Accelerator Section Working Group Comments on Proposed ICRP 92
Bob Casey
You may recall that the Accelerator Section Board of Directors voted to form a working group to review the proposed International Commission on Radiation Protection (ICRP) Publication 92 as it relates to working at particle accelerators. Bob Casey was appointed the chair of the working group composed of Alberto Fasso, Stanford Linear Accelerator Center (SLAC); Don Cossairt, Fermi National Accelerator Lab (FNAL); Nolan Hertel, Georgia Tech; and Sayed Rokni, SLAC. Thanks entirely to the hard work of Alberto Fasso, the following set of comments were generated and forwarded to the ICRP.
Comments on Proposed ICRP Publication 92 from Accelerator Section Working Group
"First of all, we would like to express our appreciation for the possibility which has been offered to the community to comment on the recommendation draft.
"Our concern is mainly with Chapter 3 (Quantities Used in Radiological Protection). Many choices made by the commission since 1990, and largely maintained in the present draft, appear to be dictated by an effort to define a quantity--effective dose--directly representative of biological radiation effects as measured in vivo, regardless of the physical radiation field present inside the body.
"However, the commission has followed a different approach in the following cases:
- whenever in vivo biological data are lacking
- to define operational quantities
- for internal irradiation
"The dual system so defined presents several drawbacks:
- Lack of consistency. Biological uncertainty does not justify ambiguous or contradictory definitions, and stability should not be invoked to avoid correcting past errors. On the contrary, the fact, often mentioned in the draft report, that biological effects are only poorly known, should allow a definition of protection quantities based on a fully coherent physical model.
- Lack of universality. a given type of radiation should not be treated in a way dependent on how or where it is generated (externally or internally), but on the radiation field (spectrum of secondaries, dose distribution) it creates inside the body.
- Lack of simplicity. The commission's effort to simplify the system by defining only a few values for the radiation and tissue-weighting factors, useful perhaps (although not entirely obvious) in the field of regulations and measurements, is voided by the complication that the two different approaches create in other fields, such as dose calculations and shielding design.
"It must be noted that at least in the case of high-energy accelerators the current approach to radiation protection is widely based on the use of fluence-to-dose conversion coefficients: present-day computers allow us to calculate the latter with any practical level of accuracy even if the coefficients are based on complex physical models. Thus, simplicity is welcome in the sense of having to deal with a single, coherent system, not necessarily as mathematical simplicity.
"Again, thank you for the opportunity to offer these comments. If you would like to discuss these comments further, please do not hesitate to contact us. The accelerator community within the United States and in fact, world wide, is very interested in the recommendations established by the ICRP and welcomes the opportunity to participate in this process."
