title: Doses under automatic exposure control (AEC) for direct digital radiographic (DDR) X-ray systems.
abstract: Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 μGy with the antiscatter grid in place and 4.0 μGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 μGy with the antiscatter grid in place and 5.4 μGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose.
authors.affiliation: Department of Medical Physics and Bioengineering, St James's Hospital, Dublin, Republic of Ireland. lbowden@stjames.ie
authors.forename: Louise
authors.initials: L
authors.lastname: Bowden
authors.forename: Ronan
authors.initials: R
authors.lastname: Faulkner
authors.forename: Conor
authors.initials: C
authors.lastname: Clancy
authors.forename: Aoife
authors.initials: A
authors.lastname: Gallagher
authors.forename: Mark
authors.initials: M
authors.lastname: Devine
authors.forename: Dermot
authors.initials: D
authors.lastname: Gorman
authors.forename: Geraldine
authors.initials: G
authors.lastname: O'Reilly
authors.forename: Anita
authors.initials: A
authors.lastname: Dowling
mesh_terms: D001331:Automation; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000295:instrumentation* / Q000379:methods / Q000592:standards*; D014965:X-Rays