Intensity-Modulated Radiation Therapy (IMRT)

Intensity-modulated radiation therapy (IMRT) is a type of external beam radiation therapy that treats cancer. It targets tumors while avoiding healthy tissue. This makes IMRT a good treatment option when a tumor is next to sensitive organs. 

Like all external beam radiation therapy, IMRT kills cancer cells with controlled radiation beams. A machine called a linear accelerator (LINAC) directs the beams. With intensity-modulated radiation therapy, the beam can be carefully adjusted to focus radiation on the cancer area while avoiding high doses to healthy tissue.

Protecting healthy tissue from radiation exposure reduces the risk that radiation will damage that tissue. This means you may experience fewer side effects.

The LINAC never touches your body, and intensity-modulated radiation therapy doesn’t hurt. You won’t feel anything during the treatment, but some people experience side effects like feeling tired after their treatment. Side effects depend on the area of your body being treated.

Conditions treated

IMRT is used to treat many kinds of cancer, including:

• Breast cancer
• Cervical cancer
• Lung cancer
• Prostate cancer
• Rectal cancer
• Stomach cancer
• Uterine cancer

Who performs this treatment?

A radiation oncology team designs and delivers IMRT. Team members include:

• A radiation oncologist, who directs all treatment steps
• A dosimetrist, who works with the radiation oncologist to design the radiation plan
• A medical physicist, who ensures all equipment operates properly to accurately deliver radiation
• A radiation therapist, who operates the machine during treatment

What happens before intensity-modulated radiation therapy?

IMRT requires careful design to make sure radiation is delivered effectively.

Your team will design treatment that’s best for your situation. The design process involves a treatment simulation. Your radiation care team will do the following:

1. They’ll do a CT scan to show the tumor location, size and shape. Your radiation therapist will work with your radiation oncologist to make sure you’re in a comfortable position for the CT scan and treatment.
2. They’ll create your individual radiation plan. The team does that by simulating treatment on a computer.
3. Your team will then place permanent tattoo dots after the simulated treatment. The dots look like freckles. They don’t wash off. Placing the dots allows your team to reposition you for treatment.
4. They might make molds to help hold areas of your body in place. For example, if you have brain or throat cancer, you need to hold your head and neck still during treatment. Your team may make a mold to help you do that.
5. After that, they’ll send the treatment design to the treatment machine for testing. Your treatment doesn’t start until the treatment team can make sure it’ll be safely delivered.

Your care team will also discuss any potential side effects before your treatment starts. Don’t hesitate to ask questions about potential side effects.

What happens during IMRT?

During treatment:

1. Your radiation therapist will help you get into position for treatment.
2. They’ll leave the treatment room to operate the machine. They’ll be able to view you on a monitor to make sure everything’s going smoothly. You’ll be able to communicate via a two-way intercom.
3. The machine will shift positions as it delivers radiation. It may make clicking and whirring sounds as it shifts. This is normal.

Treatment sessions last about 30 minutes. IMRT is an outpatient procedure, which means you can go home that same day.

How long will I need intensity-modulated radiation therapy?

Your treatment will depend on your situation. You’ll receive treatment over several days or weeks. Most people have daily treatments.

What are the potential benefits and risks of this treatment?

Intensity-modulated radiation therapy is a very precise treatment that’s less likely to damage healthy tissue while effectively treating several kinds of cancer. Though you may still experience side effects like fatigue and skin changes, this treatment typically causes fewer or less serious ones.

How long will it take me to feel better?

Many people feel better within a few weeks. Others may need a month or two to recover. IMRT affects people in different ways. Factors like the part of your body treated, the radiation dose and how often you have treatment may affect how long it takes you to recover.

Your team will check in with you during treatment. Be sure to share any symptoms that may develop during treatment.

Is there anything I can do to make this treatment easier on me?

The most important things are to take it easy after treatment and take good care of your skin. In general:

• Get your rest: Your body needs rest to heal after treatment. Remember to rest when you need to, not just when you can.
• Dress for comfort: If treatment affects your skin, wear loose-fitting, comfortable clothes that don’t irritate the treatment area. And be sure to wear light, long-sleeved tops and long pants when you’re outside on sunny days.
• Manage your side effects: Let your radiation team know about any issues you experience. They’ll work with you to reduce the issues that side effects can cause.

When should I call my healthcare provider?

Contact your radiation oncology team if you experience side effects that are more serious than you expect.