High resolution SPAD array-based diffuse optical tomography facilitates longitudinal monitoring of osteosarcoma growth in mice

We present a free-space time-domain diffuse optical tomography (TD-DOT) system that integrates SPAD array detection with geometric calibration for accurate, non-invasive tumor imaging. By combining structured-light surface extraction with calibration of source positions and detector responses, the system enables precise modeling of photon transport in air. Phantom studies demonstrate improved reconstruction accuracy across diverse shapes, while longitudinal in vivo imaging of mice with dorsal tumor reveals consistent changes in tumor volume and optical properties. These results demonstrate that our system enables high-quality, quantitative monitoring of tumor progression, underscoring its utility in preclinical research.