GI Organ Tracking Via Balloon Applicators

Inclusion Criteria: * Scheduled to receive intra-thoracic or abdominal radiation therapy. It is not required that the stomach be in the radiation field. * At least 18 years of age. * ECOG performance status ≤ 1 * Ability to understand and willingness to sign an IRB approved written informed consent document (or that of legally authorized representative, if applicable). Exclusion Criteria: * Prior trauma or surgical intervention that would alter the anatomy of the upper airs (nasogastric route), esophagus or stomach. * Previous complete or partial surgical resection of the esophagus, stomach, or duodenum. * Presence of implantable devices (e.g., automatic internal cardiac defibrillator, cardiac or gastric pacemaker).