[ RadSafe ] X-Ray On Lights

Fri Jun 10 22:17:08 CEST 2005

Peter,

At the Harris Nuclear Plant our security X-ray machines have a light
that comes on when the beam is energized. Since these machines are
licensed by the state of North Carolina [an agreement state] I suspected
there might be something in our state regulations. I found the
following:

NORTH CAROLINA REGULATIONS FOR PROTECTION AGAINST RADIATION 15A NCAC 11

.0803 EQUIPMENT REQUIREMENTS

(f) An easily visible warning light labeled with the words "X-RAY ON" or
words having a similar intent, shall be
located outside each entrance into the room containing an analytical
x-ray tube and shall be illuminated only when
the tube is energized; or in the case of a radioactive source, shall be
illuminated only when the shutter is open. On
equipment installed after the effective date of this Rule, warning
lights shall have fail-safe characteristics.

Its not clear where this comes from but I started poking around at the
EPA, FDA and NRC web sites and eventually wound up at Virginia's
radiation protection regulations where I found:

12VAC5-480-8500. Therapeutic x-ray systems of less than one MeV.

B. Facility Design Requirements for Systems Capable of Operating Above
50 kVp. In addition to shielding adequate to meet requirements of
Sections 5 and 7 of these regulations, the treatment room shall meet the
following design requirements: 

1. Warning Lights. Treatment rooms to which access is possible through
more than one entrance shall be provided with warning lights, in a
readily observable position near the outside of all access doors, which
will indicate when the useful beam is "on." 

http://leg1.state.va.us/cgi-bin/legp504.exe?000+reg+12VAC5-480-8500

12VAC5-480-8510. X-ray and electron therapy systems with energies of one
MeV and above.

B5. Room Entrances. Treatment room entrances shall be provided with
warning lights in readily observable positions near the outside of all
access doors to indicate when the useful beam is "on". 

http://leg1.state.va.us/cgi-bin/legp504.exe?000+reg+12VAC5-480-8510

I also checked the section on diagnostic X-rays [12VAC5-480-8460.
General requirements for all diagnostic x-ray systems] but I didn't see
anything about entrance signs.

http://leg1.state.va.us/cgi-bin/legp504.exe?000+reg+12VAC5-480-8460

At the NRC's site I ran across Reg Guide 8.18 which is for maintaining
doses at medical facilities ALARA. In section C 3.2.a(2) the use of a
"Beam On" light is discussed for therapy units that use NRC-licensed
sources.

http://www.nrc.gov/reading-rm/doc-collections/reg-guides/occupational-he
alth/active/8-18/08-018.pdf 

Regards,

Ben

ben.morgan at pgnmail.com

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Vernig, Peter G.
Sent: Friday, June 10, 2005 11:39 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] X-Ray On Lights

If I might interrupt the debate about the toxicity and morality of DU
and the educational backgrounds of the participants I have a real
question that somebody on Radsafe might just help me with.

All of our fixed x-ray rooms including the cath labs have lights that
say X-Ray on and light up either when the rotor of a radiographic unit
is spinning [for those of you not familiar with medical diagnostic
x-rays the anode rotates to dissipate heat generated when the electrons
strike the anode and usually the rotor spins in anticipation of the
actual burst of electrons.] or when fluoro units are producing x-rays.

It seems that most if not all of the other VAs have a variation on this.
Wording may differ, one facility the light just goes on during x-rays so
that unless you stare at it, you'd miss it for radiographic units.

My question is does anybody know the origin of this.  A reg, rule, or
standard or best practice?

The reason I ask is technology is expanding and we have a DEXA [dual
energy x-ray analyzer] for bone densitometry which produces say 10% of
less of the x-rays that a normal radiographic unit puts out and we are
getting a hybrid SPECT/CT unit.  The DEXA doesn't have such a light and
we are tentatively planning on putting a light on the SPECT/CT.  But if
there is a standard or recommendation or some such it would be nice to
know just what it says.  BTW SPECT = single photon emission computed
tomography, a type of gamma camera.

Please don't bother with a check state regs or probably an NCRP.  I have
looked at both, but if anybody knows I would be very grateful for the
information.

Sorry to interrupt the political debate.

Any opinions in this e-mail are solely those of the author, and are not
represented as those of the VA Eastern Colorado HCS, the Dept. of
Veterans Affairs, or the US Government.

Peter G. Vernig, Radiation Safety Officer, MS-115, VA Eastern Colorado
Health Care System, 1055 Clermont St. Denver, CO 80220,
peter.vernig at med.va.gov, Phone= 303.399.8020 x2447; Fax = 303.393.5026,
alternate fax, 303.393.5248

"...whatever is true, whatever is noble, whatever is lovely, whatever is
admirable, if anything is found to be excellent or praiseworthy, let
your mind dwell on these things."

Paul of Tarsus
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