Ultrasound Physics

1. Anatomic imaging with ultrasound is achieved with the use of ___________ ______________ technique. Pulses of ultrasound are generated and are sent into the patient.

2. The ______________ of each dot on the screen corresponds to the echo’s ___________, which in turn produces a gray scale.

3. ___________ ____________ are vertical parallel lines on the display monitor which are made up of many bright dots that represent echoes from various depths.

4. There are approximately _________ to ________ scan lines that make up a single frame.

5. What are the two types of waves? A) _______________ B) _______________

6. What is the name of the type of wave which can only propagate through a media such as solid, liquid, or gas? _______________

7. What is the name of the type of wave which can propagate through a media or a vacuum? ___________________

8. What is the name of the type of wave that is ultrasound? _______________________

9. A sine wave has two components; draw and label the sine wave include the area of high particle density, and the area of low particle density.

10. There are 3 acoustic variables, what are they? A) _________________ B) _________________

C) _________________

11. Define Frequency (f) and write the 3 formulas.

12. What are the units of Frequency (f).

13. The range of frequencies that we use for ultrasound is between 2MHz-15MHz. We use ________ (High or Low) frequencies to scan deep tissue. We use ________ (High or Low) frequencies to scan shallow tissues.

14. Define Hertz (Hz), (kHz), and (MHz)

15. Define the frequency for the following categories? A) Infrasound or subsonic _____________ B) Audible sound _________________ C) Ultrasound _________________ D) Diagnostic medical ultrasound __________________

16. Define period, (T) and write the formula that relates (T) to (f).

17. What are the units for Period, (T)?

18. If I use a transducer with a frequency of 2.0 MHz what is the period of the Sound wave?

19. If I have a sound wave with a 5 second period, what is the frequency?

20. Define Wavelength, (λ). Write the formula for (λ). 21. What are the Units for wavelength, (λ)? ____________

22. Each medium has a set or fixed speed for sound propagation, much like a speed limit. What are the prop. Speed for the following media? A) Air _________ B) Lung ______________ C) Fat ____________ D) Soft Tissue _____________ E) Bone ________________ F) Muscle _____________

23. Define Propagation speed.

24. What is the formula for Prop. Speed? C = 25. What are the units for Prop. Speed? _________________

26. If the time it take to complete one cycle was found to be 50us, What would be its wavelength?

27. What two properties determine Prop speed for a media?

28. If I have a transducer with a frequency of 5 MHz and a wavelength of 5mm, what is the prop speed?

29. If I have a frequency of 7 MHz and a prop speed of 1.450 mm/us what is the wavelength of the ultrasound?

30. If I have a period of 10 microseconds (us) and a wavelength of 15 mm what is the prop speed? (Hint, what is the relationship between period and frequency?

31. How are density and Propagation speed related? a) Increasing density = ____________ Prop speed b) Decreasing density = ____________ Prop speed

32. How are stiffness and Propagation speed related? a) Increasing stiffness = _____________ Prop speed b) Decreasing stiffness = _____________ Prop speed

33. Define Density.

34. Define Stiffness.

35. Define Harmonics, and what are the first 5 harmonics of a 2.5 MHz transducer?

36. Define PWD

37. Define CWD

38. What are the key differences between PWD and CWD?

39. Draw a 2-pulse system with 4 cycle each, label all the parts with the given choices.

A) PRP

B) PD

C) Lt

D) Period (T)

E) Wavelength (λ)

F) SPL

G) Amplitude

H) Peak to Peak Amplitude

40. Define PRP. What is its formula? What are its Units?

41. Define PRF. What is its formula? What are its units?

42. Define PD. What is its formula? What are its units?

43. Define Lt. What is its formula? What are its units?

44. Define Period (T). What is its formula? What are its units?

45. Define DF. What is its formula? What are its unit

46. Define Spatial Pulse Length, (SPL). What is its formula? What are its units?

47. Define Bandwidth, (BW). What is its formula? The shorter the pulse, the __________ (wider or narrower) the bandwidth.

48. Define quality factor. What is its formula? The ____________ (Lower or higher) numerical value for Qfactor the higher the quality of the transducer.

49. If I have a sound wave with 4cycles, the period is 2us and the listening time is 10us, and the wavelength was 2mm, please calculate the following.

A) PRP =

B) PRF =

C) PD =

D) Lt =

E) T = 10

F) λ =

G) SPL =

H) DF =

50. If I have a sound wave with 2cycles, the pulse duration is 18us and the listening time is 12us, and the spatial pulse length was 8mm, please calculate the following.

A) PRP =

B) PRF =

C) PD =

D) Lt =

E) T = 11

F) λ =

G) SPL =

H) DF =

51. Define Bandwidth, (BW). What is its formula? The shorter the pulse, the __________ (wider or narrower) the bandwidth.

52. Define quality factor. What is its formula? The ____________ (Lower or higher) numerical value for Qfactor the higher the quality of the transducer.

53. What if Fractional Bandwidth? What is its formula?