RF hyperthermia array modelling; validation by means of measured EM-field distributions

Area of Science:

• Medical Physics
• Computational Electromagnetics

Background:

• Accurate hyperthermia treatment simulation is crucial for prospective treatment planning and patient-specific dosimetry.
• The accuracy depends on both the numerical simulation method and the description of the hyperthermia system.

Purpose of the Study:

• To investigate the accuracy of the numerical description of the AMC-4 waveguide phased array hyperthermia system using the Weak Form Conjugate Gradient FFT method.
• To compare simulated and measured electromagnetic (EM) field data for validation.

Main Methods:

• Analysis of an analytically solvable problem to determine numerical method accuracy.
• Comparison of simulated and measured EM-field amplitude and phase for the AMC-4 system.
• Investigated four setups varying bolus size and number of waveguides on a phantom.

Main Results:

• The Weak Formulation of the Conjugate Gradient FFT method accurately predicts EM-fields for the AMC-4 system, including effects of bolus size variations.
• Simulated and measured EM-field distributions revealed the planning system's insufficiency for quantitative Specific Absorption Rate (SAR) dosimetry in individual patients.

Conclusions:

• The numerical description and simulation method are capable of qualitative SAR dosimetry for retrospective analysis or identifying potential problem areas.
• Prospective applications include qualitative planning, determining optimal amplitude/phase settings, and evaluating new hyperthermia devices.