Feasibility Study of Acoustic Imaging for Human Thorax Using Contrast Source Inversion

In this paper, we study an acoustic imaging method based on contrast source inversion and its feasibility in quantitatively reconstructing the thorax compressibility and qualitatively reconstructing the thorax attenuation and density. The existence of gradient and divergence operator in the acoustic wave equation makes the relationship between the contrast and the total pressure highly nonlinear. To reduce this nonlinearity, we introduce two contrast sources to ensure the symmetry of the equation, such that the inverse problem can be solved efficiently using conjugate gradient method. Moreover, to improve the stability of the algorithm, we applied the multiplicative regularization scheme with two additive regularization factors. Numerical results show that the acoustic parameters of human thorax can be properly reconstructed at frequency of tens of kHz using this inverse algorithm.