Brainscape's Knowledge GenomeTM

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


See full index

Radiology > Radiation Biology > Flashcards

Radiation Biology Flashcards

1
Q

Why do we need to understand radiation biology?

A
  • health risk involved with ionizing radiation
  • educate the public
  • to get licensed as a dentist
  • protect the public
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do you measure radiation?

A
  1. Exposure Dose; R vs. Coulombs/kg
  2. Absorbed Dose; RAD vs. Gray (G)
  3. Equivalent Dose; REM vs. Sievert (Sv)
  4. Effective Dose; REM vs Sievert (Sv)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is exposure dose measured in?

A
  • R (roentgen); standard
  • air kerma or Coulombs/kg
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is absorbed dose measured in?

A
  • RAD (radiation absorbed dose); standard
  • Gray (Gy)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is equivalent dose measured in?

A
  • REM (Roentgen Equivalent in Man); standard
  • Sievert (Sv)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is effective dose measured in?

A
  • REM (Roentgen Equivalent in Man); standard
  • Sievert (Sv)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is exposure dose?

A

a measure of the capacity of radiation to ionize air

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

What is absorbed dose?

A

energy absorbed by tissue

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

What is equivalent dose?

A

modified by radiation weighting factor

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

What is effective dose?

A

modified by tissue weight factor

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

What is 1 RAD (radiation absorbed dose)?

A

100 ergs or radiation energy in 1 gram of absorbed material

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

In x-radiation what two types of dose are equal?

A

equivalent dose
absorbed dose

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

What is the equivalent dose used for?

A

To compare the biological effects of different types of radiation

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

How are absorbed dose and equivalent dose related?

A

equivalent dose is the absorbed dose times the radiation weighing factor

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

What does the radiation weighing factor (WR) depend on?

A

depends on the type and energy of the radiation involved

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

How many REM are in a Sv?

A

100 rem = 1.0 Sv

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

How many RAD are in a Gy?

A

100 RAD = 1.0 Gy

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

What is the equation for effective dose?

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

What is the definition of effective dose?

A

This measure is used to specifically calculate risks of radiation to human tissues on a common scale

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

What is the calculation for effective dose?

A

The calculation is a product of the sum of dose equivalence to the specific tissues or organs exposed and the biological tissue weighting factor

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

The value of effective dose is an estimated measure of…

A

all somatic and genetic radiation-induced risk even if the entire body is not uniformly exposed

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

What is effective dose used for

A

Used to assess risk of non-uniform radiation to localized part of body and degree to which this would increase a person’s “whole body” risk of
1. cancer induction and/or
2. induction of genetic mutations

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

What can happen when you expose an object to radiation?

A
  • no interaction = 9%
  • coherent scattering = 7%
  • photoelectric absorption = 27%
  • compton scattering = 57%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is coherent scattering?

A

radiation excites the atoms of the biological structure but does not ionize it

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

What are the two ionizing interactions with objects?

A
  • compton (incoherent) scatter
  • photoelectric effect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What type of interaction is this?

A

Comptom (incoherent) scatter

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

What type of interaction is this?

A

photoelectric effect

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

What kind of injuries can occur from x-ray interactions with matter?

A
  • biochemical lesions that have…
  • deterministic effects like lethal DNA damage, cell death, decreased tissue/organ function
  • stochastic effects like sub-lethal DNA damage, gene mutation, replication of mutated cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are examples of deterministic and stochastic effect from x-radiation injury?

A
  • deterministic (xerostomia, cataracts, osteoradionecrosis)
  • stochastic (leukemia, thyroid cancer, salivary gland tumors, heritable disorders)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Ionization from ionizing radiation
exposure sets off multiple direct
and indirect _________ reactions in < 1 sec

A

molecular

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

Enzymatic repair or further deleterious molecular changes occur in _____________ after x-radiation exposure

A

minutes to hours

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

Deterministic and stochastic effects of x-radiation exposure take place over time from…

A

months, to decades, to
generations

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

What happens to x-rays when there is no interaction with the object?

A

X-ray photon enters object (eg. patient or other biologic tissues) and exits with no change in its energy

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

What happens when x-rays have a photelectric interaction with an object?

