Chapter Twelve: Two-Dimensional Imaging

What makes a better lateral resolution?

narrow sound beam

What shape does the mechanical transducer produce?

fan or sector shape

How is the beam steered in a mechanical transducer?

mechanical

What kind of focusing does a mechanical transducer use?

fixed

What happens to the image with a damaged crystal in the mechanical transducer?

entire image is destroyed

How many crystals does the mechanical transducer have?

one

What are the three channel components?

active element, wire, and system electronics

What is the linear arrangement?

crystals are in a straight line

What is the annular arrangement?

crystals are ring shaped

What is the convex arrangement?

crystals are in an arch

What image shape does the linear phased array transducer produce?

fan or sector

What type of steering is used in linear phased array transducers?

electronic

What type of focusing is used in linear phased array transducers?

electronic

What happens with a damaged crystal in a linear phased array transducer?

erratic beam steering and focusing

What does a slope mean?

steered

What does a curvature mean?

focusing

What transducer has a disc like crystal arrangement?

annular phased array transducers

What type of steering is used in annular phased array transducers?

mechanical

What type of focusing is used in annular phased array transducers?

electronic

What image shape does the annular phased array transducer produce?

sector or fan

What happens when a crystal malfunctions in a annular phased array transducer?

horizontal drop out

How many rectangular elements are in a linear switched or sequential array transducer?

120-250

What is the width of the rectangular elements in a linear switched or sequential array transducer?

1 wavelength

How are the crystals arranged in a linear switched or sequential array transducer?

side by side in a line

What type of steering is used in a linear switched or sequential array transducer?

electronic

What type of focusing is used in a linear switched or sequential array transducer?

electronic

What image shaped does a linear switched or sequential phased array transducer produce?

rectangular or parallelogram

What happens with a damaged crystal in a linear switched or sequential array transducer?

vertical drop out

What type of image shape does the convex array transducer produce?

blunted sector

What type of steering does the convex array transducer use?

electronic

What type of focusing does the convex array transducer use?

electronic

What happens with a crystal malfunction in a convex array transducer?

vertical drop out

What type of focusing does a vector array transducer use?

electronic

What type of steering does a vector array transducer use?

electronic

What image shape does the vector array transducer produce?

trapezoidal

What is elevation resolution also known as?

slice thickness

What is elevation resolution determined by?

imaging plane thickness

What makes a better elevation resolution?

thin beams

What transducers have best elevational resolution?

mechanical and annular phased array transducers

In disc shaped crystal elevation resolution is equivalent to what?

lateral resolution

In new transducers what is the dimension of arrays?

1 ½ with approximately 700 crystals

What transducer produce side lobes?

single element transdcers

What transducers produce grating lobes?

array transducers

What do lobes decrease?

decrease image quality and lateral resolution

How do we fix lobes?

adopization and subdicing

What is the diameter of a beam referred to on the board exam?

aperture

What does aperture improve?

improves lateral resolution