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RE: Rads/rems (formerly radiographer "overexposure")
Similarly, re. photographic emulsions (film), ICRU-47 (Sect 3.8.1, p. 13)
states that "Absorbed doses as high as several Gy can be measured; however,
the concept of dose equivalent is no longer applicable at such levels."
Is it not an acknowledged fact that the stochastic risk was de-facto
determined from radiological accidents (i.e., doses in the 10's and 100's of
rads from nuclear bomb survivor data)? If so, why does ICRU claim that the
applicability of the concept to high doses is dubious? Is there not a
contradiction here?
Grant
-----Original Message-----
From: Fischer, Karl (NIH/OD/ORS) [mailto:fischerk@ors.od.nih.gov]
Sent: Tuesday, July 29, 2003 11:16 AM
To: 'radsafe@list.vanderbilt.edu'
Subject: Rads/rems (formerly radiographer "overexposure")
Regarding the usage of rads/rems for high doses, Paul Frame posted an
informative response back in 1998 (courtesy of the RadSafe archives):
**********
ICRP 60 p114
"The quality factor is applicable only for stochastic effects in the dose
range up to tens of mGy."
ICRU 51 p6
"The quantity dose equivalent is defined for routine radiation-protection
applications. It should not be used in numerical assessment of high level
exposures, for example in radiation accidents."
NCRP 91 p 11
regarding the quality factor Q "it is applicable at low doses for the
biological effects of primary concern i.e. cancer induction and severe
genetic defects. Q is only to be used at low absorbed doses in the range
of the annual radiation protection limits and not for the high doses that
might occur in accident situations."
In other words, there is no clear answer.
Paul Frame
Professional Training Programs
ORISE
framep@orau.gov
**********
Karl Fischer
kwf@nih.gov
-----Original Message-----
From: NIXON, Grant (Kanata) [mailto:GNIXON@MDS.Nordion.com]
Sent: Tuesday, July 29, 2003 10:09 AM
To: radsafe@list.vanderbilt.edu
Subject: RE: radiographer "overexposure"
Dear Bill,
I'm not sure why you claim that mrem is an "invalid" unit for acute doses (I
would think that either rems or rads would be appropriate but nothing with
"milli").
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