TABLE 2
Calculated Linear Attenuation Coefficients (Total Minus Rayleigh Scattering) of Water, Bone, and Selected Metals
| Material | Atomic number (Z) | Mass density (ρ) | Linear attenuation coefficient (μ) [cm−1] | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 50 keV | 80 keV | 140 keV | 511 keV | Ratio
 | |||||||
| Water (H2O) | 8, 1 | 1.0 | 0.21 | 0.18 | 0.15 | 0.096 | 1.8 | ||||
| Bone* | 20, 15, 8, 1* | 1.8* | 0.96 | 0.42 | 0.27 | 0.155 | 2.7 | ||||
| Titanium (Ti) | 22 | 4.5 | 5.1 | 1.65 | 0.73 | 0.36 | 4.5 | ||||
| Nickel (Ni) | 28 | 8.9 | 20.7 | 5.9 | 1.96 | 0.75 | 8 | ||||
| Tantalum (Ta) | 73 | 16.7 | 86.3 | 122.4 | 27.8 | 2.04 | 60 | ||||
| Iridium (Ir) | 77 | 22.4 | 136.6 | 186.0 | 43.9 | 2.96 | 63 | ||||
| Platinum (Pt) | 78 | 21.4 | 135.8 | 181.1 | 43.7 | 2.88 | 63 | ||||
| Lead (Pb) | 82 | 11.3 | 83.5 | 23.9 | 25.7 | 1.64 | 15 | ||||
↵* For purpose of calculation, attenuation properties of bone were assumed to be equivalent to hydroxyapatite (Ca10(PO4)6(OH)2) with mass density of 1.8 (equal to cortical bone).