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目的建立计算机仿真系统,研究基于投影数据的锥形束CT(cone-beamCT,CBCT)灌注成像的方法,探索实现在线功能图像引导的放疗(biologic image guided radiation therapy,BIGRT)的可能性。方法通过计算机仿真技术,利用大白兔动态增强CT(dynamic contrast enhancedCT,DCE-CT)图像数据集模拟获取CBCT动态增强扫描的投影数据集;通过对扫描对象各体素的时间密度变化进行数学建模,基于获得的投影数据集,经最优化拟合求得各体素模型的参数,获取CBCT动态增强扫描下各体素的时间密度曲线(time-density curve,TDC)。结果对比仿真系统获得的锥形束CT下各体素的TDC和原DCE-CT获得的对应体素的TDC,发现在对比剂首次通过时的上升沿有较好吻合,在循环进入平衡后差异较大。结论基于投影数据可实现CBCT灌注成像,获得较为准确的血流灌注值,证明了利用集成在直线加速器上的CBCT实现在线的功能成像是可能的。
Objective To establish a computer simulation system to study cone-beam CT (CBCT) perfusion imaging based on projection data and to explore the possibility of realizing online functional image guided radiation therapy (BIGRT). Methods The CBCT dynamic contrast-enhanced projection data set was acquired by computer simulation of dynamic contrast-enhanced CT (DCE-CT) image data sets. By mathematically modeling the temporal density changes of each voxel, Based on the obtained projection datasets, the parameters of each voxel model were obtained by optimization fitting, and the time-density curve (TDC) of each voxel under CBCT dynamic enhanced scanning was obtained. Results Compared with the TDC of each voxel obtained from the cone beam CT and the corresponding TDC of the voxel obtained from the original DCE-CT, it was found that there was a good coincidence at the rising edge of the first pass of the contrast agent. After the cycle entered equilibrium Larger. Conclusion CBCT perfusion imaging can be achieved based on the projection data to obtain more accurate perfusion values, which proves that it is possible to perform online functional imaging using CBCT integrated in a linear accelerator.