b) Scans

c) ultrasound A-scan and B-scan

A-scan

• transducer sends ultrasound pulses through the body

• pulses are partly reflected and partly transmitted at boundaries

• the reflected pulse is received at the transducer

• it has less energy than the original pulse

  • some is transmitted

  • some is dissipated into the body

• computer plots a voltage against time graph for the reflected pulses

B-scan

• transducer sends ultrasound pulses through the body

• pulses are partly reflected and partly transmitted at boundaries

• the reflected pulse is received at the transducer

• it has less energy than the original pulse

  • some is transmitted

  • some is dissipated into the body

• computer produces a row of dots

• one dot → represents the the boundary between two tissues

• brightness of a dot → proportional to the intensity of the reflected pulse