[ RadSafe ] X-Ray On Lights

[james.g.barnes at att.net]

Peter;

Here are some that immediately came to mind; I don't know if they are applicable to your situation, but a manufacturer would have to comply to them.

[CITE: 21CFR1020.31] (Radiographic)
(j) Beam-on indicators. The x-ray control shall provide visual indication whenever x-rays are produced. In addition, a signal audible to the operator shall indicate that the exposure has terminated.

[CITE: 21CFR1020.32] (Fluoro; not exactly a light, but still an alarm requirement.  In this situation the concern may be that a warning light would interfere with the physician's "dark adapted" vision; this is speculation on my part)

(h) Fluoroscopic timer. Means shall be provided to preset the cumulative on-time of the fluoroscopic tube. The maximum cumulative time of the timing device shall not exceed 5 minutes without resetting. A signal audible to the fluoroscopist shall indicate the completion of any preset cumulative on-time. Such signal shall continue to sound while x-rays are produced until the timing device is reset. As an alternative to the requirements of this paragraph, radiation therapy simulation systems may be provided with a means to indicate the total cumulative exposure time during which x-rays were produced, and which is capable of being reset between x-ray examinations. 

[CITE: 21CFR1020.33] (CT Equipment)
(h) Beam-on and shutter status indicators. (1) Means shall be provided on the control and on or near the housing of the scanning mechanism to provide visual indication when and only when x rays are produced and, if applicable, whether the shutter is open or closed. If the x-ray production period is less than one-half second, the indication of x-ray production shall be actuated for one-half second. Indicators at or near the housing of the scanning mechanism shall be discernible from any point external to the patient opening where insertion of any part of the human body into the primary beam is possible.

The following are other references:

NCRP Report #33, Medical X-ray and Gamma-Ray Protecton for Energies Up To 10 MeV.

3.2, Fixed Radiographic Equipment; 3.2.1
(g):  The control panel shall include a device (usually a milliammeter) to give positive indication of the production of x rays whenever the x-ray tube is energized. [It appears the mA meter is being substituted for a light.-jgb]


3.4, X-ray Therapy Equipment; 3.4.1
(h):  An easily discernible indicator which shows whether or not x rays are being produced shall be on the control panel.

(r)  An easily discernible or audible indicator which shows whether or not x rays are being produced should be provided in the treatment room for x-ray equipment capable of operating above 500 kVp.


There are also THESE requirements for NON-medical systems.

[CITE: 21CFR1020.40]
(7) Additional controls and indicators for cabinet x-ray systems designed to admit humans. For cabinet x-ray systems designed to admit humans there shall also be provided: 
(i) A control within the cabinet for preventing and terminating x-ray generation, which cannot be reset, overridden or bypassed from the outside of the cabinet. 
(ii) No means by which x-ray generation can be initiated from within the cabinet. 
(iii) Audible and visible warning signals within the cabinet which are actuated for at least 10 seconds immediately prior to the first initiation of x-ray generation after closing any door designed to admit humans. Failure of any single component of the cabinet x-ray system shall not cause failure of both the audible and visible warning signals. 
(iv) A visible warning signal within the cabinet which remains actuated when and only when x-rays are being generated, unless the x-ray generation period is less than one-half second in which case the indicators shall be activated for one-half second. 
(v) Signs indicating the meaning of the warning signals provided pursuant to paragraphs (c)(7) (iii) and (iv) of this section and containing instructions for the use of the control provided pursuant to paragraph (c)(7)(i) of this section. These signs shall be legible, accessible to view, and illuminated when the main power control is in the “on” position. 

Hope this is useful.

Jim Barnes


-------------- Original message from "Vernig, Peter G." <Peter.Vernig at med.va.gov>: -------------- 


> 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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