Radiation Biology Flashcards

1
Q

This occurs when an X-ray photon ionizes water which results in the production of hydrogen and hydroxyl free radicals

A

Free radical formation

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2
Q

Uncharted atom or molecule that exists with a single , unpaired electron in its outermost shell ( highly reactive and unstable)

A

Free radical

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3
Q

To achieve stability , the free radicals may :

A

> recombine with other free radicals without causing changes in the molecule
combine with other free radicals and cause changes
combine with ordinary molecules to form a toxin (hydrogen peroxide) capable of producing widespread cellular changes

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4
Q

2 theories of radiation injury

A

Draft theory and indirect theory

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5
Q

Theory where cell damage results when ionizing radiation directly hits critical areas, or targets within the cell

A

Direct theory

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6
Q

Theory where X-ray photon are absorbed within the cell and cause formation of toxins which in turn damage the cell

A

Indirect theory

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7
Q

2 classification of biological effects of radiation

A

Stochastic and deterministic effects

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8
Q

The probability of occurrence increases with the increasing absorbed dose ( cancer and genetic mutation)

A

Stochastic effects

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9
Q

The severity of the response is proportional to the dose (loss of hair, cataract formation, acute radiation syndrome)

A

Deterministic effects

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10
Q

2 radiation effects

A

Somatic and genetic effects

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11
Q

Effects that are seen within minutes, days or weeks after exposure (acute radiation syndrome)

A

Short term effects

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12
Q

Effects that appear after years, decades or generations (cancers, birth abnormalities)

A

Long term effects

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13
Q

Effects on radiation seen on the person irradiated (cancer, cataracts)

A

Somatic effect

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14
Q

Effects not seen on the person irradiated but are passed on to future generations (genetic mutations)

A

Genetic effects

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15
Q

TRUE or FALSE

Nucleus is more radio sensitive than cytoplasm

A

True (sensitive site is the DNA within the chromosomes)

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16
Q

TRUE or FALSE

The type of damage depends on the stage of cell in the cell cycle at time of irradiation

A

True

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17
Q

TRUE or FALSE

Younger the tissue and organ, the more radio resistant

A

False (radio sensitive )

18
Q

TRUE or FALSE

When level of metabolic activity increases, the radiosensitivity decreases

A

False ( also increases)

19
Q

TRUE or FALSE

As the rate for cells and the growth rate for tissue increases, the radiosensitivity increases

20
Q

TRUE or FALSE

Mature cell is more resistant to radiation

21
Q

Radiation effects on cell kinetics

A

Mitosis delay, cell death and recovery

22
Q

Characteristics of most radiosensitive cells

A

> have high mitotic rate
undergo many future mitoses
most primitive in differentiation

23
Q

5 categories of radiosensitivity

A

> vegetative inter mitotic cells - basal cells
differentiating intermitotic cells - spermatocytes
multi potential CT cells - fibroblast
reverting postmitotic cells- parenchymal cells of the liver
fixed postmitotic cells- neurons

24
Q

Severity of damage depends on the amount of radiation received

25
Rate of exposure
Dose rate
26
Rate of loss of energy from a particle as it moves along its track
Linear energy transfer (LET)
27
TRUE or FALSE | Greater cell damage occurs in the presence of oxygen
True
28
2 system used to define radiation measurement
>traditional system ( R, rem, rad) | > systeme Internationale unit (Kerma, sv, gy)
29
Measurement of ionization in air produced by X-rays
Exposure
30
Quantity of x- radiation or gamma radiation that produces and electrical charge of 2.58 x 10-4 coulombs in a kilogram of air at standard temperature and pressure conditions
Roentgen
31
Unit that Measures the kinetic energy from photons to electrons
Kerma
32
What are the HIGH radiosensitive organs
Lymphoid organ, testis, intestine, mucous membrane, bone marrow
33
What are the intermediate radiosensitive organs
Growing cartilage and bones, fine vasculature, liver, lungs, kidney and salivary glands
34
What are the low radiosensitive organs
Optic lens, mature erythrocytes, muscle cells, neurons
35
Amount of energy absorbed by a tissue
Dose
36
This is used to compare the biological effects of 2 different types of radiation to a tissue or organ
Dose equivalent measurement
37
A special unit of dose that is equal to the deposition of 100 ergs if energy per gram of tissues (100 ergs/gm)
Radiation absorbed dose
38
Sum of the products of absorbed dose average over a tissue or organ and a quality factor (QF) or radiation weighting factor (WR) specific for a type of radiation
Rem
39
Dimensionless multiplier used to place the exposure effects of different types of radiation on a common scale
Quality factor
40
This is used to estimate the risk in humans (WT xHT "equivalent dose to each organ or tissue)
Effective dose
41
Critical organs during dental radiograph exposure
Skin, thyroid glands, eyes, bone marrow
42
Study of the effects of ionizing radiation on living systems
Radiation biology