EFFECT OF PATIENT SIZE, ANATOMICAL LOCATION AND MODULATION STRENGTH ON DOSE DELIVERED AND IMAGE-QUALITY ON CT EXAMINATION

To study the effect of patient size, anatomical location and modulation strength (MS) on image-quality and delivered dose of CT scans acquired with automatic-exposure-control system (AEC). Four anthropomorphic phantoms (three paediatric and one thin adult) were studied, and normal and obese adults w...

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Bibliographic Details
Published in:Radiation protection dosimetry 2017-12, Vol.177 (4), p.373-381
Main Authors: Greffier, Joël, Larbi, Ahmed, Macri, Francesco, Beregi, Jean-Paul, Pereira, Fabricio
Format: Article
Language:English
Subjects:
Bioengineering
Ecology, environment
Human health and pathology
Imaging
Life Sciences
Nuclear medicine
Santé publique et épidémiologie
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Summary:To study the effect of patient size, anatomical location and modulation strength (MS) on image-quality and delivered dose of CT scans acquired with automatic-exposure-control system (AEC). Four anthropomorphic phantoms (three paediatric and one thin adult) were studied, and normal and obese adults were simulated by placing bolus plates around the adult phantom. Thorax and abdomen-pelvis CT were performed using an AEC system equipped with five possible MS. Modulated tube current (mAsmod) was compared to Reference mAs and image-noise was assessed. Effective-mAs were lower than Reference-mAs for all but the obese phantom. However, reversal points were estimated for an effective diameter of 27.8 cm in thorax and 26.9 cm in abdomen-pelvis scans, beyond which the patterns of MS were inversed. mAsmod were dependent on attenuation differences among distinct anatomical location. Finally, dose delivered was associated to the mAsmod and patient's size, with both affecting image-quality.
ISSN:0144-8420
1742-3406
DOI:10.1093/rpd/ncx055