Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Shani Radsci 226 > Test 2 > Flashcards

Test 2 Flashcards

1
Q

The recognizability factors in an image depend upon the ____ integrity of the projection

A

Geometrical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is penumbra present to some degree in all practical images?

A

Because no source of radiation is an infinitely small point, (all consist of areas).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The umbra of very small details in an image can completely disappear by what geometrical process

A

If the focal spot is significantly larger than the object being projected.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

misalignment of the x-ray beam, part and image receptor results in what undesirable image quality

A

Shape distortion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Given a 2mm focal spot size and SOD of 90 cm and on OID of 30 cm, what is the geometrical unsharpness of the image

A

0.67 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Given an 0.5mm focal spot and SID of 150 cm and an OID of 15 cm what is the geometrical unsharpness of the image

A

0.055 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the relative sharpness for an SOD of 90 cm and an OID of 15 cm

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

an original exposure used an SOD of 120 cm and OID of 12 cm. IF the SOD is increased to 150 cm and the OID is reduced to 10 cm by what factor will the sharpness be improved

A

By 1½ times or 50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

With an SID of 60 cm and an OID of 40 m by what factor will the image be magnified

A

3 X

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

an image measures 16cm across. A 60 cm SID was used with an SOD of 40 cm. What is the size of the original object

A

3 X

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the percentage magnification for an image with a magnification factor of 1.44

A

44%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The radiographic image of a particular bone turns out 4 times longer than the real bone, but only 2 times wider. what is the factor of magnification? what is the factor of shape distortion

A

Magnification = 2 X; Shape distortion = 2 X

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The resolution of line pairs from a test template can be reduced by either of which two processes

A

Blurring or loss of contrast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The ability to distinguish any two adjacent details as separate and distinct details is the definition for what aspect of an image

A

Resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the typical range of anode bevel angles fro a general purpose x-ray tube

A

15-17 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

rather than using the line-focus principle, why don’t we just focus down the beam of electrons so that the actual focal spot is 0.5 mm

A

Because this would damage the anode by concentrating the heat load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

the projected focal spot is largest at the end of the ___ image receptor

A

Cathode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

explain why the anode heel effect occurs

A

Because the anode material itself acts as a filter for x-rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

x-ray tubes are conventionally installed with the anode to your ____ as you approach the x-ray table

A

left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

for a radiograph of the AP foot or femur, it is best to position the patient on the x-ray table with his head to your _____

A

right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

at a shorter SID, the collimator must be opened up to cover the same field size, so the anode heel effect ____

A

increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the most compelling reason to consider focal spot size as the controlling factor for sharpness in the remnant beam images

A

The focal spot affects only image sharpness, it does not affect any other image qualities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

why is the small focal spot not available when high mA stations are engaged

A

It is locked out from these high mA stations to prevent overloading the anode with concentrated heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

the actual focal spot is best measured along the

A

Beveled anode surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

explain how a focal spot which is much larger than an anatomical detail can cause it to disappear from the resolved image

A

When the focal spot is substantially larger than an image detail, the penumbra can spread so much inward that the umbra portion of the image is completely lost.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

If the size of the focal spot is cut exactly in half, the sharpness of the image carried by the remnant x-ray beam will change which way and by precisely how much

A

Sharpness will increase to precisely double the original

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

where within the penumbra does the human eye locate the edge of an image detail

A

At the center of the penumbra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

geometrical penumbra is caused by the ____ absorption of xrays as a function of the total absorption which the anatomical structure is capable of

A

Partial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

decreasing the SID _____ penumbra

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

list four benefits of increased SID

A

1) Patient dose is slightly reduced, 2) Spatial resolution (sharpness) is improved,3) Magnification of anatomy is reduced, 4) More anatomy can be included within the field of view

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

if a change in the SID has resulted in the exposure increasing by 4 times, all other factors equal, the SID must have been changed by what amount?

