film screen radiography Flashcards
(144 cards)
1
Q
The ____ beam refers to the x-rays that remain as the useful beam exits the pt. It consists of x-rays scattered away from the IR and image-forming x-rays.
A
exit
2
Q
The medium that converts the x-ray beam into a visible image is called the _____ ________.
A
image receptor
3
Q
The two basic components of radiographic film are the ________ and the __________.
A
base and emulsion
4
Q
Modern radiographic film base is made of __________.
A
polyester
5
Q
How thick is radiographic film base?
A
150-300 um
6
Q
The important characteristics of radiographic film base are lucency and
A
dimensional stability
7
Q
The main purpose of the gelatin emulsion in radiographic film is to
A
hold the silver halide crystals
8
Q
Crystals in film emulsion consist of __________ and ___________.
A
Silver bromide and silver iodide
9
Q
The overcoat on radiographic film is a protective covering of ____________.
A
Gelatin
10
Q
Latent image formation occurs during film _________.
A
exposure
11
Q
A contaminant in the silver halide crystal creates the
A
Sensitivity speck
12
Q
Direct exposure film has a _______ emulsion and _______ silver halide crystals than screen-film.
A
Thicker ,more
13
Q
The latent image can be seen
A
only after development
14
Q
Photon interactions free the electrons from __________ atoms in the silver halide crystal.
A
Both A and B . Bromide and iodide
15
Q
The latent image is made up of _________ atoms.
A
Silver
16
Q
Photon interactions in the emulsion occur with exposure to ________.
A
Both A and B. X-rays and light?
17
Q
The most commonly used radiographic film is __________.
A
Screen film
18
Q
The size, shape, and distribution of silver halide crystals determine _________ of screen-film.
A
Speed, contrast , and sensitivity
19
Q
The contrast of film is inversely proportional to its ______.
A
Latitude
20
Q
High contrast film contains _______ silver halide crystals of ______ size.
A
Smaller and uniform
21
Q
Film is made with double emulsion to enhance film __________.
A
Speed
22
Q
Spectral matching is not a consideration when using
A
Direct exposure film
23
Q
Orthochromatic film is used with rare earth screens because of its sensitivity to ________ light.
A
Green
24
Q
What is a reasonable maximum storage time for radiographic film?
A
45 days
25
Film fog on unprocessed film will occur with radiation exposure as low as _______.
0.2 mr
26
Storing film in very low humidity conditions can cause
Static artifacts
27
Film should be stored at a temperature of _____ or below and with humidity no higher than
68 F , 40%
28
The layer of screen that lies closest to the film is the _______________.
Protective coating
29
The light-emitting efficiency of the intensifying screen is improved by the
Reflective layer
30
Screen characteristics are determined by
All of the above. Size of phosphor crystals, thickness of phosphor layer, & phosphor composition
31
A phosphorescent material emits light
For a period of time after stimulation
32
An intensifying screen is an example of _______________.
Luminescence and fluorescence
33
Luminescent material emits light after its outer shell electrons are
Excited
34
A screen that emits light after an exposure terminates is exhibiting
screen lag
35
The intensification factor is a measurement of screen _________.
Speed
36
The intensification factor is the exposure required ___________ divided by the exposure required ___________.
Without screens , with screens
37
The intensification factor increases with increased ____________.
Kvp???
38
The ability of an intensifying screen to absorb x-rays is called
Detective quantum efficiency
39
Image noise is increased with increased
Conversion efficiency
40
What is the formula for conversion efficiency?
CE= (emitted light/ # of X-rays absorbed) x 100
41
Both the isotropic emission of light from screen phosphor crystals and the added reflective layer contribute to
Image blur
42
Spatial resolution is improved when a screen has
Added absorbing dye
43
Image blur is generally increased by any factor that increases the
Intensification factor
44
A fine detail screen can resolve ___ lp/mm.
15
45
About ___% of the latent image on the film is created by light from the screens.
