An improved extrapolation method and its application in ultrasound computerized tomography

In ultrasound computer tomography, according to Fourier diffraction theorem, when an object illuminated with an ultrasound wave, the Fourier transform of the forward scatter field gives values of 2-D transform of the object along semicircular arcs in the frequency domain.We can reconstruct the object with data sampled from these arcs. However, these values are all limited in a low frequency band.Aiming this problem, a new extrapolation scheme was proposed in this paper. Papoulis-Gerchberg (G-P) algorithm is first applied, using spatial constraint information iterative to get the initial information in high frequency, then an improved method of nonlinear extrapolation is applied to enhance the high frequency part. The simulation results show the new method largely improves reconstruction quality.