Brain functional imaging at small source-detector distances based on fast-gated single-photon avalanche diodes

Lorenzo Spinelli; Davide Contini; Rinaldo Cubeddu; Antonio Pifferi; Alessandro Torricelli; Fabrizio Martelli; Giovanni Zaccanti; Alberto Tosi; Alberto Dalla Mora; Franco Zappa; Sergio Cova

doi:10.1117/12.808245

23 February 2009 Brain functional imaging at small source-detector distances based on fast-gated single-photon avalanche diodes

Lorenzo Spinelli, Davide Contini, Rinaldo Cubeddu, Antonio Pifferi, Alessandro Torricelli, Fabrizio Martelli, Giovanni Zaccanti, Alberto Tosi, Alberto Dalla Mora, Franco Zappa, Sergio Cova

Author Affiliations +

Proceedings Volume 7161, Photonic Therapeutics and Diagnostics V; 71613B (2009) https://doi.org/10.1117/12.808245
Event: SPIE BiOS, 2009, San Jose, California, United States

Abstract

In this work we focused on time-resolved measurements in diffusive media performed at small (few millimeters) source-detector distances in reflectance geometry. This configuration has been predicted to have better contrast, better spatial resolution, and lower noise than the typical measurements performed at few centimeters. In our instrumental set-up we exploited a fast-gating (rise-time < 400 ps) front-end electronics enabling a silicon Single- Photon Avalanche Diode (SPAD) for time-correlated single-photon counting. By means of this detector, we can acquire "late" photons of the diffused light collected 2 mm apart from the injection point. This is possible because the fast gated SPAD rejects the huge amount of "early" photons which otherwise would saturate the detection electronic chain. The time resolution of the set-up is 100 ps. The instrument has been validated on both homogeneous and inhomogeneous (high absorbing inclusion at different depths inside) tissue phantoms with different optical properties. We obtained diffused time-resolved curves with dynamic ranges of about 107. Moreover, we demonstrated good agreement between the measured time-resolved contrasts and those calculated by Monte Carlo numerical simulations.

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Lorenzo Spinelli, Davide Contini, Rinaldo Cubeddu, Antonio Pifferi, Alessandro Torricelli, Fabrizio Martelli, Giovanni Zaccanti, Alberto Tosi, Alberto Dalla Mora, Franco Zappa, and Sergio Cova "Brain functional imaging at small source-detector distances based on fast-gated single-photon avalanche diodes", Proc. SPIE 7161, Photonic Therapeutics and Diagnostics V, 71613B (23 February 2009); https://doi.org/10.1117/12.808245

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