Fibre-Optic Photoacoustic Beacon and 2D Sparse Sensor Array for 3D Tracking of Needles

Accurate knowledge of the needle tip location during percutaneous procedures such as liver and breast biopsies, cancer treatment, drug delivery, and fetal blood transfusion would reduce adverse events, misdiagnoses and failed procedures. We have developed a novel trackable ultrasonic needle and 3D tracking system for such percutaneous medical needle procedures. The location of the needle tip is annotated onto the anatomical ultrasound images being used to guide the procedure, with the quantitative distance of the needle tip from the ultrasound imaging plane also visualised. The device works by transmitting pulses of ultrasound from our proprietary low-cost fibre-optic trackable needle which are detected by a sparse sensor array located on the patient's skin. This novel solution allows truly simultaneous 3D tracking and imaging with any ultrasound or other imaging system, in contrast to existing ultrasonic solutions which either provide only 2D tracking or must reduce the imaging frame rate to avoid interference. Tracking accuracy was assessed in water to depths of 14 cm and up to 3 cm from the ultrasound imaging plane: the spatial-average bias between tracked and true positions was 0.37 mm and the spatial-average repeatability was 1.2 mm.