Objective To compare the effects of adjusting tube voltage and adaptive statistical iterative reconstruction （ASIR）-V percentage on dose reduction in contrast-enhanced infant abdominal CT. Methods Twenty infants who received contrast-enhanced abdominal CT with 80 kVp and 40% ASIR-V were retrospectively analyzed（common group）. Forty age-，sex-，and weight-matched infants were recruited prospectively and divided into two groups ：low tube voltage group scanned with 70 kVp and 40% ASIR-V and high ASIR-V percentage group scanned with 80 kVp and 60% ASIR-V. The CT dose index（CTDI），dose length product （DLP），size-specific dose estimate（SSDE）and effective dose（ED）of single phase were recorded and calculated. In addition，two radiologists evaluated the image quality score using five-point method subjectively. Interobserver agreements for image quality evaluating was assessed by intra-class correlation coefficient（ICC）. One-wayANOVA was used to compare the dose parameters among three groups．Bonferroni test was used for further pairwise comparison. Results Sex，age and weight showed no statistically significant difference among the three groups （P ＞ 0.05）. The CTDI were（0.51±0.06）mGy、（0.34±0.03）mGy、（0.31±0.04）mGy in common group，low tube voltage group and high ASIR-V percentage group，respectively. DLP were（8.94±1.40）mGy-cm、（5.85± 0.72）mGy-cm、（5.53±0.75）mGy-cm. SSED were（1.15±0.12）mGy、（0.76±0.06）mGy、（0.68±0.07）mGy. ED were（0.35±0.08）mSv、（0.26±0.05）mSv、（0.21±0.03）mSv. Image quality score were 4.26±0.30，3.74±0.28 and 3.50±0.53. All dose parameters and image quality score were statistically significantly different among the three groups（P ＜ 0.001）. Radiation dose and image quality score of low tube voltage group and high ASIR-V group were significantly decreased than these of common group（P ＜ 0.001），but image quality score met the diagnostic criteria in all groups（≥ 3）. Image quality score had no statistically significant difference between low tube voltage group and high ASIR-V group（P ＞ 0.05）. Conclusion In contrast-enhanced infant abdominal CT, on the basis of conventional 80 kVp, ASIR-V 40% , reducing tube voltage by 10 kVp and increasing ASIR-V percentage by 20% achieved similar radiation dose reduction and similar image quality .

目的 比较降低调节管电压与升高自适应迭代重组（adaptive statistical iterative reconstruction， ASIR）-V 迭代率对降低婴幼儿腹部增强 CT 扫描辐射剂量的影响。方法 回顾性分析 20 例行腹部增强 CT 检查的婴幼儿患者影像资料，扫描条件为 80 kVp，ASIR-V 40%（常规组）。另前瞻性收集年龄、性别及体 重匹配的婴幼儿患者 40 例，分为降低管电压组（扫描条件为 70 kVp，ASIR-V 40%）和升高迭代率组（扫描 条件为 80 kVp，ASIR-V 60%）。记录并计算每例患者的单期 CT 容积剂量指数（CT dose index，CTDI）、剂 量长度乘积（dose length product，DLP）、体型特异性剂量评估值（size-specific dose estimate，SSDE）及有 效剂量（effective dose，ED）。并由 2 名放射医师采用 5 分法对所有图像质量进行主观评分。采用组内相关 系数（ICC）评价 2 名医师图像质量评分的一致性 ；采用方差分析比较 CTDI、DLP、SSDE、ED 和主观评 分在 3 组间的差异，两两比较采用 Bonferroni 法。结果 性别、年龄和体重在 3 组间的差异无统计学意义 （P ＞ 0.05）。常规组、降低管电压组、升高迭代率组的 CTDI 分别为（0.51±0.06）mGy、（0.34±0.03）mGy、 （0.31±0.04）mGy，DLP 分别为（8.94±1.40）mGy-cm、（5.85±0.72）mGy-cm、（5.53±0.75）mGy-cm，SSED 分别为（1.15±0.12）mGy、（0.76±0.06）mGy、（0.68±0.07）mGy，ED 分别为（0.35±0.08）mSv、（0.26± 0.05）mSv、（0.21±0.03）mSv，图像质量评分分别为（4.26±0.30）分、（3.74±0.28）分、（3.50±0.53）分。 各剂量指标及图像质量评分在 3 组间的差异均有统计学意义（P ＜ 0.001）。其中降低管电压组与升高迭代率 组的辐射剂量、图像质量评分均明显低于常规组（P ＜ 0.001），但图像质量评分均能满足诊断需求（≥ 3 分）。 降低管电压组和升高迭代率组的辐射剂量、图像质量评分均无统计学差异（P ＞ 0.05）。 结论 婴幼儿腹部 增强 CT 在常规采用 80 kVp，ASIR-V 40% 的基础上，管电压降低 10 kVp 与 ASIR-V 迭代率增加 20% 辐射 剂量减低相似，且能获得同等水平图像质量。