Midterm Review Flashcards
what’s the mass defect of 23Na?
Z=11, a= 22.990
m(p)= 1.00727, m(n)= 1.00866
0.1939u
how many atoms are in a gram of potassium-38?
Aw = 39.10
Na = 6.0221x10^23
1.540x10^22 atoms
which force holds the nucleons together in the nucleus?
strong nuclear force
which is true regarding the Heisenberg Uncertainty Principle?
A. the energy of a nucleus cannot be accurately measured
B. it is impossible to know the exact mass of a nucleus
C. none of the above
D. it is impossible to know the exact position and momentum of an electron
D. it is impossible to know the exact position and momentum of an electron
which of the following is a true statement regarding the Pauli Exclusion Principle?
more than one electron cannot be in the same quantum state at the same time
what is the importance of the margic numbers with respect to nuclei?
nuclei with a magic number of neutrons and/or protons are more likely to be stable
how many atoms in 4.0026 grams of heliuim?
Z=2. A=4, Aw= 4.0026
Na= 6.0221x10^23
6.0221x10^23
T/F: every gram atomic weight of a substance contains the same number of atoms
true
T/F: the highest electron binding energy is found in the electron shell closest to the nucleus
true
for a radionuclide with a half-life of 15.7 years, what is the average life?
22.6 years
the rate of disintegration of alarge number of radioactive atoms of a material is
the activity of the material
a radionuclide has a decay constant of 0.00924/day. what is the half-life?
75 days
if we start with 25 MBq of a radioactive material with a half-life of 27 days, how much will be left after 95 days?
2.2 MBq
what always happens when an atom goes through radioactive decay?
it becomes more stable
the average life of cobalt-60 is 7.59 years. what is the half-life?
5.27 years
iridiu-192 has a half-life of 74.3 days. the average life of iridium-192 is
107 days
one becquerel is equal to
1 disintegration per second
which type of radioactive decay only occurs with radionuclides with high atomic numbers?
alpha particle decay
which type of radioactive decay is a precursor to annihilation radiaiton?
positron emission
which type of radioactive decay can be modelled as a neutron converting to a proton in the nucleus?
beta minus decay
which type of radioactive decay is often followed by the emission of a characteristic x-ray?
electron capture
a nuclear reaction which releases additional energy in the reaction is known as
exoergic
most stable nuclei have what combiniation of protons and neutrons?
even nmber of protons, even number of neutrons
what is true regarding secular equilibrium?
the activity of the daugher radionuclide equals the activity of the parent radionuclide
the process by which neutron interacts with a nucleus and the nucleus splits into two seperate nuclei is called
fission
what is the A & Z for P?
A: 1
Z: 1
what is the A & Z for N?
A: 1
Z: 0
what is the A & Z for α?
A: 4
Z: 2
which of the following types of generator has the lowest x-ray production efficiency?
single phase
x-rays are created in an x-ray tube when the electrons strike the
target
anodes are often made of copper because
copper performs as a good heat sink
what is the fuction of diodes used in a voltage rectification circuit?
they only allow current to flow in one direction
in the x-ray tube the electrons are created by the
filament
the portion of the circuit which prevents electrons from traveling from the anode to the cathode is called
the voltage rectifier
tungsten is a good x-ray target due to its
high atomic number
high melting point
high x-ray production
which is true of bremsstrahlung radiation?]
A. the resultant x-ray can be varying energies
B. it is the primary source of x-rays from an x-ray tube
C. it is caused by the interaction of coulomb forces
D. all the above
D. all the above
which is true regarding characterisitic x-rays?
they occur at discrete energies
what is the efficiency of bremsstrahlung prodction for a tungsten target (Z= 74) and a beam of 200 kV electrons in percent?
1.3
what is the efficiency of bremsstrahlung prodction for a tungsten target (Z=79) and a beam of 2.5 MV electrons in percent?
17.8
which megavoltage unit would be best for dlivering a photon beam to two seperate rooms?
microtron
what is the biggest disadvantage of a cobalt-60 teletherapy machine?
lower beam output
which component of a linear accelerator injects the electrons into the accelerating tube?
electron gun
in which component are the electrons given more energy ina modern linear accelerator?
accelerating tube
which of the follwoing in NOT a function of the bending magnet of a linear accelerator?
flatten the electron field
what are the functions of the bending magnet of a linear accelerator?
- focus the electron beam
- guide the electron beam toward the xray target
- refine the elctron enegery
what is the correct order of the beam path for x-ray treatment in a linear accelerator?
x-ray target, primary collimator, flattening filter, ionization chamber
calculate the penunra for
source size= 0.5, SDD=65, SSD= 100, d= 5
0.31
which of the follwoing achines uses a radioactive material for treatment?
gamma knife
which treatment machine rotates the x-ray beam around the patient similar to a CT scanner
tomotherapy
geometric penumra improveswith increasing…
source to diaphram distance
which heavy particle has a depth dose distribution similiar to cobalt-60?
neutron
which of the follwoing is true about the Bragg Peak?
A. it give more dose at depth than at the surface
B. the peak occurs where the proton energy is lowest
C. both
calculate how many atoms per gram there would be in pure aluminum.
Z= 13, A=27 Aw= 26.982
Na= 6.0221 x10^23
2.232x10^22 atoms/g
what is the binding energy for phosphorus?
Z= 15, A=31, Aw= 30.97
Mp= 1.00727
Mn= 1.00866
258 MeV
which force holds the nucleons together in the nucleus?
strong nuclear force
for a radionuclide with a half-life of 15.7 years, the average life is
22.6 years
One becquerel is equal to
1 dps
if we start with 25 MBq of a radioactive material with a half-life of 27 days, how much will be left after 95 days?
2.2 MBq
the rate of disintegration of a large number of radioactive atoms of a material is
proportinal to the number of radioactive atoms present
when the parent half-life is much, much great than the daughter half-life this is called
secular equilibrium
what always happens when an atom goes through radioactive decay?
it becomes more stable
for low Z material the stable elements have a nucleus with
an approximately equal number of protons and neutrons
what type of radioactive decay can be modelled as a neutron converting to a proton in the nucleus?
beta minus decay
most stable nuclei have what combination fo rpotons and neutrons?
even number of protons, even number of neutrons
as the atomic number increases the ration of neutrons to protons in stable nuclei
ceomes increasingly greater than one
which type of generator has the lowest efficiency?
single phase
which is true of bremsstrahlung radiaiton?
A. the resultant x-ray enegery depends on the target material
B. it is the primary source of prtons from an x-ray tube
C. it is caused by the interaction of coulomb forces
D. all of the answers are true
C. it is caused by the interaction of coulomb forces
which is true regarding characteristic x-rays?
A. they are created through coulomb ineractions
B. they occur at discrete energies
C. they are the result of an electron moving to a higher electron shell
D. all fo the answers are correct
B. they occur at discrete energies
the portion of the circuit which prevents electron from traveling from the anode to the cathode is called
the voltage rectifier
in an x-ray tube the low voltage circuit causes the electrons to travel from the cathode to the anode
false
tungsten is a good x-ray target due to
high melting point
high x-ray production
high atomic number
copper is often used to make anodes because
copper performs as a good heat sink
the area between the anode and cathode is known as the
high voltage
anode is the _____ side and the cathode is the ______ side
positive
negative
what is the source of the electrons
cathode
