title: A novel physical anthropomorphic breast phantom for 2D and 3D x-ray imaging.
abstract: OBJECTIVE
  Physical phantoms are central to the evaluation of 2D and 3D breast-imaging systems. Currently, available physical phantoms have limitations including unrealistic uniform background structure, large expense, or excessive fabrication time. The purpose of this work is to outline a method for rapidly creating realistic, inexpensive physical anthropomorphic phantoms for use in full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT).
  
  
  METHODS
  The phantom was first modeled using analytical expressions and then discretized into voxels of a specified size. The interior of the breast was divided into glandular and adipose tissue classes using Voronoi segmentation, and additional structures like blood vessels, chest muscle, and ligaments were added. The physical phantom was then fabricated from the virtual model in a slice by slice fashion through inkjet printing, using parchment paper and a radiopaque ink containing 33% (I33%) or 25% (I25%) iohexol by volume. Three types of parchment paper (P1, P2, and P3) were examined. The phantom materials were characterized in terms of their effective linear attenuation coefficients (μeff) using full-field digital mammography (FFDM) and their energy-dependent linear attenuation coefficients (μ(E)) using a spectroscopic energy discriminating detector system. The printing method was further validated on the basis of accuracy, print consistency, and the reproducibility of ink batches.
  
  
  RESULTS
  The μeffof two types of parchment paper were close to that of adipose tissue, with μeff= 0.61 ± 0.05 cm-1for P1, 0.61 ± 0.04 cm-1for P2, and 0.57 ± 0.03 cm-1for adipose tissue. The addition of the iodinated ink increased the effective attenuation to that of glandular tissue, with μeff= 0.89 ± 0.06 cm-1for P1 + I25%and 0.94 ± 0.06 cm-1for P1 + I33%compared to 0.90 ± 0.03 cm-1for glandular tissue. Spectroscopic measurements showed a good match between the parchment paper and reference values for adipose and glandular tissues across photon energies. Good accuracy was found between the model and the printed phantom by comparing a FFDM of the virtual model simulated through Monte Carlo with a real FFDM of the fully printed phantom. High consistency was found over multiple prints, with 3% variability in mean ink signal across various samples. Reproducibility of ink consistency was very high with <1% variation signal from multiple batches of ink. Imaging of the phantom using FFDM and DBT systems showed promising utility for 2D and 3D imaging.
  
  
  CONCLUSIONS
  A novel, realistic breast phantom can be created using an analytically defined breast model and readily available materials. The work provides a method to fabricate any virtual phantom in a manner that is accurate, inexpensive, easily accessible, and can be made with different materials or breast models.
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Diagnostic and Radiological Health, FDA, Silver Spring, MD, 20993, USA.
authors.forename: Lynda C
authors.initials: LC
authors.lastname: Ikejimba
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Diagnostic and Radiological Health, FDA, Silver Spring, MD, 20993, USA.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Graff
authors.affiliation: Department of Mechanical Engineering, Department of Computer Science, Carnegie Mellon University, Pittsburg, PA, 15213, USA.
authors.forename: Shani
authors.initials: S
authors.lastname: Rosenthal
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Diagnostic and Radiological Health, FDA, Silver Spring, MD, 20993, USA.
authors.forename: Andreu
authors.initials: A
authors.lastname: Badal
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Diagnostic and Radiological Health, FDA, Silver Spring, MD, 20993, USA.
authors.forename: Bahaa
authors.initials: B
authors.lastname: Ghammraoui
authors.affiliation: Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Medical Physics Graduate Program, Department of Biomedical Engineering, Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27705, USA.
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Lo
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Diagnostic and Radiological Health, FDA, Silver Spring, MD, 20993, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Glick
mesh_terms: D001940:Breast; D003198:Computer Simulation; D004867:Equipment Design; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation; D008327:Mammography / Q000295:instrumentation*; D008953:Models, Anatomic; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011327:Printing / Q000379:methods; D015203:Reproducibility of Results
keywords: anthropomorphic; breast phantom; iodine; parchment