Method and System for Measuring a Composition in a Blood Fluid

• US 20100331637A1
• Filed: 04/13/2009
• Published: 12/30/2010
• Est. Priority Date: 04/16/2008
• Status: Abandoned Application

• Current Assignee: Glucostats System Pte., Ltd.
• Original Assignee: Glucostats System Pte., Ltd.
• Inventors: RAVEENDRAN, Paramesran, TING, Choon Meng
• Application Number:
  US12/918,315
• Publication Number:
  US 20100331637A1
• Time in Patent Office: Days
• US Class Current: 600/316
• 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: A61B 5/7267 involving training the classification device
• CPC Class Codes: G06N 3/045 Combinations of networks
• CPC Class Codes: G16H 10/40 for data related to laboratory analysis, e.g. patient specimen analysis
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

A system (10) and method for measuring a composition in the blood fluid is disclosed. The system (10) comprises a non-invasive measuring unit (12) for measuring the composition; and at least one neural network (16) for processing a plurality of measurements taken by the non-invasive measuring unit (12) to determine an overall measurement of the composition in the blood fluid. A further aspect of the invention discloses a computer-readable medium for performing the above method.

Claims

1. A system for measuring a composition of a blood fluid comprising:

at least one neural-network for processing a plurality of measurements taken by a non-invasive measuring unit to determine an overall measurement of the composition in the blood fluid, wherein a linear equation associated with each output node of the at least one neural network is determined from a controlled source prior to training the at least one neural network.

4. A system or method for measuring a composition in the blood fluid according to any of claim 1 to 3, wherein the linear equation associated with each output node is obtained based on a line of best fit.

5. A system or method for measuring a composition in the blood fluid according to any of claim 1 to 4, where the linear equation associated with each hidden node is determined through automated processes.

6. A system or method for measuring a composition in the blood fluid according to any one of claims 1 to 5, where the at least one neural network implements a back propagation algorithm.

7. A system or method for measuring a composition in the blood fluid according to claim 5, where the number of nodes in an input layer of the at least one neural network matches the number of measurements in the plurality of measurements taken by the non-invasive measuring unit.

8. A system or method for measuring a composition in the blood fluid according to any one of claim 5 to 7, where the at least one neural network comprises at a hidden layer of at least four nodes.

9. A system or method for measuring a composition in the blood fluid according to any one of claims 6 to 8, where the output value for the hidden node is a summation of weighted measurements.

10. A system or method for measuring a composition in the blood fluid according to any one of claims 6 to 9, where the output value for the output node is a summation of weighted normalized hidden node output values.

11. A system or method for measuring a composition in the blood fluid according to any one of claims 6 to 10, where the adjustments to the weightings for each link between a hidden node and an output node are calculated with reference to an output gradient error.

12. A system or method for measuring a composition in the blood fluid according to claim 11, where the output gradient error is calculated as follows:

δ

_k=(t_k−

n_k)·

n_k·

(1−

n_k)

where;

δ

_k is the output gradient error

n_k is the normalized output value for output node k.

t_k is the target output value for output node k as determined by the linear equation associated with output node k.

13. A system or method for measuring a composition in the blood fluid according to claim 12, where the adjustment to the weightings for each link between a hidden node and an output node are calculated according to the formula:

Δ

who_jk(p+1)=η

·

δ

_k·

f(net_j)+m·

Δ

who_jk(p)

where;

η

denotes the learning rate.

m denotes the momentum composition.

δ

_k is the output gradient error.

who_jk(p+1) represents the updated change in weight.

who_jk(p) represents the previous change in weight.

f(net_j) is the normalized output value for hidden node j.

14. A system or method for measuring a composition in the blood fluid according to any one of claims 6 to 13, where the adjustments to the weightings for each link between an input node and a hidden node are calculated with reference to a hidden layer gradient error.

15. A system or method for measuring a composition in the blood fluid according to claim 14, where the hidden layer gradient error is calculated as follows:

16. A system or method for measuring a composition in the blood fluid according to claim 15, where the adjustments to the weightings for each link between an input node and a hidden node are calculated as follows:

Δ

wih_ij(p+1)=η

·

δ

_j·

x_i+mΔ

wih_ij(p)

where;

η

denotes the learning rate.

m denotes the momentum composition.

δ

_j is the hidden layer gradient error.

x_i is the value of input node i.

wih_ij(p+1) represents the updated change in weight.

wih_ij(p) represents the previous change in weight.

17. A system or method for measuring a composition in the blood fluid according to claim 13 or claim 16, where the learning rate (η

) and the momentum parameter (m) are automatically adjusted during training.

