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Moon, Rhee, Kim, Kang, Lee, Lim, and Jeong: Reference Dosimetry and Calibration of Glass Dosimeters for Cs-137 Gamma-rays
Original Article

Progress in Medical Physics 2013;24(3):140-144.

Published online: 17 September 2013

DOI: https://doi.org/10.14316/pmp.2013.24.3.140

Reference Dosimetry and Calibration of Glass Dosimeters for Cs-137 Gamma-rays

Young Min Moon†, Dong Joo Rhee∗, Jung Ki Kim∗, Yeong-Rok Kang∗, Man Woo Lee∗, Heuijin Lim∗, Dong Hyeok Jeong∗,

∗Research Center, Dongnam Inst. of Radiological & Medical Sciences, Busan, Korea

†Department of Materials Physics, Dong-A University, Busan, Korea

Corresponding Author: Dong Hyeok Jeong, Research Center, Dongnam Inst. of Radiological & Medical Sciences, 40, Jwadong-gil, Jangan-eup, Gijang-gun, Busan 619-953, KoreaTel: 051)720-5813, Fax: 051)720-5826E-mail: physics7@empal.com

Received 7 August 2013       Accepted 20 August 2013

Copyright © 2013 Korean Society of Medical Physics

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

In this research, the glass dosimeter was calibrated to measure the standard absorbed dose of the Cs-137 irradiator and absorbed dose in a biological sample. Absorbed dose in water for Cs-137 gamma ray was determined by the IAEA TRS-277 protocol. The PTW-TM30013 ion chamber and the PTW-TM41023 water phantom were utilized for measuring absorbed dose and the value was compared with the reading from DoseAce GD-302M glass dosimeter from Asahi Techno Glass Corporation for its calibration. The uncertainty of measurement (1σ) of the calibrated glass dosimeter was 2.7% and this result would be applied to improve the accuracy in measurement of absorbed dose in a biological sample.

Keywords: Cs-137 irradiator, TRS-277 protocol, Glass dosimeter

REFERENCES

1. Jeong DH, Kim JK, Yang KM, et al. Absorbed dose determination for a biological sample irradiated by gamma rays from a Cs-137 source. Korean J Med Phys. 22(3):124–130. 2011.
2. Sabine H. Methods in Radiobiology. Nanodosimetry Workshop. 2009.
3. Kwak DH, Moon YM, Kang YR, Lee CY, Jeong DH, Kim JK. 감마선 조사시 용기의 크기에 따른 흡수선량 평가. KARP 춘계학술대회 논문집. 2011, Seoul, pp.282.
4. Brady SL, Toncheva G, Dewhirst MW, Yoshizumi TT. Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools. Health Phys. 97(3):195–205. 2009.
crossref
5. TRS-277. Absorbed Dose Determination in Photon and Electron Beams: An International Code of Practice. International Atomic Energy Agency, Vienna. 1997.
6. TRS-398. Absorbed dose determination in external beam radiotherapy: an international code of practice for dosimetry based on standards of absorbed dose to water. International Atomic Energy Agency, Vienna. 2000.

Fig. 1.
A photography of geometrical setup for measuring absorbed dose to water for a Cs-137 gamma-ray irradiator.
pmp-24-140f1.tif
Fig. 2.
A glass dosimeter located at a depth in water using Markus chamber adaptor.
pmp-24-140f2.tif
Table 1.
Values for Cs-137 gamma rays in TRS-277 protocol, ∗kTP corrected.
Physical quantity Values for Cs-137 gamma rays
M (pC) 80.25∗00
NK (cGy/nC) 5.016
(1-g) 0.997
kmkatt 0.973
α 0.510
Sw,air 1.136
Swall, air 1.107
(en/ρ)w,wall 1.029
pu 1.001
pdis 0.988
Dose (mGy) 4.385
Dose (mGy/h) 26.1200
Table 2.
Dosimeter readings, its standard deviations, and calibration factors for 6 glass dosimeters.
  Gpre±SD (μGy-gr) Gread±SD (μGy-gr) R±SD (μGy-gr) Relative SD (%) of R Ni (mGy/mGy-gr)
1 720±1.89 4,755±9.46 4,035±9.64 0.23 1.086
2 712±1.27 4,752±8.20 4,040±8.30 0.20 1.085
3 704±1.90 4,702±8.99 3,998±9.19 0.22 1.097
4 704±1.87 4,700±9.62 3,996±9.80 0.24 1.097
5 706±1.10 4,785±9.39 4,079±9.45 0.23 1.075
6 687±1.83 4,713±7.76 4,026±7.97 0.20 1.089

Variation of glass dosimeters: 0.8%

Table 3.
Uncertainty estimations of calibration of the glass dosimeters in this study.
Type of physical quantity or procedure Estimated uncertainty
Applied value Relative (%)
Calibration factor of - 0.60
ion-chamber    
Measured charge - 0.50
Temperature correction 0.05oC 0.02
Pressure correction 0.01 kPa 0.01
Interaction coefficients in Eq.(1) - 2.60
Timer error 1 sec 0.02
Measured distance 1 mm 0.11
Reference dose from 2.70%
ion-chamber dosimetry    
Dosimeter reading - 0.24
(maximum)    
Holder positioning in water 1 mm 0.11
Dosimeter response from 0.26%
reader    
Total uncertainty 2.71%
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