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Intensity Modulated Radiation Therapy (IMRT)

Last updated Feb. 6, 2019

U.S. Air Force photo/Staff Sgt. Liliana Moreno

Intensity Modulated Radiation Therapy (IMRT) is a procedure that uses computer-controlled linear accelerators, to deliver precise radiation to a malignant tumor.


Background Information:

What are the other Names for the Procedure?

  • IMRT (Intensity Modulated Radiation Therapy)

What is Intensity Modulated Radiation Therapy? (General Explanation)

  • Intensity Modulated Radiation Therapy (IMRT) is a procedure that uses computer-controlled linear accelerators, to deliver precise radiation to a malignant tumor
  • IMRT involves using multiple, small volumes of radiation beams, to control the intensity of the radiation beam and deliver it, precisely to the tumor
  • This procedure allows to minimize the radiation dose to the ‘normal’ surrounding tissues, thus reducing the side effects of the procedure
  • 3-dimensional CT (computed tomography) or MRI (magnetic resonance imaging) images are used to plan out the procedure, in order to precisely maximize radiation dose to the tumor

What part of the Body does the Procedure involve?

Depending upon the location of the malignancy, various parts of body are exposed to radiation therapy.

Why is the Intensity Modulated Radiation Therapy Performed?

  • Currently, Intensity Modulated Radiation Therapy procedure is used in the treatment of cancers of the central nervous system (CNS), prostate, head and neck region
  • They are also useful in treating pediatric malignancies and in some cases - sarcomas, breast, thyroid, GI, and gynecological malignancies

What is the Equipment used? (Description of Equipment)

  • Intensity Modulated Radiation Therapy uses a medical linear particle accelerator (LINAC) in order to generate radiation energy, by producing X-rays or high-energy electrons
  • The patient stays on the examination table, while the LINAC delivers radiation from various directions
  • In this procedure, the patients are in the room by themselves. The equipment may produce some noise as it functions, which is quite normal

What are the Recent Advances in the Procedure?

There have been no recent advances to replace the Intensity Modulated Radiation Therapy procedure.

What is the Cost of performing the Intensity Modulated Radiation Therapy?

The cost of Intensity Modulated Radiation Therapy procedure depends on a variety of factors, such as the type of your health insurance, annual deductibles, co-pay requirements, out-of-network and in-network of your healthcare providers and healthcare facilities. 

In many cases, an estimate may be provided before the procedure. The final amount depends upon the findings during the surgery/procedure and post-operative care that is necessary.

When do you need a Second Opinion, prior to the Procedure?

  • It is normal for a patient to feel uncomfortable and confused with a sudden inflow of information regarding Intensity Modulated Radiation Therapy procedure and what needs to be done
  • If the patient needs further reassurance or a second opinion, a physician will almost always assist in recommending another physician
  • Also, if the procedure involves multiple steps or has many alternatives, the patient may take a second opinion to understand and choose the best one. They can also choose to approach another physician independently

What are some Helpful Resources?

http://www.pamf.org/radonc/tech/imrt.html (accessed 2/22/2014)

http://www.radiologyinfo.org/en/info.cfm?pg=imrt (accessed 2/22/2014)

http://www.ncbi.nlm.nih.gov/pubmed/10631687 (accessed 2/22/2014)

Prior to Intensity Modulated Radiation Therapy:

How does the Intensity Modulated Radiation Therapy work?

The Intensity Modulated Radiation Therapy procedure works in the following manner:

  • The radiation therapy stops the cancer cells from dividing and growing further
  • It may also kill the cancer cells, thus shrinking the tumor or even eliminate it

How is the Intensity Modulated Radiation Therapy Performed?

  • Intensity Modulated Radiation Therapy sessions are generally scheduled, 5 days a week, for 5-6 weeks
  • The patient is suitably positioned on the treatment table
  • Skin marks may be used on the patient, or certain special devices made during the preparation sessions used, to keep the patient in certain positions
  • The radiation is applied, once the patient is in the exact required position

Where is the Procedure Performed?

IMRT is performed as an outpatient procedure, at a hospital.

Who Performs the Procedure?

A radiation therapist performs the whole procedure.

How long will the Procedure take?

The actual IMRT procedure may take about 15-30 minutes. However, there may be some waiting time involved, before and after the procedure.

Who interprets the Result?

A radiation oncologist interprets the result and progress of the Intensity Modulated Radiation Therapy procedure.

What Preparations are needed, prior to the Procedure?

The following preparations may be needed prior to an Intensity Modulated Radiation Therapy procedure:

  • Special treatment preparation sessions are required before starting the procedure. The radiation oncologist specifies the 3D shape of the tumor being treated, by using CT scanning, in order to develop an exact plan
  • Certain devices are necessary to be developed, before the procedure, which would help keep the patient in certain positions, during the procedure
  • Dosimetrist and medical physicist design IMRT beams, using CT scan information, for the procedure
  • MRI or PET (position emission tomography) scans may be needed during the treatment preparation. In some cases, contrast dyes may also be used, to find the exact location of the tumor being treated
  • In certain cases, radiological marker may be placed into the tumor, to determine accurate location of the tumor
  • The patient’s skin may also be marked with ink, to help deliver radiation by the equipment
  • The IMRT procedure is started, usually a week after treatment simulation/preparations
  • Depending on the procedure adopted, the patient may be asked for certain bowel or bladder preparations, before the preparation sessions

What is the Consent Process before the Procedure?

