The elemental analysis of the human body using associated particle timing based on the D + D reaction

Monte Carlo simulations of elemental imaging using the neutron‐associated particle technique

“…Iron was selected as the element of interest because it is known to frequently be present at elevated concentrations in cancerous tissue and diseased brain tissue as opposed to healthy tissue . The 1 cm dimensions of each voxel were chosen as an estimate of spatial resolution which would be valuable for in vivo applications . The 9‐voxel target array was suspended in air such that the leading edge of the center voxel was exactly 8 cm from the neutron source spot.…”

“…Therefore, in order to model depth resolution realistically, the overall timing resolution (including the error attributed to both the position‐sensitive ion detector and HPGe detectors) was introduced mathematically. While timing resolutions for NaI‐based systems and HPGe‐based systems traditionally range from 100–1000 picoseconds (ps), respectively, the timing resolution of HPGe detectors has been observed to approach that achievable using NaI detectors by employing constant fraction discrimination to allow much more rapid pulse processing . Therefore, because the total timing error is expected to be dominated by the gamma‐ray detector timing uncertainty, 225 ps was chosen as the total timing error ( σ ) in this study — representative of a readily achievable NaI timing resolution and optimized HPGe timing resolution.…”

“…While timing resolutions for NaI-based systems and HPGe-based systems traditionally range from 100-1000 picoseconds (ps), respectively, the timing resolution of HPGe detectors has been observed to approach that achievable using NaI detectors by employing constant fraction discrimination to allow much more rapid pulse processing. 6,22,31 Therefore, because the total timing error is expected to be dominated by the gamma-ray detector timing uncertainty, 225 ps was chosen as the total timing error (r) in this studyrepresentative of a readily achievable NaI timing resolution and optimized HPGe timing resolution. Then, by applying Gaussian-distributed uncertainty with r = 225 ps along each tagged neutron's travel vector to its simulated point of first collision with a Fe-56 nucleus in the target array, an image of iron concentration which was indicative of realistic depth resolution was obtained.…”

“…20,21 The 1 cm dimensions of each voxel were chosen as an estimate of spatial resolution which would be valuable for in vivo applications. 11,22 The 9-voxel target array was suspended in air such that the leading edge of the center voxel was exactly 8 cm from the neutron source spot. The source spotthat from which the 2.45 MeV DD neutrons were emittedwas defined as a circular surface source with negligible depth, 2 mm diameter, and a Gaussian-distributed and isotropic emission profile.…”

Associated particle neutron elemental imaging in vivo: A feasibility study

“…The liver voxel was assigned a volume of 1 cm 3 as a preliminary estimate of discernible spatial resolution in vivo. 23 With 2×10 9 neutrons emitted isotropically from the point source located 8 cm from the liver voxel, the simulated number of neutrons per unit area inside the voxel was 2.5×10 6 n/cm 2 . It is expected that because this model assumes a relatively superficial iron-containing target within the liver, the source neutron flux at the voxel will be close to the 2.5×10 6 n/cm 2 calculated previously even upon attenuation by approximately 5 cm of soft tissue.…”