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Radiation Protection > Week 4 - Quantities and Units > Flashcards

Week 4 - Quantities and Units Flashcards

1
Q

Why are there needs to develop standards for measuring and limiting radiation exposure?

A
  • Awareness of potential harmful effects of ionizing radiation
  • Desire of the medical community to reduce radiation exposure
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2
Q

How did Roentgen make his discovery?

A
  • Through use of a Crookes tube, he coated a piece of paper with barium and it was illuminated
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3
Q

What are somatic injuries?

A

Injuries to the body including radiodermatitis and skin cancer

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4
Q

What were some results of excessive occupational radiation exposure for early pioneers?

A
  • Radiodermatitis
  • Cancer
  • Blood disorders (aplastic anemia and leukemia)
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5
Q

What is radiodermatitis?

A

Lesions on fingers induced by ionizing radiation

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5
Q

What is skin erythema dose?

A

The dose which causes reddening of the skin as the upper limit

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6
Q

Why was skin erythema dose determined to be inefficient?

A

It was not reliable because of the varying levels in which people developed erythema

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6
Q

What were qualities needed in a new unit?

A

It needed to be based on some measurable effect produced by radiation, like ionization of atoms or energy absorbed in the irradiated object

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7
Q

What did the International x-ray and radium protection committee precede?

A

The ICRP

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8
Q

What are the early tissue reactions of ionizing radiation?

A
  • Nausea
  • Fatigue
  • Diffuse redness of the skin
  • Loss of hair
  • Intestinal Disorders
  • Fever
  • Blood disorders
  • Shedding of the outer layer of skin
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9
Q

What are the late tissue reactions of ionizing radiation?

A
  • Cataract formation
  • Fibrosis
  • Organ atrophy
  • Loss of parenchymal cells
  • Reduced infertility
  • Sterility
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10
Q

What are Stochastic effects of ionizing radiation?

A
  • Cancer
  • Genetic (hereditary) effects
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11
Q

What is tolerance dose?

A

Radiation dose to which occupationally exposed persons could be subjected to without harmful effects

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12
Q

Why was a replacement for tolerance dose needed?

A

Scientists began to recognize later deterministic somatic effects and late stochastic effects on people

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13
Q

How were dose limits calculated in the 1970s?

A

They were calculated and established to ensure that risk from radiation exposure acquired on the job did not exceed risks encountered in safe occupations

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14
Q

What are the traditional non-metric units of radiation?

A
  • Exposure (X) - measured in R
  • Absorbed dose (D) - measured in Rad
  • Equivalent dose (EqD) - measured in REM
  • Effective dose (EfD) - measured in REM
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15
Q

What are the radiation quantities in use today?

A
  • Exposure (X)
  • Air kerma
  • Absorbed Dose (D)
  • Equivalent dose (EqD)
  • Effective dose (EfD)
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16
Q

What happened in the Radiology Field in 1895?

A

X-rays were discovered

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17
Q

What happened in the Radiology Field in 1896?

A

The first case of somatic damage was reported in Europe

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18
Q

What happened in the Radiology Field in 1900?

A

Skin erythema became the unit for measuring exposure

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19
Q

What happened in the Radiology Field in 1904?

A

Clarence Dally because the first American radiation fatality

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20
Q

What happened in the Radiology Field in 1910?

A

First cancer deaths due to radiation were reported amongst physicians

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21
Q

What happened in the Radiology Field in 1921?

A

British x-ray and radium protection committee was formed to research reducing exposure

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22
Q

What happened in the Radiology Field in 1921?

A

1st international congress on radiology was held in London

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23
Q

What were two outcomes of the 1st international congress on radiology?

A
  • No system for measuring exposure was identified
  • ICRU (international committee on radiation units and measurements was formed)
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24
Q

What happened in the Radiology Field in 1928?

A

2nd international congress on radiology held in Stockholm

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25
Q

What were two outcomes of the 2nd international committee of radiology meeting?

A
  • ICRU was tasked with defining a unit of exposure
  • International x-ray and radium protection committee was established
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26
Q

What happened in the Radiology Field in 1930?

A

Tolerance dose was used for protection purposes

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27
Q

What happened in the Radiology Field in 1931?

A

US formed the US Advisory Committee for x-ray

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28
Q

What happened in the Radiology Field in 1934?

A

Tolerance dose of 0.2 R per day because the standard recommended dose

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29
Q

What happened in the Radiology Field in 1936?

