AIR KERMA STANDARD AND MEASUREMENT COMPARISON ON SOURCE STRENGTH DETERMINATION FOR HIGH-DOSE RATE 192Ir BRACHYTHERAPY IN TAIWAN

This paper describes the establishment by the Institute of Nuclear Energy Research (INER, Taiwan) of the reference air kerma rate (RAKR) calibration standard for measurement of high-dose rate (HDR) Ir-192 brachytherapy source strength. A bilateral comparison has been made in the RAKR standards for HDR Ir-192 brachytherapy sources at the INER and Physikalisch-Technische Bundesanstalt (PTB, Germany) and the measurement difference was within the overall standard uncertainty and showed good agreement between the two calibration standard systems established at the INER and the PTB. Besides, INER also worked with 20 domestic hospitals to organise an on-site measurement comparison programme to explore the status of HDR Ir-192 brachytherapy source strength determination in Taiwan. The comparison results presented the ratios of RAKR with vendor values, as determined by INER and hospitals from the programme. The ratios fall in all cases within the +/-3 % guaranteed by the vendors for a coverage factor of k=2 or at 95 % confidence level.