1. 1. Basic Of X-Ray ProductionBy : M. Khalis , JKN Johor
2. 2. Atoms All atoms share the same basicstructure. During past 200 years, scientist haveproposed different models.
3. 3. Daltons Model
4. 4. Thomsons Model End of 1800s Thompson discovered that atomswere not simple, solid spheres. Atoms contained subatomic particles.- very small, negatively charged- ELECTRONS
5. 5. Thomsons Model Also knew that atoms were electricallyneutral- Most contain enough positive charge to balance negative charge of electrons. Developed model where electronswere stuck into a positively chargesphere.- Like chipsmore
6. 6. Thomsons Model
7. 7. Rutherfords Model By early 1900s, scientist knew thatpositive charge of atom comes fromsubatomic particles called protons. 1911 Rutherford begins to testtheory His experiment led him to believe thatprotons are concentrated in a smallarea at center of atom. - called this area the nucleus
8. 8. Rutherfords Model Rutherfords model describes an atomas mostly empty space, with a centernucleus that contains nearly all themass.- seperti biji dalam buah rambutan.
9. 9. TRIVIAA hydrogen atom lost its electron andwent to the police station to file amissing electron report. He wasquestioned by the police: "Havent youjust misplaced it somewhere? Are yousure that your electron is really lost?"Im positive." replied the atom.
10. 10. Bohrs Model Modified Rutherfords model in 1913 Proposed that each electron has acertain amount of energy. - Helped electron move aroundnucleus. Electrons move around nucleus inregion called energy levels. Energy levels surround nucleus inrings, like layers of onion
11. 11. Bohrs Model Has been called planetary model- Energy levels occupied by electrons are like orbits of planets at different distances from the sun (nucleus)
12. 12. Electron Cloud Model Model accepted today Electrons dart around in an energylevel Rapid, random motion creates acloud of negative charge aroundnucleus Electron cloud gives atom its size andshape
13. 13. Electron Cloud Model
14. 14. Objective Review x-ray production requirements X-ray tube interactions X-ray emission spectrum
15. 15. Productions Of X-RayRequirements: a source of fast moving electrons must be a sudden stop of the electrons motion in stopping the electron motion, kinetic energy (KE) is converted to EMS energies Infrared (heat), light & x-ray energies
16. 16. Productions Of X-Ray Power is sent to x-ray tube via cables mA (milliamperage) is sent to filamenton cathode side. Filament heats up electrons boil off Negative charge
17. 17. Productions Of X-Ray Positive voltage (kVp) is applied toANODE Negative electrons = attracted acrossthe tube to the positive ANODE. Electrons slam into anode suddenly stopped. X-RAY PHOTONS ARE CREATED
18. 18. Productions Of X-Ray Electronbeam is focused from the cathode to the anode target by the focusing cup Electronsinteract with the electrons on the tungsten atoms of target material PHOTONS sent through the window PORT towards the patient
19. 19. QUIZ C B
20. 20. Principles Part Of X-RayImaging System Operating Console High-voltage generator X-ray tube The system is designed to provide alarge number of e- with high kineticenergy focused to a small target
21. 21. QUIZ 2 Projectilee- interacts with the orbital e- of the target atom. This interaction results in the conversion of e- ___ energy into ________ energy and ________ energy.
22. 22. Tube Interaction3 possible tube interactions Tube interactions are generated from _____ slamming into ________? Heat (99%), EM energy as infraredradiation (heat) & x-rays (1%) X-rays = Characteristic (20%) or Bremsstrahlung (80%)
23. 23. Heat Mostkinetic energy of projectile e- is converted into heat 99% Projectilee- interact with the outer- shell e- of the target atoms but do not transfer enough energy to the outer- shell e- to ionize
24. 24. Heat is an excitationrather than an ionization
25. 25. Heat Production Production of heat in the anodeincreases directly with increasing x-ray tube current & kVp Doubling the x-ray tube currentdoubles the heat produced Increasing kVp will also increase heatproduction
26. 26. Bremsstrahlung Radiation Heat& Characteristic produces EM energy by e- interacting with tungsten atoms e- of the target material Bremsstrahlungis produced by e- interacting with the nucleus of a target tungsten atom
27. 27. Bremsstrahlung RadiationA projectile e- that completely avoids the orbital e- as it passes through a target atom may pass close enough to the nucleus of the atom to convert some of the projectile e- kinetic energy to EM energy Because of the electrostatic force?
28. 28. Bremsstrahlung Radiation
29. 29. Characteristic Radiation 2Steps Projectilee- with high enough energy to totally remove an inner-shell electron of the tungsten target Characteristicx-rays are produced when outer-shell e- fills an inner-shell void Alltube interactions result in a loss of kinetic energy from the projectile e-
30. 30. It is called characteristic because it is characteristic ofthe target element in the energy ofthe photon produced
31. 31. X-ray energy Characteristicx-rays have very specific energies. K-characteristic x- rays require a tube potential of a least 70 kVp Bremsstrahlung x-rays that are produced can have any energy level up to the set kVp value. Brems can be produced at any projectile e- value
32. 32. Discrete spectrum Contains only specific values
33. 33. Continuous Spectrum Contains all possible values
34. 34. Characteristic X-ray Spectrum Characteristic has discrete energies based on the e- binding energies of tungsten Characteristicx-ray photons can have 1 of 15 different energies and no others
35. 35. Characteristic X-RaySpectrum
36. 36. Bremsstrahlung X-raySpectrum Brems x-rays have a range of energies and form a continuous emission spectrum
37. 37. Factors Affectingthe x-ray emission spectrum Tubecurrent, Tube voltage, Added filtration, Target material, Voltage waveform Thegeneral shape of an emission spectrum is always the same, but the position along the energy axis can change
38. 38. Quality And Quantity ??
39. 39. mAs A change in mA or s or both results inthe amplitude change of the x-rayemission spectrum at all energies The shape of the curve will remain thesame
40. 40. mA increase from 200 to 400
41. 41. kVp A change in voltage peak affects boththe amplitude and the position of thex-ray emission spectrum
42. 42. Target Material The atomic number of the targetaffects both the quantity and quality ofx-rays Increasing the target atomic numberincreases the efficiency of x-rayproduction and the energy ofcharacteristic and bremsstrhlung x-rays
43. 43. Target material
44. 44. Voltage Waveform 5 voltage waveforms: half-waverectification, full-wave rectification, 3-phase/6-pulse, 3-phase/12-pulse, andhigh-frequency. Maintaining high voltage potential
45. 45. Voltage Generators
46. 46. X-Ray Interaction with Matter1. Photoelectric absorption2. Coherent scattering3. Compton scattering4. Pair production5. Photodisintegration
47. 47. Question ???