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RAD 354 > Test 1 > Flashcards

Test 1 Flashcards

1
Q

what is an example of molecular effects of irradiation

A

any visible signs of molecular/cellular damage
ex. radiation burns

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2
Q

results from molecular damage

A

formation of structurally changed molecules that may impair cell functions

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3
Q

classifications of cell effect from radiation

A

direct
indirect

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4
Q

where does energy transfer for direct action

A

direct energy transfer to macromolecules

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5
Q

effect of direct action?

A

ionizing particles directly effect macromolecules –> making them inactive or alters function

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6
Q

likeliness of direct action occurring? occurs most often with what?

A

very low –> 1%
more likely with high-LET, particulate radiation, or alpha radiation

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7
Q

why is direct action less likely to occur?

A

atom is mainly space = less occurrence to interact

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8
Q

what damage does direct action cause?

A

double strand break or single strand break = cell death

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9
Q

why is indirect action most likely to occur?

A

interacts with water (most abundant molecule)

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10
Q

what is radiolysis of water

A

indirect action radiation that breaks apart water and creates free radicals

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11
Q

what causes damage in indirect action

A

free radicals transferring energy to macromolecules

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12
Q

what type of radiation is indirect and direct

A

indirect = secondary
direct = primary

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13
Q

all effects of irradiation in living cells come from?

A

indirect action

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14
Q

what is a macromolecule?

A

building material in DNA

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15
Q

what is a free radical

A

atom/molecule that has a single, unpaired orbital (valence) electron

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16
Q

characteristic of free radical (3)

A

highly reactive
possible result of cell death
short lifespan

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17
Q

free radicals can cause damage by

A

ionization
excitation
creation of toxic substances (peroxide/superoxide)

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18
Q

cellular effects of irradiation is characterized by?

A

amount of radiation given
type of radiation

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19
Q

types of affects from ionizing radiation (7)

A

Instant death
reproductive death
apoptosis
mitotic death
mitotic delay
permanent or temporary interference with function
chromosome breakage

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20
Q

energy transfer in ionizing radiation

A

energy transfer to cell’s nucleus

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21
Q

instant death
amount
effect

A

amount: 1000+ Gy/sec
effect: disrupts cellular form, structure, chemistry

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22
Q

reproductive death
amount

A

amount: 1-10 Gy

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23
Q

apoptosis
effect

A

cells die without dividing –> programmed cell death
can occur with or without exposure to radiation

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24
Q

mitotic death
effect

A

cells die after 1-2 divisions

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25
Q

mitotic delay
amount
effect

A

amount: 0.01Gy
effect: failure for cell to divide in time

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26
Q

chromosome breakage
effect

A

ionizing radiation interacts with DNA = loss of genetic material = mutations

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27
Q

point mutation
occurs with?
can be repaired?

A

occurs with low-LET
Yes by action of repair enzymes

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28
Q

double strand breaks
occurs with?
can be repaired?

A

occurs with high-LET
Less likely to be repaired

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29
Q

Target theory

A

when cell DNA is directly or indirectly inactivated by exposure to radiation = cell death

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30
Q

when was the British X-ray and Radium Protection Committee created?

A

1921

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31
Q

British X-ray and Radium Protection Committee
Purpose?
Flaw?

A

Purpose: creates guidelines for manufacturers and use of radium/x-ray equipment
Flaw: no accurate measuring techniques or background knowledge

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32
Q

Skin erythema dose
purpose?
flaw?

A

Purpose: measured radiation exposure by physical appearance of redness over an area of skin
Flaw: inaccurate measurement –> erythema reaction varied from person to person

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33
Q

when was SED used?

A

1900-1930

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34
Q

tolerance dose AKA

A

threshold dose

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35
Q

tolerance dose was measured in? when?

A

Roentgen
when: 1930s

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36
Q

what does tolerance dose measure?

A

exposure/radiation in air

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37
Q

tolerance dose is established by? for?

A

British X-ray and Radium Protection Committee
For: radiation control

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38
Q

tolerance dose in 1934?
tolerance dose in 1936?

A

0.2 R/day
0.1 R/day

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39
Q

maximum permissible dose is measured in?

A

REM –> radiation equivalent man

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40
Q

Radiation theory in 1930 vs 1950

A

1930: no adverse effects if doses lower than tolerance dose level
1950: no amount of radiation given is completely safe

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41
Q

when was tolerance dose replaced? replaced with what?

A

when: 1950
replacement: maximum permissible dose

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42
Q

what determines REM?

A

1970 dosimetry and risk analysis determined different types of radiation interacted differently with varying organ systems

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43
Q

when was REM replaced? replacement?

A

1980
Sievert (Sv) for REM

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44
Q

Why is SI units used?

A

takes consideration of tissue sensitivity caused by equal absorbed doses of different types of ionizing radiation

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45
Q

types of radiation dose-response relationships

A

threshold
non-threshold

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46
Q

what does radiation dose-response relationships represent?

A

risk of occurrence of malignancies in population that has been exposed to low levels of ionizing radiation

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47
Q

dose-response curves

A

as dose increases so do most effects

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48
Q

threshold relationship

A

below a certain radiation level or dose = no biologic effects observed

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49
Q

non-threshold relationship

A

any radiation dose has the capability of producing a biologic effect = no radiation is considered safe

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50
Q

who regulates radiation protection? importance?

A

federal
Important: improve radiographic quality and reduces patient dose

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51
Q

what is the purpose of the control panel

A

indicates the conditions of exposure and when the tube is energized (visual and audible)

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52
Q

what indicators are on the control panel

A

kVp and mA indicators

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53
Q

what are the radiographic protection features

A

Protective tube housing
control panel
source to image receptor distance indicator
collimation
operator shield

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54
Q

types of radiation monitoring

A

personnel
area monitoring

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55
Q

do we only use SI units for radiation monitoring

A

NO
traditional and SI unit

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56
Q

purpose for radiation monitoring

A

ensures occupational radiation exposure levels kept below annual effective dose limit

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57
Q

what is the annual limit radiation dose

A

50mSv or 5 rem

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58
Q

personal dosimetry

A

monitors radiation exposure of any person occupationally exposed regularly to ionizing radiation

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59
Q

importance of personnel monitoring

A

indicates worker habits
determines occupational exposure over time

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60
Q

types of personal dosimeters

A

optically stimulated luminescence dosimeters (OSL)
film badge
thermoluminescent dosimeters (TLDs)
pocket ionization chambers

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61
Q

what contains aluminum oxide film

A

OSL

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62
Q

how does the filter work in OSL

A

attenuation of different degrees depending on the energy of the photon

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63
Q

Pros of OSL

A

light, easy to carry, not effected by heat/moisture/pressure

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64
Q

film badge composition

A

film holder
filter
film packet

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65
Q

how does filter work in film badges

A

measures energy of radiation –> determines if exposure was from scatter or primary beam

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66
Q

pros of film badge

A

cheap/effective to monitor large numbers of personnel
film = legal doc of radiation exposure
can differentiate types of radiation

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67
Q

what records whole body exposure accumulated at low dose for long periods of time

A

film badge

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68
Q

con of film badge

A

very sensitive = heat and moisture can cause fogging

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69
Q

how does TLDs monitor radiation

A

lithium fluoride crystal

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70
Q

what type of dosimeter best stimulates human tissue

A

TLDs –> crystals

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71
Q

pros of TLDs

A

accurate dose measurement
not effected by humidity, pressure, normal temp

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72
Q

cons of TLDs

A

expensive
single use

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73
Q

how does a pocket ionization chamber function?

A

has ionization chamber measuring radiation exposure

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74
Q

pro of pocket ionization chamber

A

immediate exposure readout (in high exposure areas)
compact/convenient

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75
Q

con of pocket ionization chamber

A

MOST expensive
inaccurate if not read everyday

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76
Q

what is the equivalent dose limit for pregnant women

A

0.5mSv/month

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77
Q

why is lowering equicalent dose limit important for pregnant women?

