Answer to Question #5177 Submitted to "Ask the Experts"

Q

I am a dental hygienist looking for personal lead shielding. Most of the time I can be approximately four to five feet away (in the hallway) from the x-ray machine. Our dentist likes only D speed film. The usual setting is 70 kVp but ranges from 60 to 90 kVp. I take two to four films for established patients one time per year plus emergencies, and 18 films on all new patients over age 17 and again on all adults after three to five years. I have approximately 600 active patients total and x ray all of them one time a year and I see approximately 10 emergency patients and 10 new adult patients a month. Our walls are not lead lined. Sometimes I can not leave the room to take bitewing or periapical x rays due to patient incompliance, that is, age, mental capacity, severe gagging (this happens about two patients a month).

These instances have me next to the patient at a 45-degree angle to the cone, either holding the film or touching the patient's cheek/jaw to prevent movement. I am concerned with cumulative radiation over the course of my career and at 25 years old my husband and I are ready to start our family. Since most of my job is done while sitting (not x rays), would a vest/skirt combo be easier for all-day wear? Would a vest and gonad shield belt suffice? Is there a front apron flexible enough for repeat sitting/standing without quickly cracking? I want to wear my shielding under my smock.

A

Let's slow down a minute. Have you ever worn a dosimeter that
measures your radiation dose or do you know, from some other
measurement device, what your radiation dose is?




If you do, that would be good information for me to have. If not, some
national consensus reports contain radiation exposures for dental staff
(NCRP, UNSCEAR 2000). These reports show the measured annual radiation
doses for dental staff declining from 70 mrem per year in 1980 to 20 mrem per year in
1999 (mrem is a unit of effective radiation dose). For comparison, the
annual radiation dose limit for radiation workers is 5,000 mrem, the
limit for a pregnant worker is 500 mrem, and we all receive radiation
exposure from natural background radiation that totals approximately
300 mrem per year.




With that said, I do think you should wear a lead apron when you are
holding a patient or holding film in a patient's mouth. But to
continually wear lead all day when the radiation exposure you receive
is minimal (or zero) leads to other physical ailments such as lower
back and cervical problems. Our radiologists can attest to the fact
that no one should wear lead all day. These aprons are heavy—whether two
piece or not.




The final decision is certainly yours and you can obtain lead aprons
from several manufacturers. The aprons are all made pretty much the
same with several very thin layers of lead. If folded often, they will
crack or even get a small hole in them. They should be hung when not
being worn to minimize wear. For your comfort, I would suspect that a
two-piece would be better if worn while you are sitting quite a bit
with it on.




Kelly Classic


Certified Medical Health Physicist




References

National Council on Radiation Protection and Measurements. Exposure of the US population from occupational radiation. Report 101.




United Nations Scientific Committee on the Effects of Atomic Radiation.
Sources and effects of ionizing radiation. United Nations Publications:
ISBN 92-1-142238-8; 2000.