Analytical and Computational Tools for Long-Pulse Photoacoustics

长脉冲光声学的分析和计算工具

• 批准号: RGPIN-2016-04190
• 负责人: Baddour, Natalie
• 金额: $ 2.4万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709043
• 关键词: Analytical; Computational; Tools; Long; Pulse; Analytical; Computational; Tools; Long; Pulse

Photoacoustic signal generation is a technique which has demonstrated great potential for non-invasive medical tomography. With this technique, a short-pulse of laser energy is used on a sample. The absorbed energy produces a small temperature rise, which in turn induces a change in pressure inside the sample due to thermal expansion. This pressure acts as a source of ultrasound waves which can be detected by ultrasound detectors positioned outside the sample. Since there is a large difference between how blood and surrounding tissue absorb the light energy, this provides a way to look for anomalies in the tissue. This approach is thus suitable for imaging of the micro-vascular system, tumour detection or tissue characterization. The general field of biomedical photoacoustics has largely been based on using very short laser pulses. The short-pulse approach offers computational advantages but also many difficulties with instrumentation and radiation exposure limits. To overcome these difficulties, a methodology has emerged that uses linearly frequency modulated waves of light instead of short pulses to generate the ultrasound wave. This technique is referred to as frequency domain photoacoustics. With this approach that uses longer pulses, many of the modelling and computation approaches on which pulsed photoacoustics is based must be re-examined. More recently, pulse compression techniques of radar have been implemented with frequency domain photoacoustics, whereby the acquired acoustic signal is cross-correlated with the generating light signal. This methodology has been successfully demonstrated experimentally, however many analytical and computational questions remain as pulse-compression radar has not been analyzed or optimized for a photoacoustic application. The questions that the proposed research will address are: Which modelling and computation approaches of pulsed photoacoustics can be retained for frequency domain photoacoustics? How can pulse-compression radar approaches be used effectively to produce images based on frequency domain photoacoustic measurements? Can probing (input) waveforms be designed to achieve (i) a better signal-to-noise ratio (ii) more information (iii) information that is useful for the reconstruction of image? The goal of this research is the development of photoacoustic radar imaging modelling and computational methodologies which hold the promise for sensitive diagnostics of cancerous lesions in, for example, a human breast. Improved modelling and computational approaches, in addition to better waveform design are required to achieve these diagnostic and imaging objectives, and as such form the goals of the proposed research.

光声信号产生是一种技术，它显示出非侵入性医学断层扫描的巨大潜力。使用此技术，样品中使用了短脉冲激光能量。吸收的能量会产生较小的温度升高，从而导致由于热膨胀而导致样品内部压力的变化。该压力充当超声波的来源，可以通过位于样品外的超声检测器检测到。由于血液和周围组织如何吸收光能之间存在很大的差异，因此这提供了一种寻找组织中异常的方法。因此，这种方法适用于微血管系统，肿瘤检测或组织表征的成像。 生物医学光声学的一般领域主要基于使用非常短的激光脉冲。短脉冲方法提供了计算优势，但在仪器和辐射暴露极限方面也有许多困难。为了克服这些困难，出现了一种方法，该方法使用线性频率调制的光波而不是短脉冲来产生超声波。 该技术称为频域光声学。使用这种使用较长脉冲的方法，必须重新检查脉冲光声的许多建模和计算方法。 最近，雷达的脉冲压缩技术已通过频域光声实现，从而，获得的声学信号与生成的光信号交叉相关。 该方法已成功地通过实验证明，但是许多分析和计算问题仍然存在，因为尚未分析或优化用于光声应用的脉冲压缩雷达。 拟议的研究将解决的问题是：频率域光声学可以保留脉冲光声的哪种建模和计算方法？如何有效地使用脉冲压缩雷达方法来基于频域光声测量结果产生图像？是否可以设计探测（输入）波形以实现（i）更好的信噪比（ii）更多信息（iii）信息，这些信息（iii）对于图像的重建有用？ 这项研究的目的是开发光声雷达成像建模和计算方法，这些方法可以使癌变敏感诊断，例如人类乳腺癌的敏感诊断。除了更好的波形设计外，还需要改进的建模和计算方法来实现这些诊断和成像目标，并因此构成了拟议研究的目标。