| Title | Code Division Multiple Element Synthetic Aperture Transmission |
| Authors | Fredrik Gran, Jörgen A. Jensen, Andreas Jakobsson |
| Full-text | Available as PDF, Restricted Access |
| Alternative Location | http://dx.doi.org/10.1117/1... |
| Publication | Proceedings of the SPIE - The International Society for Optical Engineering |
| Year | 2004 |
| Volume | 5373 |
| Issue | 1 |
| Pages | 300 - 306 |
| Document type | Conference paper |
| Conference name | Medical Imaging 2004. Ultrasonic Imaging and Signal Processing |
| Conference Date | 2004-02-14 - 19 |
| Conference Location | San Diego |
| Status | Published |
| Quality controlled | Yes |
| Language | eng |
| Publisher | SPIE-Int. Soc. Opt. Eng |
| Abstract English | In conventional synthetic transmit aperture imaging (STA) the image is built up from a number of low resolution images each originating from consecutive single element firings to yield a high resolution image. This lowers the frame rate and may result in motion artifacts. This paper, describes a method in which all transmitting centers can be excited at the same time and separated at the receiver to yield a full image in only one transmission. Hereby the benefits from traditional STA can be utilized and a high frame rate can be maintained, which thereby prevents motion artifacts. The different centers are excited using mutually orthogonal codes. The signal at the receiver is a linear combination of the transmitted signals convolved with the corresponding pulse-echo impulse response. The pulse-echo impulse responses for the different elements are modeled as finite impulse response channels and estimated using a maximum likelihood technique. The method was verified using simulations in Field II. A 7 MHz transducer was simulated with 128 receiving elements and 64 transmitting elements divided into subapertures so that 4 virtual transmission centers were formed. The point spread function was simulated and the axial resolution was 0.23 mm (-3 dB) and 0.31 mm (-6 dB). lateral resolution 0.53 mm (-3 dB) and 0.71 mm (-6 dB) and maximum lateral sidelobe level less than 44 dB. Conventional STA is given as a reference with the same aperture setup using 4 emissions excited with a single cycle sinusoid at 7 MHz. The axial resolution is here 0.23 mm (-3 dB) and 0.31 mm (-6 dB), lateral resolution 0.53 mm (-3 dB) and 0.71 mm (-6 dB) and maximum lateral sidelobe level less than 44 dB |
| Keywords | biomedical ultrasonics, convolution, image resolution, maximum likelihood estimation, medical image processing, code division technique, multiple element synthetic aperture transmission, motion artifacts, pulse-echo impulse response, finite impulse response channels, point spread function, ultrasound imaging, 7 MHz, -3 dB, -6 dB , |
| ISBN/ISSN/Other | ISSN: 0277-786X |
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