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Table 2 Comparison of PTV doses among the three techniques

From: Advanced nasopharyngeal carcinoma radiotherapy with volumetric modulated arcs and the potential role of flattening filter-free beams

Target RA-FFF RA IMRT p value p 1 p 2 p 3
PTV70        
D99%(Gy) 68.52 ± 0.46 68.69 ± 0.59 69.06 ± 0.22 0.122
D1%(Gy) 75.40 ± 1.32 74.08 ± 1.12 74.30 ± 0.62 0.007 0.005 0.028 0.878
Dmean(Gy) 72.80 ± 0.72 72.15 ± 0.68 71.95 ± 0.21 0.007 0.005 0.012 0.333
V70(%) 95.00 ± 0.00 95.00 ± 0.00 95.00 ± 0.00
CI 0.486 ± 0.213 0.609 ± 0.199 0.519 ± 0.220 0.014 0.007 0.445 0.037
HI 0.087 ± 0.023 0.067 ± 0.021 0.069 ± 0.011 0.008 0.005 0.028 0.646
PTV66        
D99%(Gy) 65.26 ± 0.99 65.19 ± 0.98 66.07 ± 1.09 0.121
D1%(Gy) 72.74 ± 1.58 71.34 ± 1.46 72.25 ± 1.53 0.008 0.008 0.314 0.799
Dmean(Gy) 69.67 ± 0.99 68.90 ± 0.85 70.18 ± 1.18 0.001 0.008 0.155 0.008
V66(%) 97.65 ± 1.28 97.53 ± 1.37 99.08 ± 0.60 0.050
CI 0.209 ± 0.074 0.244 ± 0.074 0.226 ± 0.083 0.169
HI 0.108 ± 0.054 0.088 ± 0.052 0.080 ± 0.048 0.001 0.008 0.008 0.123
PTV60        
D99%(Gy) 57.97 ± 0.84 57.88 ± 0.77 58.54 ± 0.71 0.006 0.508 0.009 0.009
D1%(Gy) 74.31 ± 1.08 73.38 ± 1.02 73.30 ± 0.61 0.025 0.009 0.022 0.799
Dmean(Gy) 66.23 ± 0.93 65.55 ± 1.08 66.47 ± 0.91 0.001 0.005 0.333 0.005
V60(%) 96.36 ± 0.87 96.13 ± 0.95 97.88 ± 0.44 0.002 0.445 0.005 0.007
CI 0.793 ± 0.025 0.811 ± 0.023 0.813 ± 0.025 0.002 0.005 0.022 0.575
HI 0.230 ± 0.040 0.217 ± 0.044 0.199 ± 0.038 0.001 0.047 0.005 0.005
  1. Abbreviations: CI = conformity index; HI = homogeneity index; D 99%  = dose received by 99% of the volume; p1 = Wilcoxon test p value between RA-FFF and RA plans; p2 = Wilcoxon test p value between RA-FFF and IMRT plans; p3 = Wilcoxon test p value between RA and IMRT plans. Other abbreviations as in Table 1.