Recovery of photoacoustic images based on accurate ultrasound positioning

Abstract

Photoacoustic microscopy is an in vivo imaging technology based on the photoacoustic effect. It is widely used in various biomedical studies because it can provide high-resolution images while being label-free, safe, and harmless to biological tissue. Polygon-scanning is an effective scanning method in photoacoustic microscopy that can realize fast imaging of biological tissue with a large field of view. However, in polygon-scanning, fluctuations of the rotating motor speed and the geometric error of the rotating mirror cause image distortions, which seriously affect the photoacoustic-microscopy imaging quality. To improve the image quality of photoacoustic microscopy using polygon-scanning, an image correction method is proposed based on accurate ultrasound positioning. In this method, the photoacoustic and ultrasound imaging data of the sample are simultaneously obtained, and the angle information of each mirror used in the polygon-scanning is extracted from the ultrasonic data to correct the photoacoustic images. Experimental results show that the proposed method can significantly reduce image distortions in photoacoustic microscopy, with the image dislocation offset decreasing from 24.774 to 10.365 μm.

Restoring the imaging quality of circular transducer array-based PACT using synthetic aperture focusing technique integrated with 2nd-derivative-based back projection scheme

“…By converting optical energy into acoustic energy, which is 2–3 orders of magnitude less scattered than photons, PA imaging breaks the optical diffusion limit (1 mm in biological tissue) and significantly extends the imaging depth to ranges that are inaccessible by conventional optical imaging. Generally, PA imaging is classified into two major implementations: scanning-based photoacoustic microscopy (PAM) [5] , [6] and reconstruction-based photoacoustic computed tomography (PACT) [7] , [8] . Transducer arrays with multiple elements are typically used for PA signal detection in PACT, which significantly enhances the imaging speed compared with a single-element transducer that requires point-by-point scanning in the case of PAM.…”