Handheld multispectral imager for quantitative skin assessment in low-resource settings

Area of Science:

• Biomedical optics
• Quantitative imaging technologies
• Spectroscopy

Background:

• Spatial frequency domain imaging (SFDI) quantifies tissue absorption and scattering.
• Calculating chromophore concentrations (e.g., hemoglobin, melanin) is crucial for diagnostics.
• Existing SFDI devices often rely on expensive, specialized components.

Purpose of the Study:

• To develop a low-cost, handheld SFDI device using consumer-grade RGB components.
• To extract additional spectral bands from RGB data without hardware modification.
• To validate the device's performance against established quantitative spectroscopy methods.

Main Methods:

• A compact RGB spectral imager was built using a color CMOS camera and LED projector.
• Additional spectral bands were extracted from RGB components ('cross-channels').
• Device characterization and performance evaluation were conducted using optical phantoms and in-vivo tissue, compared against spatial frequency domain spectroscopy (SFDS).

Main Results:

• Two effective cross-channel bands (520 nm and 556 nm) were extracted and characterized.
• The SFDI device demonstrated strong linear correlation with SFDS for optical properties (R² > 0.987).
• An alternative, low-cost characterization procedure yielded comparable accuracy to standard laboratory equipment.

Conclusions:

• Additional spectral bands can be extracted from commercial RGB systems for enhanced SFDI.
• The developed handheld device offers a low-cost, accurate alternative for quantitative tissue analysis.
• The findings support the use of accessible components for advanced biomedical imaging applications.