瞬发伽马活化成像的数学模型建立与模拟重建  

Mathematical model establishment, simulation and reconstruction of PGAI

作　　者：马玉华 李航[1] 杨鑫[1] 李润东[1] 黄洪文[1] Ma Yuhua;Li Hang;Yang Xin;Li Rundong;Huang Hongwen(Institute of Nuclear Physics and Chemistry CAEP,Mianyang 621900,China)

机构地区：[1]中国工程物理研究院核物理与化学研究所,四川绵阳621900

出　　处：《强激光与粒子束》2022年第5期24-29,共6页High Power Laser and Particle Beams

基　　金：国家自然科学基金联合基金重点项目(U20B2011);国家自然科学基金项目(51978218);国家自然科学基金项目(12075217);四川省科技计划项目(2019ZZDZX0010)。

摘　　要：瞬发伽马活化成像中,样品内部的中子自屏蔽和伽马自吸收效应会使测量结果产生不均匀分布。针对成像单元响应不一致的问题,研究了样品内部中子场不均匀分布和伽马自吸收效应的影响,并进行了理论推导,建立了用于修正成像单元响应和图像重建的数学模型,利用数学模型对Fe,H元素瞬发伽马活化成像的蒙特卡罗模拟进行了元素图像重建。结果显示,样品内中子场和γ自吸收对成像的影响得到明显改善,Fe和H元素的含量分布使用此模型可以被精确重建,验证了数学模型的有效性。In the prompt gamma activation imaging, the neutron self-shielding and gamma self-absorption effect inside the sample will cause uneven distribution of the measurement results. To solve the problem of the biased distribution in the prompt gamma activation imaging, the influence of the neutron field inside the sample and the selfabsorption effect of gamma were studied, and the transport process of neutrons and gamma rays was theoretically deduced. A mathematical model for correcting the biased distribution and image reconstruction was established. The Monte Carlo method was used to simulate the prompt gamma activation imaging of Fe and H elements, and the mathematical model was used to reconstruct the element images. The results show that the influence of neutron selfshielding and γ self-absorption effect in prompt gamma activation imaging has been significantly corrected, and the content distribution of Fe and H elements can be accurately reconstructed using this mathematical model, which verify the validity of the mathematical model.

关 键 词：瞬发伽马活化成像 非线性方程组 元素含量分布 蒙特卡罗模拟 PGAI重建 

分 类 号：TL99[核科学技术—核技术及应用]