NHR Atomic/Nucelar Structure From 2nd Ed MedDos Cert Study Guide By Rajan

Question 1

One atomic mass unit is equal to:

Answer 1

1.66 x 10^-27kg

From Review of Medical Dosimetry Book by William Amestoy

Question 2

What is the conversion factor from MeV/c2

Answer 2

931

From Review of Medical Dosimetry Book by William Amestoy

Question 3

What is the number of charge of a proton?

Answer 3

+1

From Review of Medical Dosimetry Book by William Amestoy

Question 4

The nucleus of an atom is composed of_____.

Answer 4

Protons and Neutrons

From Review of Medical Dosimetry Book by William Amestoy

Question 5

What is the force that binds electrons to the atom?

Answer 5

Electromagnetic force

From Review of Medical Dosimetry Book by William Amestoy

Question 6

The energy needed to remove an electron from the shell is called_____.

Answer 6

Binding energy

From Review of Medical Dosimetry Book by William Amestoy

Question 7

Electron binding energy increases _____.

Answer 7

In the K shell compared with N shell; is proportional to Z2; with increasing charge of the nucleus.

From Review of Medical Dosimetry Book by William Amestoy

Question 8

The chemical properties of an atom are determined by:

Answer 8

Valence electrons

From Review of Medical Dosimetry Book by William Amestoy

Question 9

The maximum number of electrons that can occupy a specific energy level is determined using the formula

Answer 9

2n²

From Review of Medical Dosimetry Book by William Amestoy

Question 10

What is the maximum number of electrons that can hold in L shell?

Answer 10

8

From Review of Medical Dosimetry Book by William Amestoy

Question 11

The atoms are designated by atomic symbols; the symbol A represents _____.

Answer 11

Mass number and number of protons and neutrons

From Review of Medical Dosimetry Book by William Amestoy

Question 12

In a neutral atom, the number of electrons is equal to _____.

Answer 12

Atomic number

From Review of Medical Dosimetry Book by William Amestoy

Question 13

The number of neutrons in an atom is equal to _____.

Answer 13

A - Z

From Review of Medical Dosimetry Book by William Amestoy

Question 14

In chronological order, identify the number of electrons, number of protons, number of neutrons, it’s mass number, atomic number, and number of nucleons in the following element Gold:

Answer 14

79, 79, 118, 197, 79, 197

From Review of Medical Dosimetry Book by William Amestoy

Question 15

The rest mass of an electron (MeV/c ²) is equal to:

Answer 15

0.511

From Review of Medical Dosimetry Book by William Amestoy

Question 16

A transition is said to have taken place on an atom when_____.

A. An electron is removed from an atom
B. All electrons are in the lowest allowable energy levels
C. An electron moves from its original shell to another
D. Electrons are attracted by the nucleus

Answer 16

C. An electron moves from its original shell to another

From Review of Medical Dosimetry Book by William Amestoy

Question 17

What is the maximum number of electrons allowed in M shell?

Answer 17

18

From Review of Medical Dosimetry Book by William Amestoy

Question 18

An atom which is ionized and loses an electron is called a/an _____.

Answer 18

Positive ion

From Review of Medical Dosimetry Book by William Amestoy

Question 19

Atoms who have nuclei with the same number of protons but different number of neutrons are called _____.

Answer 19

Isotopes

From Review of Medical Dosimetry Book by William Amestoy

Question 20

This is a _____.

Answer 20

Isotone

From Review of Medical Dosimetry Book by William Amestoy

Question 21

True or False: An alpha particle is identical to a helium nucleus with a mass number of 4 and an electrostatic charge of +2.

Answer 21

True

Question 22

True or False: Alpha particles are usually emitted by low-Z radioactive elements during radioactive decay.

Answer 22

False

Question 23

True or False: Alpha emission changes the identity of the radionuclide.

Answer 23

True

Question 24

True or False: Ra^226 is an alpha emitter.

Answer 24

True

Question 25

True or False: Co^60 is an alpha emitter.

