Versatile robotic probe calibration for position tracking in ultrasound imaging

Within the field of ultrasound-guided procedures, there are a number of
methods for ultrasound probe calibration. While these methods are usually
developed for a specific probe, they are in principle easily adapted to other
probes. In practice, however, the adaptation often proves tedious and this
is impractical in a research setting, where new probes are tested regularly.
Therefore, we developed a method which can be applied to a large variety
of probes without adaptation. The method used a robot arm to move a
plastic sphere submerged in water through the ultrasound image plane,
providing a slow and precise movement. The sphere was then segmented
from the recorded ultrasound images using a MATLAB programme
and the calibration matrix was computed based on this segmentation
in combination with tracking information. The method was tested on
three very different probes demonstrating both great versatility and high
accuracy.