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Flashcards in Ionizing Radiation Protection Deck (136):
1

Definition of Isotones

Same number of neutrons, Different number of Protons (e.g. 3H, 4He)

2

Low LET for electrons set in motion by Co-60 vs. High LET alpha

Co-60 emits a 2 ~1.25 MeV gammas. Low LET for electrons set in motion ~ 0.25 Kev/micrometer. High LET alpha is 1000x that. So a 2 MeV alpha will set electrons in motion at 250 KeV/micrometer

3

Absorption by a medium of kinetic energy from a high energy charged particle through excitation and ionization

Definition of "Dose"

4

Define 'Secular Equilibrium'

When the half life of the parent is very much greater than that of the daughter half life. After ~7 half lives, the activity of the daughter = activity of the parent

5

Radioactive decay is affected only by

Conditions within the nucleus

6

Approximate diameter of an atomic nucleus

1E-12 cm

7

Approximate diameter of an atom

1E-8 cm

8

Most predominate constituent of primary cosmic radiation

Protons

9

Cosmic radiation accounts for approximately ____ mrem per year at sea level?

26. This number roughly doubles for every 2000 meters increase in altitiude. e.g. Denver ~50 mrem

10

Numerical value of Quality Factor (Q) is based partly on:

Biological effect and judgment. Q is not experimentally determined.

11

KERMA is the sum of the initial kinetic energy of all charged particles liberated by:

Uncharged ionizing radiation

12

The Stopping Power for electrons _____ as the atomic number of the absorber _____

decreases, increases. Stopping Power ~ hinderance

13

Bremmsstrahlung predominantly occurs at beat energies greater than:

1 MeV

14

Average energy of a positron emitted during positron decay:

2/5 or 0.4 of its max

15

For an alpha particle to penetrate the dead layer of skin, it must have an energy of at least:

7.5 MeV

16

Define Internal Conversion as it related to an atom's decay

The nucleus transfers its energy to an orbital electron, which is then ejected

17

Name and list the multiple factor for the 3 naturally occurring decay series and the 1 artificially produced series

Actinium (4n+3), Uranium (4n+2), Neptunium (4n+1) artificially produced, and Thorium (4n). Think A.U.N.T.

18

SI unit for energy

Joule. English system is Erg

19

Isobar

Same Atomic Mass Number e.g. 14C, 14N

20

Isotope

Same number of Protons e.g. 32P, 33P

21

Isomer

Same Mass and Atomic Number, different Meta-Stable states e.g. 99mTc and 99Tc

22

Definition of a Hot Particle

Discrete radioactive fragment that is insoluble in water and is less than 1mm

23

Minimum mass of material which sustains a nuclear chain reaction

Critical Mass. Made up of fissile isotope, isotope enrichment, geometry, presence and types of moderator and reflector material.

24

Primary isotopes of natural uranium whose natural abundances are 99.23729, 0.7206, and 0.0057

U-238, U-235, and U-234

25

Radioactive atoms that have a neutron to proton ratio that is too large will decay by

Beta Minus Decay

26

Define elastic scattering in relation to photons

No energy change of scattered photon. Photon may change direction, but not energy

27

Name the initial and final nuclide in the Thorium Decay series

Th-232, Pb-208

28

Dose equivalent to the U.S. population from all man-made sources of radiation is given by the NRCRP as:

60 mrem/year. Average annual exposure is 360 mrem: 300 mrem is due to natural sources. 60 mrem is man-made exposure, 53 of which is due to medical use.

29

What is the main factor determining the amount of energy that can be transferred to the electron during Compton scattering?

Scattering angle. Scattering angle of incident photon is inversely proportional to the energy of the scattered photon

30

What is a neutrino?

Massless particle- product of beta decay

31

The antineutrino is associated with what process?

Beta Minus decay

32

In the energy range from 0.1 to 5 MeV in either air or water, the most predominant photon interaction is

Compton Scattering

33

Process in which the parent radionuclide has a shorter half life than that of the daughter, but same order of magnitude:

No equilibrium

34

Following electron capture, what processes may occur?

