Portal de Periódicos da CAPES

<title>Multi-element synthetic transmit aperture imaging using temporal encoding</title>

2002; SPIE; Volume: 4687; Linguagem: Inglês

10.1117/12.462168

1996-756X

K.L. Gammelmark, Jørgen Arendt Jensen,

Ultrasonics and Acoustic Wave Propagation

A new method to increase the signal-to-noise-ratio (SNR) of synthetic transmit aperture (STA) imaging is investigated. The new approach is called temporally Encoded Multi-Element STA imaging (EMESTA). It utilizes multiple elements to emulate a single transmit element, and the conventional short excitation pulses are replaced by linear FM signals. Simulations using Field II and measurements are compared to linear array imaging. A theoretical analysis shows a possible improvement in SNR of 17 dB. Simulations are done using an 8.5 MHz linear array transducer with 128 elements. Spatial resolution results show better performance for EMESTA imaging after the linear array focus. Both methods have similar contrast performance. Measurements are performed using our experimental multi-channel ultrasound scanning system, RASMUS. The designed linear FM signal obtains temporal sidelobes below -55 dB, and SNR investigations show improvements of 4-12 dB. The depth performance is investigated using a multi-target phantom. Results show a 30 mm increase in penetration depth with improved spatial resolution. In conclusion, EMESTA imaging significantly increases the SNR of STA imaging, exceeding that of linear array imaging.