Study: ED CT protocol linked with excess rad exposure
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Given the increasing use of whole-body CT scans, coupled with heightened concerns about radiation exposure, Stephen Asha, MD, of the emergency department at St. George Hospital in Sydney, Australia, and colleagues sought to measure the proportion of patients exposed to radiation dose in excess of 20 mSv before and after the introduction of a panscan protocol for blunt trauma. The researchers also aimed to quantify missed injuries before and after the introduction of the protocol.
St. George Hospital introduced the protocol in March 2007, basing panscan criteria on mechanism of injury, initial vital signs and injury pattern. The decision to implement the protocol was partially based on the hypothesis that when patients in this population were not scanned in the ED, many underwent delayed CT scanning. Thus, it was assumed that radiation exposure might not increase.
Asha and colleagues reviewed the trauma database and examined data for 1,280 patients: 656 patients six months prior to the introduction of the protocol and 624 patients six months after the introduction of the protocol.
“After the introduction of the protocol we found a higher absolute risk (20 percent vs. 12 percent) of receiving a higher radiation dose compared with before,” wrote Asha and colleagues. Average estimated radiation exposure was 23.9 mSv, with the total dose ranging from 10.2 mSv to 30.0 mSv. These odds were higher among patients older than age 30 and those not discharged home compared with those who were.
“Before the introduction of the protocol, there were six patients with missed head, neck or torso injuries compared with four patients after…It is not clear that this increased risk of exposure to a higher radiation dose was offset by a clinical benefit,” Asha et al wrote.
However, the researchers found that there was an increase in the percentage of patients transferred directly to the operating room after the introduction of the panscan protocol. They noted that other potential benefits of the panscan protocol—reduced need for admission, reduced hospital stay and costs—were not measured in the study. Different scanning protocols and improved CT technology could lead to dose reductions, according to Asha et al.
The researchers concluded by emphasizing that the increased risk of exposure to a radiation dose in excess of 20 mSv was similar regardless of age or injury severity.