What Happens During External Beam Radiation Treatment for Prostate Cancer

You can receive external beam radiation treatment (EBRT) as an outpatient. That means you may have it at a hospital or a clinic, but you don't have to stay the night. Usually you'll get treatment five days a week for a total of seven to nine weeks, depending on the type and dose of EBRT you get.

This type of radiation usually comes from a machine called a linear accelerator. These are the three kinds of EBRT commonly used to treat prostate cancer.

• Standard EBRT. This type of EBRT directs radiation at your prostate from one direction. You lie on a table while the machine is placed over you. The experience is much like that of getting an X-ray, only it lasts longer. It takes about 30 minutes for the whole process. You'll get radiation for about five minutes of that.

• Conformal EBRT. This newer type of EBRT directs radiation at your prostate from several directions to help minimize the doses to surrounding healthy tissues. Some types of conformal EBRT use higher doses of radiation for shorter periods of time. Other types use protons instead of radiation. Both of these variations reduce the damage to healthy tissue. Each treatment only lasts a few minutes.

• Intensity-modulated radiation therapy (IMRT). This is a high-precision type of radiotherapy. It uses a computer to control both the shape and strength of the X-rays to precisely deliver radiation to specific places within a tumor, while minimizing the radiation exposure to surrounding normal tissues.

Standard EBRT is not used much anymore. Most doctors now recommend conformal EBRT or IMRT if it is available.  

Preparing for radiation therapy

Before having EBRT, you may need to have a lymph node biopsy to see if your cancer has spread outside the prostate gland. You may be able to have the biopsy done laparoscopically. That means you'll have a few small incisions and the nodes will be removed with special, long tools inserted into the incisions. Or you may need a larger incision under your belly button to remove them.

Before your first radiation treatment, you'll have an appointment to plan exactly where on your body the radiation beam needs to be directed. This process is called simulation. The appointment may take up to two hours. Here's what you can expect to happen during it:

• You'll lie still on a table while a radiation therapist uses a machine to define your treatment fields. These are also called treatment ports. The field is the exact area on your body where the radiation will be aimed. You may have more than one treatment field if you have cancer in more than one place. The therapist may mark your skin with tiny dots of colored permanent ink tattoos so that the radiation will be aimed at the exact same place each time.

• You may also have imaging scans, such as CT scans, to help doctors know the exact location of your tumor to better aim the radiation.

• If you're having conformal EBRT, you may need to have a plastic mold of your body made to help you lie still during the treatment.

Some centers now use image guided radiation therapy (IGRT), which involves getting images of the prostate each day before treatment to adjust for the small changes in position of the prostate from day to day.