To Bioassay or not to Bioassay!!

[a.zapantis@qut.edu.au (Alex Zapantis)]

I am re-writing the Radiation Procedures Manual (which is actually more
policy than procedures) for my University and am attempting to set
guidelines on when a routine bioassay program is required. Rather than
sprouting vague "handwaiving" recommendations I would prefer to set
quantifiable limits which determine if routine bioassay is indicated. Also,
I would like these limits to be applicable to any practice using any
unsealed radioactive substance.

I would appreciate comment on what I have come up with (see below).


Routine bioassay is required if the sum of the total activity of all
radioisotopes in unsealed form measured as the number of Annual Limits on
Intake (most restrictive ALI for each isotope) manipulated by a radiation
worker within 12 months exceeds 30ALIs.


REASONING:

Assume that 1% of the activity of all unsealed radioisotope manipulations
are depositied in the worker and set the "monitoring level" at 30% of the
yearly effective dose limit.

To receive an effective dose of 30% of the limit 0.3ALIs must be
ingested/inhaled. Since 1% is ingested/inhaled, the number of ALIs required
to be handled is 30 (ie 0.3/0.01).




All opinions appreciated. Also, am I reinventing the wheel here? I suspect
that I might be.

Regards



                        Alex Zapantis
                        Radiation Safety Officer                               
                        Queensland University of Technology          
                        Health & Safety Section                             
                        Locked Bag No.2
                        Red Hill Qld 4059
                        AUSTRALIA

                        Ph     : 61 7 864 3566
                        fax     : 61 7 864 3993
                        email  : a.zapantis@qut.edu.au