Author: Mohammad Nazmul Alim, Regina DeWitt 👨🔬
Affiliation: Department of Physics, East Carolina University,, Department of Physics, East Carolina University 🌍
Purpose: This study quantifies the ability of Luxel (Al₂O₃:C) to measure radiation dose from a Moxtek X-ray source. Key aspects of OSL dosimetry, including OSL curves, dose response, depth dose, and beam profile, were investigated.
Methods: 6 mm diameter, 0.3 mm thick Luxel samples were irradiated using a Moxtek X-ray source (50 kV, 200 µA, calibrated at 100 mGy/s). Luminescence signals were captured using a PIXIS 1024 CCD camera in a darkroom illuminated by six red light lamps. Samples were stimulated with green LEDs (500-550 nm) after irradiation.
For OSL curves, the sample was irradiated for 5-100 s, followed by imaging over 40 s (10 images at 4 s intervals) and bleaching for 180 s. Dose response was measured after irradiation for 2–120 s, with images taken at 5 s exposure and bleaching between measurements. Depth dose curves were generated using stacked Luxel samples irradiated for 100 s. Beam parameters, including flatness and symmetry, were analyzed using Gafchromic EBT3 film and a non-uniform Luxel film created by embedding circular Luxel pieces on sticky paper.
Results: OSL signals declined sharply within 8 s, with steeper curves observed for longer irradiation times. The dose response curve was linear up to 12 Gy (120 s), with a minimum detectable dose of 200 mGy (2 s). The depth dose curve showed an exponential decrease, with maximum dose at the surface. Beam diameter was 3.1 cm at approximately 3 cm distance from the radiation source, with flatness deviation of 3.78% and symmetry of 98.8%. The non-uniform Luxel film was less effective for beam profiling.
Conclusion: This CCD-camera-based OSL dosimetry technique demonstrates Luxel's potential as a dosimeter with a linear dose response and effectiveness for low doses down to 1–2 mGy. A perfect Luxel film could improve beam parameter comparisons with Gafchromic film.