双源CT大螺距扫描模式下70 kV管电压结合迭代算法用于CT造影检查对图像质量及辐射剂量的影响

Influence of 70 kV tube voltage combined with iterative algorithm on image quality and radiation dose in CCTA examination under dual source CT large pitch scanning mode

目的分析双源CT大螺距扫描模式下70 kV管电压结合迭代算法用于CCTA检查对图像质量及辐射剂量的影响。方法2019年1月至2020年2月我院收治的行CCTA检查、体重指数(BMI)≤25 kg/m^(2)的患者76例随机分为对照组和观察组,各38例。对照组扫描方案为自适应前瞻性心电门控触发序列,参考管电压120 kV,对比剂注射流率为5.0 ml/s,容量为1.0 ml/kg;图像采集采用迭代重建算法(SAFIRE)3级重建。观察组扫描方案为前瞻性心电门控大螺距螺旋扫描模式,固定管电压70 kV,对比剂注射流率为4.0 ml/s,容量为0.8 ml/s;图像采集采用滤波反投影法(FBP)及SAFIRE 1~5等级重建。统计观察组扫描图像质量,比较2组图像冠状动脉节段各指标、图像质量及辐射剂量。结果观察组图像噪声比较,FBP、SAFIRE 1高于SAFIRE 2、3、4、5(P<0.05),SAFIRE 2高于SAFIRE 3、4、5(P<0.05),SAFIRE 3高于SAFIRE 4、5(P<0.05),SAFIRE 4高于SAFIRE 5(P<0.05);SNR、CNR比较,FBP、SAFIRE 1低于SAFIRE 2、3、4、5(P<0.05),SAFIRE 2低于SAFIRE 3、4、5(P<0.05),SAFIRE 3低于SAFIRE 4、5(P<0.05),SAFIRE 4低于SAFIRE 5(P<0.05);图像质量比较,FBP、SAFIRE 1、5低于SAFIRE 2、3、4(P<0.05)。观察组右冠状动脉(RCA)开口CT值,左冠状动脉主干(LM)开口CT值、信号噪声比(SNR),左前降支(LAD)开口CT值、SNR、对比度噪声比(CNR)及左回旋支动脉(LCX)开口CT值、CNR均高于对照组(P<0.05)。观察组CT剂量指数(CTDI)、剂量长度乘积(DLP)及有效剂量(ED)均低于对照组(P<0.05)。结论双源CT大螺距扫描模式下70 kV管电压结合迭代算法用于体重指数(BMI)≤25 kg/m^(2)患者的CCTA检查,可有效提高图片质量,同时降低辐射剂量。

Objective To analyze the influence of 70 kV tube voltage combined with iterative algorithm on image quality and radiation dose in CCTA examination under large pitch scanning mode of dual source CT.Methods From January 2019 to February 2020,76 patients with CCTA examination and BMI≤25 kg/m^(2) were selected as the research objects,and were divided into the control group(38 cases)and the observation group(38 cases)by random number table method.The scanning scheme of control group was adaptive prospective ECG trigger sequence,with reference tube voltage of 120 kV,contrast injection flow rate of 5.0 ml/s and volume of 1.0 ml/kg.SAFIRE 3 level reconstruction was used for image acquisition.The scanning scheme of observation group was prospective ECG-gated spiral scanning mode with fixed tube voltage of 70 kV,contrast injection flow rate of 4.0 ml/s and volume of 0.8 ml/s;FBP and SAFIRE 1~5 levels were used for image acquisition.The scanning image quality of observation group was counted,and the indexes of coronary artery segment,image quality and radiation dose were compared between the two groups.Results In the image noise of observation group,FBP and SAFIRE 1 were higher than SAFIRE 2,3,4 and 5(P<0.05),SAFIRE 2 was higher than SAFIRE 3,4 and 5(P<0.05),SAFIRE 3 was higher than SAFIRE 4 and 5(P<0.05),and SAFIRE 4 was higher than safire 5(P<0.05).For SNR and CNR,FBP and SAFIRE 1 were lower than SAFIRE 2,3,4 and 5(P<0.05),SAFIRE 2 was lower than SAFIRE 3,4 and 5(P<0.05),SAFIRE 3 was lower than SAFIRE 4 and 5(P<0.05),and SAFIRE 4 was lower than safire 5(P<0.05).As for the image quality,FBP,SAFIRE 1 and 5 were lower than SAFIRE 2,3 and 4(P<0.05).In the observation group,SAFIRE 1~5 image nois decreased in turn,CNR and SNR increased in turn,and SAFIRE 3 image quality score was the highest.CT value of RCA,LM,LAD,SNR,CNR,LCX and CNR in observation group were higher than those in control group(P<0.05).CTDI,DLP and ED in the control group were higher than the observation group(P<0.05).Conclusion The application of 70 kV tube voltage combined with iterative algorithm in CCTA examination of patients with BMI≤25 kg/m^(2) in dual source CT scan mode could effectively improve picture quality and reduce radiation dose.