CALIBRATION OF THE NPL SECONDARY STANDARD RADIONUCLIDE CALIBRATOR FORIR-192 BRACHYTHERAPY SOURCES

Safe and effective treatment with brachytherapy sources requires an ac curate knowledge of the local tissue absorbed dose rate derived from t he source reference air kerma rate. It is desirable that these air ker ma rate measurements be traceable to national standards. The NPL has e mbarked on a programme that will enable the user to assay brachytherap y sources in a convenient manner prior to treatment. Calibration figur es have been derived for the NPL secondary standard radionuclide calib rator for Ir-192 brachytherapy sources manufactured by Amersham Intern ational plc. The calibration figures enable the user to accurately est imate the reference air kerma rate and activity of such sources by mea suring the ionization chamber response. Calibration figures for other brachytherapy sources are also being derived.