Functional imaging applied to radiotherapy
Ilja F Ciernik, J Bernard Davis, Gabor Szekely
Oncology Institute of Southern Switzerland (IOSI), Bellinzona, Switzerland
Positron emission tomography (PET) in combination with computer tomography (PET/CT) increases the accuracy of target volume assessment. PET signals are easily accessible to highly reproducible software-based target volume definition and reduce inter-observer variability. PET signals can provide structures corresponding to GTV, as in head and neck cancer or CTV, as in prostate and breast cancer. Disease- and tracer-specific interpretation applies. In the present paper, we review our experience with software-based target volume assessment and the utility of 18-FDG-PET-based radiotherapy planning. We will discuss the ability how PET influences the target volume. A software (SW) for the purpose of PET-based target delineation will be demonstrated. The presented SW is intuitive, robust and easy to use. It can be directly implemented in the planning process without additional tools. For target volume definition, the algorithm can be used clinically but for the final volume delineation CT or MRI data must be taken into account. Its major advantage lies in the potential that PET-based treatment planning can provide a standardized first line target volume. This approach leaves the clinician with a working volume, which may be ultimately adapted in a second step. Such a procedure may speed the planning process, reduce time delays during planning, and may allow a more rapid start of treatment. The potentials of adaptive radiotherapy will be discussed.
