Characterization of a time-resolved non-contact scanning diffuse optical imaging system exploiting fast-gated single-photon avalanche diode detection

Abstract

We present a system for non-contact time-resolved diffuse reflectance imaging, based on small source-detector distance and high dynamic range measurements utilizing a fast-gated single-photon avalanche diode. The system is suitable for imaging of diffusive media without any contact with the sample and with a spatial resolution of about 1 cm at 1 cm depth. In order to objectively assess its performances, we adopted two standardized protocols developed for time-domain brain imagers. The related tests included the recording of the instrument response function of the setup and the responsivity of its detection system. Moreover, by using liquid turbid phantoms with absorbing inclusions, depth-dependent contrast and contrast-to-noise ratio as well as lateral spatial resolution were measured. To illustrate the potentialities of the novel approach, the characteristics of the non-contact system are discussed and compared to those of a fiber-based brain imager.

A Versatile Setup for Time-Resolved Functional Near Infrared Spectroscopy Based on Fast-Gated Single-Photon Avalanche Diode and on Four-Wave Mixing Laser

“…Different works based on FG-SPADs have been published, demonstrating experimentally that an improved spatial resolution, contrast and even chromophore quantification can be achieved using a gated detector [15][16][17]. However, to the best of our knowledge, the FG-SPAD detectors have never been adopted to demonstrate the improvement given by the use of short-SDD in fNIRS measurements.…”

Time-Domain Near-Infrared Spectroscopy and Imaging: A Review

“…Dalla Mora et al [59] also developed a system using fast-pulsed vertical cavity surface emitting lasers and fast-gated SPADs, both embedded into probes with SD distances of 5 mm and 30 mm, indicating the feasibility of application to wearable imaging instruments which should be compact, inexpensive, and quantitative. Furthermore, Di Sieno et al [60] modified the above system using an SC laser with an AOTF for the light source and fast-gated SPADs for the detector, aiming the application at non-contact measurements. They performed phantom experiments to evaluate the performances of the system and discussed the possibility of TD-DOT imaging with non-contact measurements.…”

“…1988 TD-NIRS system using a streak camera or TCSPC [34,36] 1999 2-wavelength multi-Ch TD-NIRS oximeter using pLDs and multi-anode PMTs [39] Commercial 1-Ch TD-NIRS system using TCSPC for research use: "TRS-10" [40] 1-wavelength 1-Ch TD optical mammography using a pLD and PMT-TCSPC [41] 64-channel TD-DOT system using pLDs and PMT-TCSPCs [45] 2000 32-channel TD-DOT system (MONSTIR) [49] 2003 TD-NIRS system using the spread spectrum technique and pseudo-random bit sequences [63] 2005 TD-NIRS system using time-gated ICCD [65] 16-channel TD-DOT system using pLDs and PMT-TCSPCs [50] 2009 Commercial 2-Ch TD-NIRS system using TCSPC for research use: "TRS-20" [43] 2011 48-Ch 3-wavelength TD-NIRS optical mammography [52] 2013 TD-DOT system incorporating SPADs into TCSPC [58] 2014 Commercial 2-Ch TD-NIRS system using MPPCs for medical use: "tNIRS-1" [55] MONSTIR II employing an SC laser with an AOTF for 4 wavelengths [51] 2016 TD-NIRS mammography for imaging the contents of water, lipid, collagen, oxy-Hb and deoxy-Hb using 7 wavelengths [54] Compact 2-wavelength TD-NIRS system and detector probe using SiPM [56,57] TD-NIRS system using an SC laser and SPADs for non-contact measurements [60] 2017 12-Ch TD-NIRS mammography with a hand-held probe [53] 2018 TD-DOT system using an SC laser and SPAD camera [62] Compact TD-NIRS system for measuring the contents of water, lipid, oxy-Hb, and deoxy-Hb using 6 wavelengths [68] Compact 1-Ch TD-NIRS system using telecommunication devices [3] Table 2. Chronology of major events in theories, methods and applications of TD-NIRS.…”

“…In this situation, slow but steady progresses in TD-NIRS systems over the conventional TD-NIRS techniques have recently shown the possibility and feasibility of solving the drawbacks. As described in Section 3.3, many new systems without using the PMTs have been developed such as the compact, low-power consuming and dual-channel or dual-wavelength TD-NIRS systems using the SiPMs (MPPCs) [55,56], the systems incorporating fast-gated SPADs [58,60,61], the systems based on a spread spectrum approach using laser diodes with pseudo-random-bit sequences [63,64], the systems using time-gated ICCD cameras [65,66], the system incorporating a low-cost commercially available optical transceiver module widely used in telecommunications [3], the system using a supercontinuum laser [67], and the system using state-of-the-art SPAD camera chips [62]. In particular, the SiPM (MPPC) that is a new photon counting semiconductor device may replace the conventional PMTs.…”

Fast localization method of an anomaly in tissue based on differential optical density

“…It's a simple, portable, accurate, and cost effective hematoma detection device for using in a variety of settings, including hospital emergency rooms and intensive care units. The exact placement of the source-detectors' is the key to detecting whether an anomaly exists in the target effectively [15]. The relationship between source-detectors distribution and detection results has always been a research hotspot in this field.…”