# Title: Simulation of Beam Hardending in CT
# Presenter: Maciej Zajkowski
# Date: 17.03 2025
# Participants:
Wojciech Krzemień (WK)
Konrad Klimaszewski (KK)
Maciej Zajkowski (MZ)
Dominik Strzelecki (DS)
Michał Obara (MO)
Michał Mazurek (MM)
Aleksander Ogonowski (AO)
Michal Mrozowski (MMr)
Arkadiusz Ćwiek (AC)
Lech Raczynski (LR)
# Discussion:
(WK) Is this effect dependent on the shape of the object? I guess it must be, cause if the object just removed the lower energy photons uniformly then it
would not affect the final image.
KK/MZ: The attenuation will depend on the path of the photons through the object. So near the edges more photons would pass.
WK: What does it mean - X different simulations?
MZ: Each simulation with a different energy set. Later it is summed with weights taken from the relative intensity spectrum.
KK: I don't think it is dependent on the material. The energy profile in the discussed paper is obtained by minimization of results from measurements of samples from three materials. The relative intensity weights are obtained by minimising differences between simulated and measured data.
MZ: The beam energy in this study was set rather high as it considered dense metal samples.
WK: Are those metrics defined on profiles?
MZ: Yes
WK: When do you apply the corrections?
MZ: We apply it at the sinogram level before the reconstruction.
KK: Corrected means that we try transforming from multichromatic to mono-energetic case
WK: What is the typical beam spread?
MZ: As in the Figure. From 0-150 keV.
WK: Can this effect be solved by replacing the source beam with a more monochromatic one?
MZ: For economic reasons that would be not feasible.
KK: The synchrotron beam would be a good solution, but of course one needs to have access to the synchrotron.