Introduction to neutron stimulated emission computed tomography

Floyd, Carey E.; Bender, Janelle E.; Sharma, Ajeet D.; Kapadia, Anuj J.; Xia, Jessie Q.; Harrawood, Brian P.; Tourassi, Georgia D.; Lo, Joseph Y.; Crowell, A. S.; Howell, C. R.

doi:10.1088/0031-9155/51/14/006

Cited by 44 publications

(27 citation statements)

References 38 publications

(35 reference statements)

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“…NSECT generates elemental composition images by illuminating the region-of-interest with a high-energy (3)(4)(5) beam of neutrons. These neutrons scatter inelastically off the body's elemental nuclei, exciting them and causing them to emit characteristic gamma radiation.…”

Section: Introductionmentioning

confidence: 99%

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Design and Development of a High-Energy Gamma Camera for Use With NSECT Imaging: Feasibility for Breast Imaging

Sharma

Tourassi

Kapadia

et al. 2007

IEEE Trans. Nucl. Sci.

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A new spectroscopic imaging technique, Neutron Stimulated Emission Computed Tomography (NSECT), is currently being developed to non-invasively and non-destructively measure and image elemental concentrations within the body. NSECT has potential for use in breast imaging as several studies have shown a link between elemental concentration and tumor status. In NSECT, a region of interest is illuminated with a high-energy (3-5 MeV) beam of neutrons that scatter inelastically with elemental nuclei within the body. The characteristic gamma rays that are emitted as the excited nuclei relax allow the identification of elements and the formation of elemental composition images. This imaging technique requires high-resolution and high-energy gamma spectroscopy; thereby eliminating current scintillation crystal based position sensitive gamma cameras. Instead, we propose to adapt high-energy gamma imaging techniques used in space-based imaging. A High Purity Germanium (HPGe) detector provides high-resolution energy spectra while a rotating modulation collimator (RMC) placed in front of the detector modulates the incoming signal to provide spatial information. Counting the number of gamma events at each collimator rotation angle allows for reconstruction of images. Herein we report on the design and testing of a prototype RMC, a Monte Carlo simulation of this camera, and the use of this simulation tool to access the feasibility of imaging a breast with such a camera. The prototype RMC was tested with a 22 Na point source and verified that the RMC modulates the gamma rays in a predictable manner. The Monte Carlo simulation accurately modeled this behavior. Other simulations were used to accurately reconstruct images of a point source located within a 10 cm cube, suggesting NSECT's potential as a breast imaging method.

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Section: Introductionmentioning

confidence: 99%

“…By detecting these gammas with a high-spectral-resolution detector, it is possible to identify the elements present within the sample. Furthermore, gathering these gammas in a tomographic geometry allows for the formation of elemental concentration images [2], [3].…”

Section: Introductionmentioning

confidence: 99%

Design and Development of a High-Energy Gamma Camera for Use With NSECT Imaging: Feasibility for Breast Imaging

Sharma

Tourassi

Kapadia

et al. 2007

IEEE Trans. Nucl. Sci.

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“…Data is acquired by illuminating the sample with the beam and counting until sufficient gamma events have been acquired to quantify the element with a p-value 0.05. The system has been described in detail elsewhere [3,6]. A simulation of this setup was implemented in GEANT4 as described below.…”

Section: Methodsmentioning

confidence: 99%

“…Diagnosis of iron overload requires an invasive biopsy [2], which is an unpleasant procedure with several associated complications including death. Neutron stimulated emission computed tomography (NSECT) is being developed as a non-invasive alternative to measure element concentration in the liver to diagnose liver iron overload [3][4][5]. Preliminary experiments have demonstrated NSECT's potential in quantifying concentrations of iron and potassium in bovine liver tissue [4,5].…”

Section: Introductionmentioning

confidence: 99%

GEANT4 simulation of an NSECT system for iron overload detection

Kapadia

Sharma

Harrawood

et al. 2007

2007 IEEE Nuclear Science Symposium Conference Record

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Hemochromatosis (iron overload in liver) is a condition that causes serious consequences for the patient through an increase in the body's iron stores. Diagnosis of the excess iron, which is often stored in the liver, requires an invasive biopsy. We are developing neutron stimulated emission computed tomography (NSECT) as a non-invasive alternative to measure liver iron concentration to diagnose hemochromatosis. This measurement is performed using an incident neutron beam that scatters inelastically with iron nuclei in the liver, causing them to emit characteristic gamma-rays. An energy-sensitive gamma-ray detector is used to detect these gamma-rays and quantify the iron in the liver. Preliminary experiments have demonstrated an implementation of NSECT to quantify concentrations of iron and potassium in bovine liver tissue. Due to the prohibitive nature of these experiments, it is not feasible to perform system evaluation and optimization at each step using a nuclear accelerator. Here we describe a GEANT4 simulation of NSECT as a feasible alternative to perform system evaluation for iron overload diagnosis using computing resources only. The simulation model uses a 5 MeV neutron beam to scan a human liver phantom with induced iron overload. The liver is modeled as a composite shape combining a half-cylinder and a polyhedron, and is housed in a human torso filled with water. Gamma-ray spectra are generated to show element concentration within the liver. To determine the lower limit of iron overload detection, the concentration of iron in the liver is reduced from an initial high value, and the p-value of detecting peaks corresponding to iron is calculated at each step. The lower limit of detection is defined as the concentration at which the p-value of peak detection exceeds 0.05. The limit of iron overload detection from this simulation was found to be 4 mg/g, which represents a clinically relevant value for iron overload.

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“…Currently MeV γ -ray spectroscopy has been desired in many fields, such as detection of explosive [4], prompt γ -ray imaging for small animals [5], and neutron stimulated ECT [6,7]. Unfortunately, there is no existing γ -ray spectroscopy that performs perfectly in such energy range and some detector systems have been proposed for the purpose [4,7]. In this note, we describe a simple γ -ray detector configuration and give the performance based on plastic scintillating optical fiber array.…”

Section: Introductionmentioning

confidence: 99%