Apparatus and method for imaging blood in a target region of tissue

Patent metadata

Field	Value
Publication number	US-11324424-B2
Application number	US-201816491959-A
Country	US
Kind code	B2
Filing date	Mar 9, 2018
Priority date	Mar 9, 2017
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

In some embodiments, an apparatus for imaging blood within a target region of tissue includes an imaging device configured to output image data associated with light received by the imaging device having a first and second spectral ranges, wherein the absorptivity by blood of light having the first spectral range is less than the absorptivity by blood of light having the second spectral range, and a controlling element configured to capture the image data associated with light received by the imaging device and to process the captured image data associated with light having the first spectral range and the captured image data associated with light having the second spectral range to generate compound image data associated with an amount of blood within the target region of tissue.

First claim

The invention claimed is:

1. Apparatus for imaging blood within a target region of tissue, comprising:
a light source configured to illuminate at least a portion of the target region of tissue with linearly polarised light where blood flow has been restricted, the linearly polarised light having at least a first spectral range and a second spectral range, wherein the absorptivity by blood of light having the first spectral range is less than the absorptivity by blood of light having the second spectral range;
an imaging system having an imaging sensor configured to capture an image of at least a portion of the target region of tissue illuminated by the linearly polarised light while blood flow is restored to the target region of tissue; and
a first linearly polarising filter arranged in front of the imaging sensor such that, in use, the first linearly polarising filter is disposed between the imaging sensor and the target region of tissue, wherein the first linearly polarising filter is arranged to block polarised illuminating light reflected by the target region of tissue.

2. The apparatus of claim 1 , wherein the first linearly polarising filter is arranged to polarise light in a plane which is orthogonal to the plane of polarisation of the linearly polarised light.

3. The apparatus of claim 1 , wherein the light source comprises a light emitter configured to emit unpolarised light and a second linearly polarising filter disposed in front of the light emitter.

4. The apparatus of claim 3 , wherein the light emitter comprises at least one light emitting diode.

5. The apparatus of claim 3 , wherein the second linearly polarising filter is arranged in a cross-polarised configuration with respect to the first linearly polarising filter such that light polarised by the second linearly polarising filter which remains polarised after being reflected by the target region of tissue is blocked by the first linearly polarising filter.

6. The apparatus of claim 5 , wherein the first and second linearly polarising filters are arranged such that the plane of polarisation of the first linearly polarising filter is at an angle of 90 degrees to the plane of polarisation of the second linearly polarising filter.

7. The apparatus of claim 1 , wherein the light source is configured to illuminate the portion of the target region of tissue with visible light.

8. The apparatus of claim 7 , wherein the first spectral range corresponds to a spectral range associated with red light and the second spectral range corresponds to a spectral range associated with green light.

9. The apparatus of claim 1 , wherein the light source comprises a diffuser arranged to provide diffused illuminating light.

10. The apparatus of claim 1 , wherein the apparatus comprises a smartphone.

11. A method of imaging blood within a target region of tissue, comprising the steps:
restricting blood flow to the target region of tissue;
after removing the restriction, illuminating the target region of tissue using linearly polarised light having at least a first spectral range and a second spectral range, such that the linearly polarised light is scattered and/or reflected by the target region of tissue, wherein the absorptivity by blood of light having the first spectral range is less than the absorptivity by blood of light having the second spectral range;
arranging an imaging system comprising an imaging sensor such that the imaging sensor is arranged to receive light scattered and/or reflected by the target region of tissue;
disposing a linearly polarising filter between the target region of tissue and the imaging sensor such that scattered light which has been depolarised by the target region of tissue is transmitted by the linearly polarising filter and reflected light which remains polarised is blocked by the linearly polarising filter; and
using the imaging system to capture at least one image of at least a portion of the target region of tissue using light which has been transmitted by the linearly polarising filter.

12. The method of claim 11 , wherein the linearly polarising filter is arranged such that the plane of polarisation of the linearly polarising filter is orthogonal to the plane of polarisation of the linearly polarised light.

13. The method of claim 12 , wherein the step of illuminating the target region of tissue using linearly polarised light comprises the step of using a light emitter configured to emit unpolarised light to emit light and disposing a second linearly polarising filter in front of the emitter to polarise the unpolarised light.

14. The method of claim 11 , wherein the target region of tissue is illuminated with visible light.

15. The method of claim 14 , wherein the first spectral range corresponds to a spectral range associated with red light and the second spectral range corresponds to a spectral range associated with green light.

16. The method of claim 11 , wherein the linearly polarised light is diffused light.

17. A method of imaging blood within a target region of tissue, comprising the steps:
restricting blood flow to the target region of tissue with an inflatable cuff;
illuminating the target region of tissue using linearly polarised light having at least a first spectral range and a second spectral range, such that the linearly polarised light is scattered and/or reflected by the target region of tissue, wherein the absorptivity by blood of light having the first spectral range is less than the absorptivity by blood of light having the second spectral range;
transmitting by a linearly polarising filter disposed between the target region of tissue and an imaging sensor scattered light which has been depolarised by the target region of tissue and blocking by the linearly polarising filter reflected light which remains polarised;
receiving with the imaging sensor light scattered and/or reflected by the target region of tissue; and
capturing at least one image of at least a portion of the target region of tissue using light which has been transmitted by the linearly polarising filter.

18. The method of claim 17 , wherein the linearly polarising filter is arranged such that the plane of polarisation of the linearly polarising filter is orthogonal to the plane of polarisation of the linearly polarised light.

19. The method of claim 18 , wherein the step of illuminating the target region of tissue using linearly polarised light comprises the step of using a light emitter configured to emit unpolarised light to emit light and disposing a second linearly polarising filter in front of the emitter to polarise the unpolarised light.

20. The method of claim 17 , wherein the target region of tissue is illuminated with visible light.

21. The method of claim 20 , wherein the first spectral range corresponds to a spectral range associated with red light and the second spectral range corresponds to a spectral range associated with green light.

22. The method of claim 17 , wherein the linearly polarised light is diffused light.

Assignees

• Smith & Nephew

Inventors

• Grubb Scott
• Hunt Allan Kenneth Frazer Grugeon
• Laitenberger Peter

Classifications

• A61B2562/046

  in a matrix array · CPC title

• A61B5/14558 Primary

  by polarisation · CPC title

• A61B5/14546

  for measuring analytes not otherwise provided for, e.g. ions, cytochromes · CPC title

• A61B2560/0431

  Portable apparatus, e.g. comprising a handle or case · CPC title

• A61B5/489

  Blood vessels · CPC title