Table 1. Summary of nine SFRT dosimetric parameter specifications in the six-arm study.
| Treatment Arm | # of Animals | Vol-Avg Dosea (Gy) | Peak Surface Dose (Gy) | Valley Surface Dose (Gy) | EUD (Ta/Ne) | PVDRf | Valley Width (mm) | Peak Width (mm) | % Volume Irradiated |
|---|---|---|---|---|---|---|---|---|---|
| Untreated | 8 | 0 | 0 | 0 | 0 | N/A | 0 | 0 | 0 |
| 20GyUniformRT | 8 | 20 | 20.8 | 20.8 | 19.9/20.1 | 1 | 20 | 20 | 100 |
| 20GyHalf-SFRT | 5 | 20 | 39 | 3.1 | 2.9/30.5 | 12.6 | 10 | 10 | 47.8(±2.2)d |
| 20Gy2mmSFRTc | 6 | 17.6b | 34.5 | 6.2 | 5.2/25.1 | 5.6 | 2 | 2.2 | 51.5(±11.6) |
| 20GySFRT | 9 | 20 | 91 | 6.8 | 5.3/47.4 | 13.3 | 0.9 | 0.31 | 20.3 |
| 50GySFRT | 6 | 50 | 225 | 16.8 | 13.1/117.3 |
a: Computed within 1cm depth (the tumor depth).
b: 17.63 Gy instead of the intended 20 Gy was used.
c: Dosimetric parameters for the 20Gy2mmSFRT arm were computed considering the maximum range of possible tumor positioning under the collimator.
d: Percentage volume irradiated for the 20GyHalfSFRT arm was computed using treatment verification film analysis of the irradiated tumors.
e: T/N in the table denotes Tumor EUD and normal tissue EUD. Tumor EUD is computed using a = -10 and a tumor size of 1cm in diameter. Normal tissue EUD is computed using a = 5 and a volume of 2cm in diameter. Note that tumor EUD is lower than valley surface dose is because the valley dose is measured at the surface while EUDs are computed using volumetric dose.
f: PVDR (peak-to-valley dose ratio) is the ratio of the peak dose to the valley dose.