Purpose: This study was performed to calculate and analyze the effective radiation doses from computed tomography (CT) and radiologic intervention in patients in the emergency department (ED) with trauma critical pathway (CP) activation and further to estimate the lifetime attributable risks (LARs) for the incidence of and mortality from cancers induced by the radiation dose. Methods: Through a retrospective electrical chart review of 104 injured patients who trauma critical pathway were activated from November 2012 to March 2013, we calculated effective radiologic doses by taking the product of the dose-linear product of the scan and the conversion coefficient. After a determination of the image results, we divided the patients into two groups, negative or positive, and calculated the effective dose for each group. With these results, we estimated the LARs for the incidence of and the mortality from cancers by using the table in the Biologic Effects of Ionizing Radiation (BEIR)-VII report. Results: A total of 76 patients were enrolled. The mean age was $49.0{pm}8.5$ years. The mean injury severity score (ISS) was $12.7{pm}8.4$. The cumulative effective dose (CED) for individual patients varied from 2.8 mSv to 238.8 mSv, and the mean was $47.6{pm}39.9$ mSv. The CED in patients with an $ISS{geq}16$($63.2{pm}26.6$ mSv) was higher than that of patients whose ISS<16($33.5{pm}23.1$ mSv) (p<0.001). The CED in patients who were treated with surgery or intervention($69.0{pm}45.2$ mSv) was higher than that of patients who were treated conservatively($33.6{pm}22.4$ mSv) (p<0.001). The LARs for cancer incidence and mortality were $328.5{pm}308.6$ and $189.0{pm}159.3$ per 100,000 people, respectively. Conclusion: The CED and the LAR for trauma CP-activated patients in the ED were significant, so efforts should be made to decrease the effective dose received by severely injured patients.