Dosimetry and efficiency comparison of knowledge-based and manual planning using volumetric modulated arc therapy for craniospinal irradiation

Tsai, Wei-Ta; Hsieh, Hui-Ling; Hung, Shih-Kai; Zeng, Chi-Fu; Lee, Ming-Fen; Lin, Po-Hao; Lin, Chia-Yi; Li, Wei-Chih; Chiou, Wen-Yen; Wu, Tung-Hsin

doi:10.2478/raon-2024-0018

Figures & Tables

Flowchart of the study design.CSI = craniospinal irradiation; CT = computed tomography; KBP = knowledge-based planning; VMAT = volumetric modulated arc therapy

Example of the target and field setup. (A) The arrangement of the brain field (dotted lines), spine-superior field (solid lines), spine-inferior field (dashed lines), and their isocenters. Each field overlaps at least 5 cm for the low-dose gradient junction. (B) Full arc was used on the brain field. (C) Partial arc was used in the spinal fields for arm sparing.

(A) Population-averaged dose-volume histogram (DVH) for all organs at risk and targets. (B) The population-averaged DVH for targets only.CTV = clinical target volume; MP = manual optimization plan; PTV = planning target volumes; RPI = RapidPlan initial; RPF = final RapidPlan after manual re-optimization

Comparison of the planning time for MP, RPI, and RPF. The error bar represents one standard deviation.MP = manual optimization plan; RPI = RapidPlan initial; RPF = final RapidPlan after manual re-optimization

Dosimetric goals and results for organs at risk

OAR parameters	Goals	Results			*P value*

		MP	RP_I	RP_F	*MP vs.* RP_F**	*MP vs.* RP_F**	*RP_I vs.* RP_I**
Brain
D_max [Gy]	< 60	39.34 ± 0.39	40.24 ± 0.61	39.28 ± 0.37	< 0.01^**	0.46	< 0.01^**
Brain stem
D_max [Gy]	< 54	38.48 ± 0.41	39.03 ± 0.46	38.51 ± 0.28	< 0.01^**	0.91	< 0.01^**
Chiasm
D_mean [Gy]	< 50	37.15 ± 0.35	37.10 ± 0.32	36.95 ± 0.32	0.69	0.07	0.06
D_max [Gy]	< 55	38.13 ± 0.40	38.73 ± 0.55	38.20 ± 0.26	0.01^*	0.46	< 0.01^**
Optic nerves
D_mean [Gy]	< 50	27.61 ± 3.40	22.90 ± 2.39	22.42 ± 2.29	< 0.01^**	< 0.01^**	0.05
D_max [Gy]	< 55	37.13 ± 0.69	36.36 ± 1.72	36.15 ± 1.39	0.13	0.02^*	0.13
Eyes
D_max [Gy]	< 50	25.55 ± 3.57	22.52 ± 3.83	21.60 ± 3.86	0.02^*	0.01^*	0.01^*
Lens
D_max [Gy]	< 10	8.40 ± 0.68	8.87 ± 1.00	8.10 ± 0.55	0.11	0.21	< 0.01^**
Parotid glands
D_mean [Gy]	< 25	7.38 ± 2.52	5.16 ± 0.39	4.95 ± 0.39	< 0.01^**	< 0.01^**	< 0.01^**
Spinal cord
D_max [Gy]	< 50	38.93 ± 0.51	39.81 ± 0.67	39.04 ± 0.56	< 0.01^**	< 0.01^**	< 0.01^**
Thyroid
D_max [Gy]	< 45	17.23 ± 4.04	16.68 ± 2.13	16.38 ± 2.04	0.59	0.36	0.07
Lungs
D_mean [Gy]	< 13	4.63 ± 0.30	4.95 ± 0.43	4.63 ± 0.24	0.03^*	0.73	< 0.01^**
V_20Gy [%]	< 22	0.06 ± 0.11	0.04 ± 0.08	0.03 ± 0.04	0.64	0.44	0.33
V_5Gy [%]	< 42	36.48 ± 2.88	42.77 ± 5.62	37.11 ± 2.87	0.01^*	0.69	< 0.01^**
Heart
D_mean [Gy]	< 10	6.76 ± 1.47	5.53 ± 0.82	5.70 ± 0.93	0.01^*	0.02^*	0.33
V_40Gy [%]	< 3	0.00 ± 0.00	0.00 ± 0.00	0.00 ± 0.00	-	-	-
V_18Gy [%]	< 5	0.04 ± 0.10	0.01 ± 0.03	0.01 ± 0.02	0.31	0.23	0.41
Esophagus
D_mean [Gy]	< 34	14.34 ± 1.62	13.23 ± 1.63	13.30 ± 1.74	0.01^*	< 0.01^**	0.96
Liver
D_mean [Gy]	< 30	4.82 ± 0.94	4.57 ± 0.73	4.45 ± 0.70	0.61	0.33	< 0.01^**
Kidneys
D_mean [Gy]	< 18	2.81 ± 1.17	2.47 ± 0.46	2.38 ± 0.43	0.96	0.73	< 0.01^**

