Image reconstruction algorithm for laser-induced ultrasonic imaging: The single sensor scanning synthetic aperture focusing technique

Abstract

This paper aims to implement a laser-induced ultrasound imaging reconstruction method based on the delay-and-sum beamforming through the synthetic aperture focusing technique (SAFT) for a circular scanning, performed with a tomograph that had one acoustic sensor and a system that rotates the sample around a fixed axis. The proposed method, called the Single-sensor Scanning Synthetic Aperture Focusing Technique, considers the size of the sensor and the detection procedure inside the SAFT's algebra. This image reconstruction method was evaluated numerically, using the Green function for the laser-induced ultrasound wave equation to generate a forward problem, and experimentally, using a solid object of polylactic acid, and a Sprague–Dawley rat heart located in a tissue-mimicking phantom. The resulting images were compared to those obtained from the time reversal and the conventional delay-and-sum reconstruction algorithms. The presented method removes the sidelobe artifacts and the comet tail sign, which produces a more distinguishable target on the image. In addition, the proposed method has a faster performance and lower computational load. The implementation of this method in photoacoustic microscopy techniques for image reconstruction is discussed.

Advanced Image Post-Processing Methods for Photoacoustic Tomography: A Review

“…Currently, common PAT image reconstruction algorithms include delay and sum (DAS) [6,19], back projection (BP) [20], and model-based (MB) [21,22] methods. Under ideal conditions, no additional processing steps are required for image reconstruction.…”

“…Specifically, as shown in Figure 1b, image reconstruction involves turning the raw signal into a desired image, while image post-processing entails enhancing and optimizing the reconstructed images. While a majority of previous research in PAT imaging was dedicated to image reconstruction [6], there has been a recent surge in studies focused on PAT image post-processing methods. As researchers delve deeper into the potential of the image post-processing technique, it is becoming increasingly evident that it plays a crucial role in enhancing the accuracy and reliability of PAT.…”