Dynamic time domain near-infrared optical tomography based on a SPAD camera.

Jingjing Jiang,Edoardo Charbon,Martin Wolf,Alexander Kalyanov,Aldo Di Costanzo Mata,Scott Lindner

doi:10.1364/boe.399387

Abstract

In many clinical applications it is relevant to observe dynamic changes in oxygenation. Therefore the ability of dynamic imaging with time domain (TD) near-infrared optical tomography (NIROT) will be important. But fast imaging is a challenge. The data acquisition of our handheld TD NIROT system based on single photon avalanche diode (SPAD) camera and 11 light sources was consequently accelerated. We tested the system on a diffusive medium simulating tissue with a moving object embedded. With 3D image reconstruction, the moving object was correctly located using only 0.2 s exposure time per source.

Highlights

Time domain (TD) near infrared optical tomography (NIROT) is a novel method that is able to quantitatively image the oxygenation of tissue
When near-infrared optical tomography (NIROT) is applied in e.g. early detection of neonatal brain injury and ischemic strokes [1] or functional brain imaging [2], the ability to detect dynamic changes of oxygenation is critical, because oxygenation may change quickly, and this may rapidly lead to adverse consequences
We estimate the signal-to-noise ratio (SNR) by taking the ratio of the mathematical expectation of signal and noise SNR = E[S]/E[N], where S is defined as the array of photon counts in the discernible range (30th to 80th time bin) and N is the array of dark photon counts

Summary

Introduction

Time domain (TD) near infrared optical tomography (NIROT) is a novel method that is able to quantitatively image the oxygenation of tissue. Reflection mode is commonly required In clinical applications, and the a priori information is limited To overcome all these problems, we developed a new handheld TD NIROT called Pioneer functioning in reflection mode. It utilizes a 32 × 32 SPAD camera measuring time of flight (ToF) for 12.5 ns with time resolution of 48.8 ps and 11 sources of pico-second laser radiation [8]. This system provides 2.88 × 106 measurement points and at the same time is featured with a compact design which allows it to be hand-held and bedside [5]. We have previously presented our system and showed successful reconstruction results of two objects embedded at different depths in a diffusive medium [5,9]

Methods

Results

Conclusion