Image Guided Radiotherapy (IGRT)

IGRT is a leading-edge radiation therapy option offered by Martin O’Neil Cancer Center.

Radiation therapy seeks to stop cancer cells from growing and dividing by damaging or killing them. This always requires a careful balancing act between delivering the most radiation to the cancer cells, while protecting nearby healthy tissues. Faster-growing cancer cells are more vulnerable to radiation damage than healthy cells causing them to be killed while surrounding cells recover from the damage. The fewer healthy cells exposed to radiation, however, the lower the risk of side effects. The human body is constantly in motion, even at rest. No matter how still a patient attempts to remain during treatment, body processes create continuous motion, making it difficult to keep radiation focused with pinpoint accuracy throughout treatment. For some cancers, the simple act of respiration causes significant movement of the treatment area, requiring radiation dosages to be lowered to reduce damage to surrounding healthy tissue.

IGRT insures pinpoint radiation delivery by combining a variety of high-resolution 2-D, 3-D, and 4-D imaging techniques with motion visualization software and automated beam repositioning, into a single protocol. This imaging technology is integrated into the treatment session, allowing precise delivery regardless of motion or changes to the tumor during or between sessions. IGRT is frequently used for tumors and cancers located very close to sensitive organs, and tumors that are more likely to be affected by movement. IGRT is particularly well suited to compensate for respiratory motion.


  • More precise visualization of the tumor’s size, shape, and location
  • Pinpoint accuracy of radiation delivery
  • More of the radiation reaches the target cells, increasing effectiveness
  • The possibility of safely using higher treatment doses
  • Shorter treatment schedules
  • Less radiation reaches healthy tissues, reducing side effects
  • IGRT is often used as a companion to IMRT.