Inclusion Criteria:  Histologically confirmed solid tumor disease One to three resected brain metastases Consent to perform adjuvant irradiation by an interdisciplinary tumor board Completed wound healing Resection within the last six weeks at the time of study inclusion Diameter of the resection cavity ≤ 4 cm (on Planning MRI) Age > 18 years KPS > 60% Adequate contraceptive measures for fertile women / men Written informed consent (must be available before enrolment in the trial)  Exclusion Criteria:  Contraindication for repetitive contrast enhanced MRI Leptomeningeal disease Small cell histology, hematological malignancies and / or germ cell malignancies Previous irradiation of the brain Pregnant and lactating women Inability to understand the character and consequences of the study Withdrawal of consent