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Abdominal CT during pregnancy: a phantom study on the effect of patient centring on conceptus radiation dose and image quality

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Abstract

Objectives

To investigate the effect of patient centring on conceptus radiation dose and image quality in abdominal CT during pregnancy.

Material and methods

Three anthropomorphic phantoms that represent a pregnant woman at the three trimesters of gestation were subjected to a routine abdominal CT. Examinations were performed with fixed mAs (mAsf) and with the automatic exposure control system (AEC) activated. The percent reduction between mAsf and modulated mAs (mAsmod) was calculated. Conceptus dose (Dc) was measured using thermoluminencent dosimeters. To study the effect of misplacement of pregnant women on Dc, each phantom was positioned at various locations relative to gantry isocentre. Image quality was evaluated on the basis of image noise, signal-to-noise ratio, and contrast-to-noise ratio.

Results

The maximum reduction between mAsf and mAsmod was 59.8 %, while the corresponding DC reduction was 59.3 %. DC was found to decrease by up to 25 % and 7.9 % for phantom locations below and above the isocentre, respectively. Image quality deteriorated when AEC was activated, and it was progressively improved from lower to higher than the isocentre locations.

Conclusion

Centring errors do not result in an increase in Dc. To maintain image quality, accurate centring is required.

Key Points

• AEC activation reduces conceptus radiation dose at all gestational stages.

• Patients should be accurately aligned at the gantry isocenter.

• Patient centring deserves increased attention in clinical practice.

• Pregnant patient centring errors do not considerably affect conceptus dose.

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Abbreviations

CT:

Computed tomography

AEC:

Automatic exposure control

mAsf :

Fixed mAs

mAsmod :

Mean modulated mAs

DC :

Conceptus radiation dose

TLD:

Thermoluminesent dosimeters

mAsQR :

Quality reference milliampere sec

HU:

Hounsfield unit

SD:

Standard deviation

ROI:

Region of interest

SNR:

Signal-to-noise ratio

CNR:

Contrast-to-noise ratio

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Acknowledgments

The scientific guarantor of this publication is Prof. John Damilakis. The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article. This study has received funding by the Greek Ministry of Education and Religious affairs, General Secretariat for Research and Technology. No complex statistical methods were necessary for this paper. Institutional review board approval was obtained. The submitted study is not on human subjects. The submitted study is not on animals. No study subjects or cohorts have been previously reported. Methodology: prospective, experimental (phantom study), performed at one institution.

This study was supported by the Greek Ministry of Education and Religious Affairs, General Secretariat for Research and Technology, Operational Program ‘Education and Lifelong Learning’, ARISTIA (Research project: CONCERT).

Author information

Authors and Affiliations

  1. Faculty of Medicine, Department of Medical Physics, University of Crete, Heraklion, P.O. Box 2208, 71003, Crete, Greece

    G. Solomou & J. Damilakis

  2. Department of Medical Physics, University Hospital of Heraklion, Heraklion, P.O. Box 1352, 71110, Crete, Greece

    A. E. Papadakis

Authors
  1. G. Solomou
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  2. A. E. Papadakis
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  3. J. Damilakis
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Correspondence to J. Damilakis.

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Solomou, G., Papadakis, A.E. & Damilakis, J. Abdominal CT during pregnancy: a phantom study on the effect of patient centring on conceptus radiation dose and image quality. Eur Radiol 25, 911–921 (2015). https://doi.org/10.1007/s00330-014-3505-2

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  • DOI: https://doi.org/10.1007/s00330-014-3505-2

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