A

lower total lifetime risk of leukemia/other malignancies

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78
Q

how do survey instruments work?

A

interacts with radiation and ionizes gas (air) in the detector

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79
Q

types of surveying instruments

A

ionization chamber type survey meter (cutie pie)
proportional counter
geiger-muller detector

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80
Q

criteria for surveying instruments

A

portable
sturdy
interact with radiation similar to human tissue
detect all kinds of radiation
affordable

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81
Q

when did radiation damage become apparent

A

early 1896

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82
Q

who were the first to experiment with radiation by self-expose

A

Friedrich Walkoff
Friedrich Giesel

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83
Q

how did the 2 Friedrichs’ conduct their experiment?
conclusion?

A

strapped radium salt to their forearm for 2 hours
Conclusion: radiodermitis

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84
Q

who discovered how to protect against radiation

A

Henri Becquerel

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85
Q

who discovered that radiation effects can leave animals sterile?
how?
when?

A

Albers-Schonberg
xray testes of rabbits and guinea pigs
1903

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86
Q

who discovered that radiation effects can have abnormal egg development?
how?
when?

A

Charles Bardeen
xrays frog larvae spermatozoa = eggs abnormal
1907

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87
Q

when did experimentation occur on bacteria

A

1897 and 1902

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88
Q

when did experimentation occur on seeds

A

1901

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89
Q

what does the law of bergonie and tribondeau state?

A

radiosensitivity of cells is directly proportional to reproductive activity and inversely proportional to degree of differentiation

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90
Q

what did J. Bergonie and L. Tribondeau experiment on? When?

A

radiation effects on testicular germ cells of rabbits
1906

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91
Q

according to the law of bergonie and tribondeau would a stem cell be directly or indirectly proportional?

A

directly proportional to radiosensitivity

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92
Q

Who discovered xray mutations?
how?
when?

A

Hermann Muller
experimented on fruit flies –> radiation induced mutations and mutations are hereditary
1926

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93
Q

how did others replicate Muller’s results? when?

A

experimented on corn and wasps
1928

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94
Q

when did Muller receive his nobel prize

A

1946

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95
Q

who proposed linear non-threshold model?

A

Muller

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96
Q

what did the international commission on radiological protection declare in 1954?

A

irradiation to gonads should be protected as much as possible by collimation or protective screens

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97
Q

what did the international commission on radiological protection declare in 1956?

A

genetic damage assumes greater importance and recommended a max permitted genetic dose

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98
Q

what did the international commission on radiological protection declare in 1982?

A

use gonad shielding while doing gonad procedure
-had 0 point –> had longer exposure time

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99
Q

what did US code of federal regulations state? when?

A

shielding is used to reduce potential hereditary risk
radiation exposure is too low to affect fertility
1976

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100
Q

how is radiation safer today than 1895?

A

tube design and tube housing
xray protection for workers
digital IR and processing

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101
Q

how did xray protection for workers change since 1895

A

shielding for operators and pregnant women
exposure time
distance

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102
Q

how did tube design and tube housing change since 1895

A

filter
collimation
increased SID

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103
Q

what doses has small or nonexistent affect on an embryo or fetus?

A

less than 100mGy

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104
Q

is linear no-thereshold model supported? why?

A

NO
human body can repair faster than that of a fly

105
Q

has there been proven hereditary effects from radiation

A

Not in diagnostic radiation

106
Q

Difference between old and new xray equipment

A

OLD: large doses at longer exposure times
NEW: better image quality for lower doses at shorter exposure times

107
Q

Who studied the differences between old and new xray equipment

A

Gerrit Kemerink

108
Q

AAPM announcement in 2019? why this decision?

A

no more gonad shield for gonad procedures
WHY? difficult to position –> leads to repeats = more radiation

109
Q

Problems with gonadal shielding

A

AEC affected
histogram, LUT, rescaling errors
increase patient radiation dose

110
Q

somatic or non-somatic?
irradiation of genetic material (sperm or egg) is _____?

