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Radiology Physics > Radiation Biology And Protection > Flashcards

Radiation Biology And Protection Flashcards

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1
Q

He discovered the natural radioactivity in 1986 by observing radiation induced erythema on his abdomen from a vial of radium he carried in his best pocket during a trip to london

A

Becquerel

“Becquerel burn”

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2
Q

Biological effect of radiation in which the probability of the effect occurring increases with those rather than its severity

A

Stochastic effect

Example: radiation induced leukemia

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3
Q

Radiation biologic effect in which the severity of the injury increases with those rather than its probability of occurrence

A

Deterministic

Examples are skin erythema fibrosis and hematopoietic damage

Threshold those is an approximation of the laws that would likely result in the specified effect

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4
Q

Interaction of radiation with tissue by production of energetic electrons includes:

A

Excitation, ionization and thermal heating

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5
Q

In low energy electrons, energy deposition along the shorter tracks are referred to as

A

Spurs

With diameters approximately 4 to 5 nm

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6
Q

Complex cluster damage in which groups of several damage nucleotides occur within one or two helical turns of dna is a hallmark of:

A

Ionizing radiation induced dna damage

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7
Q

Radiation interaction wherein the change is said to be due to biological macromolecules such as dna rna or protein becoming ionized or excited by an ionizing particle or photon passing through or near it

A

Direct interaction

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8
Q

Radiation interaction wherein the change is due to damage from medical irridiation caused by interaction with water molecules

A

Indirect interaction

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9
Q

These are extremely reactive chemical species that can undergo variety of chemical reactions

A

Free radicals

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10
Q

Hydrogen donation from thiol compounds will produce a much less reactive or damaging ____

A

Thiyl Radical

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11
Q

In the presence of oxygen, repair is inhibited by chemical transformation into _______

A

Peroxiradical

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12
Q

This states that beyond approximately 100 kev per per millimeter in tissue the RBE decreases with increasing LET

A

Overkill effect

Overkill or wasted dose refers to the deposition of radiation energy in excess of that necessary to produce the maximum biological effect.

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13
Q

Structural changes induced by ionizing radiation

A

Hydrogen bond breakage
Molecular degradation
Intermolecular and intramolecular cross linking

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14
Q

Chromosome breaks produced by radiation do occur and can be observed microscopically during

A

Anaphase and metaphase

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15
Q

Chromosomal damage that occurs before dna replication

A

Chromosome aberrations

Whereas that occurring after dna synthesis is called chromatid aberrations

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16
Q

These are physical or chemical factors that exist before and/or at the time of irradiation

A

Conditional radiosensitivity

Mitigated by observing intervals between doses

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17
Q

Defined as the dose of radiation that produces a given biological response in the absence of oxygen divided by the dose of ignition that produces the same biological response in the presence of oxygen

A

Oxygen enhancement ratio (OER)

DESCRIBES THE RELATIVE EFFECTIVENESS OF RADIATION TO PRODUCE DAMAGE AT VARIOUS OXYGEN TENSIONS

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18
Q

This includes biological factors that are characteristics of the cells themselves such as mitotic rate the degree of differentiation and the stage of the cell cycle

A

Inherent radiosensitivity

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19
Q

The law of Bergonie and Tribondue states that

A

Radio sensitivity is greatest for doses that
-have a high mitotic rate
-have a long mitotic future
-are undifferentiated

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20
Q

General cells are most sensitive to radiation during

A

M phase
Gap between s and g2

21
Q

Phenomenon in which irradiated cells or tissues can produce the literacy effects on non irradiated cells

A

Bystander effect/Abscopal/out of field effect

22
Q

Epilation or temporary hair loss can occur

A

Approximately 3 weeks after exposure to 3 to 6 Gy radiation dose

With the growth beginning approximately 2 months later and complete within 6 to 12 months

23
Q

Manifestations of moderately large doses approximately 40 Gy over a period of 4 weeks or 10 Gy in a single dose

A

Intense erythema followed by an acute radiation dermatitis and moist gas formation

Characterized by edema, dermal hypoplasia, inflammatory cell infiltration, damage to vascular structures and permanent hair loss

24
Q

Repeated low level exposures 10 to 20 mGy per day where the total dose approaches 20Gy or more

