Thermal Evaluation of Multi-Antenna Systems Proposed to Treat Bone Tumors: Finite Element Analysis

Abstract

Microwave ablation is commonly used in soft tissue tumors, but its application in bone tumors has been barely analyzed. Antennas to treat bone tissue (~3 cm2), has been lately designed. Bone tumors at pathological stage T1 can reach 8 cm wide. An antenna cannot cover it; therefore, our goal is to evaluate the thermal performance of multi-antenna arrays. Linear, triangular, and square configurations of double slot (DS) and monopole (MTM) antennas were evaluated. A parametric study (finite element method), with variations in distance between antennas (ad) and bone thickness (bt) was implemented. Array feasibility was evaluated by SWR, ablated tissue volume, etc. The linear configuration with DS and MTM antennas showed SWR ≤ 1.6 for ad = 1 mm–15 mm and bt = 20 mm–40 mm, and ad = 10 mm–15 mm and bt = 25 mm–40 mm, respectively; the triangular showed SWR ≤ 1.5 for ad = 5 mm–15 mm and bt = 20 mm–40 mm and ad = 10 mm–15 mm and bt = 25 mm–40 mm. The square configuration (DS) generated SWR ≤ 1.5 for ad = 5 mm–20 mm and bt = 20 mm–40 mm, and the MTM, SWR ≤ 1.5 with ad = 10 mm and bt = 25 mm–40 mm. Ablated tissue was 4.65 cm3–10.46 cm3 after 5 min. According to treatment time and array configuration, maximum temperature and ablated tissue is modified. Bone tumors >3 cm3 can be treated by these antenna-arrays.

Keywords

• microwave ablation
• bone tumors
• thermal ablation
• antenna array
• FEM modeling