Use of the Total Focusing Method with the Envelope Feature

Abstract

This paper presents how to compute the envelope of a total focusing method (TFM) image and the benefits of using this TFM envelope as part of a code-compliant solution. The TFM envelope is obtained by computing the norm of two different TFM images; namely, a first TFM image computed using the standard acquired full matrix capture (FMC), and a second TFM image computed using the Hilbert-transformed FMC. The resulting TFM envelope image provides a better basis for the amplitude-based sizing technique, as it is more robust to amplitude variation compared with a standard oscillatory TFM image at an identical grid resolution. Therefore, with respect to the standard oscillatory TFM, a coarser grid resolution can be set for the TFM envelope, consequently reducing the total amount of computation effort and ultimately increasing the resulting acquisition rate.