US4109647A
Expired / Lapsed
US
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Method of and apparatus for measurement of blood flow using coherent light
Assignee: United States Department of Health and Human Services
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Filing: 1977-03-16
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Granted: 1978-08-29
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Expires: 1997-03-16
Abstract
Abstract An apparatus for measuring the flow parameter of blood flowing in an organ includes a laser and associated optics which effect the illumination of tissues. The laser light, scattered by the tissues, emerges with a spectrum broadened by Doppler effect due to motion of red blood cells in the micro-circulation vessels. The light from the tissues is fed to a photomultiplier tube or photodiode via a pinhole mask and interference filter. The photomultiplier tube or photodiode, as a result of beating of various components of the light it receives, produces as its output signals a homodyne or heterodyne spectrum or both. These output signals are fed, via a low pass filter, to a differentiator, which differentiates the output signals from the multiplier tube or photodiode, which are passed by the filter, with respect to time. The output of the differentiator is fed to a root-mean-square (RMS) detector. The low pass filter passes, for example, signals having a frequency up to about 20 KHz. The output (R) from the detector, which represents the blood flow (average percolation) in the tissues plus shot noise, a constant (S), is fed to a digital voltmeter. The voltmeter produces a visible read-out indicative of the output from the detector. The output from the detector is also fed to a calculating circuit which also receives a signal corresponding to the mean current (I) produced by the photomultiplier or photodiode, the calculating circuit effecting a solution to the equation ##EQU1## F norm is a normalized output signal representation of blood flow parameter.
Inventors
- 👤 Michael D. Stern
- 👤 Donald L. Lappe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 01:34
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/026; A61B5/0261; A61B5/72; A61B5/7235; A61B5/7239; G; G01; G01P; G01P3/00; G01P3/36; G01P5/00; G01P5/26
Claims Analysis
Total Claims: 47
Claim 1
Independent Claim
219 words
An apparatus for measuring blood flow in a vascular bed, the apparatus comprising: means for illuminating a region of tissue having a vascular bed with coherent light; means responsive to light backscattered from the region of tissue for producing a broadened spectrum signal output; circuit means coupled to said means for producing a broadened spectrum signal output and responsive to its broadened spectrum signal output for producing a signal representative of the blood flow in the vascular bed; means for collecting backscattered light from the region of tissue; wherein said means responsive to backscattered light comprise photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a means current and having a substantially constant shot noise output S; wherein said circuit means comprise means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof, weighted detector means coupled to said photo-detector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; and calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the blood flow in the vascular bed.
Claim 2
Independent Claim
219 words
An apparatus for measuring blood flow in a vascular bed, the apparatus comprising: means for illuminating a region of tissue having a vascular bed with coherent light; means responsive to light backscattered from the region of tissue for producing a broadened spectrum signal output; circuit means coupled to said means for producing a broadened spectrum signal output and responsive to its broadened spectrum signal output for producing a signal representative of the blood flow in the vascular bed; means for collecting backscattered light from the region of tissue; wherein said means responsive to backscattered light comprise photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a means current and having a substantially constant shot noise output S; wherein said circuit means comprise means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof, weighted detector means coupled to said photo-detector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; and calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the blood flow in the vascular bed.
Claim 3
Dependent Claim
36 words
An apparatus according to claim 1, wherein said calculating circuit comprises circuit means for producing an output signal F equal to √R 2 - SI as a representation of blood flow parameter in the vascular bed.
Claim 4
Dependent Claim
34 words
An apparatus according to claim 1, wherein said calculating circuit comprises circuit means for producing an output signal F norm equal to ##EQU18## as a representation of blood flow parameter in the vascular bed.
Claim 5
Dependent Claim
18 words
An apparatus according to claim 1, wherein said means for illuminating a region of tissue comprises a laser.
Claim 6
Dependent Claim
13 words
An apparatus according to claim 4, wherein said laser is a He-Ne laser.
Claim 7
Dependent Claim
24 words
An apparatus according to claim 4, wherein said laser is a laser which produces coherent light having a wave length of substantially 632.8 nm.
Claim 8
Dependent Claim
23 words
An apparatus according to claim 4, wherein said laser is a laser which produces light having a wave length of substantially 805 nm.
Claim 9
Dependent Claim
14 words
An apparatus according to claim 1, wherein said photo-detector means comprises a photomultiplier tube.
