  Ultrasound computed tomography (USCT) holds great promise for improving the
detection and management of breast cancer. Because they are based on the
acoustic wave equation, waveform inversion-based reconstruction methods can
produce images that possess improved spatial resolution properties over those
produced by ray-based methods. However, waveform inversion methods are
computationally demanding and have not been applied widely in USCT breast
imaging. In this work, source encoding concepts are employed to develop an
accelerated USCT reconstruction method that circumvents the large computational
burden of conventional waveform inversion methods. This method, referred to as
the waveform inversion with source encoding (WISE) method, encodes the
measurement data using a random encoding vector and determines an estimate of
the sound speed distribution by solving a stochastic optimization problem by
use of a stochastic gradient descent algorithm. Both computer-simulation and
experimental phantom studies are conducted to demonstrate the use of the WISE
method. The results suggest that the WISE method maintains the high spatial
resolution of waveform inversion methods while significantly reducing the
computational burden.
