Analysis of Setup Errors in Radiotherapy Between Three-Dimensional Treatment Couch and Six-Dimensional Treatment Couch Registration by Cone Beam CT Image
Objective To analyze the setup error of radiotherapy by using the registration accuracy of cone beam CT image-guided three-dimensional and six-dimensional radiotherapy couch,and to provide reference for the management of radiotherapy process using three-dimensional radiotherapy couch in clinical practice.Methods The cone beam CT images of 50 patients with nasopharyngeal carcinoma,49 patients with esophageal cancer,and 25 patients with rectal cancer before radiotherapy were selected as the research objects.The same region of interest was set using offline registration.Rigid registration was performed separately in the linear direction of the three-dimensional radiotherapy couch and the linear and rotational directions of the six-dimensional radiotherapy couch.The resulting setup errors after registration were analyzed.Results There was a significant difference in both the vertical(Vrt)and lateral(Lat)directions(P＜0.05)in patients with nasopharyngeal carcinoma using rank sum test while rectal cancer using independent sample test for homogeneity of variance,but there was no significant difference in longitudinal(Lng)direction(P＞0.05).Rank-sum test was conducted on patients with esophageal cancer.There was a statistically significant difference(P＜0.05)in the Vrt direction,but no significant difference(P＞0.05)was found in the Lng and Lat directions.There was no significant difference(P＞0.05)in the Lng direction across all three sites.For patients with nasopharyngeal cancer,rectal cancer,and esophageal cancer,when the tolerance values in the linear direction were 3,5,and 5 mm,respectively,the quantities of tolerance ranges of 2,4,and 4 mm accounted for a significant proportion.In the translation direction,the setup errors for both registration methods were basically within the clinically set range.With six-dimensional registration,it was observed that there were larger setup errors in the head-to-foot direction for patients with nasopharyngeal cancer compared to the three rotational directions for patients with esophageal cancer and rectal cancer.Conclusion The amount of setup error information provided during registration with a three-dimensional radiotherapy couch is lower compared to a six-dimensional radiotherapy couch.When using a three-dimensional radiotherapy couch for positioning,it is necessary to strengthen the management of the entire radiotherapy process and rotational direction positioning techniques in order to improve the efficiency of radiotherapy positioning and the therapeutic gain ratio.
国家科技期刊平台
NSTL
万方数据
