Soft Tissue Radiotherapy Real-Time Tracking Device Receives Approval

New US clearance expands the indications for which clinicians will be able to use a real-time tracking device for monitoring motion during radiotherapy treatments for cancer.

Varian Medical Systems (Palo Alto, CA, USA) has received 510(k) clearance from the US Food and Drug Administration (FDA) for a Calypso soft tissue Beacon transponder that can help enhance the precision of radiotherapy and radiosurgery treatments for cancer.

The new transponders, which are the size of a grain of rice, can be implanted within soft tissue throughout the body, with the exception of the lung. The Calypso GPS for the Body system can then continuously track and monitor the position of the transponders, so that the high energy treatment beams can be precisely aimed to minimize exposure of surrounding healthy tissues. An earlier version of the Calypso Beacon transponder was cleared for use specifically in the prostate and prostatic bed; the new clearance makes the system applicable for many other types of cancer.

Calypso Beacon transponders emit a nonionizing electromagnetic signal that is monitored in real time by the Calypso system, in order to guide treatment beams to precisely target tumors during radiotherapy and radiosurgery with medical linear accelerators, such as Varian’s Edge radiosurgery system.

“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,” said Andrea Morgan, Calypso product manager. “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 [SBRT], 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.”

“I have been using standard fiducial markers, particularly when treating tumors of the pancreas and liver,” said Mary Feng, MD, associate professor in the department of radiation oncology at the University of Michigan (Ann Arbor, USA). “It is essential that we know exactly where the tumor is at all times, and that we have a way of responding if the tumor moves during treatment. I’m excited about the prospect of using the Calypso tracking system treating in areas where it is very hard to see the tumor because of the lack of contrast with surrounding soft tissues.”

The new Calypso soft tissue Beacon transponders can only be used with the latest upgrade of the Varian Calypso system (version 3.0). Current Calypso Beacon transponders for the prostate are not suitable for the new soft tissue indication due to device and labeling differences. “Initial use of the new device is expected towards the end of the year,” said Corey Zankowski, vice president of product management at Varian. “We anticipate full commercial roll-out of the product sometime next year.”

Calypso soft tissue Beacon transponders are cleared for the US market only.

The Calypso system, including its Beacon transponders, was designed to align and/or monitor the patient’s position in relation to the radiation beam used for treatment. The Calypso system may also be used to regulate the treatment beam on Varian and Siemens Healthcare (Erlangen, Germany) radiation delivery systems by turning the beam on and off due to movement during treatment. Beacon transponders used as part of the system for monitoring patient motion are indicated for use on the skin surface for temporary external placement and for permanent implantation, specifically in the prostate and prostatic bed as well as in soft tissue.

Related Links:
Varian Medical Systems