Patient perceptions of computed tomographic imaging and their understanding of radiation risk and exposure.

Study Objective: We describe patient perceptions of computed tomography (CT) and their understanding of radiation exposure and risk.

Methods: This was a cross-sectional study of acute abdominal pain patients aged 18 years or older. Confidence in medical evaluations with increasing levels of laboratory testing and imaging was rated on a 100-point visual analog scale. Knowledge of radiation exposure was ascertained when participants compared the radiation dose of one abdomen-pelvis CT with 2-view chest radiography. To assess cancer risk knowledge, participants rated their agreement with these factual statements: "Approximately 2 to 3 abdominal CTs give the same radiation exposure as experienced by Hiroshima survivors" and "2 to 3 abdominal CTs over a person's lifetime can increase cancer risk." Previous CT was also assessed.

Results: There were 1,168 participants, 67% women and mean age 40.7 years (SD 15.9 years). Median confidence in a medical evaluation without ancillary testing was 20 (95% confidence interval [CI] 16 to 25) compared with 90 (95% CI 88 to 91) when laboratory testing and CT were included. More than 70% of participants underestimated the radiation dose of CT relative to chest radiography, and cancer risk comprehension was poor. Median agreement with the Hiroshima statement was 13 (95% CI 10 to 16) and 45 (95% CI 40 to 45) with the increased lifetime cancer risk statement. Seven hundred ninety-five patients reported receiving a previous CT. Of 365 patients who reported no previous CT, 142 (39%) had one documented in our electronic medical record.

Conclusion: Patients are more confident when CT imaging is part of their medical evaluation but have a poor understanding of the concomitant radiation exposure and risk and underestimate their previous imaging experience.