VTNE - Diagnostic Imaging Flashcards
The milliampere-seconds (mAs) setting on an x-ray machine controls the:
a. quality of the beam
b. quantity of x-rays emitted
c. speed of electrons emitted
d. wavelength of the beam
B. Quantity of x-rays emitted
exp: milliampere seconds, or mAs, determines the amount of the electrical energy applied to the filament per second and determines the number of x-rays produced during the exposure.
During an exposure, electrons in the x-ray tube travel from the:
a. anode to the cathode
b. anode to the target
c. cathode to the anode
d. cathode to the filament
C. Cathode to the anode
exp: the cathode provides the source of the electrons at the filament, and the kilovoltage directs the electrons to the anode during the exposure.
The acceleration of the electrons and their ultimate striking energy is determined by the
a. milliamperage (mA)
b. kilovoltage (kVp)
c. milliamperage-seconds (mAs)
d. exposure time (Time)
B. Kilovoltage
exp: the kilovoltage peak (kVp) determines the maximum speed of the electrons flowing across the x-ray tube. This determines the maximum energy of the x-ray photons produced and thus their penetrating power.
Regarding the production of x-rays in the x-ray tube, the:
a. purpose of the anode is to provide a source of electrons
b. target and focal spot are provided by the cathode
c. cathode side of the tube is positively charged, and the anode is negatively charged
d. cathode includes the filament and the focusing cup
D. Cathode includes the filament and the focusing cup
exp: The x-ray tube provides the source of the electrons, a method of accelerating them, a target for the interaction of the electrons to change into x-ray photons and heat, a method of heat dissipation, and a glass envelope to maintain the evacuated path for the accelerated electrons to travel. The negatively charged cathode provides the source of electrons through the heated filament, the focusing cup helps direct the path, and the kVp provides the method of acceleration. The anode provides the target and focal spot.
The heel effect is going to be more noticeable with:
a. larger film, longer focal-film distance, and higher kVp
b. larger film, shorter focal-film distance, and lower kVp
c. smaller film, shorter focal-film distance, and higher kVp
d. smaller film, longer focal-film distance, and lower kVp
B. larger film, shorter focal-film distance, and lower kVp
exp: because of the angle of the anode, there is a greater intensity of the x-ray beam toward the cathode side. As with beams of light, there is increasing spread of the beam from the source. The divergent effects are more noticeable with larger film, because a greater percentage of the beam is affected. The full effect of the beam, and the variation in intensity, are more noticeable with shorter focal-film distance. At lower kVp there is a greater variation in the intensity of the beam as compared to higher kVp, which leads to a more noticeable heel effect.
If using both blue- and green-sensitive films, what type of safelight should you use?
a. amber
b. blue
c. green
d. red
D. Red
exp: A red safelight has a light emission toward the red end of the spectrum (greater than 600nm) and does not expose either blue- sensitive or green-sensitive film. An amber safelight emits at about 500nm and does not expose blue-sensitive film but exposes green-sensitive film.
A safelight illumination test was performed in the darkroom. On processing the film, you see various gradations of blackness on your film. The area exposed for the longest period of time is:
a. green
b. clear
c. slightly gray
d. darkest
D. darkest
exp: A safelight illumination test often consists of covering various parts of an unexposed film for various time periods and exposing them to the safelight. The film is then processed. The length of time that the radiograph is exposed to safelight should be less than the time that you note any grayness on the blank film, otherwise your radiograph will show evidence of fogging. Because the developers main purpose is to convert the exposed silver halide crystals to black, the more exposed the crystals, the darker the image.
After you manually process a film, you notice that there is a green area of about 1/2 inch along one narrow edge of the film. This is due to the area not being:
a. developed
b. fixed
c. developed or fixed
d. exposed to radiation
C. developed or fixed
exp: The green is the original color of blue-sensitive film, which indicates that neither of the solutions has touched the film at this point.
You notice that there is a clear line at the top of the shorter edge of a radiograph that you have manually processed. This is due to the are not being:
a. developed
b. fixed
c. developed or fixed
d. collimated
A. developed
exp: If a radiographs not placed into the developer, any crystals that are exposed will not be turned to black. The fixer will clear away the undeveloped crystals, leaving no image in that area. Collimation, choice D, is more likely to be evidenced on all sides, and, because of scatter radiation, leaving an image that does not usually show up as totally clear.
You are looking at a film that is totally clear except for a bit of black that you notice along the edges. Your film has not been
a. developed
b. fixed
c. developed or fixed
d. exposed to radiaiton
D. Exposed to radiation
exp: The black area along the edges likely indicates a light leak, which demonstrates that the film must have been processed correctly. The film has not been exposed to any radiation, because there are no exposed silver halide crystals to be converted to black.
The remaining silver halide crystals from exposed x-ray film are removed in the
a. fixer
b. developer
c. wash water
d. storage envelope
A. Fixer
exp: the fixer removes the silver halide crystals into soluble compounds and dissolves them away. Silver can be recovered from the fixer.
Which of the following would cause the image on a processed x-ray film to be fogged?
a. two films in the same cassette
b. kVp too low
c. film stored in an area of high room temperature
d. focal-film distance too long
C. film stored in an area of high room temperature
exp: high room temperature degrades the quality of the film, so that the film contrast is minimized. There are fewer white or transparent areas. A low kVp, a long source-image distance, and two films in the cassette would cause a lighter image.
