1. X-ray Production

3. kVp KINETIC ENERGY OF ELECTRONS

4. MADE OF TUNGSTEN + 1%-3% THORIUM
CATHODE
MADE OF TUNGSTEN + 1%-3% THORIUM

5. MELTING POINT- 3,410 DEG. CELSIUS
TUNGSTEN
Z # 74
MELTING POINT- 3,410 DEG. CELSIUS

6. THORIUM
Z # 90

7. CATHODE HEATED UP TO AT LEAST 2,200 DEG. CELSIUS
THERMIONIC EMISSION
CATHODE HEATED UP TO AT LEAST 2,200 DEG. CELSIUS

8. ANODE +++++
TUNGSTEN
TARGET

9. TUNGTEN AS TARGET HIGH Z# - 74------EFFICIENCY OF X-RAY PRODUCTION
HIGH MELTING POINT –3,410 ° C– TARGET HEATED TO 2,000 ° C

10. X-RAY PRODUCTION
BREMSSTRAHLUNG RADIATION
CHARACTERISTIC RADIATION

11. BREMSSTRAHLUNG RADIATION
If an incoming free electron gets close to the nucleus of a target atom, the strong electric field of the nucleus will attract the electron, thus changing direction and speed of the electron. The Electron looses energy which will be emitted as an X-ray photon. The energy of this photon will depend on the degree of interaction between nucleus and electron, i.e. the passing distance. Several subsequent interactions between one and the same electron and different nuclei are possible. X-rays originating from this process are called bremsstrahlung. Bemsstrahlung is a German word directly describing the process: "Strahlung" means "radiation", and "Bremse" means "brake

12. Bremsstrahlung Radiation

13. BREMS

14. DIFFERENT DEGREES OF DECCELERATION
X-RAYS
HEAT

15. BREMS RADIATION IS: POLYENERGETIC !
90% OF X-RAYS ARE PRODUCED THROUGH BREMS
INTERACTIONS WHEN KVP APPLIED

16. BREMS EMISSION-CONTINUOUS

17. Characteristic X-rays
The high energy electron can also cause an electron close to the nucleus in a metal atom to be knocked out from its place. This vacancy is filled by an electron further out from the nucleus. The well defined difference in binding energy, characteristic of the material, is emitted as a monoenergetic photon. When detected this X-ray photon gives rise to a characteristic X-ray line in the energy spectrum.

18. Characteristic Radiation
KE OF PROJECTILE ELECTRON > BINDING ENERGYORBITAL ELECTRON

19. CHARACTERISTIC CASCADE

20. OF DIFFERENT SHELL ELECTRONS
TUNGSTEN-74
BINDING ENERGIES
OF DIFFERENT SHELL ELECTRONS
K-70 KEV
L-12 KEV
M-2.8 KEV

21. CHARACTERISTIC X-RAYSL K
70-12 = 58 keV
70-3 = 67 keV M K M
12-3 = 9 keV L

22. TRANSFER OF ELECTRONS BETWEEN OUTER SHELLS RESULTS IN:
HEAT PRODUCTION !

23. EACH CHARACTERISTIC RADIATION ( ex. K TO L TRANSFER) IS:
MONOENERGETIC !
THERE ARE MANY
CHARACTERISTIC RADIATION
PRODUCED IN ONE ATOM
THEREFORE CHARACTERISTIC
RADIATION
IS ALSO POLYENERGETIC !

24. CHARACTERISTIC EMISSION- LESS POLYENERGETIC!

25. X-RAYS PRODUCTION AN INEFFICIENT PROCESS
80 KVP
99.4% HEAT 0.6% X-RAYS

26. % EFFICIENCY OF X-RAY PRODUCTION
% EFFICIENCY= K * Z * kVp
K = 1 * 10-4

27. X-RAY EMISSION
ISOTROPICAL- IN EVERY DIRECTION

28. USEFUL RADIATION – PROJECTED TOWARD THE PATIENT

29. LEAKAGE RADIATION
HOUSING

30. OFF-FOCUS RADIATION
USEFUL
OFF-FOCUS