Effects of kilovoltage, milliampere seconds, and focal spot size on image quality

Ma, W; Norton, SR; Hogg, P

Abstract

Purpose 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 kilovolt and milliampere second values using large and small focal spot sizes. Images were displayed on qualitycontrolled
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 kilovolt
(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 kilovolts increase to
within the range of 40 kV to 55 kV, perceptual image quality increases; image quality remains stable after 55 kV.
Discussion This study shows that both large and small focal spot sizes produce images of similar quality, and a wide
range of kilovolt 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.
Conclusion 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 kilovolt and milliampere second values.
Optimization

Citation

Ma, W., Norton, S., & Hogg, P. (2014). Effects of kilovoltage, milliampere seconds, and focal spot size on image quality. Radiologic technology, 85(5), 479-485

• Journal Article Type: Article
• Publication Date: May 1, 2014
• Deposit Date: Apr 1, 2014
• Journal: Radiologic Technology
• Print ISSN: 0033-8397
• Peer Reviewed: Peer Reviewed
• Volume: 85
• Issue: 5
• Pages: 479-485
• Publisher URL: http://www.radiologictechnology.org/content/85/5/479.abstract
• Related Public URLs: http://www.radiologictechnology.org/