Introduction
Image-Guided Radiation Therapy (IGRT) is a type of external beam radiation therapy for cancer that adjusts for the location (or position) of a cancer tumor throughout treatment. Cancer tumors may move, change size, and change shape throughout the course of treatment. IGRT uses advanced positioning technology to localize the tumor before each treatment. Based on the daily measurements, the radiation is configured before each treatment. In turn, the radiation is more precise, effective, and results in fewer side effects.
IGRT is used to reduce and destroy cancer cells from an external source of radiation. Radiation from high-energy beams disrupts the growth of cancer cells. Radiated cancer cells are not able to repair themselves or grow. Radiation damages all cells, both healthy and cancerous, in the exposed area. IGRT spares as many healthy cells as possible because it directs radiation to only a specific area, the cancer tumor.
IGRT uses advanced daily imaging techniques to track and record the location of a tumor throughout treatment. This is advantageous for several reasons. The radiation is continually adjusted and customized to the tumor size and shape. IGRT can deliver radiation from about any angle. Its versatility helps to spare as much healthy tissue as possible, while delivering a precise high-dose radiation treatment. There are various types of IGRT machines. IGRT may be used to help treat a variety of cancers including brain, spine, prostate, thoracic, lung, breast, and head and neck cancers. It may also be used to treat arteriovenous malformations in the brain.
Treatment
Prior to your treatment, you will meet with your doctor for a consultation and treatment simulation. During the simulation, your treatment area will be measured and marked. This ensures that the radiation is delivered to the same area with each treatment. Markings may be made on your skin with bright temporary paint or small tattoos. Special blocks or shields may be fabricated to keep the radiation from contacting healthy tissue and shape the radiation beam for treatment.
Headrests, molds, casts, and other devices may be created to keep your body in position during treatment. Sophisticated IGRT technology can adjust for small movements caused by breathing during treatment or internal processes, such as digestion. It is common to have a computed tomography (CT) scan during simulation to help prepare the overall treatment plan. A CT scan is a painless imaging test that simply requires that you remain motionless.
In the majority of cases, IGRT is an outpatient treatment. IGRT treatments are usually delivered five days a week for three to ten weeks. Radiation treatments may be received once or more each day. The amount of radiation that you receive depends on many factors, such as the size, shape, type, and location of your cancer tumor.
Prior to each treatment, imaging tests will depict the size, shape, and location of your tumor. Your doctor will use the information to prescribe your radiation each day. It may take several minutes to position your body for treatment. IGRT is painless. You will have a microphone to communicate with the radiation therapist at all times. In most cases, people can return to work or resume their regular activities after a treatment.