Table 1.

Summary of Calibration Phantom, Densitometric and Modulus Relationships, Scanner and Scanner Settings

Author, Year	Anatomical Location	Phantom Type	Phantom Manufacturer	Densitometric Relationship (g/cm3)	Density-Modulus Relationship (MPa)	Validation Measure Experimental vs. FEM (Metric Value(s))	Scanner	Peak Voltage (kVp)	Tube Current (mA)/Time Product (mAs)	Voxel Dimensions (mm)
(Tarala et al. 2011)	Femur	HA	Image Analysis	ρHA = ρash	NR	Displacement	NR	NR	NR	NR
						CLS Stem R2 = 0.95 EPOCH Stem R2 = 0.88
(Cong et al. 2011)	Femur	K2HPO4	Mindways	ρash = ${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ = −0.009 + 0.0007 HU ρash/ρapp = 0.6a		Axial Stiffness	Somatom Definition, Siemens	120	216 mAs	0.40 × 0.45 × 0.45
					E = 14664ρash 1.49	R2(y = x) = −1.40
					E = 10500ρash 2.29	R2(y = x) = −4.97
					E = 17546ρash 3	R2(y = x) = −6.93
					E = 8050ρash 1.16	R2(y = x) = 0.50
					E = 15000e -4.91e-2.63ρash	R2(y = x) =0.71
					E = 20000e ^ -5.19e-2.10ρash	R2(y = x) = 0.69
					E = 55000e ^ -5.40e-2.63ρash	R2(y = x) = 0.69
(Dragomir-Daescu et al. 2011)	Femur	K2HPO4	Mindways	ρash = ${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ = −9*10−3 + 7* 10−4*HU ρash/ρapp = 0.6a	E = 14664ρash 1.49	Axial Stiffness	Somatom Definition, Siemens	120	216 mAs	0.40 × 0.30 to 0.45
						R2 = 0.87
						Ultimate Load
						R2 = 0.93
(Keyak et al. 2011)	Femur	HA	Image Analysis	NR	NR	NR	NR	120	140 mAs	NR
(Trabelsi and Yosibash 2011)	Femur	K2HPO4	NR	ρash = 1.22${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0523b	Ecort = 10200ρash 2.01 Etrab = 5307ρash + 469	Strain	NR	NR	NR	NR
						R2 = 0.982 empirical R2 = 0.939 MM-based
(Trabelsi et al. 2011)	Femur	K2HPO4	Mindways	ρash = 1.22${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0523b	Ecort = 10200ρash 2.01 Etrab = 5307ρash + 469	Displacement	Lightspeed VCT, GE Healthcare	120	90 mAs	1.0 × 0.488 to 0.547
						R2 = 0.871
						Strain
						R2 = 0.951
						Axial Stiffness
						R2 = 0.619
(Amin et al. 2011)	Femur	European Spine Phantom	NA	NR	NR	NE	Lightspeed QX/i, GE Healthcare	NR	NR	2.5 × 0.74 × 0.74
(Op Den Buijs and Dragomir-Daescu 2011)	Femur	K2HPO4	Mindways	ρash = ${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ = 7.0*10−4HUc	E = 29800ρash 1.56	Axial Stiffness	Somatom Definition, Siemens	120	216 mA	0.40 × 0.29 to 0.41
						R2 = 0.76
						Strength
						R2 = 0.71
(Koivumäki et al. 2012a)	Femur	HA	Osteo	ρash = ρHA	E = 10095ρash	Fracture Load	Sensation 16, Siemens	120	100 mAs	0.75 × 0.25 × 0.25
						R2 = 0.87
(Shim et al. 2012)	Femur	NR	NR	NR	E = 6750.3ρash 2.01	NE	NR	NR	NR	NR
(Gong et al. 2012)	Femur	HA	Image Analysis	ρHA to ρapp and converted to ρash d – Equation NR	E = 0.001 for ρash = 0 E = 33900ρash 2.20 for 0 < ρash < 0.27 E = 5307ρash + 469 for 0.27 < ρash < 0.60 E = 10200ρash 2.01 for ρash > 0.60	NE	Lightspeed 16, GE Healthcare	80	280 mA	2.5 × 0.9375 × 0.9375
(Tomaszewski et al. 2012)	Femur	HA	NR	ρash = 0.0633 + 0.887ρHA e	NR but referenced	NE	NR	NR	NR	NR
(Keaveny et al. 2012)	Femur	K2HPO4	Mindways	NR	NR but referenced	NE	NR	80	280 mAs	3.0 × 0.78 to 0.94 × 0.78 to 0.94
(Koivumäki et al. 2012b)	Femur	HA	Osteo	NR	NR	Cortical Fracture Load	Sensation 16, Siemens	120	100 mAs	0.75 × 0.25 × 0.25
						R2 = 0.73
(Ruess et al. 2012)	Femur	NR	NR	${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ = 10−3(0.793)HU ρash = 1.22${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0523b	Ecort = 10200ρash 2.01 Etrab = 5307ρash + 469	Strain	Brilliance 64, Phillips	120	250 mAs	1.25 × 0.195 × 0.195
						R2 = 0.918–0.981 See paper for specifics by method
(Eberle et al. 2013a)	Femur	K2HPO4	Mindways	ρash = 1.22${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0523b ρHA = 1.15${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ - 0.0073f ρash = 0.8772ρHA + 0.0789 ρapp = 1.58 ρash + 0.00011		Strain	Lightspeed VCT, GE Healthcare	120	90 mAs	1.0 × 0.547 × 0.547 OR 1.0 × 0.488 × 0.488
					E = 10200ρash 2.01	Bland-Altman (mean) −9%
					E = 6850ρapp 1.49	Bland-Altman (mean) −10.6%
					E = 15100${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}^{2.225}$	Bland-Altman (mean) −7.9%
						Displacement
					E = 10200ρash 2.01	Bland-Altman (mean) −20.9%
					E = 6850ρapp 1.49	Bland-Altman (mean) −22.9%
					E = 15100${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}^{2.225}$	Bland-Altman (mean) 1.6%
						Axial Stiffness
					E = 10200ρash 2.01	Bland-Altman (mean) 15.8%
					E = 6850ρapp 1.49	Bland-Altman (mean) 22.6%
					E = 15100${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}^{2.225}$	Bland-Altman (mean) −9.6%
(Eberle et al. 2013b)	Femur	K2HPO4	Mindways	ρash = 1.22${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0523b ρHA = 1.15${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ - 0.0073f ρash = 0.8772ρHA +0.0789 ρapp = 1.58 ρash + 0.00011		Strain	Lightspeed VCT, GE Healthcare	120	90 mAs	1.0 × 0.547 × 0.547 OR 1.0 × 0.488 × 0.488
					E = 12486${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}^{1.16}$	Relative Error (mean) 5%
					E = 8346ρapp 1.50	Relative Error (mean) −28%
					E = 8050ρash 1.16	Relative Error (mean) 18%
					E = 25000e^ -5.40e-2.10ρash	Relative Error (mean) −16%
					E = 6850ρapp 1.49	Relative Error (mean) −12%
						Displacement
					E = 12486 ${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}^{1.16}$	Relative Error (mean) −10%
					E = 8346ρapp 1.50	Relative Error (mean) −40%
					E = 8050ρash 1.16	Relative Error (mean) 3%
					E = 25000e-5.40e-2.10ρash	Relative Error (mean) −29%
					E = 6850ρapp 1.49	Relative Error (mean) −26%
