Behandlingsplanering för mikrovågshypertermi i huvud och halsregionen: En undersökning av patientmodellering och frekvensoptimering

Abstract

Hyperthermia is a complementary cancer treatment method in which tumour tissue is heated to approximately 40–44 ◦C. The method has proven effective in combination with conventional treatments such as radiotherapy and chemotherapy. Effective hyperthermia treatment requires careful and patient-specific treatment planning. The project aimed to evaluate the feasibility of creating a usable patient model from CT and MRI data and to investigate how the choice of frequency affects the heating efficiency in microwave hyperthermia in the head and neck region. The study is divided into two main parts: segmentation and construction of a digital patient model, as well as simulation and optimization. In the first part, a model was created by segmenting CT and MRI data. The segmentation was performed using the 3D Slicer software, combining manual, semi-manual and deep learning-based methods. This resulted in a digital model in which each segment was assigned material properties based on the IT’IS database. The project found the quality of this model sufficient for further simulation. In the second part, two existing patient models from ESHO were used. A numerical simulation was conducted in COMSOL to compute the electric fields generated by an applicator setup consisting of twelve self-grounded bow-tie antennas. Eleven frequencies between 250 and 750 MHz, as well as combinations of frequencies, were examined. Power deposition was then optimised toward a target region using the hot-to-Cold spot quotient as the cost function. Finally, the temperature distribution was calculated using Pennes’ bioheat equation. The results showed that lower single frequencies in the range of 250- 400 MHz generally yielded higher steady-state temperature distributions in the target volumes. This supports previous studies suggesting that lower frequencies can produce favourable results in the head region and that these findings may be generalizable to the neck. However, the number of case studies was too limited to draw a definite conclusion about optimal frequencies. Nevertheless, the results reinforce the theory that lower frequencies may yield good outcomes for hyperthermia treatment in the head and neck region.