Blood flow measurement system
First Claim
1. A blood flow measurement system for measuring blood flow rate and blood flow velocity comprising:
- means for irradiating a in vivo tissue measurement subject with coherent light;
means for receiving scattered light from the in vivo tissue;
means for converting an intensity of the received scattered light into an electrical signal;
means for calculating a power spectrum of the time-course variation of the scattered light intensity based on the electrical signal;
means for plotting the power spectrum in a semilogarithmic coordinate system having a logarithmic vertical axis;
means for linearly approximating a prescribed frequency component of the semilogarithmic power spectrum and calculating a slope and a y intercept of the power spectrum curve; and
means for calculating blood flow velocity from the slope of the curve approximating the power spectrum and calculating the blood flow rate from the slope and y intercept of the curve approximating the power spectrum.
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Accused Products
Abstract
A blood flow measurement system for measuring blood flow rate and blood flow velocity comprises a circuit device for irradiating an in vivo tissue measurement subject with coherent light, a light receiving element for receiving scattered light from the in vivo tissue, a converter for converting an intensity of the received scattered light into an electric signal, a circuit device for calculating a power spectrum of the time-course variation of the scattered light intensity, a device for plotting the power spectrum in a semilogarithmic coordinate system having a logarithmic vertical axis, and a device for linearly approximating a prescribed frequency component of the semilogarithmic power spectrum and calculating a slope and a y intercept of the power spectrum curve. The blood flow velocity can be determined from the slope of the curve approximating the power spectrum, while blood flow rate can be determined from the slope and y intercept of the curve approximating the power spectrum.
89 Citations
21 Claims
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1. A blood flow measurement system for measuring blood flow rate and blood flow velocity comprising:
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means for irradiating a in vivo tissue measurement subject with coherent light; means for receiving scattered light from the in vivo tissue; means for converting an intensity of the received scattered light into an electrical signal; means for calculating a power spectrum of the time-course variation of the scattered light intensity based on the electrical signal; means for plotting the power spectrum in a semilogarithmic coordinate system having a logarithmic vertical axis; means for linearly approximating a prescribed frequency component of the semilogarithmic power spectrum and calculating a slope and a y intercept of the power spectrum curve; and means for calculating blood flow velocity from the slope of the curve approximating the power spectrum and calculating the blood flow rate from the slope and y intercept of the curve approximating the power spectrum. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A blood flow measurement system for measuring blood flow rate and blood flow velocity comprising:
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means for irradiating an in vivo tissue measurement subject with coherent light; means for receiving scattered light from the in vivo tissue; means for converting an intensity of the received scattered light into an electrical signal; first calculating means for calculating a power spectrum of the time-course variation of the scattered light intensity based on the electrical signal; means for exponentially approximating frequency components of the power spectrum above several hundred Hz and calculating a 1/e width and a DC intensity of the power spectrum; and second calculating means for calculating the blood flow velocity from the 1/e width of the power spectrum and calculating the blood flow rate from the 1/e width and the DC intensity obtained by exponential approximation of the power spectrum. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A blood flow measurement system comprising:
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means for irradiating a single blood vessel with coherent light of at least two wavelengths; means for receiving scattered light of each wavelength from erythrocytes in the blood vessel; at least one measurement probe having means for maintaining the diameter of the blood vessel constant; means for photoelectrically converting the scattered light of each wavelength from the erythrocytes into a scattered light intensity variation electrical signal; means for calculating a power spectrum of the scattered light intensity variation electrical signal by Fourier transform; means for plotting a semilogarithmic power spectrum whose vertical axis is scaled logarithmically and whose frequency axis is scaled arithmetically; means for linearly approximating a component of the power spectrum above several hundred Hz and calculating the slope and y intercept of the approximated power spectrum curve; and means for calculating blood flow velocity from the slope of the curve approximating the power spectrum, calculating blood flow rate from the blood flow velocity and a sectional area of the blood vessel determined from the constant blood vessel diameter maintained by the measurement probe, and calculating the degree of oxygen saturation by calculating an absorption degree for each wavelength by comparing integrated intensities calculated from the product of the slopes and the y intercepts of the power spectrums at the two wavelengths.
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Specification