An automatic algorithm for distinguishing optical navigation markers used during surgery

Abstract

To improve the safety, accuracy and effectiveness of

surgery, while also reducing surgical trauma, three-dimensional

spatial positioning of the surgical instruments can be achieved

through the accuracy of integration of medical imaging to

guide their operation during surgery. Therefore, prior to

surgery, registration is required to establish the relationship

between the actual positioning of the surgical instruments

and their imaged position. The accuracy of such registration

directly determines the precision of navigation. Taking into

account the shortcomings and deficiencies of the current

fiducial marker registration methods, this paper proposes an

automatic fiducial marker extraction and matching algorithm.

In order to facilitate automatic recognition and extraction of

the fiducial markers the authors of this paper designed fiducial

marker with Computed Tomography (CT) values and shapes

that provide recognizable characteristics which help to meet

the demands of the positioning requirements. The extraction

of such fiducial markers can be easily automated, significantly

reducing the difficulty in developing an extraction algorithm.

After fiducial marker extraction the registration algorithm and

the Iterative Closest Point (ICP) algorithm can be combined

to achieve matching between the fiducial marker and point set

model of the fiducial marker. According to the matching results

indicating the positional relationship between the each fiducial

marker and its retroreflective sphere, the center coordinate

of the retroreflective sphere in the image can be acquired,

hence providing an easy way to undertake registration of the

different spatial representations of the patient.