Table 3. Dose comparison of OARs for two plans.
| Indices | RapidArc | IMRT | P |
|---|---|---|---|
| Spinal cord Dmean (Gy) | 27.7±1.4 | 27.8±1.7 | >0.05 |
| Spinal cord Dmax (Gy) | 33.7±1.7 | 33.5±1.2 | >0.05 |
| Brain stem Dmean (Gy) | 23.9±2.8 | 27.9±2.2 | <0.05 |
| Brain stem Dmax (Gy) | 45.2±2.4 | 43.6±1.7 | <0.05 |
| Mandible Dmean (Gy) | 46.6±2.5 | 50.5±2.1 | <0.05 |
| Mandible Dmax (Gy) | 73.8±1.8 | 74.0±2.1 | >0.05 |
| Left lens Dmean (Gy) | 5.3±0.5 | 5.4±0.7 | >0.05 |
| Left lens Dmax (Gy) | 6.2±0.5 | 6.2±0.7 | >0.05 |
| Right lens Dmean (Gy) | 5.3±0.4 | 5.2±0.6 | >0.05 |
| Right lens Dmax (Gy) | 6.2±0.4 | 6.4±0.7 | >0.05 |
| Left optic nerve Dmean (Gy) | 32.8±5.2 | 37.6±4.9 | <0.05 |
| Left optic nerve Dmax (Gy) | 53.5±4.2 | 55.6±3.0 | <0.05 |
| Right optic nerve Dmean (Gy) | 32.9±5.6 | 37.6±4.6 | <0.05 |
| Right optic nerve Dmax (Gy) | 51.6±8.9 | 55.1±2.6 | >0.05 |
The Dmean of RapidArc for the brain stem was really lower than that of IMRT. As was shown above, the Dmean and the Dmax for the left optic nerve of RapidArc were really lower than that of IMRT. For the Dmean of the mandible, RapidArc was also lower than IMRT (P<0.05).