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CenSSIS: Acoustics Group at Boston University
Medical Ultrasound Testbed (MedBED)
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Overview
The MedBED facility at BU consists of experimental facilities to carry out general
ultrasound imaging. MedBED provides a controlled environment by which to take data
for the following applications:
forward propagation, tomography, complex tissue mimicking media, dual wave modalities,
and nonlinear imaging. The facility has three instrumented tanks, access to 2 wet labs
(including a biohazard lab) and facilities for tissue phantom development and characterization
Large Ultrasound Test Facility (LUTF)
The Large Ultrasound Test Facility (LUTF) is the largest of the MedBED test tanks. It is
2 m long by 1 m wide and 1 m high and can support experiments at acoustic frequencies
ranging from about 200 kHz up to about 30 MHz. The tank has optical access
on 5 sides and sufficient working space to permit multi-modal sensing and imaging experiments.
It is presently equipped with 4-axis (3 translation and 1 rotation)
computer-controlled positioning system allows access to the complete tank with positioning
accuracy of 25 µm. A second manual 2-axis
(rotation and depth) positioning system is also available. Data is acquired via a high-speed
capture board sitting on a computer bus or a digital scopes. All experimental control and
data acquistion is done using the data acquisition toolbox provided with Matlab
(The Mathworks is a CenSSIS partner). This includes a
high-level package that allows a user to characterize the acoustic field of a transducer.
Analogic Ultrasound Engine
The Analogic Ultrasound Engine (AN 2300) is the flagship data
acquisition platform for MedBED. It is the underlying hardware for the B-K Medical
Viking 2400 scanner
The AN2300 can operate B-mode scanheads with up to 192 elements. It has a fully digital
transmit and receive beamforming which can address upto 64 elements
from the scanhead in a given pulse-echo A-line. The system is controlled through
open-source software which allows complete access to the internal signals and
controls within the imager.
In collaboration with the Mathworks we have developed a Matlab interface which
allows us to access the raw beamformed RF data from Matlab.
Scanning Acousic Microscope
The scanning acoustic microscope (SAM) employs a much smaller tank and works
for frequencies ranging from 20MHz to 200MHz. Currently it uses a 75 MHz ultrasound
transducer, with the focal length of 12.7 mm. The transducer can be translated in
two-dimensions with a motorized positioning stage that has less than 1 µm accuracy.
There is a 2-axis micro-positioning stage for placement of the target.
The transducer is excited by a pulser-receiver and the echo signals are recorded
with a digital oscilloscope and transferred to computer. The system is under
computer control through Matlab. An analysis technique has been developed to
determine the impedance, sound-speed and attenuation of an unknown sample based on
the reflections from the front and back surface of the sample.
Dual Wave Facility
The dual wave facility consists of an optical table and small tank for doing experiments
which use a combination of light and sound.
Example data set
Phanton 8 Oct 01 Preliminary
ultrasound scans using a single element transducet to interrogate a tissue phantom.
Department of Aerospace and
Mechanical Engineering
110 Cummington Street
Boston University
Boston, Massachusetts 02215
Last Updated Jan 2003
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