title: Evaluation of accuracy and precision of manual size measurements in chest tomosynthesis using simulated pulmonary nodules.
abstract: OBJECTIVE
  To investigate the accuracy and precision of pulmonary nodule size measurements on chest tomosynthesis images.
  
  
  METHODS
  Artificial ellipsoid-shaped nodules with known sizes were inserted in clinical chest tomosynthesis images. The volume of the nodules corresponded to that of a sphere with a diameter of 4.0, 8.0, or 12.0 mm. Four thoracic radiologists were given the task to determine the longest diameter of the nodules. All nodules were measured twice. Measurement accuracy in terms of the mean measurement error was determined. Intraobserver and interobserver variabilities, as well as variability because of differences between nodules and their locations, were used as measures of precision.
  
  
  RESULTS
  The mean measurement error ranged from -0.3 to 0.1 mm for the nodule size groups and observers. Of the smallest nodules, the observers found 7-17 of total 50 nodules nonmeasurable. The intraobserver and interobserver variabilities were of similar magnitude, indicating relatively small differences between the observers. The internodule variability was in general larger, indicating that the different characteristics of the nodules and their location are sources of variability.
  
  
  CONCLUSIONS
  The results suggest a high accuracy and precision for manual measurements of the nodules in chest tomosynthesis images. However, small nodules (<5.0 mm) may be difficult to measure at all because of poor visibility.
authors.affiliation: Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE-41345 Gothenburg, Sweden. Electronic address: christina.e.soderman@vgregion.se.
authors.forename: Christina
authors.initials: C
authors.lastname: Söderman
authors.affiliation: Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Åse A
authors.initials: ÅA
authors.lastname: Johnsson
authors.affiliation: Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Jenny
authors.initials: J
authors.lastname: Vikgren
authors.affiliation: Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Rauni R
authors.initials: RR
authors.lastname: Norrlund
authors.affiliation: Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: David
authors.initials: D
authors.lastname: Molnar
authors.affiliation: Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Angelica
authors.initials: A
authors.lastname: Svalkvist
authors.affiliation: Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE-41345 Gothenburg, Sweden; Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Lars G
authors.initials: LG
authors.lastname: Månsson
authors.affiliation: Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE-41345 Gothenburg, Sweden; Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Båth
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D015588:Observer Variation; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Thoracic radiography; dimensional measurement accuracy; observer variation; solitary pulmonary nodule; tomosynthesis