99%
46
The use of screens greatly increases
Tube life
47
The back cover of the cassette is usually made of ______ material to reduce backscatter.
High z
48
A disadvantage of the speed of rare earth screens is the increase in
Quantum mottle
49
Intensifying screens wear out because of
Improper handling
50
If a film is used without spectral matching, the result would be a reduction in
Optical density
51
In a busy department, screens should be cleaned ______.
Monthly
52
An annual wire mesh test is needed to check for
Worn felt contacts
53
Film that has emulsion coated on both sides is called what?
double-emulsion film
54
Between the emulsion and the base is a thin coating of material called the ________ _____, which ensures uniform adhesion of the emulsion to the base.
adhesive layer
55
The ________ layer allows the emulsion and the base to maintain proper contact and integrity during use and processing.
adhesive
56
The emulsion is enclosed by a protective covering of gelatin called the ________.
overcoat
57
What is the most commonly used radiographic film type?
screen-film
58
After an interaction of the x-ray is either totally absorbed or partially absorbed. If it is totally absorbed it is called?
photoelctron
59
After an interaction of the x-ray is either totally absorbed or partially absorbed. If it is partially absorbed it is called?
compton
60
The phosphor converts the xray beam into...?
Light
61
During WWI when glass became largely unavailable, what became its substitute as film base? What is this substitute's deficiency?
Cellulose nitrate ; it's flammable
62
By the mid-1920s, a new "safety base" for film was introduced. What material was it made of?
cellulose triacetate
63
The emulsion consists of a homogeneous mixture of _______ and ______ ______ ________.
Gelatin and silver halide crystals
64
The emulsion layer of film is _ to _ µm thick.
3 to 5
65
_______ grains are used in most radiographic films.
Tabular
66
High ratio grid has higher/lower contrast improvement factor ?
Higher
67
The higher the grid ratio the higher/lower is the Bucky factor
Higher
68
Bucky factor increases with increasing/decreasing Kvp
Increasing
69
What is the purpose of a moving grid
To remove grid lines
70
What are the different types of grid motions used ?
Reciprocating and oscillating grid
71
How will the image appear if the grid is off level?
Grid cutoff across image, underexposed, light image (loss of density ). Same as of center
72
How will the image appear if the grid is off center ?
Grid cutoff across image, underexposed, light image (loss of density ) same as off level
73
How will the image appear if the grid is of focus?
Grid cutoff on one side of the image
74
How will the image appear if the grid is placed upside down?
Grid cutoff toward the edge of the image
75
You can improve the image contrast on a heavy patient without increasing the patient dose by
Tight collimation
76
Beam restriction with an ....... Is only accurate at a fixed SID.
Aperture diaphragm
77
Higher kvp .......patient dose.....and image contrast.
decreases, decreases
78
The most commonly used beam restricting device is the.....?
variable collimator
79
The use of a compression device will increase .......on the image.
Contrast
80
Photoelectric interactions increase when ......is decreased.
kvp
81
What are the three best ways to improve contrast resolution?
?
82
The three primary factors influencing the intensity of the scatter in the image forming bean are :
Kvp,field size, and patient thickness
83
Quantum mottle is controlled by
mAs
84
In long scale contrast density is
Increased
85
In short scale contrast density is
Decreased
86
Voltage ripple:
High frequency < 1 %
Half wave 100%
Full wave 100%
3 phase 6 pulse 13% 12 pulse 4%
87
Name the 4 types of body habitus
Hypersthenic (5%)
Sthenic(50%)
Hyposthenic (35%)
Asthenic(10%)
88
The main disdvantage of parallel crossed _________
Grid cutoff
89
Focal spot blur can be reduced by using a ______ focal spot, large SID, small OID.
