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Week 3Image Production and evaluation > Image production and evaluation > Flashcards

Image production and evaluation Flashcards

1
Q

what factors provide a means for the radiographer to produce, review and evaluate radiographs

A

image quality factors

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2
Q

what are the 4 image quality factor

A

contrast
density
detail
distortion

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3
Q

this is the visible differences seen in adjacent anatomic structures on the radiograph

A

contrast

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4
Q

what results from the amount of penetration of the x-ray beam as it passes through different parts of the body

A

contrast

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5
Q

what have very few gray tones. They are mostly black and white

A

high contrast

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6
Q

High contrast is also known as

A

short scale contrast

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7
Q

images contain many shades of gray

A

low contrast

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8
Q

low contrast is also referred to as

A

long scale contrast

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9
Q

kV has an _ relationship to contrast

A

inverse

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10
Q

kV ^ contrast

A

goes down

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11
Q

what is the primary controlling factor for the penetrability of the x-ray beam and therefore directly controls contrast

A

kVp

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12
Q

as kV increases, x-ray penetrability of scatter radiation is _ causing more scatter to reach the image receptor

A

increase

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13
Q

high kV= _ contrast= _ scale contrast

A

low

long

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14
Q

low kV= _ contrast= _scale contrast

A

high

short

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15
Q

increase contrast by reducing the amount of scatter reaching the film

A

grids

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16
Q

limits the area being irradiated and thus reduces the amount of scatter being produced

A

beam restriction

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17
Q

less scatter= _ contrast

A

more

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18
Q

as OID increases, contrast _

A

increases

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19
Q

when OID increases contrast increases because a great deal of scatter radiation now misses the image receptor why

A

air gap technique

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20
Q

this is the amount of blackness on the radiograph

A

density

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21
Q

density is also known as

A

optical density

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22
Q

the amount of density on a film is controlled by

A
  1. the # of exit rays striking the film-screen striking the film-screen combination
  2. the speed of the film-screen combination
  3. processing
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23
Q

is the primary controlling factor for the quantity of x-rays being produced and therefore has a great deal of influence over the blackening of the image

A

mAs

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24
Q

is the primary controlling factor for the quality of x-rays being produced

A

kVp

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25
Q

more mAs= _ density

A

more

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26
Q

increasing kVp, _ photons frequency and _ photon wavelength, producing _ beam

A

increases
decreases
more powerful, penetrating

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27
Q

what is the secondary controlling factor of density

A

kVp

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28
Q

kVp is also known as

A

potential difference and electromotive force

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29
Q

increasing kVp, _ density and why

A

increases

because the more powerful beam doesn’t get attenuated in the body. more x-rays reach the image receptor

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30
Q

kVp affects density according to the

A

15% rule

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31
Q

if kVp increases by 15%, density is

A

doubled

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32
Q

if kVp decreases by 15%, density is

A

halved

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33
Q

A _% change in kVp will create a noticeable change in density on our image

A

4%

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34
Q

as film-screen speed increases, density

A

increases

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35
Q

as film-screen speed decreases, density

A

decreases

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36
Q

these decrease the amount of scatter reaching the film and thereby decrease density

A

grids

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37
Q

this decreases density by limiting the size of the x-ray beam and reducing the amount of scatter being produced

A

beam restriction

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38
Q

this affects density through its variation of atomic number and tissue thickness

A

anatomy

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39
Q

this affects density by altering tissue integrity and thickness

A

pathology

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40
Q

distance is affected by distance according to the

A

inverse square law

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41
Q

if distance (SID) is doubled, density

A

decreases 4 time

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42
Q

if distance (SID) is halved, density

A

increases 4 times

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43
Q

detail is also called

A

detail
sharpness
definition
image resolution

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44
Q

increasing OID= _ magnification= _ detail

A

increasing

decreasing

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45
Q

increasing SID= _ magnification= _ detail

A

decreasing

increasing

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46
Q

large focal spot size = _ in detail

A

decrease

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47
Q

small focal spot size = _ in detail

A

increase

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48
Q

large silver halide crystals in film = _ film speed = _ detail

A

fast

decreased

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49
Q

large phosphor crystals in intensifying screen = _ screen = _ detail

A

fast

decreased

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50
Q

any motion by the patient results in

A

image blur

loss of detail

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51
Q

this is the misrepresentation of an anatomic structure on an image receptor

A

distortion

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52
Q

there are 2 types of distortion

A

size

shape distortion

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53
Q

magnification makes anatomic structures appear larger on film than in reality

A

size distortion

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54
Q

Size distortion is caused by

A 
excessive OID ( major factor)
insufficient SID
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55
Q

