Functional Treatment Planning Utilizing 18-FDGal PET/CT in SBRT for Liver Metastases

Background: Anatomical (traditional) stereotactic body radio therapy(SBRT) treatment planning assumes homogenous distribution of function in the normal liver tissue. In functional treatment planning, additional information on distribution of the function derived from functional imaging of normal tissue is taken into account. by functional treatment planning it becomes possible to prioritize and spare the best functioning part of an organ. Aim: To test whether functional treatment planning based on 18-FDGal PET/CT may spare the best functioning liver tissue. Endpoints: Reduction in hepatic systemic clearance (K) in the dynamic 18-FDGal PET/CT scan one month after SBRT compared to the baseline status in sub-volumes recieving 15 Gy or higher. Secondly, the investigators will evaluate the toxicity to SBRT by a toxicity scoring system that includes biochemical measures as well as symptomatic scores.