Novel tracer for radiation treatment planning

PET and PET/CT with innovative tracers gain increasing importance in diagnosis and therapy management, and radiation treatment planning in radio-oncology besides the widely established FDG. The introduction of [18F]Fluorothymidine ([18F]FLT) as marker of proliferation, [18F]Fluoromisonidazole ([18F]FMISO) and [18F]Fluoroazomycin-Arabinoside ([18F]FAZA) as tracer of hypoxia, [18F]Fluoroethyltyrosine ([18F]FET) and [11C]Methionine for brain tumour imaging, [68Ga]DOTATOC for somatostatin receptor imaging, [18F]FDOPA for dopamine synthesis and radioactively labeled choline derivatives for imaging phospholipid metabolism have opened novel approaches to tumour imaging. Some of these tracers have already been implemented into radio-oncology: Amino acid PET and PET/CT have the potential to optimise radiation treatment planning of brain tumours through accurate delineation of tumour tissue from normal tissue, necrosis and edema. Hypoxia represents a major therapeutic problem in radiation therapy. Hypoxia imaging is very attractive as it may allow to increase the dose in hypoxic tumours potentially allowing for a better tumour control. Advances in hybrid imaging, i.e. the introduction of MR/PET, may also have an impact in radio-oncology through synergies related to the combination of molecular signals of PET and a high soft tissue contrast of MRI as well as functional MRI capabilities. (orig.)