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Effects of Acoustic Heterogeneity in X-Ray-Induced Acoustic Computed Tomography

C Cochran1*, P Samant2 , L Xiang3 , (1) University of Oklahoma, Norman, OK, (2) University of Oklahoma, Norman, OK, (3) University of Oklahoma, Norman, OK


(Sunday, 7/14/2019) 3:00 PM - 3:30 PM

Room: Exhibit Hall | Forum 4

Purpose: X-ray-induced acoustic computed tomography (XACT) is a promising imaging modality combining high x-ray absorption contrast with the 3D propagation advantages provided by high resolution ultrasound waves. XACT imaging as a novel biomedical imaging modality has great potential in biomedical imaging and radiation therapy monitoring. However, XACT imaging is skewed by acoustic heterogeneities, and by assuming an incorrect speed of sound. Incorrect speed of sound settings and acoustic heterogeneities dilate and deform ultrasound images, respectively.

Methods: k-Wave is a MATLAB toolbox designed for the time-domain simulation of acoustic wave propagation and is used in this study. Firstly, a grayscale CT image is segmented into different tissue types where the tissue is assigned a speed of sound, attenuation coefficient, and density at each pixel. Based off these values, acoustic wave propagation through the tissue is simulated and reconstructed using the time reversal algorithm.

Results: Reconstructed image quality is affected by the constant or variable assignment of the attenuation coefficient, speed of sound and density. The reconstructed image resolution increases as these variables are defined at each pixel, however the images also have more noise.

Conclusion: Speed of sound errors dilate and acoustic heterogeneities deform XACT images. The reconstructed image resolution increases when simulated with heterogenous media but are also noisier than the simulations with homogenous media. The correct assignment of media properties is useful in increasing the resolution of reconstructed images.


Anisotropy, K-space, Reconstruction


IM- Ultrasound : Image Reconstruction

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