Evaluation der Strahlendosis bei Polytrauma-CT-Untersuchungen eines 64-Zeilen-CT im Vergleich zur 4-Zeilen-CT

Abstract

To evaluate radiation exposure in whole-body CT (WBCT) of multiple injured patients comparing 4-row multidetector computed tomography (MDCT) to 64-row MDCT. 200 WBCT studies were retrospectively evaluated: 92 4-row MDCT scans and 108 64-row MDCT scans. Each CT protocol was optimized for the particular CT system. The scan length, CT dose index (CTDI), and dose length product (DLP) were recorded and analyzed for radiation exposure. The mean effective dose was estimated based on conversion factors. Student's t-test was used for statistical analysis. The mean CTDIvol values (mGy) of the thorax and abdomen were significantly reduced with 64-row MDCT (10.2±2.5 vs. 11.4±1.4, p<0.001; 14.2±3.7 vs. 16.1±1.7, p<0.001). The DLP values (mGy×cm) of the head and thorax were significantly increased with 64-row MDCT (1305.9±201.1 vs. 849.8±90.9, p<0,001; 504.4±134.4 vs. 471.5±74.1, p=0.030). The scan lengths (mm) were significantly increased with 64-row MDCT: head 223.6±35.8 vs. 155.5±12.3 (p<0.001), thorax 427.4±44.5 vs. 388.3±57.5 (p<0.001), abdomen 520.3±50.2 vs. 490.8±51.6 (p<0.001). The estimated mean effective doses (mSv) were 22.4±2.6 (4-row MDCT) and 24.1±4.6 (64-row MDCT; p=0.001), resulting in a percentage increase of 8%. The radiation dose per slice of the thorax and abdomen can be significantly decreased by using 64-row MDCT. Due to the technical advances of modern 64-row MDCT systems, the scan field can be adapted to the clinical demands and, if necessary, enlarged without time loss. As a result, the estimated mean effective dose might be increased in WBCT.