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Experimental and Computational Dosimetric Characterization of the Xoft AxxentTM Electronic Brachytherapy Source Within a Titanium Cervical Applicator


S Simiele

S Simiele*, T Pike, J Micka, L DeWerd, University of WI-Madison/ADCL, Madison, WI

WE-A-108-5 Wednesday 8:00AM - 9:55AM Room: 108

Purpose: To provide a dosimetric characterization of the Xoft Axxent™ source within a titanium cervical applicator using liquid water dosimetry and Monte Carlo simulation methods.

Methods: Absorbed dose to water measurements were performed using an annulus of Virtual Water™ (referred to as the Captains Wheel) that is mounted in a water phantom to allow measurements in liquid water. The Captains Wheel permits the precise placement of TLD-100 microcubes around the applicator using aluminum radial gauges of radii 1, 2, 3, and 4 cm. This geometry allows determination of the dose-rate constant, radial dose function, and azimuthal anisotropy. The air-kerma strength was measured using the Attix Free-Air Chamber at the UWADCL and well chamber measurements were completed using two Standard Imaging HDR1000 Plus well chambers. Measurements were performed using two Axxent™ sources calibrated at NIST. Monte Carlo simulations were also performed using MCNP5 based on specifications provided by the manufacturer to calculate the dose-rate constant, radial dose function, and polar anisotropy. MCNP5 was used to generate the source spectrum exiting the titanium applicator for comparison to the experimental results.

Results: The Monte Carlo dose-rate constant was 3.6% higher than the experimentally determined dose-rate constant. The radial dose value at 2 cm calculated for a 6 mm pullback distance was 3.5% lower when compared to the measured radial dose value at 2 cm. The azimuthal anisotropy measurements were normalized to the smallest TLD reading at a given distance, with a maximum anisotropy value of 1.27 at 2 cm.

Conclusion: TG-43 parameters were experimentally determined and compared to Monte Carlo simulations for the Axxent™ source within a titanium applicator.

Conflict of Interest: Xoft Inc. provided financial support, sources, and applicators.

Funding Support, Disclosures, and Conflict of Interest: Xoft Inc. provided financial support, sources, and applicators.

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