Optimization of a CZT photon counting detector for contaminant detection

Abstract

In the food industry, X-ray inspection systems are utilized to ensure packaged food is free from physical contaminants to maintain a high level of food safety for consumers. However, one of the challenges in the food industry is detecting small, low-density contaminants from packaged food. Cadmium zinc telluride (CZT) photon counting detectors (PCDs) can potentially alleviate this problem given its multi-energy bin capabilities, high spatial resolution and ability to eliminate electronic noise, which is superior to the conventional energy integrating detector (EID). However, the image quality from a CZT PCD can be further improved by applying an optimized energy bin weighting scheme that maximizes energy bin images that provide the largest image contrast and lowest image noise. Therefore, in this work, five contaminant materials embedded in an acrylic phantom were imaged using a CZT PCD while the phantom was in constant motion to mimic food products moving on a conveyor belt. Energy bin optimization was performed by applying an image-based weighting scheme and these results showed contrast-to-noise ratio (CNR) improvements ranging between 1.02–1.91 relative to an equivalent EID acquisition.

Advances in High-Energy-Resolution CdZnTe Linear Array Pixel Detectors with Fast and Low Noise Readout Electronics

“…Energy-resolved photon counting (ERPC) systems are object of increasing research interest due to their large impact in scientific, medical, and industrial applications, from computed tomography (CT) to inline inspection in food and pharma production chains, or material recycling processes [ 1 , 2 , 3 , 4 ]. Among compound semiconductors, detectors based on Cadmium Zinc Telluride (CdZnTe or CZT) are promising candidates for the development of next-generation ERPC systems, mainly competing with Cadmium Telluride (CdTe) detectors for room temperature operation, both being characterized by a wide band-gap, high stopping power, and the possibility to be realized in thick pixelated structures.…”

Window-Based Energy Selecting X-ray Imaging and Charge Sharing in Cadmium Zinc Telluride Linear Array Detectors for Contaminant Detection

“…The importance of energy-resolved photon counting (ERPC) systems for quality enhancements in X-ray images is now widely recognized [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Due to the energy-dependence of the X-ray attenuation processes, spectral X-ray imaging represents a key tool for high resolution material detection and quantitative analysis, especially for medical diagnosis [ 4 , 5 , 9 , 10 ] and non-destructive testing (NDT) in security and food industry [ 6 , 7 , 8 ]. Once the spectral images are acquired, different techniques and algorithms can be easily applied to combine and weight the energy-binned images.…”

“…While the advantages of the energy-resolved approach have been well demonstrated in several studies [ 9 , 10 , 11 , 12 ], the development of ERPC systems with high spatial and energy resolution is still currently under research and development. ERPC prototypes based on room temperature compound semiconductor detectors have given the best results, ensuring direct photon counting detection and good room temperature energy/spatial resolution [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Among these materials, cadmium zinc telluride (CdZnTe or CZT) has reached an excellent maturity level in room temperature X-ray and gamma-ray detection from photon energies of few keV up to 1 MeV [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ].…”

“…ERPC prototypes based on room temperature compound semiconductor detectors have given the best results, ensuring direct photon counting detection and good room temperature energy/spatial resolution [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Among these materials, cadmium zinc telluride (CdZnTe or CZT) has reached an excellent maturity level in room temperature X-ray and gamma-ray detection from photon energies of few keV up to 1 MeV [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Recently, in the framework of the AVATAR X project (funded by the Italian Ministry for University and Research), we developed ERPC systems based on sub-millimetre CZT linear array detectors for contaminant detection in food industry.…”

Incomplete Charge Collection at Inter-Pixel Gap in Low- and High-Flux Cadmium Zinc Telluride Pixel Detectors

“…After the first CZT detector was presented by Butler in 1992 [12], intense research activities started with important progress made in both crystal growth and electrical contact technology. CZT detectors with pixel and strip electrodes were widely developed for X-ray and gamma-ray spectroscopic imaging, meeting the different requirements of many applications, including diagnostic-nuclear medicine [4][5][6][7], astrophysics [8][9][10][11], security [1], and non-destructive testing in the food industry [13,14]. Typically, the best-spectroscopic-grade CZT crystals are grown via Bridgman (B) [15][16][17][18] and traveling heater method (THM) growth [18][19][20][21][22] techniques.…”