Multivariate analysis for the estimation of target localization errors in fiducial marker-based radiotherapy
Multivariate analysis for the estimation of target localization errors in fiducial marker-based radiotherapy
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DOI：
10.1118/1.4944594
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发表时间：
2016-04-01
期刊：
影响因子：
3.8
通讯作者：
Itoh, Akio
中科院分区：
文献类型：
--
作者：
Takamiya, Masanori;Nakamura, Mitsuhiro;Itoh, Akio
目的：根据从代理估计的目标和定位点之间的距离来评估目标定位误差（TLE）（垂直条TMD垂直条），替代物和目标的呼吸运动的平均值（垂直条）和用于估计目标的基准标记的数量（n）。这项研究招募了17名肺癌患者，他们随后接受了四次实时肿瘤跟踪照射。在肺肿瘤周围植入四个或五个基准标记。肿瘤和标记物之间的三维（3D）距离最大为58.7 mm。将其中一个标记物用作目标（P-t），并选择3D垂直条TMDn垂直条= 10 mm的标记物。最后，对于n = 1、2和3，分别获得了总共205、282和76个满足3D垂直杆TMD垂直杆和3D垂直杆aRM垂直杆标准的TLE。采用多元回归分析（MRA）评估TLE作为垂直条、TMD垂直条和垂直条aRM垂直条的函数。结果：垂直条TMD n = 1的垂直条大于n = 3的垂直条。此外，垂直条和RM垂直条对于所有n几乎是恒定的，表明标记物在肺肿瘤附近的运动的相似尺度。MRA显示左右方向的垂直条和RM垂直条是TLE的主要原因，但由于左右方向的运动量较小，因此对3D TLE的贡献差异不大。由MRA计算的TLE（（TLE）-T-MRA）随垂直条TMD垂直条和垂直条aRM垂直条的增加而增加，随n的增加而减少。中位3D（TLE）-T-MRA为2.0 mm（范围：0.6-4.3 mm）（n = 1）、1.8 mm（范围：0.4-4.0 mm）（n = 2）和1.6 mm（范围：0.3-3.7 mm）（n = 3）。虽然n = 1和n = 3之间在各个方向上观察到统计学意义，但n = 1和n = 3之间的（TLE）-T-MRA的绝对平均差和标准差分别为0.5和0.2mm。然而，3D（TLEs）-T-MRA的差异最多为0.6 mm。因此，作者得出结论，只要垂直杆TMD垂直杆保持在≤ 10 mm，就可以继续基于基准标记的放射治疗。（C）2016年美国医学物理学家协会。
Purpose: To assess the target localization error (TLE) in terms of the distance between the target and the localization point estimated from the surrogates (vertical bar TMD vertical bar), the average of respiratory motion for the surrogates and the target (vertical bar aRM vertical bar), and the number of fiducial markers used for estimating the target (n).Methods: This study enrolled 17 lung cancer patients who subsequently underwent four fractions of real-time tumor tracking irradiation. Four or five fiducial markers were implanted around the lung tumor. The three-dimensional (3D) distance between the tumor and markers was at maximum 58.7 mm. One of the markers was used as the target (P-t), and those markers with a 3D vertical bar TMDn vertical bar = 10 mm were selected. Finally, a total of 205, 282, and 76 TLEs that fulfilled the 3D vertical bar TMD vertical bar and 3D vertical bar aRM vertical bar criteria were obtained for n = 1, 2, and 3, respectively. Multiple regression analysis (MRA) was used to evaluate TLE as a function of vertical bar TMD vertical bar and vertical bar aRM vertical bar in each n.Results: vertical bar TMD vertical bar for n = 1 was larger than that for n = 3. Moreover, vertical bar aRM vertical bar was almost constant for all n, indicating a similar scale for the marker's motion near the lung tumor. MRA showed that vertical bar aRM vertical bar in the left-right direction was the major cause of TLE; however, the contribution made little difference to the 3D TLE because of the small amount of motion in the left-right direction. The TLE calculated from the MRA ((TLE)-T-MRA) increased as vertical bar TMD vertical bar and vertical bar aRM vertical bar increased and adversely decreased with each increment of n. The median 3D (TLE)-T-MRA was 2.0 mm (range, 0.6-4.3 mm) for n = 1, 1.8 mm (range, 0.4-4.0 mm) for n = 2, and 1.6 mm (range, 0.3-3.7 mm) for n = 3. Although statistical significance between n = 1 and n = 3 was observed in all directions, the absolute average difference and the standard deviation of the (TLE)-T-MRA between n = 1 and n = 3 were 0.5 and 0.2 mm, respectively.Conclusions: A large vertical bar TMD vertical bar and vertical bar aRM vertical bar increased the differences in TLE between each n; however, the difference in 3D (TLEs)-T-MRA was, at most, 0.6 mm. Thus, the authors conclude that it is acceptable to continue fiducial marker-based radiotherapy as long as vertical bar TMD vertical bar is maintained at = 10 mm. (C) 2016 American Association of Physicists in Medicine.