A Taguchi-optimized agar phantom for temperature-based validation in electro-hyperthermia

Objective. This study aimed to develop and optimize an agar-based phantom using the Taguchi method for temperature-based validation of electro-hyperthermia systems in a quality assurance (QA) framework.Materials and methods. This study utilized the Taguchi method with an orthogonal array to design nine agar phantom formulations with varying concentrations of three factors: agar, sodium chloride (NaCl), and sodium azide (NaN₃). Heating was performed using the Oncotherm EHY-2000 RF hyperthermia device under six different power levels (25-100 W), with each stage lasting 5 min for a total duration of 30 min. Temperature changes were measured at a depth of 5 cm within the phantom using a type T thermocouple thermometer. A pork tissue model was used as the reference standard for comparison.Results.All phantom formulations exhibited a linear increase in temperature during the heating process. Analysis using Minitab software identified the optimal formulation, consisting of 5.0% agar, 0.1% NaCl, and 0.44% NaN₃, as producing a temperature profile most closely resembling that of the pork tissue model. Taguchi analysis indicated that agar concentration was the most significant factor influencing temperature variation. The interactions among the three formulation variables were weak, suggesting that each factor could be optimized independently.Significance.The agar phantom developed in this study features simple fabrication, reusability, and long-term storability, making it a practical tool for detecting abnormal heating in hyperthermia devices and enhancing treatment safety and accuracy. It is suited for routine QA of the Oncotherm electro-hyperthermia system.