Keywords:  Shutter, presentation state

The Presentation State of the images deals with the actual presentation, not with grayscale consistency, and is achieved by the second part of the softcopy imaging pipeline. Image manipulations that do not directly affect the grayscale pixels are included in this section as well as image and screen annotations and the application of shutters.

The presentation state’s first manipulation is the application of a shutter on the image screen. There are two categories of shutters: circular and rectangular.

Circular shutters are typically applied when the outline of a circular image is displayed as white or has another pattern or value distracting to a viewer. Eliminating a white border is important because it impacts the sensitivity of an observer; it is similar to driving with the sun in your eyes and trying to distinguish any details in the road.

A rectangular shutter is important when an image is collimated, by making the beam smaller using lead collimator leafs. Collimation is used for X-ray modalities such as CR and DR to reduce unnecessary radiation and scatter, which can negatively impact the image quality. The shutters also end up as bright white bands at the border of the image.

In some cases, a physician still wants to look at the area obscured by a collimator; therefore, it is important for the shutter to be applied electronically, allowing it to be switched on or off. A technologist typically applies a shutter as part of the QA process.

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