Reduced Afterglow Scintillator Films for High Speed Medical Imaging

用于高速医学成像的减少余辉闪烁体薄膜

• 批准号: 7932004
• 负责人: VIVEK V NAGARKAR
• 金额: $ 68.69万
• 依托单位: RADIATION MONITORING DEVICES, INC.
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-18 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7932004
• 关键词: Affect; Area; Arts; Ceramics; Characteristics; Charge; Chemicals; Communities; Complement; Complex; Cost Savings; Data; Deposition; Development; Devices; Diagnostic; Digital Mammography; Dimensions; Discipline of Nuclear Medicine; Dose; Due Process; Dura Mater; Elements; Equipment; Error Sources; Evaluation; Exhibits; Exposure to; Film; Fluoroscopy; Gamma Rays; Goals; Hand; Image; Kinetics; Life; Light; Medical; Medical Imaging; Modality; Morphology; Nature; Nuclear; Operative Surgical Procedures; Output; Patients; Performance; Phase; Photons; Physics; Physiologic pulse; Positron-Emission Tomography; Process; Property; Radiation; Radionuclide Imaging; Research Personnel; Residual state; Resolution; Sampling; Scanning; Security; Shadowing (Histology); Silicon; Source; Spectrum Analysis; Speed; Structure; System; Techniques; Technology; Temperature; Thick; Thoracic Radiography; Time; Variant; Vendor; X-Ray Computed Tomography; X-Ray Computed Tomography Scanners; attenuation; base; commercial application; commercialization; cone-beam computed tomography; cooperative study; cost; data acquisition; density; detector; economic impact; evaporation; imaging modality; improved; interest; irradiation; melting; operation; programs; public health relevance; sensor; single photon emission computed tomography; tomography

DESCRIPTION (provided by applicant): While many exotic new scintillation materials are now being developed, few even come close to CsI:Tl in performance and versatility. Widely available commercially at low cost, CsI:Tl not only has superb scintillation efficiency, but also can readily be fabricated as large-area microcolumnar films for high-resolution imaging, making it the material of choice for a wide range of applications. Unfortunately, CsI:Tl exhibits both a strong afterglow component in its scintillation decay and severe hysteresis after prolonged irradiation, limiting achiev- able energy resolution and imaging quality and speed. These shortcomings effectively preclude its use in applica- tions such as radionuclide imaging and medical CT, where its low cost could otherwise have immense economic impact. An improved form of CsI:Tl scintillator can reduce the cost of critical life-saving medical equipment such as X-ray CT scanners, fluoroscopy systems and other devices that rely on rapid data acquisition. In systematic studies of the cooperative effects of codopants in CsI:Tl, we have identified additives that can suppress its afterglow by as much as two orders of magnitude while maintaining its extraordinary scintillation properties. We also find that similar treatment can diminish hysteresis by more than a factor of ten, represent- ing a major breakthrough that has eluded researchers for decades. Moreover, we have clearly established that, through a co-evaporation technique, we can deposit thick microcolumnar films of this modified material, which provide very high spatial resolution appropriate for such new and exciting applications as "nanoSPECT" and high-speed cone-beam CT using flat panel detectors. With these exceptional properties, codoped CsI:Tl is now poised for exploitation in many rapid imaging modalities from which CsI:Tl had been previously excluded. But while we have achieved all these desirable effects in melt-grown crystals, we have not yet combined them at satisfactory levels at a single film composition; this is the specific goal of Phase I. Having already established the feasibility of the multicomponent deposition process itself, we will reach this goal through careful and system- atic variation of deposition parameters such as source and substrate temperatures, source-substrate distances, and chemical make-up of the sources themselves. Phase I will produce material with scintillation properties at least as good as in melt-grown single crystals, thereby becoming immediately useful for commercial evaluation. Phase II has far more comprehensive goals than Phase I. Here we will seek to optimize the material in terms of both chemical composition and physical morphology. In addition, guided by the results of Phase I and input from substantial new theoretical support, we will seek to understand both the mechanisms responsible for the observed effects and the kinetic factors that govern the deposition process itself. Cognizant of their ultimate applications, we will grow microcolumnar films of various dimensions ranging from 5 x 5 cm2 to 50 x 50 cm2, and demonstrate their utility by evaluating film performance in CBCT and SPECT modes of operation. Finally, we will promote commercialization through cooperative programs with potential users of this technology. PUBLIC HEALTH RELEVANCE: The widely available, low cost CsI:Tl not only has superb scintillation efficiency, but also can readily be fabricated as large-area microcolumnar films for high-resolution imaging, making it the material of choice for a wide range of applications. Unfortunately, CsI:Tl exhibits both a strong afterglow component in its scintillation decay and severe hysteresis after prolonged irradiation, limiting achievable energy resolution and imaging quality and speed. These shortcomings effectively preclude its use in applications such as radionuclide imaging and medical CT, where its low cost could otherwise have immense economic impact. An improved form of CsI:Tl scintillator, such as the one proposed here, can reduce the cost of critical life-saving medical equipment such as X-ray CT scanners, fluoroscopy systems and other devices that rely on rapid data acquisition.

