Gilhuijs K G, van Herk M
The Netherlands Cancer Institute (Antoni van Leeuwenhoek Huis), Amsterdam.
Med Phys. 1993 May-Jun;20(3):667-77. doi: 10.1118/1.597016.
A new method is presented for inspection of patient setup in radiation therapy by automatic comparison of the patient position relative to the beam position in portal and simulator images. Quantification of patient-setup errors in terms of translation, rotation, and magnification is achieved by chamfer matching, a robust technique to match drawings and images, which is applied to both anatomy outlines and field edges. Applied to field edges, chamfer matching detects and visualizes deviations in field shape. Applied to anatomy outlines, the matching procedure quantifies and visualizes deviations in patient position relative to the radiation field. To test the method and to judge its feasibility, its behavior for four hundred different patient-setup deviations, which were simulated in four clinical images, was examined. These images show a top view of the pelvic region. The performance was measured in terms of accuracy and success rate for numerous cost functions and distance codings associated with the chamfer matching procedure. An average accuracy of 1.8 mm was found, a success rate of 90%, and an average overall computation time of 3 s on a 486 microcomputer. The whole analysis procedure is fast enough to allow on-line application.
本文提出了一种新方法，通过自动比较患者在射野图像和模拟图像中相对于射束位置的位置，来检查放射治疗中的患者摆位。通过倒角匹配实现了对患者摆位误差在平移、旋转和放大方面的量化，倒角匹配是一种用于匹配图形和图像的稳健技术，应用于解剖轮廓和射野边缘。应用于射野边缘时，倒角匹配可检测并可视化射野形状的偏差。应用于解剖轮廓时，匹配过程可量化并可视化患者相对于辐射野的位置偏差。为测试该方法并判断其可行性，研究了其在四张临床图像中模拟的四百种不同患者摆位偏差情况下的表现。这些图像展示了骨盆区域的俯视图。针对与倒角匹配过程相关的众多代价函数和距离编码，从准确性和成功率方面对性能进行了测量。在一台486微机上发现平均准确性为1.8毫米，成功率为90%，平均总计算时间为3秒。整个分析过程足够快，可允许在线应用。
