ASiR算法结合自动管电流调制技术在胸部低剂量CT中的应用研究

摘要

Objective:To study the application of the adaptive statistical iterative reconstruction (ASiR) combined with automatic tube current modulation scanning in chest CT scan on GE Discovery CTHD 750 and to evaluate the feasiblity of low dose scan in chest CT. Methods: 100 continual patients underwent chest CT scan on GE Discovery CTHD 750 were randomly divided into two groups (A and B, each containing 50 patients). Automatic tube current modulation scanning was performed, with noise index 15 HU in group A and 25 HU in group B. Images were reconstructed with different settings of ASiR(0~100%). CT dose index volumes (CTDI vol). Dose length product (DLP) were recorded, and effective dose (ED) was calculated. The imaging quality was evaluated by three radiologists blindly and independently with a 5-point scoring method. Results:CTDl vol and ED were 4. 22 mGy and 2. 51 mSv in group A, while 1. 51 mGy and 0. 89 mSv in group B. Which decreased by 64. 22% and 64. 54% respectively. Image quality in both groups met the diagnostic requirements. Conclusion: Radiation dose can be significantly decreased with image quality maintained using automatic tube current modulation scanning combined with ASiR reconstruction in chest CT scan on GE Discovery CTHD 750.%目的:研究自适应性统计迭代重建(ASiR)算法结合自动管电流调制技术在MSCT( GE Discovery CTHD 750HD)胸部扫描中的应用,探讨胸部低剂量扫描的可行性.方法:将100名拟行宝石CT胸部平扫的患者随机分为A、B两组,每组50名.使用自动管电流调制技术扫描,A组预设噪声指数(NI)为15HU,B组预设NI为25HU,并采用不同权重的ASiR进行图像重建.记录两组患者CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)并计算有效剂量(ED).三位放射科医师采用盲法对图像质量进行评估(5分制).结果:A组CTDIvo1为4.22 mGy,ED为2.51mSv,B组CTDIvol为1.51mGy,ED为0.89mSv,分别比A组降低了64.22％和64.54％.A、B两组的图像质量均能满足临床诊断要求.结论:使用ASiR重建算法结合自动管电流调制技术进行宝石CT胸部扫描,可以大幅降低辐射剂量,同时保证图像质量.