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Coded Aperture X-Ray Diffraction Tomography
Published in Joel Greenberg, Krzysztof Iniewski, X-Ray Diffraction Imaging, 2018
The presence of a coded aperture significantly improves the overall system performance for all SNR and view numbers as compared to the uncoded case. Thus, in the interpretation of this measurement approach as a form of limited-view, compressive CSCT (rather than multi-view CA-XRDT), it can be seen that the improved conditioning provided by the code outweighs the fact that approximately half of the X-rays are blocked by the code, which is consistent with the results of Kaganovsky et al. for coded, compressive CT.92 This opens up potential applications for realizing simultaneously high-throughput and high-resolution XRD-based imaging.
Special Techniques
Published in Harry E. Martz, Clint M. Logan, Daniel J. Schneberk, Peter J. Shull, X-Ray Imaging, 2016
Harry E. Martz, Clint M. Logan, Daniel J. Schneberk, Peter J. Shull
One advantage of coded aperture cameras in some applications is that depth information is encoded into the image along with the other two image dimensions. This means that the 3D location of a source can be decoded from a single image with a coded aperture camera. Two situations where this is potentially useful are in nuclear medicine applications (Meikle et al. 2002) and materials science (Haboub et al. 2012; MacCabe et al. 2012).
Minimal Detection Time for Localization of Radioactive Hot Spots in Low and Elevated Background Environments Using a CZT Gamma-Ray Spectrometer
Published in Nuclear Technology, 2022
Lowie Brabants, Mattias Simons, David de Schepper, Eric Demeester, Wouter Schroeyers
Typically, pinhole cameras offer a wide energy range and good angular resolution but are heavy, have a small field of view, and have extremely low sensitivity. On the other hand, coded-aperture cameras have a higher sensitivity as they use a coded mask with multiple holes arranged in a particular order, but they require an additional decoding step. They achieve similar characteristics to a pinhole camera in angular resolution and field of view. The third category, Compton cameras, makes use of the kinematics of Compton scattering to localize radiation sources without using collimators. As a result, Compton cameras have an optimal field of view (up to 360 deg) and high-energy resolution. A downside to the Compton cameras is that they have a limited angular resolution and are not able to localize gamma rays with energies below 250 keV (Ref. 9).
Research on a Monte Carlo Simulation Method of Neutron Coded-Aperture Imaging
Published in Nuclear Science and Engineering, 2022
Huayang Zhang, Bin Zhong, Huayun Shen, Li Cheng, Jinhong Li
Particle imaging techniques can be generally divided into two categories. Radiograph is mainly used for nondestructive detection,1,2 and pinhole imaging is used for detecting the radiation field distribution of radioactive objects.3 A pinhole imaging system consists of a shielding pinhole or coded-apertures and a detector array of surface imaging. The particles emitted by the radiator, passing through the pinhole, are received by the detector array and then counted. After processing the flux measured by the detector array, the planar distribution of flux from the radiator is obtained. The size of the pinhole affects the resolution and signal strength of the imaging system. Higher resolution could be achieved by using a smaller pinhole, however, at a cost of signal strength. Hence a trade-off is necessary in practical applications. In order to improve the signal strength while maintaining good resolution for small apertures, a coded-aperture imaging technique has been developed and gradually improved.4 Coded-aperture imaging has been widely used in the study of inertial confinement fusion (ICF) diagnosis,5–8 radioactive source localization,9 and nonproliferation and arms control verification.10 Taking the ICF experiment as an example, the spatial distribution of the 14.1-MeV neutrons generated by deuterium-tritium fusion reflects the shape, size, and homogeneity of the compression region of the fuel during implosion; the downscattering neutrons (6 to 12 MeV) can provide information about the distribution around the hot spot of the cold fuel in high density.5
Influence of Doppler broadening model accuracy in Compton camera list-mode MLEM reconstruction
Published in Inverse Problems in Science and Engineering, 2021
Yuemeng Feng, Jean Michel Létang, David Sarrut, Voichia Maxim
Using the Compton camera to detect γ rays was proposed during 1970s simultaneously for astronomical [1] and nuclear medicine [2] imaging applications. Its advantage over other devices such as the widely employed collimated cameras and the coded aperture is the large angle acceptance. To identify the direction of an incoming γ ray, the camera makes use of a coincidence mechanism based on Compton scattering. More recently, its application to ion-range monitoring in proton and hadron-therapy through prompt-gamma detection was proposed. The energies of the prompt-γ rays are in this case too large to cope with parallel-hole acquisition, unless hard collimation is employed [3,4], and this complicates three-dimensional imaging and reduces the resolution.