TIME-GATED OPTICAL MAMMOGRAPHY

在这项研究中，我们建议开发一种近红外(NIR)时间- 用于乳腺肿瘤检测的分辨率光学成像系统 组织。早期发现乳腺癌是一项重大的公共事业 健康问题。X光乳房X光摄影的标准方法受到 需要让病人暴露在电离辐射中。因为激烈的 组织对光的散射，产生高质量的能力 基于光学测量的图像将需要评估 高度分散的信号。 这一系统的开发将沿着两个问题领域进行；数据 收集资料并进行数据分析。该实验计划将涉及一项 模型散射介质(微观胶乳)的系统研究 琼脂中的珠子)，其中将放置幻影。数据收集将 涉及执行一维和二维表面扫描 利用时间分辨(皮秒和飞秒)近红外激光进行源定位 来源)，在某些情况下，采用与时间无关的测量方案。这个 散射粒子的大小和数密度将改变为 探索一系列散射介质(从高度向前定向到 近各向同性散射)。结构简单、规则的介质 首先，我们将学习几何学，从而研究 越来越复杂的媒体。在此之后，组织样本将 正在进行研究，包括那些已知含有癌症病变的。 分析程序将由三部分组成。第一 讨论了高散射中光子输运的数值模拟 媒体。利用蒙特卡罗和其他数值方法，空间上的 探测到的光子通量作为源-探测器函数的分布 介质的配置、照明方案和几何形状 模特儿。此外，反射和折射的重要性 我们将研究内部边界和外部的光子，如 是介质复杂程度的函数。反问题的解 将通过求解一个线性微扰方程来进行评估 最近开发出来的。将采用多种方法来解决 问题包括梯度下降方法和可以容易地 整合约束解决方案所需的先验信息。在……里面 此外，利用多重网格技术的混合方法将是 学习。由于逆问题固有的不适定性， 我们还建议研究各种策略，这些策略可以产生 必要的先验信息。已经确定了几个，但 还需要进一步的开发和测试。 作为一个团队，我们在每个主要问题上都有相当的专业知识 严格执行这一计划必须考虑的领域。 基本上，所需的所有主要实验设备都在 现场有场地和操作人员，以及训练有素的技术人员。在……里面 此外，我们可以直接访问重要的计算设施 对这个项目来说是必不可少的。此外，还开展了广泛的前期工作 所有主要问题领域都已进行，并取得了成果 证实了拟议研究的可行性。

In this study we propose the development of a near infrared (NIR) time- resolved optical imaging system for the detection of tumors in breast tissue. The early detection of cancer of the breast is a major public health issue. The standard method of X-ray mammography suffers from the need to expose patients to ionizing radiation. Because of the intense scattering of light by tissue, the ability to generate high quality images based on an optical measurement will require the need to evaluate signals which have been highly scattered. Development of this system will proceed along two problem areas; data collection and data analysis. The experimental program will involve a systematic investigation of model scattering media (microscopic latex beads in agar) in which phantoms will be placed. Data collection will involve performing one- and two-dimensional surface scans at multiple source locations using time-resolved (pico- and femtosecond NIR laser sources) and, in some cases, time-independent measurement schemes. The size and number density of the scattering particles will be varied to explore a range of scattering media (from highly forward directed to nearly isotropic scattering). Media having simple structures and regular geometries will be studied, initially, leading to the investigation of increasingly more complex media. Following this, tissue specimens will be studied, including those known to contain cancerous lesions. The analytical program will consist of the three parts. The first concerns the numerical modeling of photon transport in highly scattering media. Using Monte Carlo and other numerical methods, the spatial distribution of detected photon fluxes as a function of source-detector configurations, illumination scheme, and geometry of the medium will be modeled. In addition, the importance of reflection and refraction of photons at internal boundaries and at the exterior will be studied, as a function of complexity of the medium. Solution of the inverse problem will be evaluated by solving a linear perturbation equation we have recently developed. A variety of methods will be employed to solve the problem including gradient decent methods and methods which can readily incorporate apriori information needed to constrain the solution. In addition, hybrid methods which make use of multigrid techniques will be studied. Because of the inherent ill-posedness of the inverse problem, we also propose to examine a variety of strategies which can yield the necessary apriori information. Several have already been identified but further development and testing is needed. As a group, we have considerable expertise in each of the major problem areas that must be considered to rigorously pursue this program. Essentially all of the major experimental facilities required are in place and operational, and trained technical personnel are on-site. In addition, we have direct access to significant computing facilities that are essential to this program. Further, extensive preliminary work in all the major problem areas has been conducted, and results obtained have substantiated the feasibility of the proposed studies.