Comprehensive Treatment Uncertainty Analysis and PTV Margin Estimation for Fiducial Tracking in Robotic Liver Stereotactic Body Radiation Therapy  

作　　者：Zhi-wen LIANG Meng-lan ZHAI Biao TU Xin NIE Xiao-hui ZHU Jun-ping CHENG Guo-quan LI Dan-dan YU Tao ZHANG Sheng ZHANG 

机构地区：[1]Cancer Center,Union Hospital,Tongji Medical College,Huazhong University of Science and Technology,Wuhan 430022,China

出　　处：《Current Medical Science》2023年第3期572-578,共7页当代医学科学（英文）

基　　金：This project was supported by the National Key R&D Program of China(No.2016YFC105300).

摘　　要：Objective This study aims to quantify the uncertainties of CyberKnife Synchrony fiducial tracking for liver stereotactic body radiation therapy(SBRT)cases,and evaluate the required planning target volume(PTV)margins.Methods A total of 11 liver tumor patients with a total of 57 fractions,who underwent SBRT with synchronous fiducial tracking,were enrolled for the present study.The correlation/prediction model error,geometric error,and beam targeting error were quantified to determine the patient-level and fraction-level individual composite treatment uncertainties.The composite uncertainties and multiple margin recipes were compared for scenarios with and without rotation correction during treatment.Results The correlation model error-related uncertainty was 4.3±1.8,1.4±0.5 and 1.8±0.7 mm in the superior-inferior(SI),left-right,and anterior-posterior directions,respectively.These were the primary contributors among all uncertainty sources.The geometric error significantly increased for treatments without rotation correction.The fraction-level composite uncertainties had a long tail distribution.Furthermore,the generally used 5-mm isotropic margin covered all uncertainties in the left-right and anterior-posterior directions,and only 75%of uncertainties in the SI direction.In order to cover 90%of uncertainties in the SI direction,an 8-mm margin would be needed.For scenarios without rotation correction,additional safety margins should be added,especially in the superior-inferior and anterior-posterior directions.Conclusion The present study revealed that the correlation model error contributes to most of the uncertainties in the results.Most patients/fractions can be covered by a 5-mm margin.Patients with large treatment uncertainties might need a patient-specific margin.

关 键 词：CYBERKNIFE fiducial tracking liver cancer stereotactic body radiation therapy margin expansion 

分 类 号：R730.55[医药卫生—肿瘤]