External Beam Radiation Therapy: A Patient's Fact Sheet
National Cancer Institute
About the treatment:
What is external beam radiation therapy?
- It is a common cancer treatment that uses high doses of radiation to destroy cancer cells and shrink tumors.
- A large machine aims radiation at the cancer. The machine moves around you without touching you.
- It doesn’t hurt.
- It doesn’t make you radioactive.
- It can’t be seen, felt, or smelled.
How does treatment work?
- At low doses, radiation is used as an x-ray to take pictures inside your body. In cancer treatment, higher doses of radiation are used to destroy cancer cells.
- The radiation that destroys cancer cells also injures nearby healthy cells. This is why you may have some side effects.
How long does treatment take?
- The length of your treatment depends on your type and stage of cancer.
- Most treatments take 2 to 10 weeks.
- Most people get treatment once a day for 5 days in a row. Treatment usually happens on Monday through Friday. Sometimes, people get treatment twice in 1 day.
- Most treatment visits last for 30 minutes to 1 hour. You will get radiation for only 1 to 5 minutes, but you may be in the treatment room for 15 to 30 minutes. Your visit may be longer if you have other tests done.
External Beam Radiation Therapy
Before treatment starts:
You will meet with a doctor or nurse before your first treatment. He or she will tell you how the treatment works and how it can help you. You will also learn about any side effects to expect. Be sure to ask any questions you have.
Your first meeting:
- You will get a checkup (physical exam). You and your doctor will talk about your health and medical history.
- You might get tests, such as x-rays or CT scans.
- Your radiation therapist will put small marks (tattoos or dots of colored ink) on your skin. These marks show where to aim the radiation.
- A body mold or mask might be made at this meeting. It will help you stay still during your treatment sessions.
During your treatment:
- You will probably lie down on a treatment table.
- Your radiation therapist will be in the next room to control the machine. He or she will be able to see, hear, and talk with you through a speaker at all times.
- You will need to stay very still, but you won’t have to hold your breath.
- You may see lights pointed at you. They are safe and show the therapist where to aim the radiation.
When you go for treatment:
- Don’t have powder, deodorant, Band-Aids®, or jewelry near your treatment area.
- Wear loose-fitting, comfortable clothes.
Ask your doctor or nurse about side effects from this treatment.