A

Tolerance dose was reduced to 0.1 R per day

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30
Q

What happened in the Radiology Field in 1937?

A

Roentgen became internationally accepted as a measure for exposure to x-ray and gamma rays

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31
Q

What happened in the Radiology Field in 1946?

A

US Advisory Committee for x-ray became the National Committee on Radiation Protection and Measure (NCRP)

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32
Q

What happened in the Radiology Field in 1948?

A

International system of units (SI) is developed

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33
Q

What happened in the Radiology Field in 1950’s?

A

Maximum permissible dose (MPD) replaced tolerance dose for radiation protection purposes

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34
Q

What happened in the Radiology Field in 1962?

A

Roentgen was redefined to increase accuracy

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35
Q

What happened in the Radiology Field in 1963?

A

National Committee for Radiation Protection & Measure because the National Council on Radiation protection

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36
Q

What happened in the Radiology Field in 1977?

A

ICRP recommends that dose equivalent limits or effect dose equivalent replace MPD

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37
Q

What happened in the Radiology Field in 1980?

A

ICRU adapted SI units for use with Radiation

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38
Q

What happened in the Radiology Field in 1985?

A

US adopted SI units for use in radiology

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39
Q

What happened in the Radiology Field in 1991?

A

ICRP replaces effective equivalent dose with Effective Dose

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40
Q

When was Skin Erythema dose used to measure dose limits?

A

1900-1930

41
Q

When was Tolerance dose used to measure radiation?

A

1930-1950

42
Q

When was maximum permissible dose used to measure radiation?

A

1950-1977

43
Q

When was effective dose equivalent used to measure radiation?

A

1977-1991

44
Q

What has been used to measure radiation from 1991-present?

A

Effective Dose

45
Q

What is Exposure?

A

The total electrical charge (All + or all -) per unit mass that x-ray photons up to 3 million eV generated in dry, standard temp/pressure

46
Q

How can Exposure (X) be defined further?

A

It is a radiation quantity, that expresses the concentration of radiation delivered to a specific area

47
Q

What information must be obtained about an x-ray beam?

A

The amount of ionization the beam produces in a known mass of air

48
Q

How is the measurement of beam ionization obtained?

A

In an accredited calibration laboratory using standard, or free-air ionization chamber

49
Q

How does an ionization chamber work to measure radiation exposure by the amount of ionization an x-ray beam produces?

A

The chamber consists of a box with a known quantity of air, two oppositely charged metal plates and an electrometer, which measures the amount of charge collected on a positively charged plate

50
Q

What is Coulomb (C)?

A

The basic unit of electrical charge

51
Q

What do Coulombs represent?

A

The quantity of electrical charge flowing past a point in a circuit in 1 second when an electrical current of 1 ampere is used

52
Q

What is ampere?

A

The SI unit of electrical current

53
Q

What is the conversion from R to C/kg?

A

1 R = 2.58 × 10−4 C/kg of air

54
Q

What is C/kg used for?

A

X-ray equipment calibration and to calibrate radiation survey equipment

55
Q

What is air karma?

A

The SI quantity used to express how energy is transferred from a beam of radiation to a material such as patient skin

56
Q

Why is air kerma important?

A

It denotes a calculation of radiation intensity in air

57
Q

What can air kerma be used for?

A

To express x-ray tube output and inputs to the image receptor

58
Q

What are the acronyms for kerma?

A
  • Kinetic energy released in matter
  • Kinetic energy release in material
  • Kinetic energy released per unit mass
59
Q

What is air kerma expressed in?

A

Joule per kilogram (J/kg)

60
Q

What else can air kerma be expressed in?

A

Gray (Gy)

61
Q

What is Gy(a)/?

A

Used to indicated kinetic radiation energy deposited or absorbed in a mass of air

62
Q

What is Gy (t)?

A

Used to indicated kinetic radiation energy deposited or absorbed in a mass of tissue

63
Q

What is Dose Area Product? (DAP)

A

The sum total of air kerma over the exposed areas of the patient’s surface

64
Q

What is DAP usually specified in?

A

Units of mGY-cm^2

65
Q

What is absorbed dose?

A

The amount of energy per unit mass absorbed by an irradiated object

66
Q

What is absorbed dose responsible for?

A

Any biologic damage resulting from exposure of the tissues to radiation

67
Q

What does absorbed dose depend on?

