title: A novel pre-processing technique for improving image quality in digital breast tomosynthesis.
abstract: OBJECTIVE
  Nonlinear pre-reconstruction processing of the projection data in computed tomography (CT) where accurate recovery of the CT numbers is important for diagnosis is usually discouraged, for such a processing would violate the physics of image formation in CT. However, one can devise a pre-processing step to enhance detectability of lesions in digital breast tomosynthesis (DBT) where accurate recovery of the CT numbers is fundamentally impossible due to the incompleteness of the scanned data. Since the detection of lesions such as micro-calcifications and mass in breasts is the purpose of using DBT, it is justified that a technique producing higher detectability of lesions is a virtue.
  
  
  METHODS
  A histogram modification technique was developed in the projection data domain. Histogram of raw projection data was first divided into two parts: One for the breast projection data and the other for background. Background pixel values were set to a single value that represents the boundary between breast and background. After that, both histogram parts were shifted by an appropriate amount of offset and the histogram-modified projection data were log-transformed. Filtered-backprojection (FBP) algorithm was used for image reconstruction of DBT. To evaluate performance of the proposed method, we computed the detectability index for the reconstructed images from clinically acquired data.
  
  
  RESULTS
  Typical breast border enhancement artifacts were greatly suppressed and the detectability of calcifications and masses was increased by use of the proposed method. Compared to a global threshold-based post-reconstruction processing technique, the proposed method produced images of higher contrast without invoking additional image artifacts.
  
  
  CONCLUSIONS
  In this work, we report a novel pre-processing technique that improves detectability of lesions in DBT and has potential advantages over the global threshold-based post-reconstruction processing technique. The proposed method not only increased the lesion detectability but also reduced typical image artifacts pronounced in conventional FBP-based DBT.
authors.affiliation: Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
authors.forename: Hyeongseok
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
authors.forename: Taewon
authors.initials: T
authors.lastname: Lee
authors.affiliation: Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
authors.forename: Joonpyo
authors.initials: J
authors.lastname: Hong
authors.affiliation: Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
authors.forename: Sohail
authors.initials: S
authors.lastname: Sabir
authors.affiliation: School of Electrical and Electronics Engineering, Chung-Ang University, Seoul, 06974, South Korea.
authors.forename: Jung-Ryun
authors.initials: JR
authors.lastname: Lee
authors.affiliation: Korea Electricity Research Institute, Ansan, 15588, South Korea.
authors.forename: Young Wook
authors.initials: YW
authors.lastname: Choi
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, 05505, Korea.
authors.forename: Hak Hee
authors.initials: HH
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, 05505, Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Chae
authors.affiliation: Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
authors.forename: Seungryong
authors.initials: S
authors.lastname: Cho
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001943:Breast Neoplasms / Q000000981:diagnostic imaging; D002114:Calcinosis / Q000000981:diagnostic imaging; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008327:Mammography / Q000295:instrumentation / Q000379:methods*; D008953:Models, Anatomic; D019047:Phantoms, Imaging
keywords: contrast enhancement; digital breast tomosynthesis; filtered-backprojection; histogram modification; image processing