Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-12-07
2001-06-12
Manuel, George (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
Reexamination Certificate
active
06245015
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to systems for imaging human tissue using both ultrasound and light waves and, more particularly, to systems for imaging the interior of a highly scattering medium such as the human breast in a non-invasive manner using ultrasound to generate modulated optical intensity waves (diffusion waves).
BACKGROUND OF THE INVENTION
Visible and near-infrared light tomography has been used to image the interior of tissue media. Diffusion wave tomography has also been used to image tissue. Visible and near-infrared light tomography is limited to relatively small depths of penetration, e.g., on the order of a few millimeters in breast tissue, whereas diffusion wave tomography has relatively poor resolution, e.g., on the order of a centimeter in breast tissue. It would be an advance in the state of the art if a system were developed to overcome the foregoing disadvantages of the prior art. In particular, it would be highly desirable to use visible and near-infrared light to image inhomogeneities, such as tumors, in the interior of the human breast non-invasively with a high degree of spatial resolution.
SUMMARY OF THE INVENTION
A system which generates optical diffusion waves inside a localized region in a highly scattering medium such as human breast tissue by simultaneously using visible and near-infrared light and focusing ultrasound waves in localized regions of the breast. The sources of visible and near-infrared light each comprise at least one laser. The vibrating tissue medium scatters the light impinging thereon to produce intensity-modulated diffusion waves. The diffusion waves emanating from the insonified region have a frequency equal to the frequency of the ultrasound waves (or a harmonic thereof). The resulting diffusion waves are detected at the boundary of the breast and are processed to acquire data on the absorption and scattering parameters of the insonified region. In accordance with one preferred embodiment, one or more diffusion wave detectors are arranged at the boundary of the breast to detect scattered diffusion waves at respective locations. Each diffusion wave detector comprises an optical-to-electrical transducer, i.e., a photodetector, such as a photomultiplier tube or a photodiode. The output signal of each diffusion wave detector is in turn fed to a detector which detects the amplitude and phase of the diffusion waves. Then the amplitude and phase signal components are fed to a processor which computes pixel values for display on a monitor.
The amplitude and phase of the scattered diffusion waves are proportional to the density/composition of the insonified region. Thus, by scanning different regions within the tissue by ultrasound and recording the amplitude and phase of the scattered diffusion waves, it is possible to map out the density and composition of the interior of the highly scattering breast tissue. From the spectroscopic characteristics of these parameters at selected wavelengths in the visible and near-infrared (500 to 1,400 nm), the localized regions inside the breast can be classified as cancerous or benign tumors or healthy breast tissue.
REFERENCES:
X.D. Li, T. Durduran, B. Chance, A.G. Yodh, D.N. Pattanayak, “Diffraction Tomography For Biomedical Imaging With DiffusePhoton Density Waves”, SPIE Conference Society for Photo Illuminescent Engineering, 2/97.
General Electric Company
Ingraham Donald S.
Manuel George
Stoner Douglas E.
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