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Proceedings Paper

Should compression of coded waveforms be done before or after focusing?
Author(s): Rasmus Bjerngaard; Joergen Arendt Jensen
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Paper Abstract

In medical ultrasound signal-to-noise ratio improvements of approximately 15-20 dB can be achieved by using coded waveforms. Exciting the transducer with an encoded waveform necessitates compression of the response which is computationally demanding. This paper investigates the possibility of reducing the workload without introducing errors. Ne - 1 compression filtrations (convolutions) can be saved by inverting the precedence of compression and beamforming (called post-compression), when N is the number of transducer elements. Post-compression with dynamic receive focusing will theoretically introduce errors. Simulations and measurements show that increasing the depth of the scatterers results in a decreased error. Transmit focus depth and the distance between focus points have a significant influence on the error. The size of the error is studied and a new scheme for correcting the error is proposed. The study is done by simulations in Field II and by measurements with our experimental scanner RASMUS. The measurements are done on a string phantom and in-vivo on the abdomen of a male volunteer.

Paper Details

Date Published: 11 April 2002
PDF: 12 pages
Proc. SPIE 4687, Medical Imaging 2002: Ultrasonic Imaging and Signal Processing, (11 April 2002); doi: 10.1117/12.462176
Show Author Affiliations
Rasmus Bjerngaard, B-K Medical and Technical Univ. of Denmark (Denmark)
Joergen Arendt Jensen, Technical Univ. of Denmark (Denmark)

Published in SPIE Proceedings Vol. 4687:
Medical Imaging 2002: Ultrasonic Imaging and Signal Processing
Michael F. Insana; William F. Walker, Editor(s)

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