COMPREHENSIVE IMAGE
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| One way to alter image contrast and/or density digitally is through | windowing
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| The term windowing refers to | some change made to window width and/or window level
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| Change in window width affects change in | the number of gray shades, that is, image contrast
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| Change in window level affects change in | the image brightness, that is, optical density
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| Windowing and other postprocessing mechanisms permit the radiographer to affect changes in the image and to produce "special effects" such as | edge enhancement, image stitching (useful in scoliosis examinations), image inversion, rotation, and reversal
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| Using fixed-mAs and variable-kVp technical factors, each centimeter increase in patient thickness requires what adjustment in kilovoltage? | Increase 2 kVp
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| A film artifact usually will appear as a plus-density (dark) artifact if it is produced before or after exposure? | before
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| A film artifact usually will appear as a minus-density (light) artifact if it is produced before or after exposure? | after
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| Quantum mottle is a grainy appearance on a finished radiograph that is seen especially in fast-imaging systems or slow-imaging systems? | fast
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| What does quantum mottle look like? | it has a spotted or freckled appearance
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| Which would be more likely to cause quantum mottle, low mAs or high mAs? | low mAs
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| Which is more likely to cause quantum mottle, low kVp or high kVp? | high kVp
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| The sensitometric curve may be used to | 1. identify automatic processing problems.
2. determine film sensitivity.
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| The sensitometric, or characteristic, curve is used to illustrate the relationship between exposure and | the resulting film density
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| How does a sensitometric curve predict a film emulsion's response(speed, sensitivity)? | by determining how long it takes to record a particular density
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| The sensitometric curve is used in sensitometry to monitor | automatic processing efficiency and consistency
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| A film is given a series of predetermined exposures and processed, The resulting densities are plotted, and the resulting curve is compared with a known correct curve, a known correct curve | processing difficulties
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| The sensitrometric curve illustrates the effects of exposure and processing on | radiographic film emulsion
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| Size distortion is | magnification
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| Shape distortion is a result of improper alignment of | the x-ray tube, the part being radiographed, and the image recorder
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| the two types of shape distortion are | foreshortening and elongation
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| The shape of various structures can be radiographically misrepresented as a result of | their position in the body, when the part is out of the central axis of the x-ray beam, or when the central ray is angled
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| Which type of error results in grid cutoff at the periphery of the radiographic image? | Off-focus
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| If FOV increases, pixel size | increases
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| Geometric unsharpness is most likely to be greater | at the cathode end of the image
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| If 10% of the illuminator's light passes through the film, that film has a density of | 1
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| Which of the following can affect histogram appearance? | 1. Centering accuracy
2. Positioning accuracy
3. Processing algorithm accuracy
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| Angulation of the part with relation to the IR results in | foreshortening of the object
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| Tube angulation causes | elongation of the object
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| line focus principle | as the target angle decreases, the effective focal spot decreases (providing improved recorded detail), but the actual area of electron interaction remains much larger (allowing for greater heat capacity)
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| Does a steep (small) target angle increases or decrease the heel affect? | increase
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| The term field of view is used to describe | how much of the patient (eg, 150-mm diameter) is included in the matrix
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| The factors that affect the recorded detail of traditional screen/film imaging are | focal spot size, source-to-image distance (SID), object-to-image distance (OID), film/screen speed, and motion
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| Developing agents | change the exposed silver bromide crystals to black metallic silver, thus producing a manifest image
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| The fixer solution | removes the unexposed silver bromide crystals from the emulsion and hardens the gelatin emulsion, thus ensuring permanence of the radiograph
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| Which of the following functions to increase the mA? | Increasing the heat of the filament
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| A screen lag test is performed by radiographing a phantom using an empty cassette-image receptor, then loading it with film and leaving for it a few minutes. | If, after processing, there is any indication of an image, there is most probably screen lag.
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| Which of the following pathologic conditions require(s) a decrease in exposure factors? | 1. Pneumothorax
2. Emphysema
3. Multiple myeloma
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| Radiographic contrast is a result of | 1. differential tissue absorption.
2. emulsion characteristics.