shape distortion is divided into 2 categories

A

elongation

foreshortening

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56
Q

what makes structures to appear longer than they are in reality

A

elongation

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57
Q

elongation is is caused by

A

improper tube angulation

cassette alignment

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58
Q

what makes structures appear shorter than they are in reality

A

foreshortening

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59
Q

foreshortening is caused by

A

improper body part alignment with the cassette

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60
Q

there are 2 main types of technique charts

A
  1. fixd kVp charts

2. variable kvp charts

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61
Q

what are the most commonly used type of chart. For each anatomic part, an optimum kVp is selected. The mAs is then changed in order to accommodate changes in body part thickness

A

fixed kVp charts

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62
Q

have a set mAs value for each anatomic part and the kVp varies according to changes in body part thickness

A

variable kVp charts

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63
Q

is a device that measure the amount of radiation reaching the image receptor and then automatically terminates the exposure

A

AEC

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64
Q

There are 2 types of AEC devices

A
  1. Ionization chamber

2. photo timer

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65
Q

are the most commonly used AEC device. The gas filled chamber is located between the table top and the image receptor

A

Ionization chambers

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66
Q

utilize a fluorescent screen that is placed under the IR

A

phototimers

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67
Q

_ by the radiographer is of the utmost importance when using AEC

A

precise centering

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68
Q

_ have density control buttons that allow the radiographer to adjust the exposure to have more or less density

A

AEC devices

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69
Q

is a system in which the radiographer simply touches a picture or written description of the body part being imaged and the technique is set automatically

A

anatomically programmed radiography

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70
Q

_ is an important consideration when selecting film-screen combinations. The film and the intensifying screen must be sensitive to and emit the same color of light in order to work together efficiently

A

spectral matching

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71
Q

_ are sensitive to both blue and green light. These are used in radiography because we use rare earth intensifying screens which generally emit green light.

A

Orthochromatic films

72
Q

for Orthochromatic films, prior to 1970, calcium tungstate screens were used and they emitted a

A

blue/violet light

73
Q

Radiographic film has 2 main parts

A

the base

the emulsion

74
Q

most x-ray film has the emulsion on both sides of the base and is therefore called

A

double emulsion film

75
Q

double emulsion filme is used to

A

increase film speed

76
Q

The base of the film is made of _ and it is used to support the

A

polyester

emulsion

77
Q

the base is _ and has a _ tint

A

lucent

blue tint

78
Q

the emulsion consists of 2 main ingredients

A
  1. gelatin

2. silver halide crystals

79
Q

The gelatin is a clear substance that is used to hold the layer of _ in place

A

silver halide crystals

80
Q

the silver halide crystals are made of both

A

silver iodide and

silver bromide

81
Q

The size and concentration of the silver halide crystals determines the

A

speed of the film

82
Q

bigger crystals = _ film speed

A

faster

83
Q

films can also be designed to display different levels of contrast. The lower the contrast of a film, the _ the exposure latitude

A

wider

84
Q

this is the range of exposure techniques that can be used to produce an acceptable image

A

exposure latitude

85
Q

sensitometric curves, characteristic curves, and D-log E curves

A

H and D Curves

Hurter and Driffield

86
Q

H & D, this is a graphic representation of the relationship between

A

density and exposure

87
Q

In radiography, the useful range of optical density is between

A

0.25 to 2.5

88
Q

the closer the curve to the y axis, the faster the film

A

speed

89
Q

the steeper the curve, the _ the contrast

the more shallow the curve, the _ the contrast

A

higher

lower

90
Q

the steeper the curve, the _ the latitude.

