How to Reduce Hardware Artifacts on a CAT Scan

Computed tomography (CT), also referred to as a CAT scan, uses X-rays and computers to take multiple images of the inside of the body. CAT scans are noninvasive and provide more detailed images when compared with regular X-rays. Metallic objects on, or inside, an individual during a CAT scan cause distortions, called hardware artifacts, in the image. Individuals are asked to take off all removable metal objects, such as jewelry, before undergoing a CAT scan. Items such as orthopedic screws or dental implants are not removable and require methods to reduce hardware artifacts on the image. The composition of the metal also affects the type of artifacts it produces.

Instructions

• 1

  Increase the X-ray kilovolt peak. Metallic objects are denser than the body tissues being imaged by a CAT scan. They prevent the penetration of the X-ray beams and cause "beam hardening," a distortion that makes the outer edges of an object appear brighter than the remainder of the object in the image. A higher kilovolt peak increases the penetrating ability of the X-ray beam.

• 2

  Increase the tube current setting on a multichannel CT. A higher tube current setting may increase the X-ray beam's penetration of the metal object.

• 3

  Lower the pitch setting on a multichannel CT. Data will be collected multiple times, increasing the likelihood of getting enough data for a good image. A lower pitch setting also reduces the occurrence of a distortion called splay artifacts that appear as rotating propeller blades.

• 4

  Position the individual, when possible, so the X-ray beam will pass through the metal object at its thinnest point. The thicker the metal, the more distortion results.

• 5

  Use a standard or smooth reconstruction filter to facilitate a better image as the data is reconstructed.

• 6

  Reformat the image to reduce metal hardware artifacts. The increased thickness reduces the appearance of the artifacts.

• 7

  Use a surface 3D or volumetric-rendered image. Surface 3D imaging provides a "bigger picture" look, and volumetric-rendered images reduce artifacts by making bone appear semitransparent.

• 8

  Use extended-scale CT and view the images on wide windows. The larger image size provides more detail and makes it easier to identify objects.