Table 1.
Comparison of percentage depth dose parameters for 6-MV photon beam
| Field size (cm×cm) | Field defining method | Percentage depth dose (%) | Depth of 80% dose (mm) | Quality index | |||
|---|---|---|---|---|---|---|---|
| Dmax | D-0 | D-100 | D-200 | (Ql) | |||
| Jaw only | 16 | 46.97 | 63.29 | 34.81 | 61.22 | 0.6344 | |
| 5×5 | MLC only | 16 | 46.98 | 63.39 | 34.66 | 60.12 | 0.6302 |
| Jaw+MLC | 16 | 44.41 | 63.68 | 35 | 60.97 | 0.6341 | |
| Jaw only | 16 | 50.84 | 67.1 | 38.52 | 65.86 | 0.6664 | |
| 10×10 | MLC only | 16 | 51.37 | 67.04 | 38.62 | 65.65 | 0.6693 |
| Jaw+MLC | 18 | 48.94 | 66.94 | 38.5 | 66.19 | 0.668 | |
| Jaw only | 16 | 59.02 | 70.3 | 42.76 | 71.67 | 0.7115 | |
| 20×20 | MLC only | 16 | 60.41 | 69.65 | 42.82 | 69.37 | 0.7201 |
| Jaw+MLC | 17 | 57.33 | 69.95 | 42.85 | 72.1 | 0.7172 | |
| Jaw only | 14 | 65.4 | 71.05 | 44.8 | 73.08 | 0.7402 | |
| 30×30 | MLC only | 12 | 66.68 | 71.32 | 44.72 | 74.68 | 0.7357 |
| Jaw+MLC | 16 | 63.8 | 71.26 | 44.78 | 73.7 | 0.7374 | |