Speaker
摘要
高能量分辨率、高空间分辨率和高灵敏度的γ射线探测器是提升核医学单光子成像性能的关键。传统 NaI(Tl) 闪烁体探测器在能量分辨率方面存在局限，而 CdZnTe 等半导体探测器虽具有较优性能，但其成本和材料制备仍限制了进一步推广。钙钛矿 CsPbBr3 半导体兼具高阻止能力、室温工作能力和潜在低成本优势，为发展新型核医学γ相机提供了新的材料基础。本工作围绕像素化 CsPbBr3 半导体探测器，构建了面向 99mTc 单光子γ成像的原型探测系统，并通过表面电荷收集优化、像素化电极设计、多通道读出和深度校正，实现了优异的能谱和成像性能。实验结果表明，该探测器在 99mTc 141 keV γ射线下实现 2.5% 的整体能量分辨率，在 137Cs 662 keV 下实现 1.0% 的整体能量分辨率；点源和线源成像灵敏度达到 0.13%–0.21% cps/Bq，Derenzo phantom假体成像空间分辨率约为 3.2–3.8 mm，证明了 CsPbBr3 钙钛矿探测器用于核医学单光子γ成像的可行性。
进一步地，针对像素化钙钛矿探测器中电荷输运、权重势分布、电荷共享和深度依赖脉冲形状等复杂物理过程，本工作建立了动态电荷感应与信号生成数值模拟框架。该框架集成 Geant4 能量沉积模拟、有限元电场与权重势计算、电子/空穴输运追踪、Shockley–Ramo 感应电荷计算以及 CSA 脉冲和 CR-RC4 成形信号模拟，能够从物理过程出发重建探测器的实时波形和能谱响应。模拟结果与实验脉冲和能谱具有良好一致性，并可用于分析电荷共享事件、作用深度效应和位置依赖的电荷收集损失。基于三维电荷损失校正，模拟能谱的能量分辨率由约 5.5% 改善至 1.5%，显示了该框架在探测器结构优化、信号校正和脉冲处理算法开发中的应用潜力。综上，本研究从器件性能验证和物理机理建模两个层面，展示了钙钛矿半导体γ射线探测器在下一代核医学单光子成像系统中的发展前景。
Abstract
High energy resolution, spatial resolution, and detection sensitivity are essential for improving single-photon nuclear medicine imaging. Conventional NaI(Tl)-based scintillation cameras are widely used but limited by their moderate energy resolution, while CdZnTe semiconductor detectors provide improved performance but still face challenges related to cost and material growth. CsPbBr₃ perovskite semiconductors, featuring strong γ-ray stopping power, room-temperature operation, and potential cost-effectiveness, offer a promising route toward next-generation γ-ray cameras. In this work, we developed a pixelated CsPbBr₃ semiconductor detector system for 99mTc single-photon γ-ray imaging. Through surface charge-collection optimization, pixelated electrode design, multichannel readout, and depth correction, the detector achieved excellent spectroscopic and imaging performance. The overall energy resolution reached 2.5% at 99mTc 141 keV and 1.0% at 137Cs 662 keV. Single-photon imaging using point and line 99mTc sources demonstrated sensitivities of 0.13%–0.21% cps/Bq, and Derenzo phantom imaging resolved column sources with a spatial resolution of approximately 3.2–3.8 mm. These results demonstrate the feasibility of CsPbBr₃ perovskite detectors for nuclear medicine γ-ray imaging.
To further understand and optimize the detector response, we established a numerical framework for dynamic charge induction and signal generation in pixelated perovskite semiconductor detectors. The framework integrates Geant4-based energy deposition, finite-element electric-field and weighting-potential calculations, electron and hole transport tracking, Shockley–Ramo induced-charge modeling, and charge-sensitive amplifier and CR-RC⁴ shaping simulations. It enables physics-based reconstruction of real-time waveforms and energy spectra, and provides insight into charge sharing, depth-dependent pulse formation, and position-dependent charge collection loss. The simulated waveforms and spectra show good agreement with experimental observations. Moreover, by applying three-dimensional charge-loss correction, the simulated energy resolution was improved from approximately 5.5% to 1.5%, indicating the potential of this framework for detector design optimization, signal correction, and pulse-processing algorithm development. Overall, these studies establish a coherent pathway from experimental device demonstration to physics-based signal modeling, supporting the development of high-performance, low-cost perovskite semiconductor γ-ray cameras for future nuclear medicine applications.
| 关键词 | 钙钛矿半导体；CsPbBr3；γ射线探测器；核医学成像；单光子成像；电荷感应模拟 |
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| Keywords | perovskite semiconductor; CsPbBr₃; γ-ray detector; nuclear medicine imaging; single-photon imaging; charge-induction simulation |
