Re: Radiation monitoring badges in cine/floro exams

["Sandy Perle" <sandyfl@ix.netcom.com>]

Chris Jeffrey stated:

>I'm never convinced about the arguments which suggest the position
should be such as to record the highest received doses. The dosemeter
should record an indication of the whole body dose and as such should
be worn at chest or waist height. In fluoroscopy examinations, when a
lead apron is worn, the dosemeter then should clearly be under the
lead. <

This statement is very accurate. While working in the power reactor 
world, the normal procedure had been to relocate the dosimeter to the 
highest area of exposure, which resulted in extremely conservative 
dose reporting and assignment of doses that generally were >50% of 
what the more accurate dose assessment should have been. The practice 
of multibadging relieved many of these excessive over-assessed dose 
assignments. The major problem I have encountered while assessing 
many nuclear facilities is that the computer programmers found it 
simpler to take the highest of all of the multibadging periods and 
"still" were reporting an excessive exposure. Ideally since each 
multibadged dosimeter is assigned to a specific body location, the 
proper methodology would be to have the computer system track each 
body location and at the end of the badging period, simply assign the 
location with the highest DDE, SDE that respective dose. 


>"If a person is wearing a protective apron then in addition to a
 dosemeter worn under the apron, one or 
more dosemeters should be worn on unprotected parts of the body if
there are likely to be contributions greater than 1/10 of the
effective dose equivalent from their exposure"  <

This is bascially what many of the power reactors do, but the 
methodology of how the resultant dose is determined, as discussed 
above, is very important.

>The regular dosemeter should always be worn under the apron where it
monitors dose to the trunk and so to organs with the larger weighting
factors. If dose rate in the environment is high, such as in the
region of the cath lab table additional dosemeters should be worn
outside the apron. The exact position of additional dosemeters , on
the collar, sleeve or nailed to the forehead is probably immaterial,
but should be standardised locally.<

For times when multibadging is not utilized, the system should use 
the single dosimeter and add that dose repsonse to the areas that are 
currently "not" being monitored. The issue to be contended with is 
that when only a single dosimeter is being worn under an apron, the 
other body locations that are not protected are still receiving 
exposure, and are not being accounted for. I believe that a minimum 
of at least one badge needs to be worn outside of the apron to 
account for the DDE and SDE .... which can then be used to assess 
other body locations that aren't always monitored by multibadging.


Sandy Perle
Director, Technical Operations
ICN Dosimetry Division
Office: (800) 548-5100 Ext. 2306 
Fax: (714) 668-3149

E-Mail: sandyfl@ix.netcom.com