Characteristic X-rays are emitted, Auger electrons emitted, Z deceases by 1

35

Average energy required to produce an ion pair in air by X or gamma radiation:

33.7 eV - Also called the 'W" value of air

36

All natural radioactive decay series have this in common

All end in a stable isotope of lead

37

A positron and an electron interact to produce 2 photons each with an energy of 0.511 MeV. What is this called?

Annihilation reaction

38

What does an alpha emission consist of

2 neutrons, 2 protons - essentially a helium atom without the electrons

39

Radium-226 decays by alpha to Radium-

222. Alphas have an atomic mass of 4 (2 protons, 2 neutrons)

40

When ionizing energy ejects an electron from a water molecule, it makes an H2O+ ion. When an electron is added to a water molecule it makes H2O-. H2O- decomposes into

Free radicals

41

This radionuclide in soil is a major contributor to genetically significant radiation exposure

K-40

42

Most abundant radionuclide in the earth's crust?

Thorium 232. Followed by Nat U, then K-40

43

Secondary radiation following photoelectric interaction can include:

Characteristic X-rays, Auger electrons

44

Controlling radon exposures in a building means that _______ of the building is to be avoided

depressurization (negative pressure)

45

What would be a good approximation of the quality factor of the neutrino?

0. Neutrinos have essentially zero probability of interaction

46

The range of a 2 MeV alpha particle in air is about

1 cm. Range = 0.5cm/MeV below 2.5 MeV
Range = 0.75 cm/MeV above 2.5 MeV

47

One of the processes that increases the proton/neutron ratio in a nucleus involves the conversion of a proton to a neutron. This process is called:

Electron Capture

48

Eventually, charged particles give up their energy to the surrounding medium. In the case of the alpha particle, it becomes (a):

Helium

49

When calculating for structural shielding, the occupancy factor can have a value of:

1, 1/4, 1/16. Full occupancy, T=1 consists of control space, living quarters, waiting rooms, and rest rooms for occupational workers. Partial occupancy, T=1/4, used for utility rooms, restrooms for non-occupational workers. Occasional occupancy T=1/16, stairways, closets.

50

What is the mathmatical relationship between the decay constant and the half live?

Inverse

51

The equivalent energy for the rest mass of a proton is about

938 MeV. The ratio of the mass of the proton to the electron is 1837. The ratio of the energies must be the same (E=mc^2) so: 0.511 MeV*1837 = 938

52

Betas lose most of their energy at:

2/3 max range

53

Underlying principal for measurement of radiation absorbed dose is:

The Bragg-Gray principal. This principle relates absorbed dose in a medium to a measurement of a known amount of ionization in a small volume of a gas filled cavity (usually air).

54

Medical use of byproduct material falls under which 10 CFR?

35

55

10CFR19

Notices, Instructions, Reports to Workers

56

10CFR20

Standards for protection against radiation

57

10CFR30

Licensing of byproduct material

58

A positron has the same mass as a

Beta particle

59

What happens to the incident photon in the compton process?

Partial absorption of the photon energy. Photon and electron are scattered (share energy - binding energy of the electron)

60

Fraction of atoms which undergo decay per unit time is the

Decay constant

61

Most common ionizing radiation hazard associated with anti-static devices

Alpha particles

62

What is the "photoelectric effect" in regard to ionizing radiation?

Total absorption of incident photon energy. Low energy photons collide with a bound orbital electron and eject it from the atom.

63

What happens to the incident photon in the pair production process?

Conversion of a photon into mass. Occurs in photons that have greater than or equal to 1.022 MeV energy. energy is converted into a pair of electron masses (electron & positron). The positron annihilates with a free electron to produce two 0.511 MeV photons

64

Non-extreta licensed material can be put into the sewage system at a rate of ____ Ci/year/institution

1. An additional 1 curie of C-14 and 5 curies of H-3 is also allowed in the sewer per year.

65

Definition of a nuclide

Nucleus with specific Z and A numbers. Specifies exact number of photons, neutron, energy state. Does not have to be radioactive.