Answer 25

False

Question 26

True or False: A beta particle is an electron emitted by the atomic nucleus during a radioactive decay.

Answer 26

True

Question 27

True or False: Co^60 is a beta emitter.

Answer 27

True

Question 28

True or False: Ir^192 is a beta emitter.

Answer 28

True

Question 29

True or False: Emission of beta changes the identity of the radionuclide.

Answer 29

True

Question 30

True or False: A positron is a positively charged particle but identical to an electron in all other respects.

Answer 30

True

Note: the reference says they are practically identical, which to me means it can be argued to be False

Question 31

True or False: Beta decay is usually associated with proton rich radionuclides.

Answer 31

False

Question 32

True or False: Positron decay is usually associated with neutron rich radionuclides.

Answer 32

False

Question 33

True or False: Emission of gamma radiation does not change the identity of the radionuclide.

Answer 33

True

Question 34

True or False: Gamma usually follows beta particle emission in radioactive decay.

Answer 34

True

Question 35

True or False: There are no pure beta emitters.

Answer 35

False

Question 36

True or False: There are no pure gamma emitters.

Answer 36

False

Question 37

True or False: Electron capture usually occurs in high-Z radioactive elements.

Answer 37

True

Question 38

True or False: Electron capture and beta emission are competing modes of decay.

Answer 38

False

Question 39

True or False: Beta particles emitted in radioactive decay are monoenergetic.

Answer 39

False

Question 40

True or False: A neutrino is a particle of negligible mass and zero charge postulated to account for the nonconservation of energy during beta decay.

Answer 40

True

Question 41

True or False: A neutrino is easy to detect.

Answer 41

False

Question 42

True or False: Mass is conserved in radioactive decay.

Answer 42

True

Question 43

Rn^222 is a _____.

Answer 43

Alpha emitter

Question 44

P^32 is a _____.

Answer 44

Pure beta emitter

Question 45

Ni^59 is a _____.

Answer 45

Electron capture radionuclide

Question 46

Sr^90 is a _____.

Answer 46

Beta emitter

Question 47

I^125 is a _____.

Answer 47

Electron capture radionuclide

Question 48

1.17 and 1.33 MeV gammas is _____.

Answer 48

Co^60

Question 49

0.662 MeV gamma is a _____.

Answer 49

Cs^137

Question 50

Several gammas of mean energy around 400 keV is _____.

Answer 50

Ir^192

Question 51

Several gammas of mean energy around 0.8 MeV is _____.

Answer 51

Rn^222

Question 52

Mean energy 28 keV is _____.

Answer 52

I^125

Question 53

What is the half life for Ra^226?

Answer 53

1626 years

Question 54

What is the half life for Cs^137?

Answer 54

30 years

Question 55

What is the half life of Ir^192

Answer 55

74 days

Question 56

What is the half life of Co^60?

Answer 56

5.26 years

Question 57

What is the half life of I^125?

Answer 57

59.6 days

Question 58

What is the mean life of Ir^192 source is give by _____ days.

Answer 58

106.5

Question 59

After two half lives, the initial activity of a given radioisotope would have reduced to _____.

Answer 59

One fourth of

Question 60

The mean life of a radioactive source is given by _____.

Answer 60

Question 61

The SI unit of activity is the _____.

Answer 61

Becquerel (Bq)

Question 62

One becquerel (Bq) corresponds to _____ nuclear transformations/second.

Answer 62

1

Question 63

One curie corresponds to _____.

Answer 63

37 GBq

Question 64

Isomeric transition is characterized by _____.

Answer 64

No change in the atomic or mass number

Question 65

The SI unit of radioactivity is the _____.

Answer 65

Becquerel (Bq)

Question 66

The half life of a free neutron is _____.

Answer 66

10.2 minutes

Question 67

What are true statements regarding the becquerel?

Answer 67

It is an SI unit for activity.
One Bq = 1 nuclear transformation per second
One Bq = (3.7 x 10^{10>)-1 Ci
It is named in honor of Henri Becquerel}

Question 68

Radionuclides are produced by irradiating the element in _____.

