Overview
IEC TR 61948-4:2019 - "Nuclear medicine instrumentation - Routine tests - Part 4: Radionuclide calibrators" provides guidance for routine quality checks of radionuclide calibrators used in nuclear medicine. The report focuses on devices that use well-type ionisation chambers with a direct readout in units of activity. This second edition (2019) cancels the 2006 edition and includes a significant update to the system linearity test method to reflect technological developments in modern calibrators.
Key topics and requirements
- Scope: Routine tests (periodic QA) for radionuclide calibrators - complementary to acceptance testing methods described in IEC 61303 and device calibration practices in IEC 61145.
- Primary routine tests covered:
- Background response: measure and report instrument reading without a radioactive source (sample holder in place), using the most often-used nuclide setting.
- Constancy of instrument response: verify stability by measuring an ionisation chamber test source and comparing results to established reference data from acceptance testing.
- System linearity: updated test method (decaying-source approach) to evaluate the relationship between observed and predicted activity across the facility’s activity range. Test coverage stated includes the practical range from about 10 MBq up to 120% of the maximum patient-injected activity and at least up to 1 000 MBq; at least one data point per decade (recommended two in decaying source method) is taken. Data analysis uses decay-corrected, mono-exponential fits.
- Additional checks and frequency: the report lists other routine checks and recommended intervals (see Table 1 in the document for frequencies).
- Traceability: use of certified or traceable radioactive standard sources is emphasized for reliable reference and long-term constancy checks.
Practical applications and users
IEC TR 61948-4:2019 is intended for professionals responsible for radionuclide calibrator performance and patient safety:
- Medical physicists and nuclear medicine technologists performing routine QA
- Clinical engineers and service/maintenance personnel
- Calibration laboratories and quality management teams ensuring traceability
- Regulatory bodies and auditors reviewing compliance with routine testing protocols
Practical benefits include ensuring accurate activity measurement for patient dosing, maintaining calibration stability, documenting performance trends, and supporting compliance with local quality and safety regulations.
Related standards
- IEC 61303 - Radionuclide calibrators - particular methods for describing performance (acceptance tests)
- IEC 61145 - Calibration and usage of ionization chamber systems
- IEC TR 61948-1 - Routine tests - Part 1: Radiation counting systems
- IEC TR 60788 - Glossary of defined terms
Keywords: IEC TR 61948-4:2019, radionuclide calibrators, routine tests, nuclear medicine instrumentation, system linearity, ionisation chamber, decaying source method, constancy testing, background response, QA/QC.