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Objective: The purpose of this study was to assess knowledge and attitudes about radiation from CT among emergency department patients with symptoms prompting CT who were stratified on the basis of demographic variables, pain, and perceived illness., Subjects and Methods: This survey study was based on three knowledge and three attitude questions asked of patients who underwent any CT examination from June 23 through July 31, 2008. Data were analyzed with chi-square for categoric data and the Student's t test or analysis of variance for continuous data., Results: The survey was completed by 383 patients (mean age, 48 ± 18 years; 60% women; 40% black; 52% white; 8% other race). In answering the three knowledge-based questions, 79% and 83% of patients correctly estimated their risk of cancer from chest radiography and CT, respectively, as none, small, or very small. Patients who were white, more educated, and had lower pain scores were more likely to be correct. Only 34% of all patients correctly thought that CT gave more radiation than chest radiography; the more educated patients were more likely to be correct. In answering the three attitude questions, 74% of patients believed having their condition diagnosed with CT was more important than worrying about radiation. Patients preferred a better test with more radiation, although 68% wanted their physician to take the time to discuss the risk and benefits rather than using their judgment to order the best test. Privately insured patients preferred to have their condition diagnosed with CT rather than worry about radiation. Blacks and patients with less pain wanted the risks and benefits explained at the expense of time. Whites preferred a more definitive test at the expense of more radiation., Conclusion: Patients did not estimate the risk of development of cancer from their imaging examinations as high and were more concerned about having their condition diagnosed with CT than about the risk of future cancer. Knowledge and attitudes differed by age, race, education, insurance status, and pain level but not by sex, body mass index, or perceived seriousness of condition.

Objective: "Triple rule-out" coronary CT angiography (CTA) using 64-MDCT technology is a new approach for evaluating emergency department patients presenting with symptoms suggestive of acute coronary syndrome (ACS). Our objective was to evaluate the reduction in effective radiation dose through the use of tube current modulation in patients who underwent a triple rule-out coronary CTA evaluation and to document how effective radiation dose was impacted by patient age, sex, and body mass index (BMI)., Materials and Methods: A retrospective analysis of triple rule-out coronary CTA examinations performed on a 64-MDCT scanner was ordered on a prospective cohort of 267 consecutive low- to moderate-risk emergency department patients with suspected ACS from a single university hospital between October 2006 and March 2008. Tube current modulation was generally used in patients with heart rates below 65 beats per minute during the second half of the study period as a way to reduce radiation exposure. We calculated effective radiation exposure using actual patient coronary CTA scanning parameters by age, sex, and BMI., Results: Among the 172 patients evaluated without tube current modulation, effective dose averaged (+/- SD) 18.0 +/- 5.6 mSv (range, 9.9-31.3 mSv). Of the 95 patients who underwent CTA examination with tube current modulation, effective dose was significantly lower at 8.75 +/- 2.64 mSv (range, 5.4-16.6 mSv; p < 0.0001) and image quality was better (p < 0.0001) as compared with examinations without tube current modulation. There were no significant radiation differences by patient age, but tube current modulation decreased radiation exposure by at least half. Among the studies in which tube current modulation was not used, women received less radiation than men (17.0 vs 19.5 mSv, respectively; p < 0.001). For the studies with tube current modulation, there were no radiation differences by sex. Obese patients received significantly more radiation than overweight and normal-weight patients in the non-tube current modulation groups (20.9 mSv vs 15.0 and 14.9 mSv, respectively; p < 0.0001) and in the tube current modulation groups (10.3 mSv vs 7.6 and 7.1 mSv, p < 0.0001)., Conclusion: The overall effective radiation dose for triple rule-out coronary CTA was reduced by more than 50% with ECG-based tube current modulation without loss of image quality. Tube current modulation should be used for triple rule-out coronary CTA examinations whenever possible.