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Efficient optimization based on local shift-invariance for adaptive SPECT systems

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Abstract
Adaptive SPECT systems automatically change some of their settings to maximize the image quality for a given subject and purpose. This approach has a lot of potential, and could lead to drastic improvements in performance. In particular, it would be very useful in high resolution pinhole SPECT, where the low sensitivity requires higher radiation doses or longer imaging times compared to other systems. In order to have adaptation in real-time, we need a fast method for optimizing the adaptive settings according to a given figure of merit. This is still a big challenge. Based on previous work, we address in this paper the issue of fast evaluation of image quality and optimization, for a class of adaptive SPECT systems. We evaluate the image quality in a voxel of interest, reconstructed using post- filtered MLEM, with the contrast-to-noise ratio (CNR). The CNR is computed analytically, using an approximation based on the Fisher information matrix and assuming local shift-invariance on the Fisher information matrices per adaptation parameter. We maximize the CNR with a gradient based optimization approach. We then test this method in the optimization of the angular sampling of a single-head SPECT system which rotates around a phantom. In this case, the method proved to be very efficient, and at the same time showed good agreement with previous results in literature and with the outcome from reconstructions.
Keywords
PET, PROJECTIONS, FEASIBILITY, PINHOLE SPECT, RESOLUTION, SINGLE, PENALIZED MAXIMUM-LIKELIHOOD, LIKELIHOOD IMAGE-RECONSTRUCTION, post-filtered MLEM reconstruction, evaluation of image quality, Fisher information matrix, local shift-invariant approximation, optimization, pinhole SPECT, Adaptive imaging, RECOVERY, VARIANCE

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Chicago
da Rocha Vaz Pato, Lara, Stefaan Vandenberghe, and Roel Van Holen. 2012. “Efficient Optimization Based on Local Shift-invariance for Adaptive SPECT Systems.” In IEEE Nuclear Science Symposium Conference Record, ed. B Yu, 2501–2508. IEEE.
APA
da Rocha Vaz Pato, L., Vandenberghe, S., & Van Holen, R. (2012). Efficient optimization based on local shift-invariance for adaptive SPECT systems. In B Yu (Ed.), IEEE Nuclear Science Symposium Conference Record (pp. 2501–2508). Presented at the Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE, IEEE.
Vancouver
1.
da Rocha Vaz Pato L, Vandenberghe S, Van Holen R. Efficient optimization based on local shift-invariance for adaptive SPECT systems. In: Yu B, editor. IEEE Nuclear Science Symposium Conference Record. IEEE; 2012. p. 2501–8.
MLA
da Rocha Vaz Pato, Lara, Stefaan Vandenberghe, and Roel Van Holen. “Efficient Optimization Based on Local Shift-invariance for Adaptive SPECT Systems.” IEEE Nuclear Science Symposium Conference Record. Ed. B Yu. IEEE, 2012. 2501–2508. Print.
@inproceedings{3144529,
  abstract     = {Adaptive SPECT systems automatically change some of their settings to maximize the image quality for a given subject and purpose. This approach has a lot of potential, and could lead to drastic improvements in performance. In particular, it would be very useful in high resolution pinhole SPECT, where the low sensitivity requires higher radiation doses or longer imaging times compared to other systems. In order to have adaptation in real-time, we need a fast method for optimizing the adaptive settings according to a given figure of merit. This is still a big challenge. Based on previous work, we address in this paper the issue of fast evaluation of image quality and optimization, for a class of adaptive SPECT systems. We evaluate the image quality in a voxel of interest, reconstructed using post- filtered MLEM, with the contrast-to-noise ratio (CNR). The CNR is computed analytically, using an approximation based on the Fisher information matrix and assuming local shift-invariance on the Fisher information matrices per adaptation parameter. We maximize the CNR with a gradient based optimization approach. We then test this method in the optimization of the angular sampling of a single-head SPECT system which rotates around a phantom. In this case, the method proved to be very efficient, and at the same time showed good agreement with previous results in literature and with the outcome from reconstructions.},
  author       = {da Rocha Vaz Pato, Lara and Vandenberghe, Stefaan and Van Holen, Roel},
  booktitle    = {IEEE Nuclear Science Symposium Conference Record},
  editor       = {Yu, B},
  isbn         = {9781467320306},
  keyword      = {PET,PROJECTIONS,FEASIBILITY,PINHOLE SPECT,RESOLUTION,SINGLE,PENALIZED MAXIMUM-LIKELIHOOD,LIKELIHOOD IMAGE-RECONSTRUCTION,post-filtered MLEM reconstruction,evaluation of image quality,Fisher information matrix,local shift-invariant approximation,optimization,pinhole SPECT,Adaptive imaging,RECOVERY,VARIANCE},
  language     = {eng},
  location     = {Anaheim, CA, USA},
  pages        = {2501--2508},
  publisher    = {IEEE},
  title        = {Efficient optimization based on local shift-invariance for adaptive SPECT systems},
  year         = {2012},
}

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