应用Z-DOM技术降低MSCT腹部多期检查辐射剂量

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

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。

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. lmGy/cm, 15. 1roSy 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.