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.