This is an investigator-initiated, Phase I clinical trial. It aims to evaluate the safety, tolerability, dosimetry, and preliminary anti-tumor activity of a novel radiopharmaceutical, \[177Lu\]Lu-DOTA-EB-RGD2, in patients with recurrent high-grade gliomas. Participants will receive the drug either via intravenous infusion or directly into the tumor cavity through a pre-implanted Ommaya reservoir (a subcutaneously placed device that allows direct access to the tumor cavity). The study employs a "3+3" dose-escalation design to determine the maximum tolerated dose (MTD). Adverse events, biodistribution, and tumor response (by MRI) will be assessed. Approximately 24 patients will be enrolled across two major Chinese medical centers: Beijing Tiantan Hospital and Peking Union Medical College Hospital.