Quantifying spatial resolution in a fast neutron radiography system

Oksuz, Ibrahim; Bisbee, Matt; Hall, James M.; Cherepy, Nerine J.; Cao, Lei

doi:10.1016/j.nima.2022.166331

Cited by 14 publications

(5 citation statements)

References 13 publications

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“…OSU Research Reactor is a 500 kW thermal, open pool-top, light water reactor, which features a 3.175 cm diameter collimated beam of fast and thermal neutrons [13]. The beam has 0.6° divergence at beam exit giving a nearly parallel beam [14]. The total neutron flux at beam exit was measured using multi-foil neutron activation analysis resulting in a total of 2.3x10 7 n⋅cm -2 ⋅s -1 (0.8x10 7 n⋅cm -2 ⋅s -1 below 0.5 eV and 1.5x10 7 n⋅cm -2 ⋅s -1 in the epi-cd to fast neutron energy range with a median of 1.6 MeV) at 450 kW [15].…”

Section: Imaging Facilitymentioning

confidence: 99%

Improved image stitching method for neutron imaging of large object with small beam size

Bisbee,

Oksuz,

Hetrick

et al. 2023

Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXV

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Imaging stitching is a solution for radiography and computed tomography (CT) applications where the object is larger than the beam size. Imaging stitching algorithms require a robust noise filter that maintains the landmark features used in stitching. In lens-coupled neutron radiography and CT, a camera is placed away from the neutron beam. Even with shielding, the camera experiences a high radiation dose of mixed gammas and neutrons. The CCD silicon sensor, sensitive to both gammas and neutrons, introduces speckled noise, pixel oversaturation, and blooming effects. Conventional median filters prove inadequate with this type of noise and can result in blurred images. Manual filtering of CT sets is timeconsuming and error-prone. An improved image filtering method designed for neutron CT data sets is therefore needed to improve imaging stitching algorithms. We have developed a method that utilizes statistical information in radiographs and variable-sized radii filtration to adequately remove noise while preserving resolution. Once noise has been identified, the algorithm tracks cluster size to inform local filter needs. Filtered radiographs are stitched using a semi-automatic algorithm. This approach works best for data containing features for joint corner detection. It does require specific user inputs, such as object size, features of interest, and alignment, to pinpoint the optimal joining location. Overall, our method represents a significant advancement in neutron CT image processing, offering improved results for imaging stitching and traditional CT applications. We describe the application of this combined filter and stitching algorithm on thermal and fast neutron CT data at OSURR.

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Section: Imaging Facilitymentioning

confidence: 99%

Improved image stitching method for neutron imaging of large object with small beam size

Bisbee,

Oksuz,

Hetrick

et al. 2023

Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXV

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“…The photons are then reflected by a reflection mirror, focused by a lens, and recorded by a CCD camera to provide an FNR image. In the developed detector, a 2 mm thick HDPE converter with a diameter of 76 mm is used to convert fast neutrons to recoil protons, with a conversion efficiency of 0.38% for 14 MeV fast neutron [15,16]. The HDPE is directly coupled with a V-stack dual MCPs, with a distance of approximately 0.1 mm between the HDPE and MCP.…”

Section: Jinst 18 T08004mentioning

confidence: 99%

Fast neutron radiography detector with polyethylene converter and MCP: development and performance evaluation

Bai

Liu

et al. 2023

J. Inst.

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We present a new position-sensitive fast neutron detector for 14 MeV fast neutron radiography, comprising a high-density polyethylene converter, a micro-channel plate (MCP), a P43 phosphor screen, a reflection mirror, and a CCD camera. Experimental tests are conducted using a DT neutron generator at CIAE, with different samples and a knife-edge measurement used to determine overall image resolution. Results show that the detector is feasible for fast neutron radiography, producing a fast neutron image with a neutron flux of ∼ 3.22 × 104 n · s-1 · cm-2 and 120 s exposure time. Our study demonstrates the potential of this detector for use in fast neutron radiography applications.

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“…The calculated L/D ratio of the beam is approximately 60. It has an experimentally determined beam divergence of 0.6° which enables an assumption of a quasi-parallel beam for reconstructions [12]. The imaging station utilized a scintillator with a lens-coupled camera for detection.…”

Section: Imaging Facilitiesmentioning

confidence: 99%

“…To keep the camera out of the direct path of neutrons, a front-surface flat mirror was used to reflect scintillation light. With this setup, the spatial resolution of the system was measured via the knife edge method with a 6.0 mm thick tantalum foil covering half the beam [12]. The calculated spatial resolution at 10% MTF is 231 µm.…”

Section: Imaging Facilitiesmentioning

confidence: 99%

“…MeV X-ray CT offers spatial resolution approximately 125 µm, with recent advancements in scintillator technology improving to 100-µm through a transparent ceramic (Gd,Lu,Eu)2O3 (GLO) scintillator. [5,11] The spatial resolution in fast neutron CT scanners is approximately 250 µm for lens-coupled systems with high light yield (Hi-LY) plastic scintillators [12]. A recent studying shows spatial resolution down to 176 µm [13].…”

Section: Introductionmentioning

confidence: 99%

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Experimental x-ray and fast neutron CT comparative analysis

Bisbee

Cherepy

2022

Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXIV

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X-ray computed tomography (CT) systems can produce high resolution images, in which small (sub-millimeter) features can be detected. This requires the X-rays to sufficiently penetrate the object and interact strongly enough to produce measurable attenuation. Low atomic number (low Z), low density objects shielded by high atomic number (high Z) materials result in X-ray reconstructions that lack sufficient contrast to differentiate interior features from noise and reconstruction artifacts. Fast neutron CT offers complementary information to X-rays with superior penetration through high Z shielding and with less severe beam hardening artifacts. However, spatial resolution in X-ray imaging systems is generally superior to that of fast neutron imagers. Here, we quantitatively compare these two complementary modalities to demonstrate the ability to observe small feature locations within two multi-material objects. Quantitative measures include calculation of image gradient at material edges, contrast-to-noise ratio, and F1 score.

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Quantifying spatial resolution in a fast neutron radiography system

Cited by 14 publications

References 13 publications

Improved image stitching method for neutron imaging of large object with small beam size

Improved image stitching method for neutron imaging of large object with small beam size

Fast neutron radiography detector with polyethylene converter and MCP: development and performance evaluation

Experimental x-ray and fast neutron CT comparative analysis

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