Dynamic Targeting™ IGRT using real-time imaging techniques helps doctors locate and target moving tumors with unprecedented accuracy.

At the Karolinska Institute in Stockholm, Sweden, Jan-Olov Carlsson lies on a treatment couch under a medical linear accelerator. He is ready to receive his daily dose of radiation for a prostate cancer diagnosed in early 2004. An X-ray system on robotic arms slides into place on either side of his body, then rotates around him, taking images to pinpoint the tumor’s exact location. In a control room, clinicians monitor computers that match the images with Carlsson’s treatment plan to see if the tumor has shifted. It has. Within seconds, the coordinates needed to put Carlsson’s tumor into perfect alignment with the radiation beam are calculated. Then, with the push of a button, Carlsson’s therapists adjust the couch and position him for treatment.

Sixty-year-old Carlsson is one of more than a dozen patients this day at the Karolinska Institute, where Varian Medical Systems’ On-Board Imager™ device is being used to deliver image-guided radiation therapy (IGRT). IGRT helps doctors locate and target tumors with unprecedented speed and precision.

“IGRT is a significant incremental improvement in accuracy and our ability to deliver more radiation safely,” according to Munther Ajlouni, MD, an early adopter of IGRT and radiation oncology director at the Henry Ford Health System in Detroit, Michigan. Ajlouni and other doctors expect that IGRT will be an important weapon for combating many types of cancer.

“The On-Board Imager device verifies that you’re hitting the target and avoiding surrounding critical structures,” says Timothy Fox, PhD, director of medical physics at the Emory University School of Medicine’s Department of Radiation Oncology in Atlanta, Georgia.

If accuracy increases as much as expected, radiotherapy guided by daily X-ray imaging could begin to be used to treat small metastatic tumors and lesions that currently require surgery or chemotherapy. “We think IGRT will allow us to tackle different stages and types of tumors that we haven’t treated before,” says Fox.

In 2004, Varian’s On-Board Imager technology was not only installed at Karolinska, Henry Ford, and Emory, but also at the Hirslanden Klinik in Aarau, Switzerland; M.D. Anderson Cancer Center in Houston, Texas; Memorial Sloan-Kettering Cancer Center in New York; Piedmont Hospital in Atlanta, Georgia; Stanford University Medical Center in Palo Alto, California; and other major cancer treatment centers.

Doctors at these centers are using Varian’s new technology to help treat prostate and brain tumors, and they are planning or beginning to use it with gynecological tumors as well as cancers of the pancreas and the head and neck. All these applications share the same goal: Deliver enough radiation to the tumor to eliminate it, while minimizing the amount of healthy tissue exposed to the beam.

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