Answer to Question #2736 Submitted to "Ask the Experts"

Category: Radiation Workers — Pregnant Workers

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

Q

I am a cardiologist. I will be working in a catheterization lab. I am planning for a pregnancy. I want to know whether I should stop working in the cath lab in the postovulatory period or after confirmation of pregnancy.

A

You certainly should be able to work in the catheterization lab. Most countries have limits on the annual amount of occupational radiation exposure you can receive and the amount the fetus can receive—in the United States it is 50 millisieverts (mSv) for you and 50 mSv for the fetus (mSv is a unit of effective radiation dose).

Are you wearing a radiation badge? If you are wearing only one radiation badge and you wear it at the collar outside the lead apron, we can estimate the "effective" amount of radiation your body is receiving under the apron. According to a National Council on Radiation Protection and Measurements (NCRP) Report, if you wear only one badge and wear it outside the apron at the collar, you can divide the exposure reading by 21 to determine your whole-body effective dose. So, if your badge reading is 50 mSv, your effective whole-body dose is approximately 2.38 mSv (50/21). If we want to be conservative and assume no shielding from abdominal tissue for the fetus, then we'd say if your badge reading was 50 mSv, the fetus received 2.38 mSv. Using this method, you could look at your historical badge readings and calculate the effective dose you receive on average.

To be more accurate when you do become pregnant, you should contact your organization's radiation safety office for a second badge that you could wear under your apron at waist level. If you are already wearing a second badge under the apron, those readings should be a good indicator of the dose the fetus might receive. That can be compared against the 5 mSv limit.

As you're probably aware, there are several ways to reduce your exposure: increase your distance from the area where the beam is entering the patient (this doesn't mean you have to back away from the table—move down the length of the table if possible or at least move away when you can), use shielding (a 0.5 millimeter [mm] lead apron attenuates at least 96–97% of the x rays; typical portable leaded Plexiglas barriers attenuate about 98% of the x rays), keep the image intensifier as close to the patient as possible (the farther away the image intensifier is from the patient the higher the dose you'll receive), or reduce the amount of fluoroscopy time. Those are a few things you can do to reduce your exposure and still accomplish the work you need to do.

Kelly Classic
Certified Medical Health Physicist

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.
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