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x.umn radiology > Biological Effects of Ionizing Radiation (V. 1) > Flashcards

Biological Effects of Ionizing Radiation (V. 1) Flashcards

1
Q

dose to air, as radiation comes out of x-ray tube

A

exposure, air kerma

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2
Q

dose to tissues, as radiation enters body of patient

A

absorbed dose, equivalent dose, effective dose

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3
Q

a measure of the ionization produced in the air by x-rays or gamma rays

A

exposure

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4
Q

traditional unit of exposure; SI unit

A

roentgen (R); air kerma (Gy or Gray)

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5
Q

what does “kerma” stand for?

A

kinetic energy released in matter

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6
Q

air kerma measures _______ transferred from ____ to _____ of the absorber

A

kinetic energy, photons, electrons

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7
Q

kerma values in the is called….

A

air kerma

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8
Q

absorbed dose is energy transferred from ionizing radiation per ________ of _____

A

unit mass, irradiated material

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9
Q

traditional unit of absorbed dose; SI unit

A

rad (radiation absorbed dose); Gray (Gy)

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10
Q

absorbed dose varies with __________ and __________

A

type/energy of radiation, type of absorbing material

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11
Q

equivalent dose is used to compare the ______ of different types of radiation on a _______

A

biologic effects, tissue/organ

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12
Q

equivalent dose depends on ____

A

LET

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13
Q

high LET radiation causes (more/less) harm than low LET radiation

A

more

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14
Q

tradition unit for equivalent dose; SI unit

A

rem (roentgen equivalent man); Sievert (Sv)

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15
Q

1 Sv = __ Gy

A

1 Gy

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16
Q

effective dose is used to estimate risk of ______

A

radiation in humans

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17
Q

true/false? not all tissues respond identically to radiation

A

true

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18
Q

effective dose is the ________ of the _________ of a tissue and ________ applicable to each of the tissue irradiated

A

sum of the products, equivalent dose, weighting factors

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19
Q

unit of effective dose

A

Sv

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20
Q

a measurement of decay or disintegration of a sample radioactive material

A

radioactivity

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21
Q

traditional unit of radioactivity; SI unit

A

Curie (Ci), Becquerel (Bq)

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22
Q

a badge special film that is particularly sensitive to x-rays

A

film badge

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23
Q

_______ on exposed and processed film is related to exposure received by operator

A

optical density

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24
Q

what does TLD stand for?

A

thermoluminscence dosimeter

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25
Q

when TLD is exposed, it absorbs energy and stores it as _______

A

excited electrons

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26
Q

_______ of TLD provides the dose received by operator

A

intensity of light

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27
Q

OSL is stimulated with ____

A

LED

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28
Q

radiation produces ionizations/excitations of essential molecules, such as…

A

DNA, enzymes, ATP, etc.

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29
Q

damage to ____ is much worse than damage to _____

A

DNA, cell membrane

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30
Q

effect in which damage/mutation occurs at the site where radiation is deposited

A

direct effect

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31
Q

effect in which radiation initially acts on water molecules to cause ionization

A

indirect effect

32
Q

____ direct effects; __ indirect effects

A

1/3; 2/3

33
Q

direct effects of radiation characteristics…

A
  • generates free radicals
  • free radicals either dissociate or cross link
  • altered biological molecules differ from original molecules (structure/function)
34
Q

indirect effects of radiation characteristics…

A
  • body is 70% water
  • high likelihood that x-ray photons will interact with water in body
  • radiolysis of water
35
Q

indirect effects of radiation produces (from radiolysis of water)

A

hydroperoxyl, hydrogen peroxide (both are oxidizing agents and toxins)

36
Q

do you need to know the direct/indirect effect equations on the PPT?

A

no, you don’t. don’t stress! :)

37
Q

radiation effects types (2); which is more damaging?

