A simulation study of the effect of transducer position on photoacoustic spectrum analysis for stochastic microstructure

Photoacoustic (PA) imaging is a potential new biomedical imaging technique with combined advantages of ultrasonography's good resolution and high contrast of optical imaging. The spectrum parameters obtained from photoacoustic spectrum analysis (PASA) have been found to have the relationship with tissue microstructure. However, the effects of transducer positions on PASA have not been studied yet. A simplified 2-D simulation model is presented using Monte Carlo method and finite-difference time-domain (FDTD) method to detect PA signals from various transducer positions generated by microspheres with certain radius which have uniformly random positions within the region of interest. PASA is applied and the spectral slope from different distances and angles is extracted and compared with that from microspheres of different radius but at the same positions. It finds that PA spectral slope extracted from some angles show better relationship with dimensions of the microspheres than that from other angles. While changing the detection radius does not have a significant effect on the result.