CT ventilation image-guided helical Tomotherapy at sparing functional lungs for locally advanced lung cancer: analysis of dose-function metrics and the impact on pulmonary toxicity

Table 3 Summary of ROI-based lung DVH metrics, functional map-based DFH metrics and DFH metrics-based Normal tissue complication probabilities (NTCP) for grade 2 + radiation pneumonitis (RP) among RP-risk non-benefit patients (Group 2)

Variable	Planning strategy
Variable	Anatomical plan	Func_ plan _Top10	Func_ plan _Top20	Func_ plan _Top30	Func_ plan _Top40	Func_ plan _Top50
DFH metric-based NTCP model (toxicity probability of the mean)
NTCP_f _V10(%)	20.24 ± 14.68	26.21 ± 20.02	26.81 ± 22.08	23.56 ± 17.25	22.40 ± 16.87	21.47 ± 15.15
Ventilation map-based lung DFH metrics (mean values)
fV5 (%)	44.26 ± 20.54	52.89 ± 24.78	51.77 ± 25.62	49.96 ± 25.14	46.18 ± 23.29	44.84 ± 21.51
fV10(%)	27.36 ± 13.94	33.21 ± 17.58	33.52 ± 19.05	30.89 ± 15.79	29.77 ± 15.44	29.00 ± 14.46
fV20 (%)	16.72 ± 10.59	17.44 ± 12.55	17.25 ± 11.90	17.09 ± 11.46	16.53 ± 10.97	16.49 ± 10.66
fMLD (Gy)	5.59 ± 2.76	6.13 ± 3.05	6.16 ± 3.23	6.00 ± 3.06	5.82 ± 2.93	5.76 ± 2.82
Structure-based lung DVH metrics (mean values)
V5 (%)	41.14 ± 16.31	48.81 ± 16.53	47.44 ± 17.12	45.74 ± 16.06	43.12 ± 15.94	42.55 ± 16.42
V10(%)	25.10 ± 9.74	31.38 ± 13.44	31.56 ± 14.09	29.75 ± 11.59	28.15 ± 11.34	27.26 ± 10.29
V20 (%)	14.48 ± 6.90	15.05 ± 6.83	15.63 ± 8.20	15.15 ± 7.80	14.99 ± 8.49	14.81 ± 7.84
MLD (Gy)	8.52 ± 3.30	9.41 ± 3.42	9.54 ± 3.86	9.28 ± 3.66	9.18 ± 3.81	9.06 ± 3.66

^*p < 0.05 and **p < 0.01, indicate significantly decreased when compared with anatomical plan; Func_plan _{Top10/20/30/40/50}, means top 10%/20%/30%/40%/50% percentile functional volume were defined as the high-functional lung in planning optimization

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