麻豆传媒

The cardiac catheterization laboratory can achieve large reductions in radiation exposure for patients and staff through changes to protocols and culture, a single-center's experience showed.

Such changes dropped the mean radiation exposure of patients by 40% over a 3-year period, from a cumulative skin dose of 969 mGy to 568 mGy across interventional procedures, Kenneth A. Fetterly, PhD, of the Mayo Clinic in Rochester, Minn., and colleagues found.

Radiation scatter to cath lab staff, which is directly proportional to patient dose, likely fell by a similar degree, the group reported in the August issue of JACC: Cardiovascular Interventions.

"This work demonstrates that a philosophy of radiation safety, implemented through a collection of sustained practice and x-ray system changes, can result in a significant decrease in the radiation dose administered to patients," they wrote.

"Although the patient dose associated with invasive cardiovascular procedures is below the level that is known to be associated with elevated cancer risk, it is assumed that even low levels of radiation have a proportionate risk and that dose should be minimized as much as possible," they said.

Progressive changes carried out at the Mayo Clinic from 2008 to 2010 for radiation safety included:

• Establishment of a multidisciplinary cath lab radiation safety committee
• Radiation dose announcements during the procedure at 3,000 mGy intervals to elevate awareness and minimize high-dose procedures
• Putting the radiation dose in the final report of the procedure
• Compulsory fellows training on x-ray imaging and radiation safety
• Standardized x-ray protocols
• Increased spectral filtration for acquisition imaging
• Setting the default fluoroscopy program to low
• Fluoroscopy frame rate reduced to 7.5 frames per second
• Reduced acquisition detector target dose

The culture of the cath lab also had to change, the researchers noted.

"To reduce patient radiation dose requires that the physician's expectations change from a desire for excellent image quality to a desire for low radiation dose and acceptance of clinically adequate image quality," Fetterly's group noted.

Over the 3-year period, the cumulative skin dose -- calculated directly from numbers reported by the x-ray system -- fell 41% for percutaneous coronary interventions, 34% for structural heart procedures, and 53% for vascular angiographic and interventional procedures.

That resulted from a reduction in both image acquisition radiation dose to the skin by 46% and in fluoroscopy skin dose by 33%.

Altogether, the proportion of the 18,115 procedures done that had a cumulative skin dose exceeding the high-dose threshold of 6,000 mGy dropped from 0.33% in the first year of the intervention to 0.13% in the third year.

"This reduction was accomplished in a clinical environment with several x-ray systems, 27 physician operators, and 65 fellows-in-training while performing a wide variety of cardiovascular procedures," the researchers noted.

Of the 21 physicians who practiced in the cath lab across the entire study period, all but two cut their patient radiation dose in the range 22% to 69%. The other two increased patient radiation dose by 6% and 33%, respectively.

The researchers noted large interpatient and interprocedure variability in radiation dose that would tend to mask changes.

The study couldn't determine the absolute effect of any single change among the many instituted during the 3-year period, nor did it estimate the impact on lower dose for individual patients.

From the American Heart Association:

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