Table 2.

Tissue parameters used to calculate OPs of the five major tissue compartments.

Tissue	Variable tissue parameters	Fixed tissue parameters
Scalp	$\mathrm{tHB}$, ${\mathrm{StO}}_2$, $C_{\text{melanin}}$, $A$, $K$	$C_{\text{water}}=75\%$, $C_{\text{collagen}}=2\%$
Skull	$\mathrm{t}\mathrm{H}\mathrm{B}$, $\mathrm{S}\mathrm{t}{\mathrm{O}}_2$, $A$, $K$
CSF	None	Literature reported values
GM	tHB, ${\mathrm{StO}}_2$, $A$, $K$	$C_{\text{water}}=75\%$
WM	None	${\mu }_{a,\mathrm{WM}}=\frac{{\mu }_{a,\mathrm{GM}}}{2}$, ${\mu }_{s,\mathrm{WM}}^{\prime }=3\times {\mu }_{S,\mathrm{GM}}^{\prime }$