ABSTRACT
Objective To analyze the cumulative doses after two planned radiotherapy treatments for non-small cell lung cancer with direct superposition,rigid superposition and deformation superposition.Methods Twenty-four non-small cell lung cancer patients undergoing radical radiotherapy at some hospital were selected,who went through simulation positioning and radiotherapy treatment with modified plan after receiving 20 radiotherapy sessions.The cumulative dose after two planned radiotherapy treatments was calculated and compared with three methods including direct superposition,rigid superposition of Monaco treatment planning system and deformation superposition of MIM software.Results Direct superposition had the target dose the highest among those calculated by the three methods,followed by rigid superposition and deformation superposition in turn,and both rigid superposition and deformation superposition had significant differences with direct superposition(all P＜0.05).Among the three methods direct superposition had the V5,V10 and V15 of lung and Dmean of heart and esophagus the lowest,the V20 of lung similar to that by deformation superposition while lower than that by rigid superposition and the remained indexes the highest;of the cumulative doses calculated by rigid superposition only the V5 of lung and Dmean of heart were lower than those by deformation superposition.Pairwise comparisons between the three methods showed only the differences between the Dmax of esophagus were statistically significant(all P＜0.05).Conclusion The three superposition methods have differences when used to calculate the dose-volume parameters of the target areas and organs at risk,and different superposition methods have to be taken into considerations during clinical operations to avoid over-or under-assessment of the doses to tumor and normal tissue.[Chinese Medical Equipment Journal,2023,44(10):49-54]