Tackling the commissioning of a digital radiography AEC system

Abstract

AEC devices aim to maintain a consistent level of clinical image quality despite variations in patient body habitus and imaging method. The assessment of AEC performance has undergone significant revision with the advent of digital radiography and challenges still remain. Verification of manufacturers’ target detector air kerma (DAK) values with differing AEC testing protocols can be problematic, particularly when the system has been configured with integrated direct digital radiography (DDR) detectors. In addition, there is a need for comparative dose information from current DDR technology to be made available to the wider Medical Physics community. AEC testing was performed on 4 recently-installed Carestream DRX Evolution Plus digital radiographic systems as part of their commissioning tests. AEC calibration was assessed using 3 IPEM-recommended parameters; DAK, image pixel value and detector dose indicator (DDI). Testing was performed with both free and scatter-free configurations and with and without antiscatter grid. A mixture of exit dose and in-bucky measurements were performed with the assistance of a field service engineer (FSE) for both free and integrated detectors. Results from the AEC testing of the four Carestream digital radiographic systems are presented for different testing conditions along with hints and tips on assessing the AEC dose levels when commissioning the systems. DAK results are compared to the manufacturers target values and to Bowden et al.’s (2011) published results on other DDR systems. These results could be used as initial AEC reference values against which others can compare their results when commissioning comparable systems.