Comparing dose-volume histogram and radiobiological endpoints for ranking intensity-modulated arc therapy and 3D-radiotherapy treatment plans for locally-advanced pancreatic cancer

Figures & data

Table I. Comparison of DVH metrics for 3D-RT vs IMAT plans for cord, liver and kidney. For each dose constraint, the number of patients whose plans achieved the dose constraints is noted in brackets for each technique. PD = prescribed dose, NS = not significant.

Dosimetric constraints		3D-RT plans mean (Gy)± 1 SD	IMAT plans mean (Gy)± 1 SD	p-value
PTV1	D99% > 95% PD	CI95% = 1.64 ± 0.18	CI95% = 1.23 ± 0.08	< 0.0001
PTV2	Dmax ≤107% PD	CI95% = 1.83 ± 0.25	CI95% = 1.08 ± 0.03	< 0.0001
R kidney	D50% < 20 Gy	12.1 ± 5.4 (11/11)	14.1 ± 2.2 (11/11)	NS
L kidney	D30% < 20 Gy	19.5 ± 4.3 (6/11)	15.6 ± 2.0 (11/11)	0.04
Liver	D50% < 20 Gy	6.7 ± 5.1 (11/11)	7.2 ± 5.2 (11/11)	NS
Cord	D0.1cc < 40 Gy	35.4 ± 2.9 (11/11)	38.3 ± 0.7 (11/11)	0.008
Stomach wall	D2% < 60 Gy	59.5 ± 2.2 (4/11)	57.7 ± 3.8 (9/11)	NS
	D15% < 45 Gy	44.3 ± 11.3 (4/11)	40.6 ± 11.6 (6/11)	0.007
Duodenum	D2% < 60 Gy	61.1 ± 1.0 (1/11)	59.7 ± 0.2 (11/11)	0.001
	D33% < 45 Gy	58.8 ± 1.6 (0/11)	56.7 ± 2.5 (0/11)	0.0006
Small bowel	D2% < 54 Gy	60.4 ± 0.7 (0/11)	58.6 ± 1.3 (0/11)	0.001
	D15% < 45 Gy	44.1 ± 9.9 (5/11)	41.0 ± 7.5 (8/11)	0.017

Figure 1. (a) NTCP for stomach each patient using Pan parameters [16]; (b) stomach D_2% for each patient; and (c) average stomach NTCP for different models. TD₅₀, m and n values are listed in Supplementary Table II: Pan [16] and Burman [24], or using range of values from Pan of TD₅₀ = 53 Gy (TD₅₀ min), m = 0.23 (m min), m = 0.39 (m max) or small bowel or combined stomach-duodenum (StoDuo) parameters.

Figure 2. NTCP for duodenum as calculated using the parameters for combined stomach and duodenum (StoDuo) and duodenum only (Duod) [16].

Pan CC, Dawson LA, McGinn CJ, Lawrence TS, Ten Haken RK. Analysis of radiation-induced gastric and duodenal bleeds using the Lyman-Kutcher-Burman model. Int J Radiat Oncol Biol Phys 2003;57(2 Suppl):S217–8.

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Burman C, Kutcher GJ, Emami B, Goitein M. Fitting of normal tissue tolerance data to an analytic-function. Int J Radiat Oncol Biol Phys 1991;21:123–35.

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