FIBER OPTIC SENSORS FOR IN SITU MONITORING DURING THERMAL ABLATION OF TUMORS
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Date
2021-10-05
Authors
Jelbuldina, Madina
Journal Title
Journal ISSN
Volume Title
Publisher
Nazarbayev University School of Engineering and Digital Sciences
Abstract
High-temperature tumor ablation, or hyperthermia, is a minimally invasive therapy applied to treat benign and malignant tumors in different organs, most commonly for small and mid-size hepatic tumors.
The modern clinical standards determine 60 °C as a threshold for the almost immediate thermal coagulation of biological tissues. In order to perform the procedure effectively and avoid burning of healthy tissue, the limitations of ablation procedure have to be overcome. The limitations are related to incomplete ablation, the lack of the real time control of the procedure and inability to treat large size tumors. Real-time monitoring of the temperature dose within the target zone provides information about the amount of damaged tissue, hence allowing a clinician to regulate TA settings and to control procedural outcomes.
In this work two technological solutions is proposed to overcome the limitations of TA: (1) real-time detection of the temperature profiles in situ by means of fiber optic sensors that offer significant advantages over conventional thermometry techniques – thermocouples and imaging; (2) nanoparticles introduced in situ, which can mediate the thermal treatment by stabilizing and modifying the thermal, electrical, and optical properties of the tissue and increase the size of treatable tumors.
The overall goal of the thesis was to develop fiber optic based sensing for the multi-point real time temperature monitoring during thermal ablation.
This thesis presents a comparative study of sensing performance of 3 fiber optic sensing technologies, for the application of RF ablation. Temperature distribution during HIFU thermal treatment is performed ex vivo on a sample of breast fibroadenoma with the help of FBG sensors.
Next goal is to investigate the effect of nanoparticles on the outcomes of ex vivo TA with in-situ thermal profiling by means of fiber optic sensors. FBG based sensory system was implemented to investigate the effects of magnetite (Fe3O4) nanoparticles with 2 mg/mL and 5 mg/mL concentrations on RFA and MWA procedures. Results are presented in the forms of thermal maps, reporting the extension of lethal 60 °C isotherm by 20% for MWA, and by 60% for RFA.
The work presents results on thermal profiling by means of non-standard optical fibers, such as polymer fibers and fibers with enhanced scattering profile. Sensing performance of the chirped fiber Bragg grating fabricated on microstructured polymer optical fiber is investigated and validated during ex vivo RF ablation.
Finally, the thesis reports a novel setup based on MgO doped optical fibers that provides high resolution two dimensional temperature monitoring of thermal ablation. The setup utilizes specialty optical fibers with enhanced scattering profile (around 40 dB with respect to SMF) and allows for the OBR/OFDR interrogation of multiple fibers with a single scan. The proposed multiplexing configuration is validated in ex vivo laser ablation of liver phantom. Results of temperature measurements are two-dimensional thermal maps exhibiting high spatial resolution of 2.5 mm.
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Keywords
Type of access: Open Access, OBR/OFDR interrogation, fiber, Research Subject Categories::TECHNOLOGY
Citation
Jelbuldina, M. (2021). FIBER OPTIC SENSORS FOR IN SITU MONITORING DURING THERMAL ABLATION OF TUMORS (Unpublished master's thesis). Nazarbayev University, Nur-Sultan, Kazakhstan