Estimation of radiotherapy modalities for patients with stage I-II nasal natural killer T-Cell lymphoma

Figures & data

Figure 1 Example of the dose distribution using IMRT, TD, VMAT and TH for the same patient.

Abbreviations: IMRT, intensity-modulated radiotherapy; TD, TomoDirect; VMAT, volumetric modulated arc therapy; TH, TomoHelical.

Figure 2 DVH for (A) IMRT, (B) TD, (C) VMAT and (D) TH plans for the same patient.

Abbreviations: DVH, Dose–Volume Histogram; IMRT, intensity-modulated radiotherapy; TD, TomoDirect; VMAT, volumetric modulated arc therapy; TH, TomoHelical.

Table 1 All the parameters utilized in EAR calculations in this study

Site	βEAR	γe	γa	α	α/β	R
Oropharynx	0.56	−0.024	2.38	0.043	10	0.97
Thyroid	1.2	−0.046	0.6	0.033	3	0.5
Salivary gland	0.56	−0.024	2.38	0.087	3	0.23

Abbreviation: EAR, excess absolute risk.

Table 2 Results of dosimetric comparison for PTV from DVH ($\bar{\mathrm{x}}\pm \mathrm{S}$)

Parameters	IMRT	TD	VMAT	TH	p-value
IMRT vs TD	IMRT vs VMAT	IMRT vs TH	TD vs VMAT	TD vs TH	VMAT vs TH
D98% (Gy)	46.86±0.15	48.91±0.06	47.72±0.15	48.92±0.08	0.000	0.000	0.000	0.000	0.914	0.000
D2% (Gy)	53.34±0.07	52.80±0.09	53.33±0.10	52.38±0.10	0.000	0.951	0.000	0.003	0.007	0.000
Dmean (Gy)	51.21±0.09	45.84±0.52	51.39±0.12	46.47±0.49	0.000	0.165	0.000	0.000	0.036	0.000
V95%(%)	99.96±0.22	99.16±0.07	98.06±0.23	99.30±0.08	0.000	0.000	0.000	0.000	0.044	0.000
Cold spot volume (%)	1.68±0.16	0.53±0.06	0.78±0.13	0.39±0.06	0.000	0.000	0.000	0.103	0.011	0.021
CI	0.905±0.004	0.830±0.007	0.920±0.004	0.850±0.008	0.000	0.003	0.000	0.000	0.004	0.000
HI	0.091±0.002	0.058±0.002	0.084±0.002	0.051±0.002	0.000	0.010	0.000	0.000	0.025	0.000
MUs	1191.08±32.55	3415.33±96.27	451.42±19.11	3441.42±93.43	0.000	0.000	0.000	0.000	0.363	0.000
Time (s)	421.66±4.76	327.10±6.61	189.27±1.29	245.46±6.40	0.000	0.000	0.000	0.000	0.000	0.000

Abbreviations: PTV, planning target volume; DVH, Dose–Volume Histogram; IMRT, intensity-modulated radiotherapy; TD, TomoDirect; VMAT, volumetric modulated arc therapy; TH, TomoHelical; HI, homogeneity index; CI, conformity index; MUs, monitor units.

Table 3 Results of dosimetric comparisons for OARs from DVH ($\bar{\mathrm{x}}\pm \mathrm{S}$)

