title: Synchronous dynamic focusing for ultrasound imaging.
abstract: An approach to dynamic focusing of ultrasound linear array scanners is presented, leading to the unique capability of implementing a focus that continuously tracks the return signal along the penetration depth. An electronically variable lens is obtained by a heterodyning process, in which the phases of echo signals at the array elements are equalized by mixing with suitable reference oscillations. These are generated by control of a single voltage-controlled oscillator, whose frequency is properly varied in synchronism with the delay of signal from different depths. The technique has been experimentally demonstrated by modifying the focusing processor of a conventional echographic linear scanner. Superior performances have been obtained with respect to fixed-focus operation mode. The image quality results are comparable with those of multizone-focus operation mode, in which the focus is varied over more transmit/receive cycles at the expense of lower frame rate.
authors.affiliation: Dept. of Electron. Eng., Florence Univ.
authors.forename: G
authors.initials: G
authors.lastname: Manes
authors.forename: P
authors.initials: P
authors.lastname: Tortoli
authors.forename: F
authors.initials: F
authors.lastname: Andreuccetti
authors.forename: G
authors.initials: G
authors.lastname: Avitabile
authors.forename: C
authors.initials: C
authors.lastname: Atzeni