Effect of the illumination method on photo-acoustic image quality with array transducer based system

Abstract

Photo-acoustic imaging (PAI) is a hybrid imaging modality, which can offer a high contrast tomographic image with ultrasound like resolution in depth of centimeters. Additionally, it has been studied well as functional imaging modality using characteristics that can distinguish by absorption spectra. Our purpose is to investigate the image quality and potential of photo-acoustic (PA) image as a preliminary study toward the medical diagnosis applications. For this purpose, firstly we focused on the difference of image quality between photo-acoustic image and ultrasound image using array transducers system. Secondly we examined the effect of illumination method on photo-acoustic image quality. We compared both photo-acoustic image and ultrasound image of a phantom using original PAI experimental apparatus system with 192ch PZT array probe. Resolution of PAI and ultrasound image could be revealed, based on the optimized reconstruction method for each using each element data. We demonstrated higher resolution and higher contrast of photo-acoustic image than ultrasound image. To examine the effect on photo-acoustic image quality, we analyzed depth-dependent signal attenuation in scattering media under various illumination methods such as the expansion of illumination area. Our analysis with experiments and Monte Carlo simulation are performed to show the necessity for illumination optimization depend on the application and probe size.