Table 2.
Mean measurement errors. Subdivided by nominal design concentrations, mAs and kVp
| True BMD concentration (mg/cm3) | mAs | 120 kVp | 140 kVp | ||
|---|---|---|---|---|---|
| Measurement error | Measurement error | ||||
| mg/cm3 | % | mg/cm3 | % | ||
| 50* | All | -0.9 ± 2.1 | -1.8 ± 4.0 | 1.6 ± 1.1 | 3.1 ± 2.1 |
| 200 | 0.3 ± 1.5 | 0.5 ± 2.9 | 0.9 ± 1.0 | 1.8 ± 1.9 | |
| 100 | -0.2 ± 0.6 | -0.5 ± 1.1 | 1.5 ± 0.6 | 2.9 ± 1.1 | |
| 50 | -2.8 ± 2.6 | -5.5 ± 5.1 | 2.3 ± 1.5 | 4.5 ± 2.9 | |
| 100* | All | -3.0 ± 2.7 | -2.9 ± 2.6 | -0.7 ± 1.8 | -0.7 ± 1.7 |
| 200 | -2.7 ± 1.8 | -2.6 ± 1.8 | -0.5 ± 2.0 | -0.5 ± 1.9 | |
| 100 | -2.1 ± 3.8 | -2.0 ± 3.7 | -0.5 ± 2.0 | -0.5 ± 1.9 | |
| 50 | -4.1 ± 2.2 | -4.0 ± 2.1 | -1.1 ± 1.6 | -1.1 ± 1.5 | |
| 200* | All | -10.6 ± 5.3 | -5.3 ± 2.7 | -6.0 ± 2.7 | -2.9 ± 1.3 |
| 200 | -9.6 ± 4.6 | -4.7 ± 2.3 | -6.4 ± 1.6 | -3.2 ± 0.8 | |
| 100 | -10.5 ± 5.2 | -5.2 ± 2.6 | -6.7 ± 3.1 | -3.3 ± 1.5 | |
| 50 | -11.8 ± 6.7 | -5.8 ± 3.4 | -4.8 ± 3.1 | -2.4 ± 1.6 | |
Data are given as mean ± standard deviation. For 50 mg/cm3 nine measurements and for 100 and 200 mg/cm3 18 measurement were performed at both 120 and 140 kVp (three and six,respectively, per mAs value)
BMD bone mineral density, kVp kilovoltage peak, mAs milliampere second
* Phantom specific concentrations (ESP-143; 51.2, 102.3 and 201.2 mg/cm3 HA and BDC-03-29; 104.4 and 206.2 mg/cm3 HA) were used to determine measurement error