Dosimetric exploration of uneven 5-field for intensity-modulated radiotherapy of esophageal cancer

XIAO Yao; ZHOU Deli; SU Kunpu; LI Linshan; SI Mengyuan; ZHOU Peng; LUO Jia; LIU Yanhai; LI Mengxia; CHEN Chuan

doi:10.13276/j.issn.2097-1656.2025.07.011

Abstract：Objective To explore the effects of different 5-field layout modes of intensity-modulated radiotherapy on the target area of mid-thoracic esophageal cancer and the dose of organs at risk.Methods Seven patients with esophageal cancer were selected from the Department of Oncology,Army Characteristic Medical Center,Army Medical University as the study objects,and four sets of static intensity-modulated plans were designed for each patient,respectively:PA:210°,240°,0°,120°,150°;PB:210°,240°,180°,120°,150°;PC:210°,300°,180°,60°,150°;PD:210°,300°,0°,60°,150°.The dose-volume parameters of the target areas and organs at risk were statistically compared among the four plans.Results The target dose of the four plans could reach 95％coverage requirements,and there was no statistical significance in D5％,D95％and Dmean.The V5 of PD double lungs was the lowest,which decreased by about 0.9％relative to the highest group.The V10 of PA double lungs decreased by about 1.9％relative to PC,and PA and PB were statistically significant(P＜0.05).The V20 of PD double lungs was the lowest,in which PD was equivalent to 0.9％decrease in PA.Dmean in PD double lungs was the lowest,which decreased by 15 cGy relative to the highest PA group.There was no significant difference in V30 and V40 between the four groups.The cardiac Dmean of PA and PC was significantly different(P＜0.05),and PB decreased by 36 cGy relative to PA.The spinal cord Dmax was as follows:PB＜PC＜PD＜PA.PB decreased by 122 cGy relative to PA in spinal cord dose-volume.Comparison of the monitor unit(MU)of the three plans showed that PB had the highest MU(469.28±79.71)and PD had the lowest(430.67±62.63),and there was no statistical significance in the comparison among the four groups.The MU of the PB plan in the group with the highest number of jumps increased by 10％compared to that in the PB plan in the group with the lowest number of jumps.Conclusion The target areas of the four groups can meet the requirements,and there is no statistical significance in the dose-volume of organs at risk,which indicates that four field angles designed in this paper can be selected when the intensity-modulated field distribution of conventional static 5-field for esophageal cancer is used.