|First of all, we would like to express our appreciation for the
possibility which has been offered to the community to comment on the
Our concern is mainly with Chapter 3 (Quantities used in radiological
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
1) whenever in vivo biological data are lacking
2) to define operational quantities
3) for internal irradiation
The dual system so defined presents several drawbacks:
1) 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.
2) 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.
3) 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 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.
W. R. Casey - Brookhaven National Laboratory
Donald Cossairt - Fermi National Laboratory
Alberto Fasso - Stanford Linear Accelerartor Center
Nolan Hertel - Georgia Institute of Technology
Sayed Rokni - Stanford Linear Accelerartor Center
Working Group - Accelerator Section, Health Physics Society