Adult exposures from MDCT including multiphase studies: First Italian nationwide survey

Objectives: To evaluate the radiation dose in routine multidetector computed tomography (MDCT) examinations in Italian population. Methods: This was a retrospective multicentre study included 5,668 patients from 65 radiology departments who had undergone common CT protocols: head, chest, abdomen, chest-abdomen-pelvis (CAP), spine and cardiac. Data included patient characteristics, CT parameters, volumetric CT dose index (CTDI_vol) and dose length product (DLP) for each CT acquisition phase. Descriptive statistics were calculated, and a multi-regression analysis was used to outline the main factors affecting exposure. Results: The 75th percentiles of CTDI _vol (mGy) and DLP (mGy cm) for whole head were 69 mGy and 1,312 mGy cm, respectively; for chest, 15 mGy and 569 mGy cm; spine, 42 mGy and 888 mGy cm; cardiac, 7 mGy and 131 mGy cm for calcium score, and 61 mGy and 1,208 mGy cm for angiographic CT studies. High variability was present in the DLP of abdomen and CAP protocols, where multiphase examinations dominated (71 % and 73 % respectively): for abdomen, 18 mGy, with 555 and 920 mGy cm in abdomen and abdomen-pelvis acquisitions respectively; for CAP, 17 mGy, with 508, 850 and 1,200 mGy cm in abdomen, abdomen-pelvis and CAP acquisitions respectively. Conclusion: The results of this survey could help in the definition of updated diagnostic reference levels (DRL). Key Points: • Radiation dose associated with multidetector CT (MDCT) is an important health issue. • This national survey assessed dose exposures of 5,668 patients undergoing MDCT. • Dose indices correlate with BMI, voltage, rotation time, pitch and tube current. • These results may contribute to an update of national diagnostic reference levels.