Dose evaluation of adaptive radiotherapy using high-field MR-Linac systems for head and neck cancers / 中华放射医学与防护杂志

ABSTRACT

Objective:To investigate the feasibilityof the adaptive radiotherapy using high-field MR-Linac systems for head neck cancers and perform the evaluation of target coverage and dose criteria.Methods:This study investigated 128 treatment plans of six patients who were treated on 1.5T MR-Linacsystems in Sun Yat-sen University Cancer Center in 2019, compared the differences in target coverage and dose criteria between the dose accumulation in the adaptive radiotherapy using MR-Linac systems and the reference plans, and evaluated the target coverage and dose criteria of each fraction of adaptive plan based on daily MRI anatomy.Results:There was no significant change in the target coverage and dose criteria for each treatment fraction(<1%). However, the change of lens dose was significant (maximum 98%). In addition, the result showed that there was no significant difference in target coverage and dose criteria between the dose accumulation in adaptive radiotherapy using MR-Linac systems and reference plans.In contrast, the average dose to lens was increased by 31.7%.Conclusions:It is feasible to perform adaptive radiotherapy using 1.5T MR-Linacsystems for head neck cancers according tothe evaluation of target coverage and dose criteria. Additionally, since the actual dose tolens was quite different from the reference plan, the lens exposure should be considered in clinical practice.