Charles A. Pelizzari PhD, Presenter: Research grant, Varian Medical Systems, Inc

1) Understand the importance of imaging in all stages of the radiation therapy process. 2) Understand the significance of multimodality image information in radiation therapy planning and evaluation. 3) Understand the distinction between image registration and patient-image registration. 4) Understand the dependence of image guided therapy on image registration. 5) Appreciate the historical development of image registration in radiation therapy planning.

Among medical specialties concerned with treating rather than diagnosing disease, radiation oncology has long been among the most intensive in its use of imaging. Indeed, since external beam radiotherapy relies on directing an invisible beam of radiation at a target which is concealed within the patient, image guidance of one form or another has always been an essential tool of this therapeutic modality. Radiographic localization of radiation targets, either directly or more frequently in relation to other visible anatomic structures, was the norm prior to the advent of three-dimensional (3D) anatomic imaging modalities. With the clinical availability of each new imaging modality over the past 25 years - X-ray computed tomography (CT), magnetic resonance imaging (MRI), single photon (SPECT) and positron (PET) emission computed tomography, functional MRI, and the current generation of molecular imaging modalities reflecting physiologic and biologic function - physicians and physicists in radiation oncology have been quick to incorporate all relevant image information into a multimodality description of the patient. As we shall see, this multimodality image-based model finds use at all stages of the radiation therapy process, from diagnosis and planning through assessment of therapeutic effect and long-term followup. Key to the ability to make use of these multiple datasets is the technology of image registration, and there has been a great deal of work in radiation therapy in this area, some dating back twenty years. This chapter reviews the uses of image information throughout the radiation therapy process, and the specific impact of multimodality imaging and image registration at each stage. Developments in image registration technology specific to radiation therapy are highlighted.

Pelizzari, C, Image Registration in Radiation Therapy.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/4405289.html