What to Expect From IMRT (Intensity-Modulated Radiation Therapy)

Medically Reviewed by Jennifer Robinson, MD on August 14, 2022
Written by Kendall K. Morgan
4 min read

IMRT is short for intensity-modulated radiation therapy. It’s a type of treatment for cancer. In IMRT, doctors use a computer to send radiation right to the tumor. This way they don’t hit healthy tissue.

Doctors use this type of radiation to treat many types of cancer, including prostate, head and neck, lung, brain, stomach, breast, and others. If you’re thinking about having this treatment, you probably wonder what it’s like.

IMRT uses a linear accelerator, a computer-controlled machine that’s about the size of a small car. It sends high-energy radiation or X-rays to cancers.

IMRT doesn’t hurt. You shouldn’t feel anything during treatment. But the machine will be noisy. You may also notice a smell from the machine or see flashing lights.

During treatment, you’ll have to lie still. You’ll be alone in the room, but your therapist will be able to see you and talk to you throughout.

IMRT takes a team. A radiation oncologist is the main doctor who will oversee this treatment. They will decide how much radiation you need and will help with any side effects. The care team also may include:

  • A radiation physicist makes sure the machine that sends radiation is working right.
  • A dosimetrist makes sure you get the right amount of radiation.
  • A radiation nurse will help take care of you during your treatment and will help to answer your questions.
  • A radiation therapist will make sure you are in the right position during treatment. They will also run the machine.

Before your first treatment, your doctors will plan carefully. They’ll take 3D pictures of your tumor to decide how much radiation you need. Your care team also uses these pictures to make sure the radiation goes to the right place.

Once a doctor runs any needed tests, they may ask you to come in for a simulation appointment. This is a practice run. A radiation therapist will show you the equipment. You’ll lie down in the right position. The therapist will mark your skin in the place where the radiation will go.

Your doctor might tell you to take certain steps to get your bowels or bladder ready before your procedure. You may also need to not eat for a time before you go in.

The time it takes will depend on the nature of the cancer and treatment plan. Usually, an IMRT treatment takes about 10 to 30 minutes. You may be in the treatment room for up to an hour, but every cancer is different. It’s a good idea to ask your doctor what to expect in your particular case.

While each procedure will be short, you’ll need more than one. Doctors usually give IMRT 5 days a week for several weeks. Exactly how many times you will go also will depends on your particular cancer and treatment plan.

Radiation therapy can come with side effects. Some may happen soon after treatment and others may happen later. The chance of certain side effects will depend on where your cancer is and how high the dose of radiation will be. Because IMRT doesn’t hit healthy cells, it may have fewer side effects than other forms of radiation therapy.

Some possible early side effects include:

Long-term side effects are rare. Some possible ones include:

  • Infertility
  • Secondary cancer
  • Changes to your mouth, kidneys, brain, spinal cord, joints, or other parts of your body
  • Swelling caused by a blockage in the lymph system

While you’re having IMRT, you’ll need to take care of yourself so that you feel as strong as possible and lessen any side effects as much as you can. During your treatment:

You’ll also need to take special care of your skin. During radiation therapy,

  • Wear loose clothing in soft fabrics like cotton or silk.
  • Don’t scratch or rub the treated area.
  • Don’t put anything hot or cold, like an ice pack or heating pad, on the treated area. Use only lukewarm water when you take a shower or bath.
  • Ask your care team before you shave the treated area or use things like lotion, deodorant, or soaps.
  • Keep the treated area out of the sun. The skin there will be very sensitive and can burn easily.

After treatment, your doctor will likely want to see you at regular intervals to find out how well it worked. They will also watch and help with any side effects. It’s likely you will continue to see your doctor for follow up for at least a couple of years after your treatment.