Task-driven tube current modulation and regularization design in computed tomography with penalized-likelihood reconstruction

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Purpose: This work applies task-driven optimization to design CT tube current modulation and directional regularization in penalized-likelihood (PL) reconstruction. The relative performance of modulation schemes commonly adopted for filtered-backprojection (FBP) reconstruction were also evaluated for PL in comparison. Methods: We adopt a task-driven imaging framework that utilizes a patient-specific anatomical model and information of the imaging task to optimize imaging performance in terms of detectability index (d'). This framework leverages a theoretical model based on implicit function theorem and Fourier approximations to predict local spatial resolution and noise characteristics of PL reconstruction as a function of the imaging parameters to be optimized. Tube current modulation was parameterized as a linear combination of Gaussian basis functions, and regularization was based on the design of (directional) pairwise penalty weights for the 8 in-plane neighboring voxels. Detectability was optimized using a covariance matrix adaptation evolutionary strategy algorithm. Task-driven designs were compared to conventional tube current modulation strategies for a Gaussian detection task in an abdomen phantom. Results: The task-driven design yielded the best performance, improving d' by ∼20% over an unmodulated acquisition. Contrary to FBP, PL reconstruction using automatic exposure control and modulation based on minimum variance (in FBP) performed worse than the unmodulated case, decreasing d' by 16% and 9%, respectively. Conclusions: This work shows that conventional tube current modulation schemes suitable for FBP can be suboptimal for PL reconstruction. Thus, the proposed task-driven optimization provides additional opportunities for improved imaging performance and dose reduction beyond that achievable with conventional acquisition and reconstruction.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2016
Subtitle of host publicationPhysics of Medical Imaging
EditorsDespina Kontos, Joseph Y. Lo, Thomas G. Flohr
PublisherSPIE
ISBN (Electronic)9781510600188
DOIs
StatePublished - 2016
EventMedical Imaging 2016: Physics of Medical Imaging - San Diego, United States
Duration: Feb 28 2016Mar 2 2016

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume9783
ISSN (Print)1605-7422

Other

OtherMedical Imaging 2016: Physics of Medical Imaging
CountryUnited States
CitySan Diego
Period2/28/163/2/16

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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  • Cite this

    Gang, G. J., Siewerdsen, J. H., & Stayman, J. W. (2016). Task-driven tube current modulation and regularization design in computed tomography with penalized-likelihood reconstruction. In D. Kontos, J. Y. Lo, & T. G. Flohr (Eds.), Medical Imaging 2016: Physics of Medical Imaging [978324] (Progress in Biomedical Optics and Imaging - Proceedings of SPIE; Vol. 9783). SPIE. https://doi.org/10.1117/12.2216387