title: Computer modelling of an impedance-controlled pulsing protocol for RF tumour ablation with a cooled electrode.
abstract: To develop computer models to mimic the impedance-controlled pulsing protocol implemented in radiofrequency (RF) generators used for clinical practice of radiofrequency ablation (RFA), and to assess the appropriateness of the models by comparing the computer results with those obtained in previous experimental studies.
  
  
  
  A 12-min RFA was modelled using a cooled electrode (17G, 3 cm tip) inserted in hepatic tissue. The short (transverse) diameter of the coagulation zone was assessed under in vivo (with blood perfusion (BP) and considering clamping) and ex vivo (at 21 °C) conditions. The computer results obtained by programming voltage pulses were compared with current pulses.
  
  
  
  The differences between voltage and current pulses were noticeable: using current instead of voltage allows larger coagulation zones to be created, due to the higher energy applied by current pulses. If voltage pulses are employed the model can accurately predict the number of roll-offs, although the waveform of the applied power is clearly not realistic. If current voltages are employed, the applied power waveform matches well with those reported experimentally, but there are significantly fewer roll-offs. Our computer results were overall into the ranges of experimental ones.
  
  
  
  The proposed models reproduce reasonably well the electrical-thermal performance and coagulation zone size obtained during an impedance-controlled pulsing protocol.
authors.affiliation: a Instituto Universitario de Matemática Pura y Aplicada, Universitat Politècnica de València , Spain.
authors.forename: Macarena
authors.initials: M
authors.lastname: Trujillo
authors.affiliation: b Food Technology Department , Universitat Politècnica de València , Spain.
authors.forename: Jose
authors.initials: J
authors.lastname: Bon
authors.affiliation: c Applied Mathematics Department , Universitat Politècnica de València , Spain.
authors.forename: María
authors.initials: M
authors.lastname: José Rivera
authors.affiliation: d Department of Surgery , Hospital del Mar , Barcelona , Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Burdío
authors.affiliation: e Biomedical Synergy, Department of Electronic Engineering , Universitat Politècnica de València , Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Berjano
mesh_terms: D055011:Ablation Techniques / Q000295:instrumentation*; D001769:Blood; D003198:Computer Simulation; D017097:Electric Impedance; D004566:Electrodes; D006801:Humans; D008099:Liver; D008962:Models, Theoretical; D009369:Neoplasms / Q000601:surgery*; D011846:Radio Waves; D013696:Temperature
keywords: Cooled electrode; finite element method; impedance control; pulsing protocol; radiofrequency ablation; thermal ablation; tumour ablation