title: Effects of kilovoltage, milliampere seconds, and focal spot size on image quality.
abstract: OBJECTIVE
  To determine how kilovoltage (kV), milliampere seconds (mAs), and focal spot size affect perceptual image quality using a hand phantom.
  
  
  METHODS
  Using computed radiography, 70 images of a posteroanterior (PA) oblique hand phantom were acquired with different kilovoltage and milliampere second values using large and small focal spot sizes. Images were displayed on quality-controlled monitors with dimmed ambient lighting. The look-up table for hand radiography was used for image display. Five diagnostic radiographers scored each image for perceptual image quality against a reference image using a 5-point Likert scale.
  
  
  RESULTS
  No significant difference in image quality was found between small and large focal spot sizes at different kilovoltage (P = .46) and milliampere second (P = .56) values. As milliampere seconds increase, perceptual image quality increases gradually from 0.4 mAs to 4 mAs, after which perceptual image quality begins to deteriorate. When kilovoltage increases to within the range of 40 kV to 55 kV, perceptual image quality increases; image quality remains stable after 55 kV.
  
  
  CONCLUSIONS
  This study shows that both large and small focal spot sizes produce images of similar quality, and a wide range of kilovoltage and milliampere seconds can be used to produce images of acceptable quality. The implications of these findings include the potential for extending the life of radiography equipment and the potential for reducing the dose patients receive during appendicular examinations.
  
  
  CONCLUSIONS
  Large focal spot size can be used for PA oblique hand imaging without affecting perceptual image quality. Perceptual image quality remains acceptable and stable for a wide range of kilovoltage and milliampere second values. Optimization of these technical factors to achieve image quality is critical to avoiding higher radiation doses than necessary.
authors.forename: Wang
authors.initials: W
authors.lastname: Kei Ma
authors.forename: Peter
authors.initials: P
authors.lastname: Hogg
authors.forename: Sue
authors.initials: S
authors.lastname: Norton
mesh_terms: D006225:Hand / Q000000981:diagnostic imaging*; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000379:methods; D014057:Tomography, X-Ray Computed