Table 3:
The NIST uncertainty budgets for the IC activity measurement of the 18F and 64Cu ampoules (May 2016)
| Uncertainty contributions due to | Evaluation method | 18F | 64Cu | ||
|---|---|---|---|---|---|
| Relative std uncert. × 104 | Comments | Relative std uncert. × 104 | Comments | ||
| Ampoule to RRS2 ratio | A | 2 | Average std deviation, 90 meas. of 18F, 108 meas. of RRS 50 | 2 | Average std deviation, 82 or 90 meas. of 64Cu on each of the two ampoules, 108 meas. of RRS 50 |
| Activity estimation | A | 0.5 | Std deviation of the estimation in each of two ampoules | 0.5 | Std deviation of the estimation in each of two ampoules |
| RRS ratio, 1000 to 50 | B | 7 | Uncertainty attending the ratio between RRS 1000, used in the calib. of the IC, and RRS 50, used in this meas. | - | Not required; both the calibration and this meas. used RRS 50. |
| Weighing | B | 7 | Mass of solution in the ampoules | 7 | Mass of solution in the ampoules |
| Dilution factor | B | 5 | 6 | ||
| Background | A | 0.09* | 228 measurements | 0.09* | 142 measurements |
| Decay correction | B | 0.4 | From uncert. for 18F half-life | 0.l | From uncert. for 64Cu half-life |
| Calibration factor of IC (see appendix 2) | B | 38 | Calibration by LTAC in August 2015 | 58 | Calibration by LTAC in March 2016 |
| Impurities | B | - | 0.0l | ||
| Relative combined std uncertainty | 40 | 59 | |||
*
Included in the first uncertainty component (ampoule to RRS ratio)