High Resolution Mammography Sensor

描述（由申请人提供）：辐射监测设备公司（RMD）正在开发一种基于半导体x射线受体的数字放射成像技术。更具体，更有针对性的应用是乳房x线摄影成像（包括乳房断层合成），该技术的好处将在后面描述。在这项研究的核心，RMD正在开发制造“直接成像”x射线探测器的工艺，该探测器由半导体碘化汞（HgI2）的多晶层制成。这项工作的一个重要部分将涉及定制这些层的电学、化学和物理性质，以达到预期的目的。为了利用HgI2作为x射线受体，它必须与非晶硅（a-Si）薄膜晶体管（TFT）阵列耦合。TFT阵列提供必要的像素化、电荷存储和帧读出，以形成一个完整的成像仪。为了使数字乳房x线摄影能够充分发挥其潜力，从而产生重大的临床影响，x射线检测技术需要得到改进。RMD正在研究一种使用碘化汞（HgI2）作为x射线探测器的“直接”检测方法。HgI2薄膜作为传感器，由于其高x射线阻挡能力，以高量子效率检测入射的x射线。由于HgI2中电子-空穴对的形成，检测到的x射线图像直接转换为电子电荷图像。由于这些电荷的有效收集和最小的横向扩散，这种方法不会受到在荧光粉中观察到的光扩散效应的影响，因此提供了高检测效率和高空间分辨率。HgI2具有停止效率高、增益大、电荷输运好、稳定性好等接近理想的特点。最后，RMD提出的沉积HgI2薄膜的方法具有很高的成本效益，并且可以很容易地覆盖大面积，使其与日益可用的大尺寸a-Si:H TFT阵列非常互补。RMD计划在两种类型的衬底上沉积和测试关键的HgI2层：1)用于测试电体特性的简单导电板，以及2)一系列将提供关键成像数据的a- si TFT阵列。RMD将执行与层相关的所有制造任务，并对较简单的设备进行大多数评估。为了帮助完成a-Si TFT任务，RMD与瓦里安医疗系统公司和密歇根大学合作，提供测试材料和专业知识。密歇根大学的Mitchell goodsit博士加入了我们的团队，为高分辨率乳房x线摄影和数字乳腺断层合成（DBT）的具体成像要求提供指导。MGH的Daniel Kopans医生和Richard Moore医生也加入了我们的团队，担任临床顾问。Kopans博士和Richard Moore博士是乳腺x线照相术和DBT的专家，他们将为临床目标提供指导和输入，并在适用于数字乳房x线照相术和DBT的条件下评估我们的成像人员。公共卫生相关性：RMD正在建议开发一种新型乳房x射线检查探测器，该探测器有望在低暴露水平下获得非常高的空间分辨率和卓越的图像。所提出的制造技术既具有成本效益，又易于扩展，两者都有助于消除阻碍技术采用的制造障碍。

DESCRIPTION (provided by applicant): Radiation Monitoring Devices (`RMD') is developing a digital radiographic imaging technology that is based upon a semiconductor x-ray receptor. The more specific, targeted application is mammographic imaging (including breast tomosynthesis) for which the benefits of this technology will later be described. At the core of this research, RMD is developing the process for creating `direct imaging' x-ray detectors fabricated from polycrystalline layers of the semiconductor mercuric iodide (HgI2). A significant part of this work will involve tailoring the electrical, chemical and physical properties of these layers for the intended purpose. To utilize HgI2 as an x-ray receptor, it must be coupled with an amorphous silicon (a-Si) thin film transistor (TFT) array. The TFT array provides pixelation, charge storage and frame readout necessary to form a complete imager. In order to enable digital mammography to achieve its full potential and thereby, have a major clinical impact, x-ray detection technology needs to be advanced. RMD is investigating a `direct' detection method using mercuric iodide (HgI2) as the x-ray detector. The HgI2 film acts as the sensor, detecting the incoming x-rays with high quantum efficiency due to its high x-ray stopping power. The detected x-ray image is converted directly into an electronic charge image due to the formation of electron-hole pairs in HgI2. Due to efficient collection of these charges with minimal lateral spreading, this approach does not suffer from the light spreading effects observed in phosphors and thereby, provides high detection efficiency as well as high spatial resolution. HgI2 has nearly ideal characteristics for mammography such as high stopping efficiency, large gain, good charge transport, and good stability. Finally, the method by which RMD is proposing to deposit the HgI2 films is highly cost effective and can be used to readily cover large areas, making it very complimentary to the large sized a-Si:H TFT arrays that are increasingly becoming available. RMD plans to deposit and test the key HgI2 layers on two types of substrates: 1) simple conductive plates for testing electrical bulk properties, and 2) a range of a-Si TFT arrays that will provide the key imaging data. RMD will perform all the fabrication tasks associated with the layers and conduct most evaluations on the simpler devices. To aid with the a-Si TFT tasks, RMD has joined with two collaborators Varian Medical Systems and the University of Michigan to provide materials and expertise with testing. Dr. Mitchell Goodsitt of the University of Michigan has joined our team to provide guidance on the specific imaging requirements for high resolution mammography and digital breast tomosynthesis (DBT). Dr. Daniel Kopans and Richard Moore of MGH have also joined our team as clinical consultants. Dr. Kopans and Richard Moore are specialists in mammography and DBT and will provide guidance and input on clinical goals and evaluate our imagers under conditions applicable to digital mammography and DBT. PUBLIC HEALTH RELEVANCE: RMD is proposing to develop a new type of mammography x-ray detector that holds the promise of very high spatial resolution and superior images at low exposure levels. The proposed fabrication technique is both cost effective and readily scaleable, both helping to remove manufacturing barriers that can impede adoption of technology.