A physician will request your consent for Intensity Modulated Radiation Therapy procedure using an Informed Consent Form. 

Consent for the Procedure: A “consent” is your approval to undergo a procedure. A consent form is signed after the risks and benefits of the procedure, and alternative treatment options, are discussed. This process is called informed consent. 

You must sign the forms only after you are totally satisfied by the answers to your questions. In case of minors and individuals unable to personally give their consent, the individual’s legal guardian or next of kin, shall give their consent for the procedure.

What are the Benefits versus Risks, for this Procedure?

Following are the benefits of an Intensity Modulated Radiation Therapy procedure:

  • It can precisely target malignant tumors
  • This precision helps in minimizing side effects to normal healthy tissues
  • The side effects are much lesser, than caused by using normal radiation therapy

Following are the risks of an IMRT procedure:

  • There may be allergic reaction from the contrast dye used in preparation
  • The side effects may include secondary cancer, due to radiation effects

What are the Limitations of the Intensity Modulated Radiation Therapy?

Only certain specific malignancies and malignancies in certain locations can be treated, using the IMRT procedure.

What are some Questions for your Physician?

Some of the basic questions that you might ask your healthcare provider or physician are as follows:

  • What is an Intensity Modulated Radiation Therapy procedure?
  • Why is this procedure necessary? How will it help?
  • How soon should I get it done? Is it an emergency?
  • Who are the medical personnel involved in this procedure?
  • Where is the procedure performed?
  • What are the risks while performing the procedure?
  • What are the complications that might take place, during recovery?
  • What are the possible side effects from the procedure? How can I minimize these side effects?
  • How long will it take to recover? When can I resume normal work?
  • How many such procedures have you (the physician) performed?
  • Are there any lifestyle restrictions or modifications required, after the procedure is performed?
  • Are there any follow-up tests, periodic visits to the healthcare facility required, after the procedure?
  • Is there any medication that needs to be taken for life, after the procedure?
  • What are the costs involved?

During the Intensity Modulated Radiation Therapy:

What is to be expected during the Intensity Modulated Radiation Therapy?

The Intensity Modulated Radiation Therapy procedure in itself is painless. But, the patients may experience treatment-related side effects after the treatment.

What kind of Anesthesia is given, during the Procedure?

Since the procedure is a non-invasive procedure, no anesthesia is used during the procedure.

How much Blood will you lose, during the Procedure?

Since the procedure is a non-invasive procedure, no blood loss is involved during the procedure.

What are the possible Risks and Complications during the Intensity Modulated Radiation Therapy?

Rarely, there may be an allergic reaction from the contrast dye used in the preparations.

What Post-Operative Care is needed at the Healthcare Facility after the Intensity Modulated Radiation Therapy?

  • Generally, no significant post-operative care is needed at the healthcare facility
  • However, a short period of observation may be occasionally recommended by your healthcare provider

After the Intensity Modulated Radiation Therapy:

What is to be expected after the Intensity Modulated Radiation Therapy?

The following may be expected after an Intensity Modulated Radiation Therapy procedure:

  • The side effects of radiation therapy depends on which normal healthy tissues are radiated or affected, during the procedure
  • Some of early side effects include:
    • Hair loss
    • Fatigue or weakness
    • Eating problems
    • Digestion problems
    • Nausea, vomiting
    • Skin changes, such as redness, irritation, dryness, peeling
    • Urinary changes
  • Some of the later side effects include:
    • Hair loss
    • Formation of secondary cancer
    • Lung, kidney, spinal cord, brain, colon, rectal changes
    • Lymphedema

When do you need to call your Physician?

  • Generally, the patient’s progress and recovery is regularly followed by the healthcare provider, during and after the IMRT procedure
  • Patients should inform their physicians, if the side effects are very severe and unmanageable

What Post-Operative Care is needed at Home after the Intensity Modulated Radiation Therapy?

It is advised to take the recommended medications and precautions, in order to minimize the side effects of the Intensity Modulated Radiation Therapy procedure.

How long does it normally take to fully recover, from the Procedure?

The recovery time depends on the kind of side effects that develop. Early side effects usually disappear, within a few weeks after the procedure.

Additional Information:

What happens to tissue (if any), taken out during the Procedure?

An IMRT procedure does not involve the removal of any body tissue. 

When should you expect results from the pathologist regarding tissue taken out, during the Procedure?

Since no tissue is removed during the procedure, a pathologist does not get involved in the care of the patient. 

Who will you receive a Bill from, after the Intensity Modulated Radiation Therapy?

It is important to note that the number of bills that the patient may receive depends on the arrangement the healthcare facility has with the physician and other healthcare providers. 

Sometimes, the patient may get a single bill that includes the healthcare facility and the consultant physician charges. Sometimes, the patient might get multiple bills depending on the healthcare provider involved. For instance, the patient may get a bill from:

  • The hospital, where the procedure is performed
  • Healthcare providers, physicians, who are involved in the process

The patient is advised to inquire and confirm the type of billing, before the Intensity Modulated Radiation Therapy procedure is performed.

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Feb. 22, 2014
Last updated: Feb. 6, 2019