Midterm Review

Question 1

what’s the mass defect of 23Na?
Z=11, a= 22.990