Components of - El Camino College组件-埃尔卡米诺学院.docVIP

Components of Image Quality  Radiographic Artifacts Radiologic Technology A Spring 2010 X-ray Exposure Factors Radiographic Density Contrast Components of Image Quality Radiographic Artifacts Review Chapter 7 Primary radiation exits the tube Interacts with various densities in the body Photons may be absorbed Scattered Passed through without any interference to the cassette or image receptor (IR) How well we can see something on the image Image detail is affected by:Photographic propertiesand Geometric properties Photographic Properties __________ __________ X-ray Exposure Factors TECHNIQUE SELECTION: Radiographer selects the Kilovoltage peak (kVp) Milliamperage (mA) time (s) Milliamperage x time = mAs (milliamperage multiplied by a set time measured in seconds) Kilovoltage Peak kVp One kilovolt = 1000 volts The amount of ________ selected for the x-ray tube. Range 30 to 150 kVp kVp controls __________ ? Milliamperage One milliampere (mA) = one thousandth of an ampere. The amount of ____________ supplied to the x-ray tube How ______________ x-rays will be produced Range 10 to 1200 mA Time In seconds How long x-rays will be produced 0.001 to 6 seconds Milliampere Seconds Technologists think in terms of mAs Calculated by mA x seconds Ex: 100mA X 0.2s = 20 mAs How many x-rays will be produced and for how long. Modern x-ray machines only allow control of mAs controls _______________ ? Factors Affecting Density Primary control factor mA Time (seconds) Influencing factors kVp Grids Beam restriction Body structures (size of pt, pathology Processing SID OID Film Screen combinations Primary Controlling Factor of Density mAs mA = ___________ of electrons sent across the tube combined with TIME (S) = mAs mAs controls ________ on radiograph primary function of mAs is DENSITY Imagine this… If the mA station is changed from 200 to 400 mA, twice as many electrons will flow from the cathode to the anode. From 10 mA to 1000 mA = 100 x more mA controls h