RTE 1418 Exam Review Flashcards
which kVp selection (high or low) will result in more scattered XRs in the img-forming beam?
high
Decreasing kVp will increase?
pt dose, img noise, Compton scatter, OD
pt dose
3 things that improve contrast resolution
tight coll, lowering kVp, pt compression
the use of a compression device will increase?
contrast
the use of ______ improves contrast and reduces pt dose
collimation
how can you improve img contrast w a heavy pt w/o increasing pt dose?
use tight collimation
img contrast improves when more of ______ rad is removed
scattered
a grid is constructed w _______ strips and ______ interspace material
radiopaque, radiolucent
an XR w a long scale contrast will also have _____ latitude and _____ contrast
wide, low
grids are designed to remove scattered XRs before they reach?
the IR
what is the grid ratio of a grid w 3-mm height, 0.025-mm thick lead grid strips, and 0.3-mm thick interspace material?
10:1
foreshortening is caused by a(n)
angled body part when the beam is perpendicular to the IR
OD is directly controlled by changing the _____
mAs
pt thickness affects img quality by affecting what 3 things?
magnification, rad contrast, & focal spot blur
the best way to min. magnification is to use a
long SID and small OID
subject contrast is affected by
pt thickness
3 primary factors influencing the intensity of scatter in the img-forming beam are
kVp, field size, & pt thickness
scatter rad increases as ______ increases
field size
the most commonly used beam restricting device is the
variable collimator
the positive beam limiting device (PBL) ensures that the XR beam is collimated to
the IR size
_______ is the degree of difference in the OD btw areas of an img
contrast
what does the angle of the scattered photon, the height of the grid strips, and the width of the interspace material have in common?
the amount of scatter absorption in a grid depends on these factors
what is the formula for grid ratio?
h/D
the purpose of a grid is to achieve?
improved img contrast
the interspace material in grids are made of?
aluminum and/or plastic fiber
grids generally have a frequency of ______ lines per inch
60-110
grids generally have a frequency of ______ lines per cm
25-45
the most critical consideration when using a crossed grid is
alignment (positioning latitude)
how could contrast be improved on a bedside XR of a very large pt?
use grid, use tight coll., lower kVp
which is the linear grid w the widest latitude for centering and focus?
(6:1, 10:1, 12:1. 16:1)
6:1
spatial resolution improves with decreased? (3)
screen blur, motion blur, and geometric blur
radiographic _______ is random fluctuation in the OD of an XR
noise
the slope of the _______ portion of the char. curve shows the film contrast
straight line
if 10% of the view box light is transmitted through an area of film, what is the OD in that area?
1
a film w a char. curve showing a high slope would be useful when ________ is needed
high contrast
the 3 primary geometric factors affecting img qual are?
magnification, distortion, & focal spot blur
distortion can be reduced by?
placing the object plane II to IR
focal spot blur can be reduced using a
small focal spot
XR img qual. is improved when the ________ is increased
SID
High speed IRs generally produce XRs w?
increases noise
the ability to img 2 separate objects and visually detect one from the other
resolution
an IR w __________ can be used over a greater range of exposures
wide latitude
formula for OD?
OD=log base 10(original intensity/transmitted intensity),
OD=log10(Io/It)
the densities above 2.5 on a film are represented in the _____ portion of the char. curve
shoulder
sharpness of detail can be improved by increasing ______
SID
(Char. curve) film w highest contrast
steeper slope
(Char. curve) film w highest speed
curve closest to y-axis
(Char. curve) film w widest latitude
wider slope
(Char. curve) film w short-scale contrast
steeper slope
lowering kVp _______ pt dose and _______ img contrast
increases, increases
modern rad film base is made of?
polyester
how thick is rad film base?
