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High-resolution photon-counting detector (PCD) computed tomography (CT) imaging is increasingly used for several applications. Recent technological advances in CT instrumentation have introduced various types of radiation detectors. Therefore, this work aims at evaluating the lutetium–yttrium oxyorthosilicate (LYSO) scintillator for use in PCD CT from a detector point of view. To do so, a mini-CT prototype was designed and constructed based on the pixelated LYSO blocks. The detector comprises four 10 × 10 linearly arranged LYSO blocks coupled with four position-sensitive photomultiplier tubes. The prototype utilizes a point gamma-ray source along with a cone-beam collimator. An in-home MATLAB-based data processing software package was also developed for storing the list-mode data, event positioning, and energy windowing. A set of experiments were conducted to assess the performance of the constructed energy-resolved LYSO:Ce detector for mini-CT imaging. The results show good crystal identification for all blocks with a maximum peak-to-valley ratio of 3.48. In addition, the findings confirm that the developed detector is position-sensitive. The 20% energy window provides an optimal performance by simultaneously providing good crystal identification and a scatter removal factor of 0.71. A 96% uniformity was also observed when the detector was irradiated with a uniform flood. The spatial resolution of the mini-CT prototype in the x- and y-directions was calculated to be 0.9 and 0.93 mm, respectively, corrected for a magnification factor of 2.5. It is concluded that the pixelated LYSO crystal is a promising alternative to the current detectors and would be the scintillator of choice for high-resolution PCD CT imaging tasks. [ABSTRACT FROM AUTHOR]

Monitoring wax deposition in pipelines is of particular importance for oil extraction companies. In this work, a new gamma-ray tomography system based on using a rod CsI(Na) scintillator and 137Cs gamma source was developed to view the cross section of oil pipelines. The system can estimate the interaction position of gamma-rays by measuring light attenuation in the rod scintillator using two photomultiplier tubes coupled to its ends. Therefore, despite the simple structure of the employed detector, it can act as a position-sensitive instrument. In order to test the proposed tomography system, a selection of desired polyethylene round-bar pieces (as different wax thicknesses) was prepared to be placed in iron pipes, and their projections at different angles were acquired to construct cross-sectional images as well. The results showed that the designed system had the ability to scan the interior of the pipes and determine wax thickness with an error between 2.4% and 11.4%. [ABSTRACT FROM AUTHOR]

Abstract Gamma-ray Computed Tomography is an important tool for accessing the internal details of large objects in different industries such as oil, gas, petrochemical, etc. In this paper, a Geant4 study was performed to develop a new approach for this type of tomography by using high aspect ratio scintillators. In this method, a NaI(Tl) rectangular cube scintillator, coupled to a PMT on each side in a coincidence setup, was considered as a position sensitive detector. Different responses of the detector including the scintillation processes in presence of 662 keV gamma-rays of a Cs-137 were simulated. Spectral response, position and energy resolutions were obtained and compared to the experimental data. The comparisons showed a good agreement between the simulation results and experimental data. Furthermore, the detector was simulated in a gamma-ray tomography setup and the related projections and cross sectional images of a standard phantom were obtained. The obtained results showed that the high aspect ratio scintillator detector can be used instead of array detector in industrial applications where there is no need to very high position resolutions. [ABSTRACT FROM AUTHOR]

Reflective materials have an important role in designing the high performance scintillator-based detectors. The optical reflectivity of these materials has an undeniable effect on the efficiency of these detectors. This parameter is also very important in Monte Carlo simulations of the scintillators. In this work, a new method based on the both gamma-ray spectroscopy and Geant4 simulation is proposed to predict the reflectivity of the reflectors employed in radiation detection setups. [ABSTRACT FROM AUTHOR]

The objective of this paper was to investigate a detection system based on a CsI(Na) rod scintillator for the use in industrial gamma-ray computed tomography. For this goal to be achieved, a CsI(Na) rod scintillator was first grown using the Czochralski method. The scintillation response of the rod scintillator was then assessed. Furthermore, the detection system was employed to determine the positions and energies of incident gamma-rays in a tomography system. Two different phantoms were also constructed to assess the basic characteristics of the system. Results showed that the proposed tomography system has a good performance in industrial applications. [ABSTRACT FROM AUTHOR]