title: Evaluating the impact of scan settings on automatic tube current modulation in CT using a novel phantom.
abstract: OBJECTIVE
  The aim of this study was to make a comprehensive evaluation of how variable scan settings can affect the performance of automatic tube current modulation (ATCM) in recent CT scanners from the four major manufacturers.
  
  
  METHODS
  A phantom was designed and manufactured for the purpose of evaluating ATCM. The phantom was scanned with four categories of systematically varied settings (scan projection radiograph, technique and reconstruction parameters and phantom miscentring). The performance of ATCM, in terms of applied tube current and noise uniformity, for the scans with varied settings was compared with a reference scan using subjective and quantitative approaches.
  
  
  RESULTS
  The ATCM implemented by each manufacturer is based on different principles and any affect to the performance of the ATCM, when varying scan settings, will manifest differently among the vendors. The results are summarized in four tables corresponding to the categories of varied settings.
  
  
  CONCLUSIONS
  The developed phantom proved useful for evaluating the ATCM. It is important to understand how different implementations (vendor specific) of ATCM perform in order to make informed decisions about the selection of scan settings when designing protocols. The resulting tables can serve as a reference for understanding the different implementations of ATCM and highlight settings that should be taken into consideration when adjusting an imaging protocol. Advances in knowledge: The results from this work can serve as a reference for how changes in geometry or scan settings can affect the performance of ATCM, in terms of tube current and noise.
authors.affiliation: 1 Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.
authors.forename: Deborah
authors.initials: D
authors.lastname: Merzan
authors.affiliation: 1 Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.
authors.forename: Patrik
authors.initials: P
authors.lastname: Nowik
authors.affiliation: 1 Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.
authors.forename: Gavin
authors.initials: G
authors.lastname: Poludniowski
authors.affiliation: 1 Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.|2 Department of Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden.
authors.forename: Robert
authors.initials: R
authors.lastname: Bujila
mesh_terms: D001331:Automation / Q000295:instrumentation*; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D011874:Radiometry / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*