-radiotherapy-wbrt-a-planning-study
#8
Tomas Kazda, Miroslav Vrzal, Tomas Prochazka, Petr Dvoracek, Petr Burkon, Petr Pospisil, Adam Dziacky, Tomas Nikl, Radim Jancalek, Pavel Slampa, Radek Lakomy
AIMS: Unilateral sparing of the dominant (left) hippocampus during whole brain radiotherapy (WBRT) could mitigate cognitive decline, especially verbal memory, similar to the widely investigated bilateral hippocampus avoidance (HA-WBRT). The aim of this planning study is dosimetrical comparison of HA-WBRT with only left hippocampus sparing (LHA-WBRT) plans. METHODS: HA-WBRT plans for 10 patients were prepared in accordance with RTOG 0933 trial and served as baseline for comparisons with several LHA-WBRT plans prepared with an effort: 1) to maintain the same left hippocampus dosimetry ("BEST PTV") and 2) to maintain same dosimetry in planning target volume as in HA-WBRT ("BEST LH")...
July 20, 2017: Biomedical Papers of the Medical Faculty of the University Palacký, Olomouc, Czechoslovakia
https://www.readbyqxmd.com/read/28730652/effects-of-collimator-angle-couch-angle-and-starting-phase-on-motion-tracking-dynamic-conformal-arc-therapy-4d-dcat
#9
Zhengzheng Xu, Rutao Yao, Matthew B Podgorsak, Iris Z Wang
PURPOSE: The aim of this study was to find an optimized configuration of collimator angle, couch angle, and starting tracking phase to improve the delivery performance in terms of MLC position errors, maximal MLC leaf speed, and total beam-on time of DCAT plans with motion tracking (4D DCAT). METHOD AND MATERIALS: Nontracking conformal arc plans were first created based on a single phase (maximal exhalation phase) of a respiratory motion phantom with a spherical target...
July 21, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28728135/prostate-cancer-risk-and-dna-methylation-signatures-in-aging-rats-following-developmental-bpa-exposure-a-dose-response-analysis
#10
Gail S Prins, Shu-Hua Ye, Lynn Birch, Xiang Zhang, Ana Cheong, Han Lin, Esther Calderon-Gierszal, Jacob Groen, Wen-Yang Hu, Shuk-Mei Ho, Richard B van Breemen
BACKGROUND: Previous studies have uncovered heightened prostatic susceptibility to hormone-induced neoplasia from early-life exposure to low-dose bisphenol A (BPA). However, significant data gaps remain that are essential to address for biological relevance and necessary risk assessment. OBJECTIVES: A complete BPA dose-response analysis of prostate lesions across multiple prostatic lobes was conducted that included internal BPA dosimetry, progression to adenocarcinoma with aging and mechanistic connections to epigenetically reprogramed genes...
July 11, 2017: Environmental Health Perspectives
https://www.readbyqxmd.com/read/28726679/accuracy-of-rhenium-188-spect-ct-activity-quantification-for-applications-in-radionuclide-therapy-using-clinical-reconstruction-methods
#11
Pedro L Esquinas, Carlos F Uribe, M Gonzalez, Cristina Rodríguez-Rodríguez, Urs O Häfeli, Anna Celler
The main applications of (188)Re in radionuclide therapies include trans-arterial liver radioembolization and palliation of painful bone-metastases. In order to optimize (188)Re therapies, the accurate determination of radiation dose delivered to tumors and organs at risk is required. Single photon emission computed tomography (SPECT) can be used to perform such dosimetry calculations. However, the accuracy of dosimetry estimates strongly depends on the accuracy of activity quantification in (188)Re images...
July 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28725246/effects-of-vaginal-cylinder-position-on-dose-distribution-in-patients-with-endometrial-carcinoma-in-treatment-of-vaginal-cuff-brachytherapy
#12
Yurday Ozdemir, Yemliha Dolek, Cem Onal
PURPOSE: To investigate the impact of different cylinder positions on dosimetry of critical structures in patients with endometrial carcinoma undergoing three-dimensional image-based vaginal cuff brachytherapy (VCB). MATERIAL AND METHODS: We delivered VCB at a dose of 4 Gy to a depth of 5 mm in the vaginal cuff of 15 patients using three different cylinder positions (neutral [N], parallel [P], and angled [A]) according to the longitudinal axis of the patient. We analyzed the dose-volume distribution and volumetric variability of the rectum and bladder...
June 2017: Journal of Contemporary Brachytherapy
https://www.readbyqxmd.com/read/28724867/evaluation-of-the-patient-exposure-in-general-radiography-for-some-facilities-comparison-with-drl-and-evaluation-of-the-difference-among-facilities
#13
Koji Ono, Yuya Kondo, Takuma Ichikawa, Yasuki Asada
The first diagnostic reference levels (DRLs 2015) in Japan were published in June 2015. The purpose of this study was to compare the calculated entrance surface doses with the values of DRLs 2015, and evaluate differences in patient exposure among facilities. Semiconductor dosimeter was installed, and dosimetry was performed using equipment and radiographic condition of each facility. As a result, a dose higher than the value of DRLs 2015 was used in 12 kinds of examination. In child chest examination, the doses of the three facilities (0...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28723715/novel-weight-based-dose-threshold-for-18f-naf-pet-ct-imaging-using-advanced-pet-ct-systems-a-potential-tool-for-reducing-radiation-burden
#14
Fahad Marafi, Abdulreda Esmail, Rashid Rasheed, Fareeda Alkandari, Sharjeel Usmani
BACKGROUND: Fluorine-18-sodium fluoride (F-NaF) PET/CT is an important tool for detecting and evaluating metastatic bone cancer. Besides traditional dose metrics, recent methods such as real-time dose mapping, dose calculation from DICOM information, and their relevance to entrance skin exposure are currently in use to reduce the radiation burden. In this study, we have analyzed the data of 1062 patients retrospectively to evaluate patterns of absorbed dose for institutional weight-based dose protocol as compared with fixed dose method guidelines of Society of Nuclear Medicine and Molecular Imaging (SNMMI)...
