<p>A novel system has been simulated with accompanying
experimental data that is designed to provide spatial information of elemental
concentrations at biologically relevant levels.
Using a deuterium-deuterium (DD) neutron generator, two large
high-purity germanium (HPGe) detectors operating in tandem, and the associated
particle imaging (API) technique, elemental iron concentrations as low as 100
ppm have been resolved <i>in vivo</i> in the
liver of a simulated reference man with an equivalent dose to the region of
interest of < 5 mSv and an estimated whole body dose of 0.82 mSv. Using the Monte Carlo Neutral Particle (MCNP)
transport code, achievable spatial resolutions in the projective and depth
dimensions of < 1 cm and < 3 cm are achievable, respectively, for
iron-containing voxels on the order of 1,000 ppm Fe – with an overall 225 ps
system timing resolution, 6.25 mm<sup>2</sup> imaging plate pixels, and a
Gaussian-distributed DD neutron source spot with a diameter of 2 mm. Additionally, as a departure from Monte Carlo
simulations, the underlying concepts of fast neutron inelastic scatter analysis
as an initial surrogate to true associated particle neutron elemental imaging
(APNEI) were demonstrated using a DD neutron generator, iron-made interrogation
targets, a sodium iodide detector, and physical neutron/gamma shielding, which
yielded an approximate detection limit for iron of 3.45 kg which was simulated
to improve to 0.44 kg upon incorporation of the associated particle collimation
methodology.</p>
The
API technique allows concentrations of elements such as iron to be quantified
due to time-tagged electronic collimation and corresponding background signal
reduction. Inherent to the API process
is the collection of spatial and temporal information, which allows the
perceived origin of a photon signal to be identified in 3D space. This process was modeled algorithmically in
MCNP and employed using relevant equipment and shielding geometries. By leveraging the capabilities of modern-day neutron
generator and coincident timing technologies with high throughput signal
processing discrimination, the applicability of APNEI to disease diagnostics
and etiological research is promising.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/8001488 |
| Date | 10 June 2019 |
| Creators | Michael R Abel (6594194) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/ASSOCIATED_PARTICLE_NEUTRON_ELEMENTAL_IMAGING_FOR_NONINVASIVE_MEDICAL_DIAGNOSTICS/8001488 |
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