Image Reconstruction Algorithms for Optical Tomography

描述（由申请人提供）：所提出的研究的目标是解决开发具有大数据集的非接触式光学断层扫描（OT）的计算效率高的图像重建算法的问题。具体来说，我们打算设计快速算法的三维图像重建在megavoxel的水平。为了实现这一目标，我们将利用研究人员在OT图像重建分析方法上取得的最新进展。这些算法将通过计算机模拟进行系统研究，并通过模型系统的实验进行验证。该方法允许将由于算法误差引起的效应与由于测量误差引起的效应分离。计划中的“台式”实验是算法开发之后但在临床研究之前的下一个合乎逻辑的步骤，并且对于该提案的成功至关重要。具体目标是：（1）建立多光谱非接触光学层析成像系统。这将需要升级现有的单波长连续波OT系统。计划中的改进包括电子倍增CCD摄像机，用于更快的数据采集和改善的信噪比;使用光学开关二极管激光器在三个波长处的照明;以及使用脉冲钛蓝宝石激光器进行吸收和散射的光谱测量的时间分辨透射测量;（2）实施和优化具有大数据集的OT的快速图像重建算法。计划的研究将首先集中在吸收的非线性重建。然后，重点将转移到同时使用多光谱和多频率数据的吸收和散射的线性和非线性重建。在体模实验验证之前，将使用数值模拟对算法进行测试和优化;（3）使用体模评估上述重建算法的性能。重建算法将在一组实验中进行测试，这些实验与特定目标2下进行的数值模拟并行。将在组织等效体模中评估图像质量。我们将利用平行板成像的几何结构，这是经常采用的光学乳房摄影。这项研究的结果预计将影响非接触式光学断层扫描的临床有用的仪器的设计。

DESCRIPTION (provided by applicant): The goal of the proposed research is to solve the problem of developing computationally efficient image reconstruction algorithms for noncontact optical tomography (OT) with large data sets. Specifically, we intend to devise fast algorithms for three-dimensional image reconstruction at the megavoxel level. To achieve this goal, we will exploit recent advances obtained by the Investigators on analytic methods for image reconstruction in OT. The algorithms will be systematically studied by computer simulations and validated by experiments in model systems. This approach allows the separation of effects due to algorithmic errors from those due to measurement errors. The planned "benchtop" experiments are the next logical step after algorithm development but before clinical studies and are critical to the success of this proposal. The specific aims are to (1) Construct instrumentation for multispectral noncontact optical tomography. This will entail upgrading an existing single-wavelength continuous-wave OT system. The planned enhancements include an electron multiplying CCD camera for faster data acquisition and improved signal to noise; illumination at three wavelengths using optically switched diode lasers; and time-resolved transmission measurements using a pulsed Ti-sapphire laser for spectroscopic measurements of absorption and scattering; (2) Implement and optimize fast image reconstruction algorithms for OT with large data sets. The planned studies will first focus on nonlinear reconstruction of the absorption. The focus will then shift to simultaneous linear and nonlinear reconstruction of absorption and scattering using multispectral and multifrequency data. The algorithms will be tested and optimized using numerical simulations prior to experimental validation in phantoms; (3) Evaluate the performance of the above reconstruction algorithms using phantoms. The reconstruction algorithms will be tested in a set of experiments which parallel the numerical simulations carried out under specific aim 2. Image quality will be assessed in tissue-equivalent phantoms. We will utilize the parallel plate imaging geometry which is often employed in optical mammography. The results of this research are expected to impact the design of clinically useful instruments for noncontact optical tomography.