Open Access
3 April 2023 Interstitial null-distance time-domain diffuse optical spectroscopy using a superconducting nanowire detector
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Abstract

Significance

Interstitial fiber-based spectroscopy is gaining interest for real-time in vivo optical biopsies, endoscopic interventions, and local monitoring of therapy. Different from other photonics approaches, time-domain diffuse optical spectroscopy (TD-DOS) can probe the tissue at a few cm distance from the fiber tip and disentangle absorption from the scattering properties. Nevertheless, the signal detected at a short distance from the source is strongly dominated by the photons arriving early at the detector, thus hampering the possibility of resolving late photons, which are rich in information about depth and absorption.

Aim

To fully benefit from the null-distance approach, a detector with an extremely high dynamic range is required to effectively collect the late photons; the goal of our paper is to test its feasibility to perform TD-DOS measurements at null source–detector separations (NSDS).

Approach

In particular, we demonstrate the use of a superconducting nanowire single photon detector (SNSPD) to perform TD-DOS at almost NSDS ( ≈ 150 μm ) by exploiting the high dynamic range and temporal resolution of the SNSPD to extract late arriving, deep-traveling photons from the burst of early photons.

Results

This approach was demonstrated both on Monte Carlo simulations and on phantom measurements, achieving an accuracy in the retrieval of the water spectrum of better than 15%, spanning almost two decades of absorption change in the 700- to 1100-nm range. Additionally, we show that, for interstitial measurements at null source–detector distance, the scattering coefficient has a negligible effect on late photons, easing the retrieval of the absorption coefficient.

Conclusions

Utilizing the SNSPD, broadband TD-DOS measurements were performed to successfully retrieve the absorption spectra of the liquid phantoms. Although the SNSPD has certain drawbacks for use in a clinical system, it is an emerging field with research progressing rapidly, and this makes the SNSPD a viable option and a good solution for future research in needle guided time-domain interstitial fiber spectroscopy.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Vamshi Damagatla, Pranav Lanka, Annalisa Brodu, Niels Noordzij, Jessie Qin-Dregely, Andrea Farina, and Antonio Pifferi "Interstitial null-distance time-domain diffuse optical spectroscopy using a superconducting nanowire detector," Journal of Biomedical Optics 28(12), 121202 (3 April 2023). https://doi.org/10.1117/1.JBO.28.12.121202
Received: 6 November 2022; Accepted: 9 January 2023; Published: 3 April 2023
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CITATIONS
Cited by 2 scholarly publications.
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KEYWORDS
Photons

Absorption

Simulations

Diffuse optical spectroscopy

Light absorption

Scattering

Liquids

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