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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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Language |
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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Author |
Dimmock, M.R.; Nikulin, D.A.; Gillam, J.E.; Nguyen, C.V. |
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Title |
An OpenCL Implementation of Pinhole Image Reconstruction |
Type |
Journal Article |
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Year |
2012 |
Publication |
IEEE Transactions on Nuclear Science |
Abbreviated Journal |
IEEE Trans. Nucl. Sci. |
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Volume |
59 |
Issue |
4 |
Pages |
1738-1749 |
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Keywords |
Collimator; GPU; OpenCL; pinhole |
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Abstract |
AC++/OpenCL software platform for emission image reconstruction of data from pinhole cameras has been developed. The software incorporates a new, accurate but computationally costly, probability distribution function for operating on list-mode data from detector stacks. The platform architecture is more general than previous works, supporting advanced models such as arbitrary probability distribution, collimation geometry and detector stack geometry. The software was implemented such that all performance-critical operations occur on OpenCL devices, generally GPUs. The performance of the software is tested on several commodity CPU and GPU devices. |
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Address |
[Dimmock, Matthew R.; Nikulin, Dmitri A.; Nguyen, Chuong V.] Monash Univ, Sch Phys, Melbourne, Vic 3800, Australia, Email: matthew.dimmock@synchrotron.org.au; |
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Publisher |
Ieee-Inst Electrical Electronics Engineers Inc |
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English |
Summary Language |
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ISSN |
0018-9499 |
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Expedition |
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Conference |
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Notes |
WOS:000307893900034 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1145 |
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Author |
Bolle, E.; Casella, C.; Chesi, E.; De Leo, R.; Dissertori, G.; Fanti, V.; Gillam, J.E.; Heller, M.; Joram, C.; Lustermann, W.; Nappi, E.; Oliver, J.F.; Pauss, F.; Rafecas, M.; Rudge, A.; Ruotsalainen, U.; Schinzel, D.; Schneider, T.; Seguinot, J.; Solevi, P.; Stapnes, S.; Tuna, U.; Weilhammer, P. |
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Title |
AX-PET: A novel PET concept with G-APD readout |
Type |
Journal Article |
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Year |
2012 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
695 |
Issue |
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Pages |
129-134 |
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Keywords |
PET; Axial geometry; Geiger-mode Avalanche Photo Diodes (G-APD); SiPM |
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Abstract |
The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 key and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS strips are individually read out using Geiger-mode Avalanche Photo Diodes (G-APDs). The sensitivity of such a detector can be adjusted by changing the number of layers and the resolution is defined by the crystal and strip dimensions. Two AX-PET modules were built and fully characterized in dedicated test set-ups at CERN, with point-like Na-22 sources. Their performance in terms of energy (Renew approximate to 11.8% (FWMH) at 511 key) and spatial resolution was assessed (sigma(axial) approximate to 0.65 mm), both individually and for the two modules in coincidence. Test campaigns at ETH Zurich and at the company AAA allowed the tomographic reconstructions of more complex phantoms validating the 3D reconstruction algorithms. The concept of the AX-PET modules will be presented together with some characterization results. We describe a count rate model which allows to optimize the planing of the tomographic scans. |
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Address |
[Heller, M.; Joram, C.; Schneider, T.; Seguinot, J.] CERN, PH Dept, CH-1211 Geneva, Switzerland, Email: Matthieu.Heller@cern.ch |
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Publisher |
Elsevier Science Bv |
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English |
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Series Volume |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000311469900026 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1236 |
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Author |
Llosa, G.; Barrillon, P.; Barrio, J.; Bisogni, M.G.; Cabello, J.; Del Guerra, A.; Etxebeste, A.; Gillam, J.E.; Lacasta, C.; Oliver, J.F.; Rafecas, M.; Solaz, C.; Stankova, V.; de La Taille, C. |
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Title |
High performance detector head for PET and PET/MR with continuous crystals and SiPMs |
Type |
Journal Article |
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Year |
2013 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
702 |
Issue |
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Pages |
3-5 |
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Keywords |
Monolithic crystals; SiPM; MG-APD; PET; High resolution; Position determination |
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Abstract |
A high resolution PET detector head for small animal PET applications has been developed. The detector is composed of a 12 mm x 12 mm continuous LYSO crystal coupled to a 64-channel monolithic SiPM matrix from FBK-irst. Crystal thicknesses of 5 mm and 10 mm have been tested, both yielding an intrinsic spatial resolution around 0.7 mm FWHM with a position determination algorithm that can also provide depth-of-interaction information. The detectors have been tested in a rotating system that makes it possible to acquire tomographic data and reconstruct images of Na-22 sources. An image reconstruction method specifically adapted for continuous crystals has been employed. The Full Width at Half Maximum measured from a point source reconstructed with ML-EM was 0.7 mm with the 5 mm crystal and 0.8 mm with the 10 mm crystal. |
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Address |
[Llosa, G.; Barrio, J.; Cabello, J.; Etxebeste, A.; Gillam, J. E.; Lacasta, C.; Oliver, J. F.; Rafecas, M.; Solaz, C.; Stankova, V.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia, Spain, Email: gabriela.llosa@ific.uv.es |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Series Editor |
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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 |
0168-9002 |
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:000314682300002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1330 |
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Author |
Gillam, J.E.; Solevi, P.; Oliver, J.F.; Rafecas, M. |
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Title |
Simulated one-pass list-mode: an approach to on-the-fly system matrix calculation |
Type |
Journal Article |
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Year |
2013 |
Publication |
Physics in Medicine and Biology |
Abbreviated Journal |
Phys. Med. Biol. |
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Volume |
58 |
Issue |
7 |
Pages |
2377-2394 |
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Keywords |
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Abstract |
In the development of prototype systems for positron emission tomography a valid and robust image reconstruction algorithm is required. However, prototypes often employ novel detector and system geometries which may change rapidly under optimization. In addition, developing systems generally produce highly granular, or possibly continuous detection domains which require some level of on-the-fly calculation for retention of measurement precision. In this investigation a new method of on-the-fly system matrix calculation is proposed that provides advantages in application to such list-mode systems in terms of flexibility in system modeling. The new method is easily adaptable to complicated system geometries and available computational resources. Detection uncertainty models are used as random number generators to produce ensembles of possible photon trajectories at image reconstruction time for each datum in the measurement list. However, the result of this approach is that the system matrix elements change at each iteration in a non-repetitive manner. The resulting algorithm is considered the simulation of a one-pass list (SOPL) which is generated and the list traversed during image reconstruction. SOPL alters the system matrix in use at each iteration and so behavior within the maximum likelihood-expectation maximization algorithm was investigated. A two-pixel system and a small two dimensional imaging model are used to illustrate the process and quantify aspects of the algorithm. The two-dimensional imaging system showed that, while incurring a penalty in image resolution, in comparison to a non-random equal-computation counterpart, SOPL provides much enhanced noise properties. In addition, enhancement in system matrix quality is straightforward (by increasing the number of samples in the ensemble) so that the resolution penalty can be recovered when desired while retaining improvement in noise properties. Finally the approach is tested and validated against a standard (highly accurate) system matrix using experimental data from a prototype system-the AX-PET. |
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Address |
[Gillam, J. E.; Solevi, P.; Oliver, J. F.; Rafecas, M.] Univ Valencia, CSIC, IFIC, Inst Fis Corpuscular, Valencia, Spain, Email: john.gillam@ific.uv.es |
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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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ISSN |
0031-9155 |
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Notes |
WOS:000316181300024 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1370 |
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