Automatic tube-current modulation in CT—a comparison between different solutions

In this study, tube-current modulation systems on two different CT equipments have been evaluated: Care Dose from Siemens and Auto mA from GE Medical Systems. Care Dose modulates the tube current in the xy-plane during rotation whereas Auto mA modulates the tube current in the z-direction. xy-Plane...

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Bibliographic Details
Published in:Radiation protection dosimetry 2005-01, Vol.114 (1-3), p.308-312
Main Author: Nilsson, Jonas
Format: Article
Language:English
Subjects:
Humans
Ions
MEDICIN
MEDICINE
Methylmethacrylate
Phantoms, Imaging
Radiation Dosage
Radiographic Image Enhancement - methods
Radiographic Image Interpretation, Computer-Assisted - methods
Radiography, Abdominal
Radiometry
Tomography, X-Ray Computed - methods
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Summary:In this study, tube-current modulation systems on two different CT equipments have been evaluated: Care Dose from Siemens and Auto mA from GE Medical Systems. Care Dose modulates the tube current in the xy-plane during rotation whereas Auto mA modulates the tube current in the z-direction. xy-Plane modulation was investigated by using an elliptic Polymethylmethacrylate phantom and a CTDI–ion chamber. To investigate modulation in the z-direction, an anthropomorphic dosimetry phantom (Atom) was used. Tests performed with and without tube-current modulation were compared with respect to absorbed dose and image quality. In the anthropomorphic phantom measurements, the dose savings were 15% using Care Dose and the photon starvation artefacts were negligible. Using Auto mA the absorbed dose depends on the chosen noise level. Image noise becomes more constant throughout the patient but photon starvation artefacts remain. We conclude that the two tube-current modulation techniques show different dose advantages and image quality artefacts.
ISSN:0144-8420
1742-3406
1742-3406
DOI:10.1093/rpd/nch501