 This is a pilot prospective, single-institution study in both healthy participants and particpants with evidence of intracranial metastases who will be planned for brain radiation therapy. Healthy particpant accural will be done through advertisments. Intracranical metastatic participant screening and accrual will be completed by a member of the participants Cirlce of Care. Clinical procedures will be completed at Sunnybrook Health Sciences Centre SHSC by the studys Qualified Investigator or medical designate. Eligible healthy particpants must meet the studys inclusion and exclusion crtieria and MRI eligibility. Intracranial metastatic particpants must meet the studys inclusion and exclusion crtieria, MRI eligibility will be undergoing radiation therapy stereotactic radiotherapy. 