Answer to Question #9288 Submitted to "Ask the Experts"

Category: Medical and Dental Equipment/Shielding — Shielding

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

If someone is in an x-ray room taking x rays and I am in an adjacent x-ray room taking x rays of a patient, does radiation go through the wall if the tube head in the other x-ray room is facing directly at me?

"The purpose of radiation shielding is to limit radiation exposures to employees and members of the public to an acceptable level" as stated in Structural Shielding Design for Medical X-Ray Imaging Facilities. Note that it is not designed to stop 100 percent of all x rays, as that is not possible from a physics standpoint (each additional increment of shielding reduces that amount that gets through exponentially, meaning that theoretically the amount getting through never reaches zero). This applies to primary, scatter, and leakage radiation.

The "acceptable level" of radiation doses are the limits prescribed by your state radiation control program. Typically, rooms are shielded so that occupational radiation workers will not exceed 50 millisievert/year deep dose in controlled areas, while members of the general public will not exceed 1 millisievert/year deep dose in unrestricted areas.

As a radiation worker in one of the x-ray rooms, you should have received radiation safety training from your facility and you should have a radiation dosimeter issued to you. As long as your dosimeter readings are at acceptable levels, you are assured that the shielding in the adjacent room (and all other x-ray rooms in your department) meet the design requirements based on your workload and location.

National Council on Radiation Protection and Measurements. Structural shielding design for medical x-ray imaging facilities. Bethesda, MD: National Council on Radiation Protection and Measurements; NCRP Report No. 147 (p 1); 2004. Available at:

Kennith "Duke" Lovins, CHP

Answer posted on 27 September 2010. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, 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. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.