Abstract
In this paper a method for spatio-temporal encoding is presented for synthetic transmit aperture ultrasound
imaging (STA). The purpose is to excite several transmitters at the same time in order to transmit more
acoustic energy in every single transmission. When increasing the transmitted acoustic energy, the signal to
noise ratio will increase. However, to focus the data properly using the STA approach, the transmitters have to
be separated from each other. This is done by dividing the available spectrum into several subbands with a small
overlap. Separating different transmitters can be done by bandpass filtering. Therefore, the separation can be
done instantaneously without the need for further transmissions, unlike spatial encoding relying on Hadamard
or Golay coding schemes, where several transmissions have to be made before the decoding can be done. Motion
artifacts from the decoding can, thus, be avoided. To further increase the transmitted energy, the excitation
waveforms are designed as linear frequency modulated (FM) signals. This makes it possible to maintain the full
excitation amplitude during most of the transmission. The design of the separation filters will also be discussed.
The method was tested using the experimental ultrasound scanner RASMUS and evaluated using a reference
setup with a linear FM excitation waveform and STA beamforming. The point spread function (PSF) was
measured on a wire phantom in water. A wire phantom with an attenuating medium was also measured, where
the proposed method achieved approximately 2 cm improvement in penetration depth. The signal to noise ratio
was also measured, where the gain was
∼ 7 dB in comparison to the reference.
Original language | English |
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Title of host publication | Proceedings of SPIE Medical Imaging meeting : Ultrasonic Imaging and Signal Processing |
Volume | 5750 |
Publisher | SPIE - International Society for Optical Engineering |
Publication date | 2005 |
Pages | 405-416 |
DOIs | |
Publication status | Published - 2005 |
Event | SPIE Medical Imaging 2005 - San Diego, United States Duration: 12 Feb 2005 → 17 Feb 2005 |
Conference
Conference | SPIE Medical Imaging 2005 |
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Country/Territory | United States |
City | San Diego |
Period | 12/02/2005 → 17/02/2005 |
Keywords
- Spatial and temporal encoding
- Coded ultrasound imaging
- Synthetic transmit aperture ultrasound