Use of Portable Radiation Monitoring Equipment

["David W. Lee" <lee_david_w@lanl.gov>]

GROUP:

	I wish to respectfully solicit the advice/expertise of RADSAFERS on the
following issue.  I pose this issue to RADSAFERS because I have been out of
the NRC and medical world for some time and am not current as to the
subtleties of some present radiation safety practices in that arena.  I
presently work in the DOE (industrial? -- certainly non-medical) world.

	Radiation safety for industrial x-ray devices in the DOE world is expected
to be provided in accordance with guidance contained in ANSI N43.3,
American National Standard for General Radiation Safety -- Installations
Using Non-Medical X-Ray and Sealed Gamma-Ray Source, Energies Up To 10 MeV,
January 1993.  In the case of what this standard calls "Shielded
Installations," the x-ray machine operator is required to carry a
calibrated portable radiation monitoring instrument, such as an Eberline
Model RO-2, into and out of the x-ray exposure room each and every time
he/she enters/exits the x-ray room.  The intent of using such a portable
x-ray detector is to provide the operator an additional means, apart from
the various kVp meters, mA meters already on the x-ray control panel, of
verifying that the x-ray beam truly of "off."

	I note that 10 CFR 35.600 in the NRC world requires Co-60 teletherapy
rooms to be equipped with a room area radiation monitor.  This part also
requires the radiation safety organization that has jurisdiction over such
a unit to have portable radiation detection survey instrumentation
sufficient to perform the various radiation surveys specified in 35.641.
But I note that 10 CFR 35.600 does NOT contain any explicit requirement for
the Co-60 machine operator to carry and use a portable radiation monitoring
instrument anytime he/she enters/exits the treatment room.

	Therefore, my question:  Is it correct in your judgment for me to conclude
that having an area radiation monitor inside the treatment room is
sufficient to exempt the Co-60 unit operator from having to carry and use a
portable radiation monitoring instrument upon entering/exit of the room to
verify that the radiation beam is "off"?

	I do not wish to seem to be splitting semantic hairs here.  In my
non-medical, DOE world, the question has now come up as to whether a
properly placed, calibrated area radiation monitor properly installed
inside the x-ray exposure room can/should be regarded as the serving the
same function as an operator carrying and using a portable radiation
monitoring instrument upon each entry/exit of the exposure room.

	This question may not be of wide interest to the general RADSAFE
community; therefore, I leave it to your judgment as to whether or not you
wish to post your response to the RADSAFE net or merely respond to me
individually.

Thank-you.

Best regards  David 
David W. Lee
Los Alamos National Laboratory
Radiation Protection Services Group (ESH-12)
PO Box 1663, MS K483
Los Alamos, NM  87545
PH:   (505) 667-8085
FAX:  (505) 667-9726
lee_david_w@lanl.gov