[ RadSafe ] X-Ray On Lights

[Morgan, Ben]

David,

I see your point about interrupting an X-ray but here's what the Rhode
Island regulations have to say:


H.6.15 Additional Requirements. Treatment rooms which contain a
therapeutic radiation machine capable of operating above 150 kV shall
meet the following additional requirements:
(a) All protective barriers shall be fixed except for entrance doors or
beam interceptors.
(b) The control panel shall be located outside the treatment room.
(c) Interlocks shall be provided such that all entrance doors, including
doors to any interior booths, shall be closed before treatment can be
initiated or continued. If the radiation beam is interrupted by any door
opening, it shall not be possible to restore the machine to operation
without closing the door and reinitiating irradiation by manual action
at the control panel; and
(d) When any door referred to in H.6.15(c) is opened while the X-ray
tube is activated, the air kerma rate at a distance of 1 meter from the
source shall be reduced to less than 1 mGy (100 mrad) per hour.


H.7.17 Facility Design Requirements for Therapeutic Radiation Machines
Operating above 500 kV. In addition to shielding adequate to meet
requirements of H.9, the following design requirements are made:

(e) Room Entrances. Treatment room entrances 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" and when
it is "OFF".
(f) Entrance Interlocks. Interlocks shall be provided such that all
access controls are activated before treatment can be initiated or
continued. If the radiation beam is interrupted by any access control,
it shall not be possible to restore the machine to operation without
resetting the access control and reinitiating irradiation by manual
action at the control panel.

http://www.rules.state.ri.us/rules/released/pdf/DOH/DOH_3166.pdf


I think all of these state regulations are implementing the same Federal
guidance but it's interesting how many different ways they've found to
do it.

Virginia requires lights that tell you when the beam is "on".

Rhode Island requires lights that tell you when it's "on" and when it's
"off".

If you look at Maryland's regulations, they require a light when the
beam is "on" and the light has to be triggered by the physical detection
of radiation.

If you're interested in doing more comparisons the following is a useful
link:

http://www.crcpd.org/links.asp#State%20Radiation%20Protection%20Programs
%20(U.S.)

This is the Conference of Radiation Control Program Directors. Inc. site
that links to most of the state radiation protection programs.

Regards,

Ben

mailto:ben.morgan at pgnmail.com


-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of North, David
Sent: Friday, June 10, 2005 3:35 PM
To: radsafe at radlab.nl
Subject: RE: [ RadSafe ] X-Ray On Lights


As far as I know, the practice of mounting lights such as you describe
outside x-ray rooms is just that: a practice. But I am always willing to
be further educated. Another practice which nowadays is generally
discouraged is linking an exposure interrupter to the door. The idea is
to prevent someone from becoming inadvertently exposed if he/she opens
the door during a radiographic or fluoroscopic procedure. The problem is
that while you may prevent a tiny dose to the door-opener, you have
interfered with an x-ray exam and possibly necessitated additional (much
greater) dose to the poor patient.

I can't see why a DEXA scanner would ever need such a light because the
stray radiation levels from those units are so low that the tech can sit
in the room right next to the scanning couch all day and not even come
close to any reasonable ALARA limit.

An "X-RAY ON" light outside the SPECT/CT ROOM is a reasonable idea just
for the fact that there is a CT scanner in the room. The door shouldn't
be locked in case the patient tanks and a code team needs to get in
there quickly.

David L. North, Sc.M., DABR
Associate Physicist
Medical Physics
Main Bldg. Rm 317
Rhode Island Hospital
593 Eddy St.
Providence, RI 02903
(401)444-5961
fax: (401)444-4446
dnorth at lifespan.org