Focusing Ultrasound (FUS) can be used to modulate diffusing light in tissue. In this method, diffused photons are modulated in the ultrasound focus area. Detecting these FUS modulated (or tagged) photons can provide spatially accurate information from the focus area. However, probably the biggest challenge in this method is to enable sufficient tagging photons since most of the illuminated and detected photons do not propagate thru the FUS target area resulting in a low number of tagged photons when compared to the background unmodulated light. Therefore, current applications utilizing such hybrid technique are still limited. Our study aims to optimize illumination and detection of photons that propagate through a FUS target area by adjusting the relative position and angle of a light source-detector pair. For the simulations, the K-wave toolbox was utilized to calculate the nonlinear acoustic pressure field in the discretized numerical model from the FUS source. Furthermore, light propagation in the model is simulated using an open-source Monte Carlo algorithm. The model design is a backward detection mode which is suitable for direct application to the human body.
|