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Patient Interactions

Patient Interactions. 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. Patient Interactions.

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Patient Interactions

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  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

  36. What kind of interaction is this?

  37. What kind of interaction is this? ssss

  38. What kind of interaction is this?

  39. What kind of interaction is this?

  40. What kind of interaction is this?

  41. What kind of interaction is this? ssssssssssssssssssss

  42. What kind of interaction is this?

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

  44. Things to Remember About Diagnostic Radiation Production

  45. 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

  46. Summary of Interactions

  47. Summary of Interactions summary of interactions

  48. Why Interactions are Important? Image production

  49. Biggest Contributor to Personnel Hazard

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