22NRM07 GuideRadPROS: A survey on calibration of radiation protection dosimeters in photon reference fields – current practices and standardization and training needs

Regular calibration of radiation protection dosimeters is of great importance to ensure accurate measurements and the adequate protection of workers and the public. Calibrations are required by the European Legislation (EURATOM directive) and by many individual countries, both in Europe and in other regions. Some countries have additional requirements, such as verification, testing or type testing of dosimeters. All these requirements improve the confidence in measurements and improve overall radiation protection. Photon dosimeters are typically calibrated and tested in reference radiation fields, which are realized in Primary and Secondary Standards Dosimetry Laboratories according to the standard ISO 4037. The standard was updated in 2019, but early adopters reported problems with its implementation and missing data. Especially smaller laboratories needed additional training. This was one of the main reasons to establish a project within European Partnership on Metrology, with the name 22NRM07 GuideRadPROS “Harmonisation, update and implementation of standards related to radiation protection dosimeters for photon radiation”. A survey was organized in the project, and 40 replies were received, with 34 answers from 27 European countries. Considering the small number of calibration laboratories and considering that some countries do not have any calibration laboratories, the coverage of Europe was excellent. The survey showed that only half of the respondents completely implemented the new version of ISO 4037. Setting up gamma reference fields is clear to most respondents, but around half of the respondents have problems (unclear requirements, missing information, difficult to implement) with X-ray reference fields, half-value layer measurements and measurement uncertainty. Only a few respondents stated that X-ray tube voltage, spectrometry and Am-241 fields are adequately covered in the standard. A significant number of laboratories expressed training needs in high voltage measurements (27 respondents), spectrometry (24), setting X-ray reference fields (18), measurement uncertainty (18) and other topics. Survey inputs are used by 22NRM07 GuideRadPROS project to develop training courses and e-training materials, and to collate future research needs. The project will generate guidelines on spectrometry and will investigate conversion coefficients and associated uncertainties allowing for a future edition of the ISO 4037 standard.