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10. PROCESSING
Images received from the Digital Detector are displayed on the monitor as raw images immediately
after acquisition. Raw images are low contrast. After acquisition, a number of calculations are applied
to the image to create the processed image, which replaces the raw image on the screen.
Note that both processed and raw images are saved. The raw images are saved in the DICOM MG
"for processing" format so that processing can be carried out later if required, perhaps using a
hospital-specific algorithm. The processed images are saved in the DICOM MG "for presentation"
format, ready for review.
The main calculations that can be applied to create the processed image are:
D Collimator Detection. This applies a black mask around the useful image area, covering areas
which would otherwise be white. It allows more comfortable viewing.
D Pseudo-log Transformation. This facilitates the manipulation of brightness and contrast during the
review. After the transformation the image dynamic range is reduced to 12 bits, without loss of
clinical information.
D Thickness Equalization or Premium View . If the Premium View option is not present or is not
enabled in medical preferences (see Chapter 7 Browser, section 8-3 Medical Application
preferences), Thickness Equalization is applied. If the Premium View option is present and
enabled, Premium View is applied:
– Thickness Equalization. Subcutaneous tissues can be difficult to see on the screen because of
monitor display limitations. This is corrected by applying a thickness equalization algorithm to
decrease the image dynamic range. Image information beyond a threshold level of gray,
selected to correspond to subcutaneous tissues, is modified for more visibility. The end result is
clear visibility of the medical information in all regions of the breast. When this algorithm is
used, the processing description applied is referred to as Proc 1.
The Thickness Equalization algorithm is not applied to the following images:
– Magnified, Spot and Collimated views.
– Images in which the breast tissue covers 100% of the digital detector panel area.
– Images with certain combinations of manually selected parameters.
The processing description applied to these images, when the thickness equalization
algorithm is not used, is referred to as Proc 0.
– Premium View (option). This is an image processing algorithm which increases the visibility of
breast structures. The main advantage is to provide a single breast image in which the contrast
in the fatty tissues is similar to that obtained by setting WW (window width) and WL (window
level) for optimum visualization of fatty tissues, and the contrast in the fibro-glandular tissue is
similar to that obtained by setting WW and WL for optimal visualization of fibro-glandular
tissues. The Premium View algorithm also includes a thickness equalization algorithm to
enhance the visibility of subcutaneous tissues.
Under certain specific conditions (e.g. particular exposure techniques) the Premium View
algorithm cannot be applied.
Note:
Premium View is an image processing algorithm optimized for the structure of breast
images.
– When imaging an object with thick or sharp borders (e.g., a phantom), you may see
an enhanced brightness at the border of the object. This enhancement is normal
and is not expected to affect correct phantom scoring.
Senographe 2000 D Acquisition System
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OM 5179217–1–100
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