Physics questions 4

Homework

MPHY 502 Diagnostic Imaging Physics Part I

Lecture 4

X-Ray Production, X-Ray Tubes and X-Ray Generators

1. Name 4 basic components of X-Ray Production

2. Name 3 stages of X-Ray Production

3. What is the function of the Cathode

4. Electrons fly from where to where in an x-ray tube?

5. What is the inherent filtration of an x-ray tube?

6. Name 5 levels of electron interaction energies

7. Describe Characteristic X-Ray generation

8. What does “W” stand for?

9. What are the K-Shell binding energies of:

a. Tungsten

b. Molybdenum

c. Rhodium

10. What are the K-Shell characteristic energies of common tube targets

a. Tungsten

b. Molybdenum

c. Rhodium

11. What are is differences between the K-Shell binding energy of Tungsten and the K-Shell Characteristic of Tungsten. Explain.

12. What are three components of and x-ray generator?

13. What charge is on the anode?

14. What is Thermionic Emission?

15. What is a focusing cup used for?

16. How can “Grid Bias Voltage” Stop electron flow?

17. What is space charge limited tube current and how is it different from emission limited?

18. Why is heat bad for an anode?

19. Name two types of Anode Configurations

20. What are the functions of the Rotor and the Stator in a rotating anode?

21. What is the anode target range in diagnostic imaging? How does this effect the spot size? Show your mathematical calculations to support your claims.

22. Define SID

23. What is Heal Effect and how can it be used to an advantage?

24. Describe how the focal spot size changes within the imaging Field.

25. Focal spot nominal size of 0.8mm, is it okay if measured it is 0.7mm (better resolution)?

26. What are the technique factors to be used when measuring the fs?

27. How many line pair/mm is a spot size of 0.6mm?

28. What is off focal radiation and what is one way to abate this?

29. What is special about a mammography x-ray tube insert?

30. What is the maximum allowed X-ray housing leakage rate?

31. What is the technique that is used when testing for housing leakage?

32. What are collimator used for?

33. What is the tolerance of collimator blades in terms of SID?

34. What is a collimator light used for and how does it work?

35. How does pulsed Fluoroscopy use grid bias?

36. What are deflections coils used for in CT?

37. What is a flying focus?

38. Name 6 ways to prolong x-ray tube life.

39. Why would one intentionally insert added aluminum to an x-ray beam?

40. If a transformer has a primary voltage of 20 and the number of primary turns is 10, secondary turns are 100 what is the secondary voltage?

41. Name three types of transformers

42. What is an isolation transformer used for?

43. What can be done to a full wave rectifier circuit to smooth out the “ripples”?

44. What is the benefit of a high frequency rectification?

45. How can one achieve less than 2% ripple?

46. What side of a “step-up” transformer does one place the switch?

47. What is a timer used for in and x-ray machine?

48. What is ABC?

49. What is AEC?

50. What is a “Photo Timer”

51. What is a Count Down timer used for?

52. How does one arrive at the Power Rating of an x-ray tube?

53. What considerations are used when deterring what type of x-ray tube to use?

54. How many MHU are 5.7MJ (Show your math)?

55. Explain how Quality, Quantity and Exposure are influenced by Anode tube material, Tube Voltage, Tube Current, Generator wave form and beam filtration.

56. What is the difference between Skin Exposure and Transmitted exposure when increasing the tube voltage by 20%?

57. Is beam exposure proportional to tube current? When does your answer apply?

58. Per 21 CFR 1020.30, How much beam filtration is required at 150kV?

59. Traversing 10cm of tissue 60 kV, tube current of 3.8 mAs and no filtration skin entrance dose is 264 microGy, with 0.2mm Cu + 1mm Pb tube current of 8.8mAs Skin entrance dose is 123 microGy. Output image equivalent signal remains the same. Why?

60. What is the main reason to use a “cleaner” (less percent ripple) generator wave form?

61. Extra Credit: label the un-labeled peak in slide number 9 of Lecture 4