128层螺旋CT肺动脉低管电压成像的临床可行性研究

目的 探讨80 kV低管电压对128层螺旋CT肺动脉成像（CTPA）图像质量及辐射剂量的影响。方法 对临床怀疑肺栓塞患者60例行128层螺旋CT肺动脉成像检查，并采用随机数字表法分为低管电压80 kV组和常规管电压120 kV组各30例，两组均开启自动管电流调制技术。记录两组的CT容积剂量指数（CTDI_vol）、剂量长度乘积（DLP），计算有效剂量（E）值；测量图像背景噪声（BN）、肺动脉强化CT值（SI），计算信噪比（SNR）、对比噪声比（CNR）。比较两组的有效剂量E、SNR、CNR以及图像质量。结果 80 kV组的E为（0.99±0.27）mSv，显著低于120 kV组的（3.02±0.87）mSv（t=12.281，P<0.05）。80 kV组SI、BN均显著高于120 kV组（t=-3.377、-5.855，P<0.05），SNR、CNR和图像质量评分差异均无统计学意义（P>0.05）。结论 与常规管电压120 kV扫描方案相比，采用低管电压80 kV，结合自动管电流调制技术，可以在保证图像质量的同时，有效降低辐射剂量，在多层螺旋CT肺动脉成像中具有较高的临床应用价值。

The feasibility study of 80 kV in 128-slice MSCT pulmonary angiography

Objective To investigate the influence of 80 kV on dose reduction and image quality in 128-slice CT pulmonary angiography (CTPA) compared with the conventional 120 kV. Methods Sixty patients suspected of pulmonary embolism (PE) who underwent CTPA were randomly divided into 80 kV and 120 kV groups by random digits table method. All the patients underwent CTPA with automatic tube current modulation. The values of volume CT dose index (CTDI_vol), dose length product (DLP) were recorded and effective dose (E) was calculated. The attenuation was measured in central and peripheral pulmonary arteries as well as background noise (BN), then signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. The radiation exposure, pulmonary arterial enhancement, background noise, SNR, CNR and scores of image quality by a 5-point scale were compared between two groups. Results E value was significantly lower at 80 kV [(0.99±0.27)mSv] compared with 120 kV [(3.02±0.87) mSv, t=12.281, P<0.05].The mean attenuation value of pulmonary arteries as well as BN in 80 kV group were significantly higher than in 120 kV group (P<0.05). SNR and CNR did not differ significantly between two groups. No significant difference was detected on scores of image quality(P>0.05). Conclusions The application of 80 kV protocol combined with automatic tube current modulation scanning in 128-slice MSCT pulmonary angiography could significantly reduce radiation dose compared with the conventional 120 kV protocol without deterioration in diagnostic image quality.