Division of Abdominal Imaging, Department of Radiology, Institute of Radiation Medicine, Seoul National University College of Medicine, 28 Yeongon-dong, Jongno-gu, Seoul 110-744, Korea.
Radiology. 2012 Nov;265(2):437-47. doi: 10.1148/radiol.12112434. Epub 2012 Sep 25.
To retrospectively determine whether the combined use of automatic tube voltage selection (ATVS) and automatic tube current modulation (ATCM) can effectively reduce radiation dose at contrast material-enhanced liver computed tomography (CT) while maintaining acceptable image quality compared with the use of ATCM alone.
This study was approved by an institutional review board, and informed consent was waived. Three hundred fourteen consecutive patients suspected of having liver disease were divided into three groups. In two groups, both ATVS and ATCM were used (group A1, n=97; group A2, n=101) but with different contrast gain settings; in one group, only ATCM with a fixed tube potential of 120 kV (group B, n=116) was used. Weighted volume CT dose index and dose-length product, contrast-to-noise ratios (CNRs), and mean image noise were assessed. Qualitative analysis was performed by two board-certified radiologists and one radiology resident. Statistical analysis was performed by using the one-way analysis of variance test, two-tailed paired t test, Kruskal-Wallis test, and noninferiority test.
In groups A1 and A2, a significant dose reduction was obtained compared with that in group B (P<.0001). The mean dose reduction was 20% in group A1 and 31% in group A2. Furthermore, CNRs were significantly higher in groups A1 and A2 than in group B (P<.0001). Despite the higher image noise in groups A1 and A2, the overall image quality was acceptable.
Compared with the use of ATCM alone, the combined use of ATVS and ATCM allowed reduction of radiation exposure while maintaining good image quality at contrast-enhanced liver CT.
回顾性分析自动管电压选择（ATVS）联合自动管电流调制（ATCM）与单纯使用 ATCM 比较，能否在增强肝脏 CT 检查中有效降低辐射剂量，同时保持可接受的图像质量。
本研究经机构审查委员会批准，且豁免了知情同意。314 例连续疑似肝脏疾病患者分为 3 组。2 组均使用 ATVS 和 ATCM（组 A1，n=97；组 A2，n=101），但对比增益设置不同；1 组仅使用固定管电压 120 kV 的 ATCM（组 B，n=116）。评估加权体 CT 剂量指数和剂量长度乘积、对比噪声比（CNR）和平均图像噪声。由 2 位放射科认证医师和 1 位放射科住院医师进行定性分析。采用单因素方差分析、双侧配对 t 检验、Kruskal-Wallis 检验和非劣效性检验进行统计学分析。
与组 B 比较，组 A1 和组 A2 剂量明显降低（P<.0001）。组 A1 平均剂量降低 20%，组 A2 降低 31%。此外，组 A1 和组 A2 的 CNR 明显高于组 B（P<.0001）。尽管组 A1 和组 A2 的图像噪声较高，但总体图像质量可接受。
与单纯使用 ATCM 比较，ATVS 联合 ATCM 可在增强肝脏 CT 检查中降低辐射暴露，同时保持良好的图像质量。
