Dose-Effect Relation of Salivary Gland Irradiation

Optimization of radiotherapy to reduce xerostomia is difficult, because many gland locations cannot be seen with current imaging modalities and biological dose-effect are currently insufficiently understood. PSMA PET is a new diagnostic instrument which can visualize the presence of vital acinar cells in salivary gland locations throughout the head and neck, with a sensitive and quantitative signal. A reduction of PSMA accumulation in salivary glands is thought to correlate with loss of vital acinar cells. The PET images can be correlated with radiotherapy dose distributions in gland-based or voxel-based evaluations. This makes PSMA PET a suitable instrument to derive the radiobiological dose-effect relations that are required to develop better and gland-specific dose constraints for radiotherapy. The results of this study can contribute to lower toxicity and better quality of life in patients treated with high-dose radiotherapy in the head and neck.