3-D FREEHAND ULTRASOUND CALIBRATION USING A TISSUE-MIMICKING PHANTOM WITH PARALLEL WIRES

article describes a method used to calibrate 3-D freehand ultrasound systems based on phantoms with parallel wires forming two perpendicular planes, such as the usual general-purpose commercial phantoms. In our algorithm, the phantom pose is co-optimized with the calibration to avoid the need to precisely track the phantom. We provide a geometrical analysis to explain the proposed acquisition protocol. Finally, we give an estimate of the system accuracy and precision based on measurements acquired on an independent test phantom. We obtained error norms of 1.6 mm up to 6 cm of depth and 3.5 mm between 6 and 14 cm of depth, in total average. In conclusion, it is possible to calibrate ultrasound tracked-probe systems with a reasonable accuracy based on a general-purpose phantom. Contrarily to most calibration methods that imply the construction of the phantom, the present algorithm is based on a standard phantom geometry that is commercially available. (E-mail: sandra. marcadent@epfl.ch) (c) 2022 World Federation for Ultrasound in Medicine & Biology. All rights reserved.

Automated summary

The article presents a method for calibrating 3-D freehand ultrasound systems using phantoms with parallel wires to form perpendicular planes. The algorithm co-optimizes the phantom pose and calibration, eliminating the need for precise phantom tracking. A geometrical analysis is provided to explain the proposed acquisition protocol. The system accuracy and precision are evaluated based on measurements acquired on an independent test phantom, with error norms of 1.6 mm at depths up to 6 cm and 3.5 mm between 6 and 14 cm. The study concludes that ultrasound tracked-probe systems can be calibrated with reasonable accuracy using a commercially available general-purpose phantom.