Ionizing Radiation Protection

Question 1

Definition of Isotones

Rev. 1

Answer 1

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

Question 2

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

Answer 2

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

Question 3

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

Rev. 1

Answer 3

Definition of “Dose”

Question 4

Define ‘Secular Equilibrium’

Rev. 1

Answer 4

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

Question 5

Radioactive decay is affected only by

Rev. 1

Answer 5

Conditions within the nucleus

Question 6

Approximate diameter of an atomic nucleus

Rev. 1

Answer 6

1E-12 cm

Question 7

Approximate diameter of an atom

Rev. 1

Answer 7

1E-8 cm

Question 8

Most predominate constituent of primary cosmic radiation

Rev. 1

Answer 8

Protons

Question 9

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

Rev. 1

Answer 9

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

Question 10

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

Rev. 1

Answer 10

Biological effect and judgment. Q is not experimentally determined.

Question 11

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

Rev. 1

Answer 11

Uncharged ionizing radiation

Question 12

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

Rev. 1

Answer 12

decreases, increases. Stopping Power ~ hinderance

Question 13

Bremmsstrahlung predominantly occurs at energies greater than:

Rev. 1

Answer 13

1 MeV

Question 14

Average energy of a positron emitted during positron decay:

Rev. 1

Answer 14

2/5 or 0.4 of its max

Question 15

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

Rev. 1

Answer 15

7.5 MeV

Question 16

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

Rev. 1

Answer 16

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

Question 17

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

Rev. 1

Answer 17

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

Question 18

SI unit for energy

Rev. 1

Answer 18

Joule. English system is Erg

Question 19

Isobar

Rev. 1

Answer 19

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

Question 20

Isotope

Rev. 1

Answer 20

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

Question 21

Isomer

Rev. 1

Answer 21

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

Question 22

Definition of a Hot Particle

Rev. 1

Answer 22

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

Question 23

Minimum mass of material which sustains a nuclear chain reaction

Rev. 1

Answer 23

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

Question 24

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

Rev. 1

Answer 24

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

Question 25

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

Rev. 1

Answer 25

Beta Minus Decay

Question 26

Define elastic scattering in relation to photons

Rev. 1

Answer 26

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

Question 27

Name the initial and final nuclide in the Thorium Decay series

Rev. 1

Answer 27

Th-232, Pb-208

Question 28

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

Rev. 1

Answer 28

300 mrem/year. Total average annual exposure is 620 mrem:

Question 29

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

Rev. 1

Answer 29

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

Question 30

What is a neutrino?

Rev. 1

Answer 30

Massless particle- product of beta decay

Question 31

The antineutrino is associated with what process?

Rev. 1

Answer 31

Beta Minus decay

Question 32

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

Rev. 1

Answer 32

Compton Scattering

Question 33

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

Rev. 1

Answer 33

No equilibrium

Question 34

Following electron capture, what processes may occur?

Rev. 1

Answer 34

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

Question 35

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

Rev. 1

Answer 35

33.7 eV - Also called the ‘W” value of air

Question 36

All natural radioactive decay series have this in common (not neptunium)

Rev. 1

Answer 36

All end in a stable isotope of lead

Question 37

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

Rev. 1

Answer 37

Annihilation reaction

Question 38

What does an alpha emission consist of

Rev. 1

Answer 38

2 neutrons, 2 protons - essentially an energetic helium atom without the electrons

Question 39

Radium-226 decays by alpha to Radium-

Rev. 1

Answer 39

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

Question 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

Rev. 1

Answer 40

Free radicals

Question 41

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

Rev. 1

Answer 41

K-40

Question 42

Most abundant radionuclide in the earth’s crust?