A
  • X-ray photon collides with an orbital electron and loses its energy
  • Ejected photoelectron loses it energy
  • Results in an atom with an altered electric state, i.e., “+” charge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What percent of all interactions of x-rays are photoelectric interactions?

A

27-30%

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

If the degree of photoelectric effect
is significant, this may affect…

A

biologic structure, function or both

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

Effects of the photoelectric interaction on biological tissues are…

A

often deleterious biologic changes; e.g. altered metabolic function, malignancy, etc

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

What percent of x-ray interactions with objects are compton interaction/scatter?

A

57-62%

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

What is a compton interaction/scatter?

A
  • X-ray photon collides with an outer
    orbital electron losing some energy
  • X-ray photon continues in different direction with less energy creating more scatter until all the energy is lost
  • results in an atom with an altered
    electric state, i.e., “+” charge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What happens during a coherent interaction between x-rays and an object?

A

X-ray photon of low energy interacts with an outer orbital electron and changes direction

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

What are the similarities between direct and indirect x-ray injuries?

A

– Both effects occur quickly
– Both effects take hours to decades to become evident
– Both are a result of ionization

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

What does direct biologic injury from x-rays do?

A

➢ Directly ionizes biologic maromolecules
➢ Contributes to about 1/3 of biologic effects

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

What does indirect biologic injury from x-rays do?

A

➢ X-ray photons absorbed by H2O → free radicals → biologic damages
➢ Contributes to about 2/3 of biologic effects

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

What are the three paths that cells can take after direct effect injury?

A
  • repair (cell survival)
  • misrepair (carcinogenesis/mutation)
  • unrepaired (death)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the primary method of cell damage from the indirect effect?

A

radiolysis of water caused by x-radiation resulting in free radicals

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

What are free radicals?

A

a free atom or molecule carrying an unpaired orbital electron in the outer shell

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

Free radicals seek a more stable
configuration which results in formation of…

A

toxic substances
- hydrogen peroxide
- H+
- water

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

What does the threshold non-linear curve of radiation show?

A
  • Small exposures do a substance do not produce measurable changes
  • A threshold must be reached before changes are observed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Most biologic effects are linear or non-linear curves?

A

non-linear

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

What does the linear non-threshold curve of radiation show?

A
  • Dose is proportional to the response
  • No matter how small the dose, there is some damage or risk
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What does the non-linear nonthreshold curve of radiation show?

A
  • No threshold
  • Minimal damage at first with increased rate of damage with increased dose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What does determinitic risk/effect mean for radiation?

A

severity is proportional to the dose
- higher does can lead to…
●Erythema
●xerostomia
●cataract
●osteoradionecrosis
●fertility issues
●fetal development
●alopecia

53
Q

What does stochastic effect mean for radiation?

A
  • Have no dose threshold
  • Probability of occurrence is proportional to dose
  • Severity of effects does not depend on dose
  1. To somatic cells -genetic mutations cause malignancy
  2. To germ cells - genetic mutations cause heritable effects
54
Q

What type of curve do deterministic effects follow?

A

threshold - sigmoid

55
Q

What type of curve do stochastic effects follow?

A

linear - no threshold
linear - quadratic

56
Q

What is the difference between a genetic versus somatic radiation injury?

A

Genetic Injury
– no affect on parent
– affects future generation

Somatic Injury
– affects parent
– no affect on future generation

57
Q

What is the sequence of radiation injury

A
  • Latent period
  • Period of injury
  • Recovery period
58
Q

What is the latent period of radiation injury?

A
  • Time that elapses between exposure and appearance of clinical signs
  • May be short or long depending on:
    – Total dose
    – Dose rate
59
Q

Shorter latent period of radiation injury if…

A

– Increased amount of radiation
– Faster dose rate

60
Q

What happens during the period of injury of radiation injury?

A
  • Cell death
  • Changes in cell function
  • Breaking or clumping of chromosomes
  • Giant cell formation
  • Cessation of mitotic activity
  • Abnormal mitotic activity
61
Q

What happens during the recovery period of radiation injury?

A
  • full recovery for a large percentage of individuals from a few weeks up to two years after exposure
  • No recovery i.e, death liley at higher does of >1.2 Gy (120 Rads).
62
Q

What are the factors modifying effects of x-radiation?

