放射線器材學（包括磁振學與超音波學）題庫下載題庫

Spatial Compounding

Spatial compounding is another example of preprocessing. It is a technique in which scan lines are directed in multiple directions by phasing so that structures are interrogated more than once by the ultrasound beam (Figure 4-49). Averaging sequential frames spatially, as many as nine typically, improves the quality of the image in several ways:

• As in persistence (which is temporal averaging), speckle is reduced.

• Clutter caused by artifacts is reduced.

• Smooth (specular) surfaces are presented more completely because they are interrogated at more than one angle, in...

Spatial Compounding

Spatial compounding is another example of preprocessing. It is a technique in which scan lines are directed in multiple directions by phasing so that structures are interrogated more than once by the ultrasound beam (Figure 4-49). Averaging sequential frames spatially, as many as nine typically, improves the quality of the image in several ways:

• As in persistence (which is temporal averaging), speckle is reduced.

• Clutter caused by artifacts is reduced.

• Smooth (specular) surfaces are presented more completely because they are interrogated at more than one angle, increasing the probability that close to 90-degree incidence is achieved (which is necessary to receive echoes from them).

• Structures previously hidden beneath highly attenuating objects can be visualized.