Nuclear medicine imaging is becoming increasingly important in radiation oncology

not only for tumor staging

but also for treatment planning and follow-up. Positron emission tomography (PET) and single photon emission tomography (SPECT) imaging play a major role in the definition of tumor extent and staging of patients with cancer for three-dimensional and intensity modulated radiation therapy. Since the metabolic change of a tumor tissue usually precedes its morphological changes

it is possible to use these functional techniques to identify tumor tissue before it becomes visible in morphological images. 18F-FDG PET has the best sensitivity

specificity and accuracy in detecting tumor recurrence. In addition

the applications of nuclear medicine imaging for the patients with brain tumors

nasopharyngeal carcinoma

lung cancer

etc.

in the conformal radiotherapy are also reviewed.