Cancer Centre Tests Transponder Treatment for Liver Cancer Patients

Two liver cancer patients in Denmark have become the first in Europe and only the second and third in the world, to be treated with stereotactic body radiotherapy (SBRT) using Calypso® ‘GPS for the Body’ transponders from Varian Medical Systems. The 77-year-old man and a woman, aged 76, both with metastases in the liver, were treated in three sessions over six days at Aarhus University Hospital.

“Our experience so far is that tracking tumours with Calypso transponders may help make a significant difference in liver SBRT treatments,” said Morten Høyer, professor of clinical oncology at Aarhus. “In the past, we would have to apply a more generous treatment margin around the tumor because of uncertainties regarding the precise tumour position from day to day. Calypso allows us to monitor the treatment real-time and reduce the treatment margin, meaning less healthy tissue is treated.”

Per Poulsen, associate professor responsible for motion management tools, added, “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. These implanted markers are a very good representation of what is happening real-time.”

With application of gated treatments the transponders could also be controlled between inhalation and exhalation cycles, providing improved precision by overcoming motion caused by breathing.

“The Calypso transponders help ensure the tumour is in the planned treatment position during exhale and provides easy online correction of the patient position to counteract tumour drift,” said medical physicist Esben Worm. 

“As a next step we hope to use Calypso transponders to track tumor motion with the treatment beam, which will allow fast and smooth treatment delivery with real-time adaptation to both respiration and target movement,” said Dr. Poulsen. “We also hope to explore their use in proton therapy treatments.”

The National Proton Therapy Centre in Denmark, which will be located at Aarhus University Hospital will be equipped with Varian’s ProBeam™ proton therapy system.