University of Pennsylvania
Radiation Safety Office

Veterinary Energized Equipment
User's Guide

Outline

A. Radiographic Units
B. Fluoroscopic Units
C. Mobile Units
D. Dental Units
E. Therapeutic X-Ray Units

A. Personnel Shielding
B. Structural Shielding

A. Personnel Dosimeter Policy
B. Dosimeter Placement
C. Dose Reports
D. Pick-up and Drop-off of Dosimeters

A. Registration of Energized Units
B. Acquisition of New Energized Units
C. Disposal of Energized Units

A. Proper Operating Procedures for Radiographic Units

1. Limit the X-ray primary beam limited to the smallest area possible consistent with the objectives of the clinical examination.

2. Align the X-ray beam properly with the animal and the image receptor.

3. Remain behind a protective barrier (i.e., a leaded glass wall, a leaded door, etc.) during the entire radiographic exposure.

4. Whenever possible, use restraining, supporting, or positioning devices for the animal, or use film for radiation exposures [PA 223.13.d].

5. State of Pennsylvania Rules and Regulations # 223.13.e:

"No Individual may be regularly employed to hold or support animals or hold film or hold the x-ray tube head during radiation exposures. Occupationally exposed individuals may not perform this service except in cases in which no other method is available. An individual holding or supporting an animal or film during radiation exposure shall wear protective gloves and apron having a lead equivalent of not less than 0.5 millimeter and shall be positioned so that no part of that individual's body will be struck by the useful beam. The exposure of an occupationally exposed individual used for this purpose shall be monitored."

6. Provide protective garments (lead aprons/shielding) for everyone whose presence is necessary during the radiographic exposure.

B. Proper Operating Procedures for Fluoroscopic Units

1. Only persons required for a fluoroscopic procedure should be in the room during the procedure.

2. As in a radiographic procedure, use the smallest possible beam area, thereby reducing the scatter radiation to personnel.

3. Fluoroscopic doses can also be minimized by reduction in the fluoroscopic time used. Perform quarterly outputs for Entrance Skin Exposure (ESE) rates for all fluoroscopes. Post the ESE Rates in the fluoroscopy room for reference by the physician/radiologist.

4. Use the timing device to indicate a preset time to serve as a reminder to keep it as short as possible. According to state regulations, the predetermined time should not exceed 5 minutes (PA 221.38).

5. Use the shortest possible distance from the image intensifier to the animal. For fluoroscopes equipped with AEC, AEC operations provide for automatic compensation, so that when longer distances are used, a higher radiation dose is given .

6. Thyroid shield, leaded gloves, and glasses should be available to the fluoroscopist to reduce exposure to thyroid, the extremities and eyes.

C. Proper Operating Procedures for Mobile Energized Units

If proper care is not taken, mobile equipment has a greater potential than standard equipment for unnecessary radiation exposure of personnel. In mobile units, variations can occur in exposures due to line voltage fluctuations, which can affect the output of the machine. Rechargeable units are capacitor discharge units are not affected.

a. Stand well away from the useful beam and the animal during the radiographic exposures. Distance is often the best possible protection from radiation.

b. Individuals, other than those whose presence is necessary to conduct the x-ray procedures, must be outside the x-ray room or, for field procedures, shall stand at least 5 meters away from the x-ray tube and from the animal.

c. Operators should wear protective garments with lead equivalent of at least 0.5 millimeter.

D. Proper Operating Procedures for Dental Units

1. Only persons required for radiographic procedure should be in the radiographic room during exposure. Everyone in the room must be adequately protected by protective garments.

2. Align the x-ray beam and film very carefully with the area to be radiographed.

3. Stand behind a protective barrier and observe the animal during the dental exposure.

4. The operator or the assistant must not hold the film in place during the exposure. Film holder devices must be used to hold the film in the place.

E. Proper Operating Procedures for Therapeutic X-Ray Units

1. Secure therapeutic x-ray units to prevent unauthorized use whenever the system is unattended.

2. Use mechanical supporting or restraining devices to hold the animal in position for radiation therapy .

3. The tube housing assembly must not be held during exposures.

4. No one may be in treatment room during irradiation unless protected by a shielded both.

5. Check interlocks, on-off beam control mechanisms, safety, and warning devices and at least once in a calendar year and service them appropriately.

