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，以优化间质光动力疗法(PDT)的PDT剂量。我们探索一种明确的方法来表征光动力疗法的剂量。显式PDT剂量本质上是给定光敏剂的药物浓度和光通量与组织氧合的乘积。为了快速确定体内组织光学性质在治疗波长下的空间分布，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，我们计划开发一种吸收光谱成像系统来确定组织的吸收光谱分布。对吸收光谱的正确分析确定了组织的含氧量，也提供了对前列腺中光敏剂浓度的另一种估计。为了确定光通量的时空分布，我们使用我们现有的体内光剂量学系统，结合多探测器探测器。测量结果可以与使用组织光学性质信息和非均匀介质中合适的光通量算法的计算结果进行比较。我们假设，一旦PDT剂量超过阈值剂量，就会与肿瘤坏死相关。我们还假设在治疗体积(例如，前列腺)内存在光学性质和药物浓度的异质性。这需要作为集成系统一部分的现场PDT剂量测量(光通量速率和药物分布)、反馈和光源调节。通过对PDT剂量的准确计算和优化方法的使用，可以调整光源的权重，达到最有效的PDT剂量分布，既能达到治疗肿瘤的剂量处方，又能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.