Respect for Tissue Representation Using Photoelastic Stress Analysis for Endovascular Surgery Simulation - Microsurgery: Advances, Simulations, and Applications - page 138

Vasculature
Model

Pressure
Sensor

Syringe

Figure 4.12 Fluid closed loop for pressure variation and measurement
inside the blood vessel model.

The average green value of ROI I GP for a pressure P is normalized
using

I -

-

I

GP GMin

I (4.29)

GNP

I I

GMax GMin

I GMin and I GMax are the minimum and maximum values of green,
respectively, and are obtained from

40 4 F

I I (4.30)

GMin G IG

200 20 F (4.31)
where F IG 40 and F IG 200+ are the standard deviation of I G 40 and I G 200+ .
A sample of source images of photoelasticity and transmittance
measurements is shown in Fig. 4.13. We deduced from I G 40 that I GMin
is 23.32 and from I G 200+ that I GMax is 53.86. For this experiment the
value of M G = 510 nm and was obtained as described in previous
sections. The optical path length was calculated by applying equation
(4.6) to the transmittance images set.

I I

GMax G IG

Variable
Thickness
Membrane

Phantom

Birefringence Higher near
the axis of the phantom

a) b)

Figure 4.13 Source image example when P = 189 mmHg for: (a) optical
path length calculation (b) and retardation measurement.