Answer 68

A nuclear reactor
A Linac
A cyclotron

Question 69

The Cs^137 radionuclide is _____.

Answer 69

A byproduct of fission in a reactor and hence is extracted from the spent fuel elements

Question 70

_____ nuclides have the same number of neutrons.

Answer 70

Isotones

Question 71

_____ nuclides have the same number of protons.

Answer 71

Isotopes

Question 72

_____ nuclides have the same mass number.

Answer 72

Isobars

Question 73

_____ nuclides have same Z, A but existing in different energy states.

Answer 73

Isomers

Question 74

The radioactive isotopes produced in a nuclear reactor _____.

Answer 74

Is neutron rich and decays emitting β^{- particles}

Question 75

This isotope has _____.

Answer 75

Has 77 protons
Has 115 neutrons

Question 76

A nuclides (Z, A) may transform into a nuclides (Z-1, A) by the emission of _____.

Answer 76

Question 77

Positron emission occurs in radionuclides that have an excess of _____.

Answer 77

Protons

Question 78

Of the following radionuclides, _____ are produced in accelerators.

Answer 78

Question 79

This change in atomic number represents: Z Z+1

Answer 79

β^-

Question 80

This change in atomic number represents: Z Z

Answer 80

Isomersim

Question 81

This change in atomic number represents: Z Z-1

Answer 81

Electron Capture
β⁺

Question 82

This change in atomic number represents: Z Z-2

Answer 82

α

Question 83

Method of radionuclide productivity: produced in a reactor by irradiating a stable element.

Answer 83

Ir^192

Question 84

Method of productivity: produced in a cyclotron.

Answer 84

Co^57

Question 85

Method of productivity: naturally occurring.

Answer 85

Ra^226

Question 86

Method of productivity: Eluted from a generator.

Answer 86

Tc^99m

Question 87

Method of productivity: separated from spent fuel element

Answer 87

I^131

Question 88

True or False regarding positron emission: each positron emission is accompanied by a neutrino.

Answer 88

True

Question 89

True or False regarding positron emission: a minimum of 1.02 MeV equivalent mass difference must exist between the parent and daughter atoms.

Answer 89

True

Question 90

True or False regarding positron emission: it is followed by two annihilation photons of energy 0.511 MeV each.

Answer 90

True

Question 91

True or False regarding positron emission: positrons are monoenergetic.

Answer 91

False

Question 92

True or False regarding electron capture (EC): it is a competing mode from which positron decay.

Answer 92

True

Question 93

True or False regarding electron capture (EC): when positron decay is energetically not possible, only EC can occur.

Answer 93

True

Question 94

True or False regarding electron capture (EC): it results in characteristic x-ray emission.

Answer 94

True

Question 95

True or False regarding electron capture (EC): it results in Auger electrons emission.

Answer 95

True

Question 96

True or False regarding electron capture (EC): it results in Auger electrons emission.

Answer 96

True

Question 97

True or False regarding electron capture (EC): it results in the emission of a neutrino.

Answer 97

True

Question 98

Characteristic x-rays are emitted following _____.

Answer 98

Internal conversion
Electron capture

Question 99

True or False - A radionuclide decaying by internal conversion emits: betas.

Answer 99

False

Question 100

True or False - A radionuclide decaying by internal conversion emits: gammas.

Answer 100

True

Question 101

True or False - A radionuclide decaying by internal conversion emits: characteristic x-rays.

Answer 101

True

Question 102

True or False - A radionuclide decaying by internal conversion emits: Auger electrons.

Answer 102

True

Question 103

True or False - During internal conversion: a beta is emitted.

Answer 103

False

Question 104

True or False - During internal conversion: there is no change in Z or A.

Answer 104

True

Question 105

True or False - During internal conversion: L and M shell electrons may also be emitted.

