test 2 review Flashcards
in order to reduce patient exposure, what exposure factors should be considered?
high kVp, low mAs
As mAs increases, the quantity of radiation reaching the IR ________
increases
how much change in kVp will change the radiation exposure to the IR by a factor of 2
15%
where is the radiographic grid located?
between the patient and the IR
true/false: changes in kVp do not affect the exposure indicator number
false, they do not
true/false: the same mAs and kVp should be used on an AP lumbar spine and a lateral spine radiograph
false
a larger field size will result in _______________
increased scatter production
which of the following will limit the volume of tissue irradiated?
cone and collimator
what is electronic masking?
post processing collimation/”cropping” or “photoshopping”
the height of the lead strips relative to the distance between them is the measure of
grid ratio
which grid design is manufactured to match the divergence of the x-ray beam?
focused grid
once a predetermined amount of radiation reaches the AEC detector which of the following occurs
exposure is stopped
AEC determines _______; radiographer sets _____________
time; kVp and mA
when using AEC, what should the technologist use to adjust subject contrast on the image
kVp
a common cause for repeating images done with AEC is inaccurate
centering
accurate patient measurement is most critical with a __________________
variable kVp, fixed mAs chart
true/false: AEC can be used with tabletop exams
false
true/false: technique charts are not needed if using AEC
false
what is the relationship between mA and seconds to maintain exposure to the IR?
inverse proportional
as focal spot increases, unsharpness _____________ and spatial resolution ____________; you want a ____ focal spot
increases, decreases, small
increasing mAs has a _________ effect on the brightness on digital imaging
no
increasing OID ______________ magnification and _________________ spatial resolution
increases, decreases
which of the following factors does not affect spatial resolution?
focal spot size
SID
OID
grid
grid
with exposure technique compensation, which of the following would result in a the greatest radiation exposure to the patient?
14x17 field size
air gap technique
cylinder beam restrictor
12:1 grid ratio
12:1 grid ratio
off focus grid cutoff occurs by using an SID that is not _____________
within the focal range of the grid
the type of motion most often used for moving grids today is _____________
reciprocating
what is true for positive beam-limiting devices
they were once required on new radiographic installations
when making a significant increase in collimation, ______________________
mAs should be increased
according to Fauber text
AEC devices work by measuring ___________
radiation that exits the patient
how many detectors are typically found in an AEC system
three
minimum response time refers to ___________________
the shortest exposure time possible when an AEC device is used
in AEC, adjusting the ____________ __________________ affects the exposure to the IR
exposure adjustment control
what detector should be selected for a right AP shoulder when the patient is supine on the x-ray table?
center detector only
when using AEC with digital imaging systems, assuming all other factors are correct, selecting the center detector on a PA chest image results in ___________
increases exposure in the lung area
the ionization chamber interacts with ________________before it _____________
exit radiation, reaches the IR
in a variable kVp/fixed mAs chart, ___ kVp change for every 1 cm change in part thickness
2 kVp
in a fixed kVp/variable mAs chart, for every 4-5 cm, the mAs should be adjusted __________
by a factor of 2