						Stiffness (N/mm)
					E = 12486 ${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}^{1.16}$	Relative Error (mean) 6%
					E = 8346ρapp 1.50	Relative Error (mean) 56%
					E = 8050ρash 1.16	Relative Error (mean) −6%
					E = 25000e-5.40e-2.10ρash	Relative Error (mean) 31%
					E = 6850ρapp 1.49	Relative Error (mean) 28%
(Haider et al. 2013)	Femur	K2HPO4	Mindways	ρash = 0.00106${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0389g ρash/ρapp = 0.6b	E = 6850ρapp 1.49	NE	NR	NR	NR	0.5 × 0.49 × 0.49
(Dall’Ara et al. 2012)	Femur	HA	QMR	BMD to BV/TV from μCT	Relation to BV/TV – Equation NR	Axial Stiffness	Brilliance 64, Phillips	120	100 mAs	1.0 × 0.33 × 0.33
						Stance: R2 = 0.449 Side: R2 = 0.869
(Nishiyama et al. 2013)	Femur	HA	B-MAS200	ρash = ρHA	E = 10500ρash 2.29	Axial Stiffness	Discovery CT750HD, GE Healthcare	120	60 mAs	0.625 × 0.439 × 0.439
						R2 = 0.89
						Failure Load
						R2 = 0.81
(Kersh et al. 2013)	Femur	HA	NR	BV/TV = 9.3BMD + 3 from μCTh	NR	NE	Brilliance 64, Phillips	120	100 mA	0.60 × 0.36 × 0.36
(Keyak et al. 2013)	Femur	HA	Image Analysis	ρash = 0.0633 + 0.887ρHA i	Etrab = 14900ρash 1.86	NE	Sensation 4, Siemens	120	140 mAs	NR
(Hambli and Allaoui 2013)	Femur	HA	Osteo	ρHA = 6.932*10−4HU - 5.68*10−4 ρash = 1.22${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0523b	E = 33900ρash 2.20 for 0 < ρash < 0.27 E = 5307ρash + 469 for 0.27 < ρash < 0.60 E = 10200ρash 2.01 for ρash > 0.60	Fracture Load	Somatom Plus 4, Siemens	120	160 mAs	0.70 × 0.25 × 0.25
						R2 = 0.943
(Carballido-Gamio et al. 2013)	Femur	Both	Mindways & Image Analysis	NR	NR	NE	Sensation, Siemens	NR	NR	2.5 × 0.74 × 0.74 & 1.0 × 0.98 × 0.98
(Nishiyama et al. 2014)	Femur	Both	Mindways & B-MAS200	ρash = ρHA	E = 10500ρash 2.29	NE	Somatom Cardiac 64, Siemens	120	250 mAs	0.50 × 0.625 × 0.625
(Luisier et al. 2014)	Femur	HA	QMR	BMD to BV/TV from μCTj	Eo = 6614	Ultimate Force	Brilliance 64, Phillips	120	100 mA	1.0 × 0.33 × 0.33
						Stance: R2 = 0.797 Side: R2 = 0.842
(Enns-Bray et al. 2014)	Femur	NR	NR	ρash = ρQCT	E3 = 10500ρash 2.29 See paper for anisotropic modulus	Axial Stiffness	Discovery CT750HD, GE Healthcare	120	60 mAs	0.625 × 0.625 × 0.625
						Anisotropic: R2 = 0.783 Isotropic: R2 = 0.792
						Ultimate Strength
						Anisotropic: R2 = 0.355 Isotropic: R2 = 0.350
(Anez-Bustillos et al. 2013)	Femur	HA	Image Analysis	NR	Experimentally derived	Axial Rigidity	ACQSim, Phillips	120	220 mA	3.0 × 0.9375 × 0.9375
						R2 = 0.82
						Bending Rigidity
						R2 = 0.86
						Failure Load
						R2 = 0.89
(Mirzaei et al. 2014)	Femur	K2HPO4	Mindways	ρash = 1.22${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ + 0.0526b	E = 33900ρash 2.20 for 0 < ρash < 0.27 E = 5307ρash + 469 for 0.27 < ρash < 0.60 E = 10200ρash 2.01 for ρash > 0.60	Load	Somatom 64, Siemens	140	80 mAs	1.0 × 0.50 × 0.50
