A prototype coded aperture detector for small animal SPECT

In a previous simulation study, we demonstrated the feasibility of using coded apertures together with pixelated detectors tors for small animal SPECT. In this paper; we further explore the potential of this approach with a prototype detector and simulated multipinhole apertures. We also investigate...

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Bibliographic Details
Published in:	IEEE transactions on nuclear science 2002-10, Vol.49 (5), p.2167-2171
Main Authors:	Meikle, S.R., Kench, P., Weisenberger, A.G., Wojcik, R., Smith, M.F., Majewski, S., Eberl, S., Fulton, R.R., Rosenfeld, A.B., Fulham, M.J.
Format:	Article
Language:	eng
Subjects:	60 APPLIED LIFE SCIENCES ANIMALS APERTURES Convergence Detectors Image reconstruction PERFORMANCE TESTING PHOTOMULTIPLIERS Prototypes Sensor arrays SIGNAL-TO-NOISE RATIO SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY SPATIAL RESOLUTION Virtual prototyping
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Summary:	In a previous simulation study, we demonstrated the feasibility of using coded apertures together with pixelated detectors tors for small animal SPECT. In this paper; we further explore the potential of this approach with a prototype detector and simulated multipinhole apertures. We also investigated the effect of multiplexing due to overlapped projections on convergence properties, image signal-to-noise ratio (SNR) and spatial resolution. The detector comprises a 48/spl times/44 array of NaI(Tl) crystals, each 1 mm/spl times/1 mm/spl times/5 mm on a 1.25-mm pitch. The crystal array is directly coupled to a Hamamatsu R3941 8 cm position sensitive photomultiplier tube. Multipinhole apertures were simulated by performing repeated SPECT acquisitions of the same object with a single tungsten pinhole translated to different positions in the aperture plane. Image reconstruction is based on a three-dimensional ray driven projector which is an extension of a method described for single pinhole SPECT with a displaced center of rotation. Image estimates are updated using the maximum likelihood expectation maximization (ML-EM) algorithm. The effect of multiplexing was to slow convergence and reduce the achievable SNR by approximately 15% compared with nonmultiplexed data (but the result may be achieved in a fraction of the time). The reconstructed resolution obtained with a resolution phantom was 1.5-mm full width at half maximum and there was no appreciable difference between the resolution of multiplexed and nonmultiplexed data. These results encourage us to develop a prototype coded aperture system for high sensitivity, high resolution small animal SPECT.
ISSN:	0018-9499 1558-1578