title: Theoretical investigation into the feasibility to deposit RF energy centrally in the head-and-neck region.
abstract: OBJECTIVE
  To investigate the ability to deposit radiofrequency energy centrally in the neck as a function of antenna positions, number of antennas, and operating frequency.
  
  
  METHODS
  Power absorption (PA) distributions in a realistic model of the head-and-neck anatomy are calculated in which the head model is irradiated by an array of dipole antennas. The relative PA distributions corresponding to different setups are visualized and analyzed using the ratio of the average PA (aPA) in the target and neck region.
  
  
  RESULTS
  Both the PA distributions and aPA ratios indicate an optimal focusing ability of the setups (i.e., the ability to direct energy efficiently into the target region), between 400 and 600 MHz. In this frequency band, the focusing ability depends only moderately on the size of the neck. Finally, it is found that the focusing ability at 433 MHz is increased significantly by increasing the number of antenna elements.
  
  
  CONCLUSIONS
  The optimal frequency is found to be highly dependent on the size of the target volume; thus, a single optimum is hard to define. However, future clinical research will focus on 433 MHz based on the optimal range of frequencies, as found in this study.
authors.affiliation: Department of Radiation Oncology, Unit Hyperthermia, Erasmus Medical Center-Daniel den Hoed Cancer Center, NL-3008 AE Rotterdam, The Netherlands. M.Paulides@ErasmusMC.nl
authors.forename: Margarethus M
authors.initials: MM
authors.lastname: Paulides
authors.forename: Stefan H J A
authors.initials: SH
authors.lastname: Vossen
authors.forename: Adrianus P M
authors.initials: AP
authors.lastname: Zwamborn
authors.forename: Gerard C
authors.initials: GC
authors.lastname: van Rhoon
mesh_terms: D005240:Feasibility Studies; D006258:Head and Neck Neoplasms / Q000532:radiotherapy / Q000628:therapy*; D006801:Humans; D006979:Hyperthermia, Induced / Q000295:instrumentation / Q000379:methods*; D009333:Neck / Q000033:anatomy & histology; D000078702:Radiofrequency Therapy