Implementation of volumetric modulated arc therapy for rectal cancer: Pitfalls and challenges

Figures & data

Figure 1. Average dose-volume histograms of small bowel, large bowel and bowel bag: VMAT prone with bellyboard versus VMAT supine. Doses are in Gy, volumes in cm³.

Table I. Dosimetrical comparison VMAT prone with bellyboard versus VMAT supine (median, IQR).

Volume	Dose parameter	VMAT prone with bellyboard	VMAT supine	p-Value
PTV	Volume	1347.2 (1170.7–1505.0)	1258.1 (1117.7–1406.5)	0.062
	D2	46.6 (46.4–46.7)	46.3 (46.2–46.6)	0.110
	D98	42.0 (42.0–42.6)	42.2 (42.0–42.8)	0.374
	Dmean	45.0 (45.0–45.3)	45.0 (45.0–45.2)	0.176
	CI	0.96 (0.95–0.98)	0.96 (0.95–0.97)	0.237
	HI	9.31 (7.58–10.44)	9.51 (8.42–10.56)	0.213
Small bowel	Volume	154.8 (51.8–262.2)	348.0 (278.4–536.4)	0.010
	Dmean	16.4 (2.1–21.1)	16.6 (6.7–21.0)	0.534
	V15	64.4 (0.0–121.9)	194.8 (48.5–279.0)	0.008
	V45	0.2 (0.0–14.0)	1.7 (0.0–19.8)	0.779
Large bowel	Volume	66.3 (45.2–134.6)	117.7 (78.2–308.9)	0.013
	Dmean	19.2 (16.2–26.8)	22.0 (18.5–29.4)	0.328
	V15	38.5 (16.2–89.0)	71.3 (59.1–256.1)	0.006
	V45	1.0 (0.4–6.0)	2.6 (0.5–5.1)	1.000
Bowel bag	Volume	1029.0 (716.7–1235.0)	1343.7 (1067.5–1792.8)	0.008
	Dmean	16.2 (14.6–19.1)	16.0 (14.8–19.0)	0.929
	V15	433.4 (342.0–563.3)	762.2 (483.7–1038.7)	0.003
	V45	28.1 (22.8–52.3)	37.3 (16.6–44.9)	0.594
Bladder	Volume	92.7 (57.9–159.4)	111.0 (82.0–196.8)	0.003
	D2	44.4 (42.6–45.8)	45.3 (44.2–45.6)	0.155
	Dmean	30.5 (28.2–33.0)	29.4 (25.2–33.0)	0.790
	V40	22.0 (6.9–35.4)	26.9 (4.9–40.4)	0.374

Doses are in Gy, volumes in cm³. Bold values depict statistical significance.