Determination of effective energies in CT calibration

Michael R. Millner, William H. Payne, Robert G. Waggener, William D. McDavid, Michael J. Dennis, Victor J. Sank

Research output: Contribution to journalLetterpeer-review

30 Scopus citations

Abstract

The effective energy of a polychromatic beam for a Computed Tomography (CT) scanner can be measured directly only with difficulty. However, a linear relationship exists between the measured CT numbers and corresponding attenuation coefficients of known materials at the effective energy of the x-ray beam. The effective energy can then be determined by searching all energies for the best linear correlation between the CT numbers and the attenuation coefficients. This can be performed by two methods: graphically, by means of choosing visually the straightest of the fitted lines or, mathematically, by maximizing the correlation coefficient. The energy corresponding to the optimal fit is therefore selected as the effective energy. The latter method was implemented by computer and demonstrated by scanning the AAPM phantom, which contained known materials, and determining the effective energies and the relationship between the linear attenuation coefficients and CT numbers for three commercial units.

Original languageEnglish (US)
Pages (from-to)543-545
Number of pages3
JournalMedical Physics
Volume5
Issue number6
DOIs
StatePublished - Nov 1978

Keywords

  • CALIBRATION
  • CAT SCANNING
  • DIAGNOSTIC TECHNIQUES
  • ELECTRONIC EQUIPMENT
  • PHANTOMS
  • TOMOGRAPHY
  • X-RADIATION
  • X-RAY TRANSMISSION SCANNING

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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