Table 4.

The uncertainty propagation ratio (UPR) of SPR variation over HU variation $(\frac{{\sigma }_{\mathit{\text{SPR}}}/\mathit{\text{SPR}}}{{\sigma }_{\mathit{\text{HU}}}/\mathit{\text{HU}}})$ for different tissue groups and DECT-based methods.

Method	UPR	Lung	Soft	Bone
HS	R80	0.63	0.72	0.56
	R150	1.71	1.87	1.57
Bourque	R80	0.69	0.68	0.66
	R150	1.74	1.76	1.59