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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.