A

non-somatic

111
Q

stochastic effects

A

probability that effect happens depends on received dose not the severity of the effect

112
Q

deterministic effects

A

both probability and severity are dependent on dose

113
Q

what effect is acute radiation syndrome

A

deterministic somatic effect

114
Q

somatic effect

A

living organism that has been exposed to radiation sustaining biologic damage

115
Q

acute radiation syndrome (ARS) is also known as

A

radiation sickness

116
Q

when does acute radiation syndrome (ARS) occur

A

(humans) after whole body receives large doses of ionizing radiation given over a short period of time

117
Q

example of acute radiation syndrome occurrence

A

Hiroshima bombing
Chernobyl
radiation therapy patients (measured sub-lethal doses)

118
Q

type of radiation in acute radiation syndrome (ARS)

A

particulate radiation

119
Q

4 stages to acute radiation syndrome (ARS)

A

prodromal (initial)
latent
manifest illness
recovery or death

120
Q

3 types of possible syndromes to acute radiation syndromes (ARS)

A

hematopoietic syndrome
gastrointestinal syndrome
cerebrovascular syndrome

121
Q

in radiation therapy how many doses can patient receive with ARS

A

2-3

122
Q

hematopoietic syndrome is also known as

A

bone marrow syndrome

123
Q

when does hematopoietic syndrome occur

A

whole body exposed
threshold dose from 1-10

124
Q

what happens with hematopoietic syndrome

A

RBC, WBC, and platelets decrease = decrease in bone marrow stem cells, lower immune response, lower blood clotting

125
Q

risk factor of hematopoietic syndrome

A

prone to infection and hemorrhage
possible organ failures
bone marrow destruction = death
< 2yr/o death in 6-8 weeks ; >2yr/o die faster

126
Q

is hematopoietic syndrome survival possible?

A

Yes
is exposure not lethal (1-2 doses) bone marrow cells repopulate within 3 weeks to 6 months after irradiation

127
Q

how to enhance survival rate for hematopoietic syndrome

A

intense supportive care
hematologic procedures –> 5+ bone marrow transplants

128
Q

when does gastrointestinal syndrome occur

A

threshold dose 6-10

129
Q

symptoms of gastrointestinal syndrome

A

severe nausea
vomiting
diarrhea up to 24hrs

130
Q

gastrointestinal syndrome
what occurs during latent period

A

symptoms disappear up to 5 days

131
Q

gastrointestinal syndrome
what occurs during manifest illness stage

A

severe nausea
vomiting
diarrhea
signs of high dose rad –> fatigue, fever, anemia etc

132
Q

can death occur with gastrointestinal syndrome? if so why?

A

yes due to damage to cells in gastrointestinal tract (SI) = infection, fluid loss, or electrolyte imbalance

133
Q

can someone survive gastrointestinal syndrome?

A

NO - dies in 3-10 days without support
with support can live a few days longer

134
Q

is gastrointestinal syndrome survival time dependent on dose

A

no

135
Q

higher risk of death
hematopoietic syndrome or gastrointestinal syndrome

A

hematopoietic syndrome –> lower threshold = will die before death by GI syndrome

136
Q

how does cerebrovascular syndrome occur

A

CNS and cardiovascular system received doses of 20-50

137
Q

is cerebrovascular syndrome survivable?

A

no death within hrs to 2 or 3 days after exposure

138
Q

cerebrovascular syndrome
symptoms of prodromal stage

A

excessive nervousness
confusion
severe nausea
vomiting
Diarrhea
loss of vision
burning sensation
loss of consciousness

139
Q

cerebrovascular syndrome
symptoms of latent period

A

12hrs symptoms lessen or disappear

140
Q

cerebrovascular syndrome
symptoms of prodromal SEVERE

A

disorientation
ataxia
cranial swelling
fatigue
seizures
Electrolyte imbalance
meningitis
coma

141
Q

what occurs when the body receives a high radiation dose?

