Biomedical Engineering Reference
In-Depth Information
FIGURE 15.7
Model-updated images of a pig brain experiencing a 1 cm piston-induced displacement of
the temporal lobe: (a) volumetric segmented brain surface, (b) coronal cross-sectional image,
and (c) axial cross-sectional image. Notice the visible collapsing of ventricular space as well
as the compression of white matter tracks in the deformed image volume.
(Figure 15.9a). Once inserted, brain model nodes nearest the retractor are
moved onto the defining surface and duplicated to create two coincident
nodal positions that will represent independent degrees of freedom once the
blade begins to move (Figure 15.9b). Movement of the blade (Figure 15.9c)
occurs by applying boundary conditions, either fixed displacements or normal
stresses in the direction of retraction, for one set of the coincident nodes defining
the blade geometry while the second set of nodes become stress free and able to
move according to the equations of consolidation. Once the boundary condi-
tions are applied and the calculations completed, the tissue deformation map
