Non-lead cap offers strong radiation defense for interventional cardiologists

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Interventional cardiologists performing fluoroscopy-guided procedures take some of the highest hits of ionizing radiation among all who practice medicine. A new study shows that the exposure tends to concentrate on the left and center cranium.

It also shows that a disposable, non-lead head cap on the market for several years can cut exposure to near-ambient levels.

Reporting in the August edition of the  Journal of the American College of Cardiology: Cardiovascular Interventions, Ryan Reeves, MD, of UC-San Diego, and colleagues describe how they evaluated seven cardiology fellows and four attending physicians, all prospectively enrolled, who performed diagnostic and interventional cardiovascular procedures guided by fluoroscopy.

They outfitted the invasive cardiologists in the group with a lightweight, nonlead cap lined with the radiation attenuator XPF (barium sulfate/bismuth oxide), fixing six dosimeters across the outside and inside of the cap (left, center, and right).

Three dosimeters were placed outside the catheterization lab to measure ambient exposure.

The researchers recorded far greater total radiation exposure at the outside left and outside center (106.1 ± 33.6 mrad and 83.1 ± 18.9 mrad, respectively) versus outside right (50.2 ± 16.2 mrad; p < 0.001 for both) locations of the cranium.

Meanwhile the cap attenuated exposure at all sites to a level slightly higher than that of the ambient control (38.3 ± 1.2 mrad, p = 0.046).

The authors point out that the major scatter source is usually to the left side of the operator because most cardiovascular-cath procedures are performed from the right side of the patient, regardless of access site, placing the left and center regions of the operator’s head closer to the radiation source.

In their report discussion, Reeves and colleagues note that previous investigations have evaluated lead-based caps and concluded that they work well but are heavy and uncomfortable enough to curb widespread adoption.  

The attenuating cap used in the current study “was well tolerated and significantly reduced cranial radiation exposure, especially in the region that received the highest level of radiation,” they write. “The left side of the head was protected to the greatest magnitude, resulting in exposure similar to that at the other two locations inside the cap and only marginally greater than ambient control dosimeters far removed from medical radiation.”

The cap is manufactured by Salt Lake City-based Bloxr Corp., which sponsored the study but did not participate in the writing of the protocol or the analysis of the data, according to the study’s authors.