A hospital is considering two different patient cases for a brain scan. Case 1 involves a 70-year-old patient who has suddenly lost the ability to speak, and doctors suspect a major stroke or a fast-growing tumor. Case 2 involves a healthy 25-year-old athlete who wants a scan for 'peace of mind' before a major competition, despite having no symptoms. Considering that some brain imaging techniques involve exposing the patient to radiation, which case presents a more ethically and medically sound justification for using such a technique? Defend your choice.