GREATEST # OF PHOTONS IS EMITTED WITH ENERGY: APPROX. 1/3 OF MAX PHOTON ENERGY
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
FACTORS AFFECTING THE X-RAY EMISSION SPECTRUM TUBE CURRENT TUBE VOLTAGE ADDED FILTRATION TARGET MATERIAL VOLTAGE WAVEFORM
CURRENT CHANGE CURRENT INTENSITY ENERGY – NO CHANGE 2 * mA = 2 * number of photons 4 * mA = 4 * number of photons
Tube voltage (kVp) CHANGE kVp INTENSITY ENERGY – 15% INCREASE OF KVP = 2 * mAs
EFFECTIVE DOSE PROVIDES A MEASURE OF THE OVERALL RISK OF EXPOSURE TO IONIZING RADIATION. UNIT OF OCCUPATIONAL EXPOSURE DOSE. 1 Sv = 100 rem
The SI derived unit of activity, usually meaning radioactivity. "Radioactivity" is caused when atoms disintegrate, ejecting energetic particles
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.