Comparison between a time-domain and a frequency-domain system for optical tomography

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Optical Physics

Background:

• Medical optical tomography (MOT) is an emerging imaging modality.
• Accurate phase and amplitude data are crucial for reconstructing images in MOT.
• Comparing different MOT system designs is essential for advancing the technology.

Purpose of the Study:

• To compare the data quality of two MOT systems: a 32-channel time-domain (TD) system from UCL and a 16-channel frequency-domain (FD) system from HUT.
• To evaluate the impact of data quality on reconstructed image quality using quantitative criteria.

Main Methods:

• Collected phase and amplitude data from homogeneous and inhomogeneous phantoms using both HUT (FD) and UCL (TD) systems.
• Reconstructed images of scattering and absorption using a finite-element method (diffusion equation).
• Assessed data quality through mean root-mean-square (rms) errors and reproducibility, and image quality via contrast.

Main Results:

• The HUT system demonstrated lower mean rms errors (3.4% amplitude, 0.51° phase) compared to the UCL system (6.0% amplitude, 0.46° phase).
• The HUT system exhibited better amplitude reproducibility (0.4%) than the UCL system (4%), while phase reproducibility was similar (0.08°).
• Images reconstructed from HUT data generally showed higher contrast than those from UCL data.

Conclusions:

• The frequency-domain system from HUT provided higher quality amplitude and phase data compared to the time-domain system from UCL.
• The superior data quality from the HUT system led to improved image reconstruction quality, evidenced by higher contrast.
• These findings suggest the advantages of frequency-domain systems for medical optical tomography applications.