title: Evolution of spatial resolution in breast CT at UC Davis.
abstract: OBJECTIVE
  Dedicated breast computed tomography (bCT) technology for the purpose of breast cancer screening has been a focus of research at UC Davis since the late 1990s. Previous studies have shown that improvement in spatial resolution characteristics of this modality correlates with greater microcalcification detection, a factor considered a potential limitation of bCT. The aim of this study is to improve spatial resolution as characterized by the modulation transfer function (MTF) via changes in the scanner hardware components and operational schema.
  
  
  METHODS
  Four prototypes of pendant-geometry, cone-beam breast CT scanners were designed and developed spanning three generations of design evolution. To improve the system MTF in each bCT generation, modifications were made to the imaging components (x-ray tube and flat-panel detector), system geometry (source-to-isocenter and detector distance), and image acquisition parameters (technique factors, number of projections, system synchronization scheme, and gantry rotational speed).
  
  
  RESULTS
  Characterization of different generations of bCT systems shows these modifications resulted in a 188% improvement of the limiting MTF properties from the first to second generation and an additional 110% from the second to third. The intrinsic resolution degradation in the azimuthal direction observed in the first generation was corrected by changing the acquisition from continuous to pulsed x-ray acquisition. Utilizing a high resolution detector in the third generation, along with modifications made in system geometry and scan protocol, resulted in a 125% improvement in limiting resolution. An additional 39% improvement was obtained by changing the detector binning mode from 2 × 2 to 1 × 1.
  
  
  CONCLUSIONS
  These results underscore the advancement in spatial resolution characteristics of breast CT technology. The combined use of a pulsed x-ray system, higher resolution flat-panel detector and changing the scanner geometry and image acquisition logic resulted in a significant fourfold improvement in MTF.
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, California 95616.
authors.forename: Peymon M
authors.initials: PM
authors.lastname: Gazi
authors.affiliation: Department of Radiological Sciences, University of Oklahoma Health Sciences Center, 940 N.E. 13th Street, Nicholson Tower, Oklahoma City, Oklahoma 73104.
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Radiology, University of California, Davis Medical Center, 4860 Y Street, Suite 3100 Ellison Building, Sacramento, California 95817.
authors.forename: George W
authors.initials: GW
authors.lastname: Burkett
authors.affiliation: Department of Radiology, University of California, Davis Medical Center, 4860 Y Street, Suite 3100 Ellison Building, Sacramento, California 95817.
authors.forename: Shadi
authors.initials: S
authors.lastname: Aminololama-Shakeri
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, California 95616 and Department of Radiology, University of California, Davis Medical Center, 4860 Y Street, Suite 3100 Ellison Building, Sacramento, California 95817.
authors.forename: J Anthony
authors.initials: JA
authors.lastname: Seibert
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, California 95616 and Department of Radiology, University of California, Davis Medical Center, 4860 Y Street, Suite 3100 Ellison Building, Sacramento, California 95817.
authors.forename: John M
authors.initials: JM
authors.lastname: Boone
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D008327:Mammography / Q000295:instrumentation* / Q000379:methods*; D015898:Tomography Scanners, X-Ray Computed
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