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Development of a portable time-domain system for diffuse optical tomography of the newborn infant brain

Pérez Tirador, Pablo; (2021) Development of a portable time-domain system for diffuse optical tomography of the newborn infant brain. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Conditions such as hypoxic-ischaemic encephalopathy (HIE) and perinatal arterial ischaemic stroke (PAIS) are causes of lifelong neurodisability in a few hundred infants born in the UK each year. Early diagnosis and treatment are key, but no effective bedside detection and monitoring technology is available. Non-invasive, near-infrared techniques have been explored for several decades, but progress has been inhibited by the lack of a portable technology, and intensity measurements, which are strongly sensitive to uncertain and variable coupling of light sources and detector to the scalp. A technique known as time domain diffuse optical tomography (TD-DOT) uses measurements of photon flight times between sources and detectors placed on the scalp. Mean flight time is largely insensitive to the coupling and variation in mean flight time can reveal spatial variation in blood volume and oxygenation in regions of brain sampled by the measurements. While the cost, size and high power consumption of such technology have hitherto prevented development of a portable imaging system, recent advances in silicon technology are enabling portable and low-power TD-DOT devices to be built. A prototype TD-DOT system is proposed and demonstrated, with the long-term aim to design a portable system based on independent modules, each supporting a time-of-flight detector and a pulsed source. The operation is demonstrated of components that can be integrated in a portable system: silicon photodetectors, integrated circuit-based signal conditioning and time detection -- built using a combination of off-the-shelf components and reconfigurable hardware, standard computer interfaces, and data acquisition and calibration software. The only external elements are a PC and a pulsed laser source. This thesis describes the design process, and results are reported on the performance of a 2-channel system with online histogram generation, used for phantom imaging. Possible future development of the hardware is also discussed.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Development of a portable time-domain system for diffuse optical tomography of the newborn infant brain
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10122130
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