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Original Article

Korean Journal of Medical Physics 2011; 22(2): 92-98

Published online June 25, 2011

Copyright © Korean Society of Medical Physics.

Evaluation of the Output Dose of a Linear Accelerator Photon Beams by Using the Ionization Chamber TM31010 Series through TG-51 Protocol to Postal Monitoring Output of RPC for 5 Years

TM31010 계열의 공동이온전리함과 TG-51을 이용한 선형가속기광자선의 5년간 출력선량 평가

Tae-Jin Choi*, Ok-Bae Kim

최태진*ㆍ김옥배

Departments of *Medical Engineering and Physics, Radiation Oncology, Keimyung University School of Medicine, Daegu, Korea

계명대학교 의과대학 *의공학교실, 방사선종양학교실

Abstract

This study is to keep the accuracy and stability of the output dose evaluations for linear accelerator photon beams by using the air ionization chambers (TM31010, 0.125 cc, PTW) through the Task Group 51 protocol. The absorbed dose to water calibration factor NdwCo-60 was delivered from the air kerma calibration factor Nk which was provided from manufacture through SSDL calibration for determination of output factor. The ionization chamber of TM31010 series was reviewed the calibration factor and other parameters for reduce the uncertainty within ±2% discrepancy and we found the supplied NdwCo-60 which was derived from Nk has shown a −2.8% uncertainty compare to that of PSDL. The authors provided the program to perform the output dosimetry with TG-51 protocol as it is composed same screen of TG-51 worksheets. The evaluated dose by determination of output factor delivered to postal TLD block for comparison the output dose to that of MDACC (RPC) in postal monitoring program. The results have shown the 1.001±0.013 for 6 MV and 0.997±0.012 discrepancy for 15 MV X rays for 5 years followed. This study shows the evaluated outputs for linear accelerate photon beams are very close to that of international output monitor with small discrepancy of ±1.3% with high reliability and showing the gradually stability after 2010.

KeywordsTG-51, Absorbed dose to water, NdwCo-60, Output factor, TLD monitor

Korean Society of Medical Physics

Vol.35 No.2
June 2024

pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829

Frequency: Quarterly

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