Dr. Annalisa Brodu Profile

Dr. Annalisa Brodu

at Single Quantum BV

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Publications (2)

SPIE Journal Paper | 3 April 2023 Open Access

Interstitial null-distance time-domain diffuse optical spectroscopy using a superconducting nanowire detector

Vamshi Damagatla, Pranav Lanka, Annalisa Brodu, Niels Noordzij, Jessie Qin-Dregely, Andrea Farina, Antonio Pifferi

JBO, Vol. 28, Issue 12, 121202, (April 2023) https://doi.org/10.1117/12.10.1117/1.JBO.28.12.121202

KEYWORDS: Photons, Simulations, Absorption, Diffuse optical spectroscopy, Light absorption, Scattering, Liquids, Superconductors, Signal detection, Nanowires

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SignificanceInterstitial 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.AimTo 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).ApproachIn 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.ResultsThis 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.ConclusionsUtilizing 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.

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Proceedings Article | 7 March 2023 Presentation + Paper

Superconducting nanowire detector for interstitial null-separation time-domain diffuse optical spectroscopy

Vamshi Damagatla, Pranav Lanka, Andrea Farina, Annalisa Brodu, Niels Noordzijc, Jessie Qin-Dregely, Antonio Pifferi

Proceedings Volume 12376, 123760F (2023) https://doi.org/10.1117/12.2649028

KEYWORDS: Photons, Monte Carlo methods, Absorption, Superconductors, Nanowires, Simulations, Diffuse optical spectroscopy, Silicon photomultipliers, Scattering

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