评估磁共振成像系统电磁安全的数值计算方法

发布时间：2018-02-16 01:55

本文关键词： 磁共振成像电磁场电磁安全生物效应人体数值模型数值计算方法　出处：《高电压技术》2017年08期 　论文类型：期刊论文

【摘要】：近年来,随着磁共振成像(magnetic resonance imaging,MRI)技术的快速发展,其电磁安全性得到了越来越广泛的重视。为此,综合评述了近几年的研究成果,首先介绍了MRI系统产生的静磁场、梯度场和射频场这3种不同性质的电磁场的生物效应及其安全标准,并在此基础上着重介绍了评估MRI系统电磁安全的数值计算方法,分别就人体数值模型和数值计算方法针对准确度和计算效率详细展开了分析和评价。研究结果表明:当MRI产生的3种电磁场超过一定限值时,会引发生物效应,导致受检者的身体出现不适反应;现有人体模型分辨率高,可较准确地反映真实人体组织,但通用模型限制了高场MRI设备优势的发挥,开发个体体素模型是必然发展趋势;现有的用来评估MRI电磁安全的数值计算方法包括有限元法、矩量法和时域有限差分方法,以及准静态近似方法和混合数值计算方法等衍生计算方法,这些方法能较准确地预测人体组织内的电磁场值,但无法兼顾准确度和高计算效率,仍需进一步改善;现有的安全标准尚不完善,未来应补充开放式MRI系统、PET/MRI多模成像技术以及LINAC/MRI介入治疗系统等新型系统的安全标准。该研究结果可以为MRI设计人员提供参考,帮助补充完善现有的MRI安全标准,在保证安全性的条件下提高系统性能。
[Abstract]:In recent years, with the rapid development of magnetic resonance imaging (resonance) technology, more and more attention has been paid to its electromagnetic security. The biological effects and safety standards of three different electromagnetic fields, gradient field and radio frequency field, are introduced, and the numerical calculation method for evaluating electromagnetic safety of MRI system is introduced. The human numerical model and numerical calculation method are analyzed and evaluated in detail in terms of accuracy and computational efficiency. The results show that biological effects will be induced when the three electromagnetic fields produced by MRI exceed a certain limit. The present human model has high resolution and can accurately reflect the real human tissue, but the universal model limits the advantage of high-field MRI equipment, and the development of individual voxel model is an inevitable trend. The existing numerical methods to evaluate the electromagnetic safety of MRI include finite element method, moment method and finite-difference time-domain method, as well as quasi-static approximation method and hybrid numerical method. These methods can accurately predict the electromagnetic field values in human tissues, but they cannot balance accuracy with high computational efficiency and need to be further improved; existing safety standards are not yet perfect. In the future, the open MRI system should be supplemented with the new safety standards of PET / MRI multimode imaging technology and LINAC/MRI interventional therapy system. The results of this study can provide reference for MRI designers and help to supplement and perfect the existing MRI safety standards. The system performance is improved under the condition of ensuring security.
【作者单位】：中国科学院电工研究所;中国科学院大学;
【基金】：国家自然科学基金(1154200019)~~
【分类号】：O441

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