应用Z-DOM技术降低MSCT腹部多期检查辐射剂量

目的:通过对比分析采用不同管电流调节技术所得的图像质量和放射剂量,探讨在MSCT肝脏多期检查中以较低的放射剂量获得较高图像质量的可行性。方法:按照统一的纳入和排除标准,随机选取68例患者行MSCT肝脏多期检查。将患者分为A、B两组,每组34例。A组采用Z-轴自动毫安调节技术(Z-DOM),B组采用常规的固定mAs技术(250mAs),2组其余扫描参数相同。由两位有经验的CT诊断医师以双盲法分别对A、B组图像进行质量评分(噪声评分和诊断可接受性评分),记录并比较2组的剂量长度乘积(DLP)和有效剂量(ED)。对两组图像质量评分、DLP及ED值的差异进行统计学分析。结果:两组各解剖层面的图像质量评分差异无统计学意义(U值492.0～575.5,P>0.05);A、B组的平均DLP和ED值分别为1005.1mGy/cm和15.1mSv及1132.3mGy/cm和17.0mSv。A组的DLP、ED明显低于B组(降低约11.2%),两组差异有统计学意义(P<0.001)。结论:在MSCT肝脏多期检查中使用Z轴自动毫安调节技术可以有效地减少受检者的辐射剂量,同时可以获得高质量的诊断图像。

Preliminary Study of Radiation Reduction of Abdomen by Applying Z-axis Automatic Tube Current Modulation Technique in Multi-slice CT Scanning

Objective:To evaluate the influence of different tube current modulation techniques of multi-slice CT on image quality and radiation dosage,in order to look for a feasible low radiation dosage yet high image quality technique in abdomen CT scanning.Methods:68 patients were randomly selected to undertake multi-phase dynamic CT scanning of liver.These patients were divided into two groups with 34 patients for each.Patients in group A undertook Z-axis automatic tube current modulation (Z-DOM) technique,and routine fixed mAs protocol (250mAs) was used in group B.The other scanning parameters were similar for the two groups.Two experienced radiologists quantitatively evaluated the image quality with double-blind method.The dosage length product (DLP) and effective dosage (ED) of these 2 groups were recorded and compared.The score of image quality,DLP and ED values were analyzed to find out any statistical differences existed.Results:There were no statistical difference in image quality scores of the anatomy planes of the two groups (U value:492.0~575.5,P>0.05).The mean DLP and ED values of the two groups were 1005.1mGy/cm,15.1mSv and 1132.3mGy/cm,17.0mSv respectively.DLP and ED of group A were markedly lower than that of group B (reduce for about 11.2%) and significant statistical differences were existed (P<0.001).Conclusion:The overall dosage taken by patients could be effectively reduced and high quality images for clinical diagnosis could be obtained by using Z-DOM technique in multi-phase dynamic MSCT scanning for liver examination.