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radiation biology Flashcards

1
Q

why are patients afriad of radiation

A

found all over in the news, from reputable sources

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2
Q

Ionizing radiation leads to what

A

Formation of free radicals

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3
Q

what types of effect can free radicals have

A 
Direct effects (33%)
Indirect effects (67%)
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4
Q

what are the direct effects of free radicals

A

Free radical action directly on biological moleucles

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5
Q

what are the indirect effects of free radicals

A

Radiolysis of water which then affects biological mocules

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6
Q

What are the possible outcomes of ionizing radiation on Cell DNA

A

Cell Death
Heritable mutation
Carcinogenesis

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7
Q

what dose is needed for Deterministic effects

A

Clinical symptoms appear at any dose above the threshold dose

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8
Q

what defines severity for deterministic effects

A

Proportional to dose

caused by high radiation

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9
Q

what does Deterministic effects leads to

A

Increased cell death

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10
Q

what dose is needed for stochastic effects

A

No threshold, an all or none response

greater dose increases probablitiy though

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11
Q

what does Stochastic effects lead to

A

Cell DNA injury

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12
Q

what is the Law of Bergonie and Tribondeau

A

Radiosensitivity is different for different tissues

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13
Q

what defines the radiosensitivity of different tissues

A

Amount of undifferentiated cells (undifferentiated more susseptible)
Mitotic activity (greater activity greater risk(
Length of active proliferation(greater is more likely)
also OOcytes and Lymphocytes very susseptible

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14
Q

what non tissue based factors for radiation injury

A

Age(young more susseptible)

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15
Q

what organs have high radiosensitivty

A 
Lymphoid ttisues/organs
Bone marrow
Testes
Ovaries
Small intestine
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16
Q

What organs have fairly high radiosensitivity

A 
Skin 
Cornea and lens of eyes
Esophagus
Stomach
Rectum
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17
Q

what organs have moderate radiosensitivity

A

growing cartilage
Growing bone
Vasculature

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18
Q

what organas have fairly low radiosensitivity

A 
Mature cartilage
Mature bone
Lungs
Kidney
 liver
Pancrease
Adrenal gland
Pituitary gland
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19
Q

what organs have low radiosensitivy

A

Muscle
Brain
Spinal cord

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20
Q

what are the modifying factors in radiation injury

A 
Radiation source (medical and background)
Dose distribution (whole body vs local)
Dose rate (high rates worse)
linear energy transfer (LET)
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21
Q

what is linear energy transfer

A

The rate at which the energy from photons is imparted as they travel through matter

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22
Q

The measure of the total energy transferred from any type of radiation to matter

A

Absorbed dose (rad or Gy)

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23
Q

what is 1 Gy

A

1 Gy=100 rad

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24
Q

A measure of how different types of radiation affect various tissues

A

Equivalent dose (Sv=Gy)

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25
Q

Calculating equivalent dose

A

equivalent dose= radiation weighting factor x absorbed dose

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26
Q

A measure of the estimate risk in hmans

A

Effective dose

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27
Q

calculating effective dose

A

sum of tissue weighting factor x equivalent dose

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28
Q

Weighting factor for Effective and Equivalent

A

Effect: tissue
Equivalent: radiation

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29
Q

what causes acute radiation syndrome

A

Whole body irradiation

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30
Q

onset of acute radiation syndome

A

Onset is more rapid and severe with greater dose

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31
Q

Managing accute raditation syndome

A

depends on stage

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32
Q

Stage of acute radiation syndrom depends on

A

The level of dose

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33
Q

dose and symtoms of prodromal acute radiation syndrom

A 
1.5 grays
Anorexia
Nausea
Comiting
Diarrhea
weakness
fatigue
34
Q

dose of latent acute radiation syndrom

A

2 gray

35
Q

dose and symptoms of Hematpoietic acute radation syndrome

A

2-7 gray
Infections (immunosuppression
Hemorrhage (decreased clotting)
Anemia

36
Q

Dose and symptoms of Gastrointestinal acute radiation syndrom

A 
7-15 gray
Dehydration
Diarrhea
weight loo
Septicemia
37
Q

dose and symptoms of acute radation syndome for Cadiovascular and CNS

A 
50 gray
Hypotension
Cardiac muscle necrosis
Stupor
Incoordination
Disorientation
Convulsions
38
Q

High radiation dose effects can be

A

Cataracts in eyes
Shortened life expectange (2 months to 2.6 years)
Impaired growth in children

39
Q

what causes shortened life of high radiation dose patients

A

Increased heart disease
Stroke
Non-cancerous disease of digestive, respiratory, and hematopoietic systems

