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29 August 2008

Answer to Question #6328 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 are the more common types of shielding used in radiation therapy for the patient and also the radiotherapist?

The most common types of radiation therapy shielding for protecting the operator are concrete, lead, steel, and lead glass or lead acrylic. Doors may contain steel, lead, and polyethylene.

In the past, patient shielding was composed of a combination of bismuth, lead, tin, and cadmium in the form of poured blocks, which are also conformed to the primary beam. This is now being replaced on newer linear accelerators with multileaf collimators, which are typically made of tungsten.

Ken "Duke" Lovins, CHP

References

Thomadsen B, ed. Radiotherapy safety. In: American Association of Physicists in Medicine Symposium Proceedings No. 4. American Institute of Physics: New York; 1984: 32-34, 64.

Eichholz GG, Shonka JJ, eds. Hospital health physics. In: Proceedings of the 1993 Health Physics Society summer school. Richland, Washington: Research Enterprises; 1993: 57-60.

National Council on Radiation Protection and Measurements. Structural shielding design and evaluation for megavoltage x- and gamma-ray radiotherapy facilities. Bethesda, MD: NCRP; NCRP Report No. 151:69-71; 2005.

Answer posted on 23 March 2007. 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.