Respect for Tissue Representation Using Photoelastic Stress Analysis for Endovascular Surgery Simulation - Microsurgery: Advances, Simulations, and Applications - page 139

The resulting set is shown in Fig. 4.14; for eliminating noise a
threshold of 200 mm was applied to the optical path length images,
this enhanced the borders of both urethane objects. Average stress
measurements were performed for the different values of P in the
ROI of the photoelasticity source images, first using the photoelastic
stress analysis and then by using equations (4.6, 4.28).

40 mmHg

100 mmHg 160 mmHg

50 mmHg 110 mmHg 170 mmHg

60 mmHg 120 mmHg 180 mmHg

70 mmHg 130 mmHg 189 mmHg

2560 2560

1920 1920

80 mmHg 140 mmHg

1280 1280

640 640

200

0

S 1 -S 2
(mmHg)

D (Mm)

90 mmHg 150 mmHg

Figure 4.14 Result image of the 16 samples. Below each set of two images,
the corresponding pressure is written. For each set, optical
path length D (left) and the corresponding photoelastic stress
analysis (right) are shown. A local maximum of stress appears
on the right side of the phantom as pressure increases. See also
Color Insert.

If r >> D , the wall thickness measurement inluence in the inal
result is almost the same for both methodologies; then the stress
measured using equations (4.6, 4.28) may be used as a reference for
the photoelastic error quantiication. The results for both methods
and their difference are plotted in Fig. 4.15. An average error of 3.9%