Bezier-Like Functions For Constructing Craniofacial Fractures
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Date
2016-09
Authors
Abdul Majeed
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Abstract
Craniofacial deformity or injury secondary to trauma is a challenge to diagnose
and treat, both for a radiologist and a treating surgeon due to its complex anatomi-cal
location in the human body. The construction of craniofacial fracture parts en-ables an
interested researcher to propose a model of the defect or deformity and to facilitate the
treating physician in providing the best possible management protocol to his/her
patient. In the literature, different techniques such as using mirroring, reference model
and Computer Aided Design (CAD) / Computer Aided Manufacturing (CAM)
technology are employed for a construction of craniofacial fractures. This thesis proposes
a construction of missing parts of craniofacial fracture using Bezier-like rational
curves with different continuities namely C1;C2;GC1 and GC2. Higher order continuity
means smoother common joint between adjacent curve segments. Curve fitting is
achieved using the least squares method to optimize intermediate control points and
free parameters are calculated using Genetic Algorithm (GA). In order to validate the
proposed method, 2D images of various objects such as a bear, a vase and an Arabic
letter 8Dal′ are constructed. The proposed method is applied to reconstruct the boundary
curve of a full slice. Mathematical morphology is used to determine the boundary
of the chosen skull. Inner and outer curves of a fractured part are constructed in 2D
form of the Computed Tomography (CT) scanned data which are in Digital Imaging
and Communications in Medicine (DICOM) format and in 2D format, respectively.
The constructed parts are then converted back to DICOM format. Finally, results obtained
from this method using several Bezier-like functions are compared to each other.
For the construction to be useful and user-friendly to a treating doctor or a surgeon, a
Graphical User Interface (GUI) has also been developed. The aim of this GUI is to minimize
the procedure and the time to help this doctor or surgeon treating his/her patient
with craniofacial fracture without having to understand the algorithm or mathematics
behind its construction. To construct the 3D craniofacial fracture, a 2D contour is
converted to a 3D form by forming together corresponding equidistant z-components.
Then, a contour blending method and bi-cubic rational Bezier-like functions are applied
in order to construct the fractured part in 3D. The proposed method used in this
thesis is based on DICOM data only and does not require any other technique such as
mirror imaging or reference skull and there is no need to take the average thickness of
skull bone. Using the proposed method, the constructed fractured implant is custommade
for any patient. In this thesis, CT scanned data for five real cases of craniofacial
fractures are obtained from the Hospital Universiti Sains Malaysia (HUSM) to test the
methods applicability in real life situation.
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Keywords
A construction of missing parts of craniofacial fracture using Bezier-like rational curves , with different continuities namely C1;C2;GC1 and GC2.