A

It must have been cut to ½ the original

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

a technique chart lists 0.05 second for a procedure using 100 cm SID at a new SID of 200 cm, what new time would be required to maintain the exposure at the image receptor

A

0.2 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

for any change greater than ____ percent in the SID, radiographic technique factors should be adjusted to compensate and maintain exposure

A

15%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

when changing from 180 to 100 cm, change the mAs to ____ the original

A

1/3 (0.31)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

image sharpness is directly proportional to which radiographic distance

A

SOD (source-to-object distance)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

in the interest of image sharpness, generally the ____ Feasible SID should be used

A

Maximum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

as a rule-of-thumb, when changing from a 100cm SID to a 125 cm SID, increase the mAs by ______

A

One step

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

an SID of 128 cm results in an exposure at the receptor plate of 10 mGy, Using the inverse square law if the SID is changed to 92 cm, what will the new exposure be

A

19.4 mGy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

at an SID of 244cm, 120 ma results in a satisfactory exposure. if the SID is changed to 75 cm what new mA must be sued to maintain the exposure at the receptor plate

A

11.4 mA (approximately 10 mA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

at an SID of 200 cm, 25 mAs results in a satisfactory exposure. If the SID is changed to 90 cm , what new mAs must be used to maintain the exposure at the receptor plate

A

5.06 mAs (approximately 5 mAs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

in general radiography, the ____ possible OID should always be used

A

Minimum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

The greater the OID the ___ the subject contrast in the remnant beam image

A

Greater

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

The greater the OID the ____ the sharpness of detail in the image

A

Less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

at greater OID, ____ radiation is allowed to spread out more, while ____ radiation remains at the same concentration

A

Secondary or scatter; primary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

magnification is directly proportional to the ____ ratio

A

SID/SOD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

image sharpness is directly proportional to the ____ ratio

A

SOD/OID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

If the SID is 100cm and the SOD is 50cm , the projected image of the object will be magnified by a factor of _____

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

an original technique uses an SID of 100 cm and an OID of 5cm. If the OID were increased to 7.5cm what new SID would be required in order to completely eliminate the blurring effects of the OID change

A

150 cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

an original magnification ration is 50 percent. if the SID and OID are both tripled, the new magnification ration will be _____

A

50% (the same)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

if both SID and OID are increased by 15 cm, what will be the net effect on the exposure intensity at the image receptor plate

A

Decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

If both SID and OID are increased by 20 cm, what will be the net effect on the subject contrast in the image at the receptor plate

A

Increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

why is off centering of the CR identical in its effects to angling the x-ray beam

A

Because it places objects into diverging beams which are at an angle to the CR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

why do positioning atlases recommend a 15-degree angle for the AP projection of the sacrum, when the sacrum actually lies at 30-35 degree angle

A

To minimize shape distortion (and to desuperimpose the symphysis pubis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

which of the following would be most distorted by a 30 degree CR angle: the head of the femur, the shaft of the femur, or the sternum

A

The head of the femur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

if a flat object is tilted in relation to the receptor, and the CR is angle perpendicular to the object, what type of distortion if any occurs

A

Elongation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

the distorting effects of off centering are indirectly worsened when the SID is _____

A

Decreased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

If the R is angled 20 degrees, the TTD should be changed from 100 cm to ___ in order to maintain the exposure level

A

90 cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

List the four aspects of beam part receptor alignment which impact upon shape distortion

A

1) Shape and size of the object, 2) centering of the object relative to the x-ray beam, 3) angle formed between the object and the x-ray beam, 4) angle formed between the object and the image receptor plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

why does the cranium distort more than the head of the femur with an angled projection

A

Because of the cranium’s much greater thickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

what is the angle of x-ray beam divergence at a point 10 m cephalic to the CR

A

7 degrees (cephalic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

for a lateral projection of the lumbar spine, why is it not desirable to build the spine up all the way to a horizontal position

A

Normal divergence of the x-ray beam lines up with the intervertebral joint spaces when there is slight sag in the spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

what are the four geometrical objectives of radiographic positioning

A

1) Desuperimpose obstructing anatomy, 2) minimize magnification, 3) minimize distortion, 4) maximize sharpness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

why are multiple projections at different angles necessary for fracture radiogrpahy

A

To fully demonstrate alignment of bones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

contrasty anatomy that obscures the anatomy of interest is a form of image ____

A

Noise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

penumbra in the image is ____ by motion of the par, x-ray tube or recptor

A

Increased (spread)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

how might eh x-ray tube accidentally be moving during an exposure

A

If it is not locked in place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

by superimposing various image densities, severe motion can destroy image ___ as well as sharpness

