Multi-centric clinical implementation of the remote and automated quality control programme for digital imaging in...

The International Atomic Energy Agency (IAEA) has developed a methodology for a remote and automated quality control (QC) programme for digital radiography (DR) units. The purpose of this paper is to report the results of the implementation of the methodology in four hospitals in Malaysia. The IAEA methodology provides multiple image quality metrics by using dedicated software and standard, easily available materials to construct phantoms at a reasonably low cost. Nine QC phantoms were constructed and distributed across these institutions, with data collected daily or weekly analysed using the Python implementation of the Automated Tool for Image Analysis software. Image quality metrics, including signal-difference-to-noise ratio (SDNR), signal-noise ratio (SNR), modulation transfer function (MTF) and detectability index (d') were assessed on 11 digital radiography units from four different manufacturers. The use of diverse imaging protocols resulted in statistically significant differences in all the image quality metrics across the different units. For the processed image protocols, the median SDNR values ranged (12.2-17.5) and (9.1-17.9), respectively and were less affected by the protocol variations compared to SNR values. The d' 0.3 mm ranged (4.8-7.1) and (3.4-6.2), while the d' 4 mm variation ranged (73-115) and (83-130), respectively. The MTF values were strongly correlated between the horizontal and vertical MTFs, as well as between the MTF levels at 10%, 20% and 50%. Across different DR units, there were significant differences in the image quality metrics, mainly due to the different acquisition protocols employed. Clinical protocols have inherent image post-processing that can significantly alter the image quality metrics values compared to the raw image. The IAEA methodology is a useful tool to track the performance of DR units over time. Recommendations for the wider implementation of this methodology would include standardising the acquisition protocol by means of setting a specific QC protocol template to ensure consistency in the image acquisition.