PET/CT of cancer patients: part 2, deformable registration imaging before and after chemotherapy for radiation treatment planning in head and neck cancer.

OBJECTIVE: The purpose of this perspective is to discuss the use of deformable registration as a tool for image fusion to integrate information from PET/CT scans obtained before and after chemotherapy to assist definition of radiation targets in the management of head and neck cancer.
CONCLUSION: The consistent method for target delineation described capitalizes on the capability of deformable registration to compensate for changes in position and accurately represent evolving spatial relationships between normal anatomy and areas at risk of disease.