A

destructive response = cell death, enzyme repair, and recovery

142
Q

what determines the organ’s potential for recovery

A

amount of functional damage

143
Q

given repeated exposures what % is irreparable?

A

10%

144
Q

why do we see late somatic effects

A

repeated exposures = irreparable damage

145
Q

why is late effects so dangerous?

A

cellular damage = somatic + hereditary damage
can appear months or years afterwards

146
Q

example of late biological damage

A

cataracts
leukemia
genetic mutations

147
Q

what does epidemiology study (3)

A

incidence, distribution, control of disease in population
ex. who what when why

148
Q

how is the rate of irradiation related malignancies determined

A

compares natural incidence of cancer occurring in population

149
Q

example of radiation can cause cancer

A

Japan bombing = high doses = cancer
helps est. risk for occupational workers

150
Q

what do radiobiologist do?

A

predict risk of malignancies occurring inn low level exposures

151
Q

dose response curves =

A

increase dose = increase effects

152
Q

Recommended by BEIR what curve do we use to predict cancer risk

A

linear non-threshold curve

153
Q

what does the linear non-threshold curve mean?

A

biologic response to ionizing radiation is directly proportional to given dose

154
Q

if absorbed dose is doubled = biologic response ______

A

doubled

155
Q

what does linear-quadratic nonthreshold curve represent

A

estimates risk associated with low level radiation

156
Q

which curve better represents stochastic and genetic effect?

A

linear-quadratic nonthreshold curve

157
Q

which diseases follow linear-quadratic nonthreshold curve

A

leukemia
breast cancer
heritable damage

158
Q

what type of effect appears months or years after exposure?

A

late somatic effect

159
Q

ways to get late somatic effect (3)

A

previous whole or partial body acute exposure (bombing)
previous high radiation doses (therapy)
long term low level doses given over several years (workers)

160
Q

______ does not increase risk of malignancy

A

below 0.1 Sv

161
Q

types of late effects (2)

A

stochastic
deterministic

162
Q

example of stochastic?

A

carcinogenesis
embryologic effect (birth defect)

163
Q

example of deterministic

A

cataractogenesis

164
Q

can cancer always be predicted?

A

no it is random occurrence –> no threshold and no dose to severity relation

165
Q

what are prime factors

A

mAs
kVp
distance

166
Q

other factors to control x-ray emission

A

collimation
filter
generators
size of patient body

167
Q

digital image capture is _____

A

linear

168
Q

pros of digital image capture

A

captures nearly all xray photons
uses computer software

169
Q

what does computer software do in digital image capture

A

subtract density values based on diagnostic values of particular body part

170
Q

window leveling controls? what movement?

A

brightness/darkness screen image
up and down movement

171
Q

window width controls? what movement?

A

ratio of black and white –> contrast
left and right movement

172
Q

what is a technique chart

A

range of techniques set for exam and body part size

173
Q

why do we use technique chart

A

make best quality image at lowest patient dose possible

174
Q

when does a variable change in an exposure system

A

based on thickness of anatomical part

175
Q

pros to fixed kVp systems (6)

A

decreased patient dose
more image info
increased consistency of IR exposure
lengthens exposure latitude
reduced xray tube wear
decreased time settings/patient motion

176
Q

cons of fixed kVp system (2)

A

more scatter
lower contrast

177
Q

pros to variable kVp system (5)

A

allows small changes in kVp adjustments for body part thickness
finer adjustment settings than mAs
higher contrast images
enhanced visibility of fine detail
increased resolution

178
Q

how to establish an exposure system

A
  1. collect exposure data
  2. make single exposure of optimal diagnostic quality on phantom
  3. use variety of technical factor combos both above and below average level keeping mAs the same
  4. measure exposure and density with densitometer
  5. record all clinical fine-tuning in each exposure
179
Q

how to establish fixed kVp system

A
  1. similar to exposure system establishment
  2. keep kVp constant while manipulating mAs to get appropriate image
  3. develop optimal kVp
180
Q

how to achieve best functioning technique factors

A

constant large number of variables with single varying factor

181
Q

how to know when fixed kVp is achieved

A

uniform constrast
easy series of kilovoltages that mAs values can be added to

182
Q

max kVp = ______

A

decreased mAs

183
Q

why would we use max kVp (4)

