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Author  |
Brown, J.M.C.; Dimmock, M.R.; Gillam, J.E.; Paganin, D.M. |
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Title |
A low energy bound atomic electron Compton scattering model for Geant4 |
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Journal Article |
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Year |
2014 |
Publication |
Nuclear Instruments & Methods in Physics Research B |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. B |
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Volume |
338 |
Issue |
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Pages |
77-88 |
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Keywords |
Compton scattering; Geant4; Radiation transport modelling; Monte Carlo method |
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Abstract |
A two-body fully relativistic three-dimensional scattering framework has been utilised to develop an alternative Compton scattering computational model to those adapted from Ribberfors' work for Monte Carlo modelling of Compton scattering. Using a theoretical foundation that ensures the conservation of energy and momentum in the relativistic impulse approximation, this new model, the Monash University Compton scattering model, develops energy and directional algorithms for both the scattered photon and ejected Compton electron from first principles. The Monash University Compton scattering model was developed to address the limitation of the Compton electron directionality algorithms of other computational models adapted from Ribberfors' work. Here the development of the Monash University Compton scattering model, including its implementation in a Geant4 low energy electromagnetic physics class, G4LowEPComptonModel, is outlined. Assessment of the performance of G4LowEPComptonModel was undertaken in two steps: (1) comparison with respect to the two standard Compton scattering classes of Geant4 version 9.5, G4LivermoreComptonModel and G4PenelopeComptonModel, and (2) experimental comparison with respect to Compton electron kinetic energy spectra obtained from the Compton scattering of 662 key photons off the K-shell of gold. Both studies illustrate that the Monash University Compton scattering model, and in turn G4LowEPComptonModel, is a viable replacement for the majority of computational models that have been adapted from Ribberfors' work. It was also shown that the Monash University Compton scattering model is able to reproduce the Compton scattering triply differential cross-section Compton electron kinetic energy spectra of 662 keV photons K-shell scattering off of gold to within experimental uncertainty. |
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Address |
[Brown, J. M. C.; Paganin, D. M.] Monash Univ, Sch Phys, Clayton, Vic 3800, Australia, Email: jeremy.brown@cern.ch |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0168-583x |
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Notes |
WOS:000343390400012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1973 |
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Author |
Brown, J.M.C.; Gillam, J.E.; Paganin, D.M.; Dimmock, M.R. |
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Title |
Laplacian Erosion: An Image Deblurring Technique for Multi-Plane Gamma-Cameras |
Type |
Journal Article |
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Year |
2013 |
Publication |
IEEE Transactions on Nuclear Science |
Abbreviated Journal |
IEEE Trans. Nucl. Sci. |
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Volume |
60 |
Issue |
5 |
Pages |
3333-3342 |
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Abstract |
Laplacian Erosion, an image deblurring technique for multi-plane Gamma-cameras, has been developed and tested for planar imaging using a GEANT4 Monte Carlo model of the Pixelated Emission Detector for RadioisOtopes (PEDRO) as a test platform. A contrast and Derenzo-like phantom composed of I-125 were both employed to investigate the dependence of detection plane and pinhole geometry on the performance of Laplacian Erosion. Three different pinhole geometries were tested. It was found that, for the test system, the performance of Laplacian Erosion was inversely proportional to the detection plane offset, and directly proportional to the pinhole diameter. All tested pinhole geometries saw a reduction in the level of image blurring associated with the pinhole geometry. However, the reduction in image blurring came at the cost of signal to noise ratio in the image. The application of Laplacian Erosion was shown to reduce the level of image blurring associated with pinhole geometry and improve recovered image quality in multi-plane Gamma-cameras for the targeted radiotracer I-125. |
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ISSN |
0018-9499 |
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Notes |
WOS:000325827200020 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1609 |
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Author |
Nguyen, C.V.; Gillam, J.E.; Brown, J.M.C.; Martin, D.V.; Nikulin, D.A.; Dimmock, M.R. |
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Title |
Towards Optimal Collimator Design for the PEDRO Hybrid Imaging System |
Type |
Journal Article |
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Year |
2011 |
Publication |
IEEE Transactions on Nuclear Science |
Abbreviated Journal |
IEEE Trans. Nucl. Sci. |
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Volume |
58 |
Issue |
3 |
Pages |
639-650 |
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Keywords |
Compton scattering enhancement; multiple pinhole; PEDRO |
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Abstract |
The Pixelated Emission Detector for RadiOisotopes (PEDRO) is a hybrid imaging system designed for the measurement of single photon emission from small animal models. The proof-of-principle device consists of a Compton-camera situated behind a mechanical collimator and is intended to provide optimal detection characteristics over a broad spectral range, from 30 to 511 keV. An automated routine has been developed for the optimization of large-area slits in the outer regions of a collimator which has a central region allocated for pinholes. The optimization was tested with a GEANT4 model of the experimental prototype. The data were blurred with the expected position and energy resolution parameters and a Bayesian interaction ordering algorithm was applied. Images were reconstructed using cone back-projection. The results show that the optimization technique allows the large-area slits to both sample fully and extend the primary field of view (FoV) determined by the pinholes. The slits were found to provide truncation of the back-projected cones of response and also an increase in the success rate of the interaction ordering algorithm. These factors resulted in an increase in the contrast and signal-to-noise ratio of the reconstructed image estimates. Of the two configurations tested, the cylindrical geometry outperformed the square geometry, primarily because of a decrease in artifacts. This was due to isotropic modulation of the cone surfaces, that can be achieved with a circular shape. Also, the cylindrical geometry provided increased sampling of the FoV due to more optimal positioning of the slits. The use of the cylindrical collimator and application of the transmission function in the reconstruction was found to improve the resolution of the system by a factor of 20, as compared to the uncollimated Compton camera. Although this system is designed for small animal imaging, the technique can be applied to any application of single photon imaging. |
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Address |
[Nguyen, Chuong V.; Dimmock, Matthew R.] Monash Univ, Sch Phys, Melbourne, Vic 3800, Australia, Email: chuong.nguyen@monash.edu |
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Publisher |
Ieee-Inst Electrical Electronics Engineers Inc |
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English |
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ISSN |
0018-9499 |
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Notes |
ISI:000291655900008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
650 |
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