X-ray + Ultrasound

Question 1

What is meant by acoustic impedance

Answer 1

product of density of medium and speed of sound in medium

Question 2

Why acoustic impedance is important when considering reflection of ultrasound at the boundary between 2 media

Answer 2

-difference in acoustic impedance
-determines fraction of incident intensity that is reflected/ amount of reflection

Question 3

Explain the principles behind the use of ultrasound to obtain diagnostic information about structures within the body

Answer 3

-pulse of ultrasound directed into the body
-reflected at boundary between tissues
-reflected pulse is detected and processed
-time for return of echo gives information on depth
-amount of reflection gives information on tissue structures

Question 4

Explain the principles behind the use of X-rays for the imaging internal body structures

Answer 4

-X-ray beam directed through body onto detector plate
-different tissues absorb beam by different amounts
-giving ‘shadow’ image of structures
-sharpness and contrast //give comments worr