An Annular Array System for High Resolution Breast Echography

Abstract

Ultrasound B-mode imaging with electronically focused annular arrays has been associated in the past with fairly complex and expensive electronic circuits. When image quality rather than scanning speed is the prime concern, the concept of switched zone focusing offers an attractive alternative to true dynamic focusing previously reported. Strongly focused apertures used in both transmit and receive modes allow improved lateral resolution, lower side lobe levels, higher sensitivity, as well as simplified electronics.This approach was investigated for the particular case of breast imaging. We outline some general design considerations for water path imaging with annular arrays, and describe the system adopted in the development of a high resolution breast scanner using a sealed, water filled head. Experimental results are compared to theoretical predictions, and grey scale images are presented to illustrate the performance of the instrument.

The torsional waveguide viscosity probe: Design and anomalous behavior

“…To focus the array at a depth d on transmit (or receive), the time delay t n required for ring n of the array is approximately t n = [ a n 2 (1/ R − 1/ d )]/2 c , where R is the geometric focus, c is the speed of sound, and a n is the average radius of ring n [19]. The total round-trip delays t tot = t T + t R , with t T on transmit and t R on receive, were calculated for 25 transmit-receive pairs and applied to the acquired A-lines.…”

High-Frequency Chirp Ultrasound Imaging with an Annular Array for Ophthalmologic and Small-Animal Imaging

“…To focus the array to a depth d on transmit, the time delay t n required for ring n of the array is $t_n=\left[a_n^2(1∕R-1∕d)\right]∕2c$ where R is the geometric focus and a n is the average radius of ring n (Arditi et al, 1982). The total round-trip delay, t tot , is then the sum of the transmit, t T , and receive, t R , delays; t tot = t T + t R .…”

Prospective ECG-gated mouse cardiac imaging with a 34-MHz annular array transducer

“…This approach required five transmit events at each spatial location in order to acquire all 25 transmit-to-receive M-mode data sets. Synthetic focusing consisted of applying appropriate digital delays to each transmit-to-receive pair in order to focus to an axial-depth d [23] and then summing the 25 pairs of data to form a single RF line. The process was repeated at a series of axial focal zones and the focused data from each focal zone were merged into a final composite image.…”