SPECTROMETRIC SYSTEMS AND METHODS FOR IMPROVED FOCUS LOCALIZATION OF TIME- AND SPACE-VARYING MEASUREMENTS

• US 20150109617A1
• Filed: 04/29/2013
• Published: 04/23/2015
• Est. Priority Date: 04/30/2012
• Status: Active Grant

• Current Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Original Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Inventors: Gilbert, Barry K., Haider, Clifton R., Delp, Gary S., Rose, James A.
• Granted Patent: US 9,739,663 B2
• Time in Patent Office: Days
• US Class Current: 356/300
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: G01J 3/0237 Adjustable, e.g. focussing
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01N 21/49 within a body or fluid
• CPC Class Codes: G01N 33/4925 measuring blood gas content, e.g. O2, CO2 , HCO3

Abstract

A system and method of dynamically localizing a measurement of parameter characterizing tissue sample with waves produced by spectrometric system at multiple wavelengths and detected at a fixed location of the detector of the system. The parameter is calculated based on impulse response of the sample, reference data representing characteristics of material components of the sample, and path lengths through the sample corresponding to different wavelengths. Dynamic localization is effectuated by considering different portions of a curve representing the determined parameter, and provides for the formation of a spatial map of distribution of the parameter across the sample. Additional measurement of impulse response at multiple detectors facilitates determination of change of the measured parameter across the sample as a function of time.

Claims

1. A method for determining a characteristic of a biological sample with a spectrometric system, the spectrometric system including at least one transmitter and at least one receiver, the method comprising:

receiving, with a data-processing unit of the system, an output from the at least one receiver caused by emission, by the transmitter, of at least one electromagnetic wave (EMW) at at least one corresponding wavelength, the at least one transmitter and the at least one receiver being operably juxtaposed with the sample, the output representing an optical property of the sample;

receiving, with the data-processing unit of the system, reference data representing empirically-defined spectrally-dependent characteristic of the sample;

determining an impulse response of the sample, the impulse response being associated with emission of the at least one EMW by the at least one transmitter; and

determining, as a function of time, a wavelength-dependent material parameter characterizing the sample based on the determined impulse response and the reference data

2. A method according to claim 1, wherein the optical property includes at least one of wavelength-dependent scattering, absorption, and anisotropy of the sample.

3. A method according to claim 1, wherein the determining, as a function of time, a wavelength-dependent material parameter characterizing the sample includes determining a wavelength-dependent material parameter characterizing the sample based on the averaged wavelength-dependent path length that has been estimated with the use of the determined impulse response.

4. A method according to claim 3, further comprising

sampling a curve representing the determined wavelength-dependent material parameter as a function of time to obtain values of said material parameter at sampled points in time, and

forming a weighting function by calculating variance values among the values of said material parameter at sample points in time, the weighting function being defined by said variance values as a function of time.

5. A method according to claim 4, further comprising

modifying the wavelength-dependent material parameter characterizing the sample based on (i) the computed impulse response that has been weighted by the weighting function and (ii) the reference data.

6. A method according to claim 1, wherein the at least one material parameter includes one or more of a level of oxygenation of the sample and a concentration of a chosen species in the sample.

7. A method according to claim 1, wherein, when the sample has received a substance composition, the determining at least one material parameter characterizing the sample includes determining a concentration of the substance composition as a proxy for a material, the material concentration of which is being determined.

8. A method according to claim 1, wherein the determining an impulse response includes determining an impulse response of the sample based on the output, the output being a time-dependent characteristic of a pair formed by the at least one transmitter and the at least one receiver, the pair identified at the data-processing unit of the system by a respectively corresponding excitation sequence series of pulses associated with the at least one transmitter.

9. A method according to claim 1, further comprising forming a spatial map of the determined material parameter across a cross-section of the sample located between the at least one transmitter and the at least one receiver based on different portions of a curve representing said material parameter as a function of time.

