Advanced Physics for Brachytherapy 2018

Chapter 5: Calibration at the SSDL and Hospital Level 5.2. Maintenance of standards for photon sources and intravascular sources Well type chambers should be recalibrated regularly. SSDL recalibrations at 137 Cs quality can be made at a PSDL or the IAEA Dosimetry Laboratory. 5.3. Maintenance of standards for 192 Ir quality Upon calibrating well type chambers every 2 years with HDR 192 Ir sources, some chamber types have shown calibration factor constancy to within 0.5%, and chamber-to-chamber variation of the ratio of HDR 192 Ir source calibration to 137 Cs and 60 Co also within 0.5%. Thus, a practical solution for checking a well chamber HDR 192 Ir source calibration factor is for the physicist to monitor chamber response throughout its lifetime by bracketing the 192 Ir average energy of 397 keV with 137 Cs and 241 Am sources.