Scott's test Ch 14

  1. What are the 5 types of photon interactions?
    • 1. Incoherent scattering
    • 2. Photoelectric scattering
    • 3. Compton (coherent) scattering
    • 4. Pair Production
    • 5. Photodisintegration
  2. Identify interaction
    The incident photon is low energy
  3. This interaction does not ionize the atom
  4. The incident photon is absorbed in the region
  5. The atom re emits a second photon of same energy as the incident photon, but is headed in new direction
  6. This interaction does not have enough energy to cause release of any electrons
  7. What is the most common interaction
    Compton (incoherent)
  8. Incident photon interacts with outer shell electron
    compton (incoherent0
  9. A loosely bound electron in the  outer shell
    free electron ( valence)
  10. Why is it called a 'free electron'
    because its binding energy is much less than that of the incident photon
  11. During which interaction does the the free electron absorb some of the photons energy and is ejected from the pouter shell making an angle with the direction of the incident photon
    Compton (incoherent)
  12. The photon is scattered from its incident path and has different energy and wavelength than the incident photon
    Compton (incoherent)
  13. what are 3 examples showing the effect of angle on the results of a Compton ( incoherent) interaction?
    • 1. Direct hit on the target atom
    • 2. Grazing hit on the target atom
    • 3. 90 degree scatter
  14. This angle results in the the Compton electron going straight forward carrying away most of the energy with the scattered photon traveling backward with a minimum amount of energy known as 'backscatter'
    Direct hit on the target atom ( compton incoherent)
  15. This angle results in  very little energy loss. Most energy is carried away by scattered photon which will have nearly the same energy as the incident photon
    Grazing hit on the target atom ( compton incoherent)
  16. This angle is important of radiation protection purposes.
    90 degree scatter ( compton incoherent)
  17. The energy of the photon at this angle reaches a maximum of .511MeV and is independent of the energy of the incident photon even at high energies
    90 degree scatter ( compton incoherent)
  18. This interaction occurs at high energies
    pair Production
  19. 1.022 MeV MUST be the energy of the incident photon in order for this interaction to occur
    pair production
  20. The incident photon passes close to the nucleus of the atom
    Pair production
  21. The incident photon is absorbed by the nucleus in this interaction
    pair Production
  22. During this interaction, energy is re emitted as an electron -positron pair β-,β+, which is ejected from the atom
    pair production
  23. The rest energy of the electron- positron pair is_____
    .511MeV each
  24. Electron positron pair production can also occur under the influence of the EM field of the electrons in the target material and is called ____ _______
    triplet production
  25. This interaction involves directly hitting the nucleus of the atom and is absorbed
  26. Energy is absorbed by the atom during which interactions
    • Photodisintegration ( hits nucleus)
    • pair production( passes close to nucleus)
    • Coherent scattering
  27. The sudden absorption of this energy causes the nucleus to emit both neutrons and gamma rays
  28. Mainly occurs in high Z ( atomic number/protons)materials
  29. Unimportant interaction in tissue (low Z)
  30. Extremely important when working with accelerators or machines with hogher than 10MeV
  31. Most radiation therapy energies fall into 1-5MeV
    where this interaction predominates
    Compton (incoherent)
  32. Interaction which occurs below 1MeV
  33. Interaction which occurs above 4.0 MeV
    pair production
  34. when the collision of material leads to excitation and ionization of the atoms,resulting in an interaction of charged particles with the nuclei leading to a radiative energy loss through the process of
  35. Energy in motion through space
  36. When on kinetic energy is lost during a collision it is described as a/an________ collision
  37. When kinetic energy is lost from the system , the collision is ________
  38. What are the 3 types of Electron interactions
    • electron-electron Interactions
    • Elastic Electron-Nuclei Collisions
    • Inelastic Electron-Nuclei Collisions
  39. Brehmsstrahulng occurs during this interaction
    Inelastic Electron-Nuclei Collision
  40. What is the most important method of producing xray beams in therapy units/
Card Set
Scott's test Ch 14
lecture notes