The company claims that the new clearance expands the indications for which clinicians will be able to use the Calypso real-time tracking device for monitoring motion during radiotherapy treatments for cancer.

Implanted within soft tissue throughout the body, with the exception of the lung, the new rice grain sized transponders emit a non-ionizing electromagnetic signal that is tracked and monitored in real time by the Calypso GPS for the Body system to guide treatment beams to precisely target tumors during radiotherapy and radiosurgery with medical linear accelerators.

Calypso product manager Andrea Morgan said: "With the new transponder, clinicians can use the Calypso system most places they would have used standard fiducial markers, such as gold seeds, to localize a targeted tumor, but with the added benefit of continuous tumor position tracking throughout treatment delivery.

"Other types of fiducial markers have to be localized using X-rays, which add more ionizing radiation to the process.

"We’re pleased to be able to make the system available to clinicians who want to use it more broadly, not just for conventional radiotherapy but for some of the newer approaches, like stereotactic body radiotherapy, which involves delivering higher radiation doses very quickly.

"For treatments like that, accurate targeting is essential, and the new Calypso transponders have an important role to play."

Varian Medical Systems had received approval for the earlier version of the Calypso Beacon transponder for use specifically in the prostate and prostatic bed. The new clearance makes the system applicable for many other types of cancer.

The new Calypso soft tissue Beacon transponders can only be used with the latest upgrade of the Varian Calypso system (version 3.0).