Types of Radiation Therapy

There are two main types of radiation therapy: external beam radiation therapy and internal radiation therapy.

External Beam Radiation Therapy

External beam radiation therapy comes from a machine that aims radiation at your cancer. The machine is large and may be noisy. It does not touch you, but can move around you, sending radiation to a part of your body from many directions.

External beam radiation therapy treats a specific part of your body. For example, if you have cancer in your lung, you will have radiation only to your chest, not to your whole body.

Internal Radiation Therapy

Internal radiation therapy is a treatment in which a source of radiation is put inside your body. The radiation source can be solid or liquid.

Internal radiation therapy with a solid source is called brachytherapy. In this type of treatment, radiation in the form of seeds, ribbons, or capsules is placed in your body in or near the cancer.
You receive liquid radiation through an IV line. Liquid radiation travels throughout your body, seeking out and killing cancer cells.

Radiation Therapy Side Effects

Radiation not only kills or slows the growth of cancer cells, it can also affect nearby healthy cells. Damage to healthy cells can cause side effects. External radiation and brachytherapy cause side effects only in the part of the body being treated.

The most common side effect of radiation therapy is fatigue, which is feeling exhausted and worn out. Fatigue can happen all at once or little by little. People feel fatigue in different ways. You may feel more or less fatigue than someone else who is also getting radiation therapy.

You can prepare for fatigue by:

  • Asking someone to drive you to and from radiation therapy
  • Planning time to rest
  • Asking for help with meals and childcare

Healthy cells that are damaged during radiation treatment almost always recover after it is over. But sometimes people may have side effects that are severe or do not improve. Other side effects may show up months or years after radiation therapy is over. These are called late effects.

Doctors try to protect healthy cells during treatment by:

Using as low a dose of radiation as possible

The radiation dose is balanced between being high enough to kill cancer cells, yet low enough to limit damage to healthy cells.

Spreading out treatment over time

You may get radiation therapy once a day, or in smaller doses twice a day for several weeks. Spreading out the radiation dose allows normal cells to recover while cancer cells die.

Aiming radiation at a precise part of your body

With external radiation therapy, for example, your doctor is able to aim high doses of radiation at your cancer while reducing the amount of radiation that reaches nearby healthy tissue. These treatments use a computer to deliver precise radiation doses to a tumor or to specific areas within the tumor.