A
  1. Total dose
  2. Dose rate
  3. Oxygen
  4. Area exposed
  5. Cell type and function
  6. Age
63
Q

As the total dose increases what happens to damage?

A

more damage

64
Q

As the dose rate increases what happens to cellular repairs and damage?

A

decreased cellular repairs
more damage

65
Q

As the oxygen content increases what happens to radiosensitivity and damage?

A

increased radiosensitivity
more damage

66
Q

What is the difference between radiosensitive and radioresistant?

A

Radiosensitive – young, immature, rapidly growing and dividing, least specialized

Radioresistant – mature, specialized cells

67
Q

What types of animals are more radiosensitive?

A

Mammals more sensitive than reptiles, insects, bacteria

68
Q

What types of cells have an increase radiosensitivity?

A
  • increased mitotic activity
  • inceased cell metabolism
  • immature cells/not highly specialized
69
Q

What age are people more at risk for radiation injury?

A

Pediatric Patients

70
Q

Why are pediatric patients more at risk for radiation injury?

A
  • Rate of cellular and organ growth puts tissues at greatest level of radiosensitivity
  • Greater life expectancy puts children at 2-10 greater risk of being afflicted with a radiation induced cancer
71
Q

What is acute radiation syndrome?

A

A collection of signs and symptoms following acute whole-body radiation exposure

72
Q

How do we know what actue radiation syndrome is?

A

Information derived from animal experiments, patient therapeutic radiation exposures, atomic bombings and radiation accidents.

73
Q

What is a sub-lethal exposure of radiation?

A

< 2 Gy (200 Rads)

74
Q

What is a lethal exposure of radiation?

A

2 – 8 Gys (200 to 800 Rads)

75
Q

What is a supralethal exposure to radiation?

A

> 8 Gys (800 Rads)

76
Q

If you have a higher dose or radiation what happens to the latent period and onset of severe symptoms?

A

shorter latent period and rapid onset of severe symptoms

77
Q

What are the different categories of acute radiation syndrome?

A
  1. Prodromal period
  2. Hematopoietic syndrome
  3. Gastrointestinal syndrome
  4. Central nervous system and cardiovascular syndrome (CNS/CVS syndrome)
78
Q

How much radiation is the prodromal period?

A

(<200 R; <2Gy)

79
Q

How much radiation is the hematopoietic syndrome?

A

(200- 1,000R; 2-10 Gy)

80
Q

How much radiation is the gastrointestinal syndrome?

A

(1,000 – 10,000R; 10 – 100 Gy)

81
Q

How much radiation is the Central nervous system and cardiovascular syndrome?

A

(>10,000R; >100 Gy)

82
Q

When does the prodormal syndrome occur?

A

Shortly after exposure to whole-body radiation

83
Q

What are the symptoms of prodormal syndrome?

A
  • nausea
  • vomiting
  • diarrhea
  • anorexia
  • general malaise
  • fatigue
  • drowsiness
  • listlessness
84
Q

How quickly do symptoms of prodormal syndrome resolve?

A

Symptoms resolve after several weeks

85
Q

What is the hemopoietic syndrome?

A

irreversible injury to the proliferative capacity of the spleen and bone marrow with loss of circulating peripheral blood cells

86
Q

What are the symptoms of hemopoietic syndrome?

A
  • infection from the lymphopenia and granulocytopenia
  • hemorrhage from thrombocytopenia
  • anemia from the erythrocytopenia
87
Q

How soon does death occur with hemopoietic syndrome?

A

10-30 days

88
Q

What is the gastrointestinal syndrome?

A
  • extensive damage to the GI system (in addition to the hemopoietic system)
  • There is extensive injury to the rapidly proliferating basal epithelial cells of the intestinal villi which leads to atrophy and ulceration.
89
Q

What are the symptoms of gastrointestinal syndrome?

A
  • loss of plasma and electrolytes
  • hemorrhage and ulceration
  • diarrhea, dehydration, weight loss
  • Infection
90
Q

How soon does death occur with gastrointestinal syndrome?

A

3-5 days

91
Q

What is cardiovascular and CNS syndrome?

