NHR Atomic/Nucelar Structure From 2nd Ed MedDos Cert Study Guide By Rajan Flashcards
One atomic mass unit is equal to:
1.66 x 10^-27kg
From Review of Medical Dosimetry Book by William Amestoy
What is the conversion factor from MeV/c2
931
From Review of Medical Dosimetry Book by William Amestoy
What is the number of charge of a proton?
+1
From Review of Medical Dosimetry Book by William Amestoy
The nucleus of an atom is composed of_____.
Protons and Neutrons
From Review of Medical Dosimetry Book by William Amestoy
What is the force that binds electrons to the atom?
Electromagnetic force
From Review of Medical Dosimetry Book by William Amestoy
The energy needed to remove an electron from the shell is called_____.
Binding energy
From Review of Medical Dosimetry Book by William Amestoy
Electron binding energy increases _____.
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
The chemical properties of an atom are determined by:
Valence electrons
From Review of Medical Dosimetry Book by William Amestoy
The maximum number of electrons that can occupy a specific energy level is determined using the formula
2n2
From Review of Medical Dosimetry Book by William Amestoy
What is the maximum number of electrons that can hold in L shell?
8
From Review of Medical Dosimetry Book by William Amestoy
The atoms are designated by atomic symbols; the symbol A represents _____.
Mass number and number of protons and neutrons
From Review of Medical Dosimetry Book by William Amestoy
In a neutral atom, the number of electrons is equal to _____.
Atomic number
From Review of Medical Dosimetry Book by William Amestoy
The number of neutrons in an atom is equal to _____.
A - Z
From Review of Medical Dosimetry Book by William Amestoy
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:
79, 79, 118, 197, 79, 197
From Review of Medical Dosimetry Book by William Amestoy
The rest mass of an electron (MeV/c 2) is equal to:
0.511
From Review of Medical Dosimetry Book by William Amestoy
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
C. An electron moves from its original shell to another
From Review of Medical Dosimetry Book by William Amestoy
What is the maximum number of electrons allowed in M shell?
18
From Review of Medical Dosimetry Book by William Amestoy
An atom which is ionized and loses an electron is called a/an _____.
Positive ion
From Review of Medical Dosimetry Book by William Amestoy
Atoms who have nuclei with the same number of protons but different number of neutrons are called _____.
Isotopes
From Review of Medical Dosimetry Book by William Amestoy
This is a _____.
Isotone
From Review of Medical Dosimetry Book by William Amestoy
True or False: An alpha particle is identical to a helium nucleus with a mass number of 4 and an electrostatic charge of +2.
True
True or False: Alpha particles are usually emitted by low-Z radioactive elements during radioactive decay.
False
True or False: Alpha emission changes the identity of the radionuclide.
True
True or False: Ra^226 is an alpha emitter.
True
True or False: Co^60 is an alpha emitter.
False
True or False: A beta particle is an electron emitted by the atomic nucleus during a radioactive decay.
True
True or False: Co^60 is a beta emitter.
True
True or False: Ir^192 is a beta emitter.
True
True or False: Emission of beta changes the identity of the radionuclide.
True
True or False: A positron is a positively charged particle but identical to an electron in all other respects.
True
Note: the reference says they are practically identical, which to me means it can be argued to be False
True or False: Beta decay is usually associated with proton rich radionuclides.
False
True or False: Positron decay is usually associated with neutron rich radionuclides.
False
True or False: Emission of gamma radiation does not change the identity of the radionuclide.
True
True or False: Gamma usually follows beta particle emission in radioactive decay.
True
True or False: There are no pure beta emitters.
False
True or False: There are no pure gamma emitters.
False
True or False: Electron capture usually occurs in high-Z radioactive elements.
True
True or False: Electron capture and beta emission are competing modes of decay.
False
True or False: Beta particles emitted in radioactive decay are monoenergetic.
False
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.
True
True or False: A neutrino is easy to detect.
False
True or False: Mass is conserved in radioactive decay.
True
Rn^222 is a _____.
Alpha emitter
P^32 is a _____.
Pure beta emitter
Ni^59 is a _____.
Electron capture radionuclide
Sr^90 is a _____.
Beta emitter
I^125 is a _____.
Electron capture radionuclide
1.17 and 1.33 MeV gammas is _____.
Co^60
0.662 MeV gamma is a _____.
Cs^137
Several gammas of mean energy around 400 keV is _____.
Ir^192
Several gammas of mean energy around 0.8 MeV is _____.
Rn^222
Mean energy 28 keV is _____.
I^125
What is the half life for Ra^226?
