Table 3.
OAR dosimetric parameters according to treatment techniques for all patients
| Target structure | Dosimetric parameter | nc-IMRTa | nc-VMATb | Hybrid IMRT/VMATc | Pairwise comparison P value |
|---|---|---|---|---|---|
| Spinal cord | Dmax (Gy) | 10.67 ± 4.06 | 10.2 ± 3.98 | 10.16 ± 3.69 | NS† |
| Brainstem | Dmax (Gy) | 17.93 ± 11.60 | 17.70 ± 12.36 | 17.73 ± 12.53 | NS† |
| Optic chiasm | Dmax (Gy) | 40.93 ± 9.31 | 39.63 ± 11.25 | 40.77 ± 9.03 | NS† |
| I/L optic nerve | Dmax (Gy) | 54.18 ± 0.56 | 54.0 ± 0.61 | 53.86 ± 0.68 | NS† |
| C/L optic nerve | Dmax (Gy) | 53.26 ± 2.63 | 52.25 ± 5.34 | 51.52 ± 4.37 | a versus c (0.042*) |
| I/L retina | Dmax (Gy) | 43.17 ± 3.10 | 43.02 ± 2.69 | 42.35 ± 2.64 | NS† |
| C/L retina | Dmax (Gy) | 40.42 ± 6.02 | 37.49 ± 8.66 | 37. 25 ± 8.07 | NS† |
| I/L cornea | Dmax (Gy) | 19.44 ± 6.32 | 17.80 ± 5.78 | 16.04 ± 5.27 | a versus c (0.055) |
| C/L cornea | Dmax (Gy) | 14.13 ± 5.56 | 12.21 ± 4.00 | 11.76 ± 2.85 | NS† |
| I/L lens | Dmax (Gy) | 8.45 ± 1.58 | 8.29 ± 1.67 | 7.84 ± 1.15 | NS† |
| C/L lens | Dmax (Gy) | 8.17 ± 1.81 | 7.54 ± 1.35 | 7.39 ± 1.62 | a versus c (0.08) |
| I/L lacrimal gland | Dmax (Gy) | 12.69 ± 4.80 | 12.92 ± 6.95 | 12.50 ± 6.52 | NS† |
| C/L lacrimal gland | Dmax (Gy) | 10.73 ± 2.21 | 12.09 ± 3.70 | 10.19 ± 2.97 | b versus c (0.021*) |
| I/L cochlea | Dmean (Gy) | 14.53 ± 7.58 | 15.90 ± 7.35 | 14.53 ± 6.74 | b versus c (0.020*) |
| C/L cochlea | Dmean (Gy) | 9.67 ± 7.83 | 11.19 ± 7.02 | 10.31 ± 6.36 | a versus b (0.099) |
| Brain | D0.5cc (Gy) | 66.20 ± 1.38 | 66.07 ± 1.37 | 65.67 ± 1.80 | NS† |
| Hippocampus | V7.2Gy (%) | 24.02 ± 8.74 | 23.84 ± 9.21 | 19.66 ± 11.61 | NS† |
| Integral dose | Gy l–1 | 49.88 ± 10.73 | 49.31 ± 12.22 | 48.40 ± 11.97 | NS† |
| Monitor units | MUs | 752.13 ± 48.11 | 565.89 ± 88.97 | 744.49 ± 127.44 | a versus b (<0.001*) b versus c (<0.001*) |
| Treatment time | Min | 1.25 ± 0.08 | 2.16 ± 0.02 | 2.04 ± 0.15 | a versus b (<0.001*) a versus c (0.002*) |
OAR = organs at risk; D(X% or cc) = dose (Gy) received by (X% or X ml) of structure; V(X% or XGy) = percentage volume of structure receiving dose (X% or X Gy) or more; I/L = ipsilateral; C/L = contralateral; NS = non-significant; Dmax = the maximum dose reported as the dose received by 0 ml of the volume of interest; Dmean = the mean dose received by the volume of interest.
*Significant (P < 0.05).
† P > 0.1.