| dc.description.abstract | This paper explores the possibility of employing a
non-invasive registration
technique using a high
resolution pulsed laser radar system as an intraopera
tive imaging system in computer assisted hip-joint
replacement surgery. The method involves acquiring 3D
laser surface points of the anatomical part to
be operated on intraoperatively, which are then
registered to a 3D surface model from preoperative
magnetic resonance imaging (MRI) using a surf
ace based registration program which utilizes an
Iterative Closest Point (ICP) algorithm. The descri
bed registration analysis was carried out with
respect to the hip-joint socket (acetabulum).
The performance of the laser radar system for the give
n task was tested in clinical environment where
it was used to scan an acetabulum of a female os
teoarthritic patient who was undergoing a total hip
replacement surgery at the Orthopaedic Clinic, Kassel
, Germany. The preoperative data of the affected
hip joint was acquired one day before the operati
on using a 1.5 Tesla high resolution MR imager
(MRT-Symphony Quantum, Siemens, Erlangen, German
y) at Clinical Centre, Kassel, Germany. In
order to capture clearly any remaining cartilage on the acetabulum, fat-suppressed T1-weighted 3D
gradient echo pulse sequence was applied in the acquisition of the MR images. Axial slices of the
affected hip joint were acquired with an in-pla
ne resolution of 1 mm × 1 mm and an inter-slice
thickness of 1mm. The size of the MR images w
as 256 × 256 × 87 voxels. Other acquisition parameter
settings were as follows: 50 degrees flip angle, 34
ms TR, 4.8 ms TE, and 250 mm field of view.
During the operation, the laser radar system was used
to obtain 3D points of the acetabulum, once part
of the pelvis was exposed. Laser points were
acquired from a distance of about 85 cm from the
scanning mirrors at a resolution of 1 mm in both X and Y axes of an XY coordinate system. The
scanned area was 40 mm × 40 mm and it was selected such that it covered the entire laser beam
accessible region of the acetabulum. | en |
