Anto-mA Technique for Abdominal Enhanced CT Angiography: a feasibility study

Objective To investigate the value of auto-mA technique for reducing radiation dose of abdominal enhanced CT angiography.Methods Fifty patients suspicious of abdominal disease underwent CT volume scanning arranged from 2 mm above the mediastinum to the iliac crest line level,and the scanning included three phases,that was,simple scan phase,arterial phase and venous phase.The patients were divided into two groups of fixed mA(FM) and auto mA(ATCM),of which,the former employed the fixed 300 mA and the latter adopted auto-mA technique.Preliminary experiment was used to change the noise index(NI) to regulate the tube current.The image quality matched well with the radiation dose when NI was 9.10.With the subphrenic abdominal aorta and hepatic portal vein as the observation levels,t-test was used for the statistical analyses of the image quality,image noise and radiation dose by the two mA techniques.Results As for the radiation dose,FM group had its average CTDIvol as 23.68 mGy and average DLP as 597.22 mGy·cm,and ATCM group had its average CTDIvol as 6.44 mGy and average DLP as 154.226 mGy·cm.ATCM group had its values lower than those of FM group by 74.2%,and there was significant difference between them,with the values of t as 45.100 and 112.57 respectively and P0.05.Conclusion The application of auto-mA technique to abdominal enhanced CT angiography makes the radiation dose lowered by 74.2%,with the image quality ensured.