KAJIAN ANALISIS KETIDAKPASTIAN TLD POSTAL IAEA/WHO SEBAGAI STANDAR PROGRAM AUDIT DOSIS

Abstract

The International Atomic Energy Agency (IAEA) and World Health Organization (WHO) operate the IAEA/WHO TLD postal dose audit programme using thermoluminescence dosimeter (TLDs) for Secondary Standard
Dosimetry Laboratory (SSDL) and user every year. As National Reference Laboratory in the field of radiation metrology, PTKMR – BATAN always participates in the postal dose audit programme on therapy level for 60Co
beam. On the postal dose audit programme, the uncertainties in the dose determination from TLD measurements have been evaluated by IAEA, which is comprises of uncertainties in the calibration coefficient of the TLD system
and uncertainties in factors correcting for dose response non linearity, fading of TL signal, energy response, and influence of TLD holder. The individual uncertainties then have been combined to estimate the total uncertaintiy in
the dose evaluated from TLD measurements. The combined relative standard uncertainty in the dose determined from TLD measurements has been estimated to be 1.2% for irradiation with 60Co gamma rays and 1.6% for
irradiation with high-energy X-rays. Results from irradiations by Bureau Internationale des Poids et Mesures (BIPM), Primary Standard Dosimetry Laboratory (PSDL), and SSDL compare favourably with the estimated
uncertainties, whereas TLD results of radiotherapy centres show higher standard deviations than those derived theoretically. This paper presented the result of TLD postal dose audit for 60Co beam owned by PTKMR-BATAN
in the year of 2006-2008.