A

short term, long term: long term more damaging

38
Q

types of long term effects

A

cancer, genetic mutation, mental/physical retardation of children

39
Q

cancer may occur ____ years later from exposure

A

10-30

40
Q

histologically, radiation induced cancers are _______ than other cancers

A

not different

41
Q

probability of cancer/genetic mutation increases with ________, but severity does not depend on ________

A

increasing the dose, the amount of the dose

42
Q

random; having a random probability distribution that may not be predicted precisely; unpredictable

A

stochastic

43
Q

a somatic effect that increases in severity with increasing absorbed dose

A

deterministic effects

44
Q

examples of deterministic effects

A

cataract, skin erythema, fibrosis, abnormal growth

45
Q

deterministic effects are not by ____ but are a _____

A

chance, “will-happen” event

46
Q

deterministic effects usually (are/are not) from diagnostic radiology

A

are not

47
Q

if radiation damage to DNA is severe enough, __________ may be detected, but DNA molecules can be damaged ______

A

visible chromosomes aberration; without chromosome aberration

48
Q

effect of radiation on individual gene

A

point mutation

49
Q

result of point mutation

A
  • loss of gene/set of gene
  • mutation in gene/set of genes

…and the cell may exhibit abnormal function

50
Q

several kinds of alterations in the chromosomes have been described

A

chromosome alteration

51
Q

effect of chromosome alterations

A
  • breaking of one or more chromosome

- broken ends seem to possess ability to join together again after separation

52
Q

in chromosome aberration…
if damage is after DNA synthesis, then _____
if damage is before DNA synthesis, then ____

A 
after = only one arm of chromosome is broken
before = both arms of chromosome are broken
53
Q

chromosome repair without errors

A

restitution

54
Q

chromosome “repair”/error with loss

A

deletion (losing part of structure)

55
Q

if there is more than one break in chromosome, _____ may occur

A

broken fragments joining in different combinations

56
Q

illegitimate union characteristics…

A
  • defectively repaired chromosome
  • pre-replication
  • 1 break in each chromosome
  • causes U-shaped and extra
57
Q

ring formation, acentric fragment characteristics…

A
  • defectively repaired chromosome
  • pre-replication
  • breaks in each arm of the same chromosome
58
Q

translocation characteristics…

A
  • defectively repaired chromosome
  • 2 different pre-replication
  • 1 break in each chromosome
  • “swapped” appearance
59
Q

a large proportion of damage will result in mis-repair which can result in the formation of _______ that cause _____

A

gene/chromosomal mutations, malignant development (cancer)

60
Q

ionizing radiation also affect cell division, resulting in _____, and thus _____. This is the basis of ____

A

arrested mitosis, retardation of growth, radiotherapy of neoplasms

61
Q

cells are more sensitive to radiation during the _____________

A

last part of resting phase, early part of prophase

62
Q

to stop cancer cells from repairing themselves (in radiotherapy), you must give ________

A

fractionated dose (multiple doses/not all at once)

63
Q

Bergonie/Tribondeu key statement: “cells are sensitive to radiation ____________ and in _____________”

A

in proportion to their proliferative activity, inverse proportion to their degree of differentiation

64
Q

rapidly dividing are ____ than more differentiated, slowly dividing cells

A

more sensitive

65
Q

____ are radiosensitive, ____ are radioresistant

A

stem cells, mature cells

66
Q

younger tissues/organs are _____

A

radiosensitive

67
Q

tissues with high metabolic rate are ____

A

radiosensitive

68
Q

high proliferation/high growth rate are ______

A

radiosensitive

69
Q

notable Bergonie/Tribondeu

A

lymphocyte

70
Q

lymphocyte is…

A
  • not capable of proliferative activity
  • is a differentiated cell
  • one of the most radiosensitive cells in body
71
Q

highly radiosensitive

A
  • lymphoid organs
  • bone marrow
  • testes
  • intestine
  • mucous membrane
72
Q

intermediate radiosensitive

A
  • fine vasculature
  • growing cartilage
  • growing bone
  • salivary glands
  • lungs
  • kidney liver
73
Q

low radiosensitive

A
  • optic lens
  • mature erythrocytes
  • muscle cells
  • neurons
74
Q

cell death for differentiated (nerve, muscle, secretory, etc.) cells = _____

A

loss of function

75
Q

cell death for proliferating cells (stem cells, intestinal cell) =

A

loss of capacity for proliferation (also known as reproductive death)

76
Q

densely ionizing =

sparsely ionizing =

A 
densely = neutrons, alpha rays
sparsely = x-rays
77
Q

cytoplasmic changes play a _____ in arrested mitosis and cell death

A

minor role

x.umn radiology (15 decks)

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