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Image artifacts degrade digital radiography performance
Category : CR/DR
New forms of image artifacts can compromise the performance of digital radiography (DR) equipment, say researchers from the Mayo Clinic in Rochester, MN. The group described its experience with DR artifacts and how to correct for them. Artifacts featured in the Mayo paper were produced by flat-panel DR detectors with an amorphous silicon thin-film transistor array, coupled to a phosphor layer of either cesium iodide or gadolinium oxysulfide. Specific equipment models in the study included DRX-1 from Carestream Health, Definium 8000 from GE Healthcare, DigitalDiagnost from Philips Healthcare, and Axiom Aristos MX from Siemens Healthcare.
In an interview with, Walz-Flannigan discussed the implications of image lag artifact, a problem linked to DR detector design, and backscatter artifact, an issue primarily associated with inadequate radiation shielding for wireless digital detectors. Artifacts due to image lag (also referred to as ghosting) have raised safety concerns. Walz-Flannigan pointed to instances where the shadows of lead laterality markers positioned on a patient during an earlier procedure reappear as artifacts on subsequent images. Ghosting seems to arise from an inability to deactivate detector plate phosphors that were energized on a completed image before later image acquisitions are performed. The trapped charges produce a double exposure, making the next image in a series either difficult or impossible to read. Picture 1 shows outline of the patient's neckline and lead marker from a swimmer’s view of a shoulder study overlap (with inverse opacity) in this lumbar spine image taken two minutes later. The most visible artifact is directly posterior to the lumbar spine. The second picture demonstrate how backscatter artifact expressed itself as an outline of DR system electronics imposed on high-exposure images of large patients or long exposures. (All images courtesy of Alisa Walz-Flannigan, PhD.)
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Modify Date: 29-07-2012
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