Design and characterization of a dead-time regime enhanced early photon projection imaging system.
Design and characterization of a dead-time regime enhanced early photon projection imaging system.
复制标题
DOI：
10.1063/1.5003620
复制
发表时间：
2018-04
期刊：
影响因子：
--
通讯作者：
L. Sinha;M. Fogarty;W. Zhou;A. Giudice;J. Brankov;K. Tichauer
中科院分区：
文献类型：
--
作者：
L. Sinha;M. Fogarty;W. Zhou;A. Giudice;J. Brankov;K. Tichauer
可见光和近红外光在生物组织中的散射降低了对厚度超过100 μm的组织成像的空间分辨率。在这项研究中，提出了一种光学投影成像系统，其特征在于，利用典型的基于单光子雪崩二极管（SPAD）的光子计数模块的死区时间特性。利用该系统，可以衰减对更多散射的晚到达光子的检测，使得可以利用增加的光强度来增强对较少散射的早到达光子的检测，而不受SPAD的最大计数率的阻碍。该系统具有提供生物样品的基于透射率的解剖信息或基于荧光的功能信息（在仪器中略微修改）的潜力，在介观域（0.1- 2cm）中具有改进的分辨率。系统设计，校准，稳定性和性能进行了评估，使用模拟和实验体模研究。所提出的系统允许以更高的频率和更好的信噪比检测非常罕见的早期光子。实验结果表明，在组织等效吸收系数μa = 0.05 mm-1和散射系数μs' = 5 mm-1的4 mm厚体模中，使用早期光子探测与传统探测相比，空间分辨率提高了3.4倍，使用增强早期探测与传统早期光子探测相比，成像时间提高了1000倍。
Scattering of visible and near-infrared light in biological tissue reduces spatial resolution for imaging of tissues thicker than 100 μm. In this study, an optical projection imaging system is presented and characterized that exploits the dead-time characteristics typical of photon counting modules based on single photon avalanche diodes (SPADs). With this system, it is possible to attenuate the detection of more scattered late-arriving photons, such that detection of less scattered early-arriving photons can be enhanced with increased light intensity, without being impeded by the maximum count rate of the SPADs. The system has the potential to provide transmittance-based anatomical information or fluorescence-based functional information (with slight modification in the instrumentation) of biological samples with improved resolution in the mesoscopic domain (0.1-2 cm). The system design, calibration, stability, and performance were evaluated using simulation and experimental phantom studies. The proposed system allows for the detection of very-rare early-photons at a higher frequency and with a better signal-to-noise ratio. The experimental results demonstrated over a 3.4-fold improvement in the spatial resolution using early photon detection vs. conventional detection, and a 1000-fold improvement in imaging time using enhanced early detection vs. conventional early photon detection in a 4-mm thick phantom with a tissue-equivalent absorption coefficient of μa = 0.05 mm-1 and a reduced scattering coefficient of μs' = 5 mm-1.