A METHOD TO ESTIMATE MEAN POSITION, MOTION MAGNITUDE, MOTION CORRELATION, AND TRAJECTORY OF A TUMOR FROM CONE-BEAM CT PROJECTIONS FOR IMAGE-GUIDED RADIOTHERAPY
A METHOD TO ESTIMATE MEAN POSITION, MOTION MAGNITUDE, MOTION CORRELATION, AND TRAJECTORY OF A TUMOR FROM CONE-BEAM CT PROJECTIONS FOR IMAGE-GUIDED RADIOTHERAPY
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DOI：
10.1016/j.ijrobp.2008.07.037
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发表时间：
2008-12-01
影响因子：
7
通讯作者：
Keall, Paul J.
中科院分区：
文献类型：
--
作者：
Poulsen, Per Rugaard;Cho, Byungchul;Keall, Paul J.
目的：为了开发一种基于概率的方法，用于估计平均位置，运动幅度，和轨迹的肿瘤使用锥形束CT（CBCT）projections.Method and Materials：CBCT采集模拟超过80小时的患者测量的轨迹胸/腹部肿瘤和前列腺。将轨迹分成60秒的片段，通过将肿瘤位置投影到旋转成像仪上来模拟CBCT。假设所有投影上的肿瘤（替代物）可见。肿瘤位置的平均值和标准差以及沿三个轴的沿着运动相关性通过基于投影数据的最大似然估计来确定，假设高斯空间分布。沿成像器轴沿着的未知位置分量由其期望值近似，该期望值由高斯分布确定。将所得三维位置转换为患者坐标提供了估计的轨迹。结果：两种轨迹的估计平均位置的均方根误差为0.05 mm，轨迹的均方根误差为0.05 mm，平均位置的均方根误差为0.05 mm。
Purpose: To develop a probability-based method for estimating the mean position, motion magnitude, and trajectory of a tumor using cone-beam CT (CBCT) projections.Method and Materials: CBCT acquisition was simulated for more than 80 hours of patient-measured trajectories for thoracic/abdominal tumors and prostate. The trajectories were divided into 60-second segments for which CBCT was simulated by projecting the tumor position onto a rotating imager. Tumor (surrogate) visibility on all projections was assumed. The mean and standard deviation of the tumor position and motion correlation along the three axes were determined with maximum likelihood estimation based on the projection data, assuming a Gaussian spatial distribution. The unknown position component along the imager axis was approximated by its expectation value, determined by the Gaussian distribution. Transformation of the resulting three-dimensional position to patient coordinates provided the estimated trajectory. Two trajectories were experimentally investigated by CBCT acquisition of a phantom.Results: The root-mean-square error of the estimated mean position was 0.05 mm. The root-mean-square error of the trajectories was