The potential of constrained SAR focusing for hyperthermia treatment planning: analysis for the head & neck region.

Clinical trials have shown that hyperthermia is a potent adjuvant to conventional cancer treatments, but the temperatures currently achieved in the clinic are still suboptimal. Hyperthermia treatment planning simulations have potential to improve the heating prole of phased-array applicators. An important open challenge is the development of an eective optimization procedure that enables uniform heating of the target region while keeping temperature below a threshold in healthy tissues. In this work, we analyzed the eectiveness and eciency of a recently proposed optimization approach, i.e., focusing via constrained power optimization (FOCO), using 3D simulations of twelve clinical patient specic models. FOCO performance was compared against a clinically used particle swarm based optimization approach. Evaluation metrics were target coverage at the 25% iso-SAR level, target hotspot quotient, median target temperature (T50) and computational requirements. Our results show that, on average, constrained power focusing performs slightly better than the clinical benchmark (△T50 = +0.05C), but outperforms this clinical benchmark for large target volumes (>40 cm3, △T50 = +0.39C). In addition, the results are achieved faster (-44%) and are repeatable because the approach is formulated as a convex optimization problem.