Answer to Question #13777 Submitted to "Ask the Experts"

Category: Medical and Dental Equipment and Shielding — Lead Aprons

The following question was answered by an expert in the appropriate field:

Q

Our wildlife rehabilitation clinic occasionally uses a portable x-ray machine. We have gowns and gloves to wear, but restraining animals while taking radiographs requires me to be within a foot or so of the x-ray beam. My head and arms are not shielded. How dangerous is this to me, and what additional personal protective equipment (PPE) should I use?

A

If the gown and gloves you mention are leaded, then you are already following the first guideline/requirement that is appropriate for veterinary x-ray work, when your hands are in or near the primary x-ray beam. In typical x-ray use (veterinary or human), the head and arms are not shielded because there are no critical organs in the arms and the only critical organ in the head is the lens of the eye (but the eye lens typically has radiation dose limits that are three times higher than the limit for whole body, due to relative radiosensitivity differences). The thyroid is also in the vicinity and it is a good idea to use a lead thyroid collar if there is not one built in to your lead apron.

The next most important item of personal protection is a radiation dosimeter (also called a film badge). If you don't wear one already, it's a good idea in veterinary practice to wear one. The dosimeter should be worn at the collar level, outside any lead. This will give you results for whole-body dose, lens-of-eye dose, and shallow-skin dose (each of which typically has its own unique annual radiation dose limit) and will allow you to compare how much dose you receive vs. how much you are allowed to receive. Typically, workers in veterinary settings get less than 10% of the annual dose limit and are almost all below 30% of the annual limit.

Based on your comments about your current practice, it sounds like you are doing things safely, and in a manner consistent with other persons in your profession, however, it would be best if you review your practice with a qualified health or medical physicist. Normally, the state you are in will maintain a list of qualified experts who you can contact to help you with any radiation safety issues or questions that you may have.

Kennith "Duke" Lovins, CHP

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 23 December 2020. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.