A

Chronic radiation dermatitis

25
Q

Temporary and permanent sterility can occur after acute doses of approximately

A

Temporary 500 mGy
Permanent 6 Gy

26
Q

Most common histologic type of radiation induced thyroid cancer

A

WELL DIFFERENTIATED PAPILLARY THYROID CARCINOMA

27
Q

Defined as the dose required per generation to double the spontaneous mutation rate

A

DOUBLING DOSE

28
Q

Most sensitive times of exposure for humans during preimplantation

A

12hrs after conception (one cell stage)
30-60hrs (1st two divisions)

29
Q

Spontaneous abortion during preimplantation period requires _____ dose

A

50-100mGy

After implantation it requires dose > 250mGy

30
Q

Primordial radionuclides:

A

Potassium 40 Half life= 1.28 x 109yrs)
Uranium 238 Half life= 4.51 x 109yrs)
Thorium 232 Half life= 1.41 x 1010yrs)

31
Q

Tobacco leaves and cigarette smoke contains this 2 alpha-emitting radionuclides

A

Pb-210, Po-210

32
Q

Consists of a small sealed packet of radiation sensitive film, similar to dental x-ray film, placed inside a special plastic holder and uses film emulsion with Silver bromide grains

A

FILM BADGES

33
Q

Contains storage phosphors in which a fraction of the electrons raised to excited states by ionizing radiation, become trapped in excited states

A

Thermoluminescent dosimeter

34
Q

Most commonly used tld material for personnel dosimetry

A

LiF (Lithium fluoride)

35
Q

Osm is similar to that of tld except that the release of trap electrons and light emission are simulated by laser light instead of heat. It utilizes this compound which is capable of detecting losses as low as 10ùSv

A

Crystalline aluminum oxide activated with carbon

36
Q

Relatively new technology in which a non-volatile analog memory cell surrounded by a gas filled ion chamber is used to record radiation exposure

A

Direct ion storage dosimeter

Disadvantages includes inability to measure beta radiation exposure

37
Q

This principle states that any decision that alters the radiation exposure situation should do more good than harm, that is yield an individual or societal benefit that is higher than the detriment it causes.

A

Principle of justification

38
Q

This principle states that in plant situations the total dose to any individual from all the regulated sources should not exceed the appropriate regulatory limits.

A

Principle of limitation of maximum doses

39
Q

What are the four principal methods by which radiation exposures to persons can be minimized

A

-reducing time of exposure
-increasing distance
-use of shielding
-controlling contamination by radioactive material

40
Q

This law states that exposure rate decreases as the distance from the source is squared

A

Inverse square law

41
Q

Give the shielding design goal for controlled areas uncontrolled areas and radiographic film storage room

A

Controlled area 5 mGy per year
Uncontrolled area should be 1 mGy per year
Film storage area should be less than 0.1 mGy

42
Q

Gonadal shield must attenduate primary nation and its thickness must be equivalent to at least

A

0.5 mm of lead

43
Q

Alara stands for

A

As low as reasonably achievable

44
Q

In evaluating a pregnant and possible pregnant patients the pregnancy test should be obtained within ____ hours before examination

A

72 hours

45
Q

This is the most common encountered tissue reaction following high dose image guided interventional procedure (deterministic effect)

A

Skin damage

46
Q

In using direct ion storage decimeter to measure the radiation exposure, which of the following is a disadvantage of this technology?

A. Broad dose and photon energy response range
B. Unlimited real time dose readings without the need for a special reader
C. Elimination of the periodic distribution and collection of dosimeters
D. The current version cannot be used to measure exposure to beta radiation

A

D

47
Q

Acute radiation dose for neurovascular syndrome

A

> 50 Gy

48
Q

Among the personnel monitoring methods this provide a permanent recording

A. Film badge
B. Osl
C. Tld
D. Pocket dosimeter

A

A

Pocket dosimeter a type of direct ion storage device that allows direct reading of exposure however it cannot measure beta radiation

Osl have the advantage to distinguish static and dynamic exposures and the ability to reread

Tld more common but more expensive than film. Used for phantom and patient dosimetry

49
Q

P

A

Radiology Physics (6 decks)

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