Characterization of a Time-Resolved Diffuse Optical Spectroscopy Prototype Using Low-Cost, Compact Single Photon...

Area of Science:

• Biomedical Optics
• Photonics
• Medical Imaging

Background:

• Time-resolved diffuse optical spectroscopy (TR-DOS) is vital for medical applications like brain, breast, and muscle imaging.
• Next-generation TR-DOS systems require cost-effectiveness, miniaturization, and efficient inverse modeling.

Purpose of the Study:

• To develop a low-cost, compact TR-DOS prototype using advanced silicon CMOS technology.
• To validate the prototype's performance for accurate tissue optical property measurements.

Main Methods:

• Developed free-running (FR) single-photon avalanche diodes (SPADs) using 130 nm silicon complementary metal-oxide-semiconductor (CMOS) technology.
• Integrated SPADs into a TR-DOS prototype and validated it using established instrumental performance and MEDPHOT protocols.
• Employed a Levenberg-Marquardt best-fitting model for optical property retrieval.

Main Results:

• The prototype demonstrated a sub-nanosecond instrument response function and low differential non-linearity.
• Acquired raw data from tissue-simulating phantoms with low optical power.
• Achieved accurate and linear retrieval of absolute optical properties for homogeneous phantoms.

Conclusions:

• Silicon CMOS-based SPAD detectors are suitable for building multichannel TR-DOS systems.
• The developed prototype enables potential real-time functional monitoring of human tissues like muscles, breasts, and newborn heads.
• Integration with a time-to-digital converter (TDC) will enhance real-time monitoring capabilities.