研究目的
To address the issues of low-cost, compact size and high integration capabilities in time-resolved diffuse optical spectroscopy (TR-DOS) systems for medical imaging applications.
研究成果
The TR-DOS prototype using low cost, compact, custom-designed free-running (FR) single-photon avalanche diode (SPAD) detectors in standard silicon 130 nm CMOS technology was successfully used to perform distribution of time of flight (DToF) histograms in reflectance geometry for phantoms that have optical properties (OP) in the range of human tissues. The prototype demonstrated good performance and can be used for tissue optics applications.
研究不足
The long time for data acquisition and the modest dynamic range (one order of magnitude) for DToF curves are limitations in the use of this prototype for some tissue optics applications such as functional brain imaging.
1:Experimental Design and Method Selection
Developed free-running (FR) single-photon avalanche diodes (SPADs) using 130 nm silicon complementary metal-oxide-semiconductor (CMOS) technology for a TR-DOS prototype. The prototype was validated using assessments from two known protocols for evaluating TR-DOS systems for tissue optics applications.
2:Sample Selection and Data Sources
Used two picosecond pulsed diode laser sources at wavelengths of 685 and 830 nm to illuminate phantoms with optical properties similar to human tissues.
3:List of Experimental Equipment and Materials
Custom-designed FR CMOS SPAD detectors, picosecond pulsed diode laser sources, multi-mode optical fiber, external pulse generator, optical power meter, pulse pattern generator, neutral-density (ND) filters, optical bandpass filter, Teledyne LeCroy oscilloscope.
4:Experimental Procedures and Operational Workflow
Measured the power of the light from the fiber, differential non-linearity (DNL), and the total Instrument Response Function of the setup (IRFTotal). Prepared homogeneous solid cylindrical phantoms with known optical properties for accuracy and linearity assessments.
5:Data Analysis Methods
Developed an iterative inverse problem solver to preprocess the raw data (DToF histograms) and retrieve the optical properties of the measured phantoms based on MCXLAB capabilities. Used a best-fitting model based on the Levenberg-Marquardt method for analysis.
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