Program Information

Experimental and Monte Carlo Characterization of the 1 Cm CivaString ¹⁰³Pd Brachytherapy Source

J Reed

J Reed*¹, M Rivard² , J Micka¹ , W Culberson¹ , L DeWerd¹ , (1) University of Wisconsin Medical Radiation Research Center, Madison, WI, (2) Hopkinton, MA

Presentations

SU-F-19A-5 Sunday 4:00PM - 6:00PM Room: 19A

Purpose: To determine the in-air azimuthal anisotropy and in-water dose distribution for the 1 cm length of the CivaString ¹⁰³Pd brachytherapy source through measurements and Monte Carlo (MC) simulations. American Association of Physicists in Medicine Task Group No. 43 (TG-43) dosimetry parameters were also determined for this source.
Methods: The in-air azimuthal anisotropy of the source was measured with a NaI scintillation detector and simulated with the MCNP5 radiation transport code. Measured and simulated results were normalized to their respective mean values and compared. The TG-43 dose-rate constant, line-source radial dose function, and 2D anisotropy function for this source were determined from LiF:Mg,Ti thermoluminescent dosimeter (TLD) measurements and MC simulations. The impact of ¹⁰³Pd well-loading variability on the in-water dose distribution was investigated using MC simulations by comparing the dose distribution for a source model with four wells of equal strength to that for a source model with strengths increased by 1% for two of the four wells.
Results: NaI scintillation detector measurements and MC simulations of the in-air azimuthal anisotropy showed that ≥95% of the normalized data were within 1.2% of the mean value. TLD measurements and MC simulations of the TG-43 dose-rate constant, line-source radial dose function, and 2D anisotropy function agreed to within the experimental TLD uncertainties (k=2). MC simulations showed that a 1% variability in ¹⁰³Pd well-loading resulted in changes of <0.1%, <0.1%, and <0.3% in the TG-43 dose-rate constant, radial dose distribution, and polar dose distribution, respectively.
Conclusion: The CivaString source has a high degree of azimuthal symmetry as indicated by the NaI scintillation detector measurements and MC simulations of the in-air azimuthal anisotropy. TG-43 dosimetry parameters for this source were determined from TLD measurements and MC simulations. ¹⁰³Pd well-loading variability results in minimal variations in the in-water dose distribution according to MC simulations.

Funding Support, Disclosures, and Conflict of Interest: This work was partially supported by CivaTech Oncology, Inc. through an educational grant for Joshua Reed, John Micka, Wesley Culberson, and Larry DeWerd and through research support for Mark Rivard.


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