Answer 105

True

Question 106

True or False - During internal conversion: the shell electrons are ejected by the gamma ray emitted in the isomeric transition.

Answer 106

False

Question 107

True or False: X-rays are produced by decelerating high speed electrons in a target.

Answer 107

True

Question 108

True or False: the mechanism of x-ray production is the same in a kV x-ray unit and an accelerator unit.

Answer 108

False

Question 109

True or False: the major fraction of the electron energy is converted to x-rays.

Answer 109

False

Question 110

True or False: the x-ray spectrum produced is influenced by the thickness of the target.

Answer 110

True

Question 111

True or False: the x-rays produced would heat up the target.

Answer 111

False; the x-ray absorption in the target causes the heating up

Question 112

True or False: The electrons impinge on a large area of the target in a clinical accelerator.

Answer 112

False; they impinge on a small circle, about 3 mm

Question 113

True or False: Therapy x-ray beams used in the kV region are medium filtered.

Answer 113

True; they are not highly filtered, filtered medium to harden the beam by removing low-energy x-photons

Question 114

True or False: The beam quality of kilovoltage therapy x-ray beams can be adequately represented by the HVL.

Answer 114

False

Question 115

True or False: For the accelerator photon beams, AAPM TG-51 recommends TRP_{20/10 as the beam quality specifier.}

Answer 115

False; AAPM TG-51 recommends PDD (10, 10x10, SSD)_{X as beam quality specifier}

Question 116

True or False: The (Bremsstrahlung) X-ray spectrum produced in the target has a continuous spectrum.

Answer 116

True

Question 117

True or False: the maximum energy of the photons in the x-ray spectrum exceeds the energy of the electrons incident on the target.

Answer 117

False

Question 118

True or False: Characteristic x-rays are also produced in the target along with the continuous x-ray spectrum.

Answer 118

True

Question 119

True or False: the intensity of x-ray spectrum produced by a linear accelerator is maximum along the central axis of the beam and decreases considerably with increasing angle with respect to the central axis.

Answer 119

True

Question 120

The kV x-ray unit used in orthovoltage therapy must have a target _____.

Answer 120

Of high Z
Of high melting point

Question 121

The output of kilovoltage therapy unit is roughly proportional to _____.

Answer 121

Tube voltage kV^2
Z of target

Question 122

What distinguishes an x-ray photon from a gamma ray photon?

Answer 122

Origin

Question 123

True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: inelastic collision with electrons.

Answer 123

True

Question 124

True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: elastic collision with nuclei.

Answer 124

True

Question 125

True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: inelastic collision with nuclei.

Answer 125

True

Question 126

True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: elastic collision with neutron.

Answer 126

False

Question 127

True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: inelastic collision with proton.

Answer 127

False

Question 128

The Bremsstrahlung production probability for the target material varies as _____.

Answer 128

Z^2

Question 129

The efficiency of Bremsstrahlung production for the target material is proportional to _____.

Answer 129

Z E

Question 130

The maximum photon energy of the Bremsstrahlung spectrum is determined by the _____.

Answer 130

Maximum mA

Question 131

True or False - the Bremsstrahlung x-ray spectrum produced in a given x-ray target depends on: kinetic energy of the incident electron.

Answer 131

True

Question 132

True or False - the Bremsstrahlung x-ray spectrum produced in a given x-ray target depends on: binding energy of the electrons of the target atom.

Answer 132

False

Question 133

True or False - the Bremsstrahlung x-ray spectrum produced in a given x-ray target depends on: target Z.

Answer 133

True

Question 134

True or False - the Bremsstrahlung x-ray spectrum produced in a given x-ray target depends on: target thickness.

Answer 134

True

Question 135

This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV

Answer 135

100 kV

Question 136

This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV

Answer 136

400 kV

Question 137

This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV

Answer 137

4 MV

Question 138

This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV

Answer 138

20 MV

Question 139

True or False: Photons lose energy in small increments, thus gradually slowing down in the medium.

