Researchers from Brown University have
found a way to use ultrasonic vibrations to take images of tumors.
The method involves using ultrasonic vibrations to image colloidal
objects, which are spherical objects like particles and blood cells that
are suspended in fluid.
The method could eventually be used for mammograms and to check
for internal bleeding, according to the researchers.
The researchers' scheme involves shooting a beam of ultrasound
through a region of the body to produce a radio frequency signal, which
the researchers process to generate a spatial representation of colloidal
The method produces a 500-fold contrast between blood and tissue,
which makes it potentially useful for imaging tumors because tumors have
more blood vessels than ordinary tissue, according to the researchers.
The fluid immediately surrounding a particle carries an electric
charge opposite the charge on the surface of the particle. This keeps
particles from clumping together. When sound waves strike colloidal objects,
they cause the fluid around the particles to oscillate. The oscillating
charge generates an alternating current, which produces radio frequency
Traditional ultrasonic imaging, in contrast, uses changes in the
speed of the sound waves caused by materials with different densities
to image different types of tissue.
The method could be ready for practical use in mammograms in two
to five years, according to the researchers. The work appeared in the
November 29, 2004 issue of Applied Physics Letters.
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