| Hi-index | 0.00 |
In this paper, cost functions are tested for 2D registration of portal and reference images for treatment verification in radiotherapy. Tests were performed with and without pre-processing for 96 image pairs of various treatment sites. The best results were obtained when the images were preprocessed by unsharp masking and histogram equalization. This led to a success rate of about 88% and a difference with clinical registration of 1.2 mm SD and 1 degree SD for most of the tested cost functions. The number of local minima with mutual information is much larger than with the other tested cost functions.