1626 years
What is the half life for Cs^137?
30 years
What is the half life of Ir^192
74 days
What is the half life of Co^60?
5.26 years
What is the half life of I^125?
59.6 days
What is the mean life of Ir^192 source is give by _____ days.
106.5
After two half lives, the initial activity of a given radioisotope would have reduced to _____.
One fourth of
The mean life of a radioactive source is given by _____.
The SI unit of activity is the _____.
Becquerel (Bq)
One becquerel (Bq) corresponds to _____ nuclear transformations/second.
1
One curie corresponds to _____.
37 GBq
Isomeric transition is characterized by _____.
No change in the atomic or mass number
The SI unit of radioactivity is the _____.
Becquerel (Bq)
The half life of a free neutron is _____.
10.2 minutes
What are true statements regarding the becquerel?
It is an SI unit for activity.
One Bq = 1 nuclear transformation per second
One Bq = (3.7 x 1010>)-1 Ci
It is named in honor of Henri Becquerel
Radionuclides are produced by irradiating the element in _____.
A nuclear reactor
A Linac
A cyclotron
The Cs^137 radionuclide is _____.
A byproduct of fission in a reactor and hence is extracted from the spent fuel elements
_____ nuclides have the same number of neutrons.
Isotones
_____ nuclides have the same number of protons.
Isotopes
_____ nuclides have the same mass number.
Isobars
_____ nuclides have same Z, A but existing in different energy states.
Isomers
The radioactive isotopes produced in a nuclear reactor _____.
Is neutron rich and decays emitting β- particles
This isotope has _____.
Has 77 protons
Has 115 neutrons
A nuclides (Z, A) may transform into a nuclides (Z-1, A) by the emission of _____.
Positron emission occurs in radionuclides that have an excess of _____.
Protons
Of the following radionuclides, _____ are produced in accelerators.
This change in atomic number represents: Z Z+1
β-
This change in atomic number represents: Z Z
Isomersim
This change in atomic number represents: Z Z-1
Electron Capture
β+
This change in atomic number represents: Z Z-2
α
Method of radionuclide productivity: produced in a reactor by irradiating a stable element.
Ir^192
Method of productivity: produced in a cyclotron.
Co^57
Method of productivity: naturally occurring.
Ra^226
Method of productivity: Eluted from a generator.
Tc^99m
Method of productivity: separated from spent fuel element
I^131
True or False regarding positron emission: each positron emission is accompanied by a neutrino.
True
True or False regarding positron emission: a minimum of 1.02 MeV equivalent mass difference must exist between the parent and daughter atoms.
True
True or False regarding positron emission: it is followed by two annihilation photons of energy 0.511 MeV each.
True
True or False regarding positron emission: positrons are monoenergetic.
False
True or False regarding electron capture (EC): it is a competing mode from which positron decay.
True
True or False regarding electron capture (EC): when positron decay is energetically not possible, only EC can occur.
True
True or False regarding electron capture (EC): it results in characteristic x-ray emission.
True
True or False regarding electron capture (EC): it results in Auger electrons emission.
True
True or False regarding electron capture (EC): it results in Auger electrons emission.
True
True or False regarding electron capture (EC): it results in the emission of a neutrino.
True
Characteristic x-rays are emitted following _____.
Internal conversion
Electron capture
True or False - A radionuclide decaying by internal conversion emits: betas.
False
True or False - A radionuclide decaying by internal conversion emits: gammas.
True
True or False - A radionuclide decaying by internal conversion emits: characteristic x-rays.
True
True or False - A radionuclide decaying by internal conversion emits: Auger electrons.
True
True or False - During internal conversion: a beta is emitted.
False
True or False - During internal conversion: there is no change in Z or A.
True
True or False - During internal conversion: L and M shell electrons may also be emitted.
True
True or False - During internal conversion: the shell electrons are ejected by the gamma ray emitted in the isomeric transition.
False
True or False: X-rays are produced by decelerating high speed electrons in a target.
True
True or False: the mechanism of x-ray production is the same in a kV x-ray unit and an accelerator unit.
False
True or False: the major fraction of the electron energy is converted to x-rays.
False
True or False: the x-ray spectrum produced is influenced by the thickness of the target.
True
True or False: the x-rays produced would heat up the target.
False; the x-ray absorption in the target causes the heating up
True or False: The electrons impinge on a large area of the target in a clinical accelerator.
False; they impinge on a small circle, about 3 mm
True or False: Therapy x-ray beams used in the kV region are medium filtered.
True; they are not highly filtered, filtered medium to harden the beam by removing low-energy x-photons
True or False: The beam quality of kilovoltage therapy x-ray beams can be adequately represented by the HVL.
