Incorporating estimated Green´s functions in microwave breast cancer imaging with DORT

The decomposition of reversed time (DORT) method is a promising algorithm for microwave breast cancer imaging. However when DORT is applied to breasts with high percentage of glandular tissues, its performance decreases due to differences in the dielectric properties of the physical and computational media. We propose a new method of deriving pair wise permittivities by using the received scattered signals in a multi antenna imaging system. We propose to use the estimated permittivities when computing the Green´s function in the backpropagation step of DORT rather than using a nominal global value. We also propose to combine multiple eigenvectors of the time reversal operator. It is observed through simulation that our enhanced DORT method achieves improved focusing accuracy in detecting the breast malignancy.