Division of Radiation Oncology, City of Hope National Medical Center, Duarte, California, USA.
Int J Radiat Oncol Biol Phys. 2013 Mar 1;85(3):862-5. doi: 10.1016/j.ijrobp.2012.06.015. Epub 2012 Jul 24.
To compare Tomotherapy's megavoltage computed tomography bony anatomy autoregistration with the best achievable registration, assuming no deformation and perfect knowledge of planning target volume (PTV) location.
Distance-to-agreement (DTA) of the PTV was determined by applying a rigid-body shift to the PTV region of interest of the prostate from its reference position, assuming no deformations. Planning target volume region of interest of the prostate was extracted from the patient archives. The reference position was set by the 6 degrees of freedom (dof)-x, y, z, roll, pitch, and yaw-optimization results from the previous study at this institution. The DTA and the compensating parameters were calculated by the shift of the PTV from the reference 6-dof to the 4-dof-x, y, z, and roll-optimization. In this study, the effectiveness of Tomotherapy's 4-dof bony anatomy-based autoregistration was compared with the idealized 4-dof PTV contour-based optimization.
The maximum DTA (maxDTA) of the bony anatomy-based autoregistration was 3.2 ± 1.9 mm, with the maximum value of 8.0 mm. The maxDTA of the contour-based optimization was 1.8 ± 1.3 mm, with the maximum value of 5.7 mm. Comparison of Pearson correlation of the compensating parameters between the 2 4-dof optimization algorithms shows that there is a small but statistically significant correlation in y and z (0.236 and 0.300, respectively), whereas there is very weak correlation in x and roll (0.062 and 0.025, respectively).
We find that there is an average improvement of approximately 1 mm in terms of maxDTA on the PTV going from 4-dof bony anatomy-based autoregistration to the 4-dof contour-based optimization. Pearson correlation analysis of the 2 4-dof optimizations suggests that uncertainties due to deformation and inadequate resolution account for much of the compensating parameters, but pitch variation also makes a statistically significant contribution.
比较 Tomotherapy 兆伏级 CT 骨性解剖自动配准与最佳可实现的配准，假设无变形且完全了解计划靶区 (PTV) 的位置。
通过将前列腺的 PTV 感兴趣区从其参考位置施加刚体平移，确定 PTV 的距离一致性 (DTA)，假设无变形。从患者档案中提取前列腺的 PTV 感兴趣区。参考位置由本机构之前研究的 6 自由度 (dof)-x、y、z、滚转、俯仰和偏航优化结果设定。通过将 PTV 从参考 6 自由度平移到 4 自由度-x、y、z 和滚转优化，计算 PTV 从参考位置的 DTA 和补偿参数。在这项研究中，将 Tomotherapy 的 4 自由度骨性解剖自动配准的有效性与理想化的 4 自由度 PTV 轮廓优化进行了比较。
骨性解剖自动配准的最大 DTA (maxDTA) 为 3.2±1.9mm，最大为 8.0mm。基于轮廓的优化的 maxDTA 为 1.8±1.3mm，最大为 5.7mm。对两种 4 自由度优化算法的补偿参数的 Pearson 相关性比较表明，y 和 z 方向存在较小但具有统计学意义的相关性 (分别为 0.236 和 0.300)，而 x 和滚转方向的相关性非常弱 (分别为 0.062 和 0.025)。
我们发现，从 4 自由度骨性解剖自动配准到 4 自由度轮廓优化，PTV 的最大 DTA 平均提高了约 1mm。对两种 4 自由度优化的 Pearson 相关性分析表明，变形和分辨率不足引起的不确定性是补偿参数的主要来源，但俯仰变化也具有统计学意义的贡献。