66

When a charged particle strikes an electron knocking it out of its orbital, creating an ion pair, it is called

Direct ionization

67

How does the NRC regulate materials produced in a linear accelerator?

They don't. It is regulated on a state level.

68

How does the NRC regulate X-ray machines

They don't. it is regulated on a state level.

69

Production of a positron is the result of the conversion of a _____ to a _____

Proton, Electron

70

KERMA is expressed in what units?

Joules/kg

71

Name the initial and final nuclides in the neptunium series

Np-237; Bi-209

72

How does a thermoluminescent dosimeter work?

A crystal with an added impurity traps electrons during radiation exposure

73

A radionuclide that is constantly being released by cosmogenic action is

C-14

74

Which effect predominates in the 100 keV - 10 MeV region for photons?

Compton

75

How often should sealed sources be leak tested?

Semi-annually

76

Sealed sources are exempt from leak testing if their half life is less than

30 days

77

Sealed sources are exempt from leak testing if the byproduct material is in the form of:

A gas

78

Sealed sources are exempt from leak testing if source contains _____ or less beta or gamma emitting material or _____ or less of alpha emitting material

100 uCi, 10 uCi

79

Sealed sources are exempt from leak testing if it is a seed of Iridium-192 encased in

Nylon Ribbon

80

Sealed sources are exempt from leak testing if they are in storage and not being used. T/F

True dat

81

Name the initial and final nuclides in the actinium series

U-235; Pb-207

82

Gamma rays get their energy from

Nuclear disintegration

83

What is the Roentgen a measurement of?

The amount of X or Gamma radiation that produces ionization in 1 esu of charge in 1 cc of dry air at STP

84

Which particle is considered to be radioactive by itself?

Neutron. When removed from the nucleus of its atom, the neutron decays with a half life of about 10.4 minutes into a beta particle and a proton.

85

Process in which a longer lived half life decays into a much shorter one:

Secular equilibrium

86

Sr-90 is a _____ emitter

Beta. Sr-90 is a bone seeker. 546 keV max energy

87

Gamma radiation produces ionization by

Photoelectric effect, Compton effect, and Pair Production

88

What is the energy equivalent of the electron?

0.511 MeV

89

Radioactive decay is first order decay. it is also _____ of temperature

Independent

90

The buildup factor, B, in radiation shielding is caused

Bad geometry aka broad beam conditions

91

What is Isomeric decay?

Atomic number and Atomic Mass Number of the daughter is the same as that of the parent. e.g. Gamma ray emission, Internal conversion.

92

Process in which a longer lived half life decays into a much shorter one:

Secular equilibrium

93

Regulations regarding excreta containing medically administered radioactive materials:

Exempt! Can be disposed of in ordinary sewage systems.

94

A buildup factor, B, equal to one in a radiation shielding equation occurs under

Good geometry aka narrow beam conditions

95

Radiation in the visible spectrum that results from the slowing down of charged particles in a medium

Cerenkov Radiation

96

What is a use of a chelating agent?

Chemically bind materials. Used to bind radioactive materials.

97

What effect predominates in the >10 MeV gamma radiation region?

Pair production. Can happen with any gamma above 1.022 MeV, but not primary effect below 10 MeV.

98

Name the first and final member of the Uranium decay series

U-238, Pb-206

99

Electromagnetic radiation produced by the rapid deceleration of charged particles is called _____

Bremsstrahlung

100

'Phantoms' are:

Material used to simulate tissue

101

Plutonium is very toxic

Indeed

102

What is the inelastic scattering of a photon

Decrease in energy of the scattered photon

103

What does the 'Z' represent in reference to an atom or an element or a nuclide?

The Proton number or effective proton number

104

What effect predominates in the 10-100 keV range for photons?

