Operational Quantities for External Radiation Exposure

Draft document: Operational Quantities for External Radiation Exposure
Submitted by Tom Grimbergen, NRG Individual Monitoring Service
Commenting on behalf of the organisation

I would just like to add a few general comments:
1) as a teacher in radiation protection training courses I welcome any thorough scientific evaluation of the current system of radiation protection quantities, pointing out what the shortcomings are. And of course, suggestions of alternatives which solve shortcomings are very welcome. An additional advantage of a possible new system of quantities would be if the system is more straightforward and thus more easy to explain. For example, the time spend nowadays to explain the difference between dose equivalent and equivalent dose could probalbly be well spend on more useful subjects.
2) like many colleagues already pointed out, the negative practical and financial impact of changing radiation protection dose quantities might be much larger than maybe intended. One of the reasons of course is the large number of dosemeters for monitoring individual workers in the field. The system of individual monitoring in radiation protection is quite unique compared to other fields of occupational safety, and gives valuable insight in the possible exposure situation of many workers working with sources of ionizing radiation (even with the shortcomings of the existing system of quantities). Therefore the radiation protection community should be very careful with interventions which might negatively influence the cost-effectiveness of the system.
3) as for the proposed changes to the radiation protection dose quantities, they might solve some of the issues inherent to the current system, but certainly not all. There are, and there always will be, significant deviations possible between the “true” effective dose and a reading of a single dosemeter worn on the body of a worker. In the proposed system a number of irradiation geometries are considered. However, in the case of partly shielded fields (e.g. the often used lead aprons in medical applications) the translation of dosemeter reading to effective dose will be very much different, depending on which parts of the body are shielded, and on the position of the dosemeter (in the shielded part of the field, or not). In other words, dosemeter readings will always have to be handled with some care, and in some situations corrections might have to be applied. If we know the ideal system is not reachable (quantities with which individual dosemeter readings perfectly reflect the effective dose, in every possible irradiation situation), we might as well accept the shortcomings of the current system.