全数字PET关键材料硅酸钇镥闪烁晶体研究进展

郑睿; 陈警斌; 刘雨龙; 肖鹏; 谢庆国

doi:10.15953/j.ctta.2024.014

全数字PET关键材料硅酸钇镥闪烁晶体研究进展

郑睿^1,,
陈警斌¹,
刘雨龙¹,
肖鹏^{1, 2, 3},
谢庆国^{1, 2, 3, ,}

1.
中国科学技术大学电子工程与信息科学系，合肥230026
2.
华中科技大学生物医学工程系，武汉430074
3.
武汉光电国家研究中心，武汉430074

基金项目: 国家自然科学基金国家重大科研仪器研制（质子束在生物组织内的能量输运观测装置（61927801））；国家自然科学基金原创探索计划项目延续（多计数阈值全数字硅光电倍增器（62250002））；中国科学技术大学启动基金（全立体角PET-EPR多模智能成像研究）。

详细信息

作者简介:
郑睿: 男，中国科学技术大学电子工程与信息科学系特任副研究员，主要从事闪烁晶体生长研究，E-mail：zhengrui@ustc.edu.cn

通讯作者:
谢庆国: 男，华中科技大学生物医学工程系、中国科学技术大学电子工程与信息科学系教授，主要从事正电子发射断层成像（PET）方法研究与仪器研制，E-mail：qgxie@hust.edu.cn。

中图分类号: TP 391.41；R 812
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出版历程
- 收稿日期: 2023-08-29
- 修回日期: 2024-03-05
- 录用日期: 2024-03-28
- 网络出版日期: 2024-04-16
- 刊出日期: 2024-07-27

Advance in Lutetium Yttrium Silicate Scintillation Crystal for All-Digital PET

ZHENG Rui^1,,
CHEN Jingbin¹,
LIU Yulong¹,
XIAO Peng^{1, 2, 3},
XIE Qingguo^{1, 2, 3, ,}

1.
Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei 230026, China
2.
Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
3.
Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China

摘要

摘要:
硅酸钇镥（LYSO）凭借其优异的综合性能，已成为正电子发射断层成像（PET）中最为主流的闪烁晶体材料。近年来，由多电压阈值（MVT）理论发展而来的全数字PET技术，实现了闪烁脉冲的源头数字化，提高了PET成像空间分辨率、系统灵敏度等关键指标，催生了质子治疗监测、正电子寿命谱等新应用。不同于传统的时间间隔采样方法，MVT是一种基于电压-时间的纵向采样技术，在时间很快的脉冲信号采样领域具有天然优势。因此，调控LYSO晶体的闪烁发光特性，以适应MVT采样方法，从而发掘其精准数字化的最大潜能，是全数字PET应用需求下LYSO闪烁晶体的一个新的发展方向。本文综述LYSO晶体的闪烁原理、性能调控和生长技术。梳理如何调制LYSO晶体光输出、衰减时间和均一性等关键性能，以适应全数字PET的采样特性。介绍本团队面向全数字PET需求，开发的快衰减、高均一LYSO晶体的研究进展。最后，结合LYSO研究现状和全数字PET探测器的新需求，展望LYSO闪烁晶体的未来发展方向。
- PET /
- 闪烁晶体 /
- 硅酸钇镥 /
- 晶体生长
Abstract:
Lutetium yttrium silicate (LYSO) has become the most prominent scintillation crystal material in positron emission tomography (PET) because of its outstanding comprehensive performance. In recent years, the emerging All-Digital PET technology based on the Multi-Voltage Threshold (MVT) method has digitized the origin of scintillation pulses, thereby improving key metrics such as spatial resolution and system sensitivity; this advancement has also given rise to new applications like proton therapy monitoring and positron lifetime spectroscopy. Unlike traditional time interval sampling methods, MVT represents a longitudinal sampling technique based on voltage-time, offering inherent advantages in rapidly varying pulse signal sampling domains. Consequently, tailoring the scintillation luminescence properties of LYSO crystals to adapt to the MVT sampling method becomes a new development direction for LYSO scintillation crystals under the demand of digital PET applications. This paper reviews the scintillation principles, performance modulation, and growth techniques of LYSO crystals. It outlines strategies for adjusting key properties of LYSO crystals, such as light output, decay time, and uniformity to align with the sampling characteristics of All-Digital PET. Furthermore, the paper presents the research progress of fast-decaying and highly uniform digitally modified LYSO crystals developed by the research team to meet the demands of All-Digital PET. Finally, based on the current research status of LYSO and the new demand for digital PET, the future development direction of LYSO scintillation crystals is discussed.
- PET /
- scintillation crystal /
- LYSO /
- crystal growth

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图 1 LYSO：Ce晶体闪烁原理

Figure 1. Scintillation mechanism of LYSO：Ce crystal

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图 2 氧空位缺陷降低LYSO：Ce中5d-4f跃迁效率的示意图

Figure 2. Principle of oxygen vacancy defect reducing 5d-4f transition efficiency in LYSO：Ce

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图 3 Ce³⁺和 Ce⁴⁺参与的闪烁发光过程

Figure 3. Scintillation process involving Ce³⁺ and Ce⁴⁺

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图 4 LYSO基质中三价镧系离子能级位置示意图

Figure 4. Energy levels of trivalent lanthanide ions in LYSO

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图 5 MVT采样方法与闪烁脉冲的时间特性

Figure 5. The relationship between the MVT sampling method and the time characteristics of scintillation pulses

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图 6 MVT采样方法与闪烁脉冲的波形一致性

Figure 6. The relationship between the MVT sampling method and the uniformity of scintillation pulses

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图 7 提拉法晶体可控生长平台的总体结构

Figure 7. Overall structure of crystal growth platform controlled by Czochralski method

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图 8 高均一改良LYSO晶体外观和闪烁性能一致性

Figure 8. Consistency of appearance and scintillation of high homogeneous modified LYSO crystal

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图 9 快衰减LYSO晶体生长优化和荧光衰减时间性能

Figure 9. Growth optimization and decay time of the fast decay LYSO crystal

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图 10 读出电路设计

Figure 10. Readout circuit design

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图 11 符合时间分辨率测试实验设置

Figure 11. The setup of time resolution measurement

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图 12 符合时间分辨率测试结果

Figure 12. The results of time resolution

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表 1 光学惰性稀土元素三价离子Sc³⁺, Y³⁺, La³⁺, Gd³⁺ 和Lu³⁺

Table 1 Rare earth trivalent ions Sc³⁺, Y³⁺, La³⁺, Gd³⁺ and Lu³⁺ with optical inertia

元素	原子电子结构	三价离子电子结构	三价离子半径/pm
Sc	[Ar]3d¹4s²	[Ar]	88.5
Y	[Kr]4d¹5s²	[Kr]	104
La	[Xe]4f⁰5d¹6s²	[Xe]4f⁰	117
Gd	[Xe]4f⁷5d¹6s²	[Xe]4f⁷	107
Lu	[Xe]4f¹⁴5d¹6s²	[Xe]4f¹⁴	100

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