Dose levels low for interventionist during CT-guided procedures

Radiation exposure during CT-guided interventions (CTGIs) is generally low for the interventionist as long as general rules and precautions are followed, according to a study published online July 31 in the Journal of the American College of Radiology.

While doses overall were relatively low, authors Nils Rathmann, MD, of University Medical Center Mannheim at Heidelberg University in Mannheim, Germany, and colleagues did find that more complex interventions resulted in higher dose, suggesting that inexperienced radiologists should focus on less-complex procedures.

Rathmann and colleagues sought to analyze radiation exposure for interventionists since few previous studies have focused on doses for radiologists. There are also issues with trying to use patient dose levels or dose monitoring badges to estimate exposure for interventionists.

“Radiation exposure levels for staff do not necessarily correlate with those of the patient; thus, patient dose measurements (such as dose-area product) cannot be used to determine exposure for personnel,” wrote the authors. “Underestimation of the real, effective dose by official dose monitoring might constitute a problem, because the film badge is usually worn under the lead apron. In this setting, exposure of unprotected body parts such as extremities or the head is not taken directly into consideration.”

For the current study, absolute radiation dose values from 131 CTGIs were analyzed, with dose values collected by thermoluminescent dosimeters positioned on the forehead, thyroid, chest, gonads, hands and feet.

Results showed median whole-body dose was 12 μSv. Modern dual-source CT systems resulted in significantly lower doses compared with 16-slice multi-detector CT with the exception of the forehead. CTGIs rated as more complex featured significantly higher exposure to the radiologist, with the exception of the left hand.

While the doses were fairly low, the authors did report a few dose measurements of more than 1 mSv found in the right hand.

The results of the study show that annual dose limits are not exceeded during CTGI when appropriate shielding is used. “CTGI radiation exposure overall is relatively low for radiologists if the general rules of radiation protection are respected,” wrote Rahmann and colleagues. “The use of planning software, robot support, and navigation tools might further reduce radiation exposure because the radiologist would then not be present in the intervention suite during control scans.”