the more shallow the curve, the _ the latitude

A

more narrow

the wider

91
Q

Less than _% of the radiographic image is created by x-rays striking the film

A

1

92
Q

Over _% of the image is made by light from the intensifying screens striking the film

A

99

93
Q

The main purpose of intensifying screens is to reduce pt dose by converting

A

x-rays into a great deal of visible light

94
Q

4 layers of film

A
  1. protective
  2. emulsion-silver halide, black metallic (active layer
  3. adhesive
  4. base
95
Q

4 layers of screen

A
  1. protective
  2. phosphor
  3. reflective
  4. base
96
Q

a screen that can produce a great deal of light is said to be a _ speed intensifying screen

A

high

97
Q

screen speed is detrained by

A

phosphor crystal size

thickness of phosphor layer

98
Q

bigger crystals= _ speed

A

faster

99
Q

thicker phosphor layer= _ speed

A

faster

100
Q

while bigger crystals and thicker phosphor layers _ patient dose, _ screen speed, _ image detail

A

reduce
increase
decreasing

101
Q

a rating of 100 is considered a

A

par speed screen

102
Q

anything rated below 100 is considered a

A

detail or extremity screen

103
Q

anything above 100 is a

A

high speed screen

104
Q

Before the invention of the automatic film processor, it took _ to completely develop a film

A

60 min

105
Q

The standard time to develop a film with an automatic processor is

A

90 sec

106
Q

the automatic processor has 3 separate tanks

A
  1. developer tank
  2. fixer tank
  3. wash tank
107
Q

the job of the _ is to change the exposed silver halide crystals into metallic silver. This creates the black and gray areas of the film

A

developer

108
Q

what stops the development process and makes sure that the image on the film doesn’t fade. It also clears all of the unexposed silver halide crystals from the film

A

fixer

109
Q

developer and fixer temperature is set at

A

95 degrees F

110
Q

what removes the chemicals that remain on the film

A

wash

111
Q

wash temperature is set at

A

90 degrees

112
Q

once the film has traveled through the 3 tanks, it is

A

blown dry in the dryer

113
Q

Dryer temperature is

A

120 degrees

114
Q

moves film through processor

A

transport

115
Q

replaces chemicals after film travel

A

replenishment

116
Q

regulates temperature

A

temperature regulation

117
Q

keeps chemicals from settling at bottom of processor

A

recirculation

118
Q

dries

A

dryer

119
Q

6 steps for the start up procedure

A
  1. close wash tank valve
  2. turn on water
  3. turn on processor
  4. put lid in place
  5. run several old 14 x 17 films
  6. wait for proper chemical temperatures
120
Q

4 steps for the shut down procedures

A
  1. turn off water
  2. turn off processor
  3. open wash tank valve
  4. leave lid open
121
Q

what is the measurement of the responses of film to exposure and processing.

A

sensitometry

122
Q

some of the tools used for sensitometry are

A

penetrometer
sensitometer
densitometer

123
Q

this may also be called a step wedge. Its used to produce a series of densities on a film by exposing it to x-rays. This is a method for monitoring both x-ray equipment and film-screen combinations

A

penetrometer

124
Q

this is designed to expose a reproducible, uniform, optical step wedge onto a film. It contains its own light source and is used for processor quality control

A

sensitometer

125
Q

this device provides a readout of the amount of blackening (density) on a film

A

densitometer

126
Q

each image is created in a square frame called a

A

matrix

127
Q

THe matrix is made up of small boxes that contain a numeric value. These boxes are called

A

pixels

128
Q

the numeric value of each pixel is converted into a certain amount of density that is then displayed on the monitor. The higher the numeric value of the pixel, the appears on the

A

screen

129
Q

the number of shades of gray that a digital system can display is called is

A

dynamic range

130
Q

the smaller the size of the pixels, the more of them that can be placed in the

A

matrix

131
Q

as more pixels are placed in the matrix,

A

image resolution increases

132
Q

the minimum acceptable resolution in digital imaging is a matrix size of

A

2048 x 2048

133
Q

each pixel represents a 3 dimensional volume of tissue that is called a

A

voxel

134
Q

the # of photons striking the detector

A

signal

135
Q

background information which is placed in the image but does not contribute to image quality

A

noise

136
Q

noise has the same appearance on the image as

A

quantum mottle

137
Q

is the comparison of these 2 characteristics on the image.

