High Performance Imaging System for Diffuse Optical Tomography and Associated Method of Use

• US 20080154126A1
• Filed: 12/21/2007
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Washington University In St Louis
• Original Assignee: Washington University In St Louis
• Inventors: Perry, Gavin, Zeff, Benjamin, Culver, Joseph
• Granted Patent: US 7,983,740 B2
• Time in Patent Office: Days
• US Class Current: 600/426
• CPC Class Codes: A61B 5/0042 for the brain
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence

Abstract

A high performance imaging system for diffuse optical tomography is disclosed. A dense grid utilizing sources, e.g., light emitting diodes (“LEDs”), that achieve high performance at high speed with a high dynamic range and low inter-channel crosstalk are complemented by a system of discrete, isolated receivers, e.g., avalanche photodiodes (“APDs”). The source channels have dedicated reconfigurable encoding control signals, and the detector channels have reconfigurable decoding, allowing maximum flexibility and optimal mixtures of frequency and time encoding and decoding. Each detector channel is analyzed by dedicated, isolated, high-bandwidth receiver circuitry so that no channel gain switching is necessary. The resulting improvements to DOT system performance, e.g., increased dynamic range and decreased crosstalk, enable higher density imaging arrays and provide significantly enhanced DOT image quality. A processor can be utilized to provide sophisticated three dimensional modeling as well as noise reduction.

Claims

1. An imaging system for diffuse optical tomography comprising:

a plurality of light sources that are each connected to a digital input power source;

a plurality of light conduits are connected to the plurality of light sources;

an optode grid that is attachable to a portion of a human subject, wherein the optode grid design is connected to the plurality of light conduits;

a plurality of discrete, isolated, light detectors that are operatively connected to the optode grid for instantaneously detecting light provided by the plurality of light sources after interacting with the human subject; and

a plurality of analog to digital converters for converting a plurality of individual signals from the plurality of discrete, isolated, light detectors into a plurality of digital signals.

2. The imaging system for diffuse optical tomography of claim 1, wherein the system operates with a high dynamic range of at least 10⁵, crosstalk as being at least less than 10⁻

5 and a frame rate as being greater than one (1) Hertz.

3. The imaging system for diffuse optical tomography of claim 1, wherein the system operates with a high dynamic range of at least 10⁷, crosstalk as being at least less than 10⁻

6 and a frame rate as being greater than ten (10) Hertz.

4. The imaging system for diffuse optical tomography of claim 1, wherein the plurality of light sources are multiplexed.

5. The imaging system for diffuse optical tomography of claim 1, wherein the digital input power source modulates at a high bandwidth of at least one megahertz.

6. The imaging system for diffuse optical tomography of claim 1, wherein the plurality of light sources includes a plurality of light emitting diodes.

7. The imaging system for diffuse optical tomography of claim 1, wherein the plurality of light sources is selected from the group consisting of laser diodes, super luminescent emitting diodes, solid state lasers, or other laser sources.

8. The imaging system for diffuse optical tomography of claim 1, wherein the plurality of light conduits includes a plurality of fiber optic cables.

9. The imaging system for diffuse optical tomography of claim 8, wherein at least one of the plurality of fiber optic cables is multi-furcated to receive multiplex light from a single source.

10. The imaging system for diffuse optical tomography of claim 1, wherein the digital input power source utilized in conjunction with a threshold voltage for each of the plurality of light sources operates to minimize crosstalk.

11. The imaging system for diffuse optical tomography of claim 1, wherein the plurality of discrete, isolated, light detectors includes avalanche photo diodes.

12. The imaging system for diffuse optical tomography of claim 1, wherein the plurality of discrete, isolated, light detectors is selected from the group consisting of photodiodes or photomultiplier tubes.

13. The imaging system for diffuse optical tomography of claim 1, wherein the optode grid is a molded component that is attachable to a portion of a human subject with straps.

14. The imaging system for diffuse optical tomography of claim 1, further comprising a processor that generates a model selected from the group consisting of a homogeneous model, a layered model, a sphere model, a hemisphere model, a cylindrically-shaped model, or an anatomically derived model with finite element analysis from the plurality of digital signals.

15. The imaging system for diffuse optical tomography of claim 14, wherein finite element analysis includes finite element, forward light modeling.

16. The imaging system for diffuse optical tomography of claim 1, further includes a processor that utilizes at least one noise reduction algorithm on the plurality of digital signals.

17. The imaging system for diffuse optical tomography of claim 16, wherein said at least one noise reduction algorithm includes linear regression covariance analysis with an increase in contrast-to-noise ratio.

18. The imaging system for diffuse optical tomography of claim 16, wherein the noise reduction algorithms includes independent component analysis.

19. An imaging system for diffuse optical tomography comprising:

a plurality of light emitting diodes that are each connected to a digital input power source that operates at high speed in a high dynamic range;

a plurality of fiber optic cables connected in a one-to-one relationship to the plurality of light emitting diodes;

an optode grid that is attachable to a portion of a human subject, wherein the optode grid design is connected to the plurality of light conduits;

a plurality of avalanche photo diodes that are operatively connected to the optode grid for detecting light provided by the plurality of light emitting diodes after interacting with the human subject; and

a plurality of analog to digital converters for converting a plurality of individual signals from the plurality of avalanche photo diodes into a plurality of digital signals.

20. A method for utilizing an imaging system for diffuse optical tomography comprising:

attaching an optode grid to a portion of a human subject, wherein the optode grid design is connected to the plurality of light conduits that are connected in a to a plurality of light sources that are electrically connected to a digital input power source;

utilizing a plurality of discrete, isolated, light detectors that are operatively connected to the optode grid for instantaneously detecting light provided by the plurality of light sources after interacting with the human subject; and

converting a plurality of individual signals from the plurality of discrete, isolated, light detectors into a plurality of digital signals with at least one analog to digital converter.

21. The method for utilizing an imaging system for diffuse optical tomography according to claim 20, further includes providing signals at a high speed in a high dynamic range with the digital input power source.

22. The method for utilizing an imaging system for diffuse optical tomography according to claim 20, wherein the plurality of light sources is selected from the group consisting of light emitting diodes, laser diodes, super luminescent emitting diodes, solid state lasers, or other laser sources, and the plurality of discrete, isolated, light detectors is selected from the group consisting of avalanche photo diodes, photodiodes or photomultiplier tubes.

23. The method for utilizing an imaging system for diffuse optical tomography according to claim 20, further includes generating a model selected from the group consisting of a homogeneous model, a layered model, a sphere model, a hemisphere model, a cylindrically-shaped model, or an anatomically derived model with finite element analysis with a processor from the plurality of digital signals.

24. The method for utilizing an imaging system for diffuse optical tomography according to claim 20, further includes utilizing at least one noise reduction algorithm with a processor on the plurality of digital signals, wherein the at least one noise reduction algorithm is selected from the group consisting of linear regression covariance analysis and independent component analysis.

25. The method for utilizing an imaging system for diffuse optical tomography according to claim 20, further includes utilizing filters positioned in front of the plurality of discrete, isolated, light detectors for detecting fluorescing agents in a human body.