Method for the determination of a light transport parameter in a biological matrix

• US 20040152089A1
• Filed: 03/12/2004
• Published: 08/05/2004
• Est. Priority Date: 03/06/2001
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Volz, Dietmar, Hein, Heinz-Michael, Kraemer, Uwe
• Granted Patent: US 7,565,249 B2
• Time in Patent Office: Days
• US Class Current: 435/6
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A method for the selective determination of a light transport parameter which is characteristic for the light scattering in a biological matrix (5), in particular for the purpose of the non-invasive determination of the glucose concentration in the biological matrix. It comprises a plurality of detection measurements, in which light is irradiated as primary light into the biological matrix and an intensity value of secondary light emerging at a detection site, located in different measuring distances from the irradiation site, is measured. In an evaluation step, the light transport parameter is derived, by means of an evaluation algorithm, from the measured intensity values. For the selective determination of the scattering coefficient, the evaluation algorithm includes a step in which a time derivative value Δ_tI(r) describing the change of the measurement intensity value versus time is calculated from intensity measurement values obtained at a minimum of two different points of time.

Claims

1. Method for the selective determination of a light transport parameter which is characteristic for the light scattering in a biological matrix (5), in particular for the purpose of the non-invasive determination of the glucose concentration in the biological matrix (5), comprising

a plurality of detection measurements in which light is irradiated as primary light (9) at an irradiation site (10) into the biological matrix (5), the light propagates inside the biological matrix along a light path (20 to 22) and an intensity measurement value of light emerging as secondary light at a detection site (12 to 14) which in the plurality of detection measurements is located at different measuring distances (r₁ to r₃) from the irradiation site is measured;

and

an evaluation step in which the light transport parameter is is derived from the intensity values measured during the plurality of detection measurements by means of an evaluation algorithm,

characterized in that

the evaluation algorithm includes a step in which a time derivative value Δ

_tI(r) describing the change of the intensity measurement value versus time, is calculated from intensity measurement values obtained at a minimum of two different points of time, and the time derivative value is used for the determination of the light transport parameter.

2. Method according to claim 1, characterized in that the evaluation algorithm includes steps, in which a time derivative value is calculated for at least two different measuring distances between irradiation site and detection site, and that the spatial derivative of the time derivative value with respect to the measuring distance is calculated therefrom.

3. Method according to claim 2, characterized in that each of the at least two measuring distances is shorter than the fourfold, preferably shorter than the threefold, mean free path of the light in the biological matrix.

4. Method according to claim 1, characterized in that the evaluation algorithm includes steps, in which a time derivative value is calculated for at least three different measuring distances between irradiation site and detection site, and that the second spatial derivative of the time derivative value with respect to the measuring distance is calculated therefrom.

5. Method according to claim 4, characterized in that each of the at least three measuring distances is shorter than the fourfold, preferably shorter than the threefold, mean free path of the light in the biological matrix.

6. Method according to claim 4 or 5, characterized in that, for the at least three detection measurements, the measuring distances between the respective irradiation and detection sites differ by the same value.

7. Method according to any one of the preceding claims, characterized in that at least one of the measuring distances is shorter than the mean free path of the light in the biological matrix.

8. Computer program product, to be loaded directly into the memory of a digital computer, comprising software sections processing the steps of the method according to any one of the claims 1 to 7, if the product runs on a computer.

9. Computer-appropriate storage medium with a computer program product according to claim 8.

10. Device for the optical analysis of a biological matrix, containing a computer program product according to claim 8.