Method and system for examining biological materials using low power CW excitation Raman spectroscopy
First Claim
1. A method of examining an object, said method comprising the steps of:
- (a) irradiating the object with a first pump beam at a first wavelength, whereby the object produces a spontaneous Raman emission at a second wavelength;
(b) substantially simultaneously with step (a), irradiating the object with a first probe beam at a third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said second wavelength;
(c) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (a) and (b), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said first wavelength;
(d) irradiating the object with a second pump beam at a fourth wavelength, whereby the object produces a spontaneous Raman emission at a fifth wavelength, said fourth wavelength not being equal to said first wavelength;
(e) substantially simultaneously with step (d), irradiating the object with said first probe beam at said third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said fifth wavelength; and
(f) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (d) and (e), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said fourth wavelength;
(g) wherein said first pump beam and said second pump beam are generated using a wavelength-tunable laser.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. A low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 104-106) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic transaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively.
-
Citations
25 Claims
-
1. A method of examining an object, said method comprising the steps of:
-
(a) irradiating the object with a first pump beam at a first wavelength, whereby the object produces a spontaneous Raman emission at a second wavelength;
(b) substantially simultaneously with step (a), irradiating the object with a first probe beam at a third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said second wavelength;
(c) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (a) and (b), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said first wavelength;
(d) irradiating the object with a second pump beam at a fourth wavelength, whereby the object produces a spontaneous Raman emission at a fifth wavelength, said fourth wavelength not being equal to said first wavelength;
(e) substantially simultaneously with step (d), irradiating the object with said first probe beam at said third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said fifth wavelength; and
(f) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (d) and (e), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said fourth wavelength;
(g) wherein said first pump beam and said second pump beam are generated using a wavelength-tunable laser. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
(g) irradiating the object with a pump beam at a wavelength other than said first wavelength and said fourth wavelength;
(h) substantially simultaneously with step (g), irradiating the object with said first probe beam at said third wavelength;
(i) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (g) and (h);
(j) repeating steps (g) through (i) until a spectrum of different pump beam wavelengths have been used; and
(k) generating an excitation Raman spectrum for the object using the intensities detected in steps (c), (f) and (i).
-
-
3. The method as claimed in claim 2 wherein the object is a biological material.
-
4. The method as claimed in claim 2 wherein the object is a blood sample.
-
5. The method as claimed in claim 4 further comprising the step of comparing the detected intensities at one or more of the Raman modes for blood glucose to appropriate standards so that the concentration of blood glucose in the blood sample can be determined.
-
6. The method as claimed in claim 4 further comprising the step of comparing the detected intensities at one or more of the Raman modes for serum cholesterol to appropriate standards so that the concentration of serum cholesterol in the blood sample can be determined.
-
7. The method as claimed in claim 4 further comprising the step of comparing the detected intensities at one or more of the Raman modes for serum glutamic oxalacetic transaminase and serum glutamic pyruvic transaminase to appropriate standards so that the concentrations of serum glutamic oxalacetic transaminase and serum glutamic pyruvic transaminase in the blood sample can be determined.
-
8. The method as claimed in claim 4 further comprising the step of comparing the detected intensities at one or more of the Raman modes for blood urea nitrogen to appropriate standards so that the concentration of blood urea nitrogen in the blood sample can be determined.
-
9. The method as claimed in claim 4 further comprising the step of comparing the detected intensities at one or more of the Raman modes for creatinine to appropriate standards so that the concentration of creatinine in the blood sample can be determined.
-
10. The method as claimed in claim 4 further comprising the step of comparing the detected intensities at one or more of the Raman modes for acid phosphatase to appropriate standards so that the concentration of acid phosphatase in the blood sample can be determined.
-
11. The method as claimed in claim 3 wherein the biological material is a tissue sample, said method further comprising the step of comparing said excitation Raman spectrum to appropriate standards obtained for cancerous and noncancerous tissues of the same type.
-
12. The method as claimed in claim 11 wherein the tissue sample is a human breast tissue sample.
-
13. The method as claimed in claim 11 wherein the tissue sample is a human cervical tissue sample.
-
14. The method as claimed in claim 11 wherein the tissue sample is a human uterine tissue sample.
-
15. The method as claimed in claim 11 wherein the tissue sample is a human ovarian tissue sample.
-
16. The method as claimed in claim 3 wherein the biological material is a urine, lymph, saliva, semen or tear sample.
-
17. The method as claimed in claim 3 wherein the biological material is a human aortic tissue sample, said method further comprising the step of comparing said excitation Raman spectrum to appropriate standards obtained for normal human aortic tissue, calcified human plaque tissue and fibrous human plaque tissue.
