Jobse Mark, Davelaar Jaap, Hendriks Emile, Kattevilder Rob, Reiber Hans, Stoel Berend
Delft University of Technology, Faculty of Electrical Engineering, Information and Communication Theory Group, P.O. Box 5031, Delft, 2600 GA, The Netherlands.
Med Phys. 2003 Sep;30(9):2274-81. doi: 10.1118/1.1592018.
The manual verification of a radiotherapy treatment, where a portal image is matched onto a planning image, is very time consuming and subject to inter- and intraobserver variability. Therefore, a fully automatic matching procedure (image registration) is required. Existing automatic matching algorithms are confounded, however, by irrelevant information in the portal images (i.e., air in the intestines). Therefore, we have developed a new method, which is an extension of chamfer matching and uses, apart from the distance to the nearest edge, additional information on the correspondence of the gradient angle and magnitude of the edges, making the method less sensitive to confounding information in the images. To validate the automatic matching procedure in clinical practice, we applied the new method on 157 images of 29 randomly selected patients treated for carcinoma of the prostate. Three experts manually matched these images in consensus. Subsequently, the same observers assessed the results of the automatic registration. When regular chamfer matching is used for the fully automatic matching procedure, only 5% of the image pairs could be matched correctly, whereas the new method successfully registered 80% by using additional information on the angle of the edges. From the results of the validation study it can be concluded that a significant reduction in workload for the physicians and technicians can be achieved with this method.
放疗治疗的人工验证，即将射野图像与计划图像进行匹配，非常耗时且受观察者间和观察者内变异性的影响。因此，需要一种全自动匹配程序（图像配准）。然而，现有的自动匹配算法会受到射野图像中无关信息（如肠道内的空气）的干扰。因此，我们开发了一种新方法，它是倒角匹配的扩展，除了到最近边缘的距离外，还使用边缘梯度角度和大小对应关系的附加信息，使该方法对图像中的干扰信息不太敏感。为了在临床实践中验证自动匹配程序，我们将新方法应用于29例随机选择的前列腺癌患者的157张图像。三位专家达成共识，手动匹配这些图像。随后，相同的观察者评估了自动配准的结果。当使用常规倒角匹配进行全自动匹配程序时，只有5%的图像对能够正确匹配，而新方法通过使用边缘角度的附加信息成功配准了80%。从验证研究的结果可以得出结论，使用这种方法可以显著减少医生和技术人员的工作量。
