Background: Computed tomography (CT) is the primary source of nontherapeutic medical radiation exposure. Radiation exposure is associated with an increased risk of cancer mortality. Although the risk of cancer mortality is negligible in comparison with that of trauma mortality in high-risk patients, the balance of risk versus benefit in patients with less severe mechanisms of injury is unknown.
Methods: This observational cohort study using a trauma center registry included blunt trauma patients prospectively triaged to an intermediate risk group (level II). Radiation dose was calculated using average dosage for each CT scan. Age-adjusted attributable radiation risk for cancer mortality was calculated using Biological Effects of Ionizing Radiation VII data.
Results: Six hundred forty-two level II trauma patients were analyzed, with a mean age of 43.8 years and a median Injury Severity Score of 8. Patients received a median radiation effective dose of 24.7 mSv in the first 24 hours of medical evaluation. Higher Injury Severity Score was associated with greater total radiation dose. Of the four deaths, all were 80 years or older with intracranial injuries. The estimated risk of cancer death attributable to CT exposure was 0.1%.
Conclusions: The risk of mortality from trauma is six times higher than the estimated risk of radiation-induced cancer mortality in intermediate level trauma patients. The mortality due to trauma is greatest in older patients, suggesting lower clinical suspicion is needed to warrant CT studies in this population. Efforts to reduce radiation exposure to trauma patients should focus on young patients with minor injuries.
From the Departments of Emergency Medicine (T.A.L., M.F.B.), Mayo Medical School (K.M.T.), Radiology (J.M.K.), Surgery (M.D.S.), and Radiation Oncology (N.N.I.L.), Mayo Clinic, Rochester, Minnesota.
Submitted for publication February 23, 2010.
Accepted for publication April 5, 2010.
Presented at American College of Emergency Physicians (ACEP) Scientific assembly, Boston, MA; October 5, 2009.
Published as abstract: Thompson K, Laack N, Kofler J, Bellolio M, Sawyer M, Laack T. Ionizing radiation from computerized tomography during evaluation of intermediate-risk trauma patients. Ann Emerg Med. 2009;54(suppl S):S12.
Address for reprints: Torrey A. Laack, MD, Department of Emergency Medicine, Mayo Clinic Rochester, 200 First Street SW, Rochester, MN 55905; email: Laack.firstname.lastname@example.org.