External radiation therapy is usually given on an outpatient basis in a hospital or a clinic. If you have questions about your external radiation therapy, be certain to ask your doctor before agreeing to treatment. All of your concerns should be addressed before the procedure begins.
This type of radiation usually comes from a machine called a linear accelerator.
Before your first appointment to get radiation, you will have an appointment to learn exactly where on your body the radiation beam needs to be directed. This process is called simulation.
The appointment may take up to 2 hours. Here’s what you can expect to happen during the simulation process:
You’ll lie still on a table while a radiation oncologist uses a machine, either a CT scan or an X-ray machine, to define your treatment fields. These fields may also be called your ports. This is the exact spot on your body where the radiation will be aimed. The therapist marks your skin with tiny dots of colored permanent ink or tattoos so that the radiation can be aimed at the exact same place each time.
You may also have imaging scans. These may include diagnostic CT scans. Imaging scans help doctors know the exact location of your tumor to better aim the radiation.
You may also have body molds made to help keep you from moving during the treatment.
On the days you have radiation, you may have to change into a hospital gown. You’ll lie on a table while the machine is placed over you. The experience is like getting an X-ray, only it lasts longer. The whole process takes about 15 to 30 minutes. A radiation therapist may place blocks or special shields to protect parts of your body that don’t need to be exposed to radiation. The therapist also lines up the machine exactly with your marked treatment fields, located during the earlier simulation process. Each time the beam goes on, it will go on for 20 to 30 seconds and will go on several times during each treatment day.
The radiation therapist will leave the room to turn on the machine, but you will be able to talk to him or her over an intercom. You can’t feel radiation. You may hear whirring or clicking noises. Most treatment plans require that you get radiation treatments every day for 5 days in a row for several weeks. You will not be radioactive afterward, so don’t worry about that.