Intensity Modulated Radiotherapy (IMRT)

IMRT is an advanced form of 3D Conformal Radiotherapy that allows the physician to administer higher and varying doses of radiation to the tumor while sparing healthy surrounding tissue. It is one of the most precise forms of external beam radiation therapy available, and uses hundreds of tiny radiation beam-shaping devices to deliver a single dose of radiation.

In traditional radiation therapy treatment planning, the radiation oncologist first determines the number and angles of beams to be used for the treatment, then uses a computer to choose the appropriate doses of radiation that will be delivered from each beam. In contrast, IMRT uses what is known as “inverse treatment planning”. In inverse treatment planning, the radiation oncologist first selects the radiation doses to be administered to the tumor and surrounding tissue. After this initial determination, highly sophisticated computer software chooses the appropriate number and angles of beams that will safely deliver the specific doses of radiation that were prescribed by the physician.

The goal of IMRT is to increase to the dose of radiation to the areas that need it most while reducing the amount of radiation to the healthy tissue. The risk of certain side effects associated with 3D-CRT may also be reduced by using IMRT. It is commonly used to treat cancers of the head, neck, and prostate, as well as brain and spinal cord gliomas.