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Experimental Verification of the Thermal Properties of a Novel LDR Thermo-Brachytherapy Seed

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G Warrell

G Warrell1*, B Gautam2, D Shvydka3, M Subramanian4, T Ng5, E Parsai6, (1) University of Toledo, Toledo, Ohio, (2) The University of Toledo Medical Center, Toledo, OH, (3) University of Toledo, Toledo, Ohio, (4) Best Medical International, Inc, Springfield, VA, (5) University fo Toledo, Toledo, Ohio, (6) University of Toledo Medical Center, Toledo, OH

WE-A-108-4 Wednesday 8:00AM - 9:55AM Room: 108

Purpose
Hyperthermia is a highly effective adjuvant therapy when used with radiation therapy, as shown by multiple groups. A novel thermo-brachytherapy seed invented by our group combines both modalities by replacing the tungsten radiographic marker in a standard LDR brachytherapy seed with a piece of ferromagnetic alloy. This alloy has a Curie transition temperature of ~50 degrees-C, and acts as a self-regulating source of heat when exposed to an RF magnetic field. We present the results of experimental analysis of the thermal properties of the seed prototypes, and comparisons with computational analysis.

Methods
Behavior of the seeds in tissue was experimentally investigated by implanting ferromagnetic material and seed prototypes in pieces of ham, serving as a tissue-mimicking phantom. Induction heating of the seeds was performed with an industrial induction heater fitted with custom coils, and the temperature vs. time was obtained via an infrared camera and a fiber-optic thermometer. Computational analysis of the thermal properties of the self-regulating seeds was done via the finite element analysis partial differential equation solver COMSOL Multiphysics 4.3.

Results
Experimental work shows that hyperthermia can be induced in tissues over reasonable times with clinically-available magnetic field strengths. There is good correlation between experimental and computational investigations of the temperature rise and distribution for arrangements of thermo-brachytherapy prototypes in a tissue-mimicking phantom. The presented work will include quantitative and qualitative comparisons, as well as comparisons between the thermal and simulated radiation dose distributions of the thermo-brachytherapy seeds.

Conclusions
For the thermobrachytherapy seed under development with our group, we have demonstrated good agreement between theoretical modeling and measurements for temperature distributions using a tissue-mimicking phantom.

Acknowledgement
This research is supported with STTR NIH grant No. R41 CA153631-01A1.


Funding Support, Disclosures, and Conflict of Interest: This is supported through NIH grant No. R41 CA153631-01A1.

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