title: Phantom-based quality assurance measurements in B-mode ultrasound.
abstract: BACKGROUND
  Recommended phantom-based quality assurance measurements in B-mode ultrasound (US) may be tedious. For the purpose of cost-effective US quality assurance it is important to evaluate measurements that effectively reflect the quality of US scanner.
  
  
  OBJECTIVE
  To find out which recommended phantom-based quality assurance measurements are effective in detecting dead or weak transducer elements or channels in US scanners when visual image analysis and manual measurements are used.
  
  
  METHODS
  Altogether 66 transducers from 33 US scanners were measured using a general purpose phantom and a transducer tester. The measurements were divided into two groups. Group I consisted of phantom-based uniformity measurement, imaging the air with a clean transducer (air image) and measuring the transducer with the transducer tester, and group II of phantom-based measurements of depth of penetration, beam profile, near field, axial and lateral resolution, and vertical and horizontal distance accuracy. The group II measurements were compared to group I measurements.
  
  
  RESULTS
  With group I measurements, the results with 20% of the transducers were found defective. With 35% of the transducers the results were considered defective in group II measurements. Concurrent flaws in both groups were found with 11% of the transducers.
  
  
  CONCLUSIONS
  Phantom-based measurements of depth of penetration, beam profile, near field, axial and lateral resolution, and vertical and horizontal distance accuracy did not consistently detect dead or weak transducer elements or channels in US scanners.
authors.affiliation: HUS Helsinki Medical Imaging Center, Helsinki University Central Hospital, Helsinki, Finland ; Department of Physics, University of Helsinki, Helsinki, Finland.
authors.forename: Vilma
authors.initials: V
authors.lastname: Mannila
authors.affiliation: HUS Helsinki Medical Imaging Center, Helsinki University Central Hospital, Helsinki, Finland ; Department of Physics, University of Helsinki, Helsinki, Finland.
authors.forename: Outi
authors.initials: O
authors.lastname: Sipilä
keywords: Ultrasound; acceptance testing; quality assurance; quality control