8/26: Production of X-rays II

Question 1

1. The flow of electrons through an electrical conductor

Answer 1

a. Electricity

Question 2

2. The amount of electrons flowing through a conductor per second

Answer 2

a. Current

Question 3

3. What are the units for current?

Answer 3

a. Amperes (A)

Question 4

4. The path of an electrical current

Answer 4

a. Circuit

Question 5

5. The difference in electrical potential energy between two points in an electric circuit. Measure in volts (V)

Answer 5

a. Voltage (potential difference)

Question 6

6. What is the half cycle of electricity?

Answer 6

a. 1/120 of a second

Question 7

7. Describe what happens during each half cycle?

Answer 7

a. 1st: anode = + and attracts electrons from cathode to produce x-radiation
b. 2nd: anode = - and no radiation because no electron attraction

Question 8

8. How many electrical cycles do we get in the USA?

Answer 8

a. 60 cycles per second

Question 9

9. What is a full wave rectification?

Answer 9

a. Allows the current to have constant exposure to produce x-rays. Anode is always attracting electrons

Question 10

10. What is rectification?

Answer 10

a. Changing alternating current to direct

Question 11

11. Describe how electricity flows and produces X-rays in terms of full wave rectification?

Answer 11

a. Changes AC into DC
b. Full wave rectification to get high frequency power supply
c. Essentially constant potential between cathode and anode now
d. Higher energy beam compared to AC

Question 12

12. Why can’t we just use DC straight from the wall instead of changing it from AC → DC?

Answer 12

a. DC doesn’t work with transformers
b. Must be AC to DC for it to work

Question 13

13. What is constant potential and direct current important?

Answer 13

a. Shorter exposure times
b. More consistent beam intensity
c. Higher energy beam
d. Decreased radiation dose

Question 14

14. What are the 2 mechanisms for x-ray formation?

Answer 14

a. Bremsstrahlung radiation
b. Characteristic radiation

Question 15

15. What kind of interaction is bremsstrahlung radiation?

Answer 15

a. Electron to nucleus

Question 16

16. What kind of interaction is characteristic radiation?

Answer 16

a. Electrons interact with the tungsten plate (focal spot). This has enough energy to ionize the tungsten

Question 17

17. How is bremsstrahlung radiation created?

Answer 17

a. Electrons slow or stop at the nucleus and energy is transferred as X-ray radiation

Question 18

18. How is characteristic radiation created?

Answer 18

a. Electrons displace inner shell electrons and make radiation

Question 19

19. In bremsstrahlung radiation, do all electrons attain the same velocity?

Answer 19

No

Question 20

KE =

Answer 20

a. 1/2MV^2

Question 21

21. The higher the velocity, the greater the ____ of electrons

Answer 21

KE

Question 22

22. Bremsstrahlung radiation increases with what?

Answer 22

a. Voltage (kV)
b. atomic number of the target (Z#)

Question 23

23. Bremsstrahlung radiation has what distribution of wavelengths?

Answer 23

a. Wide distribution (heterogenous)

Question 24

24. In what radiation do you have a head-on collision with the nucleus?

Answer 24

a. bremsstrahlung

Question 25

25. In characteristic radiation, atoms become

Answer 25

a. Ionized and unstable

Question 26

26. How is radiation emitted in characteristic radiation?

Answer 26

a. Electron gets displaced and another from outer shell has to fill in and this causes radiation

Question 27

27. What is true about Characteristic radiation?

Answer 27

a. Outer shell electron moves to inner shell

Question 28

28. In characteristic radiation, the energy emitted is equivalent to what?

Answer 28

a. Difference in the binding energies of the 2 shells/orbits

Question 29

29. What percentage of diagnostic x-ray beam is characteristic radiation?

Answer 29

30%

Question 30

30. What percentage of diagnostic x-ray beam is bremsstrahlung radiation?

Answer 30

70%

Question 31

31. Most photons emit what kind of radiation?

Answer 31

a. Bremsstrahlung