Dual-Energy CT on Plan Quality, Dose-delivery Accuracy, and Simulated Outcomes of Patients Treated With Proton or Photon Therapy

Eligibility Criteria: Inclusion Criteria: * Diagnosis of histologically proven primary or metastatic cancer requiring thoracic radiation therapy OR radiation therapy to the head and neck or brain * At least 18 years of age. * Planning to undergo proton or photon beam radiation therapy as part of the clinical management of the diagnosed cancer. * Able to understand and willing to sign an IRB-approved written informed consent document. Exclusion Criteria: * Implanted metallic objects in the region to be scanned excepting dental prostheses * IV or oral contrast medium within 24 hours prior to DECT image acqusition * Pregnant.