Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Computed Tomography imaging of large cargos   A feasibility study of the megavoltage (MV) computed tomography (CT) for
imaging large cargos has been performed. The MV cargo CT system has imaging
field of view of 3.25m in diameter. The system design includes a compact x-ray
source and detectors that are already used in existing MV cargo radiography
systems. Although compact x-ray sources provide limited x-ray output, it is
shown that this output is sufficient to perform CT imaging of large cluttered
cargo contents for which MV radiography may be inconclusive. The scan time is
60sec. at the x-ray dose levels lower than the permitted limit of 5mGy. A steel
tank phantom with 2m diameter including different materials was used. The MV CT
images were generated at 3.5MV, 6MV, and 9MV beam energies. The materials were
separated based on their CT numbers as well as using dual energy subtraction
method. The materials with close densities and x-ray attenuations such as W and
U were reliably separated and quantified based on their measured CT numbers.
The boundary conditions for the system design were determined including scan
time, radiation dose, maximum object thicknesses, and spatial resolution. Based
on the findings of this feasibility study, it is concluded that the MV cargo CT
system with large field of view can be developed based on existing technology
already used in MV cargo radiography. Such a CT system can be extremely useful
as adjunct to existing MV radiography on resolving the special cases that
cannot be resolved conclusively with radiography alone.

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The categories of this paper are: dg-ga
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The categories of this paper are: eess
13
The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol