1. RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY L 7: X Ray beam IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

5. Part 7: X Ray beam Topic 1: Bremsstrahlung production IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

8. Electrons strike the nucleus N N n(E)  E E 1 E 2 E 3 n 1 n 3 n 2 E 1 E 2 E 3 n 1 E 1 n 2 E 2 n 3 E 3  E E max Bremsstrahlung spectrum

10. Bremsstrahlung spectra dN/dE dN/dE (spectral density) E From a “thin” target E E 0 E 0 E 0 = energy of electrons From a “thick” target E = energy of emitted photons

12. Part 7: X Ray beam Topic 2: Characteristic X Rays IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

14. Characteristic X Rays (II)

17. Part 7: X Ray beam Topic 3: X Ray Beam filtration IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

18. What is beam filtration? Absorber placed between Source and object Will preferably absorb the lower energy photons Or absorb parts of spectrum (K-edge filters) 10 15 20 25 30 15 10 5 Energy (keV) Number of photons (arbitrary normalisation) X Ray spectrum at 30 kV for an X Ray tube with a Mo target and a 0.03 mm Mo filter

20. Tube filtration

21. Filtration Change in QUANTITY & Change in QUALITY spectrum shifts to higher energy 1- Spectrum out of anode 2- After window tube housing (INHERENT filtration) 3- After ADDITIONAL filtration

22. Part 7: X Ray beam Topic 4: Scattered radiation IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

26. Anti scatter grid (II) Source of -rays Lead Scattered X Rays Useful X Rays Film and cassette Patient

27. Part 7: X Ray beam Topic 5: Factors affecting X Ray spectrum IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

29. X Ray spectrum: tube current 400 mA 200 mA X Ray Energy (keV) Number of X Rays per unit Energy

30. X Ray spectrum: tube current Change of QUANTITY NO change of quality Effective kV not changed

31. X Ray spectrum: tube potential Change in QUANTITY & Change in QUALITY - spectrum shifts to higher Energy - characteristic lines appear

32. X Ray spectrum: filtration Change in QUANTITY & Change in QUALITY spectrum shifts to higher energy 1- Spectrum out of anode 2- After window tube housing (INHERENT filtration) 3- After ADDITIONAL filtration

33. X Ray spectrum: Target Z Higher Z Lower Z X Ray Energy (keV) Number of X Rays per unit Energy

34. X Ray spectrum: Target Z Three Phase Single Phase X Ray Energy (keV) Number of X Rays per unit Energy