Table 6.
Comparison of organs at risk (priority level I and II) in T1-2 NPC patients.
| Median (IQR) | P-value | |||||||
|---|---|---|---|---|---|---|---|---|
| OAR | Objective | IMRT | VMAT | TOMO | P | I vs. V | I vs. T | V vs. T |
| Brain stem | Dmax (Gy) | 49.63 (47.56-54.50) | 50.92 (48.46-55.73) | 48.60 (41.52-53.40) | 0.04 | 0.871 | 0.035 | 0.023 |
| Brain stem_PRV | D0.03cc (Gy) | 52.87 (51.49-57.46) | 53.43 (51.97-58.76) | 56.67 (51.70-59.55) | 0.809 | _ | _ | _ |
| Optic chiasm | Dmax (Gy) | 10.00 (8.52-15.32) | 9.58 (8.14-12.47) | 20.88 (15.30-30.29) | <0.001 | 0.433 | 0.011 | <0.001 |
| Optic chiasma_PRV | D0.03cc (Gy) | 18.56 (12.59-25.25) | 18.31 (12.03-23.44) | 28.75 (23.77-40.12) | <0.001 | 0.433 | 0.002 | <0.001 |
| Optic nerves_L | Dmax (Gy) | 7.76 (5.89-10.51) | 7.69 (5.81-9.38) | 18.02 (13.90-21.37) | <0.001 | 1 | <0.001 | <0.001 |
| Optic nerves_L PRV | D0.03cc (Gy) | 11.80 (9.22-17.65) | 13.08 (8.86-16.17) | 24.80 (20.87-29.45) | 0.001 | 1 | 0.017 | 0.001 |
| Optic nerves_R | Dmax (Gy) | 7.84 (6.57-10.78) | 7.61 (6.78-11.29) | 17.05 (13.04-24.58) | <0.001 | 1 | 0.002 | 0.002 |
| Optic nerves_R PRV | D0.03cc (Gy) | 13.10 (9.76-20.09) | 12.11 (10.63-21.35) | 26.59 (20.93-31.58) | <0.001 | 0.991 | 0.011 | <0.001 |
| Spinal cord | Dmax (Gy) | 38.75 (37.77-40.18) | 39.66 (38.10-41.28) | 34.01 (32.42-37.72) | <0.001 | 1 | 0.001 | <0.001 |
| Spinal cord_PRV | D0.03cc (Gy) | 43.20 (42.35-44.90) | 43.16 (42.49-44.74) | 42.06 (39.82-44.09) | 0.018 | 1 | 0.069 | 0.028 |
| Temporal lobe_L | Dmax (Gy) | 64.87 (62.92-71.83) | 66.44 (61.54-70.85) | 64.21 (58.37-67.55) | 0.001 | 1 | 0.004 | 0.006 |
| Temporal lobe_L PRV | D0.03cc (Gy) | 71.21 (69.42-73.77) | 71.49 (67.84-73.06) | 68.95 (64.28-72.10) | 0.001 | 1 | 0.001 | 0.017 |
| Temporal lobe_R | Dmax (Gy) | 67.31 (62. 72-72.40) | 68.56 (61.94-71.97) | 64.80 (58.73-70.46) | 0.018 | 1 | 0.028 | 0.069 |
| Temporal lobe_R PRV | D0.03cc (Gy) | 72.31 (68.95-74.14) | 72.01 (67.95-73.21) | 71.60 (67.18-73.09) | 0.065 | _ | _ | _ |
IMRT/I, intensity modulated radiation therapy; VMAT/V, volumetric modulated arc therapy; TOMO/T, tomotherapy; OAR, organ at risk; IQR, inter-quartile range; Gy, gray; PRV, planning risk volume; L, left; R, right; Dmax, the maximum dose; D0.03cc, an approximate maximum dose for the organs at risk.