150-300 µm
crystals in film emulsion consist of _____ & _____
silver bromide, silver iodide
latent img formation occurs during film _____
exposure
a contaminent in the SHC (silver halide crystal) creates the
sensitivity speck
the latent img can be seen?
only after development
the latent img is made up of _____ atoms
silver
high contrast film contains _____ SHC of _____ size
smaller, uniform
film is made w double emulsion to enhance film ______
speed
spectral matching is not a consideration when using?
direct exposure film (bc you need an IS)
storing film in very low humidity conditions can cause _______
static artifacts
film should be stored at a temp of _____ or below and w humidity no higher than ______.
a. 20ºF, 70%
b. 68ºF, 10%
c. 68ºF, 40%
d. 75ºF, 60%
c. 68ºF, 40%
the rollers in the auto processor are part of the ______ system
transport
replenishment of fixer and developer are controlled by the?
microswitch
the undeveloped silver halide is removed from the emulsion during?
fixing
which of the following is a rare earth phosphor? (zinc cadmium sulfite lanthanum oxybromide barium fluorohalide silver bromide)
lanthanum oxybromide
an increase in _____ will increase both beam qual. and quant.
kVp
what are the 4 primary exposure factors?
kVp, mA. time, and SID
changes in kVp affect (3)
OD, img contrast, img noise
an increase in mAs causes (an) _____ in beam qual. and (an) ______ in beam quant.
no change, increase
there is a direct relationship btw the quant. of XRs and the ________
milliamperage
if mAs are increased from 20 mAs to 40 mAs, the pt dose will….
be doubled
beam penetrability is increased if ____ is increased
kVp
beam qual. and beam quant. are increased by (2)
increasing kVp; (or going from single-phase to three-phase voltage)
beam qual. is improved when the _____ is increased, but the ______ has no effect on beam qual.
kV, mA
which technique would be best for reducing img blur?
a. 90 kVp/400 mA @ 0.01 sec
b. 85 kVp/50 mA @ 0.08 sec
c. 75 kVp/200 mA @ 0.02 sec
d. 65 kVp/100 mA @ 0.04 sec
a. 90 kVp/400 mA @ 0.01 sec
which techniques would give the highest pt dose?
a. 90 kVp/200 mA @ 0.02 sec
b. 87 kVp/400 mA @ 0.02 sec
c. 74 kVp/400 mA @ 0.04 sec
d. 65 kVp/300 mA @ 0.1 sec
d. 65 kVp/300 mA @ 0.1 sec
which imaging system provides the highest beam quantity? (3-phase, 12-pulse 3-phase, 6-pulse high frequency single phase, fully rectified)
3-phase, 12-pulse
added filtration has the effect of _____ the img quality and ______ pt dose
increasing, reducing
when all other exposure factors remain the same, changes in focal spot size result in ______ in beam quality and _____ in beam quantity
no change, no change
film can turn brown during storage due to retention of _________
ammonium thiosulfate
filtration is added to XR machines during manufacturing so that the required total of ____ mm Al equivalent filtration is achieved
2.5
radiographic _____ is random fluctuation in the OD of an XR
noise
what kind of film is used in mammo?
single emulsion film
an exposure w an off-level grid will show grid cutoff
across the img
what is the grid ratio of a grid w 3-mm height, 0.025-mm thick lead grid strips, and 0.3-mm thick interspace material?
10:1
what is the formula for Bucky factor?
pt dose w grid/pt dose without grid
grid ratio is the ____ of the grid strips divided by the width of the _______
height, interspace material
tree artifacts are caused by
friction
high contrast XR has what type of contrast?
short scale contrast
if a tech did a knee XR w a non-grid exposure using 10 mAs and wanted to use an 8:1 grid, what mAs should be used to produce an XR w the same density?
40
a tech did a lat C-spine using a 12:1 grid and 10 mAs. if the tech wants to repeat w/o a grid, what should the new mAs be to produce an XR w the same density?
2
if a tech uses 24 mAs w a 16:1 grid, how much mAs should they use w a 6:1 grid?
12
