A spread spectrum approach to time-domain near-infrared diffuse optical imaging using inexpensive optical transceiver modules

Abstract

We introduce a compact time-domain system for near-infrared spectroscopy using a spread spectrum technique. The proof-of-concept single channel instrument utilises a low-cost commercially available optical transceiver module as a light source, controlled by a Kintex 7 field programmable gate array (FPGA). The FPGA modulates the optical transceiver with maximum-length sequences at line rates up to 10Gb/s, allowing us to achieve an instrument response function with full width at half maximum under 600ps. The instrument is characterised through a set of detailed phantom measurements as well as proof-of-concept in vivo measurements, demonstrating performance comparable with conventional pulsed time-domain near-infrared spectroscopy systems.

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

“…Very recently, Konstantinos et al [3] developed a single-channel TD-NIRS system using a spread spectrum technique for TOF measurements. As a light source, the system incorporates a low-cost commercially available optical transceiver module, widely used in telecommunications applications.…”

“…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 2018, Papadimitriou et al [3] also described the drawbacks of TD-NIRS systems more in details (with modification), "TD-NIRS instruments used so far are bulky and expensive, and typically employ sensitive optoelectronics which are susceptible to vibrations. When solid state lasers are used, switching from one wavelength to another is slow about 10 s. When pulsed laser diodes are used, long warm-up time (about 60 min) is required to achieve a stability of pulse timing in the picosecond range.…”

“…Torricelli et al [2] continued the above description with expectations, "Recent advances in photonic technologies might allow to bridge the gap between TD-NIRS and CW-NIRS and potentially to overtake CW-NIRS." Also, Papadimitriou et al [3] expressed expectations for advanced TD-NIRS systems, describing that smaller and more robust instruments might lead to wider applications, for example in emergency medicine.In this article for TD-NIRS and imaging, we first review the theoretical background of TD-NIRS and provide an overview of TD-NIRS instruments. Then, we proceed to the advanced theories and methods of the TD-NIRS technique and review studies on the clinical applications of the TD-NIRS technique including TD diffuse optical tomography (TD-DOT) and TD fluorescence tomography (TD-FT).…”

“…Torricelli et al [2] continued the above description with expectations, "Recent advances in photonic technologies might allow to bridge the gap between TD-NIRS and CW-NIRS and potentially to overtake CW-NIRS." Also, Papadimitriou et al [3] expressed expectations for advanced TD-NIRS systems, describing that smaller and more robust instruments might lead to wider applications, for example in emergency medicine.…”