ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

4.RESULTS
To test the developed system an ATOM ® MAX Dental & Diagnostic Head Phantom,
model 711-HN from CIRS, USA was used. The phantom is built of epoxy resin and is
constructed of proprietary tissue equivalent materials. The phantom contains anatomical
structures such as bones, brain, larynx, trachea, sinus, nasal cavities and teeth [3]. The
phantom is scanned by the producer and CT data was provided.
A 3D models of phantom coating as well as bone were generated. The accuracy of the
registration procedure was investigated.
Fig. 6. Test of registration procedure accuracy
For the registration procedure external landmarks of phantom coating were used: two
points of eyebrows, tip of the nose, two points of nasal base. Four points were applied
for registration - to calculate matching matrix, and two another points (A and B) were
applied to calculate Target Registration Error (TRE) (see tab. 1). Target Registration
Error is a distance between a point measured using navigated pointer, related to the
intraoperative reference frame coordinate system (IO) transformed to DICOM
coordinate system, and the real position of the point in DICOM coordinate system.
Tab. 1. Results of test of registration using surface points
x
[mm]
y
[mm]
z
[mm]
TRE
[mm]
Point A in IO coordinate system
394,08 180,33 159,77
Point A transformed to DICOM coordinate system 132,61 28,76 -92,19 7,74
Point A in DICOM coordinate system 140,27 29,75 -91,78
Point B in IO coordinate system
425,48 197,10 163,13
Point B transformed to DICOM coordinate system 97,53 35,07 -89,35 4,46
Point B in DICOM coordinate system 100,40 33,89 -92,56