Table 1.
Linear attenuation coefficients.
| Image region | 511 keV μ (1∕cm) | CTACμ(1∕cm) |
|---|---|---|
| Cylinder phantom and head coil | ||
| Air | −0.0009 | 0.0003 |
| Water (uniform) | 0.0933 | 0.0932a |
| Water (artifact) | N∕A | 0.0924 |
| Coil-1 | 0.1038 | 0.1534 |
| Coil-2 | 0.1116 | 0.1543 |
| Coil-3 | 0.1034 | 0.1536 |
| Torso phantom and torso coil | ||
| Water | 0.0911 | 0.0933 |
| Spine insert | 0.1630 | 0.1437 |
| Coil-1 (anterior) | 0.1066 | 0.1604 |
| Coil-2 (anterior) | 0.0890 | 0.1595 |
| Coil-3 (posterior) | 0.1001 | 0.1552 |
| Coil-4 (posterior) | 0.1012 | 0.1569 |
a
The linear attenuation coefficient of water measured using CT without the MR coil present was 0.0931∕cm.NOTE: Coil ROIs shown on Fig. 4 are only for display; actual ROIs used for analyses were smaller than coil structure.