Photoacoustic image-guided drug delivery in the prostate

Image guided drug delivery is a novel strategy that combines the effect of therapy and visibility into one system. Here we apply photoacoustic (PA) imaging to visualize the drug delivery process, and perform a simulation study on monitoring the photosensitizer concentration in a prostate tumor during photodynamic therapy (PDT). A 3D optical model of the human prostate is developed, and the light absorption distribution in the prostate is estimated by the Monte Carlo simulation method. The filtered back-projection algorithm is used to reconstruct PA images. PA images of transurethral laser/transrectal ultrasound are compared to those of transrectal laser/ultrasound. Results show that the transurethral laser has a better penetration depth in the prostate compared with transrectal one. Urethral thermal safety is investigated via COMSOL Multiphysics, and the results show that the proposed pulsed transurethral laser will cause no thermal damage on the urethral surface. Regression analysis for PA signal amplitude and drug concentration demonstrates that the PA technique has the potential to monitor drug distributions in PDT, as well as in other laser-based prostate therapy modalities.