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X-Ray Fluorescence for Energy Response Calibration of a Photon Counting Detector: A Simulation Study

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H Cho

H Cho*, H Ding , B Ziemer , S Molloi , University of California, Irvine, CA


SU-E-I-67 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose:To investigate the feasibility of energy calibration and energy response characterization of a photon counting detector using x-ray fluorescence.

Methods:A comprehensive Monte Carlo simulation study was done to investigate the influence of various geometric components on the x-ray fluorescence measurement. Different materials, sizes, and detection angles were simulated using Geant4 Application for Tomographic Emission (GATE) Monte Carlo package. Simulations were conducted using 100 kVp tungsten-anode spectra with 2 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 x 3 mm2 in detection area. The fluorescence material was placed 300 mm away from both the x-ray source and the detector. For angular dependence measurement, the distance was decreased to 30 mm to reduce the simulation time. Compound materials, containing silver, barium, gadolinium, hafnium, and gold in cylindrical shape, were simulated. The object size varied from 5 to 100 mm in diameter. The angular dependence of fluorescence and scatter were simulated from 20° to 170° with an incremental step of 10° to optimize the fluorescence to scatter ratio. Furthermore, the angular dependence was also experimentally measured using a spectrometer (X-123CdTe, Amptek Inc., MA) to validate the simulation results.

Results:The detection angle between 120° to 160° resulted in more optimal x-ray fluorescence to scatter ratio. At a detection angle of 120°, the object size did not have a significant effect on the fluorescence to scatter ratio. The experimental results of fluorescence angular dependence are in good agreement with the simulation results. The Kα and Kβ peaks of five materials could be identified.

Conclusion:The simulation results show that the x-ray fluorescence procedure has the potential to be used for detector energy calibration and detector response characteristics by using the optimal system geometry.

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