A
  • Atomic number of the tissue comprising the structure
  • Mass density of the tissue
  • Energy of the incident photon
68
Q

What is the SI unit of absorbed dose?

A

Gy

69
Q

What can units of absorbed dose be used to measure?

A

The energy deposited by any form of radiation

70
Q

What are the subunits used to indicated absorbed dose values?

A

-centigray (cGy) - 1/100
- milligray (mGy) - 1/1000
- micorgray (uGy) 1/1,000,000

71
Q

What is the subunit conversion of Rad to centigray?

A

Number of rad / 1 = Number of cGy

72
Q

What is surface integral dose? (SID)

A

The total amount of radiant energy transferred by ionizing radiation to the body during exposure

73
Q

What is the equivalent SI unit for SID?

A

Gy-m^2

74
Q

What is quality factor?

A

(Q) is an adjustment multiplier that is employed in the calculation of dose equivalence to detail the specific ability of a dose of any kind of ionizing radiation to cause biologic damage.

75
Q

Which types of ionizing radiation have a quality factor of 1?

A

X-ray photons
Beta particles
Gamma photons
High-energy external photons

76
Q

Which types of ionizing radiation have a quality factor of 5?

A

Thermal neutrons

77
Q

Which types of ionizing radiation have a quality factor of 20?

A

Fast neutrons
Low-energy internal photons
Alpha particles
Mult. Charged particles of unknown energy

78
Q

What is linear energy transfer? (LET)

A

The amount of energy transferred on averaged by incident radiation to an object per unit length of track through the object

79
Q

What is LET expressed in?

A

kiloelectron volts per micrometer

80
Q

What is the general rule of LET?

A

Radiation with higher LET transfer a large amount of energy into a small area and can do more biologic damage

81
Q

What is equivalent dose? (EqD)

A

The product of the average absorbed dose (D) in a tissue and its associated Wr (weighing factor) chose for that type

82
Q

What is the formula for EqD?

A

EqD = D x Wr and Sv = Gy X Wr

83
Q

What is Radiation Weighing Factor (Wr)?

A

A dimensionless factor used for radiation protection purposes to account for differences in biologic impact amongst various types of ionizing radiation

84
Q

Which types of radiation type/energy ranges have a Wr of 1?

A

x-ray and gamma ray photons and electrons (Every energy)

85
Q

Which types of radiation type/energy ranges have a Wr of 2?

A

Protons

86
Q

Which types of radiation type/energy ranges have a Wr of 5?

A
  • Neutrons, energy <10 keV
  • > 20 MeV
87
Q

Which types of radiation type/energy ranges have a Wr of 10?

A
  • 10 keV-100keV
  • > 2 MeV-20MeV
88
Q

Which types of radiation type/energy ranges have a Wr of 20?

A
  • > 100 keV - 2 MeV
  • Alpha particles
89
Q

What is effective dose? (EfD)

A

A measure of the overall risk of exposure to humans from ionizing radiation

90
Q

What is the formula for EfD?

A

EfD = D x Wr x Wt

91
Q

What are tissue weighing factors? (Wt)

A

A value that denotes the percentage of the summed stochastic risk stemming from irradiation of tissue to the all-inclusive risk

92
Q

What are the typical values for absorbed dose to skin for AP lumbar spine exam?

A

6.4 mGy

93
Q

What are the typical values for absorbed dose to bone marrow for AP lumbar spine exam?

A

0.6 mGy

94
Q

What are the typical values for absorbed dose to a fetus for AP lumbar spine exam?

A

3.5 mGy

95
Q

What are the typical values for equivalent dose to a fetus for AP lumbar spine exam?

A

3.5 mSv

96
Q

What are the typical values for effective dose for AP lumbar spine exam?

A

3.3 mSv

97
Q

What is Collective EfD used to describe in radiation protection?

A

internal and external dose measurements

98
Q

What is the quantity of Collective EfD used to describe?

A

Radiation exposure of a population or a group from low doses of different sources of ionizing radiation

99
Q

What is the radiation unit for Collective EfD?

A

Person-sievert

100
Q

What is total effective dose equivalent?

A

The sum of effective dose equivalent from external radiation and quantity called committed effective dose equivalent from internal radiation sources

101
Q

What is TEDE?

A

Takes into account all possible sources of radiation exposure and is a useful dose monitor for occupational exposed personnel

Radiation Protection (12 decks)

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