Answer to Question #6517 Submitted to "Ask the Experts"

Q

What is the proper procedure for testing lead aprons for in a hospital setting?

A

The following sample procedure is a slight modification to the procedure offered by Rene Michel and Michael Zorn in their article "Implementation of an X-ray Radiation Protective Equipment - Inspection Program" published in Operational Radiation Safety Vol 82, Feb. 2002, pp 551-553:

1. Uniquely identify the lead apron with an identification number as well as the date of the most recent inspection and the due date for the next inspection.
   
   
2. Physically examine all lead aprons for gross defects such as tears, perforations, and thinning creases.
   
   
3. Remove lead aprons that do not pass physical inspection from use.
   
   
4. Examine remaining lead aprons fluoroscopically using manual settings and low technique factors (e.g., 80 kVp). Do not use automatic brightness control, as this will drive the tube current and high voltage up, resulting in unnecessary radiation exposure to personnel and wear on the tube. Note that shielded areas will appear dark and defects, seams, and stitching will appear light.
   
   
5. Remove defective lead aprons from service immediately and dispose of the lead apron properly (see ATE Question #1827).
   
   
6. Inspect lead aprons at least annually and upon request by the user. Some facilities may opt to inspect more frequently based upon use (and abuse) of the aprons.

While this is not an issue at hospitals, fluoroscopic equipment might not be available at smaller clinics. It is possible to radiographically examine the lead apron.

You will also want to establish some criteria for rejecting the lead apron. Lambert and McKeon ("Inspection of lead aprons: Criteria for rejection," Operational Radiation Safety Volume 80, May 2001) suggested replacing lead aprons if a defect is greater than 15 square mm unless the defect is clearly not over a critical organ. Lead aprons with defects along the seam, in overlapped areas, or on the back of the lead apron would be subject to the less conservative 670 square mm rejection criteria. Thyroid shields with defects greater than 11 square mm should be replaced. The British Columbia Center for Disease Control used a somewhat different approach and recommends rejection criteria of an aggregate area of 10 square cm over the whole body, 0.2 square cm over the reproductive region, and 1 square cm over the neck region (download its paper here).

Finally you should check your state radiation control regulations for requirements. For example, the Commonwealth of Pennsylvania has no regulations addressing lead apron inspections, but the great state of Texas does:

"Protective devices, including aprons, gloves, and shields shall be checked annually for defects such as holes, cracks, and tears. These checks may be performed by the registrant by visual or tactile means, or x-ray imaging. If a defect is found, protective devices shall be replaced or removed from service until repaired. A record of this test shall be made and maintained by the registrant in accordance with subsection (s)(1) of this section for inspection by the agency."

Note that this regulation is satisfied by a physical inspection or x-ray imaging inspection of the lead apron. This is the difference between the Michel and Zorn's procedure and the one above. The Michel and Zorn procedure recommends only performing fluoroscopic examinations of aprons suspect as a result of the physical inspection. Considering the regulation above and being able to cite a peer-reviewed article as justification, their procedure is worthy of consideration. The advantage of the procedure offered above is that it uses radiation to look for failure to attenuate radiation, i.e., it is a direct measure of the effectiveness of the lead apron. Therefore, a fluoroscopic examination may uncover some defects overlooked in a physical inspection. However, the disadvantage is the additional time to perform the fluoroscopic procedures, additional radiation dose to the inspector, and the availability of fluoroscopic equipment in busy facilities.

Kent Lambert, CHP