Biomedical Engineering Reference
In-Depth Information
the components of
O
P
MORG
). The irst three parameters represent
the position, and the others are used to express the orientation by
using quaternion's conventions. We need to convert the quaternion
information into transformation matrix form [26], and calculate the
transformation matrix
O
T
M
. From the previous assumption of sensors
alignment, we can deine
M
T
I
with
¨
100 0
010 0
001
000 1
¸
©
¹
©
¹
M
T
©
(7.15)
¹
d
©
¹
©
¹
ª
º
The parameter d stands for the distance between the magnetic
tracker and the IVUS emitter (the component in
Z
M
axis for
M
P
IORG
),
which can be measured directly after assembly. After obtaining those
parameters, we can obtain the transformation matrix
O
T
I
and then
convert the image coordinate to physical coordinate according to Eq.
7.13.
Y
I
IVUS Coordinate
System
Y
O
Global Coordinate
System
O
I
X
I
Z
I
O
O
Y
M
X
O
Z
O
M
P
IORG
O
P
MORG
O
M
X
M
Z
M
Magnetic Sensor
Coordinate System
Figure 7.26
Kinematic relation between the frame of reference of Aurora
emitter and IVUS probe.
7.5.5
3D Imaging and Rendering
Figure 7.24 shows result images examples for contour extraction
process and location of catheter center. Then the contour coordinates
are expressed in homogeneous coordinates to be used in the
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