In this study, we plan to systematically analyze the motion of organs and tissues in the abdomen, to understand the physical mechanisms of three-dimensional (3D) motion and interactions of abdominal organs and tissues. This work will allow us to learn how to mathematically model and predict abdominal organ motion.

Specifically, we plan to conduct this study in 3 steps, in an order of increasing complexity, starting with the (intra-fractional) respiratory only motion, then adding intra-fractional GI motility motion, and finally the inter-fractional anatomical variations (adding food intakes and fecal excretion). The research methods described will allow the study team to develop the ability to estimate the motion of both tumor target and critical organs given the patient's MRI, CBCT or x-ray fluoroscopy images on the day of radiation treatment.

Inclusion Criteria:

• No contraindications for MRI (e.g., unsafe MRI implanted devices, shrapnel, history of metal fragments in eyes, neurostimulators, body habitus, claustrophobia).
• May have pre-existing medical conditions provided they are capable of completing the exam and their condition is not expected to affect the physical tissue properties of the organs that will be imaged.
• Women of child-bearing potential must verbally confirm lack of pregnancy prior to signing consent

Exclusion Criteria:

• None