Comparation of set-up errors between two different body positions in precision radiotherapy for esophageal cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To compare the effect of set-up errors to two different body positions that are putting arms on the side of the body (A group) or placing arms folded across the elbow on forehead (B group) in esophageal cancer' fraction radiotherapy.Methods By using case-control study,all supine patients were divided into the A group and the B group.After patients were fixed by thermoplastic membrane,they were located by spiral CT and treated by using IGRT.During treatmwnt,there were three cone-beam CT scans in the first week and then at least one scan weekly.We obtained the linear set-up errors data by using bone registration with manual proofreading in 3 directions that were left and right (x),head and feet (y),abdomen and back (z) by using CBCT.Means were compared by using independent sample t-test,and ratios were compared by chi-square test.Results Every group had 11 cases that the A group had 92 people times and the B group had 87 people times.Absolute set-up errors of two different positions:only x-axis,the mean of the A group was (2.46 ± 1.79) mm.But the mean of the B group was (1.91 ± 1.71)mm,which was significantly less than the A group (P =0.036).Relative set-up errors of two groups:only y-axis,the mean of the B group was (1.91 ± 4.12) mm.The A group was (0.09 ± 3.90) mm,which was significantly less than the B group (P =0.003).There was no significant difference of three-dimensional set-up errors (P=0.751).And there was no significant difference in absolute weekly set-up errors or weekly three-dimensional set-up errors in radiotherapy (P ＞ 0.05).Conclusions The each of two body positions in esophageal cancer' fraction radiotherapy has advantage and disadvantage for set-up errors,but they were in control and didn't affect the radiotherapy planning.We can choose appropriate treatment position according to clinical practice.