Bibliografie tematiche / 3-Gamma imaging

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Letteratura scientifica selezionata sul tema "3-Gamma imaging"

Autore: Grafiati

Pubblicato: 14 settembre 2024

Ultima modifica: 19 giugno 2025

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Articoli di riviste sul tema "3-Gamma imaging"

Haefner, Andrew, Ross Barnowski, Paul Luke, Mark Amman, and Kai Vetter. "Handheld real-time volumetric 3-D gamma-ray imaging." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 857 (June 2017): 42–49. http://dx.doi.org/10.1016/j.nima.2016.11.046.

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Vetter, Kai, Ross Barnowksi, Andrew Haefner, Tenzing H. Y. Joshi, Ryan Pavlovsky, and Brian J. Quiter. "Gamma-Ray imaging for nuclear security and safety: Towards 3-D gamma-ray vision." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 878 (January 2018): 159–68. http://dx.doi.org/10.1016/j.nima.2017.08.040.

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Hu, Yifan, Zhenlei Lyu, Peng Fan та ін. "A Wide Energy Range and 4π-View Gamma Camera with Interspaced Position-Sensitive Scintillator Array and Embedded Heavy Metal Bars". Sensors 23, № 2 (2023): 953. http://dx.doi.org/10.3390/s23020953.

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Abstract (sommario):

(1) Background: Gamma cameras have wide applications in industry, including nuclear power plant monitoring, emergency response, and homeland security. The desirable properties of a gamma camera include small weight, good resolution, large field of view (FOV), and wide imageable source energy range. Compton cameras can have a 4π FOV but have limited sensitivity at low energy. Coded-aperture gamma cameras are operatable at a wide photon energy range but typically have a limited FOV and increased weight due to the thick heavy metal collimators and shielding. In our lab, we previously proposed a 4π-view gamma imaging approach with a 3D position-sensitive detector, with which each detector element acts as the collimator for other detector elements. We presented promising imaging performance for 99mTc, 18F, and 137Cs sources. However, the imaging performance for middle- and high-energy sources requires further improvement. (2) Methods: In this study, we present a new gamma camera design to achieve satisfactory imaging performance in a wide gamma energy range. The proposed gamma camera consists of interspaced bar-shaped GAGG (Ce) crystals and tungsten absorbers. The metal bars enhance collimation for high-energy gamma photons without sacrificing the FOV. We assembled a gamma camera prototype and conducted experiments to evaluate the gamma camera’s performance for imaging 57Co, 137Cs, and 60Co point sources. (3) Results: Results show that the proposed gamma camera achieves a positioning accuracy of <3° for all gamma energies. It can clearly resolve two 137Cs point sources with 10° separation, two 57Co and two 60Co point sources with 20° separation, as well as a 2 × 3 137Cs point-source array with 20° separation. (4) Conclusions: We conclude that the proposed gamma camera design has comprehensive merits, including portability, 4π-view FOV, and good angular resolution across a wide energy range. The presented approach has promising potential in nuclear security applications.

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Chmeissani, Mokhtar, Machiel Kolstein, Gerard Ariño-Estrada, José Gabriel Macias-Montero, Carles Puigdengoles, and Jorge García. "Tracking a moving point source using triple gamma imaging." Journal of Instrumentation 19, no. 01 (2024): P01001. http://dx.doi.org/10.1088/1748-0221/19/01/p01001.

