高场强MR加速器的图像畸变及其影响因素分析  

Characterization of imaging distortion of high-field magnetic resonance imaging-guided linear accelerator(MR-Linac)and its influencing factors

作　　者：王彬[1] 刘红冬 刘镖水 李永宝 丁寿亮 黄晓延[1] Wang Bin;Liu Hongdong;Liu Biaoshui;Li Yongbao;Ding Shouliang;Huang Xiaoyan(State Key Laboratory of Oncology in South China,Collaborative Innovation Center for Cancer Medicine,Department of Radiation Oncology,Sun Yat-sen University Cancer Center,Guangzhou 510060,China)

机构地区：[1]中山大学肿瘤防治中心放疗科华南肿瘤学国家重点实验室肿瘤医学协同创新中心,广州510060

出　　处：《中华放射肿瘤学杂志》2021年第2期146-150,共5页Chinese Journal of Radiation Oncology

摘　　要：目的分析1.5T高场强MR加速器(MR-Linac)的图像畸变,以及MR-Linac和外设对MR图像畸变影响。方法采用特制的MR几何畸变测试模体和分析软件,建立在以磁体中心为球心的球形体积直径(DSV)内MR图像畸变的基准。分析加速器束流系统、机械系统和外设设备工作时对图像畸变的影响,并通过长期追踪测试来观察MR-Linac图像畸变的稳定性。结果高场强MR-Linac的图像畸变随着测试点距离磁体中心的距离增大图像畸变也相应增大DSV 400mm范围内绝大部分测试点在三维方向的图像畸变<1mm,400~500mm范围内部分区域的图像畸变>2mm,最大畸变>7mm。MR-Linac图像畸变在装机后7个月内保持稳定,加速器以及外设工作时仅对DSV 400~500mm范围内MR图像几何畸变的最大值有轻微影响。结论高场强MR-Linac的临床使用中应谨慎治疗肿瘤位置距离等中心>20 cm的病例。MR-Linac在装机后7个月内图像畸变保持稳定,加速器和外设工作时对图像畸变的影响有限,临床上可以忽略。Objective To characterize the imaging distortion of the 1.5T magnetic resonance imaging-guided linear accelerator(MR-Linac)and to analyze the influence of MR-Linac and peripheral devices on the geometric distortion.Methods Specialized MRI imaging distortion phantom and analysis software were applied.The baseline of imaging distortion within diameter spherical volume(DSV)around the center of the magnet was established.The influence of the beam generation system,mechanical system and peripheral devices on the imaging distortion was analyzed.The long-term stability of imaging distortion was tested on the MR-Linac.Results Imaging distortion of the MR-Linac was increased with the increasing distance to the center of the magnet.Within DSV 400mm,few test points surpassed 1mm imaging distortion in 3D directions.However,imaging distortion surpassed 2mm in part of region within DSV 400-500mm,with the largest distortion over 7mm.Imaging distortion of the MR-Linac remained unchanged within 7 months after installation.And the influence of the MR-Linac and peripheral devices on the imaging distortion was only observed in the overall largest distortion within DSV 400-500mm.Conclusions Cautions should be taken during the application of high-field MR-Linac in patients whose tumor location is over 20 cm from the ISO center.Imaging distortion of the MR-Linac remains stable within 7 months after installation.The influence of the MR-Linac and peripheral devices on the imaging distortion is trivial,which can be neglected in clinical practice.

关 键 词：磁共振加速器 图像畸变 影响因素 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术] TL50[自动化与计算机技术—计算机科学与技术]