## 3 Results and Discussion
As shown in Table 7, the correlation coefficient values of each kind of bulk tissue samples for the parameters group (\(\theta_{e}\), \(\phi_{qr}\)) are all equal to 0.99, while those for (\(\theta_{c}\), \(\phi_{2434}\)), (\(\theta_{e}\), \(\phi_{4243}\)) range between 0.58 and 0.97. We can also see that the data points of all tissue samples are evenly distributed along a straight line in Figure 6e. Particularly, Table 7 and Figure 6 also confirm that the parameters (\(\theta_{c}\), \(\phi_{qr}\)) show no statistically significant differences with the \(p>0.05\). Therefore, when measuring linear birefringence orientation of bulk tissue samples using backscattering polarimetry, both the parameters \(\phi_{qr}\) and \(\theta_{e}\) can provide quantitatively similar information, and \(\phi_{qr}\) can be calculated faster. In summary, the results shown in Sections 3.5 and 3.6 demonstrate that among the available MMT linear birefringence orientation parameters, \(\phi_{qr}\) shows the best accordance with the MMPD parameter \(\theta_{e}\). The parameters \(\phi_{2434}\) and \(\phi_{4243}\) only contain partial linear birefringence orientation information of tissue samples with layered fibrous structures. Thus, when taking the elements m\({}_{24}\), m\({}_{34}\), m\({}_{42}\), and m\({}_{43}\) from both the fourth column and fourth row of the Mueller matrix into account, the modified parameter \(\phi_{qr}\) can well present the linear birefringence orientation information more thoroughly. Quantitative Comparison of Depolarization MMPD and MMT Parameters for Transmission Imaging of Thin Tissue Samples  
In previous studies, both the MMT parameter \(1-b\) shown in Equation (14) and MMPD parameter \(\Delta\) shown in Equation (4) have been used to represent the depolarization property of tissue samples [5]. However, there would be a deviation between these two parameters when the medium contains a circular depolarization property encoded in the element m\({}_{44}\), which the parameter 1-\(b\) does not take into account. To more accurately represent the overall depolarization of tissues, we proposed a modified parameter \(1-b_{m}\) as Equation (18) shows. The comparison results of the MMT and MMPD depolarization parameters for 7 kinds of thin tissue samples are shown in Table 8 and Figure 7. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{3}{*}{**Type**} & \multirow{3}{*}{**Tissues**} & \multicolumn{6}{c}{**Linear Birefringence Fast Axis Orientation**} \\ \cline{3-8}  & & & \(R^{2}\) & & \(p\) & \\ \cline{3-8}  & & \(\theta_{e}\)\(\rightarrow\)\(\phi_{2434}\) & \(\theta_{e}\)\(\rightarrow\)\(\phi_{243}\) & \(\theta_{e}\)\(\rightarrow\)\(\phi_{qr}\) & \(\theta_{e}\)\(\rightarrow\)\(\phi_{2434}\) & \(\theta_{e}\)\(\rightarrow\)\(\phi_{4243}\) & \(\theta_{e}\)\(\rightarrow\)\(\phi_{qr}\) \\ \hline \multirow{6}{*}{Backward} & breast & 0.97 & 0.97 & 0.99 & \(>\)0.05 & \(>\)0.05 & \(>\)0.05 \\  & rat-skin & 0.58 & 0.82 & 0.99 & \(>\)0.05 & \(>\)0.05 & \(>\)0.05 \\ \cline{1-1}  & porcine-intestine & 0.75 & 0.97 & 0.99 & \(>\)0.05 & \(>\)0.05 & \(>\)0.05 \\ \cline{1-1}  & porcine-stomach & 0.96 & 0.97 & 0.99 & \(>\)0.05 & \(>\)0.05 & \(>\)0.05 \\ \cline{1-1}  & porcine-liver & 0.91 & 0.96 & 0.99 & \(>\)0.05 & \(>\)0.05 & \(>\)0.05 \\ \cline{1-1}  & Total & 0.87 & 0.95 & 0.99 & \(>\)0.05 & \(>\)0.05 & \(>\)0.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Correlation and statistical analysis comparison results between backward measured MMT and MMPD linear birefringence orientation parameters for each kind of bulk tissue samples. Figure 6: Comparison of linear birefringence fast axis orientation MMT and MMPD parameters of bulk tissue samples. (**a**) Variance of linear birefringence orientation MMPD parameters \(\theta_{e}\) plotted against its counterpart MMT parameter \(\phi_{2434}\) for correlation analysis with all five kinds of bulk tissue samples.