Intensity Modulated Radiation Therapy
(IMRT)En Español (Spanish Version)
Intensity modulated radiation therapy (IMRT) is a treatment of cancer. It uses radiation beams of different intensities to deliver appropriate cytotoxic doses to the tumor while reducing the dose to nearby uninvolved tissue.
Radiation therapy uses radiation to kill cancer cells and shrink tumors. Some normal cells will be damaged with radiation. The goal of radiation therapy is to kill as many cancer cells as possible, while limiting damage to healthy cells.
Radiation of Tumor
© 2008 Nucleus Medical Art, Inc.
Parts of the Body Involved
The parts involved will depend on the location of the cancer being targeted.
Reasons for Procedure
Radiation therapy works to destroy or shrink the tumor to eliminate or prevent the spread of cancer. It can also be used to relieve symptoms caused by the tumor (eg, pain, bleeding). IMRT is currently being used to treat the following types of cancers:
Risk Factors for Complications During the Procedure
A risk factor is something that increases your chance of having complications during your procedure. Risk factors for complications during IMRT include:
- Previous radiation therapy
- Pregnancy: radiation during pregnancy can harm the developing fetus
What to Expect
Prior to Procedure
Planning for IMRT is more complex than planning for conventional radiation therapy, and generally takes 2-5 days. Planning may include:
- Physical exam
Coming in one or more times for imaging tests to identify exactly where the radiation beams will be focused; imaging tests used may include:
- X-ray—a test that uses radiation to take a picture of structures inside the body
- CT scan—a type of x-ray that uses a computer to make pictures of structures inside the body
- MRI scan—a test that uses magnetic waves to make pictures of structures inside the body
- PET scan—a test that uses a special camera to view structures inside the body after a radioactive solution is injected into a vein
- CT/PET scan—a simultaneous fusion of both studies; provides increased accuracy than either study alone
- Marking the locations of the skin where the radiation will be focused to guide the therapist
- Being fitted for a localization device (eg, mask, body frame), which can help target accuracy
- Using ultrasound or implanted markers to track the position of the tumor
Anesthesia is not needed.
Description of the Procedure
Using the marks made on your skin as a guide, the radiation therapist positions you on the treatment table. Films or ultrasound may be used to check the accuracy of the treatment set up. Then the therapist leaves the room to control the movements of the radiation machine, which generally involves targeting the tumor from several different angles and using various intensities of the radiation beam directed specifically to the tumor. The treatment delivers radiation in a three-dimensional manner, to conform as closely as possible to the shape of the tumor. (The healthy tissue receives smaller doses of radiation than the tumor.)
You will be asked to remain still during the radiation treatment, and you may breathe normally. Although you will not generally feel or sense anything during treatment, the machine can be stopped if you feel sick or uncomfortable. The therapists will be monitoring you on a TV camera, and will be able to hear you speak should you need to.
You will be able to leave and resume your normal daily activities. Receiving IMRT does not make you radioactive, and you do not need to avoid being around other people because of the treatment.
How Long Will It Take?
Each session will take 15-30 minutes. Patients are typically scheduled for IMRT five days per week for 4-8 weeks.
Will It Hurt?
IMRT is generally associated with fewer side effects than conventional radiation therapy. Side effects vary from person to person, depending on the location of your cancer. Some people experience no side effects at all. General side effects of radiation therapy may include:
- Skin changes
- Hair loss
- Loss of appetite
- Specific side effects associated with the area of the body being treated
Although uncomfortable, the side effects associated with radiation therapy are usually not serious. They can be controlled with medication and diet. Your radiation oncologist can explain the side effects you are likely to experience and help determine the best strategies of managing them.
Average Hospital Stay
IMRT is typically performed on an outpatient basis.
During treatment, your doctor will want to see you at least once a week. You may have blood tests to check the levels of red blood cells, white blood cells, and platelets. Although, this is not routinely done as much anymore.
After your treatment is completed, you will come in for regular visits to monitor for side effects and healing, and check for signs of recurrent disease. You may require further testing, medication, or rehabilitative treatment.
The outcome varies depending on the size and location of your tumor. Ideally, radiation therapy will result in shrinkage or complete elimination of the cancer. Compared with conventional radiation therapy, IMRT can shorten the overall treatment time. However, IMRT can also increase the duration time because it allows greater doses to be given safely than conventional radiation therapy; this may also improve the success of the treatment.
Call Your Doctor If Any of the Following Occurs
Discuss any side effects you are experiencing with your doctor. He or she can prescribe medications or recommend strategies to manage them. It is especially important to call your doctor if any of the following occur:
- Persistent pain
- New or unusual lumps, bumps, or swelling
- Nausea, diarrhea , vomiting, or loss of appetite
- Unexplained weight loss
- A persistent fever or cough
- Unusual rashes, bruising, or bleeding
- Other symptoms you are concerned about
American Cancer Society
National Cancer Institute
BC Cancer Agency
BC Health Guide, British Columbia Ministry of Health
External radiation therapy. American Cancer Society website. Available at: http://www.cancer.org/docroot/ETO/content/ETO_1_7x_external_radiation_therapy.asp . Accessed November 15, 2005.
IMRT. International Radiosurgery Support Association website. Available at: http://www.irsa.org/imrt.html . Accessed November 15, 2005.
Intensity-modulated radiation therapy (IMRT). American College of Radiology and Radiological Society of North America website. Available at: http://www.radiologyinfo.org/content/therapy/imrt.htm . Accessed November 15, 2005.
Radiation therapy and you. National Cancer Institute website. Available at: http://www.cancer.gov/cancertopics/radiation-therapy-and-you/ . Accessed November 15, 2005.
Radiation therapy for cancer: questions and answers. National Cancer Institute website. Available at: http://www.cancer.gov/cancertopics/factsheet/Therapy/radiation . Accessed November 15, 2005.
Last reviewed March 2008 by Igor Puzanov, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright © 2011 EBSCO Publishing All rights reserved.