40
Q

what does it take for radition to affect children in utero

A

.1 grays

41
Q

what are some abnormalities in children boen after radiation exposure in utero

A 
Microcephaly
Microphthalmia
Cataracts
Mental impairment
Small birth size and reduced growth throughout life
Genital and skeletal malformations
42
Q

how to differentiate radiation cancer from other cancers

A

Indistinguishable

43
Q

how do we study radiation induced carcinogenesis

A

Japanese atomic bomb survivors

44
Q

why did people die in two months in 1945

A

Burn injuries and acute radiation system

45
Q

how was the study conducted to look at radiation

A

Systematic studies on suriviors and offspring (120,000 people) to see that they got leukemia, esophageal, salivary gland, and thyroid gland tumors

46
Q

do the unexposed offspring of atomic bomb surviors have mutations

A

no (also true for the children of parents who have had radiotherapy)

47
Q

what is the linear nonthreashold (LNT) hypothesis

A

Increased risk for carcinogenesis above 100,000 microGy

exposures are addative

48
Q

when doing dental X-rays what are also are exposed

A 
Red Bone Marrow
Esophagus
Thyroid
Bone
Brain
Salivary glands
Skin
Lymph nodes
muscle
Oral mucosa
49
Q

what is the most common oral cancers from radiotherapy

A

Squamous cell carcinoma (2-3%) - Tongue, floor of mouth, gingiva, lip, palate

50
Q

what type of radiotherapy is found in the oral cavity

A

fractionated radiotherapy reaching 60-70 Gy

51
Q

what can oral radiotherpay be combined with

A

Surgical intervention and/or chemo

52
Q

when is mucositis found

A

2nd wek of therapy

53
Q

what does Mucositis lead to

A

Erythematous mucosa( sloughing of irradiated tissue ans a white yellow pseudomembrane)

54
Q

problems with Mucositis

A

Painful
Secondary infection
Difficulty consuming food

55
Q

healing of mucositis

A

Heals within 2 months after leading to atrophic, thin, avascular tissues

56
Q

why does Xerostomia occure

A

Parenchymal cells of salivary glands are radiosensitive leading to reduced salivary flow

57
Q

what does Xerostomia lead to

A

Reduced buffering potential
decalcifaction of enamel
Pain/tenderness
Difficulty chewing and swolling

58
Q

when does XXerostomia heal

A

6-12 months

59
Q

how does Xerostomia heal

A

heals, but persistent reduced flow occures after 1 year

60
Q

when does taste loss cure

A

Second/third week of therapy

61
Q

how much does taste loss occure

A

Acuity decreased by a factor of 1000 to 10000

62
Q

what may also lead to taste loss

A

Reduced salivary flow

63
Q

Healing taste loss

A

Recovery in 60-120 days

64
Q

what is trismus

A

Inflammation and fibrosis of musculature, usually the medial and lateral pterygoid muscles and masseter muscles

65
Q

when do you get trismus

A

limited opening 2 months after completion of radiation therapy

66
Q

how does one fix trismus

A

Physical therapy

67
Q

why does radiation caries lead to rempant caries

A

due to salivary changes and direct effect on teeth

68
Q

how does radiation effect on salivary gland change shit to lead to caries

A 
Reduced saliva flow
Decreased saliva pH
Reduced saliva buffering
increased salivary viscosity
Altered bacterial flora
debris accumlation
69
Q

how does radiation directly effect teeth

A

Flake enamel

70
Q

How to fix radiation caries

A

Good oral hygeine
Daily fluoride varnish
Restricted cariogenic foods
Restorations

71
Q

what happens to children receiving radiotherapy

A

Incomplete formed teeth (root)
Malformed teeth
Tooth bud destrcution
Microdontia

72
Q

how to fix impeded tooth development in kids

A

Resotorative pocedures

73
Q

how much radiation does it take for Osteoradionecrosis

A

50-60 Gy

74
Q

what does Osteoradionecrosis lead to

A

Reduction of blood supply, bone remodeling capacity (brittle), and mineralization
breakdown of mucosa with bone exposure

75
Q

what part of the mouth is most exposed to osteoradionecrosis and why

A

Mandible less vasculature

76
Q

what is done to fix osteoradionecrosis

A

Debridement
Resection
restoration

77
Q

what is done to minimize the effects of osteoradionecrosis

A

Pre-radiotherapy clearance when possible

78
Q

what are most mutations from radiation

A

Deletorous

79
Q

what gender is more radioselective

A

Males

80
Q

ways to reduce the effect of radiation

A

Low dose

Low dose rate

radiology (10 decks)

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