影像引导放疗中常用CT设备影像质量的比较分析

Comparison Study of Image Qualities for Commonly Used CT Scanners in Image-guided Radiotherapy

目的:分析影像引导放疗中常用的模拟定位螺旋CT(MSCT)、加速器机载锥形束CT(CBCT)和螺旋断层治疗机MV螺旋CT(MVCT)的影像质量。方法:CatPhan600模体测量三种成像设备的CT值均匀性和线性、空间分辨率、低对比度分辨率、3D影像的几何准确性和金属伪影大小。结果:MSCT、CBCT和MVCT的CT值与物质密度均呈线性关系;均匀模体中的CT均匀性分别为1.07%,1.40%,39.81%;空间分辨率分别为8 lp/cm,7 lp/cm,4 lp/cm;MSCT可显示低对比度为1%的3 mm圆孔,CBCT只能略微分辨圆孔,而MVCT则无法显示圆孔,几何准确性均良好;MVCT的金属伪影较小。结论:CBCT和MVCT的成像质量均不如MSCT,但能满足患者治疗体位验证和监测的需要。

Objective: To evaluate the image qualities of Multi-slice CT(MSCT),Cone-beam CT(CBCT),Megavoltage CT(MVCT) commonly used in image-guided radiotherapy.Methods: The CT uniformity and linearity,spatial resolution,low contrast resolution and geometrical accuracy,metal artifacts in three CT modes were evaluated with Catphan600 phantom.Results: CT values depended linearly on the physical densities of the samples for all three CT modes,but maximum noise was found in MVCT.The CT uniformity for MSCT,CBCT,and MVCT wa...