Q 1-35

Question 1

The equivalent of 1 Sievert (Sv) is _____ rem.
A. 0.1
B. 1
C. 10
D. 100
E. 1000

Answer 1

D. 100

Question 2

Which of the following bowling ball arrangements describes a state with both zero kinetic energy
and nonzero mechanical potential energy?
A. suspended from a string from the ceiling
B. sitting still on the ground
C. rolling down the alley
D. striking stationary bowling pins
E. All of the above are true.

Answer 2

A. suspended from a string from the ceiling

Question 3

In an electromagnetic wave, the electric field and the magnetic field are oriented _____ apart from
one another.
A. 0º
B. 30º
C. 45º
D. 60º
E. 90º

Answer 3

E. 90º

Question 4

The ____ is the strongest force in the nucleus.
A. electromagnetic force
B. weak nuclear force
C. gravitational force
D. strong nuclear force
E. None of above is true.

Answer 4

D. strong nuclear force

Question 5

Iodine can be used as radiographic contrast because iodine _____.
A. is extremely dense and absorbs more photons than surrounding tissue
B. is radioactive and produces extra photons at the detector
C. has a k-edge just below the average energy of a diagnostic x-ray beam
D. generates more Compton scatter than soft tissue
E. None of the above is true.

Answer 5

C. has a k-edge just below the average energy of a diagnostic x-ray beam

Question 6

_____ decay is described by a radioactive emission resulting in a daughter atom whose atomic
number has increased by one and whose atomic mass number is unchanged from the parent.
A. β+
B. β–
C. α
D. Electron capture
E. Internal conversion

Answer 6

B. β–

Question 7

Alpha particle emission usually in occurs in atoms with _____.
A. substantially more protons than neutrons in the nucleus
B. substantially more protons than electrons in the atom
C. nuclei with an atomic number larger than 82
D. nuclei with an atomic number less than 82
E. None of the above is true.

Answer 7

C. nuclei with an atomic number larger than 82

Question 8

_____ can become radioactive immediately after a 15-MV linac x-ray beam is run for half an hour, e.g., for water tank scanning.

A. The water in the tank
B. The treatment room
C. The linac gantry head
D. The floor under the tank
E. None of the above is true.

Answer 8

C. The linac gantry head

Question 9

All of the following statements regarding x-ray production are true, EXCEPT which one?

A. X-rays are produced by two different mechanisms: bremsstrahlung and characteristic x-ray emission.
B. Characteristic x-rays have discrete energies.
C. Bremsstrahlung x-rays have a continuous spectrum of energies.
D. The efficiency of x-ray production is about 1% for a megavoltage linear accelerator.
E. The higher the energy of electrons bombarding the target, the more forward the direction of x-ray emission.

Answer 9

D. The efficiency of x-ray production is about 1% for a megavoltage linear accelerator.

Question 10

The quality of clinical beams in the superficial and orthovoltage range is described by _____.
A. kVp
B. mA-s
C. beam current
D. HVL
E. average energy

Answer 10

D. HVL

Question 11

A disadvantage of superficial x-rays compared to MeV electrons for radiotherapy is _____.
A. sharper penumbra
B. higher bone dose
C. less penetrating beam
D. All of the above are true.
E. None of the above is true.

Answer 11

B. higher bone dose

Question 12

A diagnostic x-ray tube and the electron gun in a linear accelerator both _____.

A. produce electrons that will hit an anode
B. have a thin beryllium window in the path of the output particles
C. generate electrons via thermionic emission
D. are affected by the heel effect
E. All of the above are true.

Answer 12

C. generate electrons via thermionic emission

Question 13

The anode surface in an x-ray tube that is struck by the electrons emitted by the cathode is called the _____.
A. focusing cup
B. heated filament
C. focal spot
D. exit window
E. tube housing

Answer 13

C. focal spot

Question 14

All of the following statements regarding 0.25-cm-wide versus 0.5-cm-wide MLC leaves are true, EXCEPT which one?

A. A 0.25-cm MLC can produce better conformality for small brain lesions.
B. A 0.25-cm MLC may limit the use of monoisocentric plans for large fields (e.g., breast tangents with supraclav field).
C. A 0.25-cm MLC will require a separate treatment planning system.
D. A 0.25-cm MLC can be used for IMRT and VMAT deliveries.
E. Dynamic wedges can be used regardless of MLC width.

Answer 14

C. A 0.25-cm MLC will require a separate treatment planning system.

Question 15

In an MV linac, defining 0º as the direction of the electron beam incident upon the target, the bremsstrahlung x-rays will be centered about which angle?
A. 0º
B. 45º
C. 90º
D. 180º
E. emission is isotropic

Answer 15

A. 0º

Question 16

The role of microwave energy in a linac is to _____.
A. liberate electrons
B. push electrons into the waveguide
C. accelerate electrons
D. select electrons with the correct energy
E. None of the above is true.

Answer 16

C. accelerate electrons

Question 17

A linac’s klystron is used to _____.

A. amplify microwaves
B. transport the microwaves to the accelerator
C. accelerate electrons
D. reflect microwaves to a water load
E. None of the above is true.

