Linear accelerators are used to safely and painlessly deliver precise radiation doses to a tumor while minimizing the dose to surrounding normal tissue.
Your radiation oncologist can determine whether IMRT is the most appropriate treatment for you.
Intensity-Modulated Radiation Therapy (IMRT)
Intensity Modulated Radiation Therapy (IMRT) Intensity-modulated radiation therapy (IMRT) is an advanced mode of high-precision radiotherapy that utilizes computer-controlled linear accelerato
rs to deliver precise radiation doses to a malignant tumor. IMRT allows for the radiation dose to conform more precisely to the three-dimensional (3-D) shape of the tumor by modulating or controlling the intensity of the radiation beam. This is done by dividing this beam into thousands of small pencil sized beamlets. IMRT also allows higher radiation doses while minimizing the dose to surrounding normal critical structures. Treatment is carefully planned by using 3-D computed tomography (CT) images of the patient in conjunction with computerized dose calculations to determine the dose intensity pattern that will best conform to the tumor shape. Typically, combinations of several intensity-modulated fields coming from different beam directions produce the desired treatment plan.
Because the ratio of normal tissue dose to tumor dose is reduced to a minimum with the IMRT approach, higher and more effective radiation doses can safely be delivered to tumors with fewer side effects compared with conventional radiotherapy techniques. IMRT also has the potential to reduce treatment toxicity, even when doses are not increased. IMRT does require longer daily treatment times, however with Volumetric Modulated Arc Therapy (VMAT) (a newer way of delivering IMRT) treatment times have been reduced substantially.
Side Effects
As with other external beam radiation therapy treatments, there is no pain expected during the actual treatments with IMRT. However, the machine can be stopped if you experience discomfort due to the treatment position or positioning devices. As treatment progresses, some patients may experience treatment-related side effects. The nature of the side effects depend on the normal tissue structures being irradiated. The radiation oncologist and the nurse will discuss and try to help you with any side effects. Side effects of radiation treatment include problems that occur as a result of the treatment itself as well as from radiation damage to healthy cells in the treatment area. The number and severity of side effects you experience will depend on the type of radiation and dosage you receive and the part of your body being treated. You should talk to your doctor and nurse about any side effects you experience so they can help you manage them. Radiation therapy can cause early and late side effects. Early side effects occur during or immediately after treatment and are typically gone within a few weeks. Common early side effects of radiation therapy include tiredness or fatigue and skin problems. Skin in the treatment area may become more sensitive, red, irritated, or swollen. Other skin changes include dryness, itching, peeling and blistering.
Early side effects may include:
Hair loss in the treatment area
Mouth problems and difficulty swallowing
Eating and digestion problems
Diarrhea
Nausea and vomiting
Headaches
Soreness and swelling in the treatment area
Urinary and bladder changes
Long term side effects, which are rare, include:
Brain changes
Spinal cord changes
Lung changes
Kidney changes
Colon and rectal changes
Infertility
Joint changes
Lymphedema
Mouth changes
Secondary cancer
There is a slight risk of developing cancer from radiation therapy. Following radiation treatment for cancer, you should be checked on a regular basis by your radiation oncologist for recurring and new cancers.
Using techniques such as IMRT, radiation oncologists are maximizing the cancer-destroying capabilities of radiation treatment while minimizing its effect on healthy tissues and organs and the side effects of the treatment itself.
