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What Is Intensity Modulated Radiation Therapy?

L. Whitaker
L. Whitaker

Intensity modulated radiation therapy, sometimes also called IMRT for short, is a type of radiotherapy using computer-guided beams of radiation doses that closely conform to the shape of an individual tumor. This kind of radiation therapy is said to be more controlled and precise than previous radiotherapy techniques, which has the advantage of lower overall toxicity for surrounding healthy tissues. In general, intensity modulated radiation therapy is used for individuals with cancerous tumors in certain areas of the body, including the prostate, head, neck, and nervous system. This procedure can also be utilized in some cases for the treatment of cancer in the breast, lung, thyroid, female reproductive system, or gastrointestinal system.

In the process of intensity modulated radiation therapy, photon energy is created and delivered by a large device called a medical linear accelerator, or LINAC. The radiation is aimed in patterns that have been established based on diagnostic imaging, such as computerized tomography, or CT, scans. A custom-designed dose of radiation is designed to provide the maximum appropriate dose for an individual tumor while also keeping toxic side effects to a minimum. Intensity modulated radiation therapy is said to require less trial and error to obtain an optimal therapeutic dose than other types of radiotherapy procedures.

A linear accelerator can be used for intensity modulated radiation therapy.
A linear accelerator can be used for intensity modulated radiation therapy.

The patient receiving IMRT treatment will typically need to attend short treatment sessions five days per week for up to eight weeks. An individual's radiation treatment plan is generally created based on factors such as the patient's current level of health and the type, size, and location of the cancerous tumor being targeted. Radiation beams will be aimed at specific locations marked on the patient's skin in accordance with the treatment plan. In some cases, computer imaging devices could be used during radiotherapy to monitor correct positioning. Patients generally do not experience any discomfort during the treatment.

As with any type of radiation therapy, IMRT can have side effects. Some effects can happen quickly, such as fatigue, hair loss, nausea, headaches, and skin dryness. These side effects typically disappear within a few days or weeks of the end of treatment. Rarely, more serious and permanent side effects can occur many months after treatment, such as organ damage or secondary tumors. In many cases, the use of IMRT instead of traditional radiotherapy can minimize short-acting side effects.

Radiation therapy is a common treatment for many types of cancer. Intensity modulated radiation therapy and other types of radiotherapy work by ceasing the division and proliferation of cancer cells, which causes a tumor to stop growing in size or slow its growth rate. Radiation therapy often results in the outright destruction of cancer cells, leading to the shrinkage or total elimination of a tumor.

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    • A linear accelerator can be used for intensity modulated radiation therapy.
      By: Alex Tihonov
      A linear accelerator can be used for intensity modulated radiation therapy.