Measurements of air kerma index in computed tomography: A comparison among methodologies

Appl Radiat Isot. 2018 Aug;138:10-13. doi: 10.1016/j.apradiso.2017.10.008. Epub 2017 Oct 5.


As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. In this work, dosimetry in CT beams was carried out in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber, thermoluminescent (TL) detectors and radiochromic film. Calibration results showed the low energy dependence of all three dosimetric systems for the 100-120kV range, the very high uncertainty of the TL dosimeters in comparison to the other systems and high nonlinearity response in terms of air kerma of the radiochromic film. Measurements with the three systems in a 120kV CT protocol showed an acceptable agreement among the weighted air kerma index values, but TL dosimeters presented the highest uncertainties in the values.

Keywords: Air kerma CT index; CT dosimetric systems; CT dosimetry.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Film Dosimetry / methods
  • Film Dosimetry / statistics & numerical data
  • Humans
  • Phantoms, Imaging
  • Radiometry / instrumentation
  • Radiometry / methods*
  • Radiometry / statistics & numerical data
  • Thermoluminescent Dosimetry / methods
  • Thermoluminescent Dosimetry / statistics & numerical data
  • Tomography, X-Ray Computed*
  • X-Ray Film