Implementation of Thinned Array Synthesis in Hyperthermia Treatment Planning of 434 MHz Phased Array Breast Applicator Using Genetic Algorithm

Genetic algorithm-based array thinning technique is investigated in this paper to study the performance of our 18-element 434 MHz phased array breast applicator when driven by reduced number of active antennas. Selective power deposition ability was assessed for 18, 15, 12, and 9 active antennas on 25 patient models with varying characteristics. The average hotspot to target quotient of 18-, 15-, 12-, and 9-antenna excitation in 25 patient models was 1.18, 1.09, 1.09, and 1.13, respectively. The average temperature in 50% tumor volume for 18-, 15-, 12-, and 9-antenna excitation was 42.42 & DEG;C, 42.48 & DEG;C, 42.49 & DEG;C, and 42.48 & DEG;C, respectively. The temperature induced in tumor and healthy tissues is similar for varying number of active channels. However, the amount of power consumed was 25.2%, 53.9%, 97.9% higher for 15, 12, 9 active antennas compared to the filled array. Antenna array with 12 active elements was chosen as the optimal combination as it provided selective tumor heating with good tradeoff between number of channels and power consumption. The heating ability of the thinned array was assessed for 50% reduction in the number of active antennas on patient derived heterogeneous breast phantoms for five tumor target locations. The good agreement between simulated and measured thermal distributions demonstrate the selective heating ability of our phased array applicator for 50% reduction in hardware resources. The study outcome enables us to realize a cost-effective hyperthermia treatment delivery system.