						R2 = 0.809–0.886 See paper for specifics by method
(Arachchi et al. 2015)	Femur	HA	NR	NR	NR	NE	Brilliance 64, Phillips & Somatom Plus 4, Siemens	140	206 mAs	2.0 × 0.29 × 0.29
(Kheirollahi and Luo 2015)	Femur	NR	NR	ρash = 0.04162 + 0.000854HU	E = 10500ρash 2.29	NE	NR	NR	NR	NR
(Carballido-gamio et al. 2015)	Femur	Both	Mindways & Image Analysis	vBMD reported	NR	NE	Lightspeed QX-I, Lightspeed VCT, Lightspeed 16, GE Healthcare & Biograph 16, Siemens	NR	NR	2.0 × 0.742 × 0.742 OR 2.5 × 0.938 × 0.938 OR 1.0 × 0.977 × 0.977
(Kaneko et al. 2015)	Femur	HA	B-MAS200	ρash = ρHA	NR	NE	Light Speed Ultra16, GE Healthcare	120	80 mA	NR
(Varghese et al. 2011)	Femur, Tibia, Humerus, Radius	K2HPO4	Mindways	NR	NR	Strain	Lightspeed 16, GE Healthcare	80	200 mAs	0.625 × 0.625 × 0.625
						R2 = 0.61–0.99 See paper for specifics by method
(Kopperdhal et al. 2014)	Spine & Femur	HA	Image Analysis	BMD related to HU	NR	NE	Somatom Plus 4, Siemens	120	150 mAs	Spine: 1.0 × 1.0 × 1.0 Femur: 1.5 × 1.5 × 1.5
(Kleerekoper et al. 2014)	Spine & Femur	NR	NR	NR	NR	NE	NR	NR	NR	NR
(Keaveny et al. 2014)	Spine & Femur	HA	European Spine Phantom	NR	NR	NE	NR	120	Femur: 170 mAs Spine: 100 mAs	NR
(Zeinali et al. 2010)	Spine	K2HPO4	Mindways	BMD related to HU	Ez = −34.7 + 3230${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ Ez = −2980${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ 1.05 ${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$ = 0.0527 g/cc Ex = Ey = 0.333Ez	Strength	Somatom Plus 64, Siemens	140	400 mA	1.0 × 0.25 × 0.25
						Linear elastic–plastic: R2 = 0.937 Linear elastic-perfectly plastic: R2 = 0.855 Linear elastic: R2 = 0.831 Min. sectional: R2 = 0.863
(Tawara et al. 2010)	Spine	HA	B-MAS200	ρapp = 0.0 (HU < −1) ρapp = (0.733HU + 4.51)*10−3 (−1 ≤ HU)	E = 0.001 for ρash = 0 E = 33900ρash 2.20 for 0 < ρash < 0.27 E = 5307ρash + 469 for 0.27 < ρash < 0.60 E = 10200ρash 2.01 for ρash > 0.60	NE	Hitachi	120	NR	1.0 × 0.39 × 0.39
(Unnikrishnan and Morgan 2011)	Spine	HA	Image Analysis	ρHA based	Ezz = −34.7 + 3.230ρHA Exx = Eyy = 0.333	NE	Light Speed VCT, GE Healthcare	120	240 mA	0.625 × 0.31 × 0.31
(Christiansen et al. 2011)	Spine	HA	Image Analysis	ρHA based	NR	NE	Light Speed Plus, GE Healthcare	120	100 to 360 mAs	2.5 × 0.68 × 0.68
(Imai 2011)	Spine	HA	NR	ρash = ρHA	Ecort = 10000	NE	Light Speed QX/i, GE Healthcare	120	360 mA	2.0 × 0.35 × 0.35
(Dall’Ara et al. 2012)	Spine	K2HPO4	Mindways	BV/TV using the relationships BV/TV = 0 for BMD < −100 BV/TV = 0.0942*BMD-0.0297 for −100 < BMD < 1061 BV/TV = 1061 for BMD >1061	E = 8780	Strength	Brilliance 64, Pillips	120	100 mA	0.45 × 0.39 × 0.39
						hFE: R2 = 0.79
						Failure Load
						hFE: R2 = 0.78
(Wang et al. 2012)	Spine	HA	Image Analysis	vBMD based	NR	Strength	NR	120	150 mAs	NR
