title: Detecting failed elements on phased array ultrasound transducers using the Edinburgh Pipe Phantom.
abstract: OBJECTIVE
  Imaging faults with ultrasound transducers are common. Failed elements on linear and curvilinear array transducers can usually be detected with a simple image uniformity or 'paperclip' test. However, this method is less effective for phased array transducers, commonly used in cardiac imaging. The aim of this study was to assess whether the presence of failed elements could be detected through measurement of the resolution integral (R) using the Edinburgh Pipe Phantom.
  
  
  METHODS
  A 128-element paediatric phased array transducer was studied. Failed elements were simulated using layered polyvinyl chloride (PVC) tape as an attenuator and measurements of resolution integral were carried out for several widths of attenuator.
  
  
  RESULTS
  All widths of attenuator greater than 0.5 mm resulted in a significant reduction in resolution integral and low contrast penetration measurements compared to baseline (p < 0.05).
  
  
  CONCLUSIONS
  Measurements of resolution integral and low contrast penetration both have the potential to be used as straightforward and inexpensive tests to detect failed elements on phased array transducers. Particularly encouraging is the result for low contrast penetration as this is a quick and simple measurement to make and can be performed with many different test objects, thus enabling 'in-the-field' checks.
authors.affiliation: Department of Oncology Physics, Western General Hospital, Edinburgh, UK.
authors.forename: Dan
authors.initials: D
authors.lastname: Welsh
authors.affiliation: Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: Scott
authors.initials: S
authors.lastname: Inglis
authors.affiliation: Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Pye
keywords: Edinburgh Pipe Phantom; Quality assurance; cardiac imaging; image quality; phased-array; resolution integral