The first two liver cancer patients in Europe were treated with stereotactic body radiotherapy (SBRT) using Varian’s Calypso "GPS for the Body" transponders. Aarhus University Hospital in Denmark used the transponders to track tumor motion while treating the 77-year-old man and 76-year-old woman.
The three electromagnetic transponders are implanted at the edge of the tumors during an outpatient procedure. During SBRT, the transponders ensure that the tumor is in the right position while the patient is exhaling and corrects the patient’s position if the tumor moves.
In the past, physicians would have to treat a larger margin around the tumor because they didn’t know the tumor’s precise position every day. But since they can now monitor its position in real time, they can reduce the treatment margin and spare more healthy tissue.
"Calypso is a real-time monitoring device that provides additional evidence that the dose is being delivered where it should be, which is even more important in higher-dose treatments like radiosurgery,” Per Poulsen, associate professor responsible for motion management tools, said in a statement.
Going forward, Aarhus University Hospital is looking to track tumor motion with the treatment beam, which will provide real-time adaptation to both respiration and tumor movement, and make the procedure faster and smoother. They are also going to explore its use in proton therapy treatments.