Preliminary study on the distributions of dose differences and their correlations with tumor types in independent verification
Objective To explore the distributions of dose differences and their correlations with tumor types in independent three-dimensional dose verification for intensity-modulated radiotherapy(IMRT)plan,and to establish prediction models.Methods The fixed field IMRT plans of 180 patients with head and neck,chest,and abdominal tumors were collected.Independent sample t-test was used to analyze the consistency between the initial dose calculated in treatment planning system and the verified dose for evaluating the feasibility of independent validation.The distributions of planning target volume(PTV)dose differences among different tumor types were analyzed.The correlations of PTV dose differences with conformity index(CI)and homogeneity index were analyzed using correlation analysis and multiple linear regression method.Results The PTV dose differences for head and neck,chest,and abdominal tumors were within±1.2%,and the average 3%/3 mm gamma passing rate between the initial dose and the verified dose was higher than 99.5%,indicating good consistency in dose distribution between independent validation and treatment planning system.The distributions of PTV dose differences were different in head and neck,chest,and abdominal plans,and were significantly correlated with CI which could be used to preliminarily determine the PTV dose differences in independent validation.The multiple regression equation based on CI and homogeneity index could be used to estimate the dose verification differences of IMRT plan.Conclusion Independent verification can quickly achieve pre-treatment validation for radiotherapy plans,improving the efficiency of quality control of radiotherapy plans.The estimation based on dose differences provides guidance for optimizing radiotherapy plans.
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