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

Table 2 Magnitude (cm) of interfraction GTV centroid motion for the tenth 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	0.01-0.35	0.13	0.11	0.01-0.26	0.13	0.09	0.01-0.65	0.31	0.25	3.745	0.038	0.03-0.78	0.39	0.23
Mid-	0.02-0.32	0.14	0.10	0.01-0.46	0.15	0.13	0.01-0.75	0.33	0.23	3.806	0.034	0.05-0.77	0.41	0.23
Distal	0.01-0.17	0.14	0.04	0.08-0.50	0.21	0.13	0.13-0.87	0.51	0.25	13.672	0.000	0.25-0.89	0.59	0.22
F	0.168			0.892			3.681					3.251
P	0.846			0.421			0.038					0.048

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