64排CT骨盆低剂量扫描技术的探讨

目的探讨不同管电流值对64排CT骨盆低剂量扫描图像质量的影响，获取较佳的低剂量扫描方案。方法随机选取50名志愿者进行64排CT骨盆扫描，随机分成5组，每组10名，管电流设定值分别为250mA、150mA、100mA、50mA和30mA，其他扫描参数不变。扫描时分别测量辐射剂量值，并对原始图像及重组图像进行评分。统计分析不同的管电流值扫描的辐射剂量和图像质量。结果管电流为250mA、150mA和100mA的骨盆图像中，软组织的图像质量评分无统计学差异，50mA和30mA的图像质量评分低于与250mA的图（P〈0.05）。不同管电流值的骨组织显示质量评分无统计学差异（P〉0．05）；本组实验得到骨盆64排CT低剂量扫描管电流的最低值是30mA，单纯将管电流由标准250mA降至低30mA时，患者所接受的平均辐射剂量由14．7mGy降至1．8mGy。结论不同管电流值对软组织图像显示质量的影响较骨组织明显，应根据要重点观察的组织来选择适当的扫描方案进行64排CT骨盆低剂量扫描。

The study of low-dose scanning technique with 64-row CT on pelvis

Objective To investigate the relationship between tube current and image quality of low dose scan with 64-row CT on pelvis, in order to get the better low dose scan planning. Methods Fifty volunteers were chosen and divided into 5 groups averagely to perform pelvis examination with 64-row CT. The different tube currents were set in each group, which were 250mA, 150mA, 100mA, 50mA and 30mA respectively. All of the other technical parameters remained same. The radiation doses were measured during the process of scan. The original images and the recomposed images were evaluated. The radiation dose and image quality were analyzed correlated with the different tube currents. Results For the image quality of the soft tissue, there was no statistics difference in groups when the tube currents were 250mA, 150mA and 100mA, but it lowered when the tube currents decreased to 50mA and 30mA （P〈0.05）. There was no statistics difference （P〉0.05） in the groups with different tube currents for the image quality of bone tissue. The lowest dose of 64-row CT scan on pelvis was 30mA. The mean radiation dose of 64-row CT scan on pelvis was reduced significantly from 14.8 mGy to 1.8 mGy when the tube current decreased from standard 250mA to 30mA. Contusion Tube current value affected the image quality on soft tissue more obviously than that on bone tissue. The proper lower dose 64-row CT scan on pelvis should be implemented based on the main structures to be observed.