US Physics Chapter 15

Question 1

What does a scan converter dO?

Answer 1

Takes the multiple spokes of ultrasound input and converts into format for digital display

Question 2

What does read magnification vs write mag look like?

Answer 2

Sonographer selects portion of image and original date blown up ROI not rescanned and pixelated.
US rescans only region of interest.

Question 3

Describe coded excitation

Answer 3

Sophisticated way to improve image quality. In which a very long pulse with multiple frequencies are included. Have to decode at the end. You get better s/N improved resolution, deeper penetration

Question 4

What is spatial compounding and why

Answer 4

Sound waves from several angles are combined to form a single image. Eliminates shadowing from baby ribs.

Question 5

What is frequency compounding and why

Answer 5

Reduces speckle artifact. Takes broad range of frequencies and then looks at multiple sub-bands. It then subtracts out noise and combines signal

Question 6

Whats another name of temporal compounding

Answer 6

persistence or temporal averaging

Question 7

What is temporal compounding

Answer 7

multiple previous frames superimposed. Works best w/ slowly moving structures.

Question 8

what is fill-in interpolation

Answer 8

With sector imaging gaps between beams are wider deeper. Computer programs predict gray scale between beams and fill in.