title: CT radiation profile width measurement using CR imaging plate raw data.
abstract: This technical note demonstrates computed tomography (CT) radiation profile measurement using computed radiography (CR) imaging plate raw data showing it is possible to perform the CT collimation width measurement using a single scan without saturating the imaging plate. Previously described methods require careful adjustments to the CR reader settings in order to avoid signal clipping in the CR processed image. CT radiation profile measurements were taken as part of routine quality control on 14 CT scanners from four vendors. CR cassettes were placed on the CT scanner bed, raised to isocenter, and leveled. Axial scans were taken at all available collimations, advancing the cassette for each scan. The CR plates were processed and raw CR data were analyzed using MATLAB scripts to measure collimation widths. The raw data approach was compared with previously established methodology. The quality control analysis scripts are released as open source using creative commons licensing. A log-linear relationship was found between raw pixel value and air kerma, and raw data collimation width measurements were in agreement with CR-processed, bit-reduced data, using previously described methodology. The raw data approach, with intrinsically wider dynamic range, allows improved measurement flexibility and precision. As a result, we demonstrate a methodology for CT collimation width measurements using a single CT scan and without the need for CR scanning parameter adjustments which is more convenient for routine quality control work.
authors.affiliation: Interior Health, University of British Columbia and University of British Columbia Okanagan. thor.bjarnason@coolth.ca.
authors.forename: Thorarin Albert
authors.initials: TA
authors.lastname: Bjarnason
authors.forename: Chang-Ying Joseph
authors.initials: CY
authors.lastname: Yang
mesh_terms: D006801:Humans; D011786:Quality Control; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D012984:Software; D015898:Tomography Scanners, X-Ray Computed / Q000592:standards / Q000706:statistics & numerical data*; D014057:Tomography, X-Ray Computed / Q000592:standards / Q000706:statistics & numerical data*