Acoustic resolution photoacoustic Doppler velocity measurements in fluids using time-domain cross-correlation
Acoustic resolution photoacoustic Doppler velocity measurements in fluids using time-domain cross-correlation
复制标题
使用时域互相关进行流体中的声学分辨率光声多普勒速度测量
DOI：
10.1117/12.2004742
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Brunker J
中科院分区：
文献类型：
--
作者：
Brunker J
血流测量已使用光声传感的声学分辨率模式进行了演示。这与之前使用光学分辨率模式的流量测量方法不同，后者将最大穿透深度限制为大约 1mm。在这里，我们描述了一种脉冲时间相关光声多普勒技术，该技术本质上是灵活的，适合两种分辨率模式。通过使用激光脉冲对在移动吸收体中生成的光声波形对和使用超声换能器检测到的光声波的互相关来量化多普勒时移。声学分辨率模式是通过使用换能器焦距宽度而不是大照明体积来定义横向空间分辨率。使用短激光脉冲可以以高空间分辨率获得深度分辨测量，为绘制微循环内的血流提供了前景。虽然我们之前的工作仅限于非流体体模，但我们现在展示了在更真实的模拟血液体模中进行的测量，其中包含沿着光学透明管流动的微球流体悬浮液。测量的速度高达 110 mm/s，精度接近已知速度的 1%，分辨率为几 mm/s。速度范围和分辨率可通过激励脉冲分离进行扩展，但最大可测量速度远小于探测器焦束宽度的预期值。还对流速高达 13.5 毫米/秒的血液进行了测量。这是针对减少至正常血细胞比容 5% 的样本；红细胞浓度的增加限制了最大可测量速度，因此浓度超过生理实际血细胞比容 20% 时无法获得结果。造成这种限制的可能原因有多种；这些包括检测器带宽和流动模式的不规则性。使用具有更高中心频率和更大带宽的探测器以及具有更窄直径的管可以获得更好的结果。
Blood flow measurements have been demonstrated using the acoustic resolution mode of photoacoustic sensing. This is unlike previous flowmetry methods using the optical resolution mode, which limits the maximum penetration depth to approximately 1mm. Here we describe a pulsed time correlation photoacoustic Doppler technique that is inherently flexible, lending itself to both resolution modes. Doppler time shifts are quantified via cross-correlation of pairs of photoacoustic waveforms generated in moving absorbers using pairs of laser light pulses, and the photoacoustic waves detected using an ultrasound transducer. The acoustic resolution mode is employed by using the transducer focal width, rather than the large illuminated volume, to define the lateral spatial resolution. The use of short laser pulses allows depth-resolved measurements to be obtained with high spatial resolution, offering the prospect of mapping flow within microcirculation. Whilst our previous work has been limited to a non-fluid phantom, we now demonstrate measurements in more realistic blood-mimicking phantoms incorporating fluid suspensions of microspheres flowing along an optically transparent tube. Velocities up to 110 mm/s were measured with accuracies approaching 1% of the known velocities, and resolutions of a few mm/s. The velocity range and resolution are scalable with excitation pulse separation, but the maximum measurable velocity was considerably smaller than the value expected from the detector focal beam width. Measurements were also made for blood flowing at velocities up to 13.5 mm/s. This was for a sample reduced to 5% of the normal haematocrit; increasing the red blood cell concentration limited the maximum measurable velocity so that no results were obtained for concentrations greater than 20% of a physiologically realistic haematocrit. There are several possible causes for this limitation; these include the detector bandwidth and irregularities in the flow pattern. Better results are obtained using a detector with a higher centre frequency and larger bandwidth and tubes with a narrower diameter.
登录
查看更多内容
影响因子：
2.4
作者：
Brunker, Joanna;Beard, Paul
通讯作者：
Beard, Paul
模拟血液模型中的脉冲光声多普勒血流测量
DOI：
--
发表时间：
2011
期刊：
BiOS
影响因子：
--
作者：
J. Brunker;P. Beard
通讯作者：
P. Beard
DOI：
--
发表时间：
2009
期刊：
影响因子：
--
作者：
Hao F. Zhang
通讯作者：
Hao F. Zhang
使用光声多普勒测量对血流进行同步空间和光谱测绘。
影响因子：
3.5
作者：
A. Sheinfeld;S. Gilead;A. Eyal
通讯作者：
A. Eyal
T 管中的流速测量。
DOI：
--
发表时间：
1972
期刊：
影响因子：
--
作者：
J. Strachan;B. Ahlborn;J. Huni
通讯作者：
J. Huni