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SHG in Tumors
β
varies between –0.5 and 1, and I
SHGpar
and I
SHGperp
correspond to the intensities of the SHG signals
polarized parallel and perpendicular to the laser polarization, respectively. A similar PA parameter
has also been expressed as PA = (I
SHGpar
– I
SHGperp
)/(I
SHGpar
+ I
SHGperp
), where PA varies between 0 and 1
[63,64]. In both cases,
β
or PA = 0 corresponds to less ordered collagen, and
β
or PA = 1 corresponds
to more ordered collagen [46,51,60,63,64]. ird, we can obtain the helical pitch angle of collagen
(see the Appendix, Figure A.2, and description) [36,37,39,65]. Finally, we can obtain the “tilt” angle
of individual collagen triple helices relative to the collagen bril axis (see the Appendix, Figure A.3,
and descript ...