Ionisation chambers or solid state detectors for general radiology are calibrated against a range of X-ray spectra as defined in IEC 61267:2005, Medical Diagnostic X-ray equipment – radiation conditions for use in the determination of characteristics. The air kerma rates used are all traceable to the UK primary standards facility at the National Physical Laboratory (NPL). X-ray spectra are available from 40 kV to 150 kV to measure the instrument's performance over a broad range of energies.

For detectors used to measure the input doserates to image intensifiers or automatic exposure controls an additional spectrum is provided. This measures the performance of the detector to an X-ray beam similar to one that emerges from an irradiated object, such as a patient.

Detectors used in CT applications are calibrated against higher energy CT X-ray beams.

The standard calibration also includes a linearity test across the air kerma rate working range of the detector, incorporating an important check at the minimum doserate measurable by the instrument (for some instruments this is carried out at air kerma rates down to 15 µGy/min or 0.25 µGy/sec).