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Potentially harmful radiation doses occur in 1 of 14 PAD procedures
One in 14 patients who undergoes endovascular intervention for lower-extremity peripheral artery disease receives a radiation dose large enough to cause tissue injury, researchers reported.
“We determined that 7% of lower-extremity endovascular interventions expose patients to > 500 Gy x cm2, a threshold above which follow-up is indicated” by the National Council on Radiation Protection and Measurements, Andrew M. Goldsweig, MD, from the division of cardiovascular medicine, University of Nebraska Medical Center, and colleagues wrote.
Goldsweig and colleagues obtained data on radiation dosage, defined as dose-area product, from 17,174 lower-extremity endovascular procedures at 73 sites documented in the National Cardiovascular Data Registry Peripheral Vascular Intervention Registry.
The researchers determined the proportion of procedures exceeding 500 Gy x cm2 and identified patient and procedural factors associated with elevated dose-area product.
Patient dose-area product was more than 500 Gy x cm2 in 7% of procedures, according to the researchers.
The predictor of elevated dose-area product with the greatest magnitude of effect was more proximal lesion location, Goldsweig and colleagues wrote. Other significant predictors, in order of magnitude of effect, were bifurcation lesion, male sex, diabetes, hypertension, prior PCI, elevated lesion length and elevated BMI.
Predictors of decreased dose-area product included antegrade vascular access, critical limb ischemia and increasing age, the researchers wrote.
“Radiation dosage with the potential for tissue injury occurs in 1 of every 14 patients undergoing lower extremity endovascular interventions, and all such patients are exposed to the potential for subsequent malignancy,” the researchers wrote. “Preprocedural assessment of patients’ risk for elevated radiation dosage may allow targeted use of radiation mitigation strategies in patients at increased risk for elevated exposure.”
In a related editorial, Charles E. Chambers, MD, from Hershey Medical Center in Pennsylvania, wrote that limitations include that cumulative air kerma, a better predictor of skin injury than dose-area product, was not reported, and that “the lack of data entry oversight and case exclusion for incomplete data create potential bias.”
“As peripheral intervention expands both in potential procedures and in potential operators, quality oversight must similarly expand to assess best practices to ensure optimal patient care,” Chambers wrote. – by Erik Swain
Disclosures: The authors and Chambers report no relevant financial disclosures.
Perspective
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It will be a surprise to most practitioners that such a significant proportion of what are considered routine procedures result in consequential doses to their patients and thus, by inference, to the practitioners and their assistants.
Dose-area product is not the best way to measure risk, but it is an easily understood (by non-physicists) measure of how much radiation was used during a procedure. The whole area of radiation biology is a field very much in transition. In the same manner that the response to a period of exposure to the sun is very much different between individuals, so it is with response to radiation in the diagnostic X-ray wavelength. Patients and staff are all uniquely predisposed, and there are other mitigating factors such as exposure to other carcinogens, accumulation of medical imaging, air travel, etc. Having said that, the 500 Gy x cm2 threshold for stochastic events (those that occur by chance) were created on best available information by experts in the field and it will be years before more patient-specific data will be available.
There are a number of methods to mitigate risk to patients from radiation during endovascular procedures for PAD, all of them cumulative. First of all is the recognition that even though radiation is invisible and the effects are delayed, radiation risks are real. Therefore, physicians have to be realistic about balancing pride and ego regarding finishing a case vs. these undefinable radiation risks to their patients, themselves and staff. Measures to reduce radiation dose include avoiding magnification and digital acquisition (100x dose per frame) except where necessary, and using different dose modes: low, mid and high depending on clinical need. Creation of protocols specific to the procedure (ie, contrast, stent, vessel size), done in concert with a physicist and the vendor can make a huge difference.