['The use of high-cost imaging has increased worldwide, contributing to increased healthcare expenditures. Without proper quality verification, the installation of used imaging equipment may lead to wasteful increases in cost due to ineffective and poor-quality imaging that requires repeat scans.', 'To examine the relationship between the use of new or used computed tomography (CT) scanners and image retake rates to evaluate the comparative quality of used and new CT scanners.', 'This was a retrospective cohort study of patients who first underwent CT from January 1 to June 30, 2008 (n = 258,572). Data were obtained by linking the Health Care Institution Registration Data with the Korean National Health Insurance Claims Database. Image retake rates within 30, 60, 90, and 180 days after the first CT scan were calculated, and differences in the image retake rate by new versus used CT scanners were assessed.', 'After adjusting for confounders, use of a used CT scanner for the first scan increased the odds of retake within 30 days (odds ratio [OR]: 1.34, 95% confidence interval [CI]: 1.22-1.48), 60 days (OR: 1.59, 95% CI: 1.47-1.72), 90 days (OR: 1.48, 95% CI: 1.38-1.59), and 180 days (OR: 1.38, 95% CI: 1.30-1.46) compared with use of a new CT scanner. Such results were evident in scans of the spine, abdomen, chest, and face or skull base.'] Do relationship between the use of new or used computed tomography scanners and image retake rates in South Korea?