Optimization of image quality in photoacoustic tomography using spatial projection data

Abstract

The use of camera based optical ultrasound detection that records snapshot projections of the acoustic field can provide three-dimensional (3D) photoacoustic images with uniform spatial resolution. However, this is only the case if two conditions are satisfied. First, the detection angle that is covered by the acoustic field within the field of view (FOV) of the camera should be as large as possible, ideally approaching 180° in order to avoid limited view artifacts. Secondly, the extension of the region of interest (ROI) along projection direction needs to be smaller than the depth of field of the optical system for ultrasound detection. From the recorded wave pattern snapshots, photoacoustic projection images are reconstructed using a back propagation Fourier domain reconstruction algorithm. Applying the inverse Radon transform to a set of 200 projections recorded over a half rotation of the sample provides 3D photoacoustic tomography images. In this work we investigate an acoustic cavity approach to increase the detection angle, thereby reducing limited view effects due to missing information in lateral direction. The performance of the method to improve the final 3D photoacoustic image quality is investigated on a numerical phantom sample and first experimental 2D imaging results are shown.