Pelvic Shield Reduces Radiation Exposure for Operators But Increases It for Patients
Draping patients with pelvic lead shielding during transradial coronary angiography reduces radiation exposure to the operator but actually increases the dose to the patient, according to a study published February 3, 2015, ahead of print in Catheterization and Cardiovascular Interventions.
Ariel Roguin, MD, PhD, of the Israel Institute of Technology (Haifa, Israel), and colleagues randomized 332 patients undergoing transradial coronary angiography to have the procedure with pelvic shielding (n = 162)—a 0.5-mm lead apron was laid from the patient’s lower abdomen to upper thigh—or without (n = 160). Digital dosimeters were used to measure scattered radiation as well as doses to the operator and patient.
In cases involving pelvic shielding, operators prepared the femoral and radial artery puncture sites and positioned sterile towels under and on top of the lead apron to allow rapid crossover to transfemoral access if needed. Protective gear utilized by operators included lead aprons, eye glasses, lead thyroid collars, and an overhead acrylic shield with a patient contour cutout.
Pelvic shielding reduced operator radiation dose at 3 exposure sites—under the lead apron, under the thyroid collar, and at the left side of the head. However, the mean patient dose almost doubled when pelvic shielding was used (table 1).
“The predominance of dose to the operator is scatter radiation, while the preponderance of dose to the patient is related to the photons that enter the patient and do not leave—hence the increased dose with the additional lead,” the paper explains.
Shield Not Ready for Universal Adoption
While the increased patient radiation dose is an important and complicated issue, Dr. Roguin and colleagues write, “it is highly unlikely that a dose of 28 μSv would reach a deterministic threshold.”
Among operators, “a typical cumulative 15-year physician working with ionizing radiation exposure around the equivalent of 50 mSv is estimated [to have] a life attributable risk of cancer in the order of magnitude of 1 [occurrence of] cancer in 200 exposed subjects,” the researchers report.
“The interventional cardiologists are subjected to head dose radiation exposure 10- to 20-fold higher than the dose recorded beneath the apron,” they continue, adding, “Thus, there is a balance between two estimated risks for the patient and for the operator. For a patient this is usually a single episode, but some physicians work on a daily basis with radiation performing interventional procedures.”
Due to the uncertain balance between patient and operator risk, pelvic shielding “cannot be adopted universally” the authors write, adding that even so, they now routinely use the strategy to reduce operator radiation exposures. “We currently believe that reducing scatter radiation is of major importance and its benefit [for the operator] outweighs the risk [for the patient],” they say.
Dr. Roguin and colleagues cite additional shielding equipment, such as modified arm boards and disposable radiation shielding pads, as effective tools in reducing radiation exposures in radial procedures but note “these methods require additional equipment and cost.”
Patient, Operator Risks Not Comparable
In a telephone interview with TCTMD, Stephen Balter, PhD, of Columbia University Medical Center (New York, NY), said the use of pelvic lead shielding could prove to be an important strategy for protecting operators and staff at negligible risk to patients.
The increased dose to patients, who may undergo 1 or 2 procedures in a lifetime, does not compare to the decreased dose to cath lab operators, who are exposed repeatedly over many years, he said.
“We are mostly talking about older patients,” Dr. Balter added. “If the issue is long-term cancer risk, this isn’t likely to be very relevant.”
Even so, Charles E. Chambers, MD, of Penn State Milton S. Hershey Medical Center (Hershey, PA), said clinicians are ethically bound to explain the risk to patients. He acknowledged, however, that the issue of informed consent is tricky when dealing with long-term risk from radiation exposure.
“You can tell them that they are getting twice the dosage, which is likely to cause apprehension,” he said in a telephone interview with TCTMD. “Or you can tell them that their risk is probably trivial. This may be true, but we can’t really prove that. You can’t really inform the patient without spinning it one way or another.”
Musallam A, Volis I, Dadaev S, et al. A randomized study comparing the use of a pelvic lead shield during trans-radial interventions: threefold decrease in radiation to the operator but double exposure to the patient. Catheter Cardiovasc Interv. 2015;Epub ahead of print.
- Drs. Roguin, Balter, and Chambers report no relevant conflicts of interest.