False
True or False: For the accelerator photon beams, AAPM TG-51 recommends TRP20/10 as the beam quality specifier.
False; AAPM TG-51 recommends PDD (10, 10x10, SSD)X as beam quality specifier
True or False: The (Bremsstrahlung) X-ray spectrum produced in the target has a continuous spectrum.
True
True or False: the maximum energy of the photons in the x-ray spectrum exceeds the energy of the electrons incident on the target.
False
True or False: Characteristic x-rays are also produced in the target along with the continuous x-ray spectrum.
True
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.
True
The kV x-ray unit used in orthovoltage therapy must have a target _____.
Of high Z
Of high melting point
The output of kilovoltage therapy unit is roughly proportional to _____.
Tube voltage kV^2
Z of target
What distinguishes an x-ray photon from a gamma ray photon?
Origin
True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: inelastic collision with electrons.
True
True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: elastic collision with nuclei.
True
True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: inelastic collision with nuclei.
True
True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: elastic collision with neutron.
False
True or False - When a high-energy electron (in the MeV range) collides with a target this interaction can occur: inelastic collision with proton.
False
The Bremsstrahlung production probability for the target material varies as _____.
Z^2
The efficiency of Bremsstrahlung production for the target material is proportional to _____.
Z E
The maximum photon energy of the Bremsstrahlung spectrum is determined by the _____.
Maximum mA
True or False - the Bremsstrahlung x-ray spectrum produced in a given x-ray target depends on: kinetic energy of the incident electron.
True
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.
False
True or False - the Bremsstrahlung x-ray spectrum produced in a given x-ray target depends on: target Z.
True
True or False - the Bremsstrahlung x-ray spectrum produced in a given x-ray target depends on: target thickness.
True
This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV
100 kV
This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV
400 kV
This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV
4 MV
This figure 2 shows the x-ray spectrum produced by the electron beam of _____ energy?
4 MV, 20 MV, 100 kV, or 400 kV
20 MV
True or False: Photons lose energy in small increments, thus gradually slowing down in the medium.
False; they either interact or they don’t
True or False: Primary photons are the ones transmitted by and have not had any interaction with the medium traversed.
True
True or False: Megavoltage photon interactions can release electrons of significant energy.
True
True or False: Electrons are exponentially attenuated while traversing matter.
False
True or False: Electrons do not produce Bremsstrahlung photons while interacting with matter.
False
True or False: Electrons in their interactions can release secondary electrons of finite range.
True; they are called delta rays and they are partly responsible for the buildup exhibited by electron beam depth dose curves.
True or False: Compton interactions are like billiard ball type collisions.
True
True or False: All inelastic collisions of electrons with atomic electrons lead to ionization of atoms.
False
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.
True
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.
False
True or False: High-energy electrons scatter more than low-energy electrons.
False
True or False: High-energy electrons scatter more in high-Z materials.
True
To produce an electron-position pair in the vicinity of a nucleus, the interacting photon must have a minimum energy of _____.
1.02 MeV
To interact by photoelectric effect, the interacting photon’s energy must be _____.
Equal to or just greater than the binding energy of the electron
To undergo a Compton effect, the energy of the interacting photon must be _____.
Much larger than the electron binding energy
In photoelectric interaction, the photon loses _____.
All the energy
In a Compton interaction, The photon loses _____.
Part of its energy
The probability of Compton interaction (i.e., the electronic Compton coefficient) _____.
Decreases with an increase in photon energy
As the photon energy increases, the Compton electron gets ejected _____.
More and more in the forward direction
In the megavoltage energy range, the predominant interaction in a patient is _____/
Compton
In the megavoltage energy range, the predominant interaction in a patient is _____.
Compton
The probability of pair production (atomic cross section) in the interacting medium varies as _____.
Z^2
The probability of photoelectric effect (atomic cross section) in a medium roughly varies as _____.
Z^3
In pair production, after expending energy for the creation of the pair, the excess photon energy _____.
Is shared by the electron and positron
As the photon energy increases, the probability of photoelectric effect roughly varies as _____.
1/E^3
As the photon energy increases, the probability of photoelectric effect roughly varies as _____.
1/E3
At the end of its range in the medium in pair production, the positron _____.
Is annihilated, resulting in two annihilation photons
Photoelectric effect involves _____.
A bound electron
A Compton interaction involves a photon interacting with _____.
A free electron
Energy losses by electrons (in their collision interactions) are _____.
Dependent of Z
Energy losses in radiative collisions, when electrons are stopped in medium, vary as _____.
