TABLE VI.
Optimal cutoffs (percent of pixels passing gamma for planar/array dosimeters or percent difference for the cc04 single ion chamber) given for all dosimetric systems, both with and without weighting by the prevalence of a failing plan and the cost of falsely labeling a failing plan as passing. This table is ordered by the Youden index (no weighting) optimal thresholds for percent of pixels passing. The calculation of confidence intervals was based on a normal approximation, so there is an opportunity to exceed 100% of pixels passing.
| Youden index (no weighting) | Weighted optimal cutoff | |
|---|---|---|
| Device | Threshold (dose difference for ion chamber; % of pixels passing for all else) with 95% confidence intervals | Threshold (dose difference for ion chamber; % of pixels passing for all else) with 95% confidence intervals |
| cc04 ion chamber | 1.6 ± 1.1 | 3.0 ± 0.7 |
| EDR2 film at 2%/2 mm | 68 ± 15 | 60 ± 6.4 |
| Planned angle MapCheck at 2%/2 mm (snc) | 69 ± 19 | 54 ± 13 |
| ArcCheck at 2%/2 mm (snc) | 74 ± 14 | 49 ± 11 |
| Planned angle MapCheck at 2%/2 mm (DL) | 80 ± 20 | 48 ± 23 |
| AP composite MapCheck at 2%/2 mm (snc) | 82 ± 9 | 66 ± 10 |
| AP field-by-field MapCheck at 2%/2 mm (snc) | 85 ± 8 | 72 ± 17 |
| Planned angle MapCheck at 3%/3 mm (DL) | 85 ± 14 | 69 ± 16 |
| AP composite MapCheck at 2%/2 mm (DL) | 89 ± 7 | 62 ± 19 |
| AP field-by-field MapCheck at 2%/2 mm (DL) | 90 ± 4 | 78 ± 6 |
| ArcCheck at 3%/3 mm (snc) | 92 ± 7 | 69 ± 14 |
| Planned angle MapCheck at 3%/3 mm (snc) | 94.9 ± 9.5 | 70 ± 13 |
| ArcCheck at 5%/3 mm (snc) | 96 ± 2 | 92 ± 6 |
| AP field-by-field MapCheck at 3%/3 mm (snc) | 96 ± 4.6 | 90 ± 7.2 |
| EDR2 film at 3%/3 mm | 97 ± 9.7 | 76 ± 8 |
| AP composite MapCheck at 3%/3 mm (DL) | 98 ± 2 | 82 ± 13 |
| AP composite MapCheck at 3%/3 mm (snc) | 98 ± 2 | 83 ± 13 |
| AP field-by-field MapCheck at 3%/3 mm (DL) | 98 ± 2.6 | 92 ± 4.4 |
| Planned angle MapCheck at 5%/3 mm (DL) | 98 ± 5 | 85 ± 9.3 |
| Planned angle MapCheck at 5%/3 mm (snc) | 98.5 ± 7.2 | 83 ± 12 |
| AP field-by-field MapCheck at 5%/3 mm (snc) | 98.7 ± 1.9 | 96 ± 2.4 |
| AP field-by-field MapCheck at 5%/3 mm (DL) | 99.4 ± 1.1 | 98 ± 1.6 |
| AP composite MapCheck at 5%/3 mm (snc) | 99.6 ± 0.4 | 98.5 ± 0.7 |
| AP composite MapCheck at 5%/3 mm (DL) | 99.7 ± 0.4 | 96 ± 3 |
| EDR2 film at 5%/3 mm | 99.8 ± 1.5 | 91 ± 6 |