Table 3.
Parameters to model the absorbed dose from primary photon fluence in water.
| Symbol | Description | In-Plane | Cross-Plane | Source |
|---|---|---|---|---|
| αQ1 | Incident electron charge empirical adjustment parameter for Gaussian 1 | 1.24 | 1.20 | This Worka |
| αQ2 | Incident electron charge empirical adjustment parameter for Gaussian 2 | 0.62 | 1.00 | “ |
| ασ1 | Width parameter adjustment factor for Gaussian 1 | 0.79 | 0.52 | “ |
| ασ2 | Width parameter adjustment factor for Gaussian 2 | 0.51 | 0.74 | “ |
| αx̄2 | Adjustment parameter for the mean of Gaussian 2 | 0.82 | 1.51 | “ |
| αw | Adjustment parameter to the μt of water | 0.77 | “ | |
| d0 | Upstream distance from the effective photon source to the virtual photon source (mm) | 6.03 | “ | |
| μw | Linear attenuation coefficient of water for 2 MeV photons (1/cm) | 4.942 × 10−2 | (Hubbell and Seltzer, 2011) | |
| SSD | Source-to-surface-distance (cm) | 100 | 100 | (Kaderka, 2012) |
| SDD | Source-to-diaphragm-distance (cm) | 47 | 37.7 | (Elekta, 2007) |
a
From iterative fitting procedure