Intensity Modulated Radiation Therapy (IMRT)

IMRT is one of a number of leading-edge cancer therapies offered at Martin O’Neil Cancer Center.

Radiation therapy seeks to stop cancer cells from growing and dividing by damaging or killing them. The more precisely radiation therapy can be delivered, the greater the likelihood that treatment will kill all of the cancer cells, shrinking or eliminating the tumor, and the fewer side effects patients will experience.

IMRT is an advanced radiation therapy that uses 3-D scans of your body along with precision computer guidance to “paint” the radiation beams to exactly match the size, shape and location of the tumor. Small beams are directed from multiple directions, with each producing customized beam intensity and shape that conforms the radiation field to the size and shape of the tumor. The responsive computer control adjusts the shape of the beam throughout the treatment to ensure precision delivery of the radiation. These adjustments ensure each part of the tumor receives the full dose of radiation, while minimizing exposure to surrounding healthy tissue.

IMRT can be used to non-invasively treat most solid tumors, cancerous and noncancerous, but is most commonly used to treat cancers of the prostate, head and neck, and central nervous system. It has also been used to treat breast, thyroid, lung, gastrointestinal and gynecological cancers and certain types of sarcomas.

IMRT uses computer-controlled medical linear accelerators (LINAC) to deliver precisely-calibrated photon or proton beams to the exact location of the tumor. Because the radiation is largely confined to the tumor’s outlines, higher doses of radiation can be used, as a much smaller amount reaches healthy tissue than with other technologies. This increases the effectiveness of treatment, while lowering side effects.

Your radiation oncologist will map the exact location and shape of your tumor, and determine the total dose and number of treatments (fractions) your cancer will require, depending on the type, size, and density of your tumor. A radiation physicist and dosimetrist will program this information into the LINAC’s computer to set up your treatments. A radiation therapist will help you get into the correct position and ensure your comfort. In most cases, you will have a custom mold to help you remain in the exact position required for the 15 or so minutes of each treatment session. Intravenous contrast material or radio-dense markers may be used to help pinpoint the treatment beams. Typically, treatment consists of five daily sessions each week for five to eight weeks.