						R2 = 0.85
(Unnikrishnan et al. 2013)	Spine	HA	Image Analysis	BMD related to HU	Ez = −34.7 + 3230ρHA Ez = −2980ρHA 1.05 ρHA = 0.0527 g/cc Ex = Ey = 0.333Ez	NE	Light Speed VCT, GE Healthcare	120	240 mA	0.625 × 0.3125 × 0.3125
(Lu et al. 2014a)	Spine	Both	Mindways & QRM	NR	NR	NE	Sensation 64, Siemens	120	360 mAs	0.60 × 0.32 × 0.32 OR 0.30 × 0.18 × 0.18
(Matsuura et al. 2014)	Spine	K2HPO4	Mindways	ρash = ${\mathrm{\rho }}_{{\mathrm{K}}_2\mathrm{H}\mathrm{P}{\mathrm{O}}_4}$	ρash = 0: E = 0.001 ρash > 0: E = 1890 ρash 1.92	Fracture Load	Somatom Definition, Siemens	120	210 mA	0.40 × 0.30 × 0.30
						R2 = 0.78
						Axial Stiffness
						R2 = 0.39
(Lu et al. 2014b)	Spine	HA	QMR	BMD related to HU	Ez = 2980(ρHA/1000)1.05 for ρHA < 52.7 [mgHA/cc] Ez = = −34.7 + 3230ρHA for ρHA > 52.7 [mgHA/cc]	NE	Mx8000, Phillips	90 & 120	100 & 150 mAs	1.3 × 0.30 × 0.30
(Campoli et al. 2014)	Scapula	NR	NR	ρapp = HU + 0.00039	E = 6850ρapp 1.49	NE	Somatom Definition, Siemens	NR	NR	0.6 × 0.6 × 0.6
(Pomwenger et al. 2014)	Scapula	NR	NR	ρapp = 1.1187*10−3*HUk assumed ρapp = 0 no bone & ρapp = 1.8 for bone	E = 1049.45ρapp 2 ρapp < 0.35 E = 3000ρapp 3 ρapp > 0.35	NE	NR	NR	NR	NR
(Hermida et al. 2014)	Scapula	K2HPO4	Mindways	NR	Ecort = 20000	NE	NR	NR	NR	NR
(Edwards et al. 2013)	Tibia	HA	QRM	ρHA = BMD ρapp/ρHA = 0.626	E3 = 6570ρapp 1.37 Emin = 0.01 E1 = 0.574E3 E2 = 0.577E3	Rotation Stiffness	Brightspeed, GE Healthcare	120	200 mA	0.625 × 0.352 × 0.352
						R2 = 0.920
						Ultimate Strength
						R2 = 0.753
(Nazemi et al. 2015)	Tibia	K2HPO4	Mindways	ρash = 0.55 ρapp g ρash = 0.597ρdry g ρreal = 1.8 g/ccl ρapp = ρreal*BV/TV BMD = 0.904ρash - 0.0321g ρash = 1.06*BMD + 0.0389g		Axial Stiffness	Aquilion 64, Tobisha	120	150 mAs	0.5 × 0.5 × 0.5
					E = 15520ρapp 1.93	R2 = 0.75
					E = 6570ρapp 1.37	R2 = 0.65
					E = 33200ρash 2.2	R2 = 0.70
					E = 4778ρapp 1.99	R2 = 0.69
					E = 3311ρdry 1.66	R2 = 0.67
					E = 3890ρdry 2	R2 = 0.69
					E = 6310(BV/TV)2.1	R2 = 0.70
(McErlain et al. 2011)	Knee	SB3	Gamex	NR	NR	NE	Multistar, Siemens	90	40 mAs	NR
(Synek et al. 2015)	Radius	NR	NR	BMD to BV/TV from μCT	Multiple – Refer to paper	Axial Stiffness	Discovery CT750HD. GE Healthcare	140	260 mA	0.63 × 0.20 × 0.20
						Isotropic-Homogeneous R2 = 0.500 Isotropic-Heterogeneous R2 = 0.816 Orthotropic-Heterogeneous R2 = 0.807

HA Hydroxyapatite, K ₂ HPO ₄ Dipotassium Phosphate, NR Not Reported, BMD Bone Mineral Density, BV/TV Bone Volume/Total Volume, NE No Experimental; ^a (Schileo et al. 2008); ^b (Les et al. 1994); ^c (Suzuki et al. 1991); ^d (Keyak et al. 1997); ^e (Keyak et al. 2005); (Faulkner et al. 1993); ^g (Keyak et al. 1994); ^h (Dall’Ara et al. 2011); ^I (Keyak et al. 2005); ^j (Pahr and Zysset 2009); ^k (Gupta and Dan 2004); ^l (Carter and Hayes 1977)