Measurement of inter and intra fraction organ motion in radiotherapy using cone beam CT projection images
Measurement of inter and intra fraction organ motion in radiotherapy using cone beam CT projection images
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DOI：
10.1088/0031-9155/53/4/018
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发表时间：
2008-02-21
影响因子：
3.5
通讯作者：
Moore, C. J.
中科院分区：
文献类型：
--
作者：
Marchant, T. E.;Amer, A. M.;Moore, C. J.
提出了一种从锥形束CT （CBCT）投影图像中提取患者体内种子/标记物的内部和内部运动的方法。在每个投影图像上确定标记的位置，并拟合到描述以不同龙门形角度将固定点投影到成像面板上的函数。拟合的参数提供了相对于等心的平均标记位置。利用理论函数与实际投影标记点位置的差值来估计区内运动范围和横平面上的主运动轴。利用已知位置的静态标记和已知幅度移动标记的CBCT投影图像验证了该方法。在所有方向上，实际运动范围与测量运动范围的平均差异小于1毫米，尽管在正交方向上出现大幅度运动时，误差可达5毫米。在这些情况下，有可能计算出与观察到的标记轨迹一致的运动幅度范围。该方法通过胰腺癌患者的临床CBCT投影显示是可行的。
A method is presented for extraction of intra and inter fraction motion of seeds/ markers within the patient from cone beam CT ( CBCT) projection images. The position of the marker is determined on each projection image and fitted to a function describing the projection of a fixed point onto the imaging panel at different gantry angles. The fitted parameters provide the mean marker position with respect to the isocentre. Differences between the theoretical function and the actual projected marker positions are used to estimate the range of intra fraction motion and the principal motion axis in the transverse plane. The method was validated using CBCT projection images of a static marker at known locations and of a marker moving with known amplitude. The mean difference between actual and measured motion range was less than 1 mm in all directions, although errors of up to 5 mm were observed when large amplitude motion was present in an orthogonal direction. In these cases it was possible to calculate the range of motion magnitudes consistent with the observed marker trajectory. The method was shown to be feasible using clinical CBCT projections of a pancreas cancer patient.