title: Simulation of nodules and diffuse infiltrates in chest radiographs using CT templates.
abstract: A method is proposed to simulate nodules and diffuse infiltrates in chest radiographs. This allows creation of large annotated databases for training of both radiologists and computer aided diagnosis systems. Realistic nodules and diffuse infiltrates were generated from three-dimensional templates segmented from CT data. These templates are rescaled, rotated, projected and superimposed on a radiograph. This method was compared, in an observer study, to a previously published method that simulates pulmonary nodules as perfectly spherical objects. Results show that it is hard for human observers to distinguish real and simulated nodules when using templates (AUC-values do not significantly differ from .5, p > .05 for all observers). The method that produced spherical nodules performed slightly worse (AUC of one observer differs significantly from .5, p = .011). Simulation of diffuse infiltrates is challenging but also feasible (AUC = 0.67 for one observer).
authors.affiliation: Diagnostic Image Analysis Group, Radboud University Nijmegen Medical Centre, The Netherlands.
authors.forename: G J S
authors.initials: GJ
authors.lastname: Litjens
authors.forename: L
authors.initials: L
authors.lastname: Hogeweg
authors.forename: A M R
authors.initials: AM
authors.lastname: Schilham
authors.forename: P A
authors.initials: PA
authors.lastname: de Jong
authors.forename: M A
authors.initials: MA
authors.lastname: Viergever
authors.forename: B
authors.initials: B
authors.lastname: van Ginneken
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008954:Models, Biological; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*