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RadT 465

Image Acquisition and Evaluation

QuestionAnswer
What factors affect recorded detail/resolution? (Lange Prep, p. 298) OID, SID, focal spot, patient factors, intensifying screens, motion
Image quality consists of what factors? (Lange Prep, p. 298) Density, contrast/gray scale, recorded detail and distortion
What are the exposure factors used? (Lange Prep, p. 298) mA, time kV, distance
What are some patient variables? (Lange Prep, p. 298) Tissue density, tissue thickness, pathology, and ability to cooperate
The clarity, or resolution, with witch anatomic structures are represented in the x-ray image. (Lange Prep, p. 298) Recorded detail
Misrepresentation of the actual size or shape of the structures imaged. (Lange Prep, p. 299) Magnification
An increase in OID increases what? (Lange Prep, p. 301) Magnification
Geometrically recorded detail improves as what decreases? (Lange Prep, p. 301) OID
Geometrically recorded detail improves as what increases? (Lange Prep, p. 301) SID
A linear structure angled within the body, that is, not parallel with the long axis of the part/body and not parallel to the IR, that anatomic structure will appear smaller. It will appear? (Lange Prep, p. 303) Foreshortened
What occurs when the x-ray tube is angled? (Lange Prep, p. 303) Elongation
The finite area on the tungsten target that is actually bombarded by electrons from the filament. (Lange Prep, p. 305) Actual focal spot
The foreshortened size of the of the focus as it is projected down toward the IR. (Lange Prep, p. 305) Effective focal spot
Unsharpness is ___________ related to focal spot size and OID, and _______ related to SID. (Lange Prep, p. 308) Directly; inversely
What is the best method for minimizing voluntary motion? (Lange Prep, p. 309) Good communication and suspended respiration
What is the best method for minimizing involuntary motion? (Lange Prep, p. 309) Shortest exposure time
What are rare earth phosphors? (Lange Prep, p. 311) Gadolinium, lanthanum, yttrium
What percent of the exposure received by the film emulsion is from fluorescent light? (Lange Prep, p. 311) 98%
Intensifying screen speed increases as what factors increase? (Lange Prep, p. 312) Phosphor size, active/phosphor layer thickness, phosphor sensitivity, screen reflectance, recorded detail decreases
Recorded detail/spatial resolution increases as what factors are altered? (Lange Prep, p. 312) Focal spot size decreases, SID increases, OID (magnification) decreases, motion decreases, (shape) distortion decreases, screen speed decreases
The color of light emitted must match the sensitivity of the film emulsion used is known as? (Lange Prep, p. 312) Spectral matching
The luminescence from fluoroscopic screen phosphors is? (Lange Prep, p. 312) Phosphorescence
Screen speed is directly related to? (Lange Prep, p. 312) Phosphor size, phosphor layer thickness, and degree of reflective backing
As intensifying screen speed _______, patient dose ________, and x-ray tube life ________. (Lange Prep, p. 313) Increases, decreases, increases
The overall amount of blackening on a radiographic image or particular portion of the image. (Lange Prep, p. 314) Radiographic/image density
The amount of image blackening determined by the number of x-ray photons used to create the image? (Lange Prep, p. 315) Quantitative factor
The product of millamperes and exposure time. (Lange Prep, p. 316) Milliampere-seconds
Any combination of mA and exposure time that will produce a particular mAs, will produce identical image density. (Lange Prep, p. 317) Reciprocity law
Directly proportional to the intensity/exposure rate/number of x-ray photons produced. (Lange Prep, p. 317) mAs
The intensity of light at a particular distance from its sources is inversely proportional the the square of the distance. (Lange Prep, p. 318) Inverse square law
As distance in decreased, the intensity of the x-ray beam increases. (Lange Prep, p. 320) Density maintenance formula
When manipulation of mAs is not possible, the density can be doubled or cut in half by using the? (Lange Prep, p. 321) 15% rule
Screen speed and image density are directly/inversely proportional? (Lange Prep, p. 322) Directly
Screen speed and patient dose are directly/inversely proportional? (Lange Prep, p. 322) Inversely
Screen speed and image resolution/sharpness are directly/inversely related? (Lange Prep, p. 322) Inversely
What adds unwanted and degrading densities to the x-ray image? (Lange Prep, p. 322) Scatter radiation
A grid is recommended for body parts measuring greater than? (Lange Prep, p. 323) 10 cm or 4 inches
