Non-contact methodology to detect surface displacements for photoacoustic imaging reconstruction

用于光声成像重建的表面位移检测的非接触方法

• 批准号: 445351-2012
• 负责人: Kolios, Michael
• 金额: $ 1.82万
• 依托单位: Ryerson University
• 依托单位国家: 加拿大
• 项目类别: Engage Grants Program
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=511143
• 关键词: Non; contact; methodology; detect; surface

In commercial photoacoustic systems, a non-ionizing laser pulse propagates through media biomaterials or tissue and heats a target (i.e. optical absorbers in biomaterials, hemoglobin in tissue blood vessels). The absorbed heat by the target causes a transient thermal elastic expansion, which creates a pressure wave that propagates to the surface or skin through a coupling medium and that is detected by an ultrasound transducer to form an image of the target. There are many disadvantages of using such a coupling medium. First, the coupling medium can scatter and attenuate the light pulse and thereby reduce the pressure wave generated, decreasing the signal to noise ratio (SNR) of the system. Second, the coupling medium attenuates the pressure wave as it propagates through the coupling medium. Third, the use of a coupling medium is a step that can complicate an experimental set-up due to the low viscosity of the gel and the fact that it is hard to keep in stationary, which clinically, many patients find inconvenient, messy, and lengthens the imaging procedure. In this project, a more direct photoacoustic imaging system will be developed without using a coupling medium. A continuous laser beam will be focused on the surface. The surface's motion causes a Doppler shift in the reflected beam which can be detected using interferometry techniques. This technological development will also guide the subsequent design and construction of a laser interferometry photoacoustic system.

在商业光声系统中，非电离激光脉冲通过介质生物材料或组织传播并加热目标（即生物材料中的光学吸收剂，组织血管中的血红蛋白）。被目标吸收的热量引起瞬态热弹性膨胀，产生压力波，该压力波通过耦合介质传播到表面或皮肤，并被超声波换能器检测到，形成目标的图像。使用这种耦合介质有许多缺点。首先，耦合介质对光脉冲进行散射和衰减，从而减小产生的压力波，降低系统的信噪比。其次，耦合介质使压力波在耦合介质中传播时发生衰减。第三，耦合介质的使用会使实验设置复杂化，因为凝胶粘度低，而且很难保持静止，这在临床上，许多患者发现不方便、混乱，并延长了成像过程。在这个项目中，一个更直接的光声成像系统将开发不使用耦合介质。连续的激光束将聚焦在表面上。表面的运动引起反射光束的多普勒频移，这可以用干涉测量技术检测到。这项技术的发展也将指导后续激光干涉光声系统的设计和建设。