A

Contrast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

streaks or circular artifacts caused by tomographic movement are classified as ____ images

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

list the three methods of minimizing motion during radiographic exposures

A

1) Minimal exposure time, 2) securing patient cooperation, 3) use of mechanical restraining devices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

to freeze motion, exposure time should not exceed ___ second

A

0.033 (1/30) second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What are the three components of recognizability

A

sharpness, magnification, shape distortion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

what does SID stand for

A

source to image distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

what does SOD stand for

A

source to object distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

what does OID stand for

A

object to image distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

another name for sharpness of detail

A

spatial resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

area on the anode where the electrons hit

A

actual focal spot size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

if the angle of the bevel increases the focal spot ____

A

increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

the clearly defined portion of a projected image

A

umbra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

blur along the edges of an image

A

penumbra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

formula to calculate for penumbra

A

penumbra = Fs x OID/ SOD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Smaller focal spot sizes produce ____ penumbra which in turn produces better ____ _____

A

less, spatial resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Why do we not use a small focal spot size for all images

A

it burns out the anode due to too much heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

If we increase SID what does it do to spatial resolution

A

increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

if we increase SID what does it do to magnification

A

decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

what is the formula for magnification factor

A

image size/ object size or SID/SOD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

what is the formula for object size

A

image size (SOD/SID)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

what two types of distortion are there

A

magnification and shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

Changes in SID changes on the ___ on the x-ray beam

A

intensity

89
Q

Changes in SID do not affect the ____ or the ____ of the x-ray beam

A

energy or penetrability

90
Q

What ratios of interactions are unchanged by the change in SID

A

absorption, transmitted and scatter

91
Q

True or false. Changes in SID affect subject contrast of an image

A

false

92
Q

Principle that exposure at the image receptor can be maintained for difference SIDs by changing the mAs by the square of distance changed

A

square law

93
Q

An increase in OID ____ magnification

A

increases

94
Q

and increase in OID _____ spacial resolution

A

decreases

95
Q

an increase in SID ___ patient skin exposure

A

reduces/decreases

96
Q

what geometrical component should be maximized in an exposure

A

sharpness

97
Q

what geometrical component should be minimized in an exposre

A

magnification and shape distortion

98
Q

relative sharpness in a radiographic image is proportional to the ratio:

A

SOD/OID

99
Q

True or false: high contrast is the same has high spatial resolution

A

false

100
Q

true or false: blur is the same as low contrast

A

false

101
Q

Radiographic magnification is proportional to the ratio:

A

SID/SOD

102
Q

In order for magnification to be present, the ____ of the image must be expanded

A

umbra

103
Q

the overall quality of an image, and the ability to distinguish adjacent details as being separate and distinct from one another

A

resolution

104
Q

when one dimension of the image is changed by a different amount than the other this is considered

A

shape distortion

105
Q

the two most important components or resolution are

A

contrast and sharpness of detail

106
Q

what principle uses steep anode bevel angles to project an effective focal spot that is much smaller than the actual focal spot

A

line-focus principle

107
Q

Because of the line-focus principle the projected focal spot is smaller toward the ___ end of the x-ray tube

A

anode

108
Q

the ___ end of the x-ray tube produces a sharper image

A

anode

109
Q

which end of the x-ray tube produces less radiation

A

anode

110
Q

what effect results in less radiation being emitted at the anode end of the x-ray tube

A

anode heel effect

111
Q

the thinnest portion of the anatomy should be at what end of the x-ray tube

A

anode

112
Q

the thickest portion of the anatomy should be at what end of the x-ray tube

A

cathode

113
Q

what 4 things affect the anode heel effect

A

steeper anode bevels, larger focal spots, shorter SID, longer field size

114
Q

the size of the projected focal spot is directly proportional to ____ and inversely proportional to the _______ produced in the remnant beam image

A

penumbra, sharpness

115
Q

produced by rays from different portions of the focal spot recording the same detail edge in different locations at the recptor

A

penumbra

116
Q

penumbra causes ____ to shrink

A

umbra

117
Q

if an anatomical detail of interest is significantly smaller than the focal spot used, what happens to it?

A

It may not be resolved in the image and will disappear from view

118
Q

True or false: Focal spot size has no effect upon image magnification

A

true

119
Q

true or false : Focal spot size has an effect on distortion

A

false

120
Q

The focal spot affects image ____ exclusively

A

sharpness

121
Q

what effects image sharpness exclusively and is the only radiographic variable that does so?

