低管电压联合自动管电流调制技术在下肢CT血管成像中的应用

摘要

Objective To investigate the feasibility of ensuring image quality while decreasing the radiation dose with low tube voltage setting combined with automatic tube current modulation (ATCM) in the detection of lower limb CT angiography. Methods A total of 90 patients with suspected lower limb ischemia, who admitted to the First Hospital of Changsha from March 2015 to September 2016, were selected and divided into the 120 kV group, 100 kV group and 80 kV group according to tube voltage setting, with 30 patients in each group. For the three groups, other scan parameters and contrast injection protocol were similar. The images of the three groups were reconstructed, measured and graded, and effective radiation dose were calculated. Results The volume CT dose index (CTDIvol) and effective radiation dose of the 120 kV group, 100 kV group and 80 kV group were respectively (8.2 ± 0.9) mGy, (6.7 ± 1.0) mGy, (5.9±1.1) mGy and (5.2±0.7) mSv, (3.9±0.8) mSv, (3.5±0.7) mSv. There were significant differences in CTDIvol and ED among 3 groups (P<0.01). Compare with the 120 kV group, the effective radiation dose of the 100 kV group decreased for 25.0%, and compared with the 100 kV group, the effective radiation dose of the 80 kV group decreased for 10.3%.The image quality scores for 1-4 points were respectively 0, 0, 9, 21 patients in the 120 kV group, 0, 0, 11, 19 patients in 100 kV group, and 0, 2, 15, 13 patients in 80 kV group. There was no significant difference in image quality score be-tween 120 kVgroup and 100 kV group (P>0.05). Conclusion 100 kV low tube voltage setting combined with ATCM technology can reduce the radiation dose as far as possible, in the premise of ensuring the clinical diagnosis.%目的 探讨在下肢血管成像(CTA)检查中,联合应用低管电压及自动管电流调制(ATCM)技术在降低辐射剂量的同时,保证图像质量的可行性.方法 收集2015年3月至2016年9月间,因下肢血管疾病在长沙市第一医院进行下肢CTA的患者共90例,按照管电压不同将其分为120 kV组、100 kV组、80 kV组,每组30例,其余扫描条件及比较剂注射方案完全一致.对三组患者的图像进行重建、测量和图像质量评分,并计算有效辐射剂量.结果 120 kV组、100 kV组和8 kV组患者的容积CT剂量指数(CTDIvol)分别为(8.2±0.9)mGy、(6.7±1.0)mGy和(5.9±1.1)mGy,有效剂量(ED)分别为(5.2±0.7)mSv、(3.9±0.8)mSv和(3.5±0.7)mSv,三组间比较差异均有显著统计学意义(P<0.01);与120 kV组相比,100 kV组患者的ED下降25.0%,80 kV组与100 kV比较,ED下降10.3%.120 kV组图像评分1~4分的分别为0例、0例、9例、21例,100 kV组分别为0例、0例、11例、19例,80 kV组分别为0例、2例、15例、13例.120 kV组与100 kV组图像质量评分比较差异无统计学意义(P>0.05).结论 100 kV低管电压联合ATCM技术能在保证临床诊断需求的前提下,尽可能地降低辐射剂量.