Fig. 1From: Audiovisual biofeedback breathing guidance for lung cancer patients receiving radiotherapy: a multi-institutional phase II randomised clinical trialAV biofeedback system (left). Display goggles and real-time position management (RPM) marker block on the abdomen shown. The visual display (right), as seen by the patient, of the AV biofeedback guiding interface shows the waveguide (white curve) and a marker position (grey marker) in real timeBack to article page