螺旋断层放射治疗机MVCT影像质量的测量分析

目的分析螺旋断层放射治疗MVCT的影像质量。方法用CatPhan600体模测量测试MVCT值均匀性和线性、影像噪声、空间分辨率,低对比度和几何精确性,分析螺距对图像质量的影响,并对影响图像质量的因素进行讨论。结果MVCT影像CT值成线性分布,但是和参考CT值有一定的差别,均匀性较好,空间分辨率为4Lp/cm,低对比度分辨率差于诊断CT和锥形束CT,但可以满足图像引导的要求,几何准确性较好,图像无明显形变发生。结论MVCT影像质量不如常规诊断CT,但图像质量可以满足临床治疗中的影像引导的要求。

Analysis of Megavoltage Computed Tomography Imaging on a Helical Tomotherapy Unit

Objective To evaluate the image quality of megavoltage computed Tomography imaging.Methods The HU uniformity and linearity,image noise,spatial resolution,low contrast resolution and spatial linearity in MVCT mode were evaluated with Catphan 600 phantom,and the factor of pitch was also evaluated.Influencing factors of image quality were also discussed.Results The MVCT values depended linearly on the physical density of the sample.The MVCT values uniformity was good.The spatial resolution was 4lp/cm.The use of an MV Beam for imaging results in the loss of low contrast resolution,but it is sufficient for pretreatment image guidance.The geometric accuracy was good.Conclusions The image quality of MVCT is less than that of KVCT,but is good enough for IGRT.