A
  • radiation induced damage to neurons and fine vasculature of brain
  • Intermittent stupor, incoordination, disorientation, and convulsions from extensive CNS damage
92
Q

How soon does death occur with cardiovascular and CNS syndrome?

A

death in a few minutes to 48 hours

93
Q

Oral tissues are subjected to high doses of radiation during the treatment of…

A

malignant tumors of the soft palate, tonsils, floor of the mouth, nasopharynx, and hypopharynx

94
Q

Total radiation doses to treat malignant tumors ranges from…

A

6,000 - 8,000 Rads Or 60 -80 Gy

95
Q

What is the radiation dose for a solid tumor?

A

60 – 80 Gy

96
Q

What is the radiation dose for lymphomas?

A

20 – 40 Gy

97
Q

What is the radiation dose for intraoral cancer?

A

50 Gy

98
Q

What is the radiation dose for a Full Mouth series?

A

35 µSv

99
Q

How many µSv are in 1 Gy?

A

1 Gy = 1 million µSv

100
Q

What is the radiation dose for a single intraoral?

A

1.3 µSv

101
Q

What is the radiation dose for a panoramic radiograph?

A

9 µSv

102
Q

What provides greater tumor destruction: a single large dose or multiple small doses?

A

Fractionation of the total dose into multiple small doses provides greater tumor destruction

103
Q

Fractionation of radiation for cancer treatment also increases cellular _________ of the normal tissues

A

repair

104
Q

What are the radiation effects on the mucosa?

A
  • mucositis
  • secondary infections
105
Q

What are the radiation effects on the taste buds?

A
  • loss of taste
106
Q

What are the radiation effects on the salivary glands?

A
  • xerostomia
107
Q

What are the radiation effects on the teeth?

A
  • lack of or retarded development
  • radiation caries
108
Q

What are the radiation effects on the bone?

A

osteoradionecrosis

109
Q

What are the radiation effects on the muscle?

A

fibrosis

110
Q

Epithelial atrophy, xerostomia and mucositis all result in _____________ by the 2nd or 3rd week of treatment

A

loss of taste

111
Q

Recovery of taste sensitivity will occur in ____ months following treatment

A

2 - 4

112
Q

Adult teeth are or are not resistant to the direct effects of radiation exposure

A

very resistant!

112
Q

T/F: there is no discernible effect on the crystalline structure of enamel, dentin, or cementum with radiation

A

True

113
Q

Radiation does or does not increase the solubility of teeth?

A

Does not

114
Q

When teeth are irradiated during the developmental stage, their growth may be severely __________

A

retarded

115
Q

If the radiation precedes calcification, the tooth bud may be ___________

A

destroyed

116
Q

Irradiation ______ initiation of calcification, teeth may demonstrate malformations and arresting general growth

A

after

117
Q

Generally, if some portion of the salivary gland has been spared, the dryness of the mouth subsides in…

A

6 month to 1 year

118
Q

_____ salivary glands are often exposed unavoidably to radiation during treatment for carcinoma of the oral cavity or oropharynx

A

Major

119
Q

Parenchymal cells (especially of the parotid glands) are very sensitive to X-rays and are replaced by…

A

fibrosis and adiposis with parenchymal degeneration and loss of fine vasculature

120
Q

The residual saliva after radiation has a _______ pH, which is acidic enough to initiate decalcification of enamel

A

lowered (from 6.5 to 5.5)

121
Q

The buffering capacity of saliva after radiation is reduced _____%

A

40 - 45%

122
Q

Children may show defects in the permanent dentition, such as…

A
  • retarded root development
  • dwarfed teeth
  • failure to form one or more teeth
123
Q

A dose as low as 200 R at the age of 5 months has been reported to cause __________ of the enamel

A

hypoplasia

124
Q

Irradiated teeth with altered root formation will or will not erupt?

A

will erupt
- eruptive mechanism is much more radiation resistant

125
Q

A rampant form of decay that may affect individuals who received a course of radiation therapy that include exposure of the ___________

A

salivary glands

126
Q

The primary damage to bone is from irradiation to the…

A

– fine vasculature
– marrow (affecting vascular and hemopoietic elements)

127
Q

What does inflammation and fibrosis of muscle from radiation cause?

A

contracture and trismus in the muscles

Radiology (35 decks)

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