July 18, 2017: Nuclear Medicine Communications
https://www.readbyqxmd.com/read/28723274/identifying-voxels-at-risk-for-progression-in-glioblastoma-based-on-dosimetry-physiologic-and-metabolic-mri
#15
Mekhail Anwar, Annette M Molinaro, Olivier Morin, Susan M Chang, Daphne A Haas-Kogan, Sarah J Nelson, Janine M Lupo
Despite the longstanding role of radiation in cancer treatment and the presence of advanced, high-resolution imaging techniques, delineation of voxels at-risk for progression remains purely a geometric expansion of anatomic images, missing subclinical disease at risk for recurrence while treating potentially uninvolved tissue and increasing toxicity. This remains despite the modern ability to precisely shape radiation fields. A striking example of this is the treatment of glioblastoma, a highly infiltrative tumor that may benefit from accurate identification of subclinical disease...
July 19, 2017: Radiation Research
https://www.readbyqxmd.com/read/28721904/treatment-planning-system-calculation-errors-are-present-in-most-imaging-and-radiation-oncology-core-houston-phantom-failures
#16
James R Kerns, Francesco Stingo, David S Followill, Rebecca M Howell, Adam Melancon, Stephen F Kry
PURPOSE: The anthropomorphic phantom program at the Houston branch of the Imaging and Radiation Oncology Core (IROC-Houston) is an end-to-end test that can be used to determine whether an institution can accurately model, calculate, and deliver an intensity modulated radiation therapy dose distribution. Currently, institutions that do not meet IROC-Houston's criteria have no specific information with which to identify and correct problems. In the present study, an independent recalculation system was developed to identify treatment planning system (TPS) calculation errors...
August 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28721895/late-cardiac-toxicity-after-mediastinal-radiation-therapy-for-hodgkin-lymphoma-contributions-of-coronary-artery-and-whole-heart-dose-volume-variables-to-risk-prediction
#17
Ezra Hahn, Haiyan Jiang, Angela Ng, Shaheena Bashir, Sameera Ahmed, Richard Tsang, Alexander Sun, Mary Gospodarowicz, David Hodgson
PURPOSE: Mediastinal radiation therapy (RT) for Hodgkin lymphoma (HL) is associated with late cardiotoxicity, but there are limited data to indicate which dosimetric parameters are most valuable for predicting this risk. This study investigated which whole heart dosimetric measurements provide the most information regarding late cardiotoxicity, and whether coronary artery dosimetry was more predictive of this outcome than whole heart dosimetry. METHODS AND MATERIALS: A random sample of 125 HL patients treated with mediastinal RT was selected, and 3-dimensional cardiac dose-volume data were generated from historical plans using validated methods...
August 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28721684/pharmacokinetics-microscale-distribution-and-dosimetry-of-alpha-emitter-labeled-anti-pd-l1-antibodies-in-an-immune-competent-transgenic-breast-cancer-model
#18
Jessie R Nedrow, Anders Josefsson, Sunju Park, Tom Bäck, Robert F Hobbs, Cory Brayton, Frank Bruchertseifer, Alfred Morgenstern, George Sgouros
BACKGROUND: Studies combining immune checkpoint inhibitors with external beam radiation have shown a therapeutic advantage over each modality alone. The purpose of these works is to evaluate the potential of targeted delivery of high LET radiation to the tumor microenvironment via an immune checkpoint inhibitor. METHODS: The impact of protein concentration on the distribution of (111)In-DTPA-anti-PD-L1-BC, an (111)In-antibody conjugate targeted to PD-L1, was evaluated in an immunocompetent mouse model of breast cancer...
December 2017: EJNMMI Research
https://www.readbyqxmd.com/read/28720474/nitrous-oxide-cryotherapy-for-treatment-of-esophageal-squamous-cell-neoplasia-initial-multicenter-international-experience-with-a-novel-portable-cryoballoon-ablation-system-with-video
#19
Marcia Irene Canto, Julian Abrams, Hannah Kunzli, Bas Weusten, Yoshihiro Komatsu, Blair Jobe, Charles J Lightdale
BACKGROUND AND AIMS: Early esophageal squamous cell neoplasia (ESCN) can be successfully treated by endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), or radiofrequency ablation (RFA). A new portable, battery-powered cryotherapy system using nitrous oxide (cryoballoon focal ablation system (CbFAS) has been used for Barrett's esophagus. It consists of a small hand-held device containing liquid nitrous oxide, which converts to gas within a low-pressure-compliant through-the-scope balloon and freezes targeted mucosa in contact with the balloon...
July 15, 2017: Gastrointestinal Endoscopy
https://www.readbyqxmd.com/read/28719019/initial-testing-of-a-pixelated-silicon-detector-prototype-in-proton-therapy
#20
Andrew J Wroe, Grant McAuley, Anthony V Teran, Jeannie Wong, Marco Petasecca, Michael Lerch, James M Slater, Anatoly B Rozenfeld
As technology continues to develop, external beam radiation therapy is being employed, with increased conformity, to treat smaller targets. As this occurs, the dosimetry methods and tools employed to quantify these fields for treatment also have to evolve to provide increased spatial resolution. The team at the University of Wollongong has developed a pixelated silicon detector prototype known as the dose magnifying glass (DMG) for real-time small-field metrology. This device has been tested in photon fields and IMRT...
July 18, 2017: Journal of Applied Clinical Medical Physics
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