Table 9.
Comparison of organs at risk (priority level I and II) in T3-4 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) | 54.26 (51.68-56.47) | 55.50 (51.27-58.72) | 52.50 (48.36-55.46) | 0.005 | 0.495 | 0.192 | 0.004 |
| Brain stem_PRV | D0.03cc (Gy) | 56.99 (54.26-63.71) | 62.13 (54.95-64.87) | 60.21 (55.83-64.81) | 0.867 | _ | _ | _ |
| Optic chiasm | Dmax (Gy) | 44.79 (37.66-48.40) | 41.65 (31.82-49.91) | 45.82 (34.86-48.35) | 0.717 | _ | _ | _ |
| Optic chiasma_PRV | D0.03cc (Gy) | 53.12 (45.23-55.99) | 50.96 (47.05-57.14) | 54.13 (46.59-56.64) | 0.538 | _ | _ | _ |
| Optic nerves_L | Dmax (Gy) | 38.28 (27.50-45.20) | 37.43 (27.82-45.55) | 42.61 (37.29-44.40) | 0.06 | _ | _ | _ |
| Optic nerves_L PRV | D0.03cc (Gy) | 46.24 (33.09-52.49) | 45.42 (35.24-56.66) | 51.90 (46.09-54.34) | 0.005 | 1 | 0.041 | 0.006 |
| Optic nerves_R | Dmax (Gy) | 40.45 (25.32-50.77) | 39.24 (27.17-49.94) | 43.89 (35.92-50.30) | 0.156 | _ | _ | _ |
| Optic nerves_R PRV | D0.03cc (Gy) | 47.91 (35.70-57.67) | 49.90 (39.98-56.14) | 53.11 (45.32-54.95) | 0.129 | _ | _ | _ |
| Spinal cord | Dmax (Gy) | 39.34 (38.42-40.50) | 41.84 (39.15-43.69) | 37.00 (32.38-40.78) | 0.001 | 0.092 | 0.269 | <0.001 |
| Spinal cord_PRV | D0.03cc (Gy) | 45.38 (41.93-49.18) | 46.66 (43.71-51.37) | 44.76 (41.06-52.05) | 0.467 | _ | _ | _ |
| Temporal lobe_L | Dmax (Gy) | 77.01 (76.41-78.28) | 78.06 (75.01-80.22) | 75.54 (73.77-76.74) | 0.002 | 1 | 0.016 | 0.004 |
| Temporal lobe_L PRV | D0.03cc (Gy) | 76.95 (76.26-77.96) | 78.27 (75.73-80.28) | 75.73 (74.91-77.05) | 0.003 | 0.84 | 0.076 | 0.003 |
| Temporal lobe_R | Dmax (Gy) | 77.46 (77.06-79.48) | 77.75 (75.42-80.80) | 75.40 (74.56-77.26) | 0.001 | 1 | 0.004 | 0.004 |
| Temporal lobe_R PRV | D0.03cc (Gy) | 77.55 (77.02-78.91) | 79.02 (75.82-80.54) | 75.48 (74.58-77.19) | 0.013 | 1 | 0.033 | 0.033 |
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.