Most operators realize that radiation exposure in the cath lab puts them, plus their staff, at risk of potential cancers in the future. What they may not know is that a number of strategies exist to reduce exposure, and many don’t cost a dime.
An invisible danger
Radiation exposure is an occupational hazard for interventional cardiologists, electrophysiologists, other subspecialists and their coworkers. Intellectually they know it, but in day-to-day practice it may not rise to the top tier of priorities, particularly in the bustle of a busy catheterization laboratory. “You can’t touch radiation and the consequences aren’t tangible,” observes Charles Chambers, MD, an interventional cardiologist at Hershey Medical Center in Pennsylvania and a champion of radiation safety for patients and physicians.
The potential health consequences are not immediate. But they are accumulative, a concern that grows as cardiologists take on longer and more complicated cases. And operators who perform diagnostic angiography and PCIs are not the only ones at risk. Percutaneous treatments such as aortic and mitral valve replacements for valvular diseases, radiofrequency ablations for atrial fibrillation and interventions for chronic total occlusions and peripheral artery disease repeatedly expose more cardiologists to radiation for longer durations.
“Procedures are becoming longer and more radiation-intensive,” says Shikhar Agarwal, MD, an interventional cardiologist at the Cleveland Clinic’s Heart and Vascular Institute. “Unless we become very cognizant of the radiation dose to us, some of us may get burned in terms of developing radiation-related diseases. It is critical that we do whatever is necessary to minimize dose to the operators.”
A few years ago that message may have fallen on deaf ears. But the publication of reports describing head and neck cancers in career interventionalists captured the attention of some cardiologists and provided fodder for radiation safety advocates. Many physicians credit Ariel Roguin, MD, PhD, an interventional cardiologist at the Technion-Israel Institute of Technology, for first raising the call of—if not alarm—extreme caution.
In 2012, Roguin and colleagues documented nine cases of brain cancer in interventional cardiologists, and expanded that list to brain and neck cancers in 23 interventional cardiologists, six interventional radiologists and two electrophysiologists (Am J Cardiol 2013;111:1368-1372). Ominously, of the 26 cases where they obtained information on tumor location, 22 occurred on the left side—the side that more frequently is exposed to radiation during interventional procedures.
Start with the source
With today’s digital imaging systems, physicians can customize protocols in ways that could reduce radiation exposure without diminishing image quality. The catch is, they may not know it. Agarwal and his colleagues at the Cleveland Clinic put that idea to the test by instituting measures to lower operator radiation exposure. One component dealt with a change to the default setting in imaging devices.
“The equipment has a big role to play in terms of reducing radiation,” he says. Case in point: Their team cut radiation doses by 22 percent for diagnostic catheterizations and by 32 percent for PCIs by leveraging widely available technology (Circ Cardiovasc Interv online Aug. 5, 2014).
They conducted a retrospective before-after assessment of an initiative that reduced the default fluoroscopic frame rate from 10 to 7.5 frames per second. The program also emphasized the use of low-dose acquisitions, best radiation practices and monthly review of radiation dosimetry of each interventional cardiology fellow by the cath lab director.
The results? Median total air kerma during diagnostic catheterizations after the changes was 625 mGy vs. 798 mGy before and median total air kerma during PCIs was 1,675 mGy vs. 2,463 mGy, respectively.
“We didn’t ask people to conform,” Agarwal notes. “We just said. ‘We are going to make these changes on the equipment. If you think they are not OK then please go back to your practice.’ Most people did not even realize they were doing low-dose fluoroscopy … and low-dose acquisition.”
Some cardiologists balk at making modifications for fear that poor imaging will compromise patient care. The Cleveland Clinic effort did not assess quality head on. Instead they used the success of the PCI as a surrogate, Agarwal says, which was identical in the two periods.