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ionization chamber

Takuya Yabe, Masataka Komori, Toshiyuki Toshito, Mitsutaka Yamaguchi, Naoki Kawachi, Seiichi Yamamoto
Although the luminescence images of water during proton-beam irradiation using a cooled charge-coupled device (CCD) camera showed almost the same ranges of proton beams as those measured by an ionization chamber, the depth profiles showed lower Bragg peak intensities than those measured by an ionization chamber. In addition, a broad optical baseline signal was observed in depths that exceed the depth of Bragg peak. We hypothesize that this broad baseline signal originates from interaction of proton-induced prompt gamma photons with water...
January 19, 2018: Physics in Medicine and Biology
Bhupendra Singh Rana, Sanjeev Kumar, Inderjeet Singh Sandhu, Narinder Paul Singh
The present work reports dosimetry data on adult and pediatric patients for some common radiographic examinations during the standard hospital routine. The measurements are the part of quality assurance program to determine radiation exposures to patients in these examinations. The entrance skin doses (ESDs) of the patients were measured from 2451 projection for 12 diagnostic examinations in digital radiography (DR). The ESDs in adult patient were measured using thermoluminescence dosemeters placed on the skin of the patient...
January 12, 2018: Radiation Protection Dosimetry
Gregor Bruggmoser, Rainer Saum, Rafael Kranzer
The aim of this technical communication is to provide correction factors for recombination and polarity effect for two new ionization chambers PTW PinPoint 3D (type 31022) and PTW Semiflex 3D (type 31021). The correction factors provided are for the (based on the) German DIN 6800-2 dosimetry protocol and the AAPM TG51 protocol. The measurements were made in filtered and unfiltered high-energy photon beams in a water equivalent phantom at maximum depth of the PDD and a field size on the surface of 10cm×10cm...
January 11, 2018: Zeitschrift Für Medizinische Physik
Yoshiyuki Katsuta, Noriyuki Kadoya, Yukio Fujita, Eiji Shimizu, Kenichi Matsunaga, Kinya Sawada, Haruo Matsushita, Kazuhiro Majima, Keiichi Jingu
Log file-based methods are attracting increasing interest owing to their ability to validate volumetric-modulated arc therapy outputs with high resolution in the leaf and gantry positions and in delivered dose. Cross-validation of these methods for comparison with measurement-based methods using the ionization chamber/ArcCHECK-3DVH software (version 3.2.0) under the same conditions of treatment anatomy and plan enables an efficient evaluation of this method. In this study, with the purpose of cross-validation, we evaluate the accuracy of a log file-based method using Elekta log files and an X-ray voxel Monte Carlo dose calculation technique in the case of leaf misalignment during prostate volumetric-modulated arc therapy...
December 2017: Technology in Cancer Research & Treatment
Jhy-Charm Soo, Eun Gyung Lee, Ryan F LeBouf, Michael L Kashon, William Chisholm, Martin Harper
The objective of this present study was to evaluate the performance of a portable gas chromatograph ─ photoionization detector (GC-PID), under various test conditions to determine if it could be used in occupational settings. A mixture of seven volatile organic compounds (VOCs) - acetone, ethylbenzene, methyl isobutyl ketone, toluene, m-xylene, p-xylene, and o-xylene - was selected because its components are commonly present in paint manufacturing industries. A full-factorial combination of four concentration levels (exposure scenarios) of VOC mixtures, three different temperatures (25˚C, 30˚C, and 35˚C), and three relative humidities (RHs; 25%, 50%, and 75%) was conducted in a full- size controlled environmental chamber...
January 15, 2018: Journal of Occupational and Environmental Hygiene
Achim Krauss, Ralf-Peter Kapsch
For the ionometric determination of the absorbed dose to water, Dw, in high-energy electron beams from a clinical accelerator, beam quality dependent correction factors, kQ, are required. By using a water calorimeter, these factors can be determined experimentally and potentially with lower standard uncertainties than those of the calculated kQ factors, which are tabulated in various dosimetry protocols. However, one of the challenges of water calorimetry in electron beams is the small measurement depths in water, together with the steep dose gradients present especially at lower energies...
