Normal tissue sparing with respiratory adapted volumetric modulated arc therapy for distal oesophageal and gastro-oesophageal tumours

Figures & data

Table I. Objectives and constraints for oesophageal VMAT planning.

Objectives
Minimise RMS* dose around PTV	54 Gy	Weight 100
Minimise PTV volume irradiated to	57 Gy	Weight 20
Maximise PTV volume irradiated to	51 Gy	Weight 20
Constraints
Spinal cord	Maximum dose	< 45 Gy
Lungs	V20Gy	< 20%
Liver	V30Gy	< 30%
Heart	Mean dose	< 25 Gy
PTV	Maximum dose	< 58 Gy

*RMS (root mean square).

Figure 1. PTV volume as compared to standard PTV (SP).

Table II. Summary of target coverage.

	Standard plan mean (SD)	4D plan mean (SD)	BH plan (SD)
PTV 95% coverage	95.0 (± 6.3)	91.0 (± 5.3)	91.0 (± 6.3)
PTV max dose (Gy)	58.0 (± 1.2)	58.0 (± 1.2)	58.3 (± 1.4)
PTV min dose (Gy)	47.0 (± 1.5)	43.8 (± 3.3)	44.5 (± 6.1)
PTV mean (Gy)	54.0 (± 0.2)	54.0 (± 0.004)	54.0 (± 0.01)
D2 (Gy)	57.4 (± 1.0)	57.6 (± 1.2)	57.6 (± 1.1)
D5 (Gy)	57.0 (± 0.9)	57.1 (± 1.0)	55.5 (± 5.5)
D50 (Gy)	54.0 (± 0.3)	54.1 (± 0.3)	54.1 (± 0.3)
D98 (Gy)	50.6 (± 1.2)	49.3 (± 1.6)	49.2 (± 1.9)
CN	0.7 (± 0.1)	0.8 (± 0.1)	0.8 (± 0.1)
HI	0.1 (± 0.03)	0.2 (± 0.04)	0.2 (± 0.05)

CN, conformity number; HI, homogeneity index number.

Figure 2. DVH Analysis (a) mean cardiac dose and (b) Lung V20.