Answer to Question #1155 Submitted to "Ask the Experts"

Q

I am an interventional cardiologist. If I were to become pregnant, could I continue to work in the catheterization lab? I would prefer to not announce my pregnancy until after the first month or two has passed.

A

You certainly should be able to continue working in the catheterization laboratory. Most states have limits on the annual amount of occupational radiation exposure you can receive and the amount the fetus can receive—5,000 mrem for you and 500 mrem for the fetus. 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 5,000 mrem, your effective whole-body dose is approximately 238 mrem (5,000/21). 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 5,000 mrem, the fetus received 238 mrem. 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 might want to contact your local 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 500 mrem 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 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