January 12, 2018: Physics in Medicine and Biology
Dennis Rottke, Lisa Gohlke, Robert Schrödel, Stefan Hassfeld, Dirk Schulze
OBJECTIVES: The present study aims at investigating different radiation protection issues and dose values while acquiring intraoral images with a handheld X-ray device. METHODS: An Aribex NOMAD Pro 2TM, a RANDO® male head phantom, a consistency testing body (CTB), a PTW NOMEX® Multimeter, and a PTW Farmer® Ionization Chamber Type 30010 were used to investigate: (1) dose area products (DAP); (2) the expansion of the control area (CA); (3) the scattering pattern; and (4) the potential risk for operators of the X-ray device...
January 10, 2018: Dento Maxillo Facial Radiology
Xiaoyong Wang, Lixin Chen, Conghua Xie, Dajiang Wang, Gaili Chen, Zhengming Fu, Hui Liu
Purpose: To evaluate the Edose system, a novel three-dimensional (3D) in vivo dose monitoring system based on electronic portal imaging device (EPID), prior to clinical application, we analyzed the preliminary clinical data using Edose system in patients receiving intensity-modulated radiation therapy (IMRT). Materials and methods: After the physical modeling, the measured results from the Edose system were examined in homogeneous and inhomogeneous phantoms, respectively...
December 12, 2017: Oncotarget
S Becker, N Raatz, St Jankuhn, R John, J Meijer
Established techniques for ion implantation rely on technically advanced and costly machines like particle accelerators that only few research groups possess. We report here about a new and surprisingly simple ion implantation method that is based upon a widespread laboratory instrument: The scanning electron microscope. We show that it can be utilized to ionize atoms and molecules from the restgas by collisions with electrons of the beam and subsequently accelerate and implant them into an insulating sample by the effect of a potential building up at the sample surface...
January 8, 2018: Scientific Reports
Takahiro Ushigusa, Yoshiyuki Koyama, Tomoko Ito, Kenichi Watanabe, James K Chambers, Aya Hasegawa, Kazuyuki Uchida, Ryoji Kanegi, Shingo Hatoya, Toshio Inaba, Kikuya Sugiura
By using a complex of DNA, polyethylenimine and chondroitin sulfate, the in vivo transfection of early secretory antigenic target-6 (ESAT-6) gene into tumor cells was found to cause significant suppression of the tumor growth. In order to apply the method in clinical cancer treatment in dogs and cats, mechanisms underlying the suppressive effects were investigated in a tumor-bearing mouse model. The transfection efficiency was only about 10%, but the transfection of ESAT-6 DNA nevertheless induced systemic immune responses against ESAT-6...
January 1, 2018: Journal of Veterinary Medical Science
Thomas S Thompson, Johan P van den Heever, Stephen F Pernal
Dicyclohexylamine (DCH) is an excipient present in commercial formulations of fumagillin (Fumagilin-B® and Fumidil-B®), an antibiotic which is employed in apiculture for the control of nosema disease. DCH has been demonstrated to be stable in harvested honey; however, its fate in the beehive has not been investigated. In this study, DCH residues were determined in beeswax samples collected from brood chambers and honey supers from various apiaries throughout Alberta. The determination of DCH was performed using a simple extraction procedure followed by low-temperature cleanup and finally analysis with aqueous normal phase liquid chromatography-electrospray ionization tandem mass spectrometry...
December 29, 2017: Journal of Chromatographic Science
Prabhakar Ramachandran, Abdulrahman Tajaldeen, David Taylor, Derrick Wanigaratne, Karl Roozen, Moshi Geso
Aim: The aim of this study is to assess the use of ArcCHECK (AC) as an alternative method to replace film dosimetry for pre-treatment quality assurance (QA) of three-dimensional conformal radiation therapy, intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) stereotactic ablative radiotherapy (SABR) treatment plans. Materials and Methods: Twenty-five patients with a varied diagnosis of lung, spine, sacrum, sternum, ribs, scapula, and femur undergoing SABR were selected for this study...
October 2017: Journal of Medical Physics
Somayeh Gholami, Hassan Ali Nedaie, Francesco Longo, Mohammad Reza Ay, Sharifeh A Dini, Ali S Meigooni
Purpose: The clinical efficacy of Grid therapy has been examined by several investigators. In this project, the hole diameter and hole spacing in Grid blocks were examined to determine the optimum parameters that give a therapeutic advantage. Methods: The evaluations were performed using Monte Carlo (MC) simulation and commonly used radiobiological models. The Geant4 MC code was used to simulate the dose distributions for 25 different Grid blocks with different hole diameters and center-to-center spacing...
