Dynamic Targeting IGRT

What is Dynamic Targeting IGRT?

Dynamic Targeting IGRT improves radiation treatment delivery accuracy in its ability to perform daily imaging of the tumor.

Dynamic Targeting IGRT uses images taken just before treatment to pinpoint any changes in the location of the tumor. These changes may be caused as a reaction to the therapy, weight loss, organ movement due to bowel changes or simply from breathing.

University Hospital uses Varian Medical Systems' On Board Imager mounted on robotic arms to perform daily CT, fluoroscopic or high quality x-ray images. These images are computer matched to the original planning images to see if the tumor has shifted. Within seconds calculations determine tiny movements needed to align the tumor perfectly with the radiation beam. Any corrections are automatically made by adjusting the position of the patient on the treatment couch before treatment. These changes may be as small as 1-2 millimeters and that is exactly the level of precision we aim for. IGRT allows our experienced team to deliver the safest, most accurate radiation therapy possible.

IGRT Positioning

Why is Dynamic Targeting IGRT so important?

In recent years advances in technology have allowed us to deliver very sophisticated forms of computer assisted radiation therapy, namely IMRT (Intensity Modulated Radiation Therapy). The main limitation to this powerful treatment is tumor movement. Tumors can shift within the body from day to day and depending on their location, can move several centimeters while breathing during treatment. Doctors have had to account for this movement by making the radiation beam larger, including healthy tissue as a result. The amount of radiation that could be delivered was limited therefore to avoid complications to the healthy tissue in the treatment area.

Because the tumor location can be imaged on a daily basis Dynamic Targeting IGRT provides the capability of increasing the dose delivered to the tumor over time while reducing the dose to the surrounding structures. IGRT means that a smaller radiation beam can be used to spare healthy tissue and allows the team to deliver a higher, lethal dose of radiation to the tumor.

Dynamic Targeting IGRT with its daily imaging and adjustments allows precision delivered radiation therapy like never before.

How does Dynamic Targeting IGRT work?

How an On-Board Imager Works Diagram

The linear accelerator produces the radiation that is used to deliver radiation therapy treatment. It is equipped with an x-ray tube and flat-panel image detector mounted on robotic arms. Low dose x-rays are used to create high quality CT, fluoroscopic or digital x-rays.

These images are instantly seen on the display monitor and matched to the planning images. Coordinates are then calculated directing millimeter movements needed to precisely align the tumor with the radiation beam. The team can automatically reposition the patient with ease. The entire process takes approximately 3 -5 minutes .

Benefits of IGRT

  • IGRT offers new hope to patients with difficult to treat tumors such as those next to a vital organ or other hard to reach area.
  • IGRT helps limit the amount of radiation delivered to healthy tissue around the tumor because tighter margins can be prescribed.
  • IGRT can allow the physician to deliver higher doses of radiation to the tumor because of these tighter margins.
  • IGRT can reduce side effects and improve the quality of life for patients.