Photoacoustic image reconstruction Zhou, Kevin; Zhang, Zongyi; Yang, Sean
Our project’s main objective is to design and improve an accurate, reliable image reconstruction algorithm using the Delay and Sum method. The Fast Fourier Transform algorithm is also investigated to evaluate the efficiency and performance of our choice of algorithm. The developed MATLAB programs are to be able to take in the pre-beam-formed data acquired by the ultrasound system and reconstruct proper images of the planned seeds in the phantom. The developed algorithms should work to produce images with a satisfactory resolution for both homogeneous and inhomogeneous materials. Photoacoustic imaging is a fairly modern technique in the medical imaging filed, and it’s under rapid development. While the principle of photoacoustic effect and ultrasound wave production has been discovered more than a century ago, its potential application as a medical tool has really only come into development after the common use of ultrasound imaging and the availability of advanced ultrasound transducers. Our algorithms aim to reconstruct images using acquired data with a satisfactory resolution. Speed is also one consideration, as the algorithms have the potential to be integrated into a future system to achieve real-time imaging. Clarity of reconstruction judged from a qualitative standpoint, numerical analysis of signal to noise ratio (SNR), and some considerations of computation time were discussed in this document. Simulated data and experimental data, generated using phantoms constructed of metal seeds, were both used in analyzing the performance of our algorithms. Our findings suggest that while the computation time for both algorithms under identical situations is reasonably short for practical use, the FFT algorithm that we developed has shown significant SNR performance advantage over the Delay and Sum algorithm for homogeneous medium, indicating higher image quality. However, the FFT algorithm cannot reconstruct images using data obtained with inhomogeneous medium. Therefore, the Delay and Sum algorithm is a more viable image reconstruction algorithm to be used in various practical cases with medium not limited to homogenous materials.
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