图像域迭代重建算法对腹部CT平扫图像质量和辐射剂量的影响

Effects of iterative reconstruction in image space on the quality of abdominal CT plain scan image and radiation dose

目的:探讨图像域迭代重建算法对腹部CT平扫图像质量及辐射剂量的影响。方法:以辽阳市中心医院2017年1月～2018年4月行腹部CT平扫的150例患者为研究对象,依据就诊先后顺序随机将其分为观察组与对照组,各75例。均行自动毫安控制技术扫描,管电压均为130 k V。观察组预设图像质量参考毫安秒150 mAs,行图像域迭代重建算法重建;对照组预设图像质量参考毫安秒250 m As,行滤波反投影重组。通过CT值、图像噪声SD、图像信噪比、对比噪声比评价两组图像客观质量,并行图像质量主观评价,记录两组CT剂量容积指数。结果:观察组肝脏、脾脏的图像噪声SD均显著低于对照组,图像信噪比均显著高于对照组,差异有统计学意义(P<0.05);CT值、对比噪声比、主观整体质量评分两组比较差异均无统计学意义(P>0.05);观察组CT剂量容积指数为(10.02±2.85)mGy,显著低于对照组的(15.68±4.36)mGy,差异有统计学意义(P<0.05)。结论:图像域迭代重建算法不仅能保证腹部CT平扫图像质量,而且能有效减少辐射剂量。

Objective To explore the effects of iterative reconstruction in image space(IRIS)on the quality of abdominal CT plain scan image and radiation dose.Methods A total of 150 patients who underwent abdominal CT plain scan in the Central Hospital of Liaoyang City between January 2017 and April 2018 were selected as subjects.The patients were randomly divided into observation group and control group,with 75 cases in each group.The scans were performed by automatic milliampere control technique,with a tube voltage of 130 kV.In observation group,the preset image quality reference milliampere second was 150 mAs,and IRIS was performed;in control group,the preset image quality reference milliampere second was 250 mAs,and filtered back projection(FBP)reconstruction was performed.The quality of two groups of images was objectively evaluated with CT value,image noise SD,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR).Meanwhile,the subjective evaluation of image quality was performed.The volume CT dose indexes in both groups were recorded.Results The image noise SD of the liver and spleen in observation group was significantly lower than that in control group,while the SNR was significantly higher than that in control group(P<0.05).No statistical differences were found in CT value,CNR and the subjective score of overall quality between the two groups(P>0.05).The volume CT dose index in observation group was(10.02±2.85)mGy,significantly lower than(15.68±4.36)mGy in control group(P<0.05).Conclusion IRIS can not only ensure the quality of CT plain scan images,but also effectively reduce the radiation dose.