Records |
Author |
Muñoz, E.; Barrientos, L.; Bernabeu, J.; Borja-Lloret, M.; Llosa, G.; Ros, A.; Roser, J.; Oliver, J.F. |
Title ![sorted by Title field, descending order (down)](img/sort_desc.gif) |
A spectral reconstruction algorithm for two-plane Compton cameras |
Type |
Journal Article |
Year |
2020 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
Volume |
65 |
Issue |
2 |
Pages |
025011 - 17pp |
Keywords |
Compton imaging; Compton camera; hadron therapy; image reconstruction |
Abstract |
One factor limiting the current applicability extent of hadron therapy is the lack of a reliable method for real time treatment monitoring. The use of Compton imaging systems as monitors requires the correct reconstruction of the distribution of prompt gamma productions during patient irradiation. In order to extract the maximum information from all the measurable events, we implemented a spectral reconstruction method that assigns to all events a probability of being either partial or total energy depositions. The method, implemented in a list-mode maximum likelihood expectation maximization algorithm, generates a four dimensional image in the joint spatial-spectral domain, in which the voxels containing the emission positions and energies are obtained. The analytical model used for the system response function is also employed to derive an analytical expression for the sensitivity, which is calculated via Monte Carlo integration. The performance of the method is evaluated through reconstruction of various experimental and simulated sources with different spatial and energy distributions. The results show that the proposed method can recover the spectral and spatial information simultaneously, but only under the assumption of ideal measurements. The analysis of the Monte Carlo simulations has led to the identification of two important degradation sources: the mispositioning of the gamma interaction point and the missing energy recorded in the interaction. Both factors are related to the high energy transferred to the recoil electrons, which can travel far from the interaction point and even escape the detector. These effects prevent the direct application of the current method in more realistic scenarios. Nevertheless, experimental point-like sources have been accurately reconstructed and the spatial distributions and spectral emission of complex simulated phantoms can be identified. |
Address |
[Munoz, Enrique; Barrientos, Luis; Bernabeu, Jose; Borja-Lloret, Marina; Llosa, Gabriela; Ros, Ana; Roser, Jorge; Oliver, Josep F.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: Enrique.Munoz@ific.uv.es |
Corporate Author |
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Thesis |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0031-9155 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000520111400001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
no |
Call Number |
IFIC @ pastor @ |
Serial |
4332 |
Permanent link to this record |
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Author |
Bernabeu, J.; Navarro-Salas, J. |
Title ![sorted by Title field, descending order (down)](img/sort_desc.gif) |
A Non-Local Action for Electrodynamics: Duality Symmetry and the Aharonov-Bohm Effect, Revisited |
Type |
Journal Article |
Year |
2019 |
Publication |
Symmetry-Basel |
Abbreviated Journal |
Symmetry-Basel |
Volume |
11 |
Issue |
10 |
Pages |
1191 - 13pp |
Keywords |
non-local action; electrodynamics; electromagnetic duality symmetry; Aharonov-Bohm effect |
Abstract |
A non-local action functional for electrodynamics depending on the electric and magnetic fields, instead of potentials, has been proposed in the literature. In this work we elaborate and improve this proposal. We also use this formalism to confront the electric-magnetic duality symmetry of the electromagnetic field and the Aharonov-Bohm effect, two subtle aspects of electrodynamics that we examine in a novel way. We show how the former can be derived from the simple harmonic oscillator character of vacuum electrodynamics, while also demonstrating how the magnetic version of the latter naturally arises in an explicitly non-local manner. |
Address |
[Bernabeu, Joan] Ludwig Maximilians Univ Munchen, Phys Dept, Theresienstr 37, D-80333 Munich, Germany, Email: Joan.Bernabeu@physik.uni-muenchen.de; |
Corporate Author |
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Thesis |
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Publisher |
Mdpi |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000495457600005 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
4192 |
Permanent link to this record |