Journal List > Prog Med Phys > v.25(3) > 1098431

TOOLS
Kang, Rhee, Kang, Kim, and Jeong: Determination of TRS-398 Quality Factors for Cs-137 Gamma Rays in Reference Dosimetry
Original Article

Progress in Medical Physics 2014;25(3):123-127.

Published online: 20 September 2014

DOI: https://doi.org/10.14316/pmp.2014.25.3.123

Determination of TRS-398 Quality Factors for Cs-137 Gamma Rays in Reference Dosimetry

Sang Koo Kang, Dong Joo Rhee, Yeong Rok Kang, Jeung Kee Kim, Dong Hyeok Jeong

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

Correspondence:Dong Hyeok Jeong(physics@dirams.re.kr) Tel:82-51-720-5813, Fax:82-51-720-5826

Received 29 May 2014       Revised 29 July 2014       Accepted 13 August 2014

Copyright © 2014 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

The Cs-137 irradiator is widely used to irradiate biological samples for radiobiological research. To obtain the accurate outcomes, correct measurements of the delivered absorbed dose to a sample is important. The IAEA protocols such as TRS-277 and TRS-398 were recommended for the Cs-137 reference dosimetry. However in TRS-398 protocol, currently known as the most practical dosimetry protocol, the quality factor () for Cs-137 gamma rays is not suggested. Therefore, the use of TRS-398 protocol is currently unavailable for the Cs-137 dosimetry directly. The calculation method previously introduced for high energy photon beams in radiotherapy was used for deriving the Cs-137 beam qualities () for the 15 commercially available farmer type ionization chambers in this study. In conclusion,  values were ranged from 0.998 to 1.002 for Cs-137 gamma rays. These results can be used as the reference and dosimeter calibrations for Cs-137 gamma rays in the future radiobiological researches.

Keywords: Cs-137 gamma rays, TRS-398 protocol, Quality factor

References

1. Brady SL, Toncheva G, Dewhirst MW, Yoshizumi TT. Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools. Health Phys. 7(3):195–205. 2009.
crossref
2. Sabine H. Methods in Radiobiology. Nanodosimetry Workshop (. 2009.
3. 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.
4. Moon YM, Kang YR, Kim JK, et al. Measurement of absorbed dose in mice using Glass Dosimeter implantation. Proceeding of KSMP spring meeting: 86–86 (. 2012.
5. Moon YM, Rhee DJ, Kim JK, at al: Reference Dosimetry and Calibration of Glass Dosimeters for Cs-137 Gamma-rays. Progress in Medical Physics. 24(3):140–143. 2013.
6. TRS-277: Absorbed Dose Determination in Photon and Electron Beams: An International Code of Practice. International Atomic Energy Agency, Vienna (. 1997.
7. 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.
8. Jeong DH, Shin KC, Oh YK, et al. Direct calculation of TRS-398 quality correction factors for high energy photons. Korean J Med Phys. 17(1):54–60. 2006.
9. Kang YR, Lee CY, Kim JH. Study on the Evaluation of TRS-398 Quality Factors with Central Electrode Corrections for Small Cylindrical Chambers. Korean J Med Phys. 22(3):148–154. 2011.
10. Andreo P, Nahum AE, Brahme A. Chamber-dependent wall correction factors in dosimetry. Phys Med Biol. 31:1189–1199. 1986.
crossref
11. Muir BR, Rogers DWO. The central electrode correction factor for high-Z electrodes in small ionization chambers, Med Phys. 38(2):1081–1088. 2011.
12. Andreo P. Improved calculations of stopping-power ratios and their correlation with the quality of therapeutic photon beams, Measurement Assurance in Dosimetry(Proc. Symp. Vienna, 1993), IAEA, Vienna: 335–359 (. 1994.

Fig. 1.
Quality factors including Cs-137 gamma rays determined in this study. The quality factor for Cs-137 is slightly higher than that of Co-60 gamma rays.
pmp-25-123f1.tif
Table 1.
Farmer type ionization chambers and its physical data used in this study.
Manufacturer Model Cavity volume (cm3) Cavity radius (cm) Wall material Wall thickness (g/cm2) Central electrode
Capintec PR06C/G Farmer 0.65 0.32 C-552 0.050 C-552
Exradin A12 Farmer 0.65 0.31 C-552 0.088 C-552
Nuclear Assoc. 30–751 Farmer 0.69 0.31 Delrin 0.056 Al
Nuclear Assoc. 30–752 Farmer 0.69 0.31 Graphite 0.072 Al
NE 2571 Farmer 0.6 0.32 Graphite 0.065 Al
NE 2581 Farmer 0.6 0.32 A-150 0.041 A-150
PTW 23333 Farmer 0.6 0.31 PMMA 0.053 Al
PTW 30001/30010 Farmer 0.6 0.31 PMMA 0.045 Al
PTW 30002/30011 Farmer 0.6 0.31 Graphite 0.079 Al
PTW 30004/30012 Farmer 0.6 0.31 Graphite 0.079 Al
PTW 30006/30013 Farmer 0.6 0.31 PMMA 0.057 Al
SNC 10073 Farmer 0.6 0.35 PMMA 0.060 Al
SNC 10074 Farmer 0.6 0.35 Graphite 0.085 Al
Sctronix-Wellhofer 69(FC65P) Farmer 0.67 0.31 Delrin 0.068 Al
Sctronix-Wellhofer 70(FC65G) Farmer 0.67 0.31 Graphite 0.068 Al
Table 2.
Individual physical quantities used for the calculation of quality factor for PTW-30012 ionization chamber for Cs-137 and Co-60 gamma rays. The expected quality factor extrapolated from the sigmoidal fit function with the TRS-398 data was slightly higher than the calculated value as shown in the table.
Physical quantity Cs-137 Co-60
sw,air 1.136 1.133
Pcav 1.000 1.000
Pdis 0.988 0.988
Pwall 1.002 1.001
Pcel 0.991 0.993
PQ 0.981 0.982
sw,airPQ 1.114 1.113
kQ,Q0 This study 1.002
  TRS-398 (Sigmoidal fit) 1.003
Table 3.
Quality factors for a Cs-137 gamma rays for 15 farmer type ionization chambers.
Manufacturer Model Cavity volume (cm3) KQ,Q (Cs-137)
Capintec PR06C/G Farmer 0.65 0.998
Exradin A12 Farmer 0.65 1.000
Nuclear Assoc. 30–751 Farmer 0.69 1.000
Nuclear Assoc. 30–752 Farmer 0.69 1.001
NE 2571 Farmer 0.6 1.001
NE 2581 Farmer 0.6 1.010
PTW 23333 Farmer 0.6 1.002
PTW 30001/30010 Farmer 0.6 1.002
PTW 30002/30011 Farmer 0.6 1.001
PTW 30004/30012 Farmer 0.6 1.001
PTW 30006/30013 Farmer 0.6 1.002
SNC 10073 Farmer 0.6 1.002
SNC 10074 Farmer 0.6 1.001
Sctronix-Wellhofer 69 (FC65P) Farmer 0.67 1.001
Sctronix-Wellhofer 70 (FC65G) Farmer 0.67 1.001
TOOLS
Similar articles