TOF-PET with high-efficiency TlCl crystals

具有高效 TlCl 晶体的 TOF-PET

• 批准号: 10660173
• 负责人: Gerard Ariño Estrada
• 金额: $ 63.9万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10660173
• 关键词: Adoption; Background Radiation; Behavior; Beryllium; Biomedical Engineering; Bismuth; California; Cardiovascular Diseases; Cells; Chlorides; Coupled; Data; Detection; Development; Diagnosis; Dimensions; Discipline of Nuclear Medicine; Dose; Elements; Evaluation; Evolution; Floods; Foundations; Generations; Geometry; Goals; Growth; Human Resources; Image; Indium; Individual; Iodine; Light; Love; Lutetium; Malignant Neoplasms; Measures; Modality; Modeling; Musculoskeletal Diseases; Optics; Pathology; Performance; Positron-Emission Tomography; Preparation; Process; Production; Property; Radiation; Radiation Monitoring; Research; Research Personnel; Resolution; Sampling; Silicon; Staging; Structure; Surface; Techniques; Testing; Thallium; Time; Universities; Width; Yttrium; cancer diagnosis; cost; detector; experience; flexibility; imaging modality; improved; man; melting; models and simulation; monitoring device; novel; nuclear imaging; photomultiplier; photonics; physical property; radiation detector; scale up; simulation; temporal measurement; theranostics; uptake

Summary Time-of-flight positron emission tomography is a very effective nuclear imaging modality for the diagnosis and staging of a range of pathologies such as cancer, cardiovascular diseases, or musculoskeletal disorders. Commercial TOF-PET scanners currently employ lutetium-(yttrium)-oxyorthosilicate (L(Y)SO) crystal detectors coupled to silicon photomultipliers (SiPMs) to achieve coincidence time resolutions (CTR) between 200-500 ps full width at half maximum (FWHM). High production costs of L(Y)SO crystals and their intrinsic radiation background are currently hindering the evolution and spread of very promising TOF-PET modalities such as long axial field-of-view (LA-FOV) scanners or studies involving very low doses such as cell tracking or imaging with theranostic agents. New scintillator materials with lower production cost, radiation background-free, and with TOF-level timing accuracy are needed. We propose to use thallium chloride (TlCl) as a scintillator material for TOF-PET. TlCl is a material with a simple cubic structure that allows for a relatively easy and flexible doping process. Preliminary data obtained with TlCl crystals doped with beryllium (Be) and indium (I) show a very fast scintillation component of ~10 ns that has a high potential for very accurate timing measurements. TlCl has a greater detection efficiency than LYSO or even bismuth germanate (BGO) for 511 keV gammas, is background radiation-free, and its estimated production cost is 1/3 of L(Y)SO based on its low melting point of 430C (compared to 2050C for L(Y)SO) and simple lattice structure. Moreover, unlike BGO, TlCl uniquely combines a very fast scintillation process with a high Cherenkov generation yield to further boost timing potential. We aim to prove the feasibility of using TlCl detectors for TOF-PET by combining expertise in crystal growth, simulation of light generation and detection, and benchtop characterization. First, will study the effects of Be and I as dopants in TlCl with the aim of further improve the scintillation properties observed in the preliminary data. We will also optimize the surface treatment of TlCl to maximize the light extraction toward the photodetector. Second, we will develop a simulation framework that allows us to guide the crystal development process and to understand the fundamental timing limits of TlCl. Third, we will characterize individual TlCl crystals with different choices of photodetectors to evaluate their timing and energy resolution accuracy. Results obtained with these crystals will be used to tune and validate the simulation model as well. Finally, we will evaluate the performance of TlCl detector blocks of 4x4 crystal elements. We will evaluate their timing resolution, depth-of-interaction estimation accuracy, and quality of flood histograms.

总结 飞行时间正电子发射断层扫描是一种非常有效的核成像方式， 对一系列病理如癌症、心血管疾病或肌肉骨骼疾病进行分期。 商业TOF-PET扫描仪目前采用氧硅酸镥（钇）（L（Y）SO）晶体检测器 耦合到硅光电倍增管（SiPM），以实现200-500 ps之间的符合时间分辨率（CTR 半高宽（FWHM） 目前，L（Y）SO晶体的高生产成本和它们固有的辐射背景阻碍了其应用。 非常有前途的TOF-PET模式的发展和推广，例如长轴向视场（LA-FOV）扫描仪 或涉及非常低剂量的研究，例如用治疗诊断剂进行细胞跟踪或成像。新型闪烁体 需要具有较低生产成本、无辐射背景和具有TOF级定时精度的材料。 我们建议使用氯化铊（TlCl）作为TOF-PET的闪烁体材料。TlCl是一种具有简单 立方结构，其允许相对容易和灵活的掺杂工艺。用TlCl获得的初步数据 掺杂铍（Be）和铟（I）的晶体显示出~10 ns的非常快的闪烁分量， 非常精确的定时测量的高潜力。TlCl具有比LYSO更高的检测效率，甚至比LYSO更高的检测效率。 锗酸铋（BGO）的511 keV的伽马，是本底辐射免费，其估计的生产成本 是L（Y）SO的1/3，基于其430 ° C的低熔点（与L（Y）SO的2050 ° C相比）和简单的晶格 结构此外，与BGO不同，TlCl独特地将非常快的闪烁过程与高切伦科夫（Cherenkov）结合在一起 发电产量，以进一步提高定时潜力。 我们的目标是通过结合晶体生长方面的专业知识， 光产生和检测的模拟以及台式表征。首先，将研究Be和 I作为TlCl中的掺杂剂，目的是进一步改善初步数据中观察到的闪烁特性。 我们还将优化TlCl的表面处理，以最大化朝向光电探测器的光提取。 其次，我们将开发一个模拟框架，使我们能够指导晶体开发过程， 了解TICI的基本时间限制。第三，我们将用不同的TlCl晶体来表征单个TlCl晶体。 光电探测器的选择，以评估其定时和能量分辨率的准确性。结果与这些 晶体也将用于调整和验证模拟模型。最后，我们将评估性能 的TlCl检测器块的4x 4晶体元件。我们将评估它们的时间分辨率， 估计精度和洪水直方图的质量。