Image-guided radiotherapy (IGRT)

Tumors can sometimes move during radiation therapy treatment (usually due to patient breathing) and between treatments. At Advocate Health Care, we use Dynamic Targeting® IGRT – or image-guided radiotherapy – from Varian Medical Systems to track the position of tumors in real-time and deliver precise treatment.

How it works

Tissues, organs and many tumors are not rigidly fixed in one position; they move around inside the body due to natural processes. For this reason, they are not always in the exact same position each time a patient is positioned for treatment. In addition, tumors can move several centimeters due to a patient's normal respiratory cycle.

For Dynamic Targeting IGRT, the linear accelerator, or treatment machine, is outfitted with a number of advanced imaging devices that provide your doctor with images to help guide the treatment.

An X-ray system mounted on a robotic arm is rotated around the body to gather images that pinpoint a tumor's exact location just prior to treatment. These images are then compared with reference images (MRI, CT or other kinds of scans) in order to determine if the tumor is where it is expected to be, or off by some margin. Sophisticated software programs calculate how to move the patient so that the tumor is directly in the center of the treatment beam.

This technology allows for "respiratory gating", which turns the radiation beam on and off as the patient breathes normally, so that it is delivered only when the tumor is in the correct position, directly in the path of the beam. This is useful for treating lung cancer and other tumors in the chest or abdomen affecting by breathing.

Benefits of IGRT

• Over 60% of cancer patients receive some form of radiotherapy as part of their treatment. This is because radiotherapy is very effective at controlling many forms of cancer by destroying cancer cells’ ability to reproduce.
• Through more precise targeting, dosage levels can be increased and the area of treatment can be reduced – so tumors get more powerful radiation and healthy surrounding tissues get very little.
• Imaging and tracking technologies with IGRT enable our team to treat tumors even if they are close to vital structures like the spinal column, heart or lungs. This can mean substantially fewer side effects and a much better quality of life.