When imaging large body parts without a grid, scatter radiation contributes what percentage of the total exposure? (Lange Prep, p. 323) 50%
What are the types of grids? (Lange Prep, p. 324) Parallel or focused and stationary or moving
What type of grid is used in mobile radiography? (Lange Prep, p. 324) Stationary grid
What are some errors when using a focused grid? (Lange Prep, p. 324) Angulation errors, off-level errors, off-focus errors, off-center errors, and upside-down grid placement
The height of the lead strips compared with the distance between them (Lange Prep, p. 326) Grid ratio
The number of lead strips per inch is known as? (Lange Prep, p. 326) Grid frequency
The amount by which mAs must be changed to compensate for the radiation absorbed by the grid is? (Lange Prep, p. 327) Grid conversion factor
The ratio of radiographic contrast obtained with a grid compared to contrast obtained without a grid. (Lange Prep, p. 327) Contrast improvement factor
The ratio between the quantity of useful photons transmitted through the grid and the quantity of scattered photons transmitted. (Lange Prep, p. 327) Selectivity
What does filtration do? (Lange Prep, p. 330) Reduces patient skin dose, minimum 2.5 mm Al equivalent, increases overall average energy of the x-ray beam
Why are compensating filters used? (Lange Prep, p. 330) For atomic parts having very different thickness/absorption properties and used to balance tissue densities, improves visualization of all tissues
What are additive pathologic conditions? (Lange Prep, p. 333) Ascites, rheumatoid arthritis, paget disease, pneumonia, atelectasis, congestive heart failure, edematous tissue
What are negative/degenerative pathologic conditions? (Lange Prep, p. 333) Osteoporosis, osteomalacia, pneumoperitoneum, emphysema, degenerative arthritis, atrophic and necrotic conditions
What is used to compensate for a difference in tissue density/thickness? (Lange Prep, p. 339) Anode heel effect
The greater x-ray intensity is at the ________ end when using the anode heel effect. (Lange Prep, p. 339) Cathode
Optical density increases as developer temperature ______ and as the replenishment rate and/or length of development ______. (Lange Prep, p. 339) Increases, increase
The purpose of contrast is to? (Lange Prep, p. 339) Make details visible
Radiographic contrast is the sum of what two factors? (Lange Prep, p. 339) Subject contrast and film contrast
Subject contrast is regulated by the quality/quantity of x-ray photons? (Lange Prep, p. 339) Quality
High contrast is? (Lange Prep, p. 340) Short-scale, few, very different image/tissue densities, and is the product of lower kV, few dissimilar tissue densities, and tighter collimation
Low contrast is? (Lange Prep, p. 340) Long-scale, displays many similar image/tissue densities, and is the product of higher kV, many similar tissue densities and larger field sizes
The result of manufacturing, processing, and intensifying screens. (Lange Prep, p. 341) Film contrast
The leeway or margin of error one has with a given group of exposure factors. (Lange Prep, p. 342) Exposure latitude
As grid ratio increases, what happens? (Lange Prep, p. 347) Scattered radiation cleanup increases, contrast improves, contrast scale decreases, exposure factors increase, patient dose increases positioning latitude decreases
The primary beam has a total filtration of? (Lange Prep, p. 347) 2.5mm Al
What are the two types of ionization chambers? (Lange Prep, p. 349) Phototimer and ionization chamber
Where is the ionization chamber located? (Lange Prep, p. 351) Between the x-ray table and cassette
Where is the phototimer located? (Lange Prep, p. 351) Beneath the IR
What is the shortest exposure time possible with a particular AEC? (Lange Prep, p. 351) Minimum reaction time
What are the limitations of screen/film processing? (Lange Prep, p. 352) Narrow exposure latitude, chemical processing, increased cost, storage space requirements, no image enhancement capabilities, no electronic transmission capability
What are the advantages of screen/film processing? (Lange Prep, p. 353) High spatial resolution, image consistency
A pixel is? (Lange Prep, p. 355) Two dimensional, picture element, measured in XY direction
What is the distance between pixels and impacts spatial resolution? (Lange Prep, p. 355) Pixel pitch
What is a voxel? (Lange Prep, p. 355) The third dimension, depth, volume element, measured in the z direction
What is a matrix? (Lange Prep, p. 355) Number of pixels in the XY direction
What is the field of view? (Lange Prep, p. 355) How much of the part/patient is included in the matrix.
