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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Evaluation of conversion coefficients relating air-kerma to H-star(10) using primary and transmitted x-ray spectra in the diagnostic radiology energy range

Full text
Author(s):
Santos, J. C. [1] ; Mariano, L. [1] ; Tomal, A. [2] ; Costa, P. R. [1]
Total Authors: 4
Affiliation:
[1] Univ Sao Paulo, Inst Fis, BR-05508 Sao Paulo - Brazil
[2] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13081970 Campinas, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: JOURNAL OF RADIOLOGICAL PROTECTION; v. 36, n. 1, p. 117-132, MAR 2016.
Web of Science Citations: 2
Abstract

According to the International Commission on Radiation Units and Measurements (ICRU), the relationship between effective dose and incident air-kerma is complex and depends on the attenuation of x-rays in the body. Therefore, it is not practical to use this quantity for shielding design purposes. This correlation is adopted in practical situations by using conversion coefficients calculated using validated mathematical models by the ICRU. The ambient dose equivalent, H{*}(10), is a quantity adopted by the IAEA for monitoring external exposure. Dose constraint levels are established in terms of H{*}(10), while the radiation levels in radiometric surveys are calculated by means of the measurements of air-kerma with ion chambers. The resulting measurements are converted into ambient dose equivalents by conversion factors. In the present work, an experimental study of the relationship between the air-kerma and the operational quantity ambient dose equivalent was conducted using different experimental scenarios. This study was done by measuring the primary x-ray spectra and x-ray spectra transmitted through materials used in dedicated chest radiographic facilities, using a CdTe detector. The air-kerma to ambient dose equivalent conversion coefficients were calculated from these measured spectra. The resulting values of the quantity ambient dose equivalent using these conversion coefficients are more realistic than those available in the literature, because they consider the real energy distribution of primary and transmitted x-ray beams. The maximum difference between the obtained conversion coefficients and the constant value recommended in national and international radiation protection standards is 53.4%. The conclusion based on these results is that a constant coefficient may not be adequate for deriving the ambient dose equivalent. (AU)

FAPESP's process: 11/04721-9 - Experimental approach for the relation between air-kerma and ambient equivalent dose for shielding calculation of primary barriers of X-ray imaging facilities
Grantee:Josilene Cerqueira Santos
Support Opportunities: Scholarships in Brazil - Master
FAPESP's process: 10/12237-7 - Experimento evaluation of the relation between air-Kerma and ambient equivalent dose for shielding calculation in adult and pediatric X-ray rooms
Grantee:Paulo Roberto Costa
Support Opportunities: Regular Research Grants