PET-CT in radiation oncology - The impact on diagnosis, treatment planning, and assessment of treatment response

Objective: To review the role of hybrid positron emission tomography (PET)-computed tomography (CT) systems in the design and management of cancer patients in the modern radiation oncology practice. PET is co-registered with CT and incorporated into a systematic approach to the staging, management, and assessment of response and surveillance of a variety of oncologic diagnoses. Methods: A review of the literature of functional imaging such as PET-C-T in staging, treatment plan design, assessment of response and detection of recurrence for tumors involving the head and neck, lung, esophagus, rectum amongst others. Results: PET and PET-CT offer significant advantages which include more accurate staging which often results in management changes in roughly one-third of patients across a number of disease site. More accurate target definition may augment highly conformal radiation treatment plans using intensity-modulated radiation therapy and stereotactic radiosurgery and radiotherapy. Conclusion: The emerging data appears to suggest the functional imaging may be a more useful tool to evaluate the therapeutic effect of treatment, detect early failures and prognosticate long-term outcome.