Imaging Study on Halcyon 4.0 System for Patients Receiving Radiation Therapy

Eligibility Criteria: * Planning to receive radiation therapy to one of the following sites: * Head and neck/brain (n=10) * Thorax (n=10) * Abdomen (n=10) * Pelvis (n=10) * At least 18 years of age * If the patient will be receiving IV contrast on study: Adequate renal function as defined by a serum creatinine \< 1.4, or, for patients with chronic kidney disease, a stable serum creatinine \< 2.0. Note: if no IV contrast will be administered on study, patient may enroll without creatinine level documented. * If the patient is a woman of childbearing potential, a negative pregnancy test must be obtained. Contraceptive use is not an adequate documentation of no chance of pregnancy. * Able to understand and willing to sign an IRB approved written informed consent document.