Table 2.
The optimization parameters and relative penalties for implementing the AFI strategy for SRS/SRT multiple target plans.
| Structure | Volume (%) | Min Dose (% of Rx) | Max Dose (% of Rx) | Penalty (relative number) |
|---|---|---|---|---|
| PTV | 0 | ‐ | 140 | 200 |
| 100 | 100 | ‐ | 200 | |
| OptiForR50shell | 0 | ‐ | 100 | 200 |
| %VOpti | ‐ | 45 | 200 | |
| iShell | 0 | ‐ | 45 | 200 |
There will be a unique set of such shells and optimization parameters for each PTV in a multiple target case. OptiForR50shell is a shell expansion of the PTV with the expansion margin given by M in Eq. (2), and %VOpti is given by Eq. (3), and both parameters are dependent on the R50%Goal specific to that PTV. The iShell is a single global structure defined by Eq. (4), which is the brain minus all the PTVs and OptiForR50shell. The penalties listed are a defined part of the AFI approach but may need minor modifications for planning systems other than Eclipse.