锥束CT灌注成像方法的可行性研究

Feasibility study of cone-beam CT perfusion imaging methods

为研究图像引导放疗(IGRT)中锥形束CT(CBCT)在低速单周环扫条件下进行灌注成像的可行性,首先利用大白兔动态对比增强断层图像(DCE-CT),通过计算机仿真技术模拟CBCT投影数据;然后建立各体素的时间密度变化模型,利用所获投影数据集,计算出各体素的时间密度曲线(TDC);最后通过去卷积模型求解出组织灌注参数并伪彩色处理。对比仿真获得的投影数据模拟对应体素的时间密度曲线与原始DCE-CT获得的对应体素的TDC,得到的两组TDC平均相关系数达到0.87,呈现出较高的吻合度;实验所得灌注参数及灌注图显示:肿瘤区域与正常组织区域的灌注参数值之间具有统计学意义上的显著差异。实验结果获得了较为准确的组织灌注值,证明图像引导放疗中集成在直线加速器上的CBCT在低速单周环扫条件下进行灌注成像是可行的。

The feasibility of Cone Beam CT（ CBCT） perfusion imaging under the condition of low speed and single ring for Image Guided Radiation Therapy（ IGRT） was studied. Firstly,Dynamic Contrast-Enhanced CT（ DCE-CT） images of rabbits,by means of computer simulation technology,were used to simulate CBCT projection data; then the change of time density of each voxel was modeled to calculate Time Density Curve（ TDC） of each voxel based on the projection data; finally tissue perfusion parameters were solved by deconvolution model and processed by pseudo-color. Comparing the TDC from projection data in simulation system with the TDC at the same pixel from the original DCE-CT data,average correlation coefficient is 0. 87,indicating high similarity. The experiments of perfusion parameters and perfusion maps show that perfusion parameters have a statistically significant difference between the sense of regional tumor and normal tissue regions. The results obtained more accurate tissue perfusion value,prove CBCT integrated linac perfusion imaging under the condition of low speed and single ring for image-guided radiotherapy is feasible.