| S1-S5 | first to fifth sacral nerves |
|---|---|
| CTV | cervical and thoracic vertebrae; clinical target volume |
| D3-12 | third to twelfth dorsal vertebrae |
| L1, | L2, L3, L4, L5 first, second, third, fourth, and fifth lumbar vertebrae |
| T1-T12 | first to twelfth thoracic vertebrae |