What is edge gradient artifact?

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The edge gradient effect result in streak artifact or shading (both light and dark) arising from irregularly shaped object that have a pronounced difference in density from surrounding structures. A common clinical example is artifacts that result when barium and air lie adjacent to each other in the stomach.

What causes the edge gradient effect in CT?

The exponential edge-gradient effect must arise in any x-ray transmission CT scanner whenever long sharp edges of high contrast are encountered. The effect is non-linear and is due to the interaction of the exponential law of x-ray attenuation and the finite width of the scanning beam in the x-y plane.

What is one way to fix edge gradient artifacts?

Use a beam hardening correction algorithm.
Use thinner slices.
Use diluted contrast agents.

What is aliasing in CT?

Aliasing artifact, otherwise known as undersampling, in CT refers to an error in the accuracy proponent of analog to digital converter (ADC) during image digitization. Image digitization has three distinct steps: scanning, sampling, and quantization.

How do you avoid out of field artifacts?

Preventing this artifact relies on the CT operator ensuring that the body of the patient lies wholly within the scan field or – in the case of the arms – place them up or down depending upon whether the head and neck or chest and body are being scanned.

What is partial volume artifact in CT?

Partial volume artifact occurs when tissues of widely different absorption are encompassed on the same CT voxel producing a beam attenuation proportional to the average value of these tissues.

What is streak artifacts?

Streaking artifact appears as multiple dark streaking bands positioned between two dense objects, for example at the posterior fossa. Streaking may also occur along the long axis of a single high attenuation object.

How do you reduce streak artifact on CT?

Streak artifacts can be reduced using newer reconstruction techniques or metal artifact reduction software. A radiologist can also try scanning at a higher kV in order to get a harder X-ray beam and thus, fewer beam hardening artifacts.

How do beam hardening artifacts appear on a CT image quizlet?

Beam hardening is caused by very dense objects, including metal, in the scan field. A hip prosthesis is made of metal, so it is expected to cause beam hardening artifact. This will appear as dark or light streaks extending from the interface between the tissue and the metal.

What is beam hardening artifact on CT?

Beam Hardening. The most commonly encountered artifact in CT scanning is beam hardening, which causes the edges of an object to appear brighter than the center, even if the material is the same throughout (Fig. 5a).

What are CT artifacts?

Artifacts can seriously degrade the quality of computed tomographic (CT) images, sometimes to the point of making them diagnostically unusable. To optimize image quality, it is necessary to understand why artifacts occur and how they can be prevented or suppressed. CT artifacts originate from a range of sources.

What is the exponential edge gradient effect in CT scan?

What is an example of edge gradient effect?

How to reduce CT scan motion artifacts?

Manufacturers have built features into the CT scan systems to reduce this motion artifacts such as over scan and partial scan modes, software correction, and cardiac gating. Voluntary motion can be reduced or eliminated by adequate preparing the patient for the examination.