Computed tomography (CT) image quality is described in terms of contrast, spatial resolution, image noise and artifact.
Visualisation of certain intra-abdominal structures with CT may be limited by noise, and is therefore closely associated with radiation dose; the higher the radiation dose contributing to the image, the less apparent is image noise and the easier it is to perceive low-contrast structures .
Radiation dose is dependent on tube current, slice scan time and tube peak kilovoltage. A relatively recent innovation, aimed at facilitating dose reduction,...
Description of activity and work performed
The mA ceiling for modulation was increased from 280mA to 400mA for the LP CT AP protocol (120kV, 0.5second rotation, noise index 41, 50% iterative reconstruction).
An increased saline bolus at the time of image acquisition was instituted to assist in improving contrast resolution.
Dose length product (DLP) prior to and after protocol adjustment was measured for 56 patients using dose tracking software.
Both objective and subjective (utilising a predetermined five-point scale) image quality assessments were conducted.
GraphPad was used for statistical analysis.
Conclusion and recommendations
Protocol changes for LP produces a 34.6% dose increase with a small improvement in SNR and CNR. Improved modulation helps ensure more consistent CT image quality is achieved.
S. Joyce; Cork/IE - nothing to disclose M. O'connell; Cork/IE - nothing to disclose B. Carey; Cork/IE - nothing to disclose B. Harte; Cork/IE - nothing to disclose J. McCullagh; Cork/IE - nothing to disclose N. Moore; Cork/IE - nothing to disclose M. F. M. McEntee; Cork/IE - nothing to disclose M. A. Maher; Cork/IE - nothing to disclose O. O'connor; Cork/IE - nothing to disclose
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