kV Assist 2.0联合自动管电流调制在256排CT腹盆部检查中的应用研究

Application of kV Assist 2.0 combined with automatic tube current modulation in abdominal pelvic examination with 256-slice CT

目的:探讨新一代智能最佳管电压技术(kV Assist 2.0)联合自动管电流调制在CT腹盆部扫描中的应用价值。方法:前瞻性搜集474例行腹盆部CT平扫检查的患者,使用简单随机方法分为固定噪声指数(NI)组164例、自动NI组156例和对照组154例,3组均使用自动毫安调制技术,固定NI组和自动NI组在扫描的同时记录患者身体径线(前后径+左右径),将得到的薄层图像传至工作站进行分析,测量、计算得到肝脏、脾脏、臀大肌的SNR、CNR及表征辐射剂量的CT剂量指数(CTDI)、剂量长度乘积(DLP)、有效剂量(ED),对图像质量和辐射剂量行单因素方差分析。结果:3组噪声水平差异无统计学意义(F=0.173,P=0.841);3组肝脏SNR、肝脏CNR、脾脏SNR、肌肉SNR、肌肉CNR差异均无统计学意义(均P>0.05);脾脏CNR差异有统计学意义(F=3.03,P=0.049),事后比较,仅固定NI组与对照组差异有统计学意义(P=0.014)。3组间主观评分差异无统计学意义(P>0.05)。3组CTDI差异有统计学意义(F=12.306,P<0.001);事后比较显示,对照组与固定NI组、自动NI组差异均有统计学意义(均P<0.001)。3组的DLP和ED差异均有统计学意义(均P<0.05),事后比较,对照组与固定NI组、自动NI组差异均有统计学意义(P=0.003,0.008)。固定NI组的ED相较于对照组降低12.4%,而自动NI组的ED相较于对照组仅降低9.0%。结论:固定NI的扫描策略在图像质量稍有改善的基础上,能明显降低辐射剂量,在kV Assist 2.0的腹盆部扫描中更有价值。

Objective:To explore the application value of the new generation intelligent optimal tube voltage technology(kV Assist 2.0)combined with automatic tube current modulation in abdominal pelvic CT examination.Methods:474 patients who underwent plain abdominal pelvic CT scan were prospectively collected and randomly divided into three groups,including 154 cases in the control group,164 cases in the fixed NI group and 156 cases in the automatic NI group.All scanning used automatic milliampere modulation technology.The size of patients(AP+LAT)was recorded while scanning in fixed NI group and automatic NI group.The thin-layer images were transmitted to the workstation for analysis.The SNR and CNR of liver,spleen and gluteus maximus and CTDI,DLP,ED values were measured and calculated.The image quality and radiation dose were analyzed by one-way ANOVA.Results:The noise,liver SNR,liver CNR,spleen SNR,muscle SNR and muscle CNR of the three groups had no statistical differences(all P>0.05),while the spleen CNR of the three groups had a statistical difference(F=3.03,P=0.049),and the post-hoc comparison showed that there was only a statistical difference of the spleen CNR between the fixed NI group and the control group(P=0.014).The subjective score had no significant difference among the three groups(P<0.05).The CTDI of the three groups had the statistical difference(F=12.306,P<0.001),and the post-hoc comparison showed that there were statistical differences between the control group and the fixed NI group and between the control group and the automatic NI group(both P<0.001).DLP and ED of the three groups had statistical differences(both P<0.05),and the post-hoc comparison showed that there were statistical differences between the control group and the fixed NI group and between the control group and the automatic NI group(P=0.003,0.008).The ED in the fixed NI group decreased by 12.4%compared with the control group,while the ED in the automatic NI group decreased by only 9.0%compared with the control group.Conclusions:The scanning strategy of fixed NI can significantly reduce the radiation dose on the basis of slightly improved image quality,and is more valuable in the abdominal pelvic CT scanning of kV Assist 2.0.