Reduction of radiation dose according to the type of technology used in cardiac computed tomography

Abstract

In recent years, cardiac computed tomography (CT) has undergone numerous technological advancements aimed at achieving an improvement in the radiation dose of the patient studied. However, the effectiveness of these advancements is largely unknown in daily practice. The present study aims to investigate the magnitude of the radiation dose that a patient receives during cardiac CT in daily practice with a 64-slice CT vs. 80 detector row and 160-slice CT. Methods: Data from 199 cardiac CT in total performed at our institution was analyzed. The first 100 consecutive cardiac CT with the Toshiba AquilionTM 64 (TA-64) scanner during the first semester of year 2009 were analyzed, and the remaining 99 also during the first semester but of year 2019, and made with the Canon AquilionTM PRIME SP (CA-P) system. The main indication for cardiac CT was the anatomical evaluation of coronary arteries due to chest pain (91 patients, 46% of cases) and silent ischemia (49/24). In both periods, a retrospective acquisition of the full cardiac volume was performed. The main radiation value evaluated in each cardiac CT and used as the primary result of our study was the total dose-length product (DLP) and the effective dose (ED). Results: The median DLP of the patients studied in the TA-64 was 1140 mGy.cm (Q1: 1020 mGy.cm, Q3: 1300 mGy.cm) vs. 364.8 mGy.cm (Q1: 244.7 mGy.cm, Q3: 482 mGy.cm) of the CA-P (p<0.0001), and the median of the DLP-ED was 15.9 mSv (Q1: 14.2 mSv, Q3: 18.2 mSv) vs. 5.1 (Q1: 3.4 mSv, Q3: 6.7 mSv), respectively (p<0.0001). In turn, the median of the tube current in the TA-64 group was 450 mA (Q1:400 mA, Q3: 450 mA) vs. 568 mA (Q1: 472 mA, Q3: 580 mA) of the CA-P (p<0.0001), and the median of the tube voltage was 120 kV (Q1: 120 kV, Q3: 120 kV) vs. 100 kV (Q1: 80 kV, Q3: 100 kV), respectively (p<0.01). Furthermore, there were no differences when evaluating the technical quality of the images obtained according to the type of tomography used (regular study quality 6 (7%) cases of 81 patients evaluated in the TA-64 group vs. 4 (4%) of 99 individuals in the CA-P group, p=0.32). Conclusions: This work demonstrates a considerable reduction in exposure to ionizing radiation in cardiac CT performed with state-of-the-art technology, without generating detriment to the quality of the images obtained.