Poster — Thur Eve — 02: Measurement of CT radiation profile width using Fuji CR imaging plate raw data

Authors

  • Bjarnason T A,

    1. Diagnostic Imaging Services, Interior Health, Kelowna, Canada
    2. Department of Radiology, University of British Columbia, Vancouver, Canada
    3. Sindi Ahluwalia Hawkins Centre for the Southern Interior, British Columbia Cancer Agency, Kelowna, Canada
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  • Yang C J

    1. Diagnostic Imaging Services, Interior Health, Kelowna, Canada
    2. Department of Radiology, University of British Columbia, Vancouver, Canada
    3. Sindi Ahluwalia Hawkins Centre for the Southern Interior, British Columbia Cancer Agency, Kelowna, Canada
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Abstract

Measuring the CT collimation width and assessing the shape of the overall profile is a relatively straightforward quality control (QC) measure that impacts both image quality and patient dose, and is often required at acceptance and routine testing. Most CT facilities have access to computed radiography (CR) systems, so performing CT collimation profile assessments using CR plates requires no additional equipment. Previous studies have shown how to effectively use CR plates to measure the radiation profile width. However, a major limitation of the previous work is that the full dynamic range of CR detector plates are not used, since the CR processing technology reduces the dynamic range of the DICOM output to 210, requiring the sensitivity and latitude settings of CR reader to be adjusted to prevent clipping of the CT profile data. Such adjustments to CR readers unnecessarily complicate the QC procedure. These clipping artefacts hinder the ability to accurately assess CT collimation width because the full-width at half maximum value of the penumbras are not properly determined if the maximum dose of the profile is not available. Furthermore, any inconsistencies in the radiation profile shape are lost if the profile plateau is clipped off. In this work we developed an opensource Matlab script for straightforward CT profile width measurements using raw CR data that also allows assessment of the profile shape without clipping, and applied this approach during CT QC.

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