18. A system or method for measuring a composition in the blood fluid according to claim 13, claim 16 or claim 17, where the learning rate (η

) is a value in the range 0.01 to 0.1 and the momentum parameter (m) is a value in the range 0.8 to 0.9.

19. A system or method for measuring a composition in the blood fluid according to any one of claims 6 to 18, where the at least one neural network comprises at least one bias.

20. A system or method for measuring a composition in the blood fluid according to claim 19, as dependent on claim 9, where the output value for the hidden node is a summation of weighted measurements and at least one weighted input bias.

21. A system or method for measuring a composition in the blood fluid according to claim 19, as dependent on claim 10, where the output value for the output node is a summation of weighted normalized hidden node output values and at least one weighted output bias.

22. A system or method for measuring a composition in the blood fluid according to claim 19, as dependent on claim 11, where the adjustments to the weightings of each link between each output bias and an output node is calculated with reference to the output gradient error.

23. A system or method for measuring a composition in the blood fluid according to claim 19, as dependent on claim 12, where each link weighting is calculated according to the following formula:

Δ

who_0k=η

·

δ

_k

where;

η

is the learning rate.

δ

_k is the output gradient error.

24. A system or method for measuring a composition in the blood fluid according to claim 23, where the adjustment to be made to the output value for the output node (neto_k) is determined by the following equation:

25. A system or method for measuring a composition in the blood fluid according to any preceding claim, where the at least one neural network comprises a first neural network and a second neural network, the first neural network configured so as to pre-process the plurality of measurements before passing the pre-processed measurements to the second neural network for determination of an overall measurement of the composition.

26. A system or method for measuring a composition in the blood fluid according to claim 25, where the first and second neural networks implement back propagation algorithms.

27. A system or method for measuring a composition in the blood fluid according to claim 26 where the first and second neural networks implement the same back propagation algorithm.

28. A system or method for measuring a composition in the blood fluid according to any one of claims 6 to 27, where the at least one neural network is trained until one of the following occurs:

the mean square error per training set is within a predetermined range;

the synaptic weights stabilise;

the bias level stabilises;

the mean square error of the system is within a predetermined range;

the mean square error over the entire training set is within a predetermined range;

a predetermined number of training iterations have been performed.

29. A system or method for measuring a composition in the blood fluid according to claim 28, where the at least one neural network is trained until the global mean square error of the system is less than 0.0008.

30. A system or method for measuring a composition in the blood fluid according to any preceding claim, where after training of the at least one neural network, the neural networks are verified by comparing the results of the trained neural network against measurements of the substance obtained through invasive measuring techniques.

31. A system or method for measuring a composition in the blood fluid according to any of claim 2-30 , where the non-invasive measuring unit comprises a plurality of laser diodes each emitting light at a unique wavelength absorbable by the composition, the measurements taken by each laser diode forming the plurality of measurements.

32. A system or method for measuring a composition in the blood fluid according to claim 31, where the composition to be measured is blood glucose and the wavelength of the light emitted by each of the plurality of laser diodes falls within the range 1600 nm to 1800 nm.

33. A system or method for measuring a composition in the blood fluid according to any one of claims 2 to 30, where the non-invasive measuring unit comprises at least one laser diode able to emit light at varying wavelengths absorbable by the composition, the measurements taken by the at least one laser diode at each of these varying wavelengths forming the plurality of measurements.

34. A system or method for measuring a composition in the blood fluid according to any one of claims 30 to 32, where the non-invasive measuring unit further comprises a control laser diode which emits light at a wavelength not absorbable by the composition.

2. A system for measuring a composition of a blood fluid comprising:

a non-invasive measuring unit for measuring the composition; and

at least one neural network for processing a plurality of measurements taken by the non-invasive measuring unit to determine an overall measurement of the composition in the blood fluid, wherein a linear equation associated with each output node of the at least one neural network is determined from a controlled source prior to training the at least one neural network.

3. A method of measuring a composition in a blood fluid comprising:

Obtaining a plurality of measurements from a non-invasive measuring unit, and

processing the plurality of measurements by at least one neural network to determine an overall measurement of the composition in the blood fluid, wherein a linear equation associated with each output node of the at least one neural network is determined from a controlled source prior to training the at least one neural network.

35. A computer-readable medium having recorded thereon:

Means for receiving a plurality of measurements of a composition of a blood fluid, and

at least one neural network to process the plurality of measurements of the composition of the blood fluid,

such that an overall measurement of the composition in the blood fluid is determined, wherein a linear equation associated with each output node of the at least one neural network is determined from a controlled source prior to training the at least one neutral network.