If someone has had multiple abdominal ct scans i'm their early 20s and damaged dna, could a healthy diet prevent the damage from turning into cancer? or is the risk inevitable after the ct scans?

Not directly prevent: But the American Cancer Society says... cancer is often unpredictable, but there are things everyone can do to help reduce their cancer risk. Get regular cancer screening tests, such as for breast, cervical, or colon cancer. Stay at a normal healthy weight. Exercise regularly, such as 20-30 minutes, 4-5 times a week. Eat a healthy diet. Avoid tobacco. Limit or avoid alcoholic drinks.