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Abstract With positron emission tomography (PET), the positron of a β + emitter radioisotope annihilates with a nearby electron producing a pair of back-to-back 511 keV gamma rays that can be detected in a scanner surrounding the point source. The position of the point source is somewhere along the Line of Response (LOR) that passes through the positions where the 511 keV gammas are detected. In standard PET, an image reconstruction algorithm is used to combine these LORs into a final image. This paper presents a new tomographic imaging technique to locate the position of a β + emitting point source without using a standard PET image reconstruction algorithm. The data were collected with a Proof-of-Concept (PoC) PET scanner which has high spatial and energy resolutions. The imaging technique presented in this paper uses events where a gamma undergoes Compton scattering. The positions and energies deposited by the Compton scattered gamma define the surface of a Compton cone (CC) which is the locus of all possible positions of the point source, allowed by the Compton kinematics. The position of the same point source is also located somewhere on the LOR. Therefore, the position of the point source is defined by the 3 gammas and is given by the intersection point of the LOR and the Compton cone inside the Field of View (FOV) of the scanner. We refer to this method as CC×LOR. This new technique can locate the point source with an uncertainty of about 1 mm, after collecting a minimum of 200 CC×LOR events.

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Zhang, Jipeng, Xiong Xiao, Ye Chen, et al. "A Portable Three-Layer Compton Camera for Wide-Energy-Range Gamma-ray Imaging: Design, Simulation and Preliminary Testing." Sensors 23, no. 21 (2023): 8951. http://dx.doi.org/10.3390/s23218951.

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(1) Background: The imaging energy range of a typical Compton camera is limited due to the fact that scattered gamma photons are seldom fully absorbed when the incident energies are above 3 MeV. Further improving the upper energy limit of gamma-ray imaging has important application significance in the active interrogation of special nuclear materials and chemical warfare agents, as well as range verification of proton therapy. (2) Methods: To realize gamma-ray imaging in a wide energy range of 0.3~7 MeV, a principle prototype, named a portable three-layer Compton camera, is developed using the scintillation detector that consists of an silicon photomultiplier array coupled with a Gd3Al2Ga3O12:Ce pixelated scintillator array. Implemented in a list-mode maximum likelihood expectation maximization algorithm, a far-field energy-domain imaging method based on the two interaction events is applied to estimate the initial energy and spatial distribution of gamma-ray sources. The simulation model of the detectors is established based on the Monte Carlo simulation toolkit Geant4. The reconstructed images of a 133Ba, a 137Cs and a 60Co point-like sources have been successfully obtained with our prototype in laboratory tests and compared with simulation studies. (3) Results: The proportion of effective imaging events accounts for about 2%, which allows our prototype to realize the reconstruction of the distribution of a 0.05 μSv/h 137Cs source in 10 s. The angular resolution for resolving two 137Cs point-like sources is 15°. Additional simulated imaging of the 6.13 MeV gamma-rays from 14.1 MeV neutron scattering with water preliminarily demonstrates the imaging capability for high incident energy. (4) Conclusions: We conclude that the prototype has a good imaging performance in a wide energy range (0.3~7 MeV), which shows potential in several MeV gamma-ray imaging applications.

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Li, Hui, and Wenbiao Chen. "Unintended findings: Therapeutic effects of hormones or gamma globulins on Lentiform Fork sign in 3 diabetic uremic patients: Case report/case series." Medicine 102, no. 34 (2023): e34819. http://dx.doi.org/10.1097/md.0000000000034819.

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Introduction: The lentiform fork sign (LFS) is a unique magnetic resonance imaging (MRI) finding characterized by a bright hyperintense rim delineating the lentiform nucleus as a fork associated with metabolic acidosis in end-stage renal disease. Patient concerns: We report 3 cases of LFS in diabetic uremic patients. In one case of uremia, intensive hemodialysis treatment was not effective. Given our poor understanding of LFS, it was regarded as bilateral basal ganglia pathology, and pulse hormone and gamma globulins therapy was initiated. The patient neurological symptoms improved, and the pathological signs on imaging subsided. Based on our experience with the first LFS case, 2 diabetic uremic cases presenting with LFS were successfully treated with hormone or gamma globulin pulse therapy in addition to intensive hemodialysis. Diagnosis: Based on the clinical manifestations, past medical history and MRI imaging changes of the 3 cases reported here, the diagnosis of LFS was established. Interventions: Our experience from these 3 cases suggests that hormone supplementation and gamma globulin therapy may be indicated for treating LFS. Lessons: Our findings highlight that in diabetic uremic dialysis patients with neurological symptoms, LFS should be suspected. The clinical manifestations, past medical history and MRI imaging findings are essential for diagnosing LFS. Hormone supplementation and gamma globulin therapy may be the effective treatment for LFS.

