13
The accuracy verification tool (AVT)
Accuracy verification must be implemented by the integra-
tor. They can optionnaly purchase the required software and
hardware at Atracsys.
The operator performing accuracy verification must be cor-
rectly trained.
The accuracy verification method is a procedure which checks that the fusionTrack device is able to per-
form accurate measurements in the whole working volume. A failure of this test indicates that the fusionTrack
device must not be used and must be returned to Atracsys.
13.1
General concept
The principle of this test is to verify that a given rigid body keeps its fixed geometry wherever the measure-
ment is performed. For a
marker
, the distance between two
fiducials
is determined and cannot change,
independently of the
marker
’s position in the working volume. The test consists of moving a
marker
in the
whole working volume, the best way to ensure repeatability being to define 3D positions at which the
marker
should stay for a while (e.g. for 500 frames) and monitor the
marker
’s registration error as well as the dis-
tances between the
marker
’s
fiducials
. If the used
marker
is accuratly calibrated, it may be enough to look
at the width of the distribution of the registration error. The integrator must specify an upper bound on this
width, above which the test is considered to fail. In general, monitoring the distance between two
fiducials
of the
marker
is a suitable way to perform this test: again the width of the distribution of the measured length
must not be larger than a threshold specified by the integrator.
13.2
Running the procedure
This procedure is not part of the usual running of the
navigation system
: it must be run by a trained techni-
cian, on a regular basis. For instance the integrator can choose to run this procedure once every week or
every 5 surgeries, whatever comes first.
13.3
The accuracy verification tool from Atracsys
Atracsys offers as an aditional accessory a rigid body designed to perform accuracy verification on the
fusionTrack. Along with this rigid body, Atracsys provides the required software to perform the capture of
data and the accuracy analysis. Please contact the Atracsys after sale service for further information (See
Section 1.6).
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