title: Evaluation of a corrected implementation of a method of simulating pulmonary nodules in chest tomosynthesis.
abstract: Background A method of simulating pulmonary nodules in tomosynthesis images has previously been developed and evaluated. An unknown feature of a rounding function included in the computer code was later found to introduce an artifact, affecting simulated nodules in low-signal regions of the images. The computer code has now been corrected. Purpose To perform a thorough evaluation of the corrected nodule-simulation method, comparing the detection rate and visual appearance of artificial nodules with those of real nodules in an observer performance experiment. Material and Methods A cohort of 64 patients with a total of 129 pulmonary nodules was used in the study. Artificial nodules, each matching a corresponding real nodule by size, attenuation, and anatomical location, were generated and simulated into the tomosynthesis images of the different patients. The detection rate and visual appearance of artificial nodules generated using both the corrected and uncorrected computer code were compared to those of real nodules. The results were evaluated using modified receiver operating characteristic (ROC) analyses. Results The difference in detection rate between artificial and real nodules slightly increased using the corrected computer code (uncorrected code: area under the curve [AUC], 0.47; 95% CI, 0.43-0.51; corrected code: AUC, 0.42; 95% CI, 0.38-0.46). The visual appearance was however substantially improved using the corrected computer code (uncorrected code: AUC, 0.70; 95% CI, 0.63-0.76; corrected code: AUC, 0.49; 95% CI, 0.29-0.65). Conclusion The computer code including a correct rounding function generates simulated nodules that are more visually realistic than simulated nodules generated using the uncorrected computer code, but have a slightly different detection rate compared to real nodules.
authors.affiliation: 1 Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Sweden.
authors.forename: Frida
authors.initials: F
authors.lastname: Svensson
authors.affiliation: 2 Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden.
authors.forename: Christina
authors.initials: C
authors.lastname: Söderman
authors.affiliation: 1 Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Sweden.|2 Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden.
authors.forename: Angelica
authors.initials: A
authors.lastname: Svalkvist
authors.affiliation: 3 Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden.|4 Department of Radiology, Sahlgrenska University Hospital, Sweden.
authors.forename: Rauni
authors.initials: R
authors.lastname: Rossi Norrlund
authors.affiliation: 3 Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden.|4 Department of Radiology, Sahlgrenska University Hospital, Sweden.
authors.forename: Jenny
authors.initials: J
authors.lastname: Vikgren
authors.affiliation: 3 Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden.|4 Department of Radiology, Sahlgrenska University Hospital, Sweden.
authors.forename: Åse Allansdotter
authors.initials: ÅA
authors.lastname: Johnsson
authors.affiliation: 1 Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Sweden.|2 Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Båth
mesh_terms: D019540:Area Under Curve; D016477:Artifacts; D003198:Computer Simulation; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D055613:Multiple Pulmonary Nodules / Q000000981:diagnostic imaging*; D012372:ROC Curve; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Lung; adults; digital radiography; observer performance; technology assessments; thorax