A

give acceptable density/IR exposure
sufficient penetration = acceptable image contrast
lower contrast
minimizes patient exposure

184
Q

how to establish optimal kVp

A

determine highest kVp and lowest contrast within acceptable limits
does not have to be the best image just highest of acceptable

185
Q

kVp is dependent on _____?

A

body part thickness

186
Q

thicker the body part = ______

A

higher kVp

187
Q

mAs is dependent on _____? (2)

A

body part thickness
IR exposure

188
Q

3 criteria of kVp

A

all contrast is acceptable
small part size = kVp gives adequate penetration
large part size = kVp avoids excessive scatter fog

189
Q

what does an anatomically programmed radiography system do?

A

controls exposure factors based on specific anatomical procedures using AEC and exposure control units

190
Q

what happens if there is no preset available for anatomically programmed radiography systems

A

tech determines ma, kVp, and distance

191
Q

what is ionization chamber used for

A

measures exposure to receptor

192
Q

cons to ionization chambers

A

precise positioning over chamber = possible repeats

193
Q

pros to ionization chambers

A

tech does not need to set exposure time (mAs)

194
Q

where is the ionization chamber located

A

AEC

195
Q

is mA and kVp fixed in AEC

A

no can be manually set

196
Q

how many chambers are in an AEC

A

3 ionization chambers

197
Q

how do ionization chambers work?

A
  1. select combo of chambers –> control exposure
  2. Appropriate voltage reached, exposure terminates by operational amplifier
198
Q

things not to do using an ionization chamber

A

don’t collimate too closely = overexposure
don’t collimate too wide = underexposure

199
Q

how is a back up timer established

A

uses max exposure time to prevent overexposure
based on 150% of anticipated manual exposure time

200
Q

con to back up time

A

if too short = image underexposed

201
Q

what is speed class

A

the speed of any imaging system expresses sensitivity to radiation exposure

202
Q

how do we calculate speed class

A

inherent speed of IR + digital processing speed

203
Q

why is speed class important

A

for image acquisition state

204
Q

given the speed class of 100 what is the average exposure?

A

10uGy

205
Q

what speed class do we typically use? why?

A

200 speed class
WHY: reduces chance of quantum mottle

206
Q

high exposure indicator = ______ exposure

A

over

207
Q

low exposure indicator = _______ exposure

A

under

208
Q

what is target EI

A

ideal amount of IR exposure for specific speed class

209
Q

what does exposure indicator represent

A

Numerical value (preset from manufacturer) that presents IR exposure

210
Q

what needs to be included on DICOM header for every image?

A

deviation index read out

211
Q

errors in histogram analysis can lead to…..?

A

corrupted EI and DI readouts

212
Q

pro of using DI

A

can be used by all manufacturers regardless of their specific methods for EI

213
Q

given DI of > +3.0
Exposure?
Repeat?

A

Overexposed –> 100% too high
no repeat unless saturation occurs

214
Q

given DI of +1 to +3
Exposure?
Repeat?

A

Overexposed –> 25% - 100% too high
no repeat unless saturation occurs

215
Q

given DI of -0.5 to +0.5
Exposure?
Repeat?

A

-20% - +25%
no Target range

216
Q

given DI of -1 to -3
Exposure?
Repeat?

A

underexposed –> 20% - 50% too low
Repeat only if radiologist requests

217
Q

given DI of < -3.0
Exposure?
Repeat?

A

underexposed –> 50% too low
Repeat –> excessive mottle certain

218
Q

how can overexposed images be fixed?

A

windowing

219
Q

what is saturation

A

electrical phenomenon when dexels in a particular area have reached max electrical charge stored –> makes tissues appear black

220
Q

saturation represents?

