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Title: 1D fast coded aperture camera

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Publication Date:
Sponsoring Org.:
OSTI Identifier:
Grant/Contract Number:
FG02-04ER54755; SC0010471
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 86; Journal Issue: 4; Related Information: CHORUS Timestamp: 2016-12-26 14:59:49; Journal ID: ISSN 0034-6748
American Institute of Physics
Country of Publication:
United States

Citation Formats

Haw, Magnus, and Bellan, Paul. 1D fast coded aperture camera. United States: N. p., 2015. Web. doi:10.1063/1.4917345.
Haw, Magnus, & Bellan, Paul. 1D fast coded aperture camera. United States. doi:10.1063/1.4917345.
Haw, Magnus, and Bellan, Paul. 2015. "1D fast coded aperture camera". United States. doi:10.1063/1.4917345.
title = {1D fast coded aperture camera},
author = {Haw, Magnus and Bellan, Paul},
abstractNote = {},
doi = {10.1063/1.4917345},
journal = {Review of Scientific Instruments},
number = 4,
volume = 86,
place = {United States},
year = 2015,
month = 4

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4917345

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  • The authors have developed a near field coded aperture imaging system for use with fast neutron techniques as a tool for the detection of contraband and hidden explosives through nuclear elemental analysis. The technique relies on the prompt gamma rays produced by fast neutron interactions with the object being examined. The position of the nuclear elements is determined by the location of the gamma emitters. For existing fast neutron techniques, in Pulsed Fast Neutron Analysis (PFNA), neutrons are used with very low efficiency; in Fast Neutron Analysis (FNS), the sensitivity for detection of the signature gamma rays is very low.more » For the Coded Aperture Fast Neutron Analysis (CAFNA{reg{underscore}sign}) the authors have developed, the efficiency for both using the probing fast neutrons and detecting the prompt gamma rays is high. For a probed volume of n{sup 3} volume elements (voxels) in a cube of n resolution elements on a side, they can compare the sensitivity with other neutron probing techniques. As compared to PFNA, the improvement for neutron utilization is n{sup 2}, where the total number of voxels in the object being examined is n{sup 3}. Compared to FNA, the improvement for gamma-ray imaging is proportional to the total open area of the coded aperture plane; a typical value is n{sup 2}/2, where n{sup 2} is the number of total detector resolution elements or the number of pixels in an object layer. It should be noted that the actual signal to noise ratio of a system depends also on the nature and distribution of background events and this comparison may reduce somewhat the effective sensitivity of CAFNA. They have performed analysis, Monte Carlo simulations, and preliminary experiments using low and high energy gamma-ray sources. The results show that a high sensitivity 3-D contraband imaging and detection system can be realized by using CAFNA.« less
  • Fast neutron analysis is a technique for determination of the elemental composition of materials in bulk by detecting the energies of characteristic gamma rays, which are emitted by elements after a neutron interaction. These gamma rays are typically in the 2 to 6 MeV range and it is desired to image them with a high efficiency system. Coded aperture imaging is a technique, which can improve system sensitivity by as much as a factor of fifty as compared to conventional collimators. Such systems have been used in x-ray astronomy, but unlike x-ray astronomy, our system is designed for near fieldmore » imaging. The choice of pattern is critical to the performance of the system but we have devised patterns such that the reconstruction of point like objects is clean and rapid with no spurious response. We have also used the technique for imaging of high energy radioisotopes used in nuclear medicine.« less
  • Aperture alignment is crucial for the diagnosis of neutron imaging because it has significant impact on the coding imaging and the understanding of the neutron source. In our previous studies on the neutron imaging system with coded aperture for large field of view, “residual watermark,” certain extra information that overlies reconstructed image and has nothing to do with the source is discovered if the peak normalization is employed in genetic algorithms (GA) to reconstruct the source image. Some studies on basic properties of residual watermark indicate that the residual watermark can characterize coded aperture and can thus be used tomore » determine the location of coded aperture relative to the system axis. In this paper, we have further analyzed the essential conditions for the existence of residual watermark and the requirements of the reconstruction algorithm for the emergence of residual watermark. A gamma coded imaging experiment has been performed to verify the existence of residual watermark. Based on the residual watermark, a correction method for the aperture misalignment has been studied. A multiple linear regression model of the position of coded aperture axis, the position of residual watermark center, and the gray barycenter of neutron source with twenty training samples has been set up. Using the regression model and verification samples, we have found the position of the coded aperture axis relative to the system axis with an accuracy of approximately 20 μm. Conclusively, a novel approach has been established to correct the coded aperture misalignment for fast neutron coded imaging.« less
  • Coded aperture imaging (CAI) and multiple-view pinhole imaging (MVPI) of the thyroid were compared in 19 patients to determine whether CAI's theoretical advantages of high resolution high efficiency, freedom from distortion, accurate size representation, and tomographic presentation could be realized in the clinical setting, and to determine whether CAI offers any advantage over conventional MVPI. The coded aperture images were judged better than the pinhole images in five cases, equal in 13 cases, and worse in one case. The major problem with CAI was the long reconstruction time. Further development and an extended clinical trial appear warranted.