Small
90
The 3 prime geometric factors affecting image quality ________
magnification,distortion, forcal spot blur
91
In general radiography, the useful optical densities lie between _____and ______
0.25-2.25
92
An IR with ______ can be used over greater image range of exposure
Wide latitude
93
Spatial resolution improves with decreased ___________________________
screen, motion, geometric blur
94
WIth automatic exposure control (AEC) the exposure is terminated when the optimum _____is reached.
OD
95
Sharpness of detail can be improved by increasing ______
SID
96
At least a ______ change in mAs is necessary to produce a visible change in OD.
30%
97
Using high frequency and or high ratio grid results in ____________patient radiation dose.
increase
98
The use of ________ imprves contrast and reduces patient does.
collimation
99
The main diadvantage of parallel crossed _________
Grid cutoff
100
Define contrast resolution
The ability to distinguish anatomic structures of similar subject contrast such as liver and spleen
101
The main components of film are:
base, adhesive, emulsion, supercoat
102
This is applied on the base layer before emulsion.
adhesive
103
Diagnostic radiographic film with emulsion on both sides is termed:
Duplitized,Double Emulsion, or Double Coated. Answer is all of the above
104
What is the correct order of the processing process:
Developer, Fixer, Washer, Dryer
105
High ratio grid improves
radiographic contrast
106
The higher the grid ratio
The higher the contrast improvement factor
107
Bucky factor increases with ...... kvp
Increasing
108
The use of a compression device will increase
Contrast
109
Purpose of grid
To improve image contrast
110
Optical density is directly controled by the changing
mAs
111
The use of .......improves contrast and reduces patient dose
Collimation
112
Purpose of moving grid
to remove grid lines
113
High grid ratio increases....... and............, and decreases.............
patient dose,grid cutoff, and positioning latitude
114
Destructive
radiolucent
115
Constructive
Radiopaque
116
Intensifying screen increases............, decreases..........and...........
density, patient dose, and detail
117
How can you reduce motion blur?
short exposure time
118
The image after processing is known as
manifest image
119
What does grid cutoff mean?
The primary x rays are absorbed
120
Radiograpgic grid with ines running in two directions
Crossed
121
Whwn mA is increased what must be done to exposure time in order to maintain the same exposure?
decrease time
122
What is the purpose of the fixer in an automatic processor?
remove the unexposed silver halide crystals
123
When is xray film most sensitive to safelight illumination?
after exposure
124
Poor film-screen contact will cause which of the following effects?
Unsharpness
125
Which of the following could be the cause of poor film-screen contact?
warped cassette, worn backing in the cassette, and damaged latch on the cassette
126
Which grid removes more scatter radiation?
Crossed
127
Which of the following influences geometric unsharpness?
OID
Focal-Object Distance
SID
128
Distortion can be caused by
Tubes Angle
The Position of The organ or Structure Within The Body.
The Radio graphic Positioning of The Part.
129
The major function of filtration is to reduce
patient dose
130
Which of the following will influence recorded detail?
1) Screen Speed
2) Screen/Film Contract
3) Focal Spot
131
What will result from using single-emulsion film in an image receptor having a two intensifying screens?
Decreased Density
132
Boxes of film stored in too warm an area may be subject to
film fog
133
X-ray film emulsion is most sensitive to safelight fog
| .
After Exposure.
134
The absorption of useful radiation by a grid is called
grid cutoff
135
The unwanted exposure of film by environment is called:
chemical fog
136
Primary cause for contamination is:
Other chemicals have mixed with the developer
137
The part of processing that is most affected by contamination is:
developer
138
This artifact is caused by static electricity and happens in low humidity:
trees
139
This occurs when screen phosphors continue to emit light after the x-ray exposure has stopped:
phosphorescence
140
...........% change in mAs is required for a perceptible change in OD.
30%
141
............% change in kVp is required for a perceptible change in OD.
4%
142
..............% increase in kVp will double the OD (15% rule)
15%
143
What is the formula for OD?
OD=log 10 Io/It
144
The base + fog of a film is shown below the _______ of characteristic curve
toe portion
