具有早期光子到达时间的混浊介质中点状荧光内含物的时域几何定位。
Time-domain geometrical localization of point-like fluorescence inclusions in turbid media with early photon arrival times.
作者信息
Pichette Julien, Domínguez Jorge Bouza, Bérubé-Lauzière Yves
出版信息
Appl Opt. 2013 Aug 20;52(24):5985-99. doi: 10.1364/AO.52.005985.
We introduce a novel approach for localizing a plurality of discrete point-like fluorescent inclusions embedded in a thick turbid medium using time-domain measurements. The approach uses early photon information contained in measured time-of-flight distributions originating from fluorescence emission. Fluorescence time point-spread functions (FTPSFs) are acquired with ultrafast time-correlated single photon counting after short pulse laser excitation. Early photon arrival times are extracted from the FTPSFs obtained from several source-detector positions. Each source-detector measurement allows defining a geometrical locus where an inclusion is to be found. These loci take the form of ovals in 2D or ovoids in 3D. From these loci a map can be built, with the maxima thereof corresponding to positions of inclusions. This geometrical approach is supported by Monte Carlo simulations performed for biological tissue-like media with embedded fluorescent inclusions. To validate the approach, several experiments are conducted with a homogeneous phantom mimicking tissue optical properties. In the experiments, inclusions filled with indocyanine green are embedded in the phantom and the fluorescence response to a short pulse of excitation laser is recorded. With our approach, several inclusions can be localized with low millimeter positional error. Our results support the approach as an accurate, efficient, and fast method for localizing fluorescent inclusions embedded in highly turbid media mimicking biological tissues. Further Monte Carlo simulations on a realistic mouse model show the feasibility of the technique for small animal imaging.
我们介绍了一种新颖的方法,用于通过时域测量来定位嵌入在厚浑浊介质中的多个离散点状荧光内含物。该方法利用了源自荧光发射的测量飞行时间分布中包含的早期光子信息。在短脉冲激光激发后,通过超快时间相关单光子计数获取荧光时间点扩展函数(FTPSF)。从几个源 - 探测器位置获得的FTPSF中提取早期光子到达时间。每次源 - 探测器测量都允许定义一个几何轨迹,在该轨迹上可以找到一个内含物。这些轨迹在二维中呈椭圆形,在三维中呈卵形。根据这些轨迹可以构建一个地图,其最大值对应于内含物的位置。这种几何方法得到了对具有嵌入荧光内含物的生物组织样介质进行的蒙特卡罗模拟的支持。为了验证该方法,使用模拟组织光学特性的均匀体模进行了几个实验。在实验中,将填充有吲哚菁绿的内含物嵌入体模中,并记录对激发激光短脉冲的荧光响应。使用我们的方法,可以以低至毫米级的位置误差定位多个内含物。我们的结果支持该方法作为一种准确、高效且快速的方法,用于定位嵌入模拟生物组织的高浑浊介质中的荧光内含物。在真实小鼠模型上进行的进一步蒙特卡罗模拟显示了该技术用于小动物成像的可行性。