In large part, the current System of Radiological Protection for humans is based on population averaged approaches for practical and ethical reasons, for example in the age- and sex-averaged values of Effective dose. There are nonetheless some areas where stratification is applied; detriment for example is calculated for the entire population and for a working age population in ICRP Publication 103, also an additional restriction to occupational dose limits is applied to pregnant workers. ICRP Publication 147 sets out an approach whereby Effective dose can be considered as an approximate indicator of possible risk, recognizing the lifetime risks vary with age at exposure, sex, and population groups (for example, Western European, Asian, North American etc). Principally, within the medical imaging community there is an increasing interest in having better indicators of risk from procedures for the individual patient. Furthermore, recent developments in dosimetry, particularly in the libraries of phantoms that encompass age, sex, height, weight and posture make it more feasible to provide more precise organ/tissue-specific doses accounting for these factors. Regarding cancer risk, a review of the method of calculation of the radiation-related detriment has been recently performed. As a result, a revision of the method has been launched, and proposes to include an update of cancer risk models and reference rates, better consideration of variations with region, sex and age, and improvement of severity weighting and interpretability.
Given the above background considerations and the evolving work being conducted within Task Group 111 on Factors Governing the Individual Response of Humans to Ionising Radiation, it is timely to consider whether and for which situations the system of protection should adopt a more individualised/stratified approach, particularly when considering low dose, low dose-rate and chronic exposures. Therefore, this Task Group is mandated to:
As a first step, the Task Group will review and identify the areas where elements of individualisation/stratification are employed within the system of protection, largely from ICRP Publications 103 and 147. The second step is expected to be an open topical meeting organised in cooperation with several organisations in formal relations with ICRP and others, with a particular focus on the medical sector. This dedicated meeting will serve to further identify current areas of individualisation/stratification and consider where individualisation/stratification may lead to better protection from the harms of radiation exposure.
The Task Group will hold regular meetings, largely by web-conference to deliberate on the relevant issues and draft a report to the MC suitable for publication in the Annals of ICRP. To allow full discussion of the issues, two face-to-face meetings are anticipated. The Task Group will keep abreast of developments of the work of other relevant ICRP Task Groups.
The Task Group will develop a report for publication in Annals of the ICRP that defines where the system of protection currently includes elements of individualisation/stratification and considers where further such individualisation/stratification could lead to better protection from the harms of radiation exposure. The Task Group is also encouraged to publish on progress as it develops through open literature publications.
A workshop will also be organised and hosted to facilitate wider radiation protection community involvement in the identification of relevant issues and topics for consideration; this is anticipated to be held online at an early stage of the TGs work.
In addition, the Task Group will develop materials suitable for ICRPædia in collaboration with the Scientific Secretariat.
|Simon Bouffler (Chair), UK Health Security Agency, United Kingdom|