Table 4.
Percent changes for mean tumor doses at the BMRR and the THOR with lateral shifts of a patient head model parallel to the beam port collimator surface or with an air gap between the patient head model and the beam port due to an outward shift of the head.
| Distance and type of shift | BMRR (%) [3] | THOR (%) | |||
|---|---|---|---|---|---|
| Model | Cylindrical | ||||
| T6.5cm | T2.5cm | T6.5cm | T2.5cm | ||
| 1 cm lateral shift | 2.78 | 1.43 | 0.63 | 1.48 | 0.87 |
| 2 cm lateral shift | 7.19 | 5.52 | 3.63 | 5.31 | 4.11 |
| 3 cm lateral shift | - | 11.12 | 8.85 | 11.31 | 9.38 |
| 1 cm outward shift | 9.03 | 4.70 | 4.74 | 4.72 | 4.25 |
| 2 cm outward shift | 15.56 | 10.67 | 8.51 | 11.85 | 10.92 |
| 3 cm outward shift | - | 15.17 | 12.57 | 16.87 | 15.32 |