Addressing quantum noise
Modern fluoroscopy poses significant challenges for digital image processing. Low-dose settings are commonly used today in clinical practice, particularly for children, who are most sensitive to the damaging effects of ionizing radiation. While a reduction in dose is always desirable, these settings inevitably result in images with high quantum noise, which may be difficult for radiologists to read and can result in longer fluoroscopy times.
Dynamic UNIQUE combines noise suppression by temporal averaging (inter-frame) and spatial noise suppression (intra-frame). Temporal averaging, which accumulates the dose of successive frames, results in a depiction of static anatomical structures that mimics high-dose acquisition. However, it may fail in areas of motion. Dynamic UNIQUE suppresses temporal averaging when movement is detected preventing lag and shadowing of moving structures.
In moving regions of the image and if the sequences are very short, Dynamic UNIQUE applies spatial noise suppression. It uses a physical noise model to assess the contrast-to-noise ratio, which allows for structure-adaptive noise suppression within a single frame. The strength of the spatial noise suppression is adapted to the strength of the temporal noise reduction in adjacent areas. As a result, the image noise level is kept consistently low over the entire image.
Reduced noise impression results in improved detail visibility. Anatomical details are preserved in every image, with no artifacts of moving structures, no lag effect and no shadows of catheters, tubes and lines. Radiologists experience less risk to miss important details, leading to more confidence in the diagnosis.