Answer 139

False; they either interact or they don’t

Question 140

True or False: Primary photons are the ones transmitted by and have not had any interaction with the medium traversed.

Answer 140

True

Question 141

True or False: Megavoltage photon interactions can release electrons of significant energy.

Answer 141

True

Question 142

True or False: Electrons are exponentially attenuated while traversing matter.

Answer 142

False

Question 143

True or False: Electrons do not produce Bremsstrahlung photons while interacting with matter.

Answer 143

False

Question 144

True or False: Electrons in their interactions can release secondary electrons of finite range.

Answer 144

True; they are called delta rays and they are partly responsible for the buildup exhibited by electron beam depth dose curves.

Question 145

True or False: Compton interactions are like billiard ball type collisions.

Answer 145

True

Question 146

True or False: All inelastic collisions of electrons with atomic electrons lead to ionization of atoms.

Answer 146

False

Question 147

True or False: A pencil beam of electrons incident on a foil spreads into a beam of larger cross-section due to multiple Coulombic interactions with nuclei of atoms.

Answer 147

True

Question 148

True or False: A narrow beam of photons incident on a foil spreads into a beam of larger cross-section due to multiple interactions with nuclei of atoms.

Answer 148

False

Question 149

True or False: High-energy electrons scatter more than low-energy electrons.

Answer 149

False

Question 150

True or False: High-energy electrons scatter more in high-Z materials.

Answer 150

True

Question 151

To produce an electron-position pair in the vicinity of a nucleus, the interacting photon must have a minimum energy of _____.

Answer 151

1.02 MeV

Question 152

To interact by photoelectric effect, the interacting photon’s energy must be _____.

Answer 152

Equal to or just greater than the binding energy of the electron

Question 153

To undergo a Compton effect, the energy of the interacting photon must be _____.

Answer 153

Much larger than the electron binding energy

Question 154

In photoelectric interaction, the photon loses _____.

Answer 154

All the energy

Question 155

In a Compton interaction, The photon loses _____.

Answer 155

Part of its energy

Question 156

The probability of Compton interaction (i.e., the electronic Compton coefficient) _____.

Answer 156

Decreases with an increase in photon energy

Question 157

As the photon energy increases, the Compton electron gets ejected _____.

Answer 157

More and more in the forward direction

Question 158

In the megavoltage energy range, the predominant interaction in a patient is _____/

Answer 158

Compton

Question 159

In the megavoltage energy range, the predominant interaction in a patient is _____.

Answer 159

Compton

Question 160

The probability of pair production (atomic cross section) in the interacting medium varies as _____.

Answer 160

Z^2

Question 161

The probability of photoelectric effect (atomic cross section) in a medium roughly varies as _____.

Answer 161

Z^3

Question 162

In pair production, after expending energy for the creation of the pair, the excess photon energy _____.

Answer 162

Is shared by the electron and positron

Question 163

As the photon energy increases, the probability of photoelectric effect roughly varies as _____.

Answer 163

1/E^3

Question 164

As the photon energy increases, the probability of photoelectric effect roughly varies as _____.

Answer 164

1/E³

Question 165

At the end of its range in the medium in pair production, the positron _____.

Answer 165

Is annihilated, resulting in two annihilation photons

Question 166

Photoelectric effect involves _____.

Answer 166

A bound electron

Question 167

A Compton interaction involves a photon interacting with _____.

Answer 167

A free electron

Question 168

Energy losses by electrons (in their collision interactions) are _____.

Answer 168

Dependent of Z

Question 169

Energy losses in radiative collisions, when electrons are stopped in medium, vary as _____.

Answer 169

Z^2

Question 170

The probability for photoelectric absorption is maximum when the gamma energy is _____.

Answer 170

Equal to the electron binding energy

Question 171

The threshold energy (in MeV) for pair production in the Coulombic Field of the nucleus is _____.

Answer 171

1.02

Question 172

The photoelectric cross-section _____.

Answer 172

Depends on both the photon energy and the atomic number of the medium

Question 173

Compton mass attenuation coefficient for a given gamma energy depends on _____.

