Polycrystalline Lead Oxide (PbO) photoconductor: physics and application in direct conversion x-ray medical imaging detectors

多晶氧化铅 (PbO) 光电导体：物理原理及其在直接转换 X 射线医学成像探测器中的应用

• 批准号: RGPIN-2015-04532
• 负责人: Reznik, Alla
• 金额: $ 2.04万
• 依托单位: Lakehead University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=682695
• 关键词: Polycrystalline; Lead; Oxide; PbO; photoconductor

Direct conversion x-ray detectors with amorphous selenium (a-Se) layer as x-ray-to-charge transducers revolutionized radiation medical imaging. Indeed, a-Se mammographic detectors show breast image quality superior to other existing commercial detectors. ***Although a-Se properties fit applications in the mammographic energy range, for general radiographic and fluoroscopic applications a-Se has to be replaced by higher Z (atomic number) material. Therefore there is a need for a new material to realize the advantages of direct conversion methods in the diagnostic energy range. This need is addressed here: the objective of the proposed research program is to extend the advances of direct conversion x-ray detectors to fluoroscopic and radiographic applications on the basis of the most promising photoconductor material, namely Polycrystalline Lead Oxide (PbO). The new Lead Oxide Photoconductor technology will achieve higher sensitivity and improved spatial resolution over existing commercial indirect conversion methods. ***PbO has enormous potential for applications in radiographic and fluoroscopic imaging. It has two distinct advantages over a-Se: ***(1) it has higher x-ray detection efficiency than a-Se due to its higher Z and thus permits effective absorption of higher energy x-rays with thinner layer, and ***(2) it has lower electron-hole pair creation energy, and hence a higher x-ray-to-charge conversion gain.***However, PbO photoconductive layers are still experimental-they have not yet achieved conversion efficiency as high as the theoretical limit, and at the present stage of the technology, PbO layers have not yet shown adequate temporal behavior for fluoroscopic applications. Overcoming these challenges requires a comprehensive program on PbO physics and material science to understand the preparation-?fabrication-property relationships in this material and to optimize PbO technology based on this knowledge. The proposed program aims to transfer an improved PbO technology into Active Matrix Flat Panel Imagers (AMFPI) for fluoroscopy and low-cost X-ray light valve (XLV) detectors for radiography. ***The development of PbO-based detector technology is an important scientific and engineering accomplishment in the continuing development of digital x-ray imaging systems. In particular, PbO-based detectors have greater sensitivity at lower x-ray exposures. This has the core benefit of either reducing the incident x-ray dose to acquire a diagnostic image, and thereby improve the overall safety of general radiography and interventional procedures, or to improve disease detectability at typical x-ray exposures. As such, the proposed program will ultimately benefit healthcare in Canada and worldwide. **

采用非晶硒 (a-Se) 层作为 X 射线电荷传感器的直接转换 X 射线探测器彻底改变了辐射医学成像。事实上，a-Se 乳腺 X 光探测器显示出优于其他现有商业探测器的乳腺图像质量。 ***尽管 a-Se 特性适合乳腺 X 线照相能量范围内的应用，但对于一般放射线照相和荧光镜应用，a-Se 必须被更高 Z（原子序数）的材料取代。因此，需要一种新材料来实现直接转换方法在诊断能量范围内的优势。这里解决了这一需求：拟议研究计划的目标是基于最有前途的光电导体材料，即多晶氧化铅（PbO），将直接转换 X 射线探测器的进步扩展到荧光镜和放射线照相应用。与现有的商业间接转换方法相比，新的氧化铅光电导体技术将实现更高的灵敏度和更高的空间分辨率。 ***PbO 在射线照相和荧光成像方面具有巨大的应用潜力。与 a-Se 相比，它具有两个明显的优势：***(1) 由于 Z 值更高，因此比 a-Se 具有更高的 X 射线检测效率，因此可以用更薄的层有效吸收更高能量的 X 射线，并且 * **(2) 它具有较低的电子空穴对生成能，因此具有较高的 X 射线到电荷转换增益。***然而，PbO 光电导层仍处于实验阶段，尚未达到如此高的转换效率作为理论极限，在技术现阶段， PbO 层尚未表现出适合荧光镜应用的足够的时间行为。克服这些挑战需要一个关于 PbO 物理和材料科学的综合计划，以了解这种材料的制备-制造-性能关系，并根据这些知识优化 PbO 技术。 该计划旨在将改进的 PbO 技术转移到用于荧光检查的有源矩阵平板成像仪 (AMFPI) 和用于放射线照相的低成本 X 射线光阀 (XLV) 探测器中。 ***基于 PbO 的探测器技术的发展是数字 X 射线成像系统持续发展中的一项重要科学和工程成就。特别是，基于 PbO 的探测器在较低的 X 射线照射下具有更高的灵敏度。其核心优势在于，可以减少获取诊断图像时的入射 X 射线剂量，从而提高一般放射线照相和介入手术的整体安全性，或者提高典型 X 射线照射下疾病的可检测性。因此，拟议的计划最终将使加拿大和全世界的医疗保健受益。 **