The presented work describes the capabilities of a
state-of-the-art spectroscopic photon-counting hybrid pixel detector
for use in non-destructive testing, as a contaminant detector with
potential uses in the food and pharmaceutical industries. A
pharmaceutical hard capsule containing vitamin powder, contaminated
with Steel (ST) and Tungsten (W) was prepared under controlled
conditions. Both contaminants are distinguished from the powder by
combining sub-pixel imaging with spectroscopic imaging analysis,
made possible by the use of a 2 mm CdZnTe sensor coupled to a
Timepix3 ASIC, operated in Time-over-Threshold and Time-of-Arrival
mode. The sub-pixelization technique achieves a spatial resolution
of 18.3 μm, with a maximum photon flux of
2.5× 106 photons/s· cm2. For the spectral
analysis technique implemented, each energy bin image is
energy-weighted, with weights optimally defined by considering the
bin contrast and noise behavior, and combined to form an
integrated-spectrum enhanced image with increased contaminant
visibility. Contrast-to-Noise Ratio (CNR) for each contaminant type
was used for performance assessment of the approach. A CNR increase
of 106% above the reference unweighted-spectrum image was achieved
for the ST contaminant, while the denser W contaminant showed a CNR
increase of 80%. This means that the presented spectroscopic
imaging technique is feasible for implementation in material
visibility enhancement.
Despite the benefits of mammography investigations, some studies have shown that X-ray exposure from the mammography screening itself can statistically cause breast cancer in a small fraction of women. Therefore, a dose reduction in mammography is desirable. At the same time, there is a demand for a higher spatial resolution in mammographic imaging. The most promising way to achieve these goals is the use of advanced photonprocessing semiconductor X-ray detectors with optimum sensor materials. This study addresses the investigation of the optimum semiconductor sensor material for mammography in combination with the photon-processing detector Medipix3RX. The influence of K-shell fluorescence from the sensor material on the achievable contrast-to-noise ratio is investigated, as well as the attenuation efficiency. The three different sensor materials, CdTe, GaAs, and Si are studied, showing advances of CdTe-sensors for mammography. Furthermore, a comparison of the contrast-to-noise ratio between a clinical Se-detector and Medipix3RX detectors with Si-and CdTe-sensors is shown using a self-produced mammography phantom that is based on real human tissue.
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