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29 August 2008

Answer to Question #4700 Submitted to "Ask the Experts"

Category: Medical and Dental Equipment/Shielding — Shielding

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

What is light lead made of? How can the weight be reduced without sacrificing radiation protection?

Possible products to replace lead in aprons include tin, tungsten, antimony, titanium, bismuth, and barium. Some products are used to reduce toxicity compared to lead; others are used to reduce the weight of the apron.

It may be possible that materials that are lighter in weight than lead can attenuate x rays to a similar extent due to properties of the material (mass attenuation coefficient) at certain x-ray energies. Be careful when comparing aprons that weigh less than lead that claim to have a similar lead-equivalent thickness (e.g., 0.5 mm lead). This value is typically quoted at a certain energy (e.g., 110 kVp), however, most of the x rays that strike the lead apron may be of much lower energy since they are scattered. It is very possible that at the lower energies, the lead equivalent of an apron made of different material is significantly lower and, therefore, may not provide the same amount of protection.

When choosing aprons made of something other than lead, ask the vendor for a plot of the lead-equivalent thickness of the apron that covers the useful range of diagnostic x-ray energies.

Ken "Duke" Lovins, MS, CHP

Answer posted on 24 August 2005. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of 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 specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.