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Intensity-Modulated Radiation Therapy (IMRT)
Intensity-Modulated Radiation Therapy, or IMRT, is a form of radiotherapy that utilizes computer-controlled x-ray accelerators to deliver precise radiation doses to treat cancer. By controlling the dose of the radiation in accordance with a three-dimensional image of the tumor, IMRT is able to effectively treat a tumor while minimizing radiation exposure to the non-cancerous surrounding tissues. The goal of IMRT is the same as that of other forms of radiation treatment: to kill cancer cells and shrink or eliminate tumors (1).
Because the exposure to normal tissue 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 (1). Delivering the radiation in such a precision fashion requires high-speed computers, diagnostic imaging devices, patient-positioning devices, and a variety of complex machinery designed to focus or block the radiation beam in accordance with the 3-D image of the tumor (2).
Currently, IMRT is primarily used to treat cancers of the prostate, head and neck, breast, thyroid and lung, as well as in gynecologic, liver and brain tumors and lymphomas and sarcomas. IMRT is also beneficial for treating pediatric cancers (1).
IMRT is performed by a specially trained team, which typically consists of a radiation oncologist, medical radiation physicist, dosimetrist (an individual who specializes in determining appropriate doses of radiation), radiation therapist and radiation therapy nurse. The treatment is administered with a medical linear accelerator (1).
IMRT is an aggressive therapy that requires multiple treatment sessions. Typically, patients are scheduled for IMRT sessions five days a week for six to ten weeks. As in other forms of radiation treatment, the IRMT sessions themselves are painless; however, 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 (1).
- "Intensity-Modulated Radiation Therapy (IMRT)." From RadiologyInfo.org. Available: http://www.radiologyinfo.org/en/info.cfm?pg=IMRT&bhcp=1 (Accessed July 19, 2007).
- "How IMRT Works." From the website of the Mayo Foundation for Medical Education and Research. Available: http://www.mayoclinic.org/imrt/howitworks.html (Accessed July 19, 2007).