Serial MRI Scans During Radiation Therapy

This is a phase 1, non-randomized, open-label study evaluating feasibility of serial MRI, with an option for an expansion cohort. The optional expansion cohort is a prospective imaging registry evaluating imaging biomarkers as predictors of disease control with standard of care treatment. This research study is a feasibility study, meaning that it is the first time that investigators at this institution are examining the process of getting multiple MRIs during radiation treatment. The U.S. Food and Drug Administration (FDA) has cleared this MRI scanner for use. Participants who fulfill eligibility criteria will be entered into the trial. The research study procedures include screening for eligibility, and three MRI scans. MRI imaging will be performed as per disease site standards. A total of 149 participants will be enrolled in this trial: * 13 participants in the esophageal cancer cohort * 10 participants in the initial glioblastoma cohort and 36 participants in the image registry expansion cohort * 10 participants in the prostate cancer cohort and 50 participants in the image registry expansion cohort * 10 participants in the vulvar cancer cohort * 10 participants in the pediatric glioma cohort * 10 participants in the sarcoma cohort