3D synthetic aperture imaging using a virtual source element in the elevation plane

Svetoslav Nikolov, Jørgen Arendt Jensen

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Abstract

The conventional scanning techniques are not directly extendable for 3D real-time imaging because of the time necessary to acquire one volume. Using a linear array and synthetic transmit aperture, the volume can be scanned plane by plane. Up to 1000 planes per second can be scanned for a typical scan depth of 15 cm and speed of sound of 1540 m/s. Only 70 to 90 planes must be acquired per volume, making this method suitable for real-time 3D imaging without compromising the image quality. The resolution in the azimuthal plane has the quality of a dynamically focused image in transmit and receive. However, the resolution in the elevation plane is determined by the fixed mechanical elevation focus. This paper suggests to post-focus the RF lines from several adjacent planes in the elevation direction using the elevation focal point of the transducer as a virtual source element, in order to obtain dynamic focusing in the elevation plane. A 0.1 mm point scatterer was mounted in an agar block and scanned in a water bath. The transducer is a 64 elements linear array with a pitch of 209 μm. The transducer height is 4 mm in the elevation plane and it is focused at 20 mm giving a F-number of 5. The point scatterer was positioned 96 mm from the transducer surface. The transducer was translated in the elevation direction from -13 to +13 mm over the scatterer at steps of 0.375 mm. Each of the 70 planes is scanned using synthetic transmit aperture with 8 emissions. The beam-formed RF lines from the planes are passed through a second beamformer, in which the fixed focal points in the elevation plane are treated as virtual sources of spherical waves. Synthetic aperture focusing is applied on them. The -6 dB resolution in the elevation plane is increased from 7 mm to 2 mm. This gives a uniform point spread function, since the resolution in the azimuthal plane is also 2 mm.
Original languageEnglish
Title of host publicationProceedings of IEEE Ultrasonics Symposium
Volume2
Place of PublicationSan Juan
PublisherIEEE
Publication date2000
Pages1743-1747
ISBN (Print)0-7803-6365-5
DOIs
Publication statusPublished - 2000
Event2000 IEEE Ultrasonics Symposium - San Juan, Puerto Rico
Duration: 22 Oct 200025 Oct 2000
http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=7345

Conference

Conference2000 IEEE Ultrasonics Symposium
CountryPuerto Rico
CitySan Juan
Period22/10/200025/10/2000
Internet address

Bibliographical note

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