Answer to Question #3588 Submitted to "Ask the Experts"

I would like to know what kind of materials should be used in an x-ray room, for example, doors, etc., in order to protect all the people working outside.

X-ray rooms are shielded as necessary to make sure that radiation doses to persons outside the room do not exceed state limits for radiation workers or members of the public, based on who has access to the areas next to the x-ray room. Typically, the rooms are shielded with sheets of lead. When lead is used, it usually is glued on the backside of the sheets of drywall that make the room walls (the lead sheets overlap to prevent gaps in the shielding). For doors, the lead is usually "sandwiched" on both sides by wood. In addition, small pieces of lead are placed behind outlet boxes and over screws that hold the drywall up. It is usually difficult to tell if a room is shielded just by looking at it. The best place to see it is along the door edges if the door contains a sheet of lead.

Lead is not the only choice for x-ray room shielding, but it is the most commonly used due to cost and minimal thickness to achieve the amount of shielding desired. Some facilities use concrete or cinder block. Mammography facilities usually only require two sheets of drywall, for example, not lead, due to the low penetration ability of the x rays.

Ken "Duke" Lovins, CHP

Editor’s note:  Two National Council on Radiation Protection and Measurements publications that provide information on shielding of x-ray facilities are listed below. 

1. National Council on Radiation Protection and Measurement (NCRP) Report No. 35 “Dental X-Ray Protection" (1970) displays a number of wall sections that employ other materials including brick, cinder block, and fiberglass and their concrete equivalence.

2. National Council on Radiation Protection and Measurement (NCRP) Report No. 49 “Structural Shielding Design and Evaluation for Medical Use of X Rays and Gamma Rays of Energies up to 10 MeV” (1976).