Claim 10
Dependent Claim
23 words
An apparatus according to claim 1, wherein said means for developing an output signal I comprises amplifier means coupled to said photo-detector means.
Claim 11
Dependent Claim
18 words
An apparatus according to claim 9, wherein said amplifier means comprises a linear amplifier having an adjustable gain.
Claim 12
Dependent Claim
15 words
An apparatus according to claim 1, wherein said weighted detector means is a root-mean-square detector.
Claim 13
Independent Claim
239 words
An apparatus for measuring blood flow in a vascular bed, the apparatus comprising: means for illuminating a region of tissue having a vascular bed with coherent light; means responsive to light backscattered from the region of tissue for producing a broadened spectrum signal output; circuit means coupled to said means for producing a broadened spectrum signal output and responsive to its broadened spectrum signal output for producing a signal representative of the blood flow in the vascular bed; and means for collecting backscattered light from the region of tissue; wherein said means responsive to backscattered light comprise photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a mean current and having a substantially constant shot noise output S; wherein said circuit means comprise means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof, weighted detector means coupled to said photodetector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; including calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the blood flow in the vascular bed, and a differentiator means and a low pass filter connected between said photo-detector means and said weighted detector means.
Claim 14
Independent Claim
239 words
An apparatus for measuring blood flow in a vascular bed, the apparatus comprising: means for illuminating a region of tissue having a vascular bed with coherent light; means responsive to light backscattered from the region of tissue for producing a broadened spectrum signal output; circuit means coupled to said means for producing a broadened spectrum signal output and responsive to its broadened spectrum signal output for producing a signal representative of the blood flow in the vascular bed; and means for collecting backscattered light from the region of tissue; wherein said means responsive to backscattered light comprise photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a mean current and having a substantially constant shot noise output S; wherein said circuit means comprise means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof, weighted detector means coupled to said photodetector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; including calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the blood flow in the vascular bed, and a differentiator means and a low pass filter connected between said photo-detector means and said weighted detector means.
Claim 15
Dependent Claim
57 words
An apparatus according to claim 12, wherein said low pass filter is connected between said photo-detector means and said differentiator means, said differentiator means having its output coupled to said weighted detector means for differentiating signals received from said low pass filter means with respect to time and supplying these differentiated signals to said weighted detector means.
Claim 16
Dependent Claim
23 words
An apparatus according to claim 13, wherein said low pass filter is an adjustable filter for passing frequencies up to about 20 KHz.
Claim 17
Independent Claim
138 words
A method of measuring the blood flow in a vascular bed, the method comprising: illuminating a region of tissue having a vasuclar bed with coherent light; collecting at least some of the scattered light from the region; detecting the collected light to determine its broadened spectrum; and determining the blood flow in the vascular bed from said broadened spectrum; wherein said detecting step comprises non-linearly detecting the backscattered light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; and wherein the determining step comprises producing a weighted output signal R from the broadened spectrum of low frequency signals, determining the shot noise constant S of the photo-detector, and producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I.
Claim 18
Independent Claim
138 words
A method of measuring the blood flow in a vascular bed, the method comprising: illuminating a region of tissue having a vasuclar bed with coherent light; collecting at least some of the scattered light from the region; detecting the collected light to determine its broadened spectrum; and determining the blood flow in the vascular bed from said broadened spectrum; wherein said detecting step comprises non-linearly detecting the backscattered light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; and wherein the determining step comprises producing a weighted output signal R from the broadened spectrum of low frequency signals, determining the shot noise constant S of the photo-detector, and producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I.
Claim 19
Dependent Claim
55 words
A method according to claim 15, wherein the illuminating step comprises illuminating a region tissue having a microvascular bed, the collecting step comprises collecting at least some of the scattered light from the microvascular bed, and the determining step comprises determining the flow of red blood cells in the microvascular bed from said broadened spectrum.
Claim 20
Dependent Claim
32 words
A method according to claim 15, wherein the producing step comprises producing an output F equal to √R 2 - SI as a representation of blood flow parameter in the vascular bed.
Claim 21
Dependent Claim
31 words
A method according to claim 15, wherein the producing step comprises producing a normalized output F norm equal to ##EQU19## as a representation of blood flow parameter in the vascular bed.
Claim 22
Dependent Claim
28 words
A method according to claim 15, wherein said illuminating step comprises illuminating a region of the tissue with coherent light having a wave length of substantially 632.8 nm.
