Pb-Qdot Direct Gamma Detectors

描述（由申请人提供）：辐射探测器的一个关键性能是停止功率，它描述了探测器收集辐射的效率。为了使患者的剂量最小化，增加停止功率是有帮助的，因为停止功率与获得高质量患者图像所需的剂量成反比。停止功率与探测器材料的有效原子序数密切相关。放射设备的设计者更喜欢用具有非常高的有效原子序数的材料，比如铅，来制造辐射探测器。不幸的是，大多数具有较高阻挡能力的元素都不适合作为辐射探测器材料，因为电荷（由探测器中的辐射产生）不能轻易地从探测器材料中移出。因此，放置在探测器外部的仪器无法测量由探测器材料中的辐射引起的电荷。将电荷从探测器内部移到外部世界（在那里它可以被测量）的过程称为“电荷传输”。在第一阶段，我们表明，通过将创造高停止功率的目标与有利电荷输运的挑战分开，有可能解决探测器规格的难题。这种分离是通过创建一个矩阵来实现的，在这个矩阵中，由高原子序数材料（即硫化铅）制成的量子点散布在硅基体中。量子点是原子的小集合，它们的电学特性与这些原子的整体版本不同。我们利用硫化铅的高停止功率特性和量子点的良好电学特性，将辐射高效率地转化为电荷。我们使用硅矩阵将电荷有效地从量子点传输到硅矩阵表面，这样电荷就可以被放大并向外部仪器提供强信号。使用硅作为主矩阵的另一个好处是，我们证明了我们可以在与辐射探测器相同的材料上构建电路元件（例如，放大器元件）。在证明了可行性之后，我们的下一个目标是通过优化探测器的质量，为产品的商业化做好准备。这是首个将纳米科技成功应用于直接转换辐射探测的项目。它有望减少对病人的辐射剂量，降低医疗成本。除了诊断放射学市场之外，该平台技术还将用于国土安全和消费者和国防市场的广谱监视，并可能与太阳能行业交叉施肥。

DESCRIPTION (provided by applicant): A critical property of radiation detectors is stopping power, which describes the efficiency of the detector in collecting radiation. In order to minimize patient dose, it is helpful to increase stopping power, since stopping power is inversely related to the dose required for obtaining high-quality patient images. Stopping power is strongly related to the effective atomic number of the detector material. Designers of radiological devices would prefer to build radiation detectors from materials with very high effective atomic numbers, such as lead. Unfortunately, most elements with higher stopping powers are not good candidates as radiation detector materials, because electrical charges (created by radiation in the detector) cannot be easily moved out of the detector material. As a result, instruments placed outside the detector are unable to measure the charges caused by radiation in the detector material. The process of removing charge from the inside of the detector into the outside world (where that it can be measured) is called "charge transport". In Phase I, we showed that it was possible to cut the Gordian knot of detector specification, by separating the goal of creating high stopping power from the challenge of favorable charge transport. This separation was accomplished by creating a matrix in which quantum dots made of high-atomic- number material (i.e., lead sulfide) were interspersed within a silicon matrix. Quantum dots are small collections of atoms that have different electrical properties than the bulk versions of these atoms. We used the high stopping power property of the lead sulfide, and the favorable electrical properties of the quantum dots, to convert radiation into charge with high efficiency. We used the silicon matrix to transport the charges effectively from the quantum dots to the surface of the silicon matrix, so that the charges could be amplified and provide strong signals to outside instruments. An additional benefit of using silicon as the host matrix was that we showed we could build circuit elements (e.g., amplifier components) on the same material as the radiation detector. Having demonstrated feasibility, our next goal is to ready the product for commercialization by optimizing detector quality. This project represents the first successful application of nanotechnology to direct-conversion radiation detection. It promises to reduce radiation dose to patients and to lower health care costs. In addition to the diagnostic radiology market, the platform technology will be useful for homeland security and broad-spectrum surveillance for the consumer and defense markets, with potential cross-fertilization to the solar power industry.