Krell Gerald, Saeid Nezhad Nazila, Walke Mathias, Al-Hamadi Ayoub, Gademann Günther
Institute for Information Technology and Communication Engineering, Otto-von-Guericke University Magdeburg, Universitätsplatz 2, 39016 Magdeburg, Germany.
Clinic for Radiotherapy, Otto-von-Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany.
Comput Math Methods Med. 2017;2017:2938504. doi: 10.1155/2017/2938504. Epub 2017 Jan 9.
An optical 3D sensor provides an additional tool for verification of correct patient settlement on a Tomotherapy treatment machine. The patient's position in the actual treatment is compared with the intended position defined in treatment planning. A commercially available optical 3D sensor measures parts of the body surface and estimates the deviation from the desired position without markers. The registration precision of the in-built algorithm and of selected ICP (iterative closest point) algorithms is investigated on surface data of specially designed phantoms captured by the optical 3D sensor for predefined shifts of the treatment table. A rigid body transform is compared with the actual displacement to check registration reliability for predefined limits. The curvature type of investigated phantom bodies has a strong influence on registration result which is more critical for surfaces of low curvature. We investigated the registration accuracy of the optical 3D sensor for the chosen phantoms and compared the results with selected unconstrained ICP algorithms. Safe registration within the clinical limits is only possible for uniquely shaped surface regions, but error metrics based on surface normals improve translational registration. Large registration errors clearly hint at setup deviations, whereas small values do not guarantee correct positioning.
光学三维传感器为在断层放射治疗机上验证患者是否正确就位提供了一种额外的工具。将患者在实际治疗中的位置与治疗计划中定义的预期位置进行比较。一种商用光学三维传感器可测量身体表面的部分区域，并在无标记的情况下估计与期望位置的偏差。针对治疗床的预定义位移，研究了内置算法和选定的迭代最近点（ICP）算法在由光学三维传感器捕获的特殊设计体模表面数据上的配准精度。将刚体变换与实际位移进行比较，以检查预定义极限下的配准可靠性。所研究体模的曲率类型对配准结果有很大影响，对于低曲率表面更为关键。我们研究了所选体模的光学三维传感器的配准精度，并将结果与选定的无约束ICP算法进行比较。只有对于形状独特的表面区域，才有可能在临床极限内实现安全配准，但基于表面法线的误差度量可改善平移配准。较大的配准误差明显表明设置存在偏差，而较小的值并不能保证定位正确。
