Real-Time PDT Dosimetry with Feedback Light Delivery

描述（由申请人提供）：本提案的总体目标是开发一种集成系统来优化间质性光动力治疗（PDT）的PDT剂量。我们探索了一种明确的方法来表征PDT剂量。显式PDT剂量本质上是给定光敏剂和组织氧合的药物浓度和光影响的产物。为了快速确定治疗波长下组织光学特性在体内的空间分布，我们计划开发一种由多个探测器和点源组成的机动装置。为了确定体内药物浓度的空间分布，我们计划开发一种荧光光谱成像系统。此外，我们计划开发一个吸收光谱成像系统，以确定组织的吸收光谱分布。适当的分析吸收光谱确定组织氧合，也提供了另一个估计光敏剂浓度在前列腺。为了确定光通量的时空分布，我们使用了现有的体内光剂量测定系统，结合了多探测器探针。测量结果可以与使用有关组织光学性质的信息和在非均质介质中适当的光通量算法的计算结果进行比较。我们假设PDT剂量一旦超过阈值剂量，与肿瘤坏死有关。我们还假设在治疗体积内（例如前列腺）存在光学性质和药物浓度的异质性。这需要原位PDT剂量测定（光通量和药物分布）、反馈和光源调整作为集成系统的一部分。通过对PDT剂量的精确计算和优化方法的应用，我们可以调整光源的权重，使PDT剂量分布达到最有效的程度，使肿瘤治疗达到剂量处方，同时避免对正常结构的损伤。

DESCRIPTION (provided by applicant): The overall objective of this proposal is to develop an integrated system to optimize PDT dose for interstitial photodynamic therapy (PDT). We explore an explicit method to characterize the PDT dose. The explicit PDT dose is essentially the product of drug concentration and light fluence for a given photosensitizer and tissue oxygenation. To quickly determine the spatial distribution of tissue optical properties in-vivo at the treatment wavelength, we plan to develop a motorized device consists of multiple detectors and point sources. To determine the spatial distribution of drug concentration in-vivo, we plan to develop a fluorescence spectroimaging system. In addition, we plan to develop an absorption spectroimaging system to determine the distribution of absorption spectra of tissue. Proper analysis of the absorption spectrum determines tissue oxygenation, and also provides another estimate of the photosensitizer concentration in the prostate gland. To determine the temporal-spatial distribution of light fluence rate, we use our existing in-vivo light dosimetry system in combination the multi-detector probes. The measured results can be compared with calculations using information about tissue optical properties and a suitable light fluence algorithm in heterogeneous medium. We hypothesize that PDT dose, once above a threshold dose, correlates to the tumor necrosis. We also hypothesize that there are heterogeneities of both optical properties and drug concentration within the treatment volume (e.g., prostate gland). This requires in-situ PDT dosimetry (of light fluence rate and drug distribution), feedback, and light source adjustment as part of the integrated system. With an accurate calculation of the PDT dose and the use of optimization methods, we can adjust the light source weights to achieve the most efficacious distribution of PDT dose, treating the tumor to dose prescription yet avoiding injury to normal structure.