Results 141 to 150 of about 2,730 (174)

Inherent uncertainty of air kerma

Metrologia, 2013
Air kerma is defined in air, the constituents and the amounts of which are determined experimentally with some uncertainties. The inherent uncertainty of air kerma in a photon beam stemming from the uncertainties of atomic weights and composition data in air was evaluated as a function of photon energy.
openaire   +1 more source

Calibration and features of air-kerma length product meters

Radiation Protection Dosimetry, 2012
Pencil-type air-kerma length product meters are generally used for quality control and radiation exposure measurements in computed tomography. To ensure reliable results, these meters should be calibrated so that measurements are traceable to international standards.
K, Merimaa, M, Tapiovaara, A, Kosunen, P, Toroi   +3 more
openaire   +2 more sources

Significance and feasibility of air kerma length product and air kerma area product comparisons

Radiation Measurements
Air kerma length product and air kerma area product are special quantities used in diagnostic radiology. They are measured using special measurement devices – CT-chambers and KAP-meters, in order to calculate quantities related to patient exposure.
Miloš Živanović, Maja Vojnić Kortmiš, Nikola Kržanović, Miloš Đaletić, Ivana Komatina   +4 more
openaire   +2 more sources

Changes to the VNIIM air kerma primary standard

Metrologia, 2007
The result of extensive Monte Carlo calculations and a re-evaluation of the volume of the primary standard has led to an increase in the determination of air kerma at the VNIIM by 9.6 ? 10?3. The contributions to this change are summarized in this short note to announce that the VNIIM primary standard changed with effect from 1 November 2007.
I A Kharitonov, A V Oborin, A Y Villevalde   +2 more
openaire   +1 more source

Air kerma based dosimetry calibration for the Leksell Gamma Knife

Medical Physics, 2009
No accepted official protocol exists for the dosimetry of the Leksell Gamma Knife® (GK) stereotactic radiosurgery device. Establishment of a dosimetry protocol has been complicated by the unique partial‐hemisphere arrangement of 201 individual beams simultaneously focused on the treatment volume and by the rigid geometry of the GK unit itself.
Sheridan Griffin, Meltsner, Larry A, DeWerd   +1 more
openaire   +2 more sources

Calculation of air-kerma rate of diagnostic X-ray generators

Radiological Physics and Technology, 2010
As one type of basic physical data related to the calculation of the construction of X-ray examination room shielding, we investigated the air-kerma rate 1 m from the source of the useful beam focus per unit current time product. Compared to the X-ray energy penetration values obtained in prior research, we obtained higher values. We found three causes
Yoh, Katoh, Sogo, Mita, Masahiro, Fukushi, Yoshiyuki, Nyui, Shinji, Abe, Junichi, Kimura   +5 more
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Fluence non-uniformity effects in air kerma determination around brachytherapy sources

Physics in Medicine and Biology, 1997
In ionization chamber dosimetry close to brachytherapy sources, the non-uniform photon fluence in the vicinity of the air cavity of the ionization chamber must be corrected for. In this paper, experimentally determined relative non-uniformity correction factors are determined for a PTW23331 chamber and a number of Farmer-type chambers.
Tölli, H., Bielajew, A. F., Mattsson, O., Sernbo, G., Johansson, K. A.   +4 more
openaire   +3 more sources

New LMRI-CIEMAT primary standard for 137Cs air-kerma

Measurement, 2022
Abstract This paper presents the details and the characterization of two new graphite-walled cavity ionization chambers that will constitute the first Spanish national air-kerma standard for 137Cs. Physical constants and correction factors were determined according to the recent recommendations of the ICRU 90 report and the corresponding uncertainty ...
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Diaphragm correction factors for free-air chamber standards for air kerma in x-rays

Physics in Medicine & Biology, 2009
At present, only a correction factor for photon transmission, k l, is systematically applied for the entrance diaphragm of free-air chamber standards for air kerma. In the present work, the Monte Carlo code PENELOPE is used to re-evaluate k l for the BIPM standards and new correction factors are calculated for photon
D T, Burns, C, Kessler
openaire   +2 more sources

IAEA-SSDL bilateral comparisons for diagnostic level air kerma measurement standards

Physica Medica, 2018
Comparisons of national standard of air kerma for conventional and mammographic diagnostic X-ray radiation qualities were conducted by the IAEA. Eleven secondary standards dosimetry laboratories provided calibration data for Exradin A3 and Radcal RC6M transfer ionization chambers circulated.
István, Csete, Paula, Toroi, Andreas, Steuer, Costas, Hourdakis, Frantisek, Gabris, Sibusiso, Jozela, Antti, Kosunen, João, Cardoso, Vladimir, Sochor, Linda, Persson, Denis, Glavič Cindro, Mehenna, Arib, Mark, Smekhov   +12 more
openaire   +2 more sources