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x.umn radiology > Biological Effects of Ionizing Radiation (V. 2) > Flashcards

Biological Effects of Ionizing Radiation (V. 2) Flashcards

1
Q

two types of biological effects on a tissue level

A
  • somatic effects

- genetic effects

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2
Q

somatic effects includes all irradiated body cells except _____

A

germ cells of reproductive system

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3
Q

somatic effects are __ and may be….

A

deleterious; may be stochastic or deterministic

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4
Q

genetic effects include…

A

responses of irradiated reproductive cells

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5
Q

genetics effects become primarily important when they are passed on to ______; genetic effects have no consequence on those who….

A

future generations; do not procreate

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6
Q

somatic effects can be…

A
  • acute

- delayed/chronic (latent)

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7
Q

acute somatic effects time and instance

A

within 60 days, usually after a single massive dose

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8
Q

delayed somatic effects time

A

two months (60 days) to as late as 20 years

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9
Q

time lapse between radiation exposure and appearance of effects

A

latent period (usually only used in related to stochastic (malignancy) results)

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10
Q

magnitude of somatic effects depends on…

A
  • individual
  • species
  • cellular/tissue
  • extent of exposure (full v. partial body)
  • total dose
  • dose rate
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11
Q

individual variability refers to that certain individuals in the same species are more _____ than others in response to radiation

A

sensitive or resistant

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12
Q

the expression ______ is frequently used in radiobiology

A

LD50 (30 days)

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13
Q

LD50 means that a certain dose ___________, and the 50% who survive are due to _____

A

kills 50% of exposed animals within 30 days, individual variability

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14
Q

species variability notes…

A

mammals take less Gy than yeast, fruit fly, bacteria…

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15
Q

LD50 refers to…

A

total body exposure

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16
Q

dose rate dependence…radiation dose that would be lethal if given in a short time may result in _______ if given in small increments during a period of years

A

no detectable effects

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17
Q

around ___ of somatic damage is repaired, but irreparable damage is ______

A

4/5, cumulative

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18
Q

when cumulative somatic damage reaches high level, ______ may appear

A

clinical manifestations

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19
Q

3 dose-effect relationship theories

A
  • threshold response
  • linear quadratic response
  • linear reponse
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20
Q

threshold dose theory

A

an increase in radiation dose may not produce an observable effect until tissue has received a minimal level of exposure

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21
Q

in threshold dose theory, once the threshold has been exceeded, increasing the dose will demonstrate exceeding _____

A

tissue damage

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22
Q

examples of threshold dose responses

A

cataract, erythema of skin

23
Q

linear response theory

A

suggests all exposure carries a certain probability of harm and that effects of multiple small doses are additive
“no safe dose”
every dose carries risk

24
Q

linear quadratic response theory

A

implies lesser risk at lower dose rate than linear response or when exposure is fractionated
however, no safe dose

25
Q

____ are more radioresistant probably due to high levels of ____

A

females, estrogen

26
Q

lower metabolic rate and lower stage of nutrition, the ______

A

higher the radioresistance

27
Q

_________ are more efficient in causing biological damage

A

alpha particles

28
Q

radioresistance of many biological tissues increases ___ times when irradiation is conducted with reduced oxygen

A

2-3

29
Q

dose required to produce deterministic effects

A

1-2 Gy

30
Q

with chronic deterministic effects, there is usually a __________

A

threshold dose below which the effects are not manifested

31
Q

with chronic deterministic effects, with increasing dose the severity of defect ____

A

increases

32
Q

skin deterministic effects

A

1.65-3.5 Gy = erythema

higher doses = dermatitis

33
Q

hair determinstic effects

A
  1. 0-6.0 Gy = epilation (loss of hair)

- ^^latent period of 3 weeks

34
Q

sterility deterministic effects (exposure to gonads)

A 
males = 4.0 Gy
females = 6.5 Gy
35
Q

when was x-ray discovered?

A

November 1895

36
Q

first case of radiation-induced human injury

A

1896

37
Q

first case of x-ray induced cancer reported

A

1902

38
Q

cataract deterministic effect

A
  1. 0-5.0 Gy for single exposure

10. 0 Gy for exposures over a period of month/years

39
Q

standard therapeutic radiation dose for treating cancer = _____ administered over a period of ______ at a rate of ____ Gy ____

A

50-60 Gy, 10-14 weeks at a rate of 2.5 Gy twice weekly

40
Q

adult teeth are ______ to direct effects of radiation; no effect on _______

A

very resistant, enamel/dentin/cementum

41
Q

radiation effect/caries type in which individuals whose salivary glands do not function d/t radiation (xerostomia)

A

radiation caries

42
Q

radiation caries occur at the ____

A

CEJ

43
Q

radiation on developing teeth characteristics….

A

less than 10 Gy has very little/no visible effect

44
Q

radiation to infant and their developing dentition may include…

A
  • destruction of tooth bud
  • tooth malformation
  • delay in eruption
45
Q

small teeth/small roots in response to radiation can be termed…

A

radiation stunting of teeth

46
Q

most serious complication of radiation effects on oral tissue

A

jaw osteoradionecrosis

47
Q

jaw osteoradionecrosis is primarily due to damage to the _____ of the jaw and the consequent __________

A

blood vessels, decreased capacity of the bone to resist infection

48
Q

jaw osteoradionecrosis is more common in ____

A

Mandible than the Mx

49
Q

with jaw osteoradionecrosis, ________ makes possibility of bone infection/necrosis becomes very high

A

tooth extraction/other injury

50
Q

at 3rd or 4th week of radiation therapy, oral mucosa becomes ______(___). As therapy continues, mucosa forms ______.

A

red and inflamed (mucositis), yellow pseudomembrane

51
Q

when is mucositis d/t radiation therapy most severe?

A

at end of treatment period

52
Q

with mucositis d/t radiation therapy, secondary infections by _____ is a common complication

A

candida albicans

53
Q

with mucositis d/t radiation therapy, healing begins soon after ____ and is usually complete in about _____ after therapy

A

treatment, two months

54
Q

taste acuity is _________ into radiation therapy; complete recovery of taste usually occurs in ________ following treatment completion

A

reduced or lost about 4 weeks; 2 to 4 months

x.umn radiology (15 decks)

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