自动毫安技术在腹部增强CT检查中可行性研究

Anto-mA Technique for Abdominal Enhanced CT Angiography: a feasibility study

目的:探讨腹部CT增强检查中使用自动毫安(ATCM)技术对降低患者辐射剂量的可行性。方法:搜集50例腹部疾病的患者行自纵隔上2 mm至髂嵴线水平CT容积扫描,每例常规3期(平扫期、动脉期、静脉期),随机分为固定毫安(FM)组和自动毫安(ATCM)技术组,FM组使用固定300 mA,ATCM组使用自动毫安技术,通过预实验改变噪声指数(NI)调节管电流,得出NI值为9.10 Hu时图像质量与辐射剂量匹配较佳;分别选择隔下腹主动脉、肝门静脉作为观察平面,对2种毫安技术的图像质量、图像噪声和辐射剂量均采用t检验方法进行统计学分析。结果:FM组的辐射剂量平均CTDIvol为23.68 mGy,平均DLP为597.22 mGy·cm;ATCM组的平均CTDIvol为6.44 mCy,平均DLP为154.226 mGy·cm,比FM组降低约74.2%。2组差异有统计学意义(CTDIvol、DLP的t值分别为45.100、112.57,P值均<0.05)。结论:在腹部增强CT检查中使用自动毫安控制技术,在保证图像质量的前提下,可以使患者所受辐射剂量降低约74.2%。

Objective To investigate the value of auto-mA technique for reducing radiation dose of abdominal enhanced CT angiography. Methods Fifty patients suspicious of abdominal disease underwent CT volume scanning arranged from 2 mm above the mediastinum to the iliae crest line level, and the scanning included three phases, that was, simple scan phase, arterial phase and venous phase. The patients were divided into two groups of fixed mA（FM） and auto mA（ATCM）, of which, the former employed the fixed 300 mA and the latter adopted auto-mA technique. Preliminary experiment was used to change the noise index（NI） to regulate the tube current. The image quality matched well with the radiation dose when NI was 9.10. With the subphrenic abdominal aorta and hepatic portal vein as the observation levels, t-test was used for the statistical analyses of the image quality, image noise and radiation dose by the two mA techniques, Results As for the radiation dose, FM group had its average CTDIvol as 23.68 mGy and average DLP as 597.22 mGy-cm, and ATCM group had its average CTDIvol as 6.44 mGy and average DLP as 154.226 mGy.cm. ATCM group had its values lower than those of FM group by 74.2%, and there was significant difference between them, with the values of t as 45.100 and 112.57 respectively and P〈0.05. Conclusion The application of auto-mA technique to abdominal enhanced CT angiography makes the radiation close lowered by 74.2%, with the image quality ensured.