Validation of Deformable Registration of Prostate MRI with and Without Endorectal Coil for IMRT Planning

Marnix Christiaan Maas¹, Corijn Kamerling¹, Simon van Kranen¹, Sara Muller², Jelle Teertstra², Floris Pos¹, Christoph Schneider¹, Jan Jakob Sonke¹, Marcel van Herk¹

Using an endorectal coil (ERC) greatly improves the quality of prostate MR images, but results in displacements and deformations of the organ and its surrounding tissues, causing systematic errors in intensity modulated radiation therapy (IMRT) planning. We have implemented an image based method for the deformable registration of endorectal to non-endorectal MR images. Here we present a validation of this method using markers placed on corresponding anatomical structures in pairs of fixed and deformed images. The registration method was found to be feasible, and our results suggest that sufficient accuracy for use in radiotherapy planning is attainable.