sonography: a window into the human body

• what is sound 


  mechanical disturbance though a medium

  uses pulse echo principle
• what is pulse- echo technique

  transducer/probe sends out pulse to tissue, echo comes back to create image
• what are the two principles of operation

  operating principle 1

  operating principle 2
• what is the positional info for operating principle 1

  knowledge of the direction of pulse

  measurement of echo return time
• what does operating principle 1 use

  echo arrival time to determine depth
• what correspondence does operating principle 1 use

  one-to-one correspondence
• how many scan lines are used to create an image in operating principle 1

  multiple
• what is operating principle 2

  doesn't rely on 1-1 correspondence

  several pulses sent though all regions of cross section

  all echo info is collected
• what are is the scan called for two dimensional scan format

  B-scans or gray-scale scans
• what are the image formats

  linear

  sector

  combo
• what is linear used for

  soft tissue, vascular veins/artery
• what is sector used for

  cardiac
• what is combo used for

  use in abdomen and obgyn
• what is linear


  pulses travel in same direction, parallel, rectangular
• what is sector 


  lines scatter
• what is combo 


  pulse start at one starting point and travel in different direction
• what is volume imaging

  3-D

  acquired by many 2-D sections of echo info and then comes together
• what is doppler effect

  change in frequency caused by moving object
• what is doppler used to measure

  tissue motion and blood flow
• what are the 3 doppler presentations

  audible

  color

  spectral
• what is audible 


  usually not used on own

  listen to fetal heart beat, flow of movement
• what is color 


  color-coded, imposed on gray-scale
• what is spectral

  applied to loud speakers