描述(申请人提供)：虽然目前正在开发许多奇异的新闪烁材料，但很少有材料在性能和通用性上接近CSI：TL。CsI：Tl不仅具有极高的闪烁效率，而且可以很容易地制作成用于高分辨率成像的大面积微柱状薄膜，使其成为广泛应用的材料。不幸的是，CsI：Tl在其闪烁衰减过程中表现出强烈的余辉成分，在长时间照射后表现出严重的滞后，限制了可实现的能量分辨率和成像质量和速度。这些缺点有效地阻止了它在放射性核素成像和医用CT等应用中的使用，否则它的低成本可能会产生巨大的经济影响。一种改进的CSI：TL闪烁体可以降低关键的救命医疗设备的成本，如X射线CT扫描仪、荧光透视系统和其他依赖快速数据采集的设备。在对CsI：Tl中共掺杂协同效应的系统研究中，我们已经确定了可以在保持其非凡闪烁特性的同时抑制其余辉高达两个数量级的添加剂。我们还发现，类似的处理可以将磁滞减少十倍以上，这代表着几十年来研究人员一直未能实现的重大突破。此外，我们清楚地证明，通过共蒸发技术，我们可以沉积这种改性材料的厚微柱状薄膜，这种薄膜提供非常高的空间分辨率，适合于使用平板探测器的新的和令人兴奋的应用，如“纳米SPECT”和高速锥束CT。由于具有这些特殊的性质，共掺杂的CsI：Tl现在有望在许多以前不包括CsI：Tl的快速成像模式中得到开发。但是，虽然我们已经在熔融生长晶体中实现了所有这些理想的效果，但我们还没有在单一薄膜成分下将它们在令人满意的水平上结合在一起；这是第一阶段的具体目标。既然已经确定了多组分沉积过程本身的可行性，我们将通过仔细和系统地改变源和衬底温度、源-衬底距离和源本身的化学组成等沉积参数来实现这一目标。第一阶段将生产至少与熔融生长单晶一样好的闪烁性能的材料，从而立即用于商业评估。第二阶段比第一阶段有更全面的目标，在这里，我们将寻求在化学成分和物理形态方面对材料进行优化。此外，在第一阶段的结果和大量新的理论支持的指导下，我们将努力了解导致观察到的效应的机制和支配沉积过程本身的动力学因素。认识到它们的最终应用，我们将生长从5x5cm2到50x50cm2的各种尺寸的微柱状薄膜，并通过评估在CBCT和SPECT操作模式下的薄膜性能来展示它们的实用性。最后，我们将通过与这项技术的潜在用户合作的项目来促进商业化。与公共健康相关：广泛可用的低成本CSI：Tl不仅具有极高的闪烁效率，而且可以很容易地制造成用于高分辨率成像的大面积微柱膜，使其成为广泛应用的材料选择。不幸的是，CsI：Tl在其闪烁衰减过程中表现出强烈的余辉成分，在长时间照射后表现出严重的滞后，限制了可实现的能量分辨率以及成像质量和速度。这些缺点有效地阻止了它在放射性核素成像和医用CT等应用中的使用，否则它的低成本可能会产生巨大的经济影响。一种改进的CSI：TL闪烁体，如这里提出的，可以降低关键的救命医疗设备的成本，如X射线CT扫描仪、透视系统和其他依赖快速数据采集的设备。

项目成果

Nondestructive method for quantifying thallium dopant concentrations in CsI:Tl crystals.

用于量化 CsI:Tl 晶体中铊掺杂剂浓度的无损方法。

• DOI: 10.1016/j.apradiso.2013.08.002
• 发表时间: 2013
• 期刊: Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine
• 作者: Miller,StuartR;Ovechkina,ElenaE;Bennett,Paul;Brecher,Charles
• 通讯作者: Brecher,Charles