Answer 173

The electron density of the medium

Question 174

Elastic scattering is characterized by _____.

Answer 174

Conservation of kinetic energy

Question 175

In Compton scattering, the energy of the incident photon _____.

Answer 175

Is equal to the energy of the scattered photon and the recoil electron (BE is negligible)

Question 176

The threshold energy in (MeV) for pair production in the vicinity of an electron is _____.

Answer 176

2.04

Question 177

The Compton (electronic) scattering cross-section depends on _____.

Answer 177

The gamma energy only

Question 178

The mass attenuation coefficient due to Compton interactions _____.

Answer 178

Decreases with energy and depends on electron density of medium

Question 179

For photoelectric absorption to take place, the gamma energy should be _____.

Answer 179

Exactly equal to or slightly larger than the electron binding energy

Question 180

True or False: When a photon traverses a medium, no interaction can occur.

Answer 180

True

Question 181

True or False: When a photon traverses a medium, complete absorption can occur.

Answer 181

True

Question 182

True or False: When a photon traverses a medium, scatter can occur.

Answer 182

True

Question 183

True or False: When an electron traverses a medium, no interaction can occur.

Answer 183

False

Question 184

True or False: When an electron traverses a medium, complete absorption in an inelastic collision can occur.

Answer 184

False

Question 185

True or False: When an electron traverses a medium, complete conversion into a Bremsstrahlung photon in a radiative collision can occur.

Answer 185

True

Question 186

In Compton scatter, the energy of the back-scattered photon (in MeV) is _____.

Answer 186

0.255

Question 187

The energy loss of electrons in water or tissue is roughly given (in MeV/cm) by _____.

Answer 187

2

Question 188

True or False: Multiple scattering of a pencil beam of electrons in a scattering foiled results in its angular spread.

Answer 188

True

Question 189

True or False: Multiple scattering of a pencil beam of electrons in a scattering foiled results in its energy degradation.

Answer 189

True

Question 190

True or False: Multiple scattering of a pencil beam of electrons in a scattering foiled results in Bremsstrahlung contamination.

Answer 190

True

Question 191

True or False: In a kV x-ray unit, the electrons are accelerated by a constant or pulsating positive DC potential.

Answer 191

True

Question 192

True or False: In an accelerator, the electrons are accelerated by an alternating AC voltage.

Answer 192

False

Question 193

True or False: In an accelerator the source of microwave energy is a klystron or a magnetron.

Answer 193

True

Question 194

True or False: In a microtron the electrons are accelerated in a straight path.

Answer 194

False

Question 195

True or False: Much of the electron energy deposited in the x-ray target reappears as heat.

Answer 195

True

Question 196

True or False: An efficient target cooling system is necessary in therapy machines

Answer 196

True

Question 197

True or False: A flattening filter is used in a Co^60 beam to produce a uniform (flat) beam profile.

Answer 197

False

Question 198

True or False: In a Co^60 unit the treatment time is controlled using a transmission monitor.

Answer 198

False

Question 199

True or False: there is no radiation from a Co^60 machine when the machine is switched off.

Answer 199

False

Question 200

True or False: There is no radiation from an accelerator when the machine is switched off.

Answer 200

True

Question 201

True or False: A Co^60 source is produced by irradiating a Co^59 cylinder for source dimensions in a nuclear reactor.

Answer 201

False

Question 202

True or False: The output of a Co^60 unit has to be measured only during source loading. The output on any treatment day can be determined using the exponential decay law.

Answer 202

False

Question 203

True or False: The kV x-ray beam used in radiation therapy is monoenergetic.

Answer 203

False

Question 204

True or False: The filter inserted in the beam path of a kV x-ray unit to preferentially absorb the soft components of the x-ray spectrum is known as the “inherent filtration.”

Answer 204

False

Question 205

True or False: If two fields have the same area, they will have the same equivalent square field.

Answer 205

False

Question 206

A flattening filter is used in an accelerator to _____.