-
18. The method as claimed in claim 1 wherein the object examined is part of a living being and wherein said method is performed in vivo.
-
19. The method as claimed in claim 1 further comprising the step of comparing the intensities detected in steps (c) and (f) to the intensity of said first probe beam emitted from the object at said third wavelength in the absence of a pump beam.
-
20. The method as claimed in claim 1 wherein one of said first and said fourth wavelengths is a known Raman mode for the object being examined and wherein the other of said first and said fourth wavelengths is known not to be a Raman mode for the object being examined.
-
21. The method as defined in claim 1, wherein said object is a body part, said examining is done in vivo and said method further comprises:
-
(a) modulating the blood quantity in the examining region by decreasing or increasing the blood flow;
(b) measuring the Raman spectra of the examining region at different blood flow conditions; and
(c) comparing the Raman intensities of the same area for different blood flow conditions to determine the blood glucose level.
-
-
22. The method as claimed in claim 21 wherein said body part is selected from the group consisting of an ear, a finger, an arm and a leg.
-
23. A method of determining glucose quantity in the test region of an in-vivo examining human body part where the blood flow can be decreased or increased comprising:
-
(a) obtaining a Raman spectrum for the test region with a pump beam only while the blood flow to the test region is decreased or increased, and (b) comparing the Raman spectrum obtained in step (a) with a corresponding Raman spectrum for the same region under a normal blood flow condition to determine blood glucose concentration.
-
-
24. A method of examining levels of blood glucose, cholesterol or other blood analytes in vivo in a body part such as a finger, ear, arm or leg, said method comprising the steps of:
-
(a) irradiating a test area of said body part without any pressure on said body part with a first pump beam at a first wavelength, whereby said body part produces a spontaneous Raman emission forming a first Raman spectrum with the contribution from the glucose, cholesterol or other blood constituents, (b) pulling the body part so that the test area has less blood, (c) irradiating the test area of the body part with the first pump beam at the first wavelength, whereby the test area of the body part produces a spontaneous Raman emission forming a second Raman spectrum with a lesser contribution from the glucose, cholesterol or other blood constituents, (d) detecting and recording the first and second Raman spectra, (e) subtracting the second Raman spectrum (obtained from the test area with a less blood condition) from the first Raman spectrum (obtained from the test area with a normal blood flowing condition), the resulting spectrum, namely, difference Raman spectrum has improved signal-to-noise ratio because the contribution of the tissue components and structures to the Raman spectrum is reduced due to the subtraction, and then (f) analyzing the difference Raman spectrum, (g) comparing the detected intensities at one or more of the Raman modes for blood analytes to appropriate standards, and (h) determining the levels of glucose, cholesterol or other blood constituents using said comparisons obtained.
-
-
25. A method of examining levels of blood glucose, cholesterol or other blood analytes in vivo in a body part such as a finger, ear, arm or leg, said method comprising steps of:
-
(a) irradiating a test on said finger, ear, arm, leg, or other body part without any pressure on the body part with a first pump beam at a first wavelength, whereby the body part produces a spontaneous Raman emission forming a first Raman spectrum with the contribution from the glucose, cholesterol or other blood constituents;
(b) pushing the same test area of the finger, ear, arm, leg, or other body part so that the test area has more blood, or tightening a rubber band or belt around the test area so that the test area has more blood, (c) irradiating the finger, ear, arm, leg, or other body part with the said first pump beam at the said first wavelength, whereby the test area of the body part produces a spontaneous Raman emission forming a third Raman spectrum with a higher contribution form the glucose, cholesterol or other blood constituents;
(d) detecting and recording the said first and the third Raman spectra;
(e) taking the difference between the said first Raman spectrum and the third Raman spectrum, the resulting spectrum, namely difference Raman spectrum having a better single-to-noise ration;
(f) analyzing the said difference Raman spectrum, (g) comparing the detected intensities at one or more of the Raman modes for blood analytes to appropriate standards, and (h) determining the levels of glucose, cholesterol or other blood constituents.
-
Specification