 Expected results. This prospective cohort study aims to explore and evaluate patients with PCNSL who are newly-diagnosed by using a standard battery of neurobehavioral functions plus neuroimaging studies. It is anticipated investigators will investigate and correlate neurotoxicity indicators in newly-diagnosed patients with PCNSL who are treated with cranial radiotherapy combined with or without MTX-based chemotherapy according to the multidisciplinary treatment guidelines implemented at a single institute. 