Rev. 1

Answer 42

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

Question 43

Secondary radiation following photoelectric interaction can include:

Rev. 1

Answer 43

Characteristic X-rays, Auger electrons

Question 44

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

Rev. 1

Answer 44

depressurization (negative pressure)

Question 45

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

Rev. 1

Answer 45

0. Neutrinos have essentially zero probability of interaction

Question 46

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

Rev. 1

Answer 46

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

Range = 0.75 cm/MeV above 2.5 MeV

Question 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:

Rev. 1

Answer 47

Electron Capture

Question 48

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

Rev. 1

Answer 48

Helium atom

Question 49

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

Rev. 1

Answer 49

1, 1/4, 1/16, 1/40. 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. No occupancy T=1/40, parking lots

Question 50

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

Rev. 1

Answer 50

Inverse

Question 51

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

Rev. 1

Answer 51

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

Question 52

Betas lose most of their energy at:

Rev. 1

Answer 52

2/3 max range

Question 53

Underlying principal for measurement of radiation absorbed dose is:

Rev. 1

Answer 53

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).

Question 54

Medical use of byproduct material falls under which 10 CFR?

Rev. 1

Answer 54

35

Question 55

10CFR19

Rev. 1

Answer 55

Notices, Instructions, Reports to Workers

Question 56

10CFR20

Rev. 1

Answer 56

Standards for protection against radiation

Question 57

10CFR30

Rev. 1

Answer 57

Licensing of byproduct material

Question 58

A positron has the same mass as a

Rev. 1

Answer 58

Beta particle

Question 59

What happens to the incident photon in the compton process?

Rev. 1

Answer 59

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

Question 60

Fraction of atoms which undergo decay per unit time is the

Rev. 1

Answer 60

Decay constant

Question 61

Most common ionizing radiation hazard associated with anti-static devices

Rev. 1

Answer 61

Alpha particles

Question 62

What is the “photoelectric effect” in regard to ionizing radiation?

Rev. 1

Answer 62

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

Question 63

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

Rev. 1

Answer 63

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

Question 64

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

Rev. 1

Answer 64

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

Question 65

Definition of a nuclide

Rev. 1

Answer 65

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

Question 66

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

Rev. 1

Answer 66

Direct ionization

Question 67

How does the NRC regulate materials produced in a linear accelerator? - Possibly Wrong Don’t Use -Sam

Answer 67

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

Question 68

How does the NRC regulate X-ray machines

Rev. 1

Answer 68

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

Question 69

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

Rev. 1

Answer 69

Proton, Electron

Question 70

KERMA is expressed in what units?

Rev. 1

Answer 70

Joules/kg

Question 71

Name the initial and final nuclides in the neptunium

Rev. 1 series

Answer 71

Np-237; Bi-209

Question 72

How does a thermoluminescent dosimeter work?

Rev. 1

Answer 72

A crystal with an added impurity traps electrons during radiation exposure

Question 73

A radionuclide that is constantly being released by cosmogenic action is

Rev. 1

Answer 73

C-14

Question 74

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

Rev. 1

Answer 74

Compton

Question 75

How often should sealed sources be leak tested?

Rev. 1

Answer 75

Semi-annually

Question 76

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

Rev. 1

Answer 76

30 days

Question 77

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

Rev. 1

Answer 77

A gas

Question 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

Rev. 1

Answer 78

100 uCi, 10 uCi

Question 79

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

Rev. 1

Answer 79

Nylon Ribbon

Question 80

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

Rev. 1

Answer 80

True dat

Question 81

Name the initial and final nuclides in the actinium series

Rev. 1

Answer 81

U-235; Pb-207

Question 82

Gamma rays get their energy from

Rev. 1

Answer 82

Nuclear disintegration

Question 83

What is the Roentgen a measurement of?

Rev. 1

Answer 83

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

Question 84

Which particle is considered to be radioactive by itself?

Rev. 1

Answer 84

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.

Question 85

Sr-90 is a _____ emitter

Rev. 1

Answer 85

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

Question 86

Gamma radiation produces ionization by

Rev. 1

Answer 86

Photoelectric effect, Compton effect, and Pair Production

Question 87

What is the rest energy equivalent of the electron?

Rev. 1

Answer 87

0.511 MeV

Question 88

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

Rev. 1

Answer 88

Independent

Question 89

The buildup factor, B, in radiation shielding is caused by

Rev. 1

Answer 89

Bad geometry aka broad beam conditions

Question 90

What is Isomeric decay?

