Corrections to Bremsstrahlung spectra for a hyperspectral x-ray detector

Oakley Clark; Matt Wilson; Philip Evans; Emma Harris; Silvia Pani

doi:10.1117/12.2652899

7 April 2023 Corrections to Bremsstrahlung spectra for a hyperspectral x-ray detector

Oakley Clark, Matt Wilson, Philip Evans, Emma Harris, Silvia Pani

Proceedings Volume 12463, Medical Imaging 2023: Physics of Medical Imaging; 1246328 (2023) https://doi.org/10.1117/12.2652899
Event: SPIE Medical Imaging, 2023, San Diego, California, United States

Conference Poster

Abstract

A Monte-Carlo model was developed to simulate the response of a pixelated hyperspectral CZT X-ray detector. The first part of the simulation was carried out using Geant4, to obtain a list of energy depositions inside the CZT crystal. The second part of the simulation used charge transport equations to calculate the size of the electron charge cloud, as it drifts under the electric field to be read out. Experimentally acquired data from an Am-241 source with the HEXITEC detector were compared to simulated data, and good agreement was found. The model was used to investigate the energy dependence of fluorescence and charge sharing effects. Firstly, the probability of producing an escaped fluorescence photon was quantified as a function of primary photon energy. As expected, at primary photon energies just above the K-edge of Cd, there is a greater chance of producing an escaped fluorescence photon, and this probability decreases as the primary photon energy increases. Secondly, the probability of an event being shared across multiple pixels as a function of primary photon energy was quantified. It was found that as the primary photon energy is increased, there is a greater chance of producing an event shared across multiple pixels. The detector response to a Bremsstrahlung spectrum was simulated. Using previous results, fluorescence and charge sharing effects were corrected for, giving a corrected spectrum in good agreement with the input spectrum.

Citation Download Citation

Oakley Clark, Matt Wilson, Philip Evans, Emma Harris, and Silvia Pani "Corrections to Bremsstrahlung spectra for a hyperspectral x-ray detector", Proc. SPIE 12463, Medical Imaging 2023: Physics of Medical Imaging, 1246328 (7 April 2023); https://doi.org/10.1117/12.2652899

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