The following are comments pertaining to designing and implementing a veterinary x-ray room and associated darkroom.  Please feel free to have your architect contact us for specific shielding comments regarding any specific plan.  Rduncan@leswilkins.com

X-RAY ROOM

It is desirable to provide a separate enclosed room for radiology. Provide a 70 amp minimum (100 amp preferred) 220 volt (200 - 277) VAC. single phase power supply for the x-ray.  Make sure the circuit comes from at least a 37.5 KVA distribution transformer which any new construction should have available.  For older installations the equipment can run off a smaller size transformer, such as a 25 KVA.  Anything smaller than 25 KVA should be replaced, or the Hi Frequency Innovet can be internally limited in output power to preclude problems.

VOLTAGE RANGE: 200-277 VAC

LINE CURRENT @240 VAC: 140 Amps momentary; 6Amps continuous

LINE VOLTAGE REGULATION: 5%

NOMINAL BTU’S PER HOUR: 1,000

DISTRIBUTION TRANSFORMER: 37.5 KVA

WIRE SIZE TO DISCONNECT:

ALL COPPER 0-50’ #2; 51’ – 100’ #00; 101’ – 200’ 250mcm

Terminate this subservice on either side of the x-ray table on the backwall within arms reach. Locate it 5’ above the floor to the bottom of the disconnect (or breaker) box. The disconnect may be fuses, breakers, or a motor disconnect (one arm bandit type) per the National Electric Code.

Please see the circuit is all copper wire and includes a #6 ground. We do not require a neutral wire. If the disconnect is surface mounted, please include an 1-1/4" romex type connector for us to access the box. If the disconnect is recessed, please provide us with a conduit, 1-1/4" dropped down to a 8 x 8 J box at floor level, or provide a piece of flex conduit and stub out 24" at floor level.

In general, the x-ray room should have a rheostat installed on the lighting to allow subdued lighting levels. A solid core entry door is probably OK, pending formal calculations and submittal of a shield plan to your State regulatory authorities if one is required by your State.

DARKROOM

The darkroom is usually small, so careful layout of plumbing and electrical needs are important. For electrical, we need a duplex outlet for the processor, 115 VAC, and a 20 amp non dedicated circuit is generally fine. The best location for the outlet is on a side wall near the corner, or on the backwall behind the processor. If you plan on putting in a small shelf or cabinet on the other side of the darkroom, another outlet should be provided there for using an ID printer. A solid sheetrock ceiling should be specified for the darkroom.

A safelight and white light circuit should be provided and independently switched. In addition, an exhaust fan should also be installed. Generally the fan and safelight are switched together at standard switch height, and the white light switch is installed 18" above the other two. Inexpensive porcelain sockets can be used for the safelight and an incandescent bulb. Be sure to use a quality safelight fixture such as a Kodak with a type GBX filter which will work for all rare earth films. Another alternative is to provide a switched socket for a fluorescent type safelight. These safelights have become very popular, are wall mount and can be controlled by a wall switch or they include a pull chain. Weather-strip the door too so it is light-tight. The door should be solid core. We recommend an off white color for darkroom paint as safe light is better reflected.

Local codes can vary and will always take precedence; however, the AFP Mini Med and Konica SRX-101 have built in air gaps on the water inlets and so a backflow prevention device may not be required on the cold water supply line from a practical point.   Some local codes however may still require a "backflow prevention device" in addition to an airgap.

A 1/2" supply line should be provided and located on the backwall or side wall, so as not to interfere with the processor or the opening of the processor lid. In that regard, it is better to have the water supply located on a side wall, as close the wall as possible. It should have a ball valve installed and a water filter, if you have sediment in your water or if you are on a well. It is a good idea to have your plumber install one anyway and change the cartridge annually. Most processors including the AFP Mini Med connect with a washing machine hose, so terminate the water supply in hose threads. In lieu of a ball valve, a hose bibb may be installed, but check local codes with your plumber.

The drain must be PVC and at least 1-1/2" diameter. We like to have the drain roughed in at about 9" above the floor, a P trap installed and a short standpipe inserted with a wye on top of the standpipe. Overall the height should be no more than 20 " above the floor, and the lower the better. We also have to install a silver trap cartridge and since they are gravity flow, we may have to shim it up off the floor. All in all it gets pretty tight around the processor, so please have the plumber keep all plumbing close to the walls. Do not scrimp and make your darkroom so small that it cannot accommodate the replenishment tanks and silver cartridges or E-Pan chambers that local codes may require.

 X-RAY ROOM SHIELDING

In general there is no specific requirement for shielding in each wall, but rather a requirement to limit primary and scatter radiation to acceptable levels. In general you do not need additional shielding on an outside wall. Usually an extra (3^rd) layer of sheetrock will be sufficient to provide additional protection to occupied areas around your x-ray room. If you plan on doing standing laterals with the primary beam pointed at a wall bordering an occupied area, that wall will require some lead shielding.

If your State requires a barrier for the operator to stand behind, then a Control booth wall shall be shielded with 2 lb lead to a height of 7’. Any wall considered a Primary wall will need a layer of 4 lb lead. Film stored in a neighboring darkroom may need lead protection, or a steel film bin as a minimum. IF IN DOUBT CONTACT A HEALTH PHYSICIST in your State for specific advice. If in the Northwest US, contact Roy Duncan at Les Wilkins & Assoc. regarding your specific situation.

Last Updated 05/23/08

Copyright 1999