摘要
目的本文探讨了应用自动管电流调节技术(Automatic Tube Medical University,ATCM)行胸部CT扫描时,管电压的变化对图像质量及辐射剂量的影响。方法应用GE Optima CT680 CT机采用ATCM技术对胸部仿真模体行CT扫描。共进行3组扫描,其中A组管电压为80 k Vp,B组管电压为100 k Vp,C组管电压为120 k Vp,各组分别预设5个噪声指数(Noise Index,NI)级别(10、15、20、25和30)扫描体模。记录每组图像的容积CT剂量指数(Volumetric CT Dose Index,CTDIvol)和剂量长度乘积(Dose-Length Product,DLP)。测量并比较图像的客观噪声(Standard Deviation,SD),由两名有经验的放射科医生采用双盲法对磨玻璃密度结节(Ground Glass Nodules,GGN)进行主观评分。结果研究结果显示,除NI为10以外,在其他相同NI时,图像客观噪声无统计学差异。NI在15、20、25和30时,A组与C组比较时,DLP分别增加21.96,16.25、9.18和6.37 m Gy·cm。B组与C组比较时,DLP分别增加14.05、8.50、5.17和3.65 m Gy·cm。相同预设NI时不同管电压下对GGN主观评分无明显统计学差异,且两名观察者间的一致性中等或良好。结论应用ATCM技术,相同预设NI下管电压的变化对图像质量不会产生明显影响。患者的辐射剂量随着扫描管电压的增高而降低。
Objective The purpose of this study was to evaluate the consequences of different tube voltages on radiation dose and image quality with an automatic tube current modulation （ATCM） system on CT scanning of chest. Methods The chest phantom was scanned on GE Optima CT 680 scanner. Images were obtained at varying tube voltage （80, 100, and 120 kVp） and varying noise index （10, 15, 20, 25 and 30） with an ATCM system. Volumetric CT dose index （CTDIvo~） and dose-length product （DLP） was recorded in the CT scanner. The objective noise of images were measured. Two experienced radiologists blinded to the CT parameters were invited to assess the identification of ground glass nodules （GGN）. Results There was no significant difference in objective noise at the same NI level besides NI of 10. The DLP of scanning at tube voltage of 80 kVp increased by 21.96, 16.25, 9.18, 6.37 mGy.cm compared with that of 120 kVp at the NI of 15, 20, 25 and 30. The DLP increased by 14.05, 8.50, 5.17 and 3.65 mGy.cm respectively at tube voltage of 100 kVp compared with that of 120 kVp at the NI of 15, 20, 25 and 30. There is no significant difference in the assessment of GGN among the varying tube voltage settings at the same NI level. Kappa value of the identification of the GGNs was substantial or almost perfect. Conclusion The image quality is not significantly affected by the different tube voltages based on ATCM system. The radiation dose of patients is decreased with the increasing of tube voltage.
出处
《中国医疗设备》
2018年第2期69-72,共4页
China Medical Devices
作者简介
通讯作者：钟朝辉，副主任技师，主要研究方向为CT影像技术。通讯作者邮箱：laijinyuxuan12@sina．com
