Scattering coded imaging system and its optimal design

Abstract [Background] With the development of high-current pulsed power devices, intense pulsed gamma radiation measurement and diagnostic techniques face new challenges as conventional methods are limited in spatial arrangement and interference resistance. [Purpose] This study aims to propose a scattering coded imaging system for accurately measuring the dose field intensity distribution of intense pulsed gamma radiation, with an optimized design of the coded aperture to enhance the imaging performance of the system. [Methods] Firstly, a thin scattering target was used to reduce gamma ray intensity, protecting the imaging detector from dose rate damage while minimizing changes to the pulsed radiation field parameters. Secondly, the ring aperture was chosen as the coded aperture for the imaging system, with its inner diameter, ring width, and thickness optimized through the application of genetic algorithms in conjunction with the MCNP code. Thirdly, to validate the optimization results, the spatial resolution of the imaging systems corresponding to the optimized ring aperture, ring aperture without optimal parameters, and pinhole aperture was quantitatively evaluated using a line-pairs source of varying widths. Additionally, the imaging quality of the three systems was compared under conditions of misalignment and non-uniform source intensity. Finally, bilateral filtering was applied to the reconstructed images to enhance contrast and achieve a more uniform distribution. [Results] The genetic algorithm optimization shows that the optimal reconstructed image correlation coefficient is achieved with an inner diameter of 2.730 cm, a ring width of 2.147 cm, and a thickness of 4.230 cm. The imaging system employing the optimized ring aperture as the coded aperture demonstrates superior spatial resolution compared to both the ring aperture without optimal parameters and the traditional pinhole aperture. Additionally, under conditions of misalignment and non-uniform source intensity, the optimized ring aperture maintains higher reconstruction quality than the other two systems. The application of bilateral filtering further enhances the contrast and uniformity of the reconstructed images, bringing the optimized ring aperture reconstruction closer to the actual source image. [Conclusions] This study proposes a novel scattering coded imaging system with an optimized design aimed at accurately measuring the intensity distribution of the dose field in intense pulsed gamma radiation fields. Through optimization, the system achieves high robustness and accuracy within a compact space, effectively addressing radiation imaging needs in extreme radiation environments. This system provides a new way to realize radiation imaging in extreme radiation environments.

摘要
【背景】随着强流脉冲功率装置的发展，强脉冲γ辐射测量与诊断技术面临全新挑战：传统方法在空间排布与抗干扰能力上存在显著局限。
【研究目的】本研究旨在提出一种散射编码成像系统(scattering coded imaging system)，以精准测量强脉冲γ辐射的剂量场强度分布，并通过优化编码孔径(coded aperture)设计提升系统成像性能。
【研究方法】首先，采用薄散射靶降低γ射线强度，既保护成像探测器免受剂量率损伤，又尽可能减小对脉冲辐射场参数的扰动；其次，选取环形孔径作为成像系统的编码孔径，结合MCNP程序与遗传算法对其内径、环宽及厚度进行优化；第三，为验证优化结果，采用不同宽度的线对源(line-pairs source)对优化参数环形孔径、未优化参数环形孔径以及传统针孔孔径对应的成像系统的空间分辨率进行定量评估；此外，在源未对准与源强度非均匀的条件下，对比三种系统的成像质量；最后，对重建图像应用双边滤波(bilateral filtering)以提升对比度并实现更均匀的分布。
【研究结果】遗传算法优化结果表明，当内径为2.730 cm、环宽为2.147 cm、厚度为4.230 cm时，可获得最优的重建图像相关系数。采用优化后环形孔径作为编码孔径的成像系统，其空间分辨率优于未优化参数的环形孔径与传统针孔孔径；此外，在源未对准与源强度非均匀的条件下，优化后的环形孔径相比另外两种系统仍能保持更高的重建质量；双边滤波的应用进一步提升了重建图像的对比度与均匀性，使优化环形孔径的重建结果更接近真实源图像。
【结论】本研究提出了一种新型散射编码成像系统，并针对其开展优化设计，以精准测量强脉冲γ辐射剂量场的强度分布。通过优化，该系统在紧凑空间内实现了高鲁棒性与高精度，有效解决了极端辐射环境下的辐射成像需求，为极端辐射环境下的辐射成像提供了全新实现路径。