Optical Tomography Early Photon Detection via Pulsed Illumination
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Solution Overview
Problem
Current optical tomography techniques face limitations in achieving high spatial resolution due to photon scattering in biological tissues, which restricts the ability to accurately map fluorescence targeted biological molecular concentration distributions.
Innovation Solution
The method enhances early photon detection by correlating the pulsing stimulus light with the detector's dead-time, allowing for higher power illumination and increased capture of early-arriving photons, which take a shorter path through the tissue, thereby improving spatial resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher power light sources are used to increase photon capture, then sensitivity improves, but detector saturation occurs reducing measurement precision
Solution Approach 1:
The patent applies periodic pulsed illumination at a repetition frequency where the pulse period exceeds the detector dead-time. This temporal structuring allows the detector to recover between pulses, preventing saturation while capturing photons from each pulse. The periodic nature synchronizes illumination with detector readiness cycles, enabling higher average power operation without losing measurement precision.
2Measurement precision
If pulsed illumination is used to improve spatial resolution through early photon detection, then spatial resolution improves, but photon capture rate decreases due to detector dead-time
Solution Approach 1:
The patent employs excessive illumination power relative to conventional approaches, deliberately overdriving the detector during the active detection window. By using pulse periods longer than dead-time, the system compensates for the lost photons during dead-time periods through increased photon flux during active periods. This partial action approach captures sufficient early photons for high spatial resolution while maintaining adequate overall capture rate.
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
This approach significantly enhances the detection of early-arriving photons, achieving orders-of-magnitude better sensitivity and spatial resolution for 3D molecular imaging, enabling more precise mapping of biological molecule concentrations and improving clinical applications such as cancer staging and drug delivery analysis.
Implementation Method 1
generating fluorescence data of fluorophores in tissue
Implementation Method 2
detected photon events are time-stamped through time-correlated single photon counting
Data Source
AI summary
A system and method for optical tomography including illuminating an object with pulsing stimulus light and pulsing the stimulus light at a repetition frequency having a pulse period that is greater than a dead-time of a detector. Coordinating the pulse with the dead-time of the detector allows for higher powered light source and improves early photon detection.