Table 2.

The stopping power ratio (SPR) sensitivity ratio factors R_L and R_H calculated for all three x-ray beam pairs. The ratio factors were calculated based on the error propagation, as shown in section 2.5. The values were averaged of all tissue types within each tissue group.

Energy Pairs	Tissue Types	$R_L(\frac{d{\rho }_{s,x}^{\prime }/{\rho }_{s,x}^{\prime }}{d{\mu }_{x,L}^{\prime }/{\mu }_{x,L}^{\prime }})$	$R_H(\frac{d{\rho }_{s,x}^{\prime }/{\rho }_{s,x}^{\prime }}{d{\mu }_{x,H}^{\prime }/{\mu }_{x,H}^{\prime }})$
kV-kV	Soft Tissues	3.82	4.82
	Bone Tissues	4.85	5.84
	All Tissues	4.19	5.18
kV-MV	Soft Tissues	0.34	1.34
	Bone Tissues	0.21	1.21
	All Tissues	0.30	1.30
MV-MV	Soft Tissues	6.36	7.35
	Bone Tissues	2.63	3.63
	All Tissues	5.38	6.34