Title: The Monte Carlo simulation of the TLD response function: scattered radiation field application

Authors: Seied Rabie Mahdavi, Alireza Shirazi, Ali Khodadadee, Mostafa Ghafoori, Asghar Mesbahi

Addresses: Department of Biophysics-Biochemistry, Babol University of Medical Sciences, Babol, Iran. ' Department of Biophysics, Faculty of Medicine, Medical Sciences, University of Tehran, Iran. ' Azad Research and Science University, Tehran, Iran. ' Atomic Energy Organization of Iran (AEOI), Nuclear Science and Technology Research Institute, Karaj, Iran. ' Department of Medical School, Tabriz University of Medical Science, Tabriz, Iran

Abstract: Thermoluminescent Dosimeters (TLDs) have various applications in nonprimary beam dosimetry. The Monte Carlo simulation of the TLD response was done in low energy beams to improve its clinical use in scattered beam dosimetry. The normalised values of the measured quality dependence factors for different X-ray beams were found to be 1.28, 1.24, 1.16, 1.07 and 1.03 for different beam qualities, respectively. Comparatively, the Monte Carlo for |n| Particles (MCNP) simulated findings were 1.134, 1.96, 1.139, 1.052 and 1.034. The change of the calibration factor with energy follows the equation CF = B0 + B1E + B2E² + B3E³, where CF and E are the calibration factor and energy (keV), respectively, and B0, B1, B2 and B3 are the constants. Our findings show a significant deviation of the true dose value when the TLDs are calibrated at different beam qualities. The greatest deviation was 19.9 ± 2.1% with a beam quality of 120 kVp. Obtaining a dose-response curve may be helpful in calculating the calibration factor with more precision.

Keywords: TLD response; thermoluminescent dosimeters; calibration; quality dependence; Monte Carlo simulation; MCNP; scattered radiation; low radiation; scattered beam dosimetry.

DOI: 10.1504/IJLR.2008.019917

International Journal of Low Radiation, 2008 Vol.5 No.2, pp.124 - 133

Published online: 15 Aug 2008 *

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