Devi C Usha, Vasu R M, Sood A K
Indian Institute of Science, Department of Instrumentation, Bangalore, India.
J Biomed Opt. 2006 May-Jun;11(3):34019. doi: 10.1117/1.2209012.
We investigate the modulation of an optical field caused by its interaction with an ultrasound beam in a tissue mimicking phantom. This modulation appears as a modulation in the intensity autocorrelation, which is measured by a photon counting correlator. The factors contributing to the modulation are: 1. amplitude of vibration of the particles of the tissue, 2. refractive index modulation, and 3. absorption coefficient in the region of the tissue intercepted by the ultrasound beam and light. We show in this work that a significant part of the contribution to this modulation comes from displacement of the tissue particles, which in turn is governed by the elastic properties of the tissue. We establish, both through simulations and experiments using an optical elastography phantom, the effects of the elasticity and absorption coefficient variations on the modulation of intensity autocorrelation. In the case where there is no absorption coefficient variation, we suggest that the depth of modulation can be calibrated to measure the displacement of tissue particles that, in turn, can be used to measure the tissue elasticity.
我们研究了在仿组织体模中，光场与超声束相互作用所引起的光场调制。这种调制表现为强度自相关的调制，由光子计数相关器进行测量。对这种调制有贡献的因素包括：1. 组织颗粒的振动幅度；2. 折射率调制；3. 超声束和光所截获的组织区域中的吸收系数。我们在这项工作中表明，这种调制的很大一部分贡献来自组织颗粒的位移，而组织颗粒的位移又由组织的弹性特性所决定。我们通过使用光学弹性成像体模进行模拟和实验，确定了弹性和吸收系数变化对强度自相关调制的影响。在没有吸收系数变化的情况下，我们建议可以校准调制深度以测量组织颗粒的位移，而组织颗粒的位移又可用于测量组织弹性。