Answer 17

A. amplify microwaves

Question 18

List these linac components in the order that the beam would pass by or through them.
A. target; accelerating waveguide; bending magnets; flattening filter; collimator jaws
B. target; accelerating waveguide; collimator jaws; flattening filter; bending magnets
C. bending magnets; target; accelerating waveguide; collimator jaws; flattening filter
D. accelerating waveguide; collimator jaws; bending magnets; target; flattening filter
E. accelerating waveguide; bending magnets; target; flattening filter; collimator jaws

Answer 18

E. accelerating waveguide; bending magnets; target; flattening filter; collimator jaws

Question 19

The ion chambers of a linac monitor _____.

A. output
B. flatness
C. symmetry
D. All of the above are true.
E. None of the above is true.

Answer 19

D. All of the above are true.

Question 20

As the collimator setting decreases, photon backscatter into the monitor chamber _____.

A. increases
B. decreases
C. remains the same
D. There is not enough information given to answer this question.

Answer 20

A. increases

Question 21

The multi-leaf collimator (MLC) design feature for linear, unfocused leaves that keeps the resultant penumbra relatively constant for different leaf positions is _____.
A. their narrow leaf widths
B. their tongue-and-groove design
C. their rounded leaf ends
D. their tungsten material
E. None of the above is true.

Answer 21

C. their rounded leaf ends

Question 22

In a Compton scattering interaction, the incident photon _____ the attenuating media.
A. is absorbed by
B. is scattered by the nuclei of
C. is scattered by free or weakly bound electrons in
D. causes the emission of one or more nuclear particles in
E. produces new photons in

Answer 22

C. is scattered by free or weakly bound electrons in

Question 23

A _____ minimum thickness of graphite is needed to effectively block a 12-MeV electron beam, given that graphite (ρ = 2 g/cm^3) has an approximate total mass stopping power of 2 MeV cm^2/g.

A. 0.05 cm
B. 0.5 cm
C. 1.25 cm
D. 3.0 cm
E. 5.0 cm

Answer 23

D. 3.0 cm

Question 24

Calculate the linear attenuation coefficient (μ), given that a 2-mm thickness of material transmits 25% of a monoenergetic beam of photons.

A. –1 mm^–1
B. –0.693 mm^–1
C. 0.693 mm^–1
D. 1 mm^–1
E. 2 mm^–1

Answer 24

C. 0.693 mm^–1

Question 25

The most probable interaction/s of electrons with tissue in the clinical energy range is/are _____.
A. ionization and excitation
B. bremsstrahlung
C. elastic scattering
D. nuclear reaction
E. photodisintegration

Answer 25

A. ionization and excitation

Question 26

Bremsstrahlung x-ray production is most efficient at _____ electron energies and _____ atomic number targets.

A. high; high
B. low; low
C. high; low
D. low; high
E. Bremsstrahlung is not dependent on either electron energy or atomic number.

Answer 26

A. high; high

Question 27

An 80-keV photon will most likely undergo _____ in water.
A. coherent scattering
B. the photoelectric effect
C. Compton scattering
D. pair production
E. We are unable to determine this.

Answer 27

C. Compton scattering

Question 28

A 60-keV photon undergoes a photoelectric interaction with an atom having electron binding energies of 10 keV and 40 keV. What is the possible kinetic energy of the photoelectron?
A. 10 keV or 40 keV
B. 50 keV or 20 keV
C. 40 keV only
D. 30 keV only
E. 10 keV only

Answer 28

B. 50 keV or 20 keV

Question 29

In a photoelectric interaction, an incident photon transfers all of its energy to _____.
A. an electron from the electron shell of an atom within the medium
B. a free electron within the medium
C. the nucleus of an atom within the medium
D. the creation of an electron and positron within the medium
E. another photon incident upon the same medium

Answer 29

A. an electron from the electron shell of an atom within the medium

Question 30

Of the following, _____ is only defined in air.
A. kerma
B. exposure
C. absorbed dose
D. fluence
E. energy fluence

Answer 30

B. exposure

Question 31

The amount of photon energy crossing a unit area is defined as the _____ and the unit is _____.

A. energy fluence; MeV/cm2
B. energy fluence; MeV/(cm2 s)
C. kerma; J/Kg
D. dose; J/Kg
E. dose; MeV/cm2

Answer 31

A. energy fluence; MeV/cm2

Question 32

Charged particle equilibrium occurs when charged particles leaving a volume and charged particles entering the same volume have _____.

A. the same number of each type of particle at each specific energy
B. the same number of each type of particle, regardless of energy
C. the same number of particles, although the particle types may differ
D. the same total energy, regardless of whether the particle types are the same
E. the same total energy, regardless of whether the particle quantities are the same

Answer 32

A. the same number of each type of particle at each specific energy

Question 33

_____ is/are usually used for linear accelerator acceptance testing and commissioning.
A. Film
B. Survey meters
C. Ionization chambers
D. A water tank
E. All the above are true.

Answer 33

E. All the above are true.

Question 34

Of the following, _____ would be the most suitable for measuring CBCT dose on the linac.

A. a Farmer-type ionization chamber
B. a free air ionization chamber
C. optically stimulated luminescent dosimeters (OSLDs)
D. thermoluminescence dosimeters (TLDs)
E. radiochromic film

Answer 34

A. a Farmer-type ionization chamber

Question 35

The advantage of radiochromic film used in the MV photon range includes its _____.
A. insensitivity to ambient room light
B. minimal energy dependence
C. self-developing quality
D. nearly tissue-equivalent quality
E. All of the above are true.

Answer 35

E. All of the above are true.