Table 2 Comparison of dosimetric values of the original and re-optimized plans

Left cochlea Dmean

24.09 Gy (range 12.52–68.45 Gy)

14.97 Gy (range 7.31–67.48 Gy)

< 0.001

Right Cochlea Dmean

26.05 Gy (range 14.46–60.53 Gy)

18.47 Gy (range 8.37–60.14 Gy)

< 0.001

Left Cochlea Dmax

32.12 Gy (range 22.75–70.66 Gy)

24.64 Gy (range 10.86–69.8 Gy)

< 0.001

Right cochlea Dmax

41.47 Gy (range 21.29–67.87 Gy)

33.66 Gy (range 12.28–69.05 Gy)

0.001

PTV Dmean

69.96 Gy (range 66.00–70.42 Gy)

69.96 Gy (range 66.00–71.23 Gy)

0.201

PTV HI

0.095 (range 0.05–0.14)

0.070 (range 0.04–0.13)

0.001

PTV CI

0.595 (range 0.51–0.77)

0.595 (range 0.54–0.79)

0.046

PTV D2%

72.47 Gy (range 69.35–73.65 Gy)

71.98 Gy (range 67.86–73.54 Gy)

0.001

PTV D98%

65.99 Gy (range 62.91–68.75 Gy)

66.85 Gy (range 62.94–68.97 Gy)

< 0.001

PTV V95%

97.49% (range 92.73–99.8%)

98.73% (range 94.3–100%)

0.001

Brainstem Dmax

50.59 Gy (range 20.23–62.57 Gy)

50.81 Gy (range 20.38–64.96 Gy)

0.965

Left parotis Dmean

24.95 Gy (range 14.49–62.21 Gy)

23.68 Gy (range 14.53–61.61 Gy)

0.024

Right parotis Dmean

24.59 Gy (range 16.94–50.4 Gy)

21.92 Gy (range 15.43–50.4 Gy)

0.009

Spinal cord Dmax

40.27 Gy (range 33.69–54.01 Gy)

38.99 Gy (range 33.45–54.04 Gy)

0.011

Oral cavity Dmean

30.41 Gy (range 22.74–44.03 Gy)

31.56 Gy (range 23.16–42.41 Gy)

0.452

Mandible Dmean

30.03 Gy (range 21.16–37.37 Gy)

30.46 Gy (range 20.97–36.96 Gy)

0.985

Mandible V70Gy

0.000 (range 0–0.258)

0.000 (range 0–0.246)

0.789

Chiasm Dmax

10.70 Gy (range 3.12–60.23 Gy)

9.21 Gy (range 3.14–60.23 Gy)

0.231

Chiasm D0.03 cc

8.68 cc (range 2.99–57.17 cc)

7.33 cc (range 3.03–67.67 cc)

0.956

Left optic nerve D0.03 cc

12.94 cc (range 2.51–70.16 cc)

9.58 cc (range 2.48–69.81)

0.076

Right optic nerve D0.03 cc

17.35 cc (range 2.86–58.31 cc)

12.71 cc (range 2.86–57.06)

0.007

NTCP tinnitus

11.33% (range 3.52–91.10%)

4.60% (range 1.46–90.10%)

< 0.001

NTCP hearing loss

0.03% (range 0.00–98.97%)

0.00% (range 0.00–98.54%)

< 0.001