Source of Support: None, Conflict of Interest: None
The international Atomic Energy Agency (IAEA) has recently started a service to provide calibration of brachytherpy sources, traceable to the International Measurement S stem, through IAEWHO network of secondary standard dosimetry laboratories (SSDLs). Two types of 13'Cs sources, CDCSJ type tube and CDC-1100 type miniature cylinder, calibrated at the National Institute of Standards and Technology (NIST), USA
are used by the IAEA as reference standards for providing traceable calibration to SSDLs, using well-type ionization chamber. The work carried out at the IAEA to standardize the measurement and the procedure recommended to transfer the calibration from the IAEA to SSDLs and on to the users are documented in the IAEA-TECDOC-1079 published in 1999. The salient features of this document are explained in this paper.