Needles are used in many surgical procedures such as drug delivery or needle biopsies. One of the key challenges when using needles in these interventions is the placement of the needle. Placement of the needle at the goal position will ensure proper execution of the surgical plan as well as avoid possible complications. This work explores tracking a needle with a piezoelectric sensor embedded at its tip with an ultrasound transducer and a mono-camera. While each of the ultrasound transducer and the mono-camera sensors are insufficient on their own, one can uniquely locate the position of the piezoelectric sensor by combining these two sources of sensor information together. The information from each sensor can be processed to determine a geometrical locus on which the piezoelectric sensor must lie. By spatially combining the geometrical loci from the two sensors using an ultrasound calibration process, one can uniquely determine the location of the piezoelectric sensor. An experiment in a water tank was conducted with the computed results compared to ground truth cartesian stage data. An in-plane accuracy measure resulted in errors of 0.63mm and 0.18mm. The relative accuracy measure had a minimum, maximum, mean, and standard deviation of 0.02mm, 2.15mm, 0.61mm, and 0.61mm respectively. Future work will focus on demonstrating this method in more realistic ex vivo scenarios and explore whether our listed assumptions hold.
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