Table 2.
The plan conformity indexes, all fitting parameters from Equation (1), and the total number of monitor units (MUs) for the stereotactic radiosurgery plans with 90–50% prescription isodose levels (IDLs) for an example patient (Patient 2)
| IDL | 90% | 80% | 70% | 60% | 50% |
|---|---|---|---|---|---|
| CI | 1.230 | 1.230 | 1.230 | 1.221 | 1.230 |
| a1 | 15.720 | 11.000 | 10.181 | 9.940 | 9.760 |
| b1 | 0.136 | 0.239 | 0.280 | 0.276 | 0.260 |
| a2 | 3.506 | 8.248 | 9.032 | 9.437 | 9.315 |
| b2 | 0.0371 | 0.0620 | 0.0651 | 0.0648 | 0.0634 |
| Total MU | 2465 | 2792 | 3200 | 3755 | 4531 |
CI, conformity index.
For this patient, the plan with 70% IDL achieved both the greatest dose-dropping speed (b1), and the greatest b2, the smaller exponential decay coefficient in equation (1) characterizing the dose drop-off in the low dose region.