Table 1.

The CT number range, relative electron densities of the center HU bin, and mean excitation energies for tissues. Group 27 represents high Z materials such as titanium implants.

Group	Tissue	HU range	Relative electron density	I-value (eV) [Nominal]	I-value (eV) [−10% ; +10%]
1		[;−951]	0.024	85.68	[77.11; 94.25]
2	Lung	[−950; −121]	0.476	69.44	[62.50; 76.38]
3	Adipose tissue	[−120; −83]	0.929	60.59	[54.53; 66.65]
4		[−82; −53]	0.958	62.23	[56.01; 68.45]
5	Yellow marrow	[−52; −23]	0.982	63.97	[57.57; 70.37]
6	Red marrow	[−22; 7]	1.007	65.39	[58.85; 71.93]
7		[8; 18]	1.024	66.58	[59.92; 73.24]
8	Soft tissues	[19; 79]	1.052	69.02	[62.12; 75.92]
9		[80; 119]	1.102	69.58	[62.62; 76.54]
10		[120; 199]	1.094	69.03	[62.13; 75.93]
11		[200; 299]	1.14	71.72	[64.55; 78.89]
12	Sternum	[300; 399]	1.19	74.75	[67.28; 82.23]
13		[400; 499]	1.24	77.66	[69.89; 85.43]
14	Femur, head	[500; 599]	1.291	80.2	[72.18; 88.22]
15		[600; 699]	1.342	82.83	[74.01; 90.45]
16	Ribs	[700; 799]	1.391	85.42	[76.88; 93.96]
17		[800; 899]	1.441	88.16	[79.34; 96.98]
18	Cranium	[900; 999]	1.491	90.42	[81.38; 99.46]
19		[1000; 1099]	1.542	92.48	[83.23; 101.73]
20		[1100; 1199]	1.592	94.85	[85.37; 104.34]
21		[1200; 1299]	1.642	96.8	[87.12; 106.48]
22		[1300; 1399]	1.693	98.78	[88.90; 108.66]
23	Bone	[1400; 1499]	1.743	100.8	[90.72; 110.88]
24		[1500; 1599]	1.794	102.22	[92.00; 112.44]
25		[1600; 1999]	1.931	102.22	[92.00; 112.44]
26		[2000; 3060]	2.287	102.22	[92.00; 112.44]
27	High Z Material	[3061;]	3.757	233	[209.7; 256.3]