10. A method for operating a spectrometric device configured to generate electromagnetic waves (EMWs) and juxtaposed with a sample such as to measure at least one property associated with at least one material component of the sample using at least one of the EMWs, the method comprising:

in response to a first excitation sequence of pulses generated by a unit of the spectrometric device, transmitting a first EMW at a first wavelength by a transmitter associated with the spectrometric device;

concurrently with transmitting the first EMW and in response to a second excitation sequence of pulses generated by the unit of the spectrometric device, transmitting a second EMW at a second wavelength by a transmitter associated with the spectrometric device;

acquiring said first and second transmitted EMWs as an aggregated input with a receiver associated with the spectrometric device; and

processing the received aggregated input with a data-processing unit associated with the spectrometric device by;

correlating the aggregated input with a time-controlled representation of the first excitation sequence of pulses to form a time based vector;

correlating the aggregated input with a time-controlled representation of the second excitation sequence of pulses to form a second time-based vector;

calculating, based at least on first and second time based vector, the at least one property associated with the at least one material components of the sample.

11. An optical-path adjustment apparatus for modifying an optical path between a source of light and a receiver of light, the apparatus comprising:

the source of light including at least one transmitter enabled to emit a corresponding beam light at at least one corresponding wavelength;

the receiver of light in optical communication with the at least one transmitter; and

a device including

a first plurality of selectively reorientable reflectors disposed such that, when each of the reflectors from the first plurality is in a corresponding reference orientation, the first plurality defines a first surface;

a second plurality of selectively reorientable reflectors disposed such that, when each of the reflectors from the second plurality is in a corresponding reference orientation, the second plurality defines a second surface that is transverse to the first surface and substantially parallel to the corresponding beam of light,

the first and second pluralities being in optical communication with the at least one transmitter such as to enable the apparatus to scan the corresponding beam of light which, when a reflector of the first plurality and a reflector of the second plurality are reoriented with respect to the corresponding reference orientations, has interacted with the reflector of the first plurality after having interacted with the reflector of the second plurality.

12. An apparatus according to claim 11, wherein the first and second pluralities are in such optical communication with the optical receiver that light from the corresponding beam of light, that has been scattered by an imaginary group of scattering points, is received by the optical receiver after interacting with a reflector of the first plurality, wherein an optical path of said received light defined between the at least one transmitter and the optical receiver is adjustable by a choice of the reflector of the first plurality.

13. An apparatus according to claim 11, wherein at least one of the first and second pluralities includes reflectors organized in rows.

14. An apparatus according to claim 11, wherein the first and second pluralities includes reflectors organized in rows, and the rows of the first plurality are staggered with respect to one another.

15. An apparatus according to claim 11, wherein the first and second pluralities are positioned to align at least one reflector of the second plurality and a row of reflectors of the first plurality in a plane.

16. An apparatus according to claim 11, further comprising

a third plurality of selectively reorientable reflectors disposed such that, when each of the reflectors from the third plurality is in a corresponding reference orientation, the third plurality defines a third surface that is transverse to the first surface;

the first and third pluralities being in optical communication with the optical receiver such as to redirect a beam of light, received and reflected by a reflector of the first plurality that has been reoriented with respect to the reference orientation to apparatus, towards the optical receiver upon reflection from a reflector of the third plurality that has been reoriented with respect to the corresponding reference orientation.

17. An optical-data-collection apparatus comprising:

an optical detector;

a light irradiation system enabled to deliver a beam of light from a starting point to the optical detector such as to scan an object that has been positioned at an intermediate point along a direction of propagation of the beam between the starting point and the optical detector, the light irradiation system including

at least one light transmitter defining the starting point, and

a plurality of spatially reorientable reflectors disposed such that, when at least three of said reflectors are in respectively corresponding reference states of orientation, the at least three of said reflector define a plane that is substantially parallel to the beam of light,

wherein the light irradiation system enables controlling a distance traversed by the delivered beam that has scanned the object by reflecting the beam with a reflector from the plurality to redirect the beam towards the optical detector.

18. An apparatus according to claim 17, further comprising

a second plurality of selectively reorientable reflectors disposed such that, when at least three of the reflectors from the second plurality are in respectively corresponding reference orientations, the second plurality defines a second plane that is transverse to the first plane and substantially parallel to the corresponding beam of light,

the second plurality being in optical communication with the optical detector such that, when a reflector of the first plurality and a reflector of the second plurality are reoriented with respect to the corresponding reference orientations, the delivered beam has interacted with the reflector of the first plurality after having interacted with the reflector of the second plurality.