title: Characterization of a high-energy in-line phase contrast tomosynthesis prototype.
abstract: OBJECTIVE
  In this research, a high-energy in-line phase contrast tomosynthesis prototype was developed and characterized through quantitative investigations and phantom studies.
  
  
  METHODS
  The prototype system consists of an x-ray source, a motorized rotation stage, and a CMOS detector with a pixel pitch of 0.05 mm. The x-ray source was operated at 120 kVp for this study, and the objects were mounted on the rotation stage 76.2 cm (R1) from the source and 114.3 cm (R2) from the detector. The large air gap between the object and detector guarantees sufficient phase-shift effects. The quantitative evaluation of this prototype included modulation transfer function and noise power spectrum measurements conducted under both projection mode and tomosynthesis mode. Phantom studies were performed including three custom designed phantoms with complex structures: a five-layer bubble wrap phantom, a fishbone phantom, and a chicken breast phantom with embedded fibrils and mass structures extracted from an ACR phantom. In-plane images of the phantoms were acquired to investigate their image qualities through observation, intensity profile plots, edge enhancement evaluations, and/or contrast-to-noise ratio calculations. In addition, the robust phase-attenuation duality (PAD)-based phase retrieval method was applied to tomosynthesis for the first time in this research. It was utilized as a preprocessing method to fully exhibit phase contrast on the angular projection before reconstruction.
  
  
  RESULTS
  The resolution and noise characteristics of this high-energy in-line phase contrast tomosynthesis prototype were successfully investigated and demonstrated. The phantom studies demonstrated that this imaging prototype can successfully remove the structure overlapping in phantom projections, obtain delineate interfaces, and achieve better contrast-to-noise ratio after applying phase retrieval to the angular projections.
  
  
  CONCLUSIONS
  This research successfully demonstrated a high-energy in-line phase contrast tomosynthesis prototype. In addition, the PAD-based method of phase retrieval was combined with tomosynthesis imaging for the first time, which demonstrated its capability in significantly improving the contrast-to-noise ratios in the images.
authors.affiliation: Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019.
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.affiliation: Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35249.
authors.forename: Aimin
authors.initials: A
authors.lastname: Yan
authors.affiliation: Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Li
authors.affiliation: Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019.
authors.forename: Molly D
authors.initials: MD
authors.lastname: Wong
authors.affiliation: Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019.
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
authors.affiliation: Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35249.
authors.forename: Xizeng
authors.initials: X
authors.lastname: Wu
authors.affiliation: Center of Bioengineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000000981:diagnostic imaging; D002645:Chickens; D004867:Equipment Design; D005399:Fishes; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D010969:Plastics; D011859:Radiography; D011871:Radiology / Q000295:instrumentation* / Q000379:methods*; D014965:X-Rays
chemical_list: D010969:Plastics