interactions of radiations with matter; Rayleigh scatter,Photoelectric effect and Pair production is discussed. charge particle interaction related slides will be shared soon

1. Presented by
Sehrish Inam

2. Interactions of Radiation
with Matter
Pair Production
Presented by
Sehrish Inam Course Title :
Medical Radiation

3. Contents
Introduction
Rayleigh scattering
Photoelectric effect
Pair production
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4. Introduction
Radiations
 Continuous emission of energy from a source in
the form of subatomic particles or
electromagnetic radiation.
 Example
 Electron
 Proton
 Neutron
 Gamma rays
 X rays
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5. Classification of Radiation
Radiations can be classified on the
basis of
 Origin (nucleus/orbital electron)
 Nature of radiation (particle/wave)
 Source (natural/artificial)
 Chagres (+ve / -ve / no)
 Ionization potential (uv /x /gamma)
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6. Interacting modes of Radiation
Depends upon
 Atomic no. Z
 Energy of radiation
Modes are
 Scattering
 Absorption
 Mass energy conversion
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7. Rayleigh scattering
& Photoelectric
effect
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8. Rayleigh Scattering(Coherent Scattering)
Incident radiation is considered as classical
EM wave
No loss of energy
No phase difference only momentum
transfers.
Probability increase with low energy EMR
and high Z target
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9. 9
Rayleigh Scattering(Coherent Scattering)

10. 10
Rayleigh Scattering(Coherent Scattering)

11. 11
Rayleigh Scattering(Coherent Scattering)

12. 12
Photoelectric Effect

13. Photoelectric Effect
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14. Use
 Diagnostic radiology energy range up to
150kev
 Absorption in bones P.E.E occur in high Z
 Differential absorption gives better information
regarding various structures in human body.
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Photoelectric Effect

15. 15
Photoelectric Effect
Post Photoelectric Effects
 Characteristic radiation
 Absorb in same atom & gives auger electron
 Auger electron
 Due to local absorption of characteristic x-ray
 Disturbs image quality of Xray

16. Pair Production
16
Presented by Sehrish Inam

17. Materialization of EM radiation
Energy threshold is 2m0c2 = 1.022 MeV
Generates electron and positron pair.
Due to nucleus (e-, e+)
Due to atomic electron (e- e+, e-)
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Pair Production
Pair
Triplet

18. Pair & Triplet Production
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19. Pair Production
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Probability depends upon
 Energy of incoming photons
 Z2 of target material
 π = k Z2 log (E)

20. Pair Production
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21. Pair Production
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22. Pair Production
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23. Conclusion
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