title: Toward standardized quantitative image quality (IQ) assessment in computed tomography (CT): A comprehensive framework for automated and comparative IQ analysis based on ICRU Report 87.
abstract: OBJECTIVE
  Based on the guidelines from "Report 87: Radiation Dose and Image-quality Assessment in Computed Tomography" of the International Commission on Radiation Units and Measurements (ICRU), a software framework for automated quantitative image quality analysis was developed and its usability for a variety of scientific questions demonstrated.
  
  
  METHODS
  The extendable framework currently implements the calculation of the recommended Fourier image quality (IQ) metrics modulation transfer function (MTF) and noise-power spectrum (NPS), and additional IQ quantities such as noise magnitude, CT number accuracy, uniformity across the field-of-view, contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) of simulated lesions for a commercially available cone-beam phantom. Sample image data were acquired with different scan and reconstruction settings on CT systems from different manufacturers.
  
  
  RESULTS
  Spatial resolution is analyzed in terms of edge-spread function, line-spread-function, and MTF. 3D NPS is calculated according to ICRU Report 87, and condensed to 2D and radially averaged 1D representations. Noise magnitude, CT numbers, and uniformity of these quantities are assessed on large samples of ROIs. Low-contrast resolution (CNR, SNR) is quantitatively evaluated as a function of lesion contrast and diameter. Simultaneous automated processing of several image datasets allows for straightforward comparative assessment.
  
  
  CONCLUSIONS
  The presented framework enables systematic, reproducible, automated and time-efficient quantitative IQ analysis. Consistent application of the ICRU guidelines facilitates standardization of quantitative assessment not only for routine quality assurance, but for a number of research questions, e.g. the comparison of different scanner models or acquisition protocols, and the evaluation of new technology or reconstruction methods.
authors.affiliation: Clinic of Diagnostic and Interventional Radiology (DIR), University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Pahn
authors.affiliation: Clinic of Diagnostic and Interventional Radiology (DIR), University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Skornitzke
authors.affiliation: Department of Radiology (E010), German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Schlemmer
authors.affiliation: Clinic of Diagnostic and Interventional Radiology (DIR), University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.affiliation: Clinic of Diagnostic and Interventional Radiology (DIR), University Hospital Heidelberg, Heidelberg, Germany; Department of Radiology (E010), German Cancer Research Center (DKFZ), Heidelberg, Germany. Electronic address: wolfram.stiller@med.uni-heidelberg.de.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Stiller
mesh_terms: D001331:Automation; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003287:Contrast Media / Q000737:chemistry; D001330:Electronic Data Processing; D005583:Fourier Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D015233:Models, Statistical; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D059629:Signal-To-Noise Ratio; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards
chemical_list: D003287:Contrast Media
keywords: Computed tomography (CT); Modulation transfer function (MTF); Noise-power spectrum (NPS); Quantitative image quality assessment