A SURFACE-BASED DEFORMABLE IMAGE REGISTRATION WITH APPLICATION TO BREAST CANCER RADIATION THERAPY
Wanchat Theeranaew · OhioLink ETD Center (Ohio Library and Information Network) · 2008
In this paper, a new form of surface-based deformable image registration is developed for use in image-guided radiation therapy (IGRT) of breast cancer patients. A special laser scanner is used to obtain inter-fraction 3D images of the target volume, with 3-4 fixed landmarks located at the rigid base of the breast. By comparing the image-ofthe-day with the initial-fraction image, a rigid-body registration is first performed on the landmarks to correct the patient set-up position. This is then followed by a surface comparison scheme to estimate the extent of deformity of the target volume. In this paper, deformity is represented by the distance between the two surfaces. With the surface images stored as triangular meshes, deformity is determined as the collection of distances from the centers of triangular meshes of a surface to their respective closest triangular pieces of another surface. A ray-to-triangle intersection algorithm is used in the distance calculation, and a neighborhood-search technique is devised to substantially increase the calculation speed while maintaining the accuracy. Experimental measurements using phantoms were used to test the accuracy and speed of the overall image registration scheme. Preliminary results indicate that the proposed system is fast and accurate suitable for further adaptation for clinical application.