Stability Checks of Secondary Standards Used for Calibrations in Diagnostic Radiology

Safe use of radiation sources requires use of appropriate radiation detectors and dosemeters. Dosimetry equipment needs to be calibrated in order to obtain accurate radiation dose measurements. Calibrations are performed in standards laboratories, which use primary, secondary or reference standards traceable to International System of Units [1, 2]. Secondary standards used for calibrations must be stable between two calibrations, and the stability checks are performed within this period. Requirements for reference class dosemeters, as set by IAEA TRS 457, are for the stability of chamber response to be within ±0.5 %, and for secondary standards to be within ±0.3 %. Monitor chambers can be used as reference instruments if they fulfill the same requirements that are set for the reference chambers.