Biomedical Engineering Reference
In-Depth Information
Fig. 3.21 a
Reconstruction of 3D air spaces separated by tissues from region of interest.
b
Enlarge-
ment of a small alveolated air section isolated from the centre of region of interest. (Image from
Tsuda et al. 2008)
3.5
Summary
The reconstruction of the respiratory airways begins with obtaining the relevant data
for the application. For realistic airway models, medical imaging techniques using the
latest technology are needed especially for regions where there are micro structures
like the acinus region. However the use of SRXTM scanners and its data are not as
widely available as those from CT and MRI. Regardless the scanned images are 2D
contiguous slices that are separated by a known interval distance. The reconstruction
of this data from 2D to 3D requires extraction of the region of interest in what is
known as the segmentation process. A number of algorithms have been developed
by researchers and biomedical scientists which can be accessed through either open-
source/free software or commercial software. Access to the algorithms is available
either through a graphical user interface or command line text. After segmentation,
the extracted region typically needs to be 'cleaned' for any noise or artificial regions
that are not needed. Sometimes the model may need further processing in CAD
software. An important step before moving to a CFD mesh model is to ensure that
the segmented model has a water-tight surface. Although the reconstruction process
is dependent on segmentation techniques, there are alternatives and these alternatives
are also provided for the different regions of the respiratory airway.
This chapter aimed to bring the reader up to speed with techniques of recon-
struction that cross over into different disciplines including biomedical imaging,
manufacturing/reverse engineering, and CAD/drafting fields. The content presented
is an overview of some theory and its application and is certainly not an exhaustive
description of what exists for the disciplines mentioned. However it is hoped that the
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