Table 1.
DVH Parameters and OAR Constraints
| Structure | DVH Parameter | Planning Constrainta |
| Optic Apparatus | Dmax | 10 Gyb |
| Optic Apparatus | V8Gy | - |
| Optic Apparatus | V6Gy | - |
| Brainstem | Dmax | - |
| Brainstem | D0.5cc | - |
| Brainstem | D1cc | 12 Gy |
| Brainstem | V12Gy | - |
| Brainstem | V10Gy | - |
| Cochlea | Dmax | 12 Gy |
| Cochlea | Dmean | - |
| Brain | V25%Rx | - |
Abbreviations: DVH = dose volume histogram; OAR = organs at risk; VXGy = volume of OAR receiving X Gy; Dmax = maximum point dose; Dmean = mean dose; DXcc = dose received by X cc volume of OAR; V25%Rx = volume receive 25% of prescription dose. a not used for VMAT if the risk structure was not too close and possible to achieve with the natural dose fall off. b 12 Gy was used for one patient.