A

complete loss of data

221
Q

ways to lower or raise DI (4)

A

poor collimation
unusual body habitus
prosthetic devices
gonadal shield

222
Q

Deviation index indicates? number is derived from?

A

INDICATES: IR dose which estimates patient dose
DERIVED: pixel values in histogram

223
Q

how is brightness/density controlled

A

rescaling

224
Q

how is grayscale/contrast controlled

A

LUTs (Gradation)

225
Q

how is sharpness (spatial resolution) controlled?

A

pixel size

226
Q

how is magnification controlled?

A

matrix size or field of view

227
Q

how is shape distortion controlled?

A

part alignment

228
Q

type of monitor to view monitor

A

liquid crystal display (LCD)

229
Q

what is a workstation

A

computer terminals used to adjust image quality and save changes into PACs
for technologist

230
Q

what does PACs stand for

A

picture archiving and communication system

231
Q

what is a diagnostic workstation

A

reading room with 3 monitors
for radiologist

232
Q

component to a light ray

A

double wave –> electrical perpendicular to magnetic component = electromagnetic radiation

233
Q

how does polarizing lens work

A

only parallel waves can pass through polarization filter
perpendicular waves are blocked

234
Q

what happens if 2 polarizing lens are placed perpendicular from each other?

A

all light is blocked out

235
Q

layers to LCD monitor screen (5)

A

polarizing film
flat wires = electricity conduction
nematic liquid crystal material
perpendicular polarizing film
flat wires

236
Q

requirement for imaging monitors

A

fast response
fast refresh time

237
Q

response time

A

time necessary for the monitor to change brightness

238
Q

refresh time

A

time required by entire monitor screen to reconstruct next frame of dynamic moving image or next “slide” in series

239
Q

what does AMLCD stand for

A

Active matrix LCD

240
Q

pros of AMLCD (4)

A

entire rows of pixels can be read out one at a time instead of single pixel
meets requirements for LCD
refresh rate 240Hz
each pixel has their own TFT

241
Q

problems with LCD monitors (3)

A

input lag
dead pixels
dark spots

242
Q

input lag

A

too much processing at once
ex. rescaling, noise reduction, edge enhancement

243
Q

dead pixels

A

appearance of permanent white spots = no electrical charge running through pixel

244
Q

dark spots

A

permanent spots on monitor screen from stuck pixels that are constantly receiving electrical charge

245
Q

when should a monitor be replaced (3)

A

15 defective pixels across entire screen
3 defective pixels in one cm circumference
more than 3 defective pixels adjacent to each other anywhere on the screen

246
Q

pros of LCD monitors (4)

A

no distortion of image or change in sharpness
no glare and reflection of ambient light
no flicker
uniform brightness consistency

247
Q

cons of LCD monitors (5)

A

pixelation
limited contrast = frequent windowing done by radiologist
sensitive to temperature changes = 15 min warm up for full luminance
viewing angle dependence

248
Q

what is viewing angle dependence

A

drop off of brightness depending on viewing angle
must be viewed head on

249
Q

sharpness in recording latent images is determined by?

A

size of dexels

250
Q

sharpness in image processing is determined by?

A

pixel size

251
Q

if spatial resolution is unchanged = ________

A

pixel/dexel size is unchanged

252
Q

what does hardware pixels determine?

A

monitor’s inherent resolution capabilities

253
Q

smaller hardware pixels = _______

A

better sharpness and inherent spatial resolution

254
Q

soft pixel

A

actual displayed light image

255
Q

how to change soft pixel

A

zooming the field of view in or out

256
Q

what is dot pitch known as

A

pixel pitch

257
Q

what is dot pitch

A

distance between centers of any two adjacent hardware pixels

258
Q

pixel size for high resolution

A

0.1-0.2 mm

259
Q

smaller pixel pitch = _______ + ________

A

smaller pixel size
sharper resolution

RAD 354 (1 decks)

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