Achieving high-resolution, soft-tissue imaging with cone-beam CT: A two-pronged approach for modulation of x-ray fluence and detector gain

S. A. Graham, J. H. Siewerdsen, D. J. Moseley, H. Keller, N. A. Shkumat, D. A. Jaffray

Research output: Contribution to journalConference articlepeer-review


Cone-beam computed tomography (CBCT) presents a highly promising and challenging advanced application of flat-panel detectors (FPDs). The great advantage of this adaptable technology is in the potential for sub-mm 3D spatial resolution in combination with soft-tissue detectability. While the former is achieved naturally by CBCT systems incorporating modern FPD designs (e.g., 200-400 um pixel pitch), the latter presents a significant challenge due to limitations in FPD dynamic range, large field of view, and elevated levels of x-ray scatter in typical CBCT configurations. We are investigating a two-pronged strategy to maximizing soft-tissue detectability in CBCT: 1.) front-end solutions, including novel beam modulation designs (viz., spatially varying compensators) that alleviate detector dynamic range requirements, reduce x-ray scatter, and better distribute imaging dose in a manner suited to soft-tissue visualization throughout the field of view; and 2.) back-end solutions, including implementation of an advanced FPD design (Varian PaxScan 4030CB) that features dual-gain and dynamic gain switching that effectively extends detector dynamic range to 18 bits. These strategies are explored quantitatively on CBCT imaging platforms developed in our laboratory, including a dedicated CBCT bench and a mobile isocentric C-arm (Siemens PowerMobil). Pre-clinical evaluation of improved soft-tissue visibility was carried out in phantom and patient imaging with the C-arm device. Incorporation of these strategies begin to reveal the full potential of CBCT for soft-tissue visualization, an essential step in realizing broad utility of this adaptable technology for diagnostic and image-guided procedures.

Original languageEnglish (US)
Article number25
Pages (from-to)198-206
Number of pages9
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Issue numberI
StatePublished - 2005
Externally publishedYes
EventMedical Imaging 2005 - Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 13 2005Feb 15 2005


  • Bow-tie
  • C-arm
  • Cone-beam CT
  • Contrast-to-noise
  • Dose
  • Dual-gain
  • Dynamic range
  • Flat panel
  • Scatter

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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