Radiation Protection Critical for Vascular Surgeons

By Kerri Wachter

NEW YORK -- Any interventional fluoroscopic procedure poses health risks to vascular surgeons and those risks accumulate over the course of a career, said Dr. Gary Ansel at the Veith symposium on vascular medicine sponsored by the Cleveland Clinic.

It has long been thought by experts that there was a threshold of exposure, below which there was no harm associated with ionizing radiation.

However, the most recent report of the National Academy of Sciences' Committee on the Biological Effects of Ionizing Radiation supported a "linear, no-threshold model"--meaning that even the smallest dose of low-level ionizing radiation has the potential to increase human health risks slightly ("Health Risks From Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2" [Washington: National Academies Press, 2006]).

"So this minimum threshold of safety is a farce. There is no minimum level of safety for radiation," said Dr. Ansel, director of peripheral vascular intervention at Riverside Methodist Hospital in Columbus, Ohio.

The study committee defined low doses as 0-100 millisieverts (mSv) (sieverts measure radiation deposited in living tissue).

"If you get 100 mSv, your risk of having cancer is 1 in 100," said Dr. Ansel.

"SO THIS MINIMUM THRESHOLD OF SAFETY IS A FARCE. THERE IS NO MINIMUM LEVEL OF SAFETY FOR RADIATION."

What does that mean in terms of vascular surgery procedures? Ten minutes of fluoroscopy is equivalent to one chest x-ray (0.1 mSv). A simple angioplasty takes about 10 minutes of fluoroscopy time. "One chest x-ray equals one angioplasty or three heart catheterizations," said Dr. Ansel.

While wearing protective gear can help minimize exposure, some risk remains. Lead aprons are 95% effective at blocking ionizing radiation. "But 5% [exposure] is a lot. If you look at the amount of x-ray you're going to get under the lead apron, what you see is that in 18 years of being in this profession ... 1 out of 100 doctors is going to have cancer or leukemia," said Dr. Ansel.

That's without factoring in environmental sources. Background radiation--from space and naturally occurring radioactive materials--averages 300 mrem (which measures radiation dose) per year. That's equivalent to having 30 chest x-rays in that same amount of time.

Add to this the fact that endovascular procedures take much longer than cardiac procedures, and the problem is magnified, Dr. Ansel added.

Using radiation protection devices, however, can help lessen the dosage received. There are now on- and under-table shields, special radiation-blocking hand pads, and leaded safety glasses available.

In addition, vascular surgeons can help minimize their exposure by being aware of their position in relation to the x-ray beam.

Several factors affect the amount of radiation exposure received in the vascular laboratory. These include patient size, number and strength of x-rays, location of the image intensifier, magnification, collimation, and the distance of the surgeon from the table.

Most of the radiation to which vascular surgeons are exposed comes, surprisingly, not from the image intensifier, which sends out electrons in a straight line, but from scatter due to the size of the patient. "Bigger patients give you more scatter," said Dr. Ansel.

Dr. Ansel disclosed that he has a financial interest in Vascular Performance Products LLC, which makes radiation protection products.