Evaluation of Dosimetric Characteristics of Reproducibility, Linearity and Dose Dependence of Optically Stimulated Luminescence Dosimeters in Co-60 Gamma-rays

Su Chul Han; Sang Hyoun Choi; Seungwoo Park; Chul Hang Kim; Haijo Jung; Mi-Sook Kim; Hyung Jun Yoo; Chan Hyeong Kim; Young Hoon Ji; Chul Young Yi; Kum Bae Kim

doi:10.14316/pmp.2014.25.1.31

Journal List > Prog Med Phys > v.25(1) > 1098457

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Han, Choi, Park, Kim, Jung, Kim, Yoo, Kim, Ji, Yi, and Kim: Evaluation of Dosimetric Characteristics of Reproducibility, Linearity and Dose Dependence of Optically Stimulated Luminescence Dosimeters in Co-60 Gamma-rays

Original Article

Progress in Medical Physics 2014;25(1):31-36.

Published online: 17 March 2014

DOI: https://doi.org/10.14316/pmp.2014.25.1.31

Evaluation of Dosimetric Characteristics of Reproducibility, Linearity and Dose Dependence of Optically Stimulated Luminescence Dosimeters in Co-60 Gamma-rays

Su Chul Han^∗,^†, Sang Hyoun Choi^†,^‡,^∥, Seungwoo Park^†, Chul Hang Kim^†, Haijo Jung^∗,^†, Mi-Sook Kim^∗,^†,^‡, Hyung Jun Yoo^†, Chan Hyeong Kim^∥, Young Hoon Ji^∗,^†, Chul Young Yi^§, Kum Bae Kim^∗,^†,^‡,

^∗Radiological Cancer Medicine, University of Science and Technology, Daejeon, Korea

^†Research Center for Radiotherapy, Korea Institute of Radiological and Medical Sciences, Seoul, Korea

^‡Department of Radiation Oncology, Korea Institute of Radiological and Medical Sciences, Seoul, Korea

^§Division of Methodology for Quality of Life, Korea Research Institute of Standards and Sciences, Daejeon, Korea

^∥Department of Nuclear Engineering, Hanyang University, Seoul, Korea

Correspondence:Kum Bae Kim (kbkim@kirams.re.kr) Tel: 82-2-970-2475, Fax: 82-2-970-2412

Received 28 January 2014 Accepted 16 March 2014

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We aimed to evaluate the dosimetric characteristics of reproducibility, linearity and dose dependence of optical stimulated luminance dosimeter (OSLD) in the Co-60 Gamma-rays and to analyze with a precedent study in field of the diagnostic radiography and radiotherapy. The reproducibility was 0.76% of the coefficient of variation, the homogeneity was within 1.5% of the coefficient of variation and OSLD had supra-linear response more than 3 Gy. So the correlation between dose and count was fitted by quadratic function. The count depletion by repeated reading was 0.04% per reading regardless of the irradiated dose. And the half time of decay curve according to the irradiated dose was 0.68 min. with 1 Gy, 1.04 min. with 5 Gy, and 1.10 min. with 10 Gy, respectively. In case of annealing for 30 min, the removal rate was 88% with 1 Gy, 90% with 5 Gy, and 92% with 10 Gy, respectively and 99% in case of annealing time for 4 hour. It is feasible to use OSLDs for dose evaluation in Co-60 Gamma-rays when considering the uncertainty on the procedure according to the irradiated dose.

Keywords: Optical stimulated luminance dosimeters, Dosimetric characteristics, Co-60

REFERENCES

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Fig. 1.

Decay time of the OSLD count rate (S(t)/S(t)_f) as a function of reading time after irradiating dose (1, 5, and 10 Gy). S(t) is the OSLD count at time t. S(t)_f is the OSLDs count at 1 min., after the irradiation. Each data point is the average response of three individual dosimeters.

Fig. 2.

The depletion of OSLD count when given sequential readings after irradiating dose (1, 5, and 10 Gy) OSLDs were irradiated to 1, 5, and 10 Gy of 60-Co Gamma- ray and Kept in the dark for 11 min, After the dark period, the OSLDs was read 50 times. The OSLD counts were normalized to value of the first reading (C_f).

Fig. 3.

OSLD response (count) Vs dose. The dose response of the OSLD with the absorbed dose was measured using three dosimeters that was same group. The nanodot was not optically annealed between irradiation.

Table 1.

Comparison of batch homogeneity before and after sampling measurement.

	Before sampling	After sampling
Average±S.D	72648±3400	72648±841
Range	From 63721 to 79336	From 70889 to 74760
Coefficient of variation (%)	4.68	0.92

Table 2.

Analysis of the decay of the OSLD count after irradiating with dose (1, 5, and 10 Gy).

Delivery dose	Factor about fitting equation (95% confidence bounds)
Delivery dose	A∗	B∗	K∗	T_1/2:0.693/k (min)	R²
1 Gy	0.739 (0.733∼0.745)	0.702 (0.592∼0.825)	1.014 (0.886∼1.140)	0.683 (0.607∼0.781)	0.993
5 Gy	0.857 (0.851∼0.863)	0.262 (0.207∼0.317)	0.660 (0.507∼0.813)	1.048 (0.851∼1.344)	0.985
10 Gy	0.900 (0.896∼0.903)	0.178 (0.145∼0.210)	0.626 (0.495∼0.757)	1.105 (0.914∼1.390)	0.988

^∗ The data were analyzed using equation (1).

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