Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-09-03
2001-04-03
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S437000, C600S443000
Reexamination Certificate
active
06212421
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to ultrasonic detection and, more specifically, to a device for enhancing ultrasonic detection.
2. Description of the Prior Art
Currently, the most common method of diagnosing breast cancer is X-ray mammography. Although it is often effective, it uses ionizing radiation, which has an inherent risk to the tissues being examined. Ultrasound detection is also used in breast examination. Ultrasound detection is based on differences in sound velocity in normal and abnormal tissues. However, it has a low probability of detecting many non-palpable tumors. Magnetic resonance imaging has also been used, but requires sophisticated and expensive equipment.
Exposing materials such as tissues to electromagnetic radiation causes the tissues to exhibit changes in acoustic properties as a result of photonic absorption and subsequent local heating. Spectrochemical techniques such as laser-induced fluorescence have previously been used to detect malignant tumors in vivo (see, e.g., U.S. Pat. No. 5,579,773, the disclosure of which is incorporated herein by reference). Certain tissues, such as tumors, exhibit greater changes in acoustic properties than in surrounding tissues. It has also been discovered that exposing tissues to modulated or pulsed light may also cause the generation of acoustic waves in the tissue, a process often referred to as the photo-acoustic effect. In photo-acoustic detection, intensity-modulated light or pulsed light is allowed to diffuse into a specimen and photons are absorbed, inducing energy level transitions in chemical and biological compounds. When the energy levels return to their de-excited ground state, some of the energy is transformed into kinetic energy or heat. The intensity modulation of the incident radiation produces a coherent modulation of the temperature of the material that, due to thermal expansion, generates a periodic pressure fluctuation of the same frequency. This pressure fluctuation, or acoustic signal, can be detected with a microphone or transducer in contact with the material being examined.
Photo-acoustic spectroscopy has been successfully performed on a variety of biological materials (see, e.g., Rosencwaig, A.,
Photo
-
acolistics and Photo
-
acotistic Spectroscopy
, Wiley, New York, 1980). Studies of whole blood have been performed, in which conventional absorption spectroscopy has failed due to excessive light scattering. Other examples include: Photo-acoustic spectroscopy of chlorophyll within the intact green leaf and the detection of plant pathology; analysis of the biochemical characteristics of marine algae and phytoplankton and studies of the photochemical mechanisms of these organisms; the monitoring of bacteria in various stages of development; the effect of different commercial sun screens on human epidermal tissue; studies of human eye cataracts, and the detection of protein structural changes in rat epidermal tissue during postpartum maturation.
Many conventional analytical techniques (e.g., chromatography, fluorometry, spectrophotometry) are effective when applied to solutions of extracted biochemical compounds, Photo-acoustic spectroscopy has been shown to be effective in the biochemical characterization of intact and complex biological systems, such as intact cells and tissues.
SUMMARY OF THE INVENTION
This invention involves non-invasive methods and instruments for improved chemical, environmental and biomedical diagnosis using an approach based on spectro-acoustically enhanced ultrasonic detection. The combination of both ultrasonic and laser photo-acoustic methods, which is aimed at providing physical as well as spectrochemical properties of constituents of materials, will significantly extend the diagnostic applicability. This invention will greatly improve measurements of ultrasonic waves using a combination of detection approaches and probe/detector geometries. The combination of both ultrasonic and laser photo-acoustic methods will significantly extend the diagnostic efficiency and applicability for diagnosis. The basic principle of this invention is the integration of the following combination of techniques: (a) laser optical/photo-acoustic excitation, carrying the spectrochemical and electronic/ molecular properties of biological constituents of tissues; (b) ultrasonic detection containing spatial information, and the physical and mechanical properties of tissues; and (c) modulation and synchronized detection used to improve the signal-to-noise ratio of detection to achieve improved sensitivity.
The disadvantages of the prior art are overcome by the present invention which, in one aspect, is an apparatus for detecting a discontinuity in a material, in which a source of electromagnetic radiation has a wavelength and an intensity sufficient to induce an enhancement in contrast between a manifestation of an acoustic property in the material and of the acoustic property in the discontinuity, as compared to when the material is not irradiated by the electromagnetic radiation. An acoustic emitter directs acoustic waves to the discontinuity in the material. The acoustic waves have a sensitivity to the acoustic property. An acoustic receiver receives the acoustic waves generated by the acoustic emitter after the acoustic waves have interacted with the material and the discontinuity. The acoustic receiver also generates a signal representative of the acoustic waves received by the acoustic receiver. A processor, in communication with the acoustic receiver and responsive to the signal generated by the acoustic receiver, is programmed to generate informational output about the discontinuity based on the signal generated by the acoustic receiver.
In another aspect, the invention is an apparatus for detecting a mass, having a density, in a tissue, having a density. An electromagnetic radiation source directs a beam of electromagnetic radiation into the tissue toward the mass. The beam has a wavelength and intensity sufficient to induce an enhancement in contrast between the density of the mass relative to the density of the tissue. An ultrasound transmitter directs ultrasound waves into the tissue toward the mass. An ultrasound receiver receives ultrasound waves that have interacted with the tissue and the mass. A processor, responsive to the ultrasound receiver, detects the mass based on the ultrasound waves received by the ultrasound receiver.
In yet another aspect, the invention is a method of detecting a discontinuity in a material. The material is irradiated with a beam of electromagnetic radiation having an energy and an intensity sufficient to induce an enhancement in contrast between a manifestation of an acoustic property in the material and of the acoustic property in the discontinuity, as compared the contrast when the material is not irradiated by the beam. This enhanced contrast is due to the difference in the spectrochemical properties of the material and the discontinuity. The material is irradiated with acoustic waves so that acoustic energy interacts with the material and the discontinuity. Waves that have interacted with the material and the discontinuity are received. An informational output about the discontinuity based on the received waves that have interacted with the material and the discontinuity is generated.
In yet another aspect, the invention is a method of detecting a mass in a tissue. The tissue is irradiated with a beam of electromagnetic radiation having an energy and an intensity sufficient to induce an enhancement in contrast between a manifestation of an acoustic property in the tissue and of the acoustic property in the mass, as compared the contrast when the tissue is not irradiated by the beam. The tissue is also irradiated with acoustic waves so that acoustic energy interacts with the tissue and the mass. Waves that have interacted with the tissue and the mass arc received. An informational output about the mass based on the received waves that have interacted with the tissue and the mass is generated.
T
Norton Stephen J.
Vo-Dinh Tuan
Imam Ali M.
Lateef Marvin M.
Lockheed Martin Energy Research Corp.
Needle & Rosenberg P.C.
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