Before your first radiation treatment, you'll have an appointment called simulation. This is needed to find exactly where on your body the radiation beam needs to be directed. It may take up to 2 hours. During this session, imaging tests, such as an MRI or CT scans, may be done. These tests help your healthcare providers know exactly where the tumor is so they can aim the radiation right at it. Also at this session, body molds might be made. These are done to put you in the exact same position and help keep you from moving during treatments.
Then you'll lie still on a table while a radiation therapist uses a machine to define your treatment field. The field is the exact place on your body where the radiation will be aimed. Sometimes it's called your port. The therapist may mark your skin with tiny dots of semipermanent ink or tattoos. This is so the radiation will be aimed at the exact same place each time.