A

signal to noise ratio

138
Q

a signal to noise ratio is what and why

A

desirable

indicates little noise in the image

139
Q

what allows both the technologist and the radiologist to alter the image that has been produced in many different ways

A

post processing

140
Q

digital imaging has what vs conventional film

A

wider exposure latitude

141
Q

this adjusts both the contrast and the brightness of the image

A

windowing

142
Q

controls the contrast

A

window width

143
Q

when window level is increased, density

A

increased

144
Q

parts of the image can be magnified

A

magnification

145
Q

brightness can be increased along edges of structures

A

edge enhancement

146
Q

the removal of background anatomy to visualize contrast filled vessels

A

subtraction

147
Q

dark and light pixels are reversed

A

image reversal

148
Q

adding text to an image

A

annotation

149
Q

the numeric value that is representative of the amount of exposure the image receptor received. The number must be within a specific range in order for the image to be acceptable

A

exposure index

150
Q

the 2 types of digital imaging are

A 
Computed radiography (CR)
digital radiography
151
Q

uses a photostimulable storage phosphor imaging plate (PSP or IP) inside a cassette. This captures the latent image. The IP is then placed in an Image reader device (IRD)

A

computed radiography

152
Q

uses a laser beam to convert the image into an electronic signal that is then sent to the television monitor

A

image reader device (IRD)

153
Q

Layers of an imaging plate

A 
protective layer
phosphor layer
conductor layer
support layer
light shield layer
154
Q

insulates IP from trauma

A

protective layer

155
Q

active component of IP/ made of barium flourohalide bromides with europium activators

A

phosphor layer

156
Q

grounds the plate

A

conductor layer

157
Q

support base

A

support layer

158
Q

prevents light from erasing data

A

light shield layer

159
Q

what is much more sensitive to scatter than conventional film, so correct kVp and grid use is important

A

IP

160
Q

the latent image will lose _% of its energy in 8 hrs, so the image must be processed shortly after exposure

A

25%

161
Q

Does not use a cassette
directly converts the x-ray photons into an electrical signal.
the photons strike a flat panel detector that creates the conversion

A

digital radiography

162
Q

There are 2 types of digital radiography. They are separated by the type of flat panel detector they use

A

direct digital radiography

indirect digital radiography

163
Q

has an amorphous selenium flat panel detector. This releases electrons when struck by the x-ray photons

A

direct digital radiography

164
Q

has amorphous silicon flat panel detector. this detector requires a phosphor to create light when struck by x-ray photons. The light then causes the silicon to release electrons

A

indirect digital radiography

165
Q

Direct digital radiography advantage over indirect digital radiography ; direct digital radiography has the advantage of

A

creating a more accurate image because no divergent light beam (phosphor screen) is being used

166
Q

Indirect digital radiography has the advantage over direct digital radiography by

A

reducing patient dose because its phosphors work in the same way an intensifying screen

167
Q

both systems contain _ which collect the electrical charges and send the signal to the television monitor

A

Thin Film Transistors

168
Q

a disadvantage of both CR and DR when compared to conventional film

A

is a loss of resolution

169
Q

PACS stand for

A

picture archiving and communication systems

170
Q

incorporate the acquisition, storage, transmission and display of digital images into one computer network

A

PACS

171
Q

if an imaging center does not have digital imaging, actual films can be sent to a _ by using a film digitizer

A

PACS system

172
Q

the 2 types of film digitizers are

A

laser digitizers

charged coupled devices

173
Q

which is the least expensive and therefore the most commonly used film digitizer

A

CCD

174
Q

What does DICOM stand for

A

Digital Imaging and Communications in medicine

175
Q

what is a universal standard for the storage of medical images. This allows images to be passed back and forth on a PACS system, no matter who manufactures the imaging equipment

A

DICOM

Week 3Image Production and evaluation (1 decks)

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