A. Attenuate the clinical Photon beams and to reduce the beam output
B. change the spectra of the photon beam
C. Filter the low energy photons and to harden the beam
D. Get a flat beam profile at the clinical depth

Answer 206

D. Get a flat beam profile at the clinical depth

Question 207

The flattening filter used in a linear accelerator: (more than one answer may apply)

A. Makes the beam quality uniform across the field width
B. Hardens the beam more in the central region compared to the peripheral regions
C. Produces a horn in the cross-beam profile at shallower depths
D. Is cone shaped to attenuate more in the central region compared to the peripheral region

Answer 207

B. Hardens the beam more in the central region compared to the peripheral regions
C. Produces a horn in the cross-beam profile at shallower depths
D. Is cone shaped to attenuate more in the central region compared to the peripheral region

Question 208

The flattening filter position in the beam path is:

A. Immaterial
B. Critical
C. Not very critical

Answer 208

B. Critical

Question 209

Any error in the reproducible positioning of the flattening filter will affect: (more than one answer may apply)

A. Beam flatness
B. beam symmetry
C. beam output
D. None of the above

Answer 209

A. Beam flatness
B. beam symmetry
C. beam output

Question 210

An added filter used with a therapy kV unit:

A. Increases the output
B. “Softens” or reduces the effective energy of the beam
C. Achieves desired filtration for therapeutic purposes

Answer 210

C. Achieves desired filtration for therapeutic purposes

Question 211

The effective energy of an x-ray beam is the energy of that monoenergetic beam that would:

A. Give the same exposure rate at a reference distance as the x-ray beam in question
B. give the same HVL as the x-ray beam in question
C. Have the same inherent and added filtration in the beam path

Answer 211

B. give the same HVL as the x-ray beam in question

Question 212

The target of a therapy x-ray tube must have: (more than one answer may apply)

A. A high Z
B. A high melting point
C. Low thermal conductivity
D. Low specific heat

Answer 212

A. A high Z
B. A high melting point

Question 213

The efficiency of x-ray production in the kV x-ray therapy tubes is about:

A. 0.1%
B. 1%
C. 5%
D. 10%

Answer 213

B. 1%

Question 214

The focal spot of a kV s-ray therapy tube is about:

A. 1 mm
B. 3 mm
C. 10 mm

Answer 214

B. 3 mm

Question 215

The focal spot of a clinical linac is about:

A. 1 mm
B. 3 mm
C. 10 mm

Answer 215

B. 3 mm

Question 216

For a therapy x-ray unit operating at 150 kVp, the maximum energy (in keV) of the photon produced in the target is:

A. 150
B. <150
C. >150

Answer 216

A. 150

Question 217

The source of electrons in an electron accelerator is the:

A. Klystron
B. Accelerating waveguide
C. Electron gun
D. Magnetron

Answer 217

C. Electron gun

Question 218

Some important features of a linac compared to a Co^60 unit are: (more than one answer may apply)

A. Higher beam output
B. Sharper beam
C. Less maintenance cost
D. Less complex in design

Answer 218

A. Higher beam output
B. Sharper beam

Question 219

Modern accelerators can produce: (more than one answer may apply)

A. Asymmetric fields
B. Circular fields
C. Custom fields

Answer 219

A. Asymmetric fields

Question 220

A _____ target is used in a high-energy linear accelerator.

A. Transmission type
B. Reflection type
C. Refraction type

Answer 220

A. Transmission type

2nd Ed Medical Dosimetry Certification Study guide by K.N. Govinda Rajan, Ph.D.
A.
B.
C.
D.

Question 221

The skin sparing effect will be highest for _____.

A. A diagnostic x-ray beam
B. A orthovoltage x-ray beam
C. An electron beam
D. A megavoltage X-ray beam

Answer 221

D. A megavoltage x-ray beam

This is because of the long range of electrons produced by a photon beam.

2nd Ed Medical Dosimetry Certification Study guide by K.N. Govinda Rajan, Ph.D