Interactive image registration tool for positioning verification in head and neck radiotherapy

This paper presents the development of a computer-aided image management tool, named CAIMT, used for patient setup error measurement in radiation treatment planning. The CAIMT incorporates user interaction to facilitate contour detection from both portal film and simulation film. The detected contours were then used as features for image registration through application of the generalized Hough transform (GHT). Positioning error was measured when the optimal registration was achieved. The CAIMT has been applied to register the image pairs of a randoTMrandoTM phantom and five real subjects, in order to evaluate its reliability and stability. The promising results suggest that the CAIMT can assist radiotherapists to align the simulation film and the portal film precisely and steadily and therefore adjust patient positioning to the optimum in a more efficient way.