Radiation-induced thermoacoustic imaging
First Claim
1. A method of radiation-induced thermoacoustic imaging to non-invasively detect the composition and structure of a body, comprising the steps ofinducing within a volume under investigation in said body a sudden thermal stress by a pulse of radiation which deposits energy causing a rapid, but very small, rise in temperature throughout said volume, andreceiving the thermoacoustic signal emitted from within said volume as a result of the induced sudden thermal stress, thereby producing an image of inhomogenieties within said volume.
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Abstract
The acoustic wave generated by sudden thermal stress is used to obtain information non-invasively on the composition and structure of the stressed body. One or more acoustic transducers (1 and 1'"'"') are coupled with the surface of the body to intercept the acoustic wave and generate a corresponding electrical signal. The sudden thermal stress is induced by a pulse of radiation which deposits energy causing a rapid, but very small, rise of temperature. The radiation may be ionizing radiation, such as high energy electrons, photons (X-rays), neutrons, or other charged particles. The radiation may also be non-ionizing radiation, such as RF(2) and microwave electromagnetic radiation (3) and ultrasonic radiation (4). The electrical signal from the acoustic transducer (1) is amplified (5) and supplied to a digitizer (6), which provides a continuous stream of digital words corresponding to samples of the amplified signal. Because in most situations of practical interest the S/N ratio of a single pulse is much less than unity, it is necessary to signal-average the signals from many successive pulses. This is accomplished with a minicomputer or data processor ( 8) suitably interfaced (7) with the digitizer. The resulting data can then be suitably displayed as an image on a CRT display (9) or plotted or numerically printed out.
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Citations
27 Claims
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1. A method of radiation-induced thermoacoustic imaging to non-invasively detect the composition and structure of a body, comprising the steps of
inducing within a volume under investigation in said body a sudden thermal stress by a pulse of radiation which deposits energy causing a rapid, but very small, rise in temperature throughout said volume, and receiving the thermoacoustic signal emitted from within said volume as a result of the induced sudden thermal stress, thereby producing an image of inhomogenieties within said volume.
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6. A method of non-invasive thermoacoustic imaging of soft-tissue regions in humans and animals, comprising the steps of
coupling at least one acoustic transducer with the surface of a region to be investigated, inducing within said region sudden thermal stresses by a series of pulses of radiation which deposit energy causing rapid, but very small, rises in temperature throughout said region, receiving the thermoacoustic signals emitted from within said region as a result of the induced thermal stresses, and signal-averaging the received signals produced as a result of the induced sudden thermal stresses, thereby producing an image of inhomogenieties within said region.
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10. Apparatus for non-invasively detecting the composition and structure of a body by radiation-induced thermoacoustic imaging, comprising:
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means for inducing within a volume under investigation in said body a sudden thermal stress by a pulse of radiation which deposits energy causing a rapid, but very small, rise in temperature throughout said volume, and means for receiving the thermoacoustic signal emitted from within said volume as a result of the induced sudden thermal stress, thereby producing an image of inhomogenieties within said volume. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. Apparatus for non-invasively imaging soft-tissue regions in humans and animals by means of thermoacoustic imaging, comprising:
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at least one acoustic transducer coupled with the surface of a region to be investigated, means for inducing within said region sudden thermal stresses by a series of pulses of radiation which deposit energy causing rapid, but very small, rises in temperature throughout said region, means for receiving the thermoacoustic signals emitted from within said region as a result of the induced thermal stresses, and means for signal-averaging the received signals produced as a result of the induced sudden thermal stresses, thereby producing an image of inhomogenieties within said region. - View Dependent Claims (25, 26, 27)
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Specification