MRT involves varying (or modulating) the intensity of the radiation being used as the therapy for cancer. It is a new form of radiation therapy that uses computer-generated images to plan and then deliver more tightly focused radiation beams to cancerous tumors than is possible with conventional radiotherapy. With this capability, physicians can deliver a precise radiation dose that conforms to the shape of the tumor, while significantly reducing the amount of radiation to surrounding healthy tissues. Consequently, the technique can increase the rate of tumor control while significantly reducing side effects.
MRT uses computer-generated images to plan and then deliver tightly focused radiation beams to cancerous tumors. Physicians use it to exquisitely "paint" the tumor with a precise radiation beam that conforms as closely as possible to the shape of the tumor.
IMRT can be used to treat tumors that might have been considered untreatable in the past due to close proximity of vital organs and structures. Treating such tumors requires tremendous accuracy. In the case of head and neck tumors, IMRT allows radiation to be delivered in a way that minimizes exposure of the spinal cord, optic nerve, salivary glands, or other important structures. In the case of prostate cancer, exposure or the nearby bladder or rectum can be minimized. IMRT is being used to treat tumors in the brain, breast, head and neck, liver, lung, nasopharynx, pancreas, prostate, and uterus.
A powerful computer program optimizes a treatment plan based on a physician's dose instructions, and information about the tumor size, shape, and location in the body. A medical linear accelerator, equipped with a special device called a multileaf collimator that shapes the radiation beam, delivers the radiation in accordance with the treatment plan. The equipment can be rotated around the patient to send radiation beams from the most favorable angles for giving the tumor a high dose while preserving important healthy tissues.