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40 terms

Ch. 11

STUDY
PLAY
secondary radiation
radiation produced by the photoelectric effect is called
fog, reduced contrast, reduced recorded detail
scattered radiation affects the radiographic image by causing
kVp, field size
which of the following factors will affect the quantity of scattered radiation fog on a radiograph
use a grid or Bucky
the most effective method of reducing scattered radiation fog on a radiograph is to
the relationship between the height of the lead strips and the width of the spaces between them
the effectiveness of a grid is determined by the grid ratio, which is
clean up scattered radiation more effectively
as compared with an 8:1 ratio grid, a 12:1 ratio grid will
grid cutoff
on a radiograph, the appearance of decreased density on the side of the image is most likely caused by
bucky grid
a moving grid may be part of a radiographic table or upright unit and is called a
visibility of grid lines
the frequency of a stationary grid affects the
10 to 12 cm
as general rule, a grid or Bucky should be used when the part thickness is greater than
lateral angulation, SID out of the focal range, position of the x-ray beam off center to one side of the grid
which of the following would result in grid cutoff
using an air gap, using a smaller field size
which of the following will reduce scatter radiation
compton effect
in the diagnostic range of kvp settings (50 to 100 kVp) the majority of scattered radiation will be from which interaction with matter
the photoelectric effect
total absorption of an x-ray photon by the atom of the body part it is termed
back toward the x-ray tube
the majority of photons that are scattered will scatter in which direction
+/- 2% of the SID
the standard control limit for the collimator on the x-ray tube is that it must be maintained within a range of
true
higher kVp results in more scattered radiation fog
true
the effectiveness of a grid is determined by grid ratio
false
high-frequency or stationary grids move during the exposure
false
a grid with strips that are parallel to each other is called a crosshatch grid
false
an air gap with increased OID increases the intensity of scattered radiation at the image receptor (IR)
false
a grid ratio of 12:1 would be used for mobile radiography
true
the number of lead strips per inch is called the grid frequency
true
increase tissue thickness equals increased interactions equals increased scatter equals increased fog
true
the patient is the prinicipal source of scattered radiation in radiography
true
a grid is placed between the patient and the IR
false
compton scatter travels in a forward direction only
true
scatter radiation fog reduces the visibility of detail
true
the standard control limit for the x-ray tube's beam alignment is that the tube must be mounted so that the beam is within 1 degree of perpendicular
false
the collimator and the beam alignment must be checked using two separate quality control tests
photoelectric effect interactions
which type of radiation interaction produces scattered radiation that is characteristic of the subject irradiated
thickness of subject, size of field
what two factors affect the volume of the tissue irradiated
increased, high energy able to escape subject without being reabsorbed
when the kvp is increased, will the quantity of secondary radiation fog be increased or decreased, why
patient
what is the principal source of scattered radiation that causes fog in radiography
12:1
state the grid ratio that is typical of a table bucky
103 lines per inch with ration of 8:1 or 12:1
what is the usual minimum frequency for a stationary grid in an upright grid cabinet
visible grid lines
what is the typical radiographic appearance of grid cutoff caused by using an SID that is outside the grid's focal range
lateral projection of the cervical spine
for what radiographic examination is an air gap commonly used instead of a grid
increased image quality because of decrease in distortion
how might the image of a vertebra on a spot film differ from the image of the same vertebra as part of a 35 x 43 cm radiograph of the spine
if part measures 10 to 12 cm or greater refer to technique chart
how would you determine when to use a grid