Radiation exposure levels can be controlled via four basic methods:

1. Maximization of distance from radiation source.

2. Minimization of radiation exposure time.

3. Proper shielding of radiation source.

4. Proper shielding for personnel.

A. Personnel Shielding:

For personnel who remain in the room during examinations, it is important that they be protected by proper shielding, such as the following:

a. A leaded apron must be worn any time personnel are in a room during an exposure.

b. Thyroid shields: anyone likely to be exposed to high levels of scattered radiation to the thyroid during any procedure should wear this shield.

c. Leaded glasses: in fluoroscopy, the lens of the eye can often be exposed to high levels of scattered radiation.
The use of leaded glasses can greatly reduce this exposure.

d. Leaded gloves: anyone who must have his/her hand near the primary beam (as in the case where no
other means is available to immobilize an animal ) should wear leaded gloves to reduce exposure to the extremities.

B. Structural Shielding:

Each radiographic room has been designed with sufficient shielding in the walls to provide
protection to anyone on the outside of the room. It is important that the integrity of the
shielded walls not be tampered with. Therefore, if any personnel notice structural changes,
such as holes drilled into walls, Radiation Safety should be notified as soon as possible.

An employee should contact the Radiation Safety Office either directly or through the supervisor when she knows or suspects that she is pregnant. If for personal reasons an employee does not wish to disclose pregnancy to her supervisor, confidential disclosures can be made directly to the Radiation Safety Office.

A. Personnel Dosimeter Policy

Personnel monitoring is the method used by the Radiation Safety Office (RSO) to identify inadequate or improper radiation safety practices and potentially serious radiation exposure situations. The RSO will issue proper personnel dosimeters when evaluation of equipment reveals the radiation dose to personnel could potentially be larger than ALARA limits per calendar quarter to the whole body, (125 mrem).

Radiation workers are monitored by the University of Pennsylvania Radiation Safety Office. All radiation workers must conscientiously wear the radiation monitoring devices provided by the RSO. These devices may include the following:

a. A Film Badge to monitor doses to the whole body

b. A Ring Dosimeter to monitor extremity doses

c. A TLD badge for whole body measurements.

B. Dosimeter Placement

1. Interpretation of the measured dose is dependent upon the placement of the dosimeter. It is therefore important that all personnel wear their dosimeters correctly. The following list indicates where the dosimeters are to be worn:

a. Film Badge with no TLD Badge: wear the film badge above any protective clothing at collar level.

b. Film Badge with a TLD Badge: wear the film badge under the lead apron and the TLD above the apron at collar level.

c. Ring Dosimeter: wear ring dosimeters so that the employee's name is facing outwards.

2. Do not expose personnel monitoring devices to extreme heat or humidity. They are screened monthly. If any dosimeter has received a dose higher than the values shown below, the employee will be notified and the reason for the high reading will be investigated. Measures will be taken to keep radiation doses below these limits whenever possible.

Whole Body: 125 mrem/calendar quarter

Extremities: 1875 mrem/calendar quarter

It is very important that all personnel promptly return all monitoring devices every month.

C. Dose Reports

The Radiation Safety Office sends dose summary reports on a monthly and an annual basis . These reports should be posted in a conspicuous location in the department.

D. Pick-up and drop off of dosimeters

The Radiation Safety Office delivers new dosimeters to the veterinary school on the last Wednesday of each month. The Veterinary School must deliver the badges for New Bolton Center on the following day. The old dosimeters must be returned to the veterinary school designated personnel by the following Monday. The Radiation Safety Office will pick these by the following Wednesday for analysis.

Radiation survey of equipment checks the radiation safety characteristics of the machine comply with FDA and PA state regulations.

All safety problems observed by personnel, including conspicuous problems with energized equipment or with shielded rooms should be reported immediately to the Radiation Safety Office.

A. Registration of Diagnostic Units

According to Section 216.2 of 25 PA Code, Chapter 216, all radiation producing equipment must be registered with the Department of Environmental Resources. This registration is performed by the RSO on an annual basis. The RSO maintains a listing of all units currently registered.

B. Acquisition of New Diagnostic Units

It is the responsibility of clinical personnel to notify the RSO upon acquisition of any new diagnostic equipment. A radiation safety survey is conducted by authorized RSO personnel on all new units prior to their use.

C. Disposal of Diagnostic Units

It is the responsibility of clinical personnel to notify the RSO of any diagnostic equipment intended for disposal. The RSO will work in cooperation with the Environmental Health & Safety Office to ensure safe disposal of diagnostic units.

Radiation Safety Office, University of Pennsylvania: 898-7187