一种用于小动物本征和荧光成像的具有双波长检测功能的多视角时域非接触式扩散光学断层扫描仪。

A multi-view time-domain non-contact diffuse optical tomography scanner with dual wavelength detection for intrinsic and fluorescence small animal imaging.

作者信息

Lapointe Eric, Pichette Julien, Bérubé-Lauzière Yves

机构信息

Laboratoire TomOptUS, Département de génie électrique et de génie informatique, Université de Sherbrooke, 2500 boul. Université, Sherbrooke, Québec J1K 2R1, Canada.

出版信息

Rev Sci Instrum. 2012 Jun;83(6):063703. doi: 10.1063/1.4726016.

Abstract

We present a non-contact diffuse optical tomography (DOT) scanner with multi-view detection (over 360°) for localizing fluorescent markers in scattering and absorbing media, in particular small animals. It relies on time-domain detection after short pulse laser excitation. Ultrafast time-correlated single photon counting and photomultiplier tubes are used for time-domain measurements. For light collection, seven free-space optics non-contact dual wavelength detection channels comprising 14 detectors overall are placed around the subject, allowing the measurement of time point-spread functions at both excitation and fluorescence wavelengths. The scanner is endowed with a stereo camera pair for measuring the outer shape of the subject in 3D. Surface and DOT measurements are acquired simultaneously with the same laser beam. The hardware and software architecture of the scanner are discussed. Phantoms are used to validate the instrument. Results on the localization of fluorescent point-like inclusions immersed in a scattering and absorbing object are presented. The localization algorithm relies on distance ranging based on the measurement of early photons arrival times at different positions around the subject. This requires exquisite timing accuracy from the scanner. Further exploiting this capability, we show results on the effect of a scattering hetereogenity on the arrival time of early photons. These results demonstrate that our scanner provides all that is necessary for reconstructing images of small animals using full tomographic reconstruction algorithms, which will be the next step. Through its free-space optics design and the short pulse laser used, our scanner shows unprecedented timing resolution compared to other multi-view time-domain scanners.

摘要

我们展示了一种具有多视角检测(超过360°)的非接触式漫射光学层析成像(DOT)扫描仪,用于在散射和吸收介质(特别是小动物)中定位荧光标记物。它依赖于短脉冲激光激发后的时域检测。超快时间相关单光子计数和光电倍增管用于时域测量。为了收集光,七个自由空间光学非接触双波长检测通道(总共包括14个探测器)围绕着对象放置,从而能够在激发波长和荧光波长下测量时间点扩展函数。该扫描仪配备了一对立体相机,用于以三维方式测量对象的外形。表面测量和DOT测量使用同一激光束同时进行。讨论了扫描仪的硬件和软件架构。使用体模来验证该仪器。给出了浸入散射和吸收对象中的荧光点状内含物的定位结果。定位算法基于对早期光子到达对象周围不同位置的时间测量来进行距离测距。这需要扫描仪具备精确的定时精度。进一步利用这一能力,我们展示了散射不均匀性对早期光子到达时间的影响的结果。这些结果表明,我们的扫描仪提供了使用全层析重建算法重建小动物图像所需的一切,而这将是下一步的工作。通过其自由空间光学设计和所使用的短脉冲激光,我们的扫描仪与其他多视角时域扫描仪相比显示出前所未有的定时分辨率。

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