The present thesis focuses on the development of error reduction methods in simulation-guided hyperthermia (HT) treatments, in particular for head and neck (H&N) tumors. HT¬¬¬¬ therapy has gained increasing attention in the medical field due to its role in enhancing conventional cancer treatments such as radiotherapy and chemotherapy. By elevating the temperature of tumor tissues to 40-44 °C using non-ionizing microwave radiation, it increases the sensitivity of cancer cells to radiation and improves drug delivery without introducing additional toxicity. The benefits of HT have been well-demonstrated across various tumor sites, including cervix, breast, head and neck, skin, bladder, and esophagus. For sub-superficial and deep-seated tumors, phased-array antenna systems are used to optimize the Specific Absorption Rate (SAR) within the tumor target, while minimizing the risk of hotspots in the surrounding healthy tissues.