title: Depth-of-field enhancement in Filtered-Delay Multiply and Sum beamformed images using Synthetic Aperture Focusing.
abstract: The Synthetic Aperture Focusing (SAF) technique makes it possible to achieve a higher and more uniform quality of ultrasound images throughout depth, as if both transmit and receive dynamic focusing were applied. In this work we combine a particular implementation of SAF, called Synthetic Transmit Aperture (STA) technique, in which a single element in turn transmits and all the array elements receive the ultrasound wave, with the Filtered-Delay Multiply and Sum (F-DMAS) non-linear beamforming algorithm that we presented in a previous paper. We show that using F-DMAS, which is based on a measure of backscattered signal spatial correlation, B-mode images have a higher contrast resolution but suffer from a loss of brightness away from the transmit focus, when a classical scan with receive-only dynamic focusing is performed. On the other hand, when synthetic transmit focusing is achieved by implementing STA, such a loss is compensated for and a higher depth of field is obtained, as signal coherence improves. A drawback of SAF/STA however is the reduced signal-to-noise ratio, due to single-element transmission; in the paper we also analyze how this influences F-DMAS images. Finally, a preliminary investigation on the use of the classical monostatic SAF technique with F-DMAS beamforming is also carried out to evaluate its potential performances.
authors.affiliation: Dipartimento di Ingegneria Industriale e dell'Informazione, Università degli Studi di Pavia, Pavia, Italy. Electronic address: giulia.matrone@unipv.it.
authors.forename: Giulia
authors.initials: G
authors.lastname: Matrone
authors.affiliation: Dipartimento di Ingegneria, Università degli Studi Roma Tre, Rome, Italy.
authors.forename: Alessandro Stuart
authors.initials: AS
authors.lastname: Savoia
authors.affiliation: Dipartimento di Ingegneria, Università degli Studi Roma Tre, Rome, Italy.
authors.forename: Giosuè
authors.initials: G
authors.lastname: Caliano
authors.affiliation: Dipartimento di Ingegneria Industriale e dell'Informazione, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Magenes
keywords: Beamforming; Filtered-Delay Multiply and Sum; Synthetic Aperture Focusing; Ultrasound medical imaging