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Toward a 2D Water-Equivalent Dosimetry Panel Using KCl:Eu2+

T Mazur

T Mazur1*, Z Xiao2 , J Driewer3 , Y Wang1 , H Li1 , (1) Washington University School of Medicine, St Louis, MO, (2) Rutgers Cancer Institute of New Jersey, St. Louis, MO, (3) University of Nebraska Medical Center, Omaha, NE


WE-AB-BRB-5 (Wednesday, July 15, 2015) 7:30 AM - 9:30 AM Room: Ballroom B

Purpose: KCl:Eu2+ storage phosphor shows promise for radiation therapy dosimetry. The purpose of this work is to investigate several important aspects of this material for potential commercial use.
Methods: KCl:Eu2+ chips were fabricated and a conformal coating using Parylene was applied. Material's dose response in a 6 MV beam was investigated using Monte-Carlo simulations. We attempted to micronize the materials using a spiral jet mill. As we did not have a water-free glovebox, we used commercially available non-hygroscopic BaFBr0.85I0.15:Eu2+ computed radiography material to test if a homogeneous panel can be made using micron-sized phosphors.
Results: Dosimeters remained intact and showed no change in PSL intensity after eight hrs of submersion in water. We then optically bleached the samples for reuse, irradiated and immersed for another 24 hrs. We observed marginal worsening of the PSL signal for both the soaked and un-soaked chips. By contrast, we were unable to measure PSL intensity of the un-coated pellets due to these pellets dissolving within minutes of being immersed in water. MC data indicate that the micron-sized KCl:Eu2+ is predicted to have a nearly water-equivalent response. KCl:Eu2+ particles with a median size of 3 microns can be produced using a jet mill, which could be reduced further if necessary. While the particles tend to agglomerate over time when stored in a desiccator, they still possess favorable d50’s and d99’s even after 100 minutes, providing an adequate time window for making a panel via tape casting. A panel cast using optimized methods exhibits nearly perfect particle arrangement.
Conclusions: Data shown here support ongoing efforts in fabricating a reusable, high resolution dosimetry panel in a water-free glovebox using micron-sized KCl:Eu2+ particles separated by water-equivalent polymers. The conformal coating thereafter will provide good humidity resistance.

Funding Support, Disclosures, and Conflict of Interest: HL is the founder of DoseImaging, LLC that is exclusively dedicated to commercializing this technology.

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