Claim 23
Dependent Claim
28 words
A method according to claim 15, wherein said illuminating step comprises illuminating a region of the tissue with coherent light having a wave length of substantially 805 nm.
Claim 24
Dependent Claim
34 words
A method according to claim 15, wherein the step of detecting the broadened spectrum of low frequency signals comprises detecting the broadened spectrum of low frequency signals to produce a root-mean-square output signal R.
Claim 25
Dependent Claim
33 words
A method according to claim 15, including filtering the broadened spectrum of low frequency signals to pass only signals below a given frequency prior to detecting the broadened spectrum of low frequency signals.
Claim 26
Independent Claim
184 words
A method of measuring the blood flow in a vascular bed, the method comprising: illuminating a region of tissue having a vascular bed with coherent light; collecting at least some of the scattered light from the region; detecting the collected light to determine its broadened spectrum; determining the blood flow in the vascular bed from said broadened spectrum; wherein said detecting step comprises non-linearly detecting the backscattered light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; and wherein the determining step comprises producing a weighted output signal R from the broadened spectrum of low frequency signals, determining the shot noise constant S of the photo-detector, and producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I; filtering the broadened spectrum of low frequency signals to pass only signals below a given frequency prior to detecting the broadened spectrum of low frequency signals; and differentiating the filtered low frequency signals with respect to time prior to detecting the broadened spectrum of low frequency signals.
Claim 27
Independent Claim
184 words
A method of measuring the blood flow in a vascular bed, the method comprising: illuminating a region of tissue having a vascular bed with coherent light; collecting at least some of the scattered light from the region; detecting the collected light to determine its broadened spectrum; determining the blood flow in the vascular bed from said broadened spectrum; wherein said detecting step comprises non-linearly detecting the backscattered light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; and wherein the determining step comprises producing a weighted output signal R from the broadened spectrum of low frequency signals, determining the shot noise constant S of the photo-detector, and producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I; filtering the broadened spectrum of low frequency signals to pass only signals below a given frequency prior to detecting the broadened spectrum of low frequency signals; and differentiating the filtered low frequency signals with respect to time prior to detecting the broadened spectrum of low frequency signals.
Claim 28
Independent Claim
147 words
An apparatus for measuring the flow of flowing material, the apparatus comprising: means for illuminating at least a portion of the flowing material with coherent light; means for collecting backscattered light from the material; photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a mean current and having a substantially constant shot noise output S; means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof; weighted detector means coupled to said photo-detector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; and calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the flow.
Claim 29
Independent Claim
147 words
An apparatus for measuring the flow of flowing material, the apparatus comprising: means for illuminating at least a portion of the flowing material with coherent light; means for collecting backscattered light from the material; photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a mean current and having a substantially constant shot noise output S; means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof; weighted detector means coupled to said photo-detector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; and calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the flow.
Claim 30
Dependent Claim
31 words
An apparatus according to claim 24, wherein said calculating circuit comprises circuit means for producing an output signal F equal to √R 2 - SI as a representation of flow parameter.
Claim 31
Dependent Claim
29 words
An apparatus according to claim 24, wherein said calculating circuit comprises circuit means for producing an output signal F norm equal to ##EQU20## as a representation of flow parameter.
Claim 32
Dependent Claim
14 words
An apparatus according to claim 24, wherein said photo-detector means comprises a photomultiplier tube.
Claim 33
Dependent Claim
23 words
An apparatus according to claim 24, wherein said means for developing an output signal I comprises amplifier means coupled to said photo-detector means.
Claim 34
Dependent Claim
18 words
An apparatus according to claim 28, wherein said amplifier means comprises a linear amplifier having an adjustable gain.
Claim 35
Dependent Claim
15 words
An apparatus according to claim 24, wherein said weighted detector means is a root-mean-square detector.
Claim 36
Independent Claim
165 words
An apparatus for measuring the flow of flowing material, the apparatus comprising: means for illuminating at least a portion of the flowing material with coherent light; means for collecting backscattered light from the material; photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a mean current and having a substantially constant shot noise output S; means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof; weighted detector means coupled to said photodetector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the flow; and a differentiator means and a low pass filter connected between said photo-detector means and said weighted detector means.
