Background and purpose: Focused dose escalation may improve local control in head and neck cancer. Planning results of [(18)F]fluoro-deoxy-glucose positron emission tomography ([(18)F]FDG-PET) voxel intensity-based intensity-modulated radiation therapy (IMRT) were compared with those of PET contour-based IMRT.
Patients and methods: PET contour-based IMRT aims to deliver a homogeneous boost dose to a PET-based subvolume of the planning target volume (PTV), called PTV(PET). The present PET voxel intensity-based planning study aims to prescribe the boost dose directly as a function of PET voxel intensity values, while leaving the dose distribution outside the PTV unchanged. Two escalation steps (2.5 and 3 Gy/fraction) were performed for 15 patients.
Results: PTV(PET) was irradiated with a homogeneous dose in the contour-based approach. In the voxel intensity-based approach, one or more sharp dose peaks were created inside the PTV, following the distribution of PET voxel intensity values.
Conclusions: While PET voxel intensity-based IMRT had a large effect on the dose distribution within the PTV, only small effects were observed on the dose distribution outside this PTV and on the dose delivered to the organs at risk. Therefore both methods are alternatives for boosting subvolumes inside a selected PTV.