Patient Interactions

1. Patient Interactions

2. Patient Interactions • Review Tube Interaction • Heat • Brems • Characteristic • Patient Interactions • Classic Coherent • Compton • Photoelectric • Pair Production • Photodisintegration • Why These are Important? • Image Production • Patient/Tech Safety

3. Patient Interactions • Review of Tube Interactions: • Heat • Brems • Characteristic

4. Heat

5. Brems

6. Characteristic

7. Patient Interactions • Review Tube Interaction • Heat • Brems • Characteristic • Patient Interactions • Classic Coherent • Compton • Photoelectric • Pair Production • Photodisintegration • Why These are Important? • Image Production • Patient/Tech Safety

8. Patient Interactions Interaction in the body begin at the atomic level Atoms Molecules Cells Tissues Organs

9. No interaction: X-ray passes completely and get to image receptor Complete absorption: no x-rays get to image receptor Partial absorption with scatter-some x-rays get to image receptor but some get scattered Patient InteractionsInteractions of X-rays with matter

10. Patient Interactions What happens to our Primary Beam?

11. EM Interactions with Matter Patient Interactions General interactions with matter include: • Scatter • With or without partial absorption • Absorption • Full attenuation

12. Patient Interactions X-ray photons can change cells

13. Some radiations are energetic enough to rearrange atoms in materials through which they pass, and can therefore he hazardous to living tissue. 1913

14. Some radiations are energetic enough to rearrange atoms in materials through which they pass, and can therefore he hazardous to living tissue. Hiroshima victim

15. Patient Interactions I don’t want that to happen to me!!

16. Patient Interactions

17. Classical (Coherent) Patient Interactions

18. Patient Interactions Classical (Coherent) Scattering • Excitation of the total complement of atomic electrons occurs as a result of interaction with the incident photon • No ionization takes place • Electrons in shells “vibrate” • Small heat is released • The photon is scattered in different directions • Energies below 10kV

19. Patient Interactions Classical (Coherent) Classical scattering

20. Classical (Coherent) Patient Interactions • Net Result of Classical • No energy transfer • Photon changes direction with same energy • Occurs with LOW ENERGY photons • No ionization • Not diagnostic

21. Patient Interactions Compton scattering • COMPTON SCATTERING • Outer shell electron in body • Interacts with x-ray photon from the tube • 3. Moderate energy electron

22. Patient Interactions Compton scattering Recoil electron can produce another interaction if high enough energy. Compton scattering does not provide any useful diagnostic information.

23. Patient Interactions Compton scattering compton scattering (effect)

24. Patient Interactions Compton scattering • Moderate energy x-ray photon ejects an outer shell electron. • Energy is divided between scattered photon and the Compton electron (ejected e- or recoil electron) • Scattered photon has sufficient energy to exit body. • Since the scattered photon exits the body, it does not pose a radiation hazard to the patient. • Can increase film fog (reduces contrast) • Radiation hazard to personnel

25. Patient Interactions Photoelectric effect photoelectron Incoming photon interacts with inner shell electron. The “knocked-out” electron is called a photoelectron. The energy of the incoming photon is absorbed.

26. Patient Interactions Photoelectric effect photoelectric interaction

27. Patient Interactions Photoelectric effect CASCADE

28. Patient Interactions Photoelectric effect • Moderate energy x-ray photon ejects inner shell electron (energy absorbed) • Leaves an orbital vacancy, releasing a photoelectron. (As vacancy is filled, another photon is produced-scatter radiation ) • More likely to occur in absorbers of high atomic number (bone, positive contrast media) • Contributes significantly to patient dose, • As all the photon energy is absorbed by the patient , this is responsible for the production of short-scale contrast.

29. Patient Interactions Pair production Electron (Negatron) positron

30. Patient Interactions Pair Production

31. Pair Production Very High Energy Photon…..MkV Not used in Diagnostic X-ray

32. photodisintegration Patient Interactions Nuclear fragment

33. Patient Interactions Photodisintegration

34. Photodisintegration Very High Energy Photon…..MkV Not used in Diagnostic X-ray

35. Patient Interactions Summary of Interactions • Classical Coherent • Low energy photons • No diagnostic effect • Contributes to scatter • Compton Effect (Scattering) • Moderate energy photons • No diagnostic effect • Contributes to scattering • Contributes to personnel dose • Photoelectric Effect • Moderate energy photons • Definite diagnostic effect • Contributes to image contrast • Atomic number dependent • Contributes to patient dose • Pair Production • High energy photons • Not useful in diagnostic range • Photodisintegration • High energy photons • Not useful in diagnostic range

37. What kind of interaction is this?

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39. What kind of interaction is this?

40. What kind of interaction is this?

41. What kind of interaction is this?

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43. What kind of interaction is this?

44. Things to Remember About X-ray Interactions with Matter

45. Things to Remember About Diagnostic Radiation Production

46. Patient Interactions • Review Tube Interaction • Heat • Brems • Characteristic • Patient Interactions • Classic Coherent • Compton • Photoelectric • Pair Production • Photodisintegration • Why These are Important? • Image Production • Patient/Tech Safety

47. Summary of Interactions

48. Summary of Interactions summary of interactions

49. Why Interactions are Important? Image production

50. Biggest Contributor to Personnel Hazard