Analysis of Optical Data with the Aid of Histograms

• US 20090116015A1
• Filed: 10/08/2008
• Published: 05/07/2009
• Est. Priority Date: 04/08/2006
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Asfour, Jean-Michel, Petrich, Wolfgang, Kocherscheidt, Gerrit, Haar, Hans-Peter
• Granted Patent: US 7,889,329 B2
• Time in Patent Office: Days
• US Class Current: 356/416
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04
• CPC Class Codes: G06T 2207/10056 Microscopic image
• CPC Class Codes: G06T 2207/30024 Cell structures in vitro; Tissue sections in vitro
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/41 based on statistical description of texture

Abstract

A system for determining the concentration of an analyte in a liquid sample comprising a detection unit for detecting light intensities which are radiated from subareas of a detection area of a test element as well as an evaluation unit which determines a frequency distribution for the detected light intensities wherein the frequency distribution has at least one first maximum caused by unwetted subareas or at least one reference area and a second maximum caused by wetted subareas and selects at least one light intensity on the basis of the frequency distribution and determines the concentration of the analyte from the at least one selected light intensity.

Claims

1. A system for determining the concentration of an analyte in a liquid sample comprising:

a detection unit for detecting light intensities which are radiated from subareas of a detection area of a test element; and

an evaluation unit which determines a frequency distribution for the detected light intensities wherein the frequency distribution has at least one first maximum caused by one of at least one unwetted subarea and at least one reference area and a second maximum caused by subareas wetted by a sample and at least one light intensity is selected on the basis of the frequency distribution and the concentration of the analyte is determined from the at least one selected light intensity.

2. The system according to claim 1, wherein the concentration of the analyte is determined on the basis of intensity frequencies present at one of after applying the sample to the detection area and before and after applying the sample to the detection area.

3. The system according to claim 1, wherein the test element contains a reagent which is substantially homogeneously distributed throughout the detection area.

4. The system according to claim 1, wherein the sample has a volume of between 0.1 and 500 nl.

5. The system according to claim 1, wherein the concentration of the analyte is determined on the basis of rates of changes in the frequencies of the radiated light intensities after wetting the detection area.

6. The system according to claim 1, wherein the concentration of the analyte is determined on the basis of the maximums of the frequency distribution of the intensities before and after wetting the detection area.

7. The system according to claim 1, wherein the analysis is carried out using multivariate analytical methods.

8. The system according to claim 1, wherein a slope of an intensity gradient between a lowest intensity and a most frequent intensity is used to determine the analyte concentration.

9. The system according to claim 1, wherein the concentration of the analyte is determined on the basis of intensities which exceed a frequency threshold value.

10. The system according to claim 1, wherein a frequency distribution determined before the sample is applied to the test element is compared to a frequency distribution determined after the sample is applied to the test element to determine a quality characteristic of the test element.

11. The system according to claim 1, wherein an adequate wetting of the detection area is determined on the basis of exceeding a certain frequency of intensities which change after sample application.

12. The system according to claim 10, wherein the frequency distribution determined before the sample is applied to the test element indicates an adequate homogeneity of the detection area.

13. The system according to claim 1, wherein an analysis of the detection area is carried out when a rate of change of frequencies is below a rate threshold value after application of the sample to the detection area.

14. A method for determining the concentration of an analyte in a liquid comprising the steps of:

applying a liquid to a detection area of a test element;

detecting light intensities of the light radiated from subareas of the detection area;

determining a frequency distribution of the detected light intensities, wherein the frequency distribution has at least one first maximum caused by one of at least one unwetted subarea and at least one reference area and a second maximum caused by wetted subareas; and

calculating the concentration of the analyte on the basis of at least one light intensity which was selected on the basis of its frequency.

15. The method according to claim 14, further including the step of determining a frequency distribution of light intensities before the applying step.

16. The method according to claim 15, further including the step of determining a quality characteristic of the test element based on the frequency distribution determined before the applying step.

17. A method for the quality control of a detection area of a test element comprising the steps of:

detecting light intensities of light radiated from unwetted subareas of a detection area;

calculating a frequency distribution of the detected light intensities; and

comparing the frequency distribution with quality criteria.

18. The method according to claim 17, wherein a proportion of frequencies which are within a certain intensity interval is determined.

19. The method according to claim 18, wherein the test element is not used when the proportion of frequencies within the interval does not exceed an interval threshold value.

20. An instrument for determining the concentration of an analyte in a liquid sample comprising:

a detection unit for detecting light intensities which are radiated from subareas of a detection area of a test element; and

an evaluation unit which determines a frequency distribution for the detected light intensities wherein the frequency distribution has at least one first maximum caused by one of at least one unwetted subarea and at least one reference area and a second maximum caused by wetted subareas;

wherein the evaluation unit is integrated into the detection unit.

21. The instrument according to claim 20, wherein the evaluation unit is integrated on a chip.

22. The instrument according to claim 21, wherein the detection unit contains a CMOS detector which is integrated on the chip together with at least one A/D converter.