title: Body conformal antennas for superficial hyperthermia: the impact of bending contact flexible microstrip applicators on their electromagnetic behavior.
abstract: Hyperthermia is a powerful radiosensitizer for treatment of superficial tumors. This requires body conformal antennas with a power distribution as homogeneous as possible over the skin area. The contact flexible microstrip applicators (CFMA) operating at 434 MHz exist in several sizes, including the large size 3H and 5H. This paper investigates the behavior of the electromagnetic fields for the 3H and 5H CFMA in both flat and curved configurations, and the impact on performance parameters like the penetration depth (PD) and the effective heating depth (EHD). The underlying theory behind the electromagnetic behavior in curved situations is presented as well as numerical simulations of both flat and curved configurations. The results are compared to measurements of the electromagnetic field distributions in a cylindrical patient model. Due to their large size multimode solutions may exist, and our results confirm their existence. These multimode solutions affect both the power distribution and PD/EHD, with a dependence on applicator curvature. Therefore, the performance parameters like PD and EHD need to be carefully assessed when bending large size CFMA applicators to conform to the patient body. This conclusion also holds for other types of large size surface current applicators.
authors.affiliation: Department of Radiation Oncology, Academic Medical Center, Amsterdam 1105 AZ, The Netherlands. D.Correia@amc.nl
authors.forename: Davi
authors.initials: D
authors.lastname: Correia
authors.forename: H Petra
authors.initials: HP
authors.lastname: Kok
authors.forename: Martijn
authors.initials: M
authors.lastname: de Greef
authors.forename: Arjan
authors.initials: A
authors.lastname: Bel
authors.forename: Niek
authors.initials: N
authors.lastname: van Wieringen
authors.forename: Johannes
authors.initials: J
authors.lastname: Crezee
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004574:Electromagnetic Fields; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D006979:Hyperthermia, Induced / Q000295:instrumentation* / Q000379:methods*; D008839:Microelectrodes; D008954:Models, Biological; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013813:Therapy, Computer-Assisted / Q000379:methods*