采用体模评价DynaCT成像质量和辐射剂量

目的：对C型臂CT（DynaCT）头部扫描成像质量和辐射剂量进行综合分析,并比较多排螺旋CT（MSCT）和DynaCT成像质量和所致患者辐射剂量差异。方法：采用模拟人体体模测量2种成像所致患者的有效剂量,采用CT图像质量控制体模测量2种成像的高对比分辨率和低对比分辨率。DynaCT成像采用自动曝光控制扫描体模,多排螺旋CT采用临床常规扫描条件进行图像采集。结果：DynaCT头部检查有效剂量为1.10mSv,多排螺旋CT头部扫描有效剂量为2.07mSv。2种成像模式头部扫描所致器官剂量存在显著性差异（P〈0.05）。DynaCT和MSCT成像目测高对比分辨率均为12lp/cm;对于DynaCT,当对比度为0.3%时最小可识别物体直径为6mm,而对于MSCT为4mm。结论：对于头部检查DynaCT成像所致患者有效剂量低于MSCT。采用DynaCT成像可以在保证图像质量的同时降低辐射剂量。

Study of Image Quality and Radiation Dose of DynaCT on Anthropomorphic Phantom

Objective To assess the dose and image quality using a C-ann CT （DynaCT） system and compare the difference of imagequality and radiation dose between DynaCT and Multi slice CT （MSCT）. Methods Effective doses were measured from an anthropomorphic phantom with embedded thermoluminescence dosimeters （TLDs） .For DynaCT, automatic exposure control （AEC） and high-quality （20 s rotation time） scans were used. For MSCT, scanning protocols for head were examined with conventional exposure conditions. Catphan phantom（Phantom Lab, USA） was used to evaluate the image quality for DynaCT and MSCT. Results For DynaCT, the effective doses from head scanning were 1.10 mSv; for MSCT, the ef- fective doses from head scanning were 2.07 mSv, and there was a significant difference of organ dose between DynaCT and MSCT（P〈0.05）. The visual spatial resolution of DynaCT and MSCT was achieved with 12 lp/cm and a 6 mm low contrast object at 0.3% contrast level was recognized for DynaCT and 4 mm for MSCT. Conclusion The phantom study shows the effective dose from DynaCT is significantly lower than MSCT. DynaCT scans can be used to reduce radiation dose of patients while keeping image quality.[Chinese Medical Equipment Journal,2009,30（9） ：68-69]