Pixel size is affected by? (Lange Prep, p. 356) Change in matrix size, and change in field of view
CR spatial resolution improves with what factors? (Lange Prep, p. 356) Smaller pixel pitch, greater pixels/mm, and greater sampling frequency
As the signal to noise ratio increases, contrast resolution? (Lange Prep, p. 356) Improves
When using a PSP system, the image receptor is made of a layer of? (Lange Prep, p. 358) Europium activated barium fluorohalide
The barium fluorohalide phosphors are? (Lange Prep, p. 358) Granular or tubid
PSP plates are sensitive to what? (Lange Prep, p. 360) X-rays, ultraviolet, gamma, and particulate radiation
Inconsistent scanning motion that results in a wavy or otherwise distorted image. (Lange Prep, p. 361) Laser jitter
What is the percentage for dynamic range and exposure latitude overexposure and underexposure? (Lange Prep, p. 361) Overexposure: 500% Underexposure: 80%
Indirect-capture flat panel detector is made of? (Lange Prep, p. 363) Cesium iodide or gadolinium oxysulfide as the scintillator
In indirect-capture, the scintillator captures x-ray photons and? (Lange Prep, p. 363) Emits light
A TFT flat panel detector is composed of glass with what on both sides? (Lange Prep, p. 364) Amorphous selenium
In direct flat panel detector systems, x-ray energy is converted to an ______ ______. (Lange Prep, p. 364) Electric signal
Direct flat panel detector systems eliminate what step that indirect systems use? (Lange Prep, p. 364) The scintillator step
What are features of the PACS system? (Lange Prep, p. 366) Image acquisition, image display and interpretation, image archival and retrieval, image communication
The most common result of improper film storage? (Lange Prep, p. 381) Fog
Unexposed film should be stored at what temperature? (Lange Prep, p. 381) No greater than 70 degrees F
The humidity should not exceed what percentages to prevent damage in the form of static electricity or fog? (Lange Prep, p. 381) Between 40% and 60%
Film boxes should be stored in what position? (Lange Prep, p. 381) Upright
What are types of film artifact? (Lange Prep, p. 383) Handling, processing, exposure
What information is required on an x-ray film? (Lange Prep, p. 384) Patient name/identification number, side marker, examination date, institution name
What information is optional on an x-ray film? (Lange Prep, p. 384) Patient age or date of birth, attending physician, time of day, radiographer identification
The film emulsion is made of? (Lange Prep, p. 385) Silver bromide grains/crystals
What forms the inner portion of emulsion? (Lange Prep, p. 385) Positive silver ions
What forms the outer layer of emulsion? (Lange Prep, p. 385) Negative silver ions
What does developer do? (Lange Prep, p. 385) Coverts the latent image to the manifest image
What factors affect the development process? (Lange Prep, p. 385) Temperature, time, and solution activity
What is added to the developer to prevent rapid oxidation? (Lange Prep, p. 385) Preservative
What is added to the developer to restrict it activity to only the exposed silver grains? (Lange Prep, p. 386) Restrainer/antifog
The function is to shrink and reharden the softened gelatin emulsion? (Lange Prep, p. 386) Fixer
What rids the film of the residual chemicals? (Lange Prep, p. 386) Wash
Removes water from the film and shrinks and dries the emulsion? (Lange Prep, p. 386) Dryer
Reduces exposed silver bromide to black metallic silver. (Lange Prep, p. 386) Developer
Clears the film of the unexposed silver bromide and rehardens the emulsion? (Lange Prep, p. 386) Fixer
conveys the film through the different processor sections by means of a series of rollers? (Lange Prep, p. 386) Transport system
Changes the direction of the film as it goes from a down direction to an upward direction? (Lange Prep, p. 387) Turnaround assemblies
Deflector plates located where the film changes direction? (Lange Prep, p. 387) Guide shoes
Keeps the solution tanks full. (Lange Prep, p. 387) Replenishment system
Developer temperature is maintained at what degree F? (Lange Prep, p. 387) 92-95 degrees F
Provides agitation necessary for uniform solution concentration? (Lange Prep, p. 388) Recirculation system
Functions to keep fresh solution in contact with the film emulsion? (Lange Prep, p. 388) Agitation
Dryer temperature is kept between what degrees? (Lange Prep, p. 388) 120 -130 degrees F
What is the film processor system? (Lange Prep, p. 388) Transport system, replenishment system, temperature regulation system, recirculation system, washer system, dryer system
What are methods of silver recovery? (Lange Prep, p. 388) Electrolytic, metallic displacement
A PSP system can store an image up to how many hours before fading begins? (Lange Prep, p. 391) 8 hours
The direction of the lead strips and the gridlines per inch match the scan frequency of the scanner/reader film produces what artifact? (Lange Prep, p. 392) Moire effect or aliasing
The PSP plate should be erased before use after sitting for how many hours without use? (Lange Prep, p. 394) 48 hours
A graphic representation of pixel value distribution. (Lange Prep, p. 394) Histogram
A characteristic curve that best matches the anatomic part being imaged, to provide the appropriate gray-scale rendition. (Lange Prep, p. 394) Look up table
Changes in ______ affect change in the number of gray shades. (Lange Prep, p. 396) Window width
Change in ______ affect change in the image brightness. (Lange Prep, p. 396) Window level
Causes of CR graininess are? (Lange Prep, p. 405) Underexposure, incorrect processing/processing algorithm/ LUT, excess scatter radiation, inadequate collimation, grid misalignment;cutoff
CR resolution increases as what factors are altered? (Lange Prep, p. 406) PSP phosphor size decreases, laser beam size decreases, monitor matrix size increases
Shielding should be seen when the primary beam is _____ cm from the gonad area. (Lange Prep, p. 408) 5 cm
Exposure artifacts include? (Lange Prep, p. 419) Hair pins, dentures, necklaces/jewelry
Handling artifacts are? (Lange Prep, p. 419) Scratches, dust, crescent marks, static discharge
Processing artifacts include? (Lange Prep, p. 419) Chemical processing of the film or from processing of digital images
What cleaning solution is recommended for PSP systems? (Lange Prep, p. 423) Anhydrous ethanol
Created by: KelliAnn2292