Purpose: To compare the delivered radiation dose between a low-dose hip computed tomography (CT) scan protocol and traditional hip CT scan protocols (i.e., "traditional CT").
Methods: This was a retrospective comparative cohort study. Patients who underwent hip-preservation surgery (including arthroscopy, surgical hip dislocation, or periacetabular osteotomy procedures) at our institution between 2016 and 2017 were identified. Patients were excluded if they had a body mass index (BMI) greater than 35, they underwent previous surgery, or a radiation dose report was absent. The low-dose group included patients who underwent hip CT at our institution using a standardized protocol of 100 kV (peak), 100 milliampere-seconds (mAs), and a limited scanning field. The traditional CT group included patients who had hip CT scans performed at outside institutions. The total effective dose (Ehip), effective dose per millimeter of body length scanned, patients' age, and patients' BMI were compared by univariate analysis. The correlation of Ehip to BMI was assessed.
Results: The study included 41 consecutive patients in the low-dose group and 18 consecutive patients in the traditional CT group. Low-dose CT resulted in a 90% reduction in radiation exposure compared with traditional CT (Ehip, 0.97 ± 0.28 mSv vs 9.68 ± 6.67 mSv; P < .0001). Age (28 ± 11 years vs 26 ± 10 years, P = .42), sex (83% female patients vs 76% female patients, P = .74), and BMI (24 ± 3 vs 24 ± 3, P = .75) were not different between the 2 groups. Ehip had a poor but significant correlation to BMI in the low-dose CT group (R2 = 0.14, slope = 0.03, P = .02) and did not correlate to BMI in the traditional CT group (R2 = 0.13, P = .14).
Conclusions: A low-dose hip CT protocol for the purpose of hip-preservation surgical planning resulted in a 90% reduction in radiation exposure compared with traditional CT.
Level of evidence: Level II, diagnostic study.
Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.