A

focal spot

122
Q

what is the controlling factor at the detector for image sharpness

A

focal spot

123
Q

what focal spot should always be engaged for smaller anatomical parts?

A

small

124
Q

what portion of the human body can be used to estimate an SID if a tape measure it not available

A

wingspan

125
Q

a longer SID ____ penumbra

A

reduces/ decreases

126
Q

A longer SID_____ the sharpness of recorded detail

A

increases / enhances

127
Q

increasing the SID _____ the SOD

A

increases

128
Q

A longer SID ____ magnification

A

reduces/decreases

129
Q

increased SID allows for a ____ field of view to be included with the area of the image receptor

A

larger

130
Q

the inverse square of the distance reduces the exposure _____ at the receptor plate

A

intensity

131
Q

x-rays spread out _____

A

isotropically

132
Q

any changes great than ___ percent in SID should be compensated for by adjusting technique

A

15 percent

133
Q

The adjustment of radiographic technique for changes in SID follows the _____ _____

A

square law

134
Q

True or false. The SID has no direct impact upon image contrast or shape distortion

A

true

135
Q

What does SSD stand for

A

source to skin

136
Q

True or false SSD changes by a greater ratio than the SID

A

True

137
Q

true or false. Increased SID can be used to reduce patient skin dose

A

true

138
Q

True or false. OID impacts shape distortion

A

false

139
Q

true or false. OID impacts every image quality except shape distortion

A

true

140
Q

Increasing the OID enhances ______ _____ in the remnant beam image

A

subject contrast

141
Q

Increasing OID ______ the total exposure at the image receptor

A

lessens

142
Q

Increasing OID causes the spread of ______ and reduces ______

A

penumbra, sharpness

143
Q

Increasing OID ____ magnification

A

increases

144
Q

magnification is proportional to the _____ ratio

A

SID/SOD

145
Q

Sharpness of recorded detail in the image is proportional tot he ____ Ratio

A

SOD/OID

146
Q

Misalignment of the CR, part or receptor can produce what kind of error

A

part distortion

147
Q

____-____ results in identical effects as angling the beam

A

off-centering

148
Q

angling or off-centering on spherical or cuboidal objects will often cause ____

A

elongation

149
Q

flat, tubular, or wedge shaped objects tilted in relation to the CR and receptor will undergo _____ distortion

A

foreshortening

150
Q

angling the CR perpendicular to an object which is tilted in relation to the receptor will cause ____ distortion

A

elongation

151
Q

flat or linear objects kept ______ to the receptor may not be visibly distorted by CR angles

A

parallel

152
Q

True or false CR angulation has no effect upon subject contrast

A

true

153
Q

T or F CR angulation has an effect on magnification

A

false

154
Q

t OR f CR has no effect on sharpness of detail

A

true

155
Q

what is the most destructive factor for sharpness of recorded detail in the remnant beam image

A

motion

156
Q

severe motion can destroy subject contrast by

A

superimposing various densities

157
Q

t or f motion can create false images

A

true

158
Q

t or f motion has a direct relationship to brightness

A

false

159
Q

t or f motion has no direct relationship to magnification

A

true

160
Q

t or f motion has no direct relationship to shape distortion

A

true

161
Q

To freeze motion, exposure times should not exceed ____ seconds

A

.033

162
Q

what three factors affect the anode heel effect

A

SID, cassette size, focal spot size

163
Q

what three components make up the geometrical integrity or recognizability of an image

A

sharpness, magnification, shape distortion

164
Q

abruptness with which the edges of a particular image stops

A

sharpness

165
Q

another name for sharpness

A

spatial resolution

166
Q

The ARRT definition for the sharpness of the structural edges recorded in the images

A

spatial resolution

167
Q

what source of light produce edges with no blur, and there are few in nature

A

point source

168
Q

what source of light is an example of sunlight

A

disk source

169
Q

what source of light is an example of headlights and flashlights

A

area sources

170
Q

inner portion of a shadow that hos a uniform darkness

A

umbra

171
Q

pure portion of a shadow

A

umbra

172
Q

blurry fading partial shadow projected at each edge

A

penumbra

173
Q

blurriness, unsharpness

A

penumbra

174
Q

as penumbra increases, umbra _____

A

decreases

175
Q

When penumbra from two adjacent objects overlap and deceptively appear as the shadow of one object

A

geometrical penumbra

176
Q

motion of the source of light, the object or the recording surface

A

motion penumbra

177
Q

motion penumbra spreads penumbra ______ such that its ____ is expanded

A

laterally, width

178
Q

another name for magnification is

A

shape distortion

179
Q

difference between the size of the real object and the size of its projected image

A

magnification

180
Q

For magnification to be present what portion of the image must be larger?

