Anchored Beacon Transponder Guides Lung Cancer Radiotherapy

A novel beacon transponder detects even slight movements of a tumor, helping clinicians deliver lung stereotactic body radiotherapy (SBRT) more precisely.

The Varian Medical Systems (Varian; Palo Alto, CA, USA) Calypso Anchored Beacon Transponder is designed for implantation in small airways within or near the tumor target. Anchoring is provides via five expandable nitinol legs that provide stable fixation, preventing the transponder from moving. Once in place, the transponder emits continuous, non-ionizing electromagnetic signals that are tracked in real-time and used to keep a SBRT beam on target. The Anchored Beacon transponder is intended for use with the Varian TrueBeam, Edge, and Clinac C-series medical linear accelerators.


The direct internal tracking eliminates the need for external surrogates to track tumor motion in real time, so that high-dose lung SBRT can be delivered with reduced margins between the clinical target volume (CTV) and the planning target volume (PTV). The implantation process itself is straightforward, similar to a lung biopsy, using a pre-loaded, single use delivery catheter designed for interventional pulmonologists and general pulmonologists with advanced bronchoscopy training. The Calypso Anchored Beacon Transponder has been approved by the U.S. Food and Drug Administration (FDA).

“The 510(k) clearance of the Anchored Beacon Transponder expands the application of the Calypso system platform,” said Ed Vertatschitsch, vice president of global portfolio solutions at Varian. “Using the Calypso system and Anchored Beacon transponder, clinicians can deliver dose to lung tumors with increased confidence and accuracy.”

SBRT is emerging as an attractive option for treating cancers in the lung, head and neck, prostate, liver and other disease sites, with the objective of increasing local control of the target lesion while limiting damage to nearby critical structures and normal tissue. Requirements include precise localization of the target lesion in the treatment planning process; accounting for tumor motion due to respiration or other changes in the body; highly conformal dose distribution to the target volume, including a steep dose gradient to minimize radiation to surrounding healthy tissue; and image-guidance at the time of dose delivery for verification and adjustment of the target localization.