October 2017: Journal of Medical Physics
L Ben Salem, A Essadok, I Saidani, M Mahdouani, M Benna, K Mahjoubi, M Besbes, F Benna
PURPOSE: The aim of this work is to determine experimentally the correction factors [Formula: see text] for four active commercial dosimeters: two microchambers and two diode detectors based on the output factor measured with radiochromic film for a radiotherapy linear accelerator equipped with circular cones. MATERIALS AND METHODS: Initially, a radiochromic film dosimetry measurement protocol with an accuracy of 2% was developed to approach the "reference output factor"...
December 28, 2017: Cancer Radiothérapie: Journal de la Société Française de Radiothérapie Oncologique
N A Garkava, P A Fedirko, T F Babenko, R E Dorichevska
OBJECTIVE: Estimate changes blood filling of the ciliary body and changes of the anterior chamber angle; study their influence to glaucoma pathogenesis in irradiated persons. MATERIALS AND METHODS: Used the results of a randomly selected group survey of 41 clean up workers of the Chornobyl NPP accident (clean up workers), and 18 inhabitants of the zone of guaranteed voluntary resettlement; age at the time of the survey was 45-50 years. The control group consisted of 41 persons of the same age had not radiation exposure...
December 2017: Problemy Radiat︠s︡iĭnoï Medyt︠s︡yny Ta Radiobiolohiï
I Z Russu, N K Rodionova, D I Bilko, N M Bilko
Under the influence of ionizing radiation on hematopoietic system, the level of its injury is determined not only by the radiosensitivity of hematopoietic stem cells, but also by radiation induced changes in microenvironment func tioning, in particular, mesenchymal stem cells as its components. OBJECTIVE: to define functioning characteristics of mesenchymal stem and progenitor cells of rats' bone marrow under prolonged action of ionizing radiation as a result of 90Sr incorporation. MATERIALS AND METHODS: We applied the model of Wistar rats' internal irradiation with 90Sr radionuclide and per formed the in vitro cultivation of their bone marrow mesenchymal cells...
December 2017: Problemy Radiat︠s︡iĭnoï Medyt︠s︡yny Ta Radiobiolohiï
Seyed Mostafa Mohammadi, Hossein Tavakoli-Anbaran
A free-air ionization chamber FAC-IR-300, designed by the Atomic Energy Organization of Iran, is used as the primary Iranian national standard for the photon air kerma. For accurate air kerma measurements, the contribution from the scattered photons to the total energy released in the collecting volume must be eliminated. One of the sources of scattered photons is the chamber's diaphragm. In this paper, the diaphragm scattering correction factor, kdia, and the diaphragm transmission correction factor, ktr, were introduced...
November 28, 2017: Applied Radiation and Isotopes
Akira Yunoki, Yasushi Kawada, Yoshio Hino
We developed a new method to determine the response ratio of an ionization chamber (Ohkura ionization chamber: type I-4096 01/06) filled with dry air to that filled with P-10 gas. The response-ratio was obtained by comparing the output currents of the ionization chamber after introduction of radioactive gasses of identical activities contained in two small vessels. The obtained ratio was 0.690 ± 0.003, which agreed with the results obtained by other methods.
November 13, 2017: Applied Radiation and Isotopes
Victor N Malkov, David W O Rogers
PURPOSE: To use EGSnrc Monte Carlo simulations for magnetic field dosimetry to determine optimal measurement orientations, calculate beam quality conversion factors for 32 cylindrical and three parallel-plate (PP) ion chambers, evaluate the beam quality and angular dependence of these factors, and examine the magnetic field effects on %dd(10)x and TPR1020 METHODS: Beam quality conversion factors,kQmag, and magnetic field conversion factors, kB=kQmag/kQ , are calculated as a function of chamber rotation for six cylindrical ionization chamber and either a 60 Co beam with a 0...
December 7, 2017: Medical Physics
Maud Jaccard, Maria Teresa Durán, Kristoffer Petersson, Jean-François Germond, Philippe Liger, Marie-Catherine Vozenin, Jean Bourhis, François Bochud, Claude Bailat
PURPOSE: The Oriatron eRT6 is an experimental high dose-per-pulse linear accelerator (linac) which was designed to deliver an electron beam with variable dose-rates, ranging from a few Gy/min up to hundreds of Gy/s. It was built to study the radiobiological effects of high dose-per-pulse/dose-rate electron beam irradiation, in the context of preclinical and cognitive studies. In this work, we report on the commissioning and beam monitoring of the Oriatron eRT6 prototype linac. MATERIALS AND METHODS: The beam was characterized in different steps...
December 5, 2017: Medical Physics
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