PRO-TIP: Phantom for RObust automatic ultrasound calibration by TIP detection

TL;DR

This paper introduces a fully automatic ultrasound probe calibration method using a custom 3D-printed phantom with neural network-based tip detection, offering robustness, ease of use, and generalization across different probes.

Contribution

A novel phantom design and an automated calibration algorithm that do not require tracking targets, improving usability and applicability across various ultrasound devices.

Findings

Achieves calibration accuracy comparable to domain experts.

Generalizes well across different ultrasound probes and vendors.

Provides open-source design and code for reproducibility.

Abstract

We propose a novel method to automatically calibrate tracked ultrasound probes. To this end we design a custom phantom consisting of nine cones with different heights. The tips are used as key points to be matched between multiple sweeps. We extract them using a convolutional neural network to segment the cones in every ultrasound frame and then track them across the sweep. The calibration is robustly estimated using RANSAC and later refined employing image based techniques. Our phantom can be 3D-printed and offers many advantages over state-of-the-art methods. The phantom design and algorithm code are freely available online. Since our phantom does not require a tracking target on itself, ease of use is improved over currently used techniques. The fully automatic method generalizes to new probes and different vendors, as shown in our experiments. Our approach produces results comparable to calibrations obtained by a domain expert.