Table 1.
Variation in the number of iso-centers and overall treatment times used on a series of patients with large Vestibular Schwannomas. The prescription dose varied between 14 and 10 Gy, delivered to the 40 – 60 % iso-dose using a Series-B Gamma Knife.
| Prescription dose (Gy)/ | Overall treatment time (min) | |||||||
| Iso-center number | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 | 80-90 | > 90 |
| 14 Gy | ||||||||
| 3 iso-centers (2 gaps* | 25.40 | - | ||||||
| 4 iso-centers (3 gaps) | - | 41.28 | - | |||||
| 5 iso-centers (4 gaps) | - | 40.28 | - | |||||
| 6 iso-centers (5 gaps) | - | 67.78 | - | |||||
| 13 iso-centers (12 gaps) | - | 129.58 | ||||||
| 13 Gy | ||||||||
| 3 iso-centers (2 gaps) | - | 54.55 | - | |||||
| 6 iso-centers (5 gaps) | - | 61.58 | 74.91 | - | ||||
| 7 iso-centers (6 gaps) | - | 74.89 | 84.61 | 91.96 | ||||
| 75.36 | - | 92.30 | ||||||
| 8 iso-centers (7 gaps) | - | 124.25 | ||||||
| 12 Gy | ||||||||
| 2 iso-centers (1 gap) | 29.62 | - | ||||||
| 4 iso-centers (3 gaps) | - | 32.65 | - | |||||
| 39.97 | ||||||||
| 5 iso-centers (4 gaps) | - | 50.47 | - | |||||
| 6 iso-centers (5 gaps) | - | 63.07 | 73.97 | - | ||||
| 7 iso-centers (6 gaps) | - | 80.38 | ||||||
| 8 iso-centers (7 gaps) | - | 63.43 | - | |||||
| 10 Gy | ||||||||
| 5 iso-centers (4 gaps) | - | 38.16 | - | |||||
| 6 iso-centers (5 gaps) | - | 49.79 | ||||||
| 7 iso-centers (6 gaps) | - | 57.21 | - | |||||
| 8 iso-centers (7 gaps) | - | 73.93 | - | |||||
*
Nominal gap period 6 min.