Radiographic Exposure
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| Define contrast | difference in adjacent densities
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| Define quantity | The radiation intensity or the number of x rays in the beam, measured in mR
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| Define the relationship between ma and tube current | Directly proportional
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| Define the relationship between ma and mR | Directly proportional
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| Describe the relationship between exposure time and density | Directly proportional
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| Describe the relationship between time and mR | Directly proportional
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| Describe the relationship between mAs and density | Directly proportional
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| describe the relationship between kVp and mR | Inversely proportional
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| Describe the relationship between SID and mR | inversely proportional
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| Identify 4 imaging characteristics controlled by SID | magnification, distortion, penumbra and density
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| Define the reciprocity law. | Any combination of mA and time can be used to get the same mAs with the same result in density.
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| What is the 15% rule? | If kVp is increased by 15%, mAs will be halved. If kVp is decreased by 15%, mAs will be doubled.
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| ma + s = | mAs
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| What is the density maintenance formula? | new mAs/old mAs = new D^2/old D^2
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| What is meant by low contrast? | lots of gray
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| What is meant by high contrast? | few shades of gray
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| How do you get a higher contrast on a film? | lower the kVp
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| How do you get a lower contrast on a film? | Use a higher kVp
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| What are the prime factors for exposure? | mA, kVp, distance and time
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| What is quality? | the penetrability of the beam
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| What is the controlling factor of contrast? | kVp
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| What is the controlling factor of density? | mAs
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| What is the relationship between kVp and scatter? | Directly proportional
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| What is the function of contrast? | To make details visible
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| What is meant by short scale contrast? | Few shades of gray
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| What is meant by long scale of contrast? | Many shades of gray
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| What is subject contrast? | The range of differences in the intensity of the remnant x ray beam after it has been attenuated by the patient.
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| What is image receptor contrast? | The range of densities the image receptor is capable of recording.
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| Five factors that affect image receptor contrast | H & D curve, image density, processing, digital image receptors, intensifying screens
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| Three factors that affect subject contrast? | kVp, amount of tissue irradiated, type of tissue irradiated.
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| How does mAs affect radiographic contrast | Under or over exposure
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| How does focal spot size affect radiographic contrast | No influence.
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| How does the anode heel effect affect radiographic contrast? | Little effect
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| How does filtration affect contrast? | Inversely related.
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| How does beam restriction (collimation) affect contrast? | Inversely related.
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| How do grids affect contrast? | Directly related.
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| What are two types of motion? | Involuntary and voluntary.
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| Give an example of involuntary motion. | pain, breathing, chills, spasms
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| What is the typical range for O.D? | 0.25 to 2.5
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| How does SID affect density? | By a factor of 4 (inversely).
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| What are the seven types of radiologic tissue types. | metal, enamel, bone, muscle, fluids, fat and air/gas
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| Give an example of voluntary motion. | nervousness, discomfort, fear, excitability
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| Define density. | The overall blackness on the image. Also described as the amount of black metallic silver on a film.
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| What is fog? | Unwanted density on the film.
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| The total quantity of x rays produced in an x ray beam is determined by the _____. | mAs
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| The distance between the x ray tube and the film is? | Source to image distance (SID)
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| Low radiographic contrast is called? | long scale contrast
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| Two factors that directly control the amount of x rays emitted by the tube are? | ma and time
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| The shorter the SID, the __________ the intensity of the xray beam? | greater
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| Radiographic density if produced by? | The quantity of x rays reaching the image receptor.
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| Scattered radiation has what effect on radiographic contrast? | It decreases it.
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| Describe the relationship between filtration and density. | Inversely related.
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| descibe the relationship between collimation and density | inversely related
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| Describe the relationship between thickness and density. | Inversely related
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| Describe the relationship between grid ratio and density. | Inversely related.
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| Describe the relationship between thickness and contrast. | Inversely related.
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| Describe the relationship between processing time and contrast | Inversely related.
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