Claim 37
Independent Claim
165 words
An apparatus for measuring the flow of flowing material, the apparatus comprising: means for illuminating at least a portion of the flowing material with coherent light; means for collecting backscattered light from the material; photo-detector means responsive to the collected light for developing a broadened spectrum of low frequency signals, said photo-detector means producing a mean current and having a substantially constant shot noise output S; means coupled to said photo-detector means and responsive to its output for developing an output signal I representative of the mean current thereof; weighted detector means coupled to said photodetector and responsive to the broadened spectrum of low frequency signals for developing an output signal R; calculating circuit means coupled to said weighted detector means and to said means for developing an output signal I and responsive to outputs thereof for producing an output signal F representative of the flow; and a differentiator means and a low pass filter connected between said photo-detector means and said weighted detector means.
Claim 38
Dependent Claim
57 words
An apparatus according to claim 31, wherein said low pass filter is connected between said photo-detector means and said differentiator means, said differentiator means having its output coupled to said weighted detector means for differentiating signals received from said low pass filter means with respect to time and supplying these differentiated signals to said weighted detector means.
Claim 39
Dependent Claim
23 words
An apparatus according to claim 32, wherein said low pass filter is an adjustable filter for passing frequencies up to about 20 KHz.
Claim 40
Independent Claim
105 words
A method of measuring the flow parameter of flowing material, the method comprising: illuminating at least a portion of the flowing material with coherent light; collecting at least some of the light scattered from the material; non-linearly detecting the collected light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; detecting the broadened spectrum of low frequency signals to produce a weighted output signal R; determining the shot noise constant S of the photodetector; and producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I.
Claim 41
Independent Claim
105 words
A method of measuring the flow parameter of flowing material, the method comprising: illuminating at least a portion of the flowing material with coherent light; collecting at least some of the light scattered from the material; non-linearly detecting the collected light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; detecting the broadened spectrum of low frequency signals to produce a weighted output signal R; determining the shot noise constant S of the photodetector; and producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I.
Claim 42
Dependent Claim
27 words
A method according to claim 34, wherein the producing step comprises producing an output F equal to √R 2 - SI as a representation of flow parameter.
Claim 43
Dependent Claim
26 words
A method according to claim 34, wherein the producing step comprises producing a normalized output F norm equal to ##EQU21## as a representation of flow parameter.
Claim 44
Dependent Claim
34 words
A method according to claim 36, wherein the step of detecting the broadened spectrum of low frequency signals comprises detecting the broadened spectrum of low frequency signals to produce a root-mean-square output signal R.
Claim 45
Dependent Claim
33 words
A method according to claim 34, including filtering the broadened spectrum of low frequency signals to pass only signals below a given frequency prior to detecting the broadened spectrum of low frequency signals.
Claim 46
Independent Claim
179 words
A method of measuring the flow parameter of flowing material, the method comprising: illuminating at least a portion of the flowing material with coherent light; collecting at least some of the light scattered from the material; non-linearly detecting the collected light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; detecting the broadened spectrum of low frequency signals to produce a weighted output signal R; determining the shot noise constant S of the photo-detector; producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I; wherein the step of detecting the broadened spectrum of low frequency signals comprises detecting the broadened spectrum of low frequency signals to produce a root-mean-square output signal R; filtering the broadened spectrum of low frequency signals to pass only signals below a given frequency prior to detecting the broadened spectrum of low frequency singals, and differentiating the filtered low frequency signals with respect to time prior to detecting the broadened spectrum of low frequency signals.
Claim 47
Independent Claim
179 words
A method of measuring the flow parameter of flowing material, the method comprising: illuminating at least a portion of the flowing material with coherent light; collecting at least some of the light scattered from the material; non-linearly detecting the collected light in a photo-detector to produce a broadened spectrum of low frequency signals and a mean current signal I; detecting the broadened spectrum of low frequency signals to produce a weighted output signal R; determining the shot noise constant S of the photo-detector; producing a signal representation F, from the shot noise constant, the weighted output signal R and the mean current signal I; wherein the step of detecting the broadened spectrum of low frequency signals comprises detecting the broadened spectrum of low frequency signals to produce a root-mean-square output signal R; filtering the broadened spectrum of low frequency signals to pass only signals below a given frequency prior to detecting the broadened spectrum of low frequency singals, and differentiating the filtered low frequency signals with respect to time prior to detecting the broadened spectrum of low frequency signals.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-08-28 | 1982-02-27 | 1982-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-08-28 | 1986-02-27 | 1986-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-08-28 | 1990-02-27 | 1990-08-29 | $7700.00 | Window Closed / Lapsed |