Photoelectric effect

105

The energy distribution of alpha emission is

monoenergetic

106

Define 'High Radiation Area'

Any area with the dose rates greater than 100 mrem/hour at 30 cm from the source.

107

Define' Very High Radiation Area'

An area accessible to individuals in which radiation levels exceed 500 rad (5 gray) in one hour at 1 meter from the source. Requires preface of "GRAVE DANGER"

108

Define 'Radiation Area'

Any area with radiation levels greater than 5 mrem/hr at 30 cm from the source

109

Personnel dosimetry records must be retained:

Until the NRC terminates the pertinent license.

110

Airborne Radioactivity Area must be posted at _____ DAC-hour(s) or _____ DAC-hour(s) to an individual in one week

1, 12. 12 DAC-hours in a 40 hour week can be used to establish a posting threshold of .3 DAC

111

A chemical which as shown some success as an internal chelating agent for plutonium is:

DTPA

112

Linear attenuation coefficient vs. the mass energy absorption coefficient

Linear attenuation coefficient is the sum of absorption and scattering processes. The mass energy absorption coefficient will generally be smaller.

113

Dose limit to member of the public

0.1 rem per year

114

Dose limit to embryo/fetus

0.5 rem occupational (entire pregnancy)

115

Limit for sum of the deep dose equivalent and the committed dose equivalent is

50 rem

116

annual limit for the lens of the eye

15 rem

117

DOE requires posting of airborne radioactivity areas at _____ DAC

0.1 DAC

118

The "institutional monitoring period" for a low-level radioactive waste disposal site which utilizes near-surface disposal is:

100 years. After closure, the site is monitored for a period of five years by the operator. It is then turned over to the state for institutional monitoring for 100 years.

119

Target and filter material used in most x-ray MAMMOGRAPHY machines is,

Molybdenum and Molybdenum.

120

Gamma interaction which is the greatest contributor the buildup factor

Compton scattering

121

Leak test of sealed sources should be sensitive enough to detect

0.005 uCi

122

Secondary protective barriers in medical x-ray facilities are designed to protect persons from

leakage and scattered radiation only. Primary protective barriers are implemented for protection against the primary beam

123

Most to Least effective shielding materials for gamma radiation sources: Lead, iron, concrete, water

Yes

124

Buildup factor typically increases with both the _____ and _____ of the shield

Atomic number, thickness.

125

The minimum recommended face velocity for a fume hood is

125 linear feet per minute.

126

NORM

Naturally Occurring Radioactive Material.

127

TENORM

Technologically Enhanced Naturally Occurring Radioactive Material

128

DOE's yearly administrative control level for TEDE for all DOE activities is

2 rem. Regulatory limit is 5, the administrative control level is in place to ensure ALARA and to follow the 1990 recommendations of the ICRP

129

DOE rad worker has a lifetime exposure that exceeds her age. the worker's exposure for that year shall be limited to:

1 Rem

130

DOE beta-gamma removable contamination limit is:

1000 dpm/100cm^2

131

For diagnostic type x-ray machines, the leakage-radiation at a distance of 1 meter from the target cannot exceed

100 mrad in 1 hour

132

For Therapeutic type x-ray machines operating in the 5-50 kV range, the max leakage rate at any point 5cm from the tube can not exceed

100 mrad in 1 hour

133

For Therapeutic type x-ray machines operating in the 50-500 kV range, the max leakage rate at any point 1 m from the tube can not exceed

1 Rad in one hour. Leakage rate at 5cm cannot exceed 30 rads/hr

134

For Therapeutic type x-ray machines operating in the 500+ kV range, the leakage rate in the region outside the useful beam but within 2m radius circular plane centered on the beam's central axis does not exceed

0.2% of the treated tissue dose rate. Except for this region, the dose rate at 1m from the path does not exceed 0.5% of the treatment dose.

135

Source material

Uranium or thorium or any combination of the two in any physical or chemical form.

136

Reference Man's breathing rate

20,000 ml/min. 1ml = 1cc