Objective: To evaluate the feasibility of automatic tube current modulation (ATCM) in craniocervical artery CT angiography with 256-slice CT, while maintaining the image quality.
Methods:  Sixty patients undergoing craniocervical artery CTA were enrolled into this study, and were divided into conventional tube current group (250 mAs, group A, n=30) and low tube current group (ATCM, group B, n=30). The signal-to-noise ratio (SNR), contrast-to noise ratio (CNR), volume CT dose index (CTDIvol) and effective dose (ED) were evaluated respectively.
Results: The mean image SNR was (37.47±9.39) and (36.85±7.96) for group A and group B respectively, and was not significantly different (P=0.79). The mean image CNR was (32.13±9.06) and (31.86±7.66) for group A and group B respectively, and was not significantly different (P=0.90). The CT volume dose index (CTDI) was 16.5 mGy and 410.55±0.94mGy for group A and group B respectively, and was significantly different (P＜0.001). The radiation dose decreased 36.1% in ATCM.
Conclusions: Compared with 250 mAs tube current, ATCM craniocervical artery CTA can reduce radiation dose, while maintaining image quality.