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Preliminary Results On New Optically Stimulated Luminescent Materials for Proton Therapy Dosimetry

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B Doull

B Doull1*, Y Zheng1,2 , E Yukihara3 , (1) Oklahoma State University, Stillwater, OK (2) Procure Proton Therapy Center, Oklahoma City, OK


SU-E-T-264 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: The objective of this work is to test the premise that luminescence materials with less under-response to proton beams can be identified by testing their dose response to low-LET radiation. The goal is to develop new Optically Stimulated Luminescence (OSL) materials with improved response for proton therapy dosimetry.

Methods: We first measured the dose response of new OSL materials, synthesized in our laboratory, to low-LET radiation (beta rays from a ⁹⁰Sr/⁹⁰Y source) and selected two materials having different OSL saturation characteristics and good dosimetric properties, namely MgB₄O₇:Ce,Li and MgO:Li. Commercial Al₂O₃:C was also used for comparison. These materials were then irradiated at several depths along a pristine proton beam. The luminescence responses of the materials, relative to the entrance response, were compared with the depth dose profile measured by a multiple-layer ion chamber.

Results: The OSL signals of MgB₄O₇:Ce,Li and MgO:Li were characterized for signal stability, dose response, and response to a clinical proton beam. The materials were also compared with the commercial Al₂O₃:C. The signals from both MgB₄O₇:Ce,Li and MgO:Li were relatively stable after a one day delay following irradiation. The low-LET dose response of the materials showed that, over the dose range investigated (up to ~800 Gy), MgB₄O₇:Ce,Li did not saturate, whereas MgO:Li and Al₂O₃:C saturated at doses of ~100 Gy. MgB₄O₇:Ce,Li showed less under-response to proton beams than MgO:Li and Al₂O₃:C.

Conclusion: In general the material with the highest saturation doses for low-LET radiation (MgB₄O₇:Ce,Li) showed the least under-response to proton beams, which suggests that it may be possible to develop better OSL materials for proton dosimetry if the dose response can be controlled during synthesis. Nevertheless, the degree in which the response to proton beams can be controlled remains to be determined.

Funding Support, Disclosures, and Conflict of Interest: The research is funded by the Oklahoma Center for the Advancement of Science and Technology (OCAST), project number HR12-055.

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