Parameters		IMRT	TD	VMAT	TH	p-value
IMRT vs TD	IMRT vs VMAT	IMRT vs TH	TD vs VMAT	TD vs TH	VMAT vs TH
Optic chiasm	Dmax (Gy)	41.50±1.40	45.69±1.45	42.10±1.42	45.02±1.31	0.000	0.030	0.000	0.000	0.181	0.000
	Dmean (Gy)	30.43±1.10	34.25±11.13	31.26±1.04	34.24±1.02	0.000	0.027	0.000	0.000	0.990	0.000
Left optic nerve	Dmax (Gy)	46.48±1.38	51.21±0.07	47.00±1.45	49.98±0.08	0.000	0.218	0.001	0.000	0.002	0.002
	Dmean (Gy)	35.08±1.09	44.65±0.09	38.35±1.37	43.78±1.07	0.000	0.000	0.000	0.000	0.205	0.000
Right optic nerve	Dmax (Gy)	46.80±1.04	50.85±0.53	46.86±1.12	49.81±0.46	0.000	0.820	0.000	0.000	0.026	0.001
	Dmean (Gy)	35.46±1.32	42.86±0.92	37.26±1.30	41.91±0.96	0.000	0.002	0.000	0.000	0.137	0.000
Left eye	Dmax (Gy)	47.55±1.28	48.57±0.83	48.32±1.23	49.07±0.97	0.171	0.161	0.066	0.703	0.215	0.238
	Dmean (Gy)	21.63±0.83	26.91±0.59	21.09±0.88	27.44±0.57	0.000	0.273	0.000	0.000	0.251	0.000
Right eye	Dmax (Gy)	43.75±1.72	46.07±1.23	45.74±1.33	46.68±1.05	0.028	0.019	0.014	0.637	0.277	0.323
	Dmean (Gy)	21.47±1.41	25.09±0.68	19.42±0.93	25.70±0.61	0.012	0.124	0.008	0.000	0.056	0.000
Left lens	Dmax (Gy)	12.66±0.33	10.29±0.60	10.95±0.29	14.33±0.62	0.001	0.000	0.021	0.277	0.000	0.000
	Dmean (Gy)	10.13±0.27	7.47±0.38	8.57±0.24	10.18±0.40	0.000	0.000	0.908	0.015	0.000	0.001
Right lens	Dmax (Gy)	12.50±0.57	9.11±0.63	10.91±0.44	12.68±0.81	0.000	0.001	0.818	0.011	0.000	0.035
	Dmean (Gy)	9.93±0.38	6.66±0.41	8.56±0.34	8.87±0.53	0.000	0.000	0.061	0.001	0.000	0.639
Spinal cord	Dmax (Gy)	11.79±1.93	17.86±2.00	12.10±1.88	16.99±1.85	0.000	0.559	0.000	0.000	0.035	0.000
	Dmean (Gy)	1.17±0.22	8.97±1.00	1.46±0.30	8.53±0.93	0.000	0.003	0.000	0.000	0.035	0.000
Brainstem	Dmax (Gy)	35.20±1.07	36.10±1.29	33.60±1.24	32.40±1.63	0.313	0.013	0.014	0.001	0.000	0.145
	Dmean (Gy)	23.64±0.82	23.06±0.91	23.31±0.82	21.75±1.10	0.328	0.338	0.012	0.621	0.001	0.024
Left parotid	Dmax (Gy)	24.01±1.98	24.13±1.72	21.94±1.73	23.64±1.52	0.909	0.021	0.753	0.036	0.538	0.045
	Dmean (Gy)	6.45±0.98	12.59±0.92	6.48±0.89	12.62±0.87	0.000	0.878	0.000	0.000	0.943	0.000
Right parotid	Dmax (Gy)	21.97±2.02	21.13±1.80	19.79±1.95	21.25±1.79	0.416	0.020	0.489	0.125	0.811	0.031
	Dmean (Gy)	6.41±1.15	11.20±0.98	6.57±1.05	11.27±0.99	0.000	0.396	0.000	0.000	0.809	0.000
Oropharynx	Dmax (Gy)	32.68±3.78	42.15±2.21	33.46±3.70	42.52±2.12	0.000	0.242	0.000	0.000	0.444	0.000
	Dmean (Gy)	6.22±1.08	21.72±1.16	7.20±1.18	21.79±1.09	0.000	0.000	0.000	0.000	0.808	0.000
Thyroid	Dmax (Gy)	0.34±0.03	0.39±0.02	0.38±0.03	0.39±0.03	0.000	0.000	0.000	0.330	0.994	0.286
	Dmean (Gy)	0.17±0.02	0.26±0.01	0.21±0.01	0.27±0.02	0.000	0.000	0.000	0.000	0.305	0.000
Left salivary	Dmax (Gy)	1.43±0.12	3.21±1.04	1.95±0.21	3.18±0.92	0.076	0.001	0.046	0.177	0.828	0.129
	Dmean (Gy)	0.88±0.07	2.29±0.61	1.18±0.11	1.94±0.47	0.022	0.000	0.020	0.064	0.327	0.076
Right salivary	Dmax (Gy)	1.50±0.21	3.34±0.98	1.97±0.21	3.26±0.97	0.027	0.000	0.032	0.112	0.515	0.131
	Dmean (Gy)	1.14±0.24	2.00±0.51	1.41±0.25	1.97±0.51	0.089	0.424	0.099	0.204	0.609	0.227

Abbreviations: OARs, organs at risk; DVH, Dose–Volume Histogram; IMRT, intensity-modulated radiotherapy; TD, TomoDirect; VMAT, volumetric modulated arc therapy; TH, TomoHelical.

Table 4 The EAR of oropharynx, thyroid, left and right salivary gland with four treatment modalities

EAR	IMRT	TD	VMAT	TH	p-value
IMRT vs TD	IMRT vs VMAT	IMRT vs TH	TD vs VMAT	TD vs TH	VMAT vs TH
Oropharynx	1.47±0.20	2.70±0.29	1.69±0.22	2.68±0.28	0.000	0.000	0.000	0.000	0.607	0.000
Thyroid	0.11±0.02	0.15±0.02	0.13±0.02	0.15±0.02	0.002	0.000	0.001	0.077	0.989	0.045
Left salivary gland	0.31±0.03	0.43±0.05	0.40±0.04	0.44±0.05	0.000	0.000	0.000	0.050	0.669	0.052
Right salivary gland	0.31±0.03	0.42±0.04	0.40±0.04	0.42±0.04	0.000	0.000	0.000	0.045	0.832	0.031

Abbreviations: EAR, excess absolute risk; IMRT, intensity-modulated radiotherapy; TD, TomoDirect; VMAT, volumetric modulated arc therapy; TH, TomoHelical.