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| Luminescence | the production of energy in the form of light
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| A film emulsion having wide latitude is likely to exhibit | low contrast
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| A gentle curve (as opposed to a steep curve) usually indicates a film with | slow speed, low contrast, and more latitude.
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| Grid ratio is defined as | the ratio between the height of the lead strips and the width of the distance between them (ie, their height divided by the distance between them).
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| anode angles of 10 degrees or less increase what? | anode heel effect
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| The iodine-based contrast material used in intravenous (IV) urography gives optimum opacification at what kVp? | 60 to 70kvp
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| how to find percentage difference between 2 numbers | X and Y is: Y/X - 1
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| The function(s) of automatic beam limitation devices include | reducing the production of scattered radiation
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| Grid frequency refers to | the number of lead strips per inch
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| Factors that contribute to an increase in the intensification factor generally function to increase or decrease resolution? | decrease
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| As intensification factor increases, does radiographic density generally increase or decrease? | increase
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| Which of the following factors contribute(s) to the efficient performance of a grid? | 1. Grid ratio
2. Number of lead strips per inch
3. Amount of scatter transmitted through the grid
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| The greater the number of lead strips per inch | the thinner and less visible they will be on the finished radiograph
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| The function of a grid is to | absorb scattered radiation in order to improve radiographic contrast
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| The selectivity of a grid is determined by | the amount of primary radiation transmitted through the grid divided by the amount of scattered radiation transmitted through the grid
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| Characteristics of digital radiographic imaging include | 1. solid state detector receptor plates.
2. direct-capture imaging system.
3. immediate image display.
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| The fact that x-ray intensity across the primary beam can vary as much as 45% describes the | anode heel effect
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| Over- or underexposure under the anode is usually the result of | exceeding the focusing distance limits in addition to being off-center
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| Which of the following units is used to express resolution? | 1. Line-spread function
2. Line pairs per millimeter
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| Which of the following will result if developer replenishment is inadequate? | Images with excessively low contrast
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| The formula used to determine magnification factor is: | MF = SID/SOD
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| The formula for magnification factor is | MF = image size/object size.
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| The atomic number of the tissues under investigation is directly related to their | attenuation coefficient
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| To produce a just perceptible increase in radiographic density, the radiographer must increase the mAs by | 30%
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| The violet light emited by the photostimulable phosphor (PSP) is transformed into the image seen on the CRT by the | ADC
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| The latent image appears as the PSP is scanned by | a narrow high-intensity helium-neon laser to obtain the pixel data
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| As the plate is scanned in the CR reader, it releases a violet light—a process referred to as | photo-stimulated luminescence
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| The luminescent light from the plate is converted to | electrical energy representing the analog image
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| The electrical energy is sent to an analog-to-digital converter (ADC) where it is | digitized and becomes the digital image that is eventually displayed (after a short delay) on a high-resolution monitor and/or printed out by a laser printer
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| Which of the following pathologic conditions are considered additive conditions with respect to selection of exposure factors? | 1. Osteoma
2. Bronchiectasis
3. Pneumonia
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| focal spot angle is usually | 12° to 17°
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| The steepness of the characteristic curve is representative of | image contrast
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| The steeper the curve, the greater the density differences and the higher the | contrast
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| The speed of the film is determined by | the curve's position on the log relative scale: When comparing two or more characteristic curves, the faster film lies
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| The faster the film speed, the less the | exposure latitude
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| In digital imaging, pixel size is determined by | dividing the FOV by the matrix.
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| Antihalation backing is | a component of single-emulsion film that prevents crossover of fluorescent light within an image receptor.
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| How efficiently the phosphors detect and interact with the x-ray photons is termed | quantum detection efficiency
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| How effectively the phosphors make this energy conversion is termed | conversion efficiency
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| The greater the percentage of scattered radiation absorbed compared to absorbed primary radiation, the greater the | "selectivity" of the grid
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| Recorded detail is improved using | a small focal-spot size, largest practical SID, shortest possible OID, and slowest practical screen/film combination and avoiding motion of the part being imaged.
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Created by:
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