Background: In 2010, the International Atomic
Energy Agency launched the “3A’s campaign” as an effective tool for primary
cancer prevention. In 2011, the American Association of Physicists in Medicine
recommended the size specific dose estimate (SSDE). Objectives: To audit doses
of Coronary CT Angiography (Coronary CTA) in tertiary care referral center.
Methods: We reviewed 998 consecutive Coronary CTA (from 2007 to 2012). Doses
(CTDIvol mGy), DLP (mGy*cm), effective dose (DLP*0.014, mSv) were on-line
archived. SSDE was estimated retrospectively. Appropriateness score was
evaluated for exams performed from the 2010. Results: Overall median dose per
Coronary CTA was 49.7 mGy for CTDIvol, 55.5 mGy for SSDE, 994.96
mGy*cm for DLP, 13.9 mSv for effective dose. Median DLP decreased over time
(1452.94 in 2007, 1605.56 in 2008, 1113.49 in 2009, 759.99 in 2010, 448.61 in
2011 and 497.88 mGy*cm in 2012, p < 0.0001). SSDE was proportional to the size
dependent factor (SDF); in patients with SDF > 1 (88%) CTDIvol underestimated SSDE (48.49 vs
57.19 mGy), whilst in patients with SDF < 1 (12%) CTDIvol overestimated SSDE (56.46 vs
50.3 mGy). Scans were appropriate in 58%, uncertain in 24%, and inappropriate
in 18% of cases. Doses were similar in appropriate, uncertain or inappropriate
examinations and in excellent-to-good (81%) vs. sufficient-to-poor (19%) image
quality exams. Conclusions: Coronary CTA reference doses can be very
misleading. SSDE can allow individual technique optimization. The dose is
similar in appropriate and inappropriate examinations, and unrelated to image
quality. The rate of inappropriate examinations is still too high even after
dissemination of guidelines.