Z^2
The probability for photoelectric absorption is maximum when the gamma energy is _____.
Equal to the electron binding energy
The threshold energy (in MeV) for pair production in the Coulombic Field of the nucleus is _____.
1.02
The photoelectric cross-section _____.
Depends on both the photon energy and the atomic number of the medium
Compton mass attenuation coefficient for a given gamma energy depends on _____.
The electron density of the medium
Elastic scattering is characterized by _____.
Conservation of kinetic energy
In Compton scattering, the energy of the incident photon _____.
Is equal to the energy of the scattered photon and the recoil electron (BE is negligible)
The threshold energy in (MeV) for pair production in the vicinity of an electron is _____.
2.04
The Compton (electronic) scattering cross-section depends on _____.
The gamma energy only
The mass attenuation coefficient due to Compton interactions _____.
Decreases with energy and depends on electron density of medium
For photoelectric absorption to take place, the gamma energy should be _____.
Exactly equal to or slightly larger than the electron binding energy
True or False: When a photon traverses a medium, no interaction can occur.
True
True or False: When a photon traverses a medium, complete absorption can occur.
True
True or False: When a photon traverses a medium, scatter can occur.
True
True or False: When an electron traverses a medium, no interaction can occur.
False
True or False: When an electron traverses a medium, complete absorption in an inelastic collision can occur.
False
True or False: When an electron traverses a medium, complete conversion into a Bremsstrahlung photon in a radiative collision can occur.
True
In Compton scatter, the energy of the back-scattered photon (in MeV) is _____.
0.255
The energy loss of electrons in water or tissue is roughly given (in MeV/cm) by _____.
2
True or False: Multiple scattering of a pencil beam of electrons in a scattering foiled results in its angular spread.
True
True or False: Multiple scattering of a pencil beam of electrons in a scattering foiled results in its energy degradation.
True
True or False: Multiple scattering of a pencil beam of electrons in a scattering foiled results in Bremsstrahlung contamination.
True
True or False: In a kV x-ray unit, the electrons are accelerated by a constant or pulsating positive DC potential.
True
True or False: In an accelerator, the electrons are accelerated by an alternating AC voltage.
False
True or False: In an accelerator the source of microwave energy is a klystron or a magnetron.
True
True or False: In a microtron the electrons are accelerated in a straight path.
False
True or False: Much of the electron energy deposited in the x-ray target reappears as heat.
True
True or False: An efficient target cooling system is necessary in therapy machines
True
True or False: A flattening filter is used in a Co^60 beam to produce a uniform (flat) beam profile.
False
True or False: In a Co^60 unit the treatment time is controlled using a transmission monitor.
False
True or False: there is no radiation from a Co^60 machine when the machine is switched off.
False
True or False: There is no radiation from an accelerator when the machine is switched off.
True
True or False: A Co^60 source is produced by irradiating a Co^59 cylinder for source dimensions in a nuclear reactor.
False
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.
False
True or False: The kV x-ray beam used in radiation therapy is monoenergetic.
False
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.”
False
True or False: If two fields have the same area, they will have the same equivalent square field.
False
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
D. Get a flat beam profile at the clinical depth
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
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
The flattening filter position in the beam path is:
A. Immaterial
B. Critical
C. Not very critical
B. Critical
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
A. Beam flatness
B. beam symmetry
C. beam output
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
C. Achieves desired filtration for therapeutic purposes
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
B. give the same HVL as the x-ray beam in question
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
A. A high Z
B. A high melting point
The efficiency of x-ray production in the kV x-ray therapy tubes is about:
A. 0.1%
B. 1%
C. 5%
D. 10%
B. 1%
The focal spot of a kV s-ray therapy tube is about:
A. 1 mm
B. 3 mm
C. 10 mm
B. 3 mm
The focal spot of a clinical linac is about:
A. 1 mm
B. 3 mm
C. 10 mm
B. 3 mm
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
A. 150
The source of electrons in an electron accelerator is the:
A. Klystron
B. Accelerating waveguide
C. Electron gun
D. Magnetron
C. Electron gun
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
A. Higher beam output
B. Sharper beam
Modern accelerators can produce: (more than one answer may apply)
A. Asymmetric fields
B. Circular fields
C. Custom fields
A. Asymmetric fields
A _____ target is used in a high-energy linear accelerator.
A. Transmission type
B. Reflection type
C. Refraction type
A. Transmission type
2nd Ed Medical Dosimetry Certification Study guide by K.N. Govinda Rajan, Ph.D.
A.
B.
C.
D.
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
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
