Table 1.
Summary of treatment planning properties obtained from the IROC SRS head phantom study to determine the value of Δr.
| VPTV (cm3) | rPTV (cm) | CIRTOG | HIRTOG | GM (cm) | rIDC50% (cm) | Δr (cm) | PIDL |
|---|---|---|---|---|---|---|---|
| 0.19 | 0.36 | 1.18 | 1.80 | 0.20 | 0.57 | 0.22 | 57.3 |
| 0.55 | 0.51 | 0.99 | 1.26 | 0.25 | 0.76 | 0.25 | 80.8 |
| 0.99 | 0.62 | 1.04 | 1.38 | 0.27 | 0.90 | 0.28 | 72.8 |
| 1.96 | 0.78 | 1.04 | 1.36 | 0.30 | 1.09 | 0.31 | 83.2 |
| 2.96 | 0.89 | 1.03 | 1.31 | 0.34 | 1.23 | 0.34 | 78.5 |
| 3.97 | 0.98 | 1.04 | 1.27 | 0.35 | 1.34 | 0.36 | 79.6 |
| 6.93 | 1.18 | 0.99 | 1.22 | 0.40 | 1.58 | 0.40 | 85.4 |
| 20.45 | 1.70 | 0.99 | 1.21 | 0.52 | 2.22 | 0.52 | 88.7 |
| 43.99 | 2.19 | 0.99 | 1.21 | 0.65 | 2.83 | 0.64 | 91.7 |
| Ave CIRTOG | 1.03 | ||||||
| Std Dev | 0.06 |
CIRTOG is the conformity index, and HIRTOG is the homogeneity index. All plans are normalized volumetrically to D99% (99% of the PTV volume receives 100% of the prescription dose). The equivalent PIDL is determined by matching the coverage of the D99% prescription. Δr values are calculated from the difference of rIDC50% and rPTV, assuming both volumes are spherical. Note the Eclipse GM values are nearly identical to Δr.