Non-invasive tumor localization by 3D registration of range sensor and computer tomography images.

This paper describes a patient positioning method that allows a non-invasive localization of tumors in the field of conformal radiotherapy for the treatment of cancers located in the head. The proposed methodology uses computer tomography and range sensor images of the patient´s head; on the one hand tomography data has information of tumor localization related to the patient´s head and on the other hand range sensor images has information of patient´s face localization into the treatment´s room. A 3D multimodality registration of computer tomography and range sensor images and the calibration of range sensor at radiotherapy treatment room avoid the use of stereotactic frame for patient´s positioning. Tests performed with human data proved that the registration algorithm is accurate (0.1 mm mean distance between homologous points) and robust even for facial expression changes.