Intensity-modulated radiation therapy (IMRT)

Intensity-modulated radiation therapy (IMRT) is one of the most advanced three-dimensional radiation treatment plan, employing thousands of tiny beams from various beam angles to target a tumor. These tiny beams are created by a highly sophisticated computer program that separates cancer tissue from normal tissue and assigns different radiation beam intensities to the tiny areas as directed by the doctors.

The radiation intensity of the beams is modulated or controlled by a multi-leaf collimator(MLC), which is a system of movable leaves. The leaves mold to the shape of the tumor, blocking out harmful radiation to surrounding normal organs and tissues. Each leaf can move independently to create tiny beamlets of radiation that specifically target a tumor using sophisticated dose calculation methods.

This treatment method allows high doses to the tumor while surrounding normal tissue is significantly spared. Less radiation exposure to normal tissues means fewer complications for the patients. IMRT is ideal for tumors that are close to vital structures like the spinal cord, heart, and eyes, brain, etc.,


Before the Procedure

You will attend a simulation, or "sim," session prior to treatment. The goal of simulation is to collect the information required by your radiation oncology team to design your treatment. During simulation:

  • You will have a CT scan to see the tumor. You may also have an MRI or a PET scan.
  • You will be tattooed with dots to help you align your body with the LINAC(linear accelerator). The marks are approximately the size of a freckle. They are drawn on in some cases, but they must remain throughout the treatment.
  • Your radiation oncology team will position you during simulation so that the machine can deliver energy beams at the precise angles required to target the tumor.
  • You may be fitted with special accessories such as custom mold to keep your body in position during the treatment.
  • Your radiation oncology team will use the simulation data to create energy beams with varying intensities to target the tumor.

During the Procedure

The dosing schedule varies depending on the type of cancer. Treatment is usually given in short (5 to 15 minutes) sessions spread out over several days to weeks. Majority of the people receive IMRT from Monday through Friday. Depending on your cancer, treatment could last for several weeks.

During treatment:

  • You'll be positioned exactly as you were during simulation. Any molds used to keep the treatment area perfectly still will be assisted by your radiation technologist.
  • Your radiation technologist will leave the room to operate the LINAC machine. They'll be able to see you on a monitor from another room to ensure everything is running smoothly. A two-way intercom will allow you to communicate if needed.
  • As it delivers multiple energy beams of radiation to the treatment fields, the machine will shift positions. As it shifts, it may make clicking and whirring sounds.

Intensity-modulated radiation therapy is a painless procedure. You won’t feel the radiation during treatment.

After the Procedure

Doctor will probably see you at regular intervals to see how well the treatment worked. They will also keep an eye on things and assist with any side effects. You will almost certainly need to see your doctor for follow-up care for at least a couple of years after your treatment.


  • Standard radiation therapy causes side effects such as abdominal pain, diarrhea, and mouth and throat ulcers by affecting both cancerous and normal surrounding tissue. People who undergo IMRT have fewer treatment-related side effects.
  • IMRT also has the potential for higher cure rates.


  • Damage to healthy tissue and organs:Radiation therapy targets and kills cancer cells by using high-powered energy beams. The beams can also harm healthy nearby cells. The side effects may vary depending on the area of the body being treated.
  • Fatigue: It is a common side effect of radiation therapy that typically begins a few weeks after treatment and worsens as treatment progresses. Fatigue can last for several weeks to months after treatment is completed.
  • Skin reactions: The treated area of skin may become hyperpigmented, dry, and tender. These reactions typically subside a few weeks after treatment, but some skin changes may be permanent.
  • Hair loss: Radiation therapy to the head or neck can cause hair loss. The hair usually grows back after treatment, but it may be a different color or texture.
  • Nausea and vomiting: They are common side effects of radiation therapy. They usually start during the first week of treatment and go away after a few days. Symptomatic treatment will be given to the patient to relieve nausea and vomitings.
  • Weight loss: Weight loss is a known side effect which can be prevented or reduced by appropriate diet management and care at home.

IMRT Care at Medicover

Medicover Hospital operates a full-fledged facility providing integrated cancer care that is powered by clinical excellence, world-class technology as well as international standards to India. The hospital has a team of doctors who are experienced in treating every cancer specialty with modalities such as radiation oncology, medical oncology, and surgical oncology. Medicover Hospitals follows a comprehensive approach to prevent and treat cancer through its dedicated team to optimize patient care. The goal of our cancer center is early detection, personalized treatment, and care delivered by a multidisciplinary team of oncologists through comprehensive cancer consultation. Our approach to treatment focuses on preserving the diseased organ as much as possible without compromising the patient's safety, resulting in a faster recovery time, minimal or no disfigurement, and a return to normal life as soon as possible.

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Frequently Asked Questions

1. What cancers are treated with IMRT?

IMRT is most commonly used to treat prostate cancer, head and neck cancers, lung cancer, brain cancer, gastrointestinal cancers, and breast cancer due to the proximity of these tumors to vital organs and tissues in the body.

2. Do tumors grow back after radiation?

Normal cells near the cancer can also be damaged by radiation, but most of them recover and resume normal function. They may reappear in future, if radiotherapy does not kill all of the cancer cells.

3. How long do IMRT sessions generally last?

The majority of treatment sessions last between 10 and 30 minutes.

4. How many treatments do I need?

Multiple sessions are required for IMRT. IMRT sessions are typically scheduled five days a week for several weeks. The total sessions of treatment is determined by a variety of factors, including the type of cancer, size, and location of the tumor.