Answer to Question #2186 Submitted to "Ask the Experts"

Q

I have two questions concerning x rays: (1) What different types of personal radiation dose meters are there? and (2) What are the procedures on protective clothing, storage, cleaning, and safety checks?

A

Many types of personal dose meters or "dosimeters" may be used to monitor x-ray exposure. Some of these are film badges, thermoluminescent dosimeters, and newer proprietary dosimeters read by lasers. Assuming we are speaking of medical x rays, film is probably the best because the x-ray energies are best determined leading to an accurate dose estimation. Film also happens to be the least expensive and can be stored after reading to serve as a permanent record of the exposure. On the down side, film is more sensitive to environmental stresses such as heat and moisture, but this can be kept negligible with proper use and storage of the badges. Electronic dosimeters may be used in addition to these "passive" dosimeters to track dose in real time. These resemble pagers and may be set to alarm at a particular exposure level. These may not be accurate at the very low energies of scattered x rays though—examine the specifications carefully.

Regarding protective clothing, lead aprons are the primary tool in diagnostic radiology. They may be stored anywhere in a controlled (ambient room) climate. They may be stored inside the exam room unaffected by x-ray exposure. Cleaning is your preference, but care should be taken to hang the aprons loosely. Laying them down, folding them, or stretching them may result in premature "cracking" of the lead, leading to small leaks in the shielding. The current standard for safety checks is to check for leaks or cracks in the aprons by observing fluoroscopic images of the aprons. This should be performed annually or biannually by individuals trained in operation and safety of fluoroscopic units.

John D. Lowe, MS, CHP, DABMP
Radiation Safety Officer
VA North Texas HCS