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X-RAY PRODUCTION

X-RAY PRODUCTION. BREMSTRAHLUNG RADIATION CHARACTERISTIC RADIATION. MAXIMUM ENERGY OF AN X-RAY IN THE BEAM. kVp OF OPERATION kV peak. ONE PHOTON ENERGY. keV kilo-electron-volt. GREATEST # OF PHOTONS IS EMITTED WITH ENERGY:. APPROX. 1/3 OF MAX PHOTON ENERGY.

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X-RAY PRODUCTION

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  1. X-RAY PRODUCTION • BREMSTRAHLUNG RADIATION • CHARACTERISTIC RADIATION

  2. MAXIMUM ENERGY OF AN X-RAY IN THE BEAM kVp OF OPERATION kVpeak

  3. ONE PHOTON ENERGY keV kilo-electron-volt

  4. GREATEST # OF PHOTONS IS EMITTED WITH ENERGY: APPROX. 1/3 OF MAX PHOTON ENERGY

  5. FOUR PRINCIPAL FACTORS INFLUENCING THE SHAPE OF AN X-RAY EMISSION SPECTRUM: • ELCTRONS TRAVELING FROM CATHODE TO ANODE HAVE DIFFERENT ENERGIES– NOT JUST PEAK ENERGY • THE TARGETIS RELATIVELY THICK– CAUSING MULTIPLE INTERACTIONS. • LOW ENERGY X-RAYS ARE MORE LIKELY ABSORBED IN THE TARGET • EXTERNAL FILTRATION REMOVES LOW ENERGY PHOTONS

  6. FACTORS AFFECTING THE X-RAY EMISSION SPECTRUM • TUBE CURRENT • TUBE VOLTAGE • ADDED FILTRATION • TARGET MATERIAL • VOLTAGE WAVEFORM

  7. CURRENT CHANGE INTENSITY ENERGY – NO CHANGE CURRENT 2 * mA = 2 * number of photons 4 * mA = 4 * number of photons

  8. Tube voltage (kVp) CHANGE INTENSITY ENERGY – kVp 15% INCREASE OF KVP = 2 * mAs

  9. FILTRATION CHANGE INTENSITY ENERGY – FILTRATION

  10. VOLTAGE WAVEFORM CHANGE INTENSITY ENERGY VOLTAGE WAVEFORM

  11. PATIENT DOSE SINGLE PHASE > THREE PHASE

  12. RADIOLOGIC QUANTITIES SI UNITS • EXPOSURE ---AIR KERMA (Gya) • ABSORBED DOSE---GRAY (Gyt) • EFFECTIVE DOSE---SEIVERT (Sv) • RADIOACTIVITY---BECQUEREL (Bq)

  13. RADIOLOGIC QUANTITIES CUSTOMARY UNITS • EXPOSURE ---ROENTGEN (R) • ABSORBED DOSE---rad (rad) • EFFECTIVE DOSE---rem (rem) • RADIOACTIVITY---curie

  14. EXPOSURE ( INTENSITY) THE TOTAL ELECTRICAL CHARGE PER UNIT MASS THAT X-RAY AND GAMMA RAY PHOTONS GENERATE IN DRY AIR.

  15. 1R=2.58 x 10-4 C/kg1 AIR KERMA=100R

  16. ABSORBED DOSE THE AMOUNT OF ENERGY PER UNIT MASS ABSORBED BY THE IRRADIATED OBJECT

  17. rad= RADIATION ABSORBED DOSE1 GRAY=100 rad

  18. EFFECTIVE DOSE PROVIDES A MEASURE OF THE OVERALL RISK OF EXPOSURE TO IONIZING RADIATION. UNIT OF OCCUPATIONAL EXPOSURE DOSE. 1 Sv = 100 rem

  19. The SI derived unit of activity, usually meaning radioactivity. "Radioactivity" is caused when atoms disintegrate, ejecting energetic particles

  20. RADIOACTIVITY • The SI derived unit of activity, usually meaning radioactivity. "Radioactivity" is caused when atoms disintegrate, ejecting energetic particles. One becquerel is the radiation caused by one disintegration per secondThe unit is named for a French physicist, Antoine-Henri Becquerel (1852-1908), the discoverer of radioactivity • One curie was originally defined as the radioactivity of one gram of pure radium. In 1953 scientists agreed that the curie would represent exactly 3.7 x 1010 atomic disintegrations per secondThe unit is named for Pierre and Marie Curie, the discoverers of radium and polonium.

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