Inclusion Criteria:  confirmed underlying solid malignant tumor (no germ cell tumor, leukemia, lymphoma) 1-3 hepatic metastases confirmed by pre-therapeutic MRI indication for SBRT of 1-3 hepatic metastases maximum diameter each hepatic metastasis ≤ 5 cm (in case of 3 metastases: sum of diameters ≤ 12 cm) age ≥ 18 years of age Karnofsky Performance Score ≥ 60% ability to lie still on the radiotherapy treatment couch for at least one hour ability to hold one's breath for more than 25 seconds for women with childbearing potential, adequate contraception ability of subject to understand character and individual consequences of the clinical trial written informed consent (must be available before enrolment in the trial)  Exclusion Criteria:  refusal of the patients to take part in the study patients with primary liver cancer (eg. HCC, CCC) patients after liver transplantation impairment of liver function to an extent contraindicating radiotherapy (to the discretion of the treating radiation oncologist) active acute hepatic/biliary infection (e.g. hepatitis, cholangitis, cholecystitis) previous radiotherapy of the hepatobiliary system, if previous and current target volumes overlap MAESTRO Study Studienprotokoll Seite 25 von 54 Version 1.0 vom 17.12.2020 patients who have not yet recovered from acute toxicities of prior therapies claustrophobia pregnant or lactating women contraindications against performing contrast-enhanced MRI scans (pacemakers, other implants making MRI impossible, allergy to gadolinium (GD)-based contrast agent) participation in another competing clinical study or observation period of competing trials