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Radio 1 > Rad Bio > Flashcards

Rad Bio Flashcards

1
Q

x-rays, gamma rays are what kind of radiation (charged/particulate)?
neutron?
alpha/beta/proton?

A

uncharged, non-particulate

uncharged, particulate

charged, particulate

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2
Q

Five radiation characteristics that effects ionization in living tissues

A
  1. charge (Q)
  2. energy (E)
  3. mass (M)
  4. velocity (V)
  5. linear energy transfer (LET)
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3
Q

Greater charge effect on tissue?

A

Greater ionization

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4
Q

Greater Energy effect on tissue?

A

greater cell death, greater ionization

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5
Q

Mass of ionizing particle effect on tissue?

A

Lighter - sparse ionization, follow indirect path

Heavy - Densely ionizing, direct path

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6
Q

Velocity of ionizing particle effect on tissue

A

Increase velocity = decrease ionizations

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7
Q

Why does increasing velocity of a particle decrease ionization?

A

slower particle has greater chance of coming close to orbital electron

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8
Q

Linear energy transfer (LET) definition?

A

avg energy released on ionization per length (keV/um)

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9
Q

High LET particles? Low?

A

High: alpha, proton, neutron

Low: x-rays, y-rays

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10
Q

LET vs charge? velocity?

A

LET directly proportional to square of charge

LET inversely proportional to square of velocity

LET proportional to Q^2/v^2

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11
Q

Primary target for cell damage from ionizing rad?

A

DNA

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12
Q

Double strand DNA break leads to (3)

A

Cell death
genetic mutations
carcinogenesis

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13
Q

Direct effect of ionizing damage? How much biological damage caused this way?

A

Direct ionization of macromolecule (DNA); 1/3rd

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14
Q

Indirect effect of ionization damage? How much bio dmg caused this way?

A
  1. ionize water to free radical OH and H (and an aqueous electron)
  2. free radical interacts with DNA

2/3

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15
Q

How fast does damage happen from these mechanisms?

A

10e-5 seconds

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16
Q

Relation between LET and effect type? Low vs High LET?

A

Low LET - mostly indirect effect

High LET - mostly direct effect

17
Q

What is deterministic effect of radiation injury caused by?

Is there a threshold dose?

Severity of effects vs dose?

Probability of having effects?

A

killing large # cells

YES

Proportional to dose

Will definitely happen

18
Q

What is stochastic effect of radiation injury caused by?

Is there a threshold dose?

Severity of effects vs dose?

Probability of having effects?

A

sublethal damage leading to carcinogenesis or heritable mutation

NO, happens at random

Independent of dose

Greater dose = greater chance

19
Q

Host factors influencing how much damage radiation causes? (7)

A 
Volume of tissue
Radiosensitivity of cells/tissue
Stage in cell cycle
Reproductive capability
Age
Oxygen
Temp
20
Q

O2 and Temp vs damage

A

more O2 and higher temp = more damage

21
Q

Stage in cell cycle with most/least damage?

A

M - most

S - least

22
Q

Most radiosensitive cells are (3)

A

undifferentiated, rapidly dividing, many future divisions

23
Q

Most sensitive tissue

Least sensitive tissue

A

Most: bone marrow, intestines, oral mucous membrane, spermatogenic cells

Least: Muscle, brain/spinal chord, erythrocytes (RBCs)

24
Q

Exceptions to law of Bergonie and Tribondeau

A

oocytes and small lymphocytes are mature yet still sensitive

25
Q

Deterministic effects on fetus (4)

A

Teratogenic effects

  1. intrauterine death in 1st week
  2. intra-auterine growth retardation
  3. congenital malformations
  4. developmental abnormalities
26
Q

Stochastic effects on fetus

A

childhood cancer

27
Q

Radiogenic effects in stages of gestation:
Preimplantation?
Organogenesis?
Fetal?

A

Preimplantation: all or none
Organogenesis: congenital abnormalities, growth retardation
Fetal: growth retardation, microcephaly, mental retardation

28
Q

Fetal dose from dental xray vs dose threshold for birth defects?

A

Dental xray:

29
Q

Why do we hold back on dental x-rays then?

A

to reduce risk of stochastic effects

30
Q

Acute radiation syndromes chart

A

yeah the chart

31
Q

4 Possible therapies for hematopoietic syndrome?

A

Blood transfusion
Bone marrow transplant
Abx
Isolated environment

32
Q

oral radiotherapy dose and duration

A

64-70 Gy in 6-7 weeks

33
Q

Radiation effect on oral mucosa?

A

Desquamation
Inflammation/pain
white/yellow pseudomembrane
secondary fungal infection

34
Q

Long term radio effects on oral mucosa? Heals when?

A

atrophic thin avascular mucosa

heals after 2 mo

35
Q

Radiation effect on taste buds? Heals?

A

lower taste acuity, heals 2-4 mo

36
Q

Radiation effect on teeth:
prior to calcification?
post-calcification?
Erupted teeth?

A

pre-calcification: tooth bud destroyed
post-calcification: malformations and arrested growth
erupted: radioresistant

37
Q

Radiation effect on salivary glands?

A

reduced secretion/xerostomia

pH altered –> decalcification and radiation caries

38
Q

radiation effects on bone

A

damage to vasculature of periosteum and cortical bone

kills osteoblasts :(

Radio 1 (6 decks)

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