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Non-linear propagation for medical imaging

Non-linear propagation for medical imaging
Non-linear propagation for medical imaging
The propagation of high amplitude ultrasonic fields, such as those generated by some medical ultrasound systems, is not adequately described by the linear wave equation. Instead it is necessary to consider non-linear propagation if the drive levels are high enough to make non-linear effects significant. As a result of non-linear propagation the transmitted waveforms distort as they propagate, resulting in the generation of harmonics of the initial frequency components transmitted by the transducer. In the nearfield of medical transducers diffraction and focusing effects associated with the source complicate this process.
The basic physics of this non-linear propagation is reviewed and the complex characteristics of the finite amplitude fields generated by different sources are described. This is illustrated with both experimental results and numerical predictions obtained using a finite difference solution (the Bergen Code) to the Khokhlov-Zabolotskaya-Kuznetsov (or KZK) equation. The fields of both ideal sources and real medical systems are demonstrated. The use of harmonics to improve image quality is then considered, with the characteristics of the fields produced by harmonic imaging and pulse inversion systems being compared. The implications of non-linear propagation for medical ultrasound output regulation are also considered.
2 9515619 9 7
73-80
World Congress on Ultrasonics
Humphrey, V.F.
23c9bd0c-7870-428f-b0dd-5ff158d22590
Humphrey, V.F.
23c9bd0c-7870-428f-b0dd-5ff158d22590

Humphrey, V.F. (2003) Non-linear propagation for medical imaging. In Proceedings of the World Congress on Ultrasonics 2003. World Congress on Ultrasonics. pp. 73-80 .

Record type: Conference or Workshop Item (Paper)

Abstract

The propagation of high amplitude ultrasonic fields, such as those generated by some medical ultrasound systems, is not adequately described by the linear wave equation. Instead it is necessary to consider non-linear propagation if the drive levels are high enough to make non-linear effects significant. As a result of non-linear propagation the transmitted waveforms distort as they propagate, resulting in the generation of harmonics of the initial frequency components transmitted by the transducer. In the nearfield of medical transducers diffraction and focusing effects associated with the source complicate this process.
The basic physics of this non-linear propagation is reviewed and the complex characteristics of the finite amplitude fields generated by different sources are described. This is illustrated with both experimental results and numerical predictions obtained using a finite difference solution (the Bergen Code) to the Khokhlov-Zabolotskaya-Kuznetsov (or KZK) equation. The fields of both ideal sources and real medical systems are demonstrated. The use of harmonics to improve image quality is then considered, with the characteristics of the fields produced by harmonic imaging and pulse inversion systems being compared. The implications of non-linear propagation for medical ultrasound output regulation are also considered.

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More information

Published date: 2003
Additional Information: CD-ROM
Venue - Dates: Proceedings of the World Congress on Ultrasonics 2003, Paris, France, 2003-09-06 - 2003-09-09

Identifiers

Local EPrints ID: 10343
URI: http://eprints.soton.ac.uk/id/eprint/10343
ISBN: 2 9515619 9 7
PURE UUID: c2c725fe-4c67-4837-b2a2-1932cf892453
ORCID for V.F. Humphrey: ORCID iD orcid.org/0000-0002-3580-5373

Catalogue record

Date deposited: 01 Jul 2005
Last modified: 12 Dec 2021 03:24

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