Research articleRadiation dose reduction initiative: Effect on image quality in shoulder CT imaging

•Significant CT dose reduction can produce adequate subjective image quality.•Lower BMI is associated with larger dose reduction.•More DLP reduction is achieved in women than men.ObjectiveTo evaluate the impact of a radiation dose-reduction initiative on shoulder CT examinations.MethodsA consecutive series of 120 shoulder CT examinations (60 pre-/60 post-dose reduction) were analyzed under an IRB-approved retrospective review. Two radiology residents performed quantitative signal-to-noise ratio (SNR) calculations of multiple tissue types at pre-defined slice positions. Two attending radiologists ranked quality on a Likert scale of 1-5 (1-poor, 5-excellent). ANCOVA was used to test the difference in mean scores. Intraclass and kappa correlations were obtained.ResultsThere were 34 women and 86 men (age 43 ± 12 years, mean ± SD) with BMI of 29 ± 7 kg/m2. Mean volume CT dose index (CTDIvol) and dose-length product (DLP) was reduced from 71 ± 28 to 30 ± 20 mGy and 1709 ± 756 to 658 ± 479mGy-cm, respectively. Lower BMI was associated with larger dose reduction. DLP in females was 29% lower than males. For SNR and quality, observer agreement varied from 0.43-0.84. Significant reductions in SNR were observed in cortex by both observers. There was significant reduction in image quality for Observer 2 (p = 0.03) and not for Observer 1. However, mean subjective quality for Observer 2 remained adequate (3.6/5).ConclusionDespite substantial reductions in radiation doses, mean subjective image quality for shoulder CTs remains adequate.