Theoretical modeling of RF ablation with internally cooled electrodes:
Comparative study of different thermal boundary conditions at the
electrode-tissue interface
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1.
Instituto Universitario de Matemática Pura y Aplicada, Universidad Politécnica de Valencia, Camino de Vera s/n. 46022, Valencia
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2.
Institute for Research and Innovation on Bioengineering, Universidad Politécnica de Valencia, Camino de Vera s/n. 46022, Valencia
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Received:
01 September 2008
Accepted:
29 June 2018
Published:
01 June 2009
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MSC :
Primary: 92C05, 92C10, 92C50; Secondary: 93A30.
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Previous studies on computer modeling of RF ablation with cooled
electrodes modeled the internal cooling circuit by setting surface
temperature at the coolant temperature (i.e., Dirichlet condition,
DC). Our objective was to compare the temperature profiles
computed from different thermal boundary conditions at the
electrode-tissue interface. We built an analytical one-dimensional
model based on a spherical electrode. Four cases were considered:
A) DC with uniform initial condition, B) DC with pre-cooling
period, C) Boundary condition based on Newton's cooling law (NC)
with uniform initial condition, and D) NC with a pre-cooling
period. The results showed that for a long time ($120$ s), the
profiles obtained with (Cases B and D) and without (Cases A and C)
considering pre-cooling are very similar. However, for shorter
times ($<30$ s), Cases A and C overestimated the temperature at
points away from the electrode-tissue interface. In the NC cases,
this overestimation was more evident for higher values of the
convective heat transfer coefficient ($h$). Finally, with NC, when
$h$ was increased the temperature profiles became more similar to
those with DC. The results suggest that theoretical modeling of RF
ablation with cooled electrodes should consider: 1) the modeling
of a pre-cooling period, especially if one is interested in the
thermal profiles registered at the beginning of RF application;
and 2) NC rather than DC, especially for low flow in the internal
circuit.
Citation: María J. Rivera, Juan A. López Molina, Macarena Trujillo, Enrique J. Berjano. Theoretical modeling of RF ablation with internally cooled electrodes:Comparative study of different thermal boundary conditions at theelectrode-tissue interface[J]. Mathematical Biosciences and Engineering, 2009, 6(3): 611-627. doi: 10.3934/mbe.2009.6.611
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Abstract
Previous studies on computer modeling of RF ablation with cooled
electrodes modeled the internal cooling circuit by setting surface
temperature at the coolant temperature (i.e., Dirichlet condition,
DC). Our objective was to compare the temperature profiles
computed from different thermal boundary conditions at the
electrode-tissue interface. We built an analytical one-dimensional
model based on a spherical electrode. Four cases were considered:
A) DC with uniform initial condition, B) DC with pre-cooling
period, C) Boundary condition based on Newton's cooling law (NC)
with uniform initial condition, and D) NC with a pre-cooling
period. The results showed that for a long time ($120$ s), the
profiles obtained with (Cases B and D) and without (Cases A and C)
considering pre-cooling are very similar. However, for shorter
times ($<30$ s), Cases A and C overestimated the temperature at
points away from the electrode-tissue interface. In the NC cases,
this overestimation was more evident for higher values of the
convective heat transfer coefficient ($h$). Finally, with NC, when
$h$ was increased the temperature profiles became more similar to
those with DC. The results suggest that theoretical modeling of RF
ablation with cooled electrodes should consider: 1) the modeling
of a pre-cooling period, especially if one is interested in the
thermal profiles registered at the beginning of RF application;
and 2) NC rather than DC, especially for low flow in the internal
circuit.
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