The imaging problems associated with portable chest radiography are (A) scattered radiation; (B) the inability of the radiograph to capture all relevant information; and (C) the lack of control over the overall optical density of the resulting image when there is slight over- or underexposure. Additionally, the shorter focus–detector distance results in undesirable, and sometimes misleading, magnification of structures. High kilovoltage techniques cannot be used because portable machines are unable to deliver a sufficiently high kilovoltage, and as the maximum current is limited, long exposure times are needed, increasing movement artefact. CR systems provide solutions to some of the limitations of portable chest radiography by controlling optical density and contrast, but are unable to overcome the problem of scatter. CR systems remain the most widely used portable radiography system.
Portable DR detectors using FDPs with gadoliniumbased scintillators have been available since 2001. Despite this, FDP detectors have not yet been widely adopted because of (A) prohibitive costs, and (B) the hitherto restricted positioning of DR detectors in a portable bedside setting. However, an increasing array of portable DR detectors is now being made available, including those that can be integrated into existing CR cassettes for flexible positioning, and those with wireless transmission capabilities to allow immediate transfer to PACS, which may substantially improve technologists' workflow. Such developments are likely to encourage the uptake of portable DR systems in the near future.
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