螺旋CT自动管电流技术在胸部检查中的辐射防护价值

目的探讨螺旋CT自动管电流技术在胸部检查中辐射防护价值。方法实验组和对照组各30例，分别采用CT自动管电流（噪声指数=10．00）和固定管电流（200mA）技术进行胸部检查，对所获图像噪声特性、细节显示程度及CT设备本身剂量信息显示结果进行比较。结果实验组和对照组主动脉弓上层面、气管隆突和横膈上层面肺野内CT值差异不具显著性（P=0．136，0．289，0．176），主动脉弓上层面图像背景标准差差异无统计学意义（P=0．121），但气管隆突和横膈上层面图像背景标准差差异有统计学意义（P=0．001，0．000），实验组大于对照组。实验组和对照组肺内细小血管、细支气管、叶间裂等细微结构显示程度以及病变形态特征显示无差别。两组图像主动脉弓上层面均可见线状假影，但实验组有假影的层面多，图像噪声颗粒比对照组明显。实验组CTDIvol和剂量长度乘积（DLP）约为对照组的1／3。结论正确使用CT自动管电流技术可以在确保图像质量同时降低受检者所受辐射剂量。

Importance of automatic tube current technology with mutli-detector CT in chest test

Objective To explore the importance of automatic tube current technology of multi-detector CT in chest test. Methods Each group of study and control include 30 cases. The technology of auto tube current(noise index=10.00) and fixed tube current(200 mA) were performed separately. Comparision with image noisiness and detail to show and information of dose was made. Results There is no significant difference(P=0.136,0.289,0.176) between both groups in CT value in the supra-aortic arch,tracheal prominence and supra-diaphragmatic level respectively with no significant difference (P=0.121) of background SD in supra-aortic arch level.There is significant difference(P=0.001,0.000) of background SD in tracheal prominence and supra-diaphragmatic level respectively. There is no significant difference between study and control groups in demonstration of grade and morphology in pulmonary micro-vessels,bronchiole and interlobar fissure etc.Linear artifact was found in both study and control group in supra-aortic arch level,but more slices with artifact and more noise granule in study group. CTDI_ vol and DLP were about 1/3 of control group. Conclusions Utilization of CT auto tube current can ensure the image quality and reduce the dose of patients.