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radiology > Radiation Limitation > Flashcards

Radiation Limitation Flashcards

1
Q

As growth and proliferation rate increase, radio –sensitivity____________(increase/Decrease)

A

Increase

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2
Q

When metabolic activity is high, radio- sensitivity is also low. (True or false)

A

False

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3
Q

Three cardinal principles of radiation protection?

A

Time, distance, and shielding

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4
Q

The product of Exposure rate and Exposure Time will give you the ____________.

A

Occupational exposure

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5
Q

If the distance from the source exceeds five times the source diameter, it can be treated as a _______________

A

Point source

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6
Q

The thickness of the absorber that will reduce the radiation intensity to one-half of its original intensity is known as______________

A

Half value layer (HVL)

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7
Q

The thickness of the absorber that will reduces the radiation intensity to one-tenth of its original intensity is known as ____________

A

Tenth value layer (TVL)

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8
Q

How many half value layers equal a tenth value layer?

A

1 TVL = 3.3HVL

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9
Q

What is the formula to calculate equivalent dose?

A

Equivalent dose= Absorbed dose x Tissue weighting factor

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10
Q

What is the formula to calculate effective dose?

A

Effective dose= Absorbed dose x Radiation weighting factor X Tissue weighting factor

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11
Q

What is the radiation weighting factor for alpha particle?

A

20

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12
Q

What is the radiation weighting factor for gamma rays?

A

1

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13
Q

What is the tissue weighting factor for gonads?

A

0.20

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14
Q

What is the tissue weighting factor for thyroid?

A

0.05

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15
Q

What is the tissue weighting factor for bone marrow?

A

0.12

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16
Q

Occupational effective dose is ________% of the monitor dose.

A

10

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17
Q

Leakage radiation must be less than _____mR/Hour at a distance of 1 meter from the protective housing.

A

100

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18
Q

Leakage radiation must be less than _____mGy/Hour at a distance of 1 meter from the protective housing.

A

1

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19
Q

The SID indicator must be accurate to within_______________

A

2% of the indicated SID

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20
Q

The x-ray beam and light beam must coincide to__________.

A

2% of the SID

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21
Q

PBL must have an accuracy of ___________

2% of the SID

A

2% of the SID

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22
Q

The inherent filtration is _______________equivalent

A

0.5 mm of aluminum

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23
Q

The inherent and added filtration should combine to equal the required _________ equivalent.

A

2.5mm of aluminum

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24
Q

The variation in the x-ray intensity should not exceed___________________

A

5%

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25
Q

The maximum acceptable variation in linearity is _________% from one mA station to an adjacent mA station.

A

10%

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26
Q

Radiation intensity is expressed in units of_____________

A

mR/mAs or mGy/mAs

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27
Q

The exposure switch must allow the operator to remain at least __________from the x-ray tube.

A

2 meters (6 feet)

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28
Q

The SSD must not be less than __________ cm on stationary fluoroscopes.

A

38

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29
Q

The SSD must not be less than___________ on mobile fluoroscopic equipment.

A

30 cm

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30
Q

The _____________________________ serves as a primary protective barrier and it must be ____________mm of lead equivalent.

A

Image intensifier, 2

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31
Q

The exposure switch should be of __________ type.

A

Dead man

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32
Q

The Bucky slot must be covered with at least __________mm of lead equivalent.

A

0.25

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33
Q

The protective curtain must be of at least __________mm of lead equivalent.

A

0.25

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34
Q

A cumulative timer must produce and audible signal when the fluoroscopic time has exceeded __________minutes.

A

5

35
Q

How can you calculate DAP?

A

The absorbed dose multiplied by the tissue irradiated.

36
Q

The intensity of the x-ray beam at the table top should not exceed ______ for each mA of operation at 80kVp (21mGy/min)

A

2.1 R/min

37
Q

The intensity of the x-ray beam at the table top should not exceed ____ for regular fluoroscopy.

A

10 R/min

38
Q

The intensity of the x-ray beam at the table top should not exceed ____ for High level fluoroscopy.

A

20 R/min

39
Q

The Primary protective barrier thickness must be _________

A

1/16 inch of lead

40
Q

Secondary protective barrier thickness must be ________

A

1/32 inch of lead

41
Q

The intensity of scatter radiation at 1 meter from the patient is approximately _______% of the intensity of the useful beam at the patient.

