 Helical Tomotherapy HT allows as a sole modality a new treatment option: Using HT, the advantage of applying a highly conformal boost dose to the metastases and WBRT can be combined in one treatment session. Therefore, it allows applying a high dose to multiple brain metastases in the sense of an integrated boost. The focus of this study is to investigate the efficacy and safety of WBRT with an integrated boost using this new treatment modality in comparison to the effects of conventional WBRT alone. 