Finite element simulation of Sigma 60 heating in the Utah phantom: computed and measured data compared

Abstract

An initial series of comparisons are made between finite element computations and laboratory measurements obtained during heterogeneous phantom heating with the Sigma 60 applicator. The phantom is a relatively complex, though still idealized, rendering of the pelvic area which has been used to study the deep heating characteristics of the Sigma 60 in this anatomy. Direct electric field measurements as well as inferred SAR through transient temperature analysis are plotted against computed results along 11 one-dimensional tracks through the phantom. Quantitative comparisons provided through the track-by-track analysis show generally good agreement between computation and measurement. The finite element method is found to predict well the jumps in the electric field when polarized perpendicularly to a muscle/fat interface. Visualizations of the complete three-dimensional distributions are also highlighted and correlate well with physical reasoning about the expected behaviour of the fields produced. Some discrepancies in the data persist and are discussed and analysed in depth. They underscore the difficulties that can arise in performing comparisons between measured and computed results and stress the need for careful and thorough investigations when attempting these types of model validation studies.

Key Words:

• Finite elements
• SAR modelling
• deep heating
• experimental verification
• phantom models