A novel radio guided surgery (RGS) technique for cerebral tumors using $beta^{-}$ radiation is being developed. Checking the availability of a radio-tracer that can deliver a $beta^{-}$ emitter to the tumor is a fundamental step in the deployment of such technique. This paper reports a study of the uptake of 90Y labeled (DOTATOC) in the meningioma and the high grade glioma (HGG) and a feasibility study of the RGS technique in these cases.