应用低管电压技术降低下肢多层螺旋CT静脉成像辐射剂量的研究

［摘要］ 〖HTH〗目的〖HTSS〗〖KG*2〗探讨应用低管电压扫描技术降低下肢多层螺旋CT静脉成像辐射剂量的可行性及对CT图像质量的影响。 〖HTH〗方法〖HTSS〗〖KG*2〗前瞻性连续选择疑似下肢静脉疾病患者60例，采用双管双流法下肢CT静脉成像，随机分为低管电压组和对照组，每组30例。低管电压组CT扫描参数为80 kV、350 mAs、对比剂流速1.2 mL/s，对照组CT扫描参数为120 kV、190 mAs、对比剂流速2.5 mL/s。统计2组图像的对比噪声比（contrast to noise ratio，CNR）、信号噪声比（single-to-noise ratio,SNR）及辐射长度乘积(dose length product，DLP)，由2名资深影像学医师以5分制对图像质量进行主观评价。 〖HTH〗结果〖HTSS〗〖KG*2〗低管电压组DLP、有效剂量和对比剂碘海醇均明显低于对照组(P＜0.05)。2组图像CNR、SNR、主观评分差异均无统计学意义(P＞0.05)。 〖HTH〗结论〖HTSS〗〖KG*2〗低管电压下肢CT静脉成像扫描技术，在图像质量满足诊断要求的同时，可明显降低辐射剂量及碘对比剂剂量。

Radiation dose reduction at multi-slice spiral CT venography of lower limb with a low-tube voltage technique

［Abstract］Objective〖HTSS〗To investigate the effects oflow-tube-voltage computed tomography(CT) venography of lower extremity on image quality and the radiation dose. 〖HTH〗〖WTHZ〗Methods〖HTSS〗Sixty patients suspected with venous diseases of lower extremity were randomly divided into low tube voltage group and control group, 30 cases in each group, All patients underwent lower extremity CT venography on a 64-detector CT scanner. Parameters for CT venography were as follows: 80 kV and 350 mAs in low tube voltage group, and 120 kV and 190 mAs in control group. Contrast-to-noise ratio(CNR) and single-to-noise ratio(SNR) of imaging, dose length product(DLP) and effective dose were statistical analyzed with the 2-tailed independent t test or the Mann-Whitney U test. The image quality were evaluated by two senior doctors using 5 mark system. 〖HTH〗〖WTHZ〗Results〖HTSS〗DLP,effective dose and dose of contrast material were significantly lower under low tube voltage group than control group(P＜0.05). The CNR and SNR of low tube voltage group and control group were no statistical difference between two groups(P＞0.05). The subjective scores of image quality between two groups were not statistically significant(P＞0.05). 〖HTH〗〖WTHZ〗Conclusion〖HTSS〗CT venography with a low-tubevoltage technique allows reducing the radiation dose and the amount ofcontrast material without image quality degradation.