By providing real-time, continuous tumor position information, Calypso® 17G soft tissue Beacon® transponder can help enhance precision of radiotherapy and radiosurgery treatments for cancer. Each FDA 510(k)-cleared and CE-marked unit emits non-ionizing electromagnetic signal. Excluding lungs, transponders can be implanted within soft tissue throughout body. Calypso system tracks signal, precisely guiding treatment beams to target tumors during treatment with medical linear accelerators.