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Title:Numerical solving of inverse non-Fourier bioheat problem for use in dynamic thermography : doctoral dissertation
Authors:ID Horvat, Ivan Dominik (Author)
ID Iljaž, Jurij (Mentor) More about this mentor... New window
Files:.pdf DOK_Horvat_Ivan_Dominik_2026.pdf (3,30 MB)
MD5: EFD90FD0EFA113F4DDAEE6D466F6EC39
 
Language:English
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Infrared thermography is a non-invasive technique applied across industrial, environmental, and medical fields for detecting and interpreting surface temperature distributions. In medical diagnostics, dynamic infrared thermography can reveal underlying physiological processes such as altered metabolism and angiogenesis through subtle thermal anomalies, particularly in the use for early skin cancer diagnosis. However, conventional diagnostic methods remain subjective and prone to false alarms, while standard Fourier-based bioheat models fail to capture rapid transient thermal behavior in heterogeneous tissues. This doctoral research addresses these limitations by developing a numerical solver for solving direct and inverse problems, based on the dual-phase-lag non-Fourier bioheat model and a subdomain boundary element method, enabling accurate simulation of multilayer skin structures under dynamic thermal conditions. The direct problem analysis demonstrated that incorporating non-Fourier effects enhances the thermal contrast between healthy and tumor-affected tissues. A hybrid Levenberg-Marquardt optimization algorithm was implemented for solving the inverse problem, allowing the estimation of diagnostically critical parameters such as tumor diameter, thickness, blood perfusion rate, and thermal relaxation time from noisy surface temperature measurements. Results showed that tumor diameter and thermal relaxation time were the most stable and reliably estimated parameters, while blood perfusion rate and tumor thickness were highly sensitive to noise, especially for deeper lesions and increased model uncertainties. Furthermore, the study revealed that absolute temperature measurements provided more accurate inverse results than relative thermal contrast, and that non-Fourier effects notably delayed tumor thermal response, an insight crucial for optimizing dynamic thermography protocols. These contributions advance the understanding of bioheat transfer in living tissues, improve the accuracy and robustness of non-invasive diagnostic techniques, and lay the foundations for future clinical applications of dynamic infrared thermography.
Keywords:numerical modeling, non-Fourier bioheat transfer, boundary element method, inverse problem solving, optimization
Place of publishing:Maribor
Place of performance:Maribor
Publisher:[I. D. Horvat]
Year of publishing:2025
Number of pages:VIII, 136 str.
PID:20.500.12556/DKUM-92618 New window
UDC:517.956.27:519.612(043.3)
COBISS.SI-ID:267992579 New window
Publication date in DKUM:04.02.2026
Views:233
Downloads:40
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
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Licences

License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:25.04.2025

Secondary language

Language:Slovenian
Title:Numerično reševanje inverznega problema nefourierovega bioprenosa toplote za uporabo pri dinamični termografiji : doktorska disertacija
Abstract:Infrardeča termografija je neinvazivna tehnika, ki se uporablja na industrijskem, okoljskem in medicinskem področju za zaznavanje in interpretacijo porazdelitev površinskih temperatur. V medicinski diagnostiki lahko dinamična infrardeča termografija s pomočjo subtilnih toplotnih anomalij razkrije podlage fizioloških procesov, kot sta spremenjen metabolizem in angiogeneza, še posebej pri zgodnjem odkrivanju kožnega raka. Kljub temu pa konvencionalne diagnostične metode ostajajo subjektivne in nagnjene k napačnim diagnozam, standardni fourierjevi modeli bioprenosa toplote pa ne zajamejo hitrega prehodnega toplotnega odziva v heterogenih tkivih. Ta doktorska disertacija naslavlja te omejitve z razvojem numeričnega reševalnika za reševanje direktnih in inverznih problemov, ki temelji na nefourierjevem modelu bioprenosa toplote z dvojnim zamikom in podobmočni metodi robnih elementov, kar omogoča natančno simulacijo večplastnih kožnih struktur v dinamičnih toplotnih pogojih. Analiza direktnega problema je pokazala, da vključitev nefourierovih učinkov poveča toplotni kontrast med zdravim in tumorsko spremenjenim tkivom. Za reševanje inverznega problema je bil implementiran hibridni Levenberg-Marquardt optimizacijski algoritem, ki omogoča ocenjevanje diagnostično pomembnih parametrov, kot so premer tumorja, njegova debelina, hitrost perfuzije krvi in relaksacijski čas, na podlagi šumnih meritev površinske temperature. Rezultati so pokazali, da sta premer tumorja in relaksacijski čas najstabilnejša in najzanesljiveje ocenjena parametra, medtem ko sta hitrost perfuzije krvi in debelina tumorja močno občutljiva na šum, zlasti pri globljih spremembah in povečani negotovosti modela. Poleg tega je raziskava pokazala, da absolutne temperaturne meritve omogočajo natančnejše rezultate inverznega problema kot relativni toplotni kontrast ter da nefourierjevi učinki občutno zamaknejo toplotni odziv tumorja -- pomembno spoznanje za optimizacijo protokolov dinamične termografije. Ti prispevki poglabljajo razumevanje prenosa toplote v živih tkivih, izboljšujejo natančnost in zanesljivost neinvazivnih diagnostičnih tehnik ter postavljajo temelje za prihodnjo klinično uporabo dinamične infrardeče termografije.
Keywords:numerično modeliranje, dinamična termografija, nefourierov bioprenos toplote, metoda robnih elementov, reševanje inverznih problemov, optimizacija


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