Automatic integration of PET/CT images for clinical use in radiotherapy

We implemented an automatic method based on maximization of mutual information (MI), suitable for clinical use for registration of CT and PET images in radiotherapy planning. The integration of anatomical CT information with functional PET data allows a better definition of the tumour volume with respect to the conventional CT based approach. The accuracy of spatial realignment obtained with the proposed approach was investigated in experimental data, relative to phantom and patient studies and was found adequate for radiotherapy application. An application of the MI matching method to a patient affected by non-small lung cancer is presented, showing the differences between CT and multimodal PET/CT radiotherapy treatment plans.