High Resolution Mammography Sensor

说明(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射线接收器的数字射线成像技术。更具体、更有针对性的应用是乳房X光成像(包括乳房断层合成)，这项技术的好处将在后面描述。在这项研究的核心，RMD正在开发用半导体碘化汞(HgI2)的多晶层制造的“直接成像”X射线探测器的工艺。这项工作的一个重要部分将涉及为预定目的定制这些层的电、化学和物理性质。为了利用HgI2作为X射线接收器，它必须与非晶硅(a-Si)薄膜晶体管(TFT)阵列耦合。TFT阵列提供形成完整成像器所必需的像素化、电荷存储和帧读出。为了使数字化乳腺摄影能够充分发挥其潜力，从而产生重大的临床影响，需要先进的X射线检测技术。RMD正在研究一种使用碘化汞(HgI2)作为X射线探测器的“直接”探测方法。HgI2薄膜作为传感器，由于其高X射线阻止能力，以高量子效率探测入射X射线。由于HgI2中形成了电子-空穴对，探测到的x射线图像直接转换为电子电荷图像。由于以最小的横向扩展有效地收集这些电荷，这种方法不会受到在荧光粉中观察到的光扩展效应的影响，因此提供了高检测效率以及高空间分辨率。HgI2具有阻挡效率高、增益大、电荷传输好、稳定性好等特点，是乳房X光摄影的理想选择。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，这使其与日益可用的大尺寸a-Si：H TFT阵列非常相辅相成。RMD计划在两种类型的衬底上沉积和测试关键的HgI2层：1)用于测试电学整体性能的简单导电板，以及2)将提供关键成像数据的一系列a-Si TFT阵列。RMD将执行与层相关的所有制造任务，并在更简单的设备上进行大多数评估。为了协助a-Si TFT任务，RMD已与瓦里安医疗系统公司和密歇根大学的两家合作者合作，提供测试材料和专业知识。密歇根大学的Mitchell Goodsitt博士加入了我们的团队，为高分辨率乳房X光摄影和数字乳房断层合成(DBT)的特定成像要求提供指导。MGH的丹尼尔·科潘斯博士和理查德·摩尔也加入了我们的团队，担任临床顾问。Kopans博士和Richard Moore是乳房X光摄影和DBT方面的专家，他们将就临床目标提供指导和意见，并在适用于数字乳房X光摄影和DBT的条件下对我们的成像仪进行评估。与公共健康相关：RMD正在提议开发一种新型的乳房X光照相X射线探测器，该探测器有望在低曝光水平下实现非常高的空间分辨率和卓越的图像。拟议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.