A

0.1

42
Q

An area that is occupied primarily by radiology personnel and patient is known as_________

A

A controlled area

43
Q

Exposure to a radiation worker in the controlled area must be less that _____________/week

A

1mSv (100 mrem)

44
Q

What is the annual recommended occupational dose limit?

A

50mSv

45
Q

Exposure to personnel in the uncontrolled area must be less than _____________/week

A

2mrem

46
Q

What is the unit for work load?

A

mA-minutes/wk

47
Q

The percentage time during which the x-ray beam is on and directed toward a particular protective barrier is known as __________________

A

Use factor

48
Q

__________ is the determination by scientific methods of the amount, rate and distribution of radiation emitted from a source of ionizing radiation.

A

Dosimetry

49
Q

Name three field survey instruments.

A

Ionization chamber type survey meter
Geiger-Mueller counters
Scintillation detectors

50
Q

Geiger-Mueller counter is a good measuring device.( True or False)

A

False

51
Q

Which counter is generally used in Nuclear medicine?

A

Geiger-Mueller counter

52
Q

What crystals are used in scintillation counter?

A

Sodium iodide or cesium iodide crystals

53
Q

Most sensitive detector of alpha and gamma and x- radiation is_________________.

A

Scintillation

54
Q

Which field survey equipment is useful in the detection of lost radiation sources?

A

Scintillation detectors

55
Q

What is Dynode gain?

A

The ratio of secondary electrons to incident electrons.

56
Q

What is hygroscopic means?

A

They absorb moisture and will swell and crack with the absorption of moisture.

57
Q

A _____________________is a device that emits electrons when illuminated by __________.

A

Photocathode, light

58
Q

_______________________is the process of emitting ___________by a photocathode when stimulated by ______________.

A

Photoemission, electrons, light

59
Q

ESD can be calculated using a _______________.

A

Nomogram

60
Q

Average ESD of fluoroscopy is ____________/min.

A

40mGy

61
Q

The average radiation dose to the entire bone marrow is known as ___________________ dose.

A

Mean marrow

62
Q

The US mean marrow dose is_____________________/year.

A

1mGy (100mrad)

63
Q

Increased CT pitch increases patient dose.(True or False)

A

False

64
Q

A pregnant patient is more sensitive during the __________semester

A

First

65
Q

The natural background radiation in the US is _______mSv/yr.

A

3

66
Q

More than 50% of the natural background radiation is from _______________

A

Radon

67
Q

What is ALARA stands for?

A

As Low As Reasonably Achievable

68
Q

Legal Dose Limits in the United States lens of the eye is__________

A

150 mSv/yr (15 rem/yr)

69
Q

Legal Dose Limits in the United States during the entire pregnancy is __________________

A

5 mSv (500 mrem)

70
Q

Legal Dose Limits in the United States for monthly pregnancy is

A

0.5 mSv (50 mrem)

71
Q

What is TLD stands for?

A

Thermoluminescent Dosimeters

72
Q

What crystal is used in a TLD?

A

Lithium Fluoride Crystals

73
Q

Extremity dosimeter (Ring Dosimeter) used in Nuclear medicine is of ____________type.

A

Thermoluminescent Dosimeter

74
Q

What is the minimum dose that can be measured using a TLD?

A

5 mrem

75
Q

What is the minimum dose that can be measured using an OSL?

A

1 mrem

76
Q

What is the minimum dose that can be measured using a Film badge?

A

10mrem

77
Q

How long a TLD can be worn?

A

3 months

78
Q

What is a disadvantage of a TLD?

A

Provide no permanent record

79
Q

Which dosimeter is the most sensitive to low level radiation?

A

Pocket ionization chamber (Self Reading Dosimeter)

80
Q

Which dosimeter should be charged to a predetermined voltage by a special charging unit?

A

Pocket ionization chamber (Self Reading Dosimeter)

81
Q

Which radiation monitor can give immediate reading?

A

Pocket ionization chamber (Self Reading Dosimeter)

82
Q

OSL contains a thin layer of __________detector.

A

Aluminum Oxide

83
Q

What is the lowest level of radiation that can be measured using an OSL?

A

1 mrem

radiology (6 decks)

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