A

umbra

181
Q

If the penumbra is enlarged is this considered magnification?

A

no, just more blurring

182
Q

difference between the shape of the real object and the shape of its projected image

A

shape distortion

183
Q

what must be altered for shape distortion to have occured

A

the length and width of the object by different degrees

184
Q

what two variation of shape distortion can occur

A

foreshortening and elongation

185
Q

what can cause shape distortion

A

off-centering, angulation, misalignment

186
Q

sharpness can only be measured by what method

A

indirectly by directly measuring the unsharpness

187
Q

unsharpness is controlled b what three things

A

SOD, OID, and focal spot size

188
Q

What is the formula to calculate penumbra

A

penumbra = fsxoid/sod

189
Q

T or F high contrast is equal to better sharpness

A

false

190
Q

T or F Scatter radiation does not affect sharpness

A

True

191
Q

what two factors control sharpness

A

Prevention of motion, use of optimum geometry (OID, SID, SOD and focal spot)

192
Q

When both the length and the width of the image will measure larger than the real object by equal proportions

A

magnification

193
Q

what ratio is SID/SOD

A

magnification

194
Q

If the length of the image measures longer than that of the real object it is considered to have what kind of shape distortion

A

elongation

195
Q

if the width of the image measures wider than that of the real object it is considered to have what kind of shape distortion

A

foreshortening

196
Q

the total amount of useful information present in an image

A

resolution

197
Q

The angle of the target surface of the anode in relationship to a vertical line drawn perpendicular to the long axis of the x-ray tube.

A

Anode Bevel

198
Q

Effects the size of the effective focal spot and the distribution of x-ray intensity within the beam

A

anode bevel

199
Q

The smaller the focal spot size the ____ the sharpness

A

greater/ better

200
Q

the _______ focal spot can be made smaller than the actual stream of electron

A

effective

201
Q

where is the true actual focal spot measured

A

along the beveled anode surface

202
Q

In terms of the line-focus principle, what aspects effect the sharpness of the radiograph?

A

the size of the filament, the angle of the anode bevel

203
Q

The area available for the dispersion of heat generated in teh anode from the colliding electrons

A

actual focal spot

204
Q

achieve goal of very small effective focal spot while allowing at the same time the anode heat to disperse over a sufficient area

A

line-focus principle

205
Q

which end of the x-ray tube produce sharper images

A

anode end

206
Q

a variation in the x-ray intensity along the longitudinal tube axis

A

anode heel effect

207
Q

The anode heel effect is more pronounced with what field and focal spot sizes

A

large

208
Q

The thinner size of anatomy should be place at what end of the x-ray tube

A

anode

209
Q

the lower back corner of the anode disc

A

heel

210
Q

what diminishes toward the anode side of the x-ray beam

A

the intensity of the beam

211
Q

The anode acts as a for of ____ filtration

A

inherent

212
Q

______ the SID spreads out the effects of the anode heel effect

A

increasing

213
Q

Shorter SID _____ the effects of the anode heel effect

and ____ the effects

A

Concentrates, amplifies

214
Q

what three things have an affect on the anode heel effect

A

cassette size, focal spot size, and SID

215
Q

focusing of the electron beam in the x-ray tube down onto a small area on the anode target surface

A

focal spot

216
Q

spot “seen” from the viewpoint of the image receptor (1mm)

A

effective focal spot

217
Q

the smaller the focal spot the ______ the recorded detail

A

sharper

218
Q

focal spot is ______ proportional to recorded detail

A

inversely

219
Q

The three variables that control the projected geometrical sharpness of details in the image:

A
  1. SOD
  2. OID
  3. Focal Spot Size

Shani Radsci 226 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions