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X-RAY PRODUCTION BREMSTRAHLUNG RADIATION CHARACTERISTIC RADIATION.

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Presentation on theme: "X-RAY PRODUCTION BREMSTRAHLUNG RADIATION CHARACTERISTIC RADIATION."— Presentation transcript:

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 TARGET IS 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 CURRENT INTENSITY ENERGY – NO CHANGE 2 * mA = 2 * number of photons 4 * mA = 4 * number of photons

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

9 FILTRATION CHANGE FILTRATION INTENSITY ENERGY –

10 VOLTAGE WAVEFORM CHANGE VOLTAGE WAVEFORM INTENSITY ENERGY

11 PATIENT DOSE SINGLE PHASETHREE 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/kg 1 AIR KERMA=100R

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

17 rad= RADIATION ABSORBED DOSE 1 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 10 10 atomic disintegrations per secondThe unit is named for Pierre and Marie Curie, the discoverers of radium and polonium.


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