Re: Badge for X-ray machine users?

[BCOLE@AFP76.HUMC.EDU]

	Ted de Castro (>) posted:

>>>I would like to know if you issue TLD badge to the X-ray machine users on
>>>campus. 

>YES

>>>Most of the X-ray machines we have are used for engineering research
>>>and the users are unlikely to receive a greater-than-10% exposure. 

>TRUE - but the FDA, BRH, DHW - or whatever they are this week ---- has a 
>position that although the above is true - historically the film badge has 
>been a FIRST indication of an occurance.

>Personnaly I would strongly suspect that this may NOT be as true for a TLD 
>badge!

>Since we have gone TLD I have looked into unbadging these people ...... but 
>its a politically touchy issue.

	<snip>

"historically the film badge has been a FIRST indication of an 
occurance[sic]."
I don't understand why it is strongly suspected that this may NOT be as
true for a TLD badge.  Indeed the energy over-response at low photon 
energies (e.g. 10-30 keV) for TLDs (LiF TLD 100) is very much smaller 
than that of conventional x-ray film in a film badge.  The 
TLD dose response is flat for a large range.  But I don't think
the TLD versus film energy sensitivity or integrated dose response 
is the issue here for an industrial x-ray machine.  Perhaps it is 
thought that TLDs wouldn't be as much an indication of a first 
occurrence because the cross sectional area normal to an x-ray beam 
subtended by a TLD chip is smaller than that of a film badge.  
Maybe I am missing the point.  Clarification would be appreciated.
Thanks.

Brian H. Cole
Health Physicist
Harbor-UCLA Medical Center	disclaimer: this msg. is hereby disclaimed.