Serial MRI Scans During Radiation Therapy

Inclusion Criteria: * Participants must have a confirmed malignancy requiring radiation therapy. * Age: 18 years or older except where otherwise specified in subprotocol. * ECOG performance status ≤2 (Karnofsky ≥60%) * Ability to understand and the willingness to sign a written informed consent document. * Any further criteria listed in the specific disease site subprotocol. * (Esophageal cohort) Patients must be considered appropriate candidates for neoadjuvant chemoradiation therapy followed by esophagectomy. Patients must have an endoscopic ultrasound done or scheduled to be done at the baseline visit. * (Glioblastoma cohort) Patients with a histologically confirmed newly diagnosed intracranial glioblastoma or gliosarcoma who will be undergoing radiation therapy as part of clinical care. * (Prostate cohort) Patients with localized prostate cancer who are planning to receive androgen deprivation therapy and definitive radiation therapy. * (Vulvar cohort) Patients with biopsy-proven locally advanced vulvar cancer for which definitive radiotherapy is planned. * (Pediatric glioma cohort) Patients age 18 or under (patients 18-30 years old are also eligible if the physician determines that based on genetics, the tumor biology is consistent with pediatric high grade glioma). Patients with a histologically confirmed newly diagnosed high-grade glioma (WHO grade III or IV) who will be undergoing radiation therapy as part of clinical care. Patients with DIPG are only eligible if biopsy-confirmed high grade DIPG is present. Ability to understand and/or willingness of their parent or legally authorized representative to sign a written informed consent document. Exclusion Criteria: * Disease-specific exclusion criteria will be specified in a subprotocol. * For MRI involving contrast, history of allergic reactions attributed to gadolinium-based IV contrast. If patient will not receive contrast, this is not applicable and kidney function will not affect eligibility. * Inability to undergo magnetic resonance imaging (MRI).