In-vivo proton range verification for reducing the risk of permanent alopecia in medulloblastoma treatment  

作　　者：Giulia Lucconi El-Hassan Bentefour Deepak Samuel Kenneth Weaver Maryam Moteabbed Hsiao-Ming Lu 

机构地区：[1]Department of Radiation Therapy,Clinique des Grangettes,Geneva,Switzerland [2]Depart of Radiation Oncology,University of Maryland,Baltimore,MD,USA [3]Saha Institute of Nuclear Physics,Kolkata,India [4]Department of Radiation Oncology,Massachusetts General Hospital,Harvard Medical School,Boston,MA,USA [5]Hefei Ion Medical Center and Ion Medical Research Institute,University of Science and Technology of China,Hefei,China

出　　处：《Radiation Medicine and Protection》2021年第3期95-102,共8页放射医学与防护（英文）

摘　　要：Objective:The purpose of this work is the clinical commissioning of a recently developed in-vivo range verification system for the head treatment of pediatric medulloblastoma patients.Inaccurate beam range for such treatment could lead to either inadequate dose coverage of the target volume or excessive dose to the head skin resulting permanent alopecia.Methods:The in-vivo range verification system is designed to perform pre-treatment range verification and adjustment.An array of Si-diode detectors is to be placed on the patient immobilization mask in the exit direction of a whole-brain field;signal is analyzed,and the extracted water equivalent path length(WEPL)is compared to the expected one,revealing if a range correction is needed.The method was tested in solid water and anthropomorphic head phantom,with validation based on independent WEPL measurements.The measured WEPL were compared to those computed by the treatment planning system(TPS).Results:The accuracy for the WEPL measurements by the diode system in both solid water and anthropomorphic head phantom were on average within a millimeter from more accurate measurement by the dose-extinction technique,with the error range for the two phantoms as(0–1 mm)and(0–1.3 mm),respectively.When compared to the WEPL calculated by the treatment planning system,the measured values were on average within 1%(range 0–3%)of the beam range.The accuracy of dose measurements by the diodes in the fall-off part of the depth dose profile was validated against the reference Markus chamber.No need for further correction(due to different beam parameters and detector dose ageing effects)was found.Conclusions:The range verification workflow was successfully tested in the anthropomorphic head phantom.The performance of the in-vivo range verification system and related workflow meet the clinical requirements in terms of the needed WEPL accuracy for pretreatment range verification.

关 键 词：Proton therapy In-vivo range verification MEDULLOBLASTOMA 

分 类 号：R739.41[医药卫生—肿瘤]