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RadT 465
Image Acquisition and Evaluation
| Question | Answer |
|---|---|
| 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 |
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