Gated Diffuse Optical Tomography for Deep Tissue Imaging
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Solution Overview
Problem
Existing deep tissue optical imaging techniques face challenges in achieving high image reconstruction quality, resolution, and fast data acquisition due to hardware complexity, increased computational complexity, and limited spatial diversity in measurements, particularly in ballistic and diffuse optical tomography (DOT) and time-of-flight DOT (ToF-DOT) systems.
Innovation Solution
The gated DOT (GDOT) system uses an array of pulsed light sources and detectors with time-gating functionality to measure photon intensity within a specific time window, eliminating the need for complex TCSPC hardware, allowing for dense source-detector pairs and improved spatial resolution, and employs Monte Carlo algorithms for image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ballistic imaging techniques are used to reduce light scattering, then image resolution is improved, but the number of detectable photons decreases exponentially with depth
Solution Approach 1:
The patent converts the harmful effect of light scattering into a beneficial tool by using time-gating to selectively detect photons based on their time-of-flight. Scattered photons, which arrive later than ballistic photons, are used to provide information about deeper tissue structures that would be inaccessible to pure ballistic imaging. This allows the system to image beyond 50 MFPs while maintaining resolution.
2Measurement precision
If time-of-flight DOT is used to improve reconstruction quality, then image resolution is improved, but hardware complexity increases significantly
Solution Approach 1:
The patent extracts only the essential time-gating functionality from complex TCSPC hardware, implementing a simplified time-gating mechanism that retains the ability to measure photon time-of-flight while eliminating unnecessary hardware complexity. This extraction allows the system to achieve ToF-DOT reconstruction quality without the significant hardware overhead of traditional TCSPC systems.
Solution Approach 2:
The patent uses software-based time-gating that replicates the functionality of hardware TCSPC systems through computational methods. By copying the essential measurement capability in software rather than requiring complex hardware, the system achieves similar reconstruction quality with dramatically reduced hardware complexity.
3Measurement precision
If time series recording is used to obtain transient information, then reconstruction quality is improved, but computational complexity increases super-linearly
Solution Approach 1:
The patent extracts and processes only the essential transient information needed for reconstruction, rather than processing complete time series data. By taking out only the critical time-gated photon counts and discarding redundant temporal information, the system maintains reconstruction quality while reducing computational complexity from super-linear to linear scaling.
4Device complexity
If the number of source-detector pairs is reduced to simplify hardware, then device complexity is reduced, but spatial diversity in measurements is limited
Solution Approach 1:
The patent compensates for reduced spatial diversity by exploiting the temporal dimension through time-gating. Instead of relying solely on increased spatial sampling with more source-detector pairs, the system uses the time-of-flight dimension to extract additional independent measurements from each source-detector pair, thereby maintaining measurement diversity with fewer physical components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
GDOT achieves superior spatial resolution and deep imaging capabilities beyond 50 MFPs with reduced hardware complexity and faster reconstruction times compared to conventional DOT and ToF-DOT systems.
Implementation Method 1
light propagating (e.g., ballistic and diffuse photons) between each source-detector pair is recorded
Implementation Method 2
EM scattering remains a challenge for deep tissue optical imaging
Implementation Method 3
received photons are binned based on their time-of-travel and a one-dimensional time series is recorded for each source-detector pair
Implementation Method 4
a detector, including a photodetector array with a time-gating function, configured to collect a scattered light
Implementation Method 5
a processor configured to determine an image of the target based on the scattered light
Data Source
AI summary
A system for imaging a target embedded in a scattering media includes: one or more light sources that are pulsed lights at one or more wavelengths in a range of visible to near-infrared; a detector, including a photodetector array with a time-gating function, configured to collect a scattered light after a gate start time; and a processor configured to determine an image of the target based on the scattered light.