Development and testing of SAR-visualizing phantoms for quality control in RF hyperthermia

Area of Science:

• Medical Physics
• Biomedical Engineering
• Electromagnetics

Background:

• Accurate measurement of specific absorption rate (SAR) is crucial for radio frequency (RF) hyperthermia safety and efficacy.
• Existing methods for SAR assessment can be complex and time-consuming.
• A need exists for a practical and reliable phantom for visualizing SAR patterns.

Purpose of the Study:

• To develop and evaluate a new elliptical phantom prototype for visualizing SAR patterns.
• To assess the performance of light-emitting diodes (LEDs) as visualizing sensors for electric field strength.
• To demonstrate the utility of the phantom for quality control of RF hyperthermia systems.

Main Methods:

• Manufacture of solid phantom components using polyester or epoxy resin with carbon/aluminum powder admixtures.
• Evaluation of LED sensors for converting electric field strength to light output.
• Semi-quantitative assessment of SAR patterns using the phantom and power stepping method.
• Quantitative assessment using E-field sensor scans with fiber-coupled lamp sensors or dipole probes.

Main Results:

• The developed phantom successfully visualized SAR patterns in an RF hyperthermia system (BSD-2000).
• Iso-SAR distributions derived from the phantom visualization agreed well with E-field sensor scans.
• The technique demonstrated its capability for semi-quantitative SAR assessment.
• Comparisons with existing LED phantom techniques were performed.

Conclusions:

• The new phantom prototype provides a viable method for visualizing SAR patterns in RF hyperthermia.
• The developed technique facilitates periodic quality control of SAR patterns in hyperthermia systems.
• This approach offers a valuable tool for ensuring the safety and effectiveness of RF hyperthermia treatments.