A study of lead shields used during x-ray and fluoroscopy procedures at an academic medical center in New York City showed that nearly two-thirds of the shields had detectable lead dust on the surface. The finding has prompted the study authors to urge all imaging departments and centers to switch to lead-free shielding materials.
The study posted online Jan. 9 in the Journal of the American College of Radiology.
Kevin Burns, MD, of Montefiore Medical Center, Jamie Shoag, MD, of NYU Langone Medical Center’s department of pediatrics and colleagues conducted their study on 172 lead shields.
They tested each shield for external lead dust via a qualitative rapid on-site test and a lab-based quantitative dust wipe analysis, flame atomic absorption spectrometry (FAAS).
They used a chi-squared test to gauge the association of surface lead presence with age of shield, type of shield, lead sheet thickness, storage method and visual and radiographic appearance.
Some 63 percent of the shields had detectable surface lead by FAAS and 50 percent by the qualitative method.
Lead dust by FAAS ranged from undetectable to 998 micrograms per square foot.
The team found the quantitative detection of lead was significantly associated with three variables:
- Visual appearance of the shield. Fully 88 percent of shields that scored 3 on scale of 1 (best) to 3 (worst) had detectable dust lead.
- Type of shield. A greater proportion of the pediatric patient, full-body and thyroid shields were positive than vests and skirts.
- Use of a hanger for storage. 27 percent of shields on a hanger were positive versus 67 percent not on hangers.
Radiographic determination of shield intactness, thickness of interior lead sheets and age of shield were unrelated to presence of surface dust lead, according to the study report.
The authors acknowledge single-site sample with unknown generalizability among their study’s limitations.
Also, because this was the first study of its kind, the researchers lacked a standardized protocol for testing the shields.
“We chose an area in the right upper quadrant for the qualitative and the middle of the shield for the quantitative method, and these locations may not represent the lead dust content of the entire surface,” they explain. “[W]e did attempt to mitigate this limitation by performing a four-quadrant analysis on a subset of shields, which showed consistent results in all locations.”
The authors call for further research to assess the clinical impact of their findings.
Chronic low-level lead exposure, often asymptomatic, “is toxic to both adults and children,” they emphasize. “Monitoring blood lead levels could be used to assess internal contamination via transfer of lead into the body, and hand wipes could be used to determine if lead dust is transferred from aprons to the hands of physicians, nurses and technicians.”