Radiation therapy (RT) is an effective treatment for patients with advanced-stage clear cell renal cell carcinoma (ccRCC). Current evidence has shown promising outcomes combining radiation therapy and standard systemic therapy in patients with metastatic/recurrent ccRCC. CAIX is a highly sensitive and specific biomarker expressed on ccRCC and in previous studies the investigators have shown excellent diagnostic efficacy of 68Ga-NY104, a CAIX-targeted PET tracer, in patients with metastatic ccRCC. In this study, the investigators aim to investigate the effect of 68Ga-NY104, and 18F-FDG PET/CT guided RT combining standard systemic therapy in patients with metastatic ccRCC.