Intensity-modulated radiation therapy (IMRT)

Intensity-modulation radiation therapy, also called IMRT, is a type of 3D conformal radiation therapy used to visualize and plan where radiation is delivered to treat cancer. What sets IMRT apart from other radiation treatments is its ability to deliver radiation doses of different intensities to different parts of a tumor. It can modulate, or vary, the intensity of radiation beams across a tumor so more precise treatment can be tailored to specific parts of a tumor. For example, lower intensity beams can be delivered to areas of tumors near healthy tissue to limit their radiation exposure, while higher intensity beams can be used where cancer cells are highly concentrated.

IMRT can effectively keep cancer cells from dividing and growing. It can slow or, in many cases, stop tumor growth. Using precise imaging tools, it maps the exact shape and size of a tumor so radiation beams can be delivered in varying intensities on the same tumor for the most targeted and powerful treatment.

Penn Medicine has a multidisciplinary team of radiation oncologists, medical physicists, dosimetrists (who specialize in radiation dosing levels), and radiation technicians who plan for and deliver intensity-modulation radiation therapy. Our board-certified radiation specialists have years of experience in providing individualized radiation treatment options for the best possible outcomes. 

Intensity-modulation radiation therapy is used to treat various forms of cancer. It’s a particularly useful treatment option for highly sensitive or delicate areas of the body, such as the brain or spinal cord, because of its ability to deliver different radiation doses to different parts of a tumor. Compared with other radiation treatments, it can have fewer side effects.

IMRT can be used to treat the following types of cancer at Penn Medicine:

• Bone cancer
• Brain cancer
• Breast cancer
• Gastrointestinal cancer such as stomach cancer and gastrointestinal stromal tumors
• Gynecologic cancers such as ovarian, cervical, uterine, vulvar, vaginal, fallopian tube, and gestational trophoblastic disease
• Head and neck cancer
• Lung cancer
• Prostate cancer
• Spinal cord cancer

Typically, there are a few steps involved in receiving intensity-modulation radiation treatment. Some steps are required to plan the treatment, while others are required to deliver the external radiation beams. Your care team will describe the different steps needed and answer any questions you have about treatment.

First, you’ll have imaging tests that help visualize the size and shape of the tumor. This may include CT, MRI, or PET scans. Your care team will use these images to plan for, or simulate, the actual treatment. They’ll program these images into a linear accelerator machine, which guides the delivery of high-intensity x-ray beams. During this simulation process, you may receive markings, or tattoos, on your skin to designate the treatment area. Your radiation oncology team may also place you on the table where treatment will take place to identify the best position for you to receive treatment.

After the simulation phase is complete, you’ll be ready to start having regular IMRT radiation treatments. This is when external radiation beams are delivered in varying intensities to different parts of the tumor. During treatment, you’ll stay still on the treatment table as a linear accelerator machine moves around you at different angles to deliver radiation beams.

Your care team will advise you on a schedule for your treatments. Each treatment typically lasts up to 30 minutes, though times may vary. You will not have any pain during radiation treatment.

People can experience a variety of symptoms as they recover from IMRT radiation treatment. Symptoms are often dependent on the size, shape, and location of the tumor, and the intensity of each dose. Some symptoms are short term, lasting only a few weeks, while other symptoms may last longer.

Your care team will advise you on ways to handle any issues you have during recovery. They’ll often recommend a combination of approaches that may include the following:

• Wear clothes that are comfortable and do not constrain the treatment area.
• Treat your skin with extra care, avoiding any harsh ingredients that may be aggravating.
• If you are outside in the sun, wear protective clothing around the skin that received radiation.
• Do not apply ice or heat directly on the treatment area unless a doctor instructs you to do so.
• Get plenty of rest and fluids and eat a healthy diet.

Penn Medicine’s radiation oncology team are experts who use the latest radiation therapies to treat cancer, including IMRT. We create precise measurements to develop radiation treatment plans that match the needs of every patient, with the goal of sparing healthy tissue while eliminating cancer cells.

Our radiation therapies are delivered by doctors who are leaders in their field. This means patients have early access to the latest research and clinical advances. As a high-volume radiation therapy center, we perform procedures that may be done only occasionally at other locations. Studies have shown that centers performing higher volumes of procedures have better patient outcomes.

Our physicians, nurses, and clinical staff focus on creating a supportive environment for patients who receive radiation therapy. Our care team understands what it’s like to be on the patient side of the table. They listen and tailor recommendations and care plans to every patient’s individual needs to deliver the most effective outcomes with compassion.