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Wonho Lee and D. K. Wehe. "3-D isotropic imaging of environmental sources using a compact gamma camera." IEEE Transactions on Nuclear Science 51, no. 5 (2004): 2267–72. http://dx.doi.org/10.1109/tns.2004.834714.

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Cervantes, Hernán J., Christianne C. Cavinato, Letícia L. Campos, and Said R. Rabbani. "Gamma Knife® 3-D Dose Distribution Mapping by Magnetic Resonance Imaging." Applied Magnetic Resonance 39, no. 4 (2010): 357–64. http://dx.doi.org/10.1007/s00723-010-0166-4.

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Bower, Geoffrey C. "Millimeter VLBI Observations of the Gamma-Ray Blazar NRAO 530." International Astronomical Union Colloquium 164 (1998): 41–42. http://dx.doi.org/10.1017/s0252921100044432.

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AbstractWe present here 3 epochs of 3 and 7 millimeter wavelength VLBI observations and 2 epochs of lower frequency VLBA imaging of the gamma-ray blazar NRAO 530. These observations document the evolution of the parsec scale jet in this source during the brightest flare in 3 decades. New jet components were created during the flare and are probably related to an increase in gamma-ray activity. The components travel at superluminal velocities, further confirming the connection between superluminal sources and gamma-ray blazars. The rapid evolution of the source makes tracking of components difficult. It appears that either components significantly decelerate or that there is rapid cooling and acceleration of elections. We may be identifying structure due to standing shocks. The jet is bent on all scales between 100 μarcsec to 10 arcsec. The results indicate the ability of 3 mm wavelength imaging to probe the nuclei of blazars rapidly and reliably.

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Watanabe, Yoichi, Chung K. Lee, and Bruce J. Gerbi. "Geometrical accuracy of a 3-tesla magnetic resonance imaging unit in Gamma Knife surgery." Journal of Neurosurgery 105, Supplement (2006): 190–93. http://dx.doi.org/10.3171/sup.2006.105.7.190.

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ObjectThe authors sought to evaluate and improve the geometrical accuracy of a 3-tesla magnetic resonance (MR) imaging unit used for Gamma Knife surgery (GKS).MethodsTo evaluate the geometrical accuracy of a Siemens Magnetom Trio 3-tesla MR imaging unit, two phantoms were used. Both phantoms were imaged with computed tomography (CT), a 1.5-tesla MR imaging unit (Siemens Avanto), and the 3-tesla MR imaging unit. A pair of orthogonal films was obtained with a radiotherapy simulator to validate the spatial coordinates of the marker positions determined with CT. The coordinates of the markers were measured using the GammaPlan treatment planning software. Magnetic resonance imaing was performed using three-dimensional (3D) magnetization-prepared rapid acquisition gradient echo (MPRAGE) and fast low-angle shot sequence (FLASH) pulse sequences. The voxel size was 1 × 1 × 1 mm3.Conclusions The root-mean-square error of MR images was 2 ± 0.73 mm for 3D MPRAGE. The error was reduced to 1.5 ± 0.64 mm for FLASH. The errors were decreased further by applying an image distortion correction method (the field-of-view filter) to the images acquired with FLASH. The mean errors were 1.3 ± 0.39 mm and 1.5 ± 0.77 mm for the two phantoms. The errors increased from 1 mm to 3.1 mm as the measurement points approached the caudal edge of the head coil (larger z value). Proper selection of a pulse sequence together with a geometrical distortion correction improved the geometrical accuracy of MR images. However, further study is needed to increase the geometrical accuracy of 3-tesla MR imaging units for radiosurgical applications.

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