This thesis focuses on the development of a compact and cost-effective photoacoustic computed tomography (PACT) system for early detection of breast cancer. Traditional PACT systems are bulky and time-consuming, limiting their practical application. An experimental study was conducted to find a measurement setup for PACT that achieves high performance, low cost and a high degree of portability that would be easily transportable. The research investigated different instrument configurations and used an optomechanical ultrasound sensor (OMUS) that was developed using silicon photonic microchip technology. This sensor provides high sensitivity (NEP 1.3 mPa Hz−1/2), wide bandwidth (3 – 30 MHz), and small size (the sensing element is a membrane whose diameter is 20 μm), making it well-suited for use in a compact Photoacoustic Computed Tomography (PACT) system. The traditional laser light source was replaced with a smaller and more handheld LED to further reduce the footprint of the system. A major challenge was to acquire a photoacoustic signal from an object that absorbs light with an optical energy hundreds of times lower than that of the standard laser light source. The thesis provides an overview of the theoretical foundations of photoacoustic imaging, including a discussion of the photoacoustic effect and existing PACT systems. A comparison between two ultrasound detection platforms, the OMUS and a commercial linear probe, is presented in detail. Additionally, a study to evaluate the feasibility of achieving photoacoustic images using LED as light sources is presented. The thesis concludes with a discussion of the strengths and limitations of each setup used and future steps to develop a compact system that can distinguish between oxygenated and deoxygenated blood for potential tumor detection.
The sound of light: Sviluppo di un sistema di tomografia computerizzata fotoacustica compatto ed economico per l’imaging del cancro al seno. Questo lavoro di tesi si concentra sullo sviluppo di un sistema di tomografia computerizzata fotoacustica (PACT) compatto ed economico per la diagnosi precoce del cancro al seno. I sistemi PACT tradizionali sono ingombranti e richiedono molto tempo, il che ne limita l'applicazione pratica. È stato condotto uno studio sperimentale per trovare una configurazione di misura per la PACT che raggiungesse alte prestazioni, bassi costi e che fosse facilmente trasportabile. La ricerca ha esaminato diverse configurazioni di strumenti e ha utilizzato un sensore microchip a ultrasuoni opto meccanico (OMUS) sviluppato utilizzando la tecnologia dei dispositivi fotonici in silicio. Questo sensore offre un'elevata sensibilità (NEP 1.3 mPa Hz-1/2), un'ampia larghezza di banda (3 - 30 MHz) e dimensioni ridotte (l’elemento sensibile è una membrana il cui diametro è pari a 20 μm), che lo rendono adatto all'uso in un sistema compatto di tomografia computerizzata fotoacustica (PACT). La tradizionale sorgente di luce laser è stata sostituita da un dispositivo LED più piccolo e maneggevole per ridurre ulteriormente l'ingombro del sistema. Una sfida importante è stata quella di acquisire un segnale fotoacustico da un oggetto che assorbe la luce avente un'energia ottica cento volte inferiore a quella della sorgente di luce laser standard. La tesi fornisce una panoramica delle basi teoriche dell’imaging fotoacustico, compresa una discussione sull'effetto fotoacustico e sui sistemi PACT esistenti. Viene presentato in dettaglio un confronto tra due piattaforme di rivelazione degli ultrasuoni, ovvero l’OMUS e una sonda lineare ecografica commerciale. Inoltre, viene presentato uno studio per esaminare la possibilità di ottenere immagini fotoacustiche utilizzando i LED come sorgenti luminose. La tesi si conclude con una discussione dei punti di forza e dei limiti di ciascuna configurazione utilizzata e dei passi futuri per sviluppare un sistema compatto in grado di distinguere tra sangue ossigenato e deossigenato per la potenziale individuazione di tumori.
The Sound of Light: Development of a compact and Cost - Effective Photoacoustic Computed Tomography System for Breast Cancer Imaging
BASSI, IRENE
2021/2022
Abstract
This thesis focuses on the development of a compact and cost-effective photoacoustic computed tomography (PACT) system for early detection of breast cancer. Traditional PACT systems are bulky and time-consuming, limiting their practical application. An experimental study was conducted to find a measurement setup for PACT that achieves high performance, low cost and a high degree of portability that would be easily transportable. The research investigated different instrument configurations and used an optomechanical ultrasound sensor (OMUS) that was developed using silicon photonic microchip technology. This sensor provides high sensitivity (NEP 1.3 mPa Hz−1/2), wide bandwidth (3 – 30 MHz), and small size (the sensing element is a membrane whose diameter is 20 μm), making it well-suited for use in a compact Photoacoustic Computed Tomography (PACT) system. The traditional laser light source was replaced with a smaller and more handheld LED to further reduce the footprint of the system. A major challenge was to acquire a photoacoustic signal from an object that absorbs light with an optical energy hundreds of times lower than that of the standard laser light source. The thesis provides an overview of the theoretical foundations of photoacoustic imaging, including a discussion of the photoacoustic effect and existing PACT systems. A comparison between two ultrasound detection platforms, the OMUS and a commercial linear probe, is presented in detail. Additionally, a study to evaluate the feasibility of achieving photoacoustic images using LED as light sources is presented. The thesis concludes with a discussion of the strengths and limitations of each setup used and future steps to develop a compact system that can distinguish between oxygenated and deoxygenated blood for potential tumor detection.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/15855