European Radiology

, Volume 14, Issue 7, pp 1275–1284 | Cite as

Assessment of a theoretical formalism for dose estimation in CT: an anthropomorphic phantom study

  • G. BrixEmail author
  • U. Lechel
  • R. Veit
  • R. Truckenbrodt
  • G. Stamm
  • E. M. Coppenrath
  • J. Griebel
  • H.-D. Nagel


Dose assessment in computed tomography (CT) is challenging due to the vast variety of CT scanners and imaging protocols in use. In the present study, the accurateness of a theoretical formalism implemented in the PC program CT-EXPO for dose calculation was evaluated by means of phantom measurements. Phantom measurements were performed with four 1-slice, four 4-slice and two 16-slice spiral CT scanners. Firstly, scanner-specific n CTDIw values were measured and compared with the corresponding standard values used for dose calculation. Secondly, effective doses were determined for three CT scans (head, chest and pelvis) performed at each of the ten installations from readings of thermoluminescent dosimeters distributed inside an anthropomorphic Alderson phantom and compared with the corresponding dose values computed with CT-EXPO. Differences between standard and individually measured n CTDIw values were less than 16%. Statistical analysis yielded a highly significant correlation (P<0.001) between calculated and measured effective doses. The systematic and random uncertainty of the dose values calculated using standard n CTDIw values was about −9 and ±11%, respectively. The phantom measurements and model calculations were carried out for a variety of CT scanners and representative scan protocols validate the reliability of the dosimetric formalism considered—at least for patients with a standard body size and a tube voltage of 120 kV selected for the majority of CT scans performed in our study.


Computed tomography Patient exposure Dosimetry Anthropomorphic phantom Scanner matching 



The authors would like to thank the owners and the staff of the ten facilities where the phantom measurements were performed for their excellent collaboration. Furthermore, the support of R. Banckwitz and C. Süß (Siemens AG, Medical Solutions, Forchheim, Germany) is gratefully acknowledged.


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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • G. Brix
    • 1
    Email author
  • U. Lechel
    • 1
  • R. Veit
    • 1
  • R. Truckenbrodt
    • 1
  • G. Stamm
    • 2
  • E. M. Coppenrath
    • 3
  • J. Griebel
    • 1
  • H.-D. Nagel
    • 4
  1. 1.Department of Radiation Protection and Health, Division of Medical Radiation Hygiene and DosimetryFederal Office for Radiation ProtectionNeuherbergGermany
  2. 2.Department of RadiologyHannover Medical SchoolHannoverGermany
  3. 3.Department of RadiologyUniversity of MunichMunichGermany
  4. 4.Department of Science and TechnologyPhilips Medical SystemsHamburgGermany

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