Defective lead aprons give themselves up to infrared light

Radiology researchers at Children’s National Health System in Washington, D.C., have shown that infrared thermal testing is better than the human touch at finding wear spots and other defects in protective lead aprons.

Prospectively assessing the performance of radiology workers using both a tactile inspection and an infrared inspection of a lead apron phantom over a 2-month period, Sarah E. McKenney, PhD, and colleagues found half of 31 participant inspectors correctly identified all “planted” defects when using an infrared technique developed at the institution.

Using hands and eyes alone, only 9 percent of participants found all the defects.

The team describes their work in an article published online Nov. 8 in the Journal of the American College of Radiology.

For the phantom, the researchers planted nine holes of increasing diameter, from 2 to 35 millimeters.

Their experimental detection technique used a 250-watt incandescent heat lamp bulb and a smartphone-compatible infrared camera.

Using a weighted average, they found that 7.5 defects were detectable with the infrared method vs. 5.4 with the tactile.

Infrared light “can penetrate an apron’s protective outer fabric and illuminate defects below the current standard rejection size criteria,” McKenney and colleagues comment. “Infrared imaging is a compact and portable inspection method that effectively detects defects in radiation protective apparel such as lead aprons and gonadal shields, essential for ensuring patient and staff safety.”

They add that their work may challenge popular practices, as the infrared technique is not only demonstrably accurate but also readily available and potentially affordable even by radiology operations with tight budgetary constraints.

In a news item posted by Children’s National, senior study author Stanley Fricke, PhD, says it’s standard for health care institutions to use a tactile-visual approach to inspect radiation protective apparel. However, that increasingly common inspection method “can allow aprons with holes and tears to slip by undetected,” he says, “due to the large surface area that needs to be inspected, the outer fabric that encloses the protective apron and other factors.”

Earlier this year NYU Langone researchers found nearly two-thirds of protective lead shields had detectable lead dust on the surface, prompting the authors to urge all imaging departments and centers to switch to lead-free shielding materials.