1. A prototype coded aperture detector for small animal SPECT
- Author
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Meikle, Steven R., Kench, Peter, Weisenberger, Andrew G., Wojcik, Randy, Smith, Mark F., Majewski, Stan, Eberl, Stefan, Fulton, Roger R., Rosenfeld, Anatoly B., and Fulham, Michael J.
- Subjects
SPECT imaging -- Usage ,Multiplexing -- Methods ,Multichannel communication ,Digital multiplexing ,Animal experimentation -- Methods ,Business ,Electronics ,Electronics and electrical industries - Abstract
In a previous simulation study, we demonstrated the feasibility of using coded apertures together with pixelated detectors 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 x 44 array of NaI(TI) crystals, each 1 mm x 1 mm x 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. Index Terms--Coded aperature, iterature reconstruction, single photon emission computed tomography (SPECT), small animal imaging.
- Published
- 2002