It’s time for radiology departments to remove lead shields during X-ray examinations, say medical physicists at the University of Colorado Aurora School of Medicine. They explain why technological changes in X-ray equipment have negated the hypothesis that shielding improves patient safety and made decades-old federal regulations obsolete in the April 2019 issue of the American Journal of Roentgenology. .
“Discontinuing patient screening will represent a significant departure from the way radiology has been practiced for decades,” wrote Rebecca M. Marsh, PhD, medical physicist and associate professor of radiology, and Michael Silosky, assistant professor of radiology. . “Although change is difficult, it is up to radiology technologists, medical physicists and radiologists to finally come forward as reasonable voices on the matter.”
Patient protection was introduced into the United States Code of Federal Regulations in 1976 and the wording did not change for the next 42 years.1 At the time, the regulation was intended to protect against the hereditary risks of radiation exposure. However, according to the authors, no heritable effects have been observed in humans since then.
Since 1959, radiation dose exposure from x-ray examinations to the testes and ovaries has been reduced by 96% .2 The authors note that the amount of protection provided by the shield varies depending on whether the anatomy is outside or within the image field of view (FOV). Protection of anatomy outside the image field of view provides negligible protection because it cannot protect against internal dispersion generated within a patient.
More importantly, screens can interfere with the function of automatic exposure controls. If they obstruct the field of view of the image, the radiographic system can greatly increase the tube output to attempt to penetrate the shield, resulting in an increase in patient dose and marked degradation in image quality. It may be necessary to film or interpret a radiologist to make a diagnosis from a non-optimized image.
The authors recommend that patients be informed prior to their examination that no protection is provided for the patient because the evidence shows that protection can actually increase the risk of radiation while providing negligible or no benefit. Technologists must be trained to provide information that answers patient questions and / or concerns. They should have the authority to provide protection in cases where they believe patients would benefit psychologically. The authors also recommend that radiology facilities use posters and / or brochures to explain why shielding is no longer appropriate.
“All recent conversations about patient shielding are centered around patient safety,” Dr. Marsh told Applied Radiology. “After considering all the available evidence, we believe that discontinuing the use of patient shielding in diagnostic imaging is in the best interest of patients.”