The mean dose of the OARs outside the targets contours

Organ	Mean dose			*P value*

	MP	RP_I	RP_F	*MP vs.* RP_I**	*MP vs.* RP_F**	*RP_I vs.* RP_F**
Optic nerves	27.61 ± 3.40	22.90 ± 2.39	22.42 ± 2.29	< 0.01^**	< 0.01^**	0.05
Eyes	12.11 ± 1.99	10.16 ± 0.55	9.83 ± 0.74	0.01^*	0.01^*	0.02^*
Lens	7.09 ± 0.67	7.21 ± 0.52	6.78 ± 0.39	0.43	0.16	< 0.01^**
Parotid glands	7.38 ± 2.52	5.16 ± 0.39	4.95 ± 0.39	< 0.01^**	< 0.01^**	< 0.01^**
Thyroid	10.41 ± 3.37	9.00 ± 1.94	8.51 ± 2.07	0.06	0.04^*	< 0.01^**
Lungs	4.63 ± 0.30	4.95 ± 0.43	4.63 ± 0.24	0.03^*	0.73	< 0.01^**
Heart	6.76 ± 1.47	5.53 ± 0.82	5.70 ± 0.93	0.01^*	0.02^*	0.33
Liver	4.82 ± 0.94	4.57 ± 0.73	4.45 ± 0.70	0.61	0.33	< 0.01^**
Kidneys	2.81 ± 1.17	2.47 ± 0.46	2.38 ± 0.43	0.96	0.73	< 0.01^**

Dosimetric comparison between manual plans, RapidPlan initial, and RapidPlan final

Parameters	Goals	Results			*P value*

		MP	RP_I	RP_F	*MP vs.* RP_I**	*MP vs.* RP_F**	*RP_I vs.* RP_F**
CTV
V₉₅ [%]	> 99	99.99 ± 0.03	99.98 ± 0.03	99.97 ± 0.03	0.36	0.03^*	0.09
V₁₀₀ [%]	> 99	99.20 ± 0.17	98.37 ± 0.33	99.37 ± 0.23	< 0.01^**	0.07	< 0.01^**
V₁₀₇ [%]	Minimize	0.62 ± 0.59	2.94 ± 4.33	0.46 ± 0.66	< 0.01^**	0.16	< 0.01^**
D_mean [Gy]	36	37.23 ± 0.18	37.31 ± 0.21	37.22 ± 0.24	0.07	0.87	0.13
D_max [Gy]	Minimize	39.38 ± 0.40	40.38 ± 0.57	39.42 ± 0.41	< 0.01^**	0.78	< 0.01^**
D₂ [%]	< 107	106.12 ± 0.73	106.95 ± 0.96	105.72 ± 0.84	< 0.01^**	0.19	< 0.01^**
PTV
V₉₅ [%]	> 98	99.68 ± 0.15	99.55 ± 0.23	99.24 ± 0.32	0.03^*	< 0.01^**	< 0.01^**
V₁₀₀ [%]	= 95	95.00 ± 0.00	95.00 ± 0.00	95.00 ± 0.00	-	-	-
V₁₀₇ [%]	Minimize	0.62 ± 0.57	3.01 ± 4.12	0.44 ± 0.61	< 0.01^**	0.17	< 0.01^**
D_mean [Gy]	36	37.10 ± 0.16	37.22 ± 0.18	37.08 ± 0.20	0.05	0.73	0.01^*
D_max [%]	< 112	109.99 ± 1.17	112.89 ± 1.78	110.17 ± 1.14	< 0.01^**	0.57	< 0.01^**
D₂ [%]	< 107	106.09 ± 0.73	107.00 ± 0.93	105.71 ± 0.80	< 0.01^**	0.21	< 0.01^**
CI	1	0.98 ± 0.01	1.01 ± 0.01	1.00 ± 0.01	< 0.01^**	< 0.01^**	0.01^*
HI	1	1.10 ± 0.01	1.13 ± 0.02	1.10 ± 0.01	< 0.01^**	0.57	< 0.01^**

Dosimetry and efficiency comparison of knowledge-based and manual planning using volumetric modulated arc therapy for craniospinal irradiation

Figures & Tables

FIGURE 1.

FIGURE 2.

FIGURE 3.

FIGURE 4.

Dosimetric goals and results for organs at risk

The mean dose of the OARs outside the targets contours

Dosimetric comparison between manual plans, RapidPlan initial, and RapidPlan final

Paradigm

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