Rev. 1

Answer 90

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

Question 91

Regulations regarding excreta containing medically administered (in humans) radioactive materials:

Rev. 1

Answer 91

Exempt! Can be disposed of in ordinary sewage systems.

Question 92

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

Answer 92

Good geometry aka narrow beam conditions

Question 93

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

Rev. 1

Answer 93

Cerenkov Radiation. Occurs when a charged particles moves faster in a medium than the phase velocity of light in the same medium.

Question 94

What is a use of a chelating agent?

Rev. 1

Answer 94

Chemically bind materials. Used to bind radioactive materials.

Question 95

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

Rev. 1

Answer 95

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

Question 96

Name the first and final member of the Uranium decay series

Rev. 1

Answer 96

U-238, Pb-206

Question 97

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

Rev. 1

Answer 97

Bremsstrahlung

Question 98

‘Phantoms’ are:

Rev. 1

Answer 98

Material used to simulate tissue

Question 99

Plutonium is very toxic

Rev. 1

Answer 99

Indeed

Question 100

What is the inelastic scattering of a photon

Rev. 1

Answer 100

Decrease in energy of the scattered photon

Question 101

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

Rev. 1

Answer 101

The Proton number or effective proton number

Question 102

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

Rev. 1

Answer 102

Photoelectric effect

Question 103

The energy distribution of alpha emission is

Rev. 1

Answer 103

monoenergetic

Question 104

Define ‘High Radiation Area’

Rev. 1

Answer 104

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

Question 105

Define’ Very High Radiation Area’

Rev. 1

Answer 105

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”

Question 106

Define ‘Radiation Area’

Rev. 1

Answer 106

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

Question 107

Personnel dosimetry records must be retained:

Rev. 1

Answer 107

Until the NRC terminates the pertinent license.

Question 108

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

Rev. 1

Answer 108

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

Question 109

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

Rev. 1

Answer 109

DTPA

Question 110

Linear attenuation coefficient vs. the mass energy absorption coefficient

Funky answer - needs followup - Sam

Answer 110

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

Question 111

Dose limit to member of the public

Rev. 1

Answer 111

0.1 rem per year

Question 112

Dose limit to embryo/fetus

Rev. 1

Answer 112

0.5 rem occupational (entire pregnancy)

Question 113

Limit for sum of the deep dose equivalent and the committed dose equivalent to any individual organ or tissue other than the lens of the eye

Rev. 1

Answer 113

50 rem

Question 114

annual limit for the lens of the eye

Rev. 1

Answer 114

15 rem

Question 115

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

Needs verification - Sam

Answer 115

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.

Question 116

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

Rev. 1

Answer 116

Molybdenum and Molybdenum.

Question 117

Gamma interaction which is the greatest contributor the buildup factor

Rev. 1

Answer 117

Compton scattering

Question 118

Leak test of sealed sources should be sensitive enough to detect

Rev. 1

Answer 118

0.005 uCi

Question 119

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

Rev. 1

Answer 119

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

Question 120

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

Rev. 1

Answer 120

Yes

Question 121

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

Rev. 1

Answer 121

Atomic number, thickness.

Question 122

The minimum recommended face velocity for a fume hood is

Rev. 1

Answer 122

125 linear feet per minute.

Question 123

NORM

Rev. 1

Answer 123

Naturally Occurring Radioactive Material.

Question 124

TENORM

Rev. 1

Answer 124

Technologically Enhanced Naturally Occurring Radioactive Material

Question 125

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

Rev. 1

Answer 125

100 mrad in 1 hour

Question 126

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

Rev. 1

Answer 126

100 mrad in 1 hour

Question 127

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

Rev. 1

Answer 127

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

Question 128

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

Rev. 1

Answer 128

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.

Question 129

Source material

Rev. 1

Answer 129

Uranium or thorium or any combination of the two in any physical or chemical form. Must be in natural isotopic concentrations. Depleted uranium is included as source material.

Question 130

Reference Man’s breathing rate

Rev. 1

Answer 130

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