Detection of interfraction displacement and volume variance during radiotherapy of primary thoracic esophageal cancer based on repeated four-dimensional CT scans

Table 3 Magnitude (cm) of interfraction GTV centroid motion for the twentieth fraction 4DCT scan

Group	LR			AP			SI			F	P	3D vector
Group	Range	Mean	SD	Range	Mean	SD	Range	Mean	SD	F	P	Range	Mean	SD
Upper	0.04-0.14	0.08	0.04	0.01-0.39	0.13	0.13	0.09-1.30	0.40	0.39	4.405	0.023	0.12-1.30	0.46	0.38
Mid-	0.02-0.34	0.14	0.10	0.01-0.41	0.16	0.14	0.01-0.55	0.37	0.20	3.614	0.041	0.02-0.58	0.42	0.17
Distal	0.01-0.54	0.16	0.10	0.01-0.54	0.31	0.16	0.45-1.66	0.86	0.39	17.919	0.000	0.54-1.67	0.96	0.36
F	3.132			3.565			10.055					9.318
P	0.062			0.044			0.001					0.001

Abbreviation: GTV gross tumor volume, 4DCT four-dimensional computed tomography, LR right–left, AP anterior–posterior, SI superior–inferior, 3D three-dimensional, SD standard deviation. “F”, the ratio of mean square about “between groups” and “within groups” used by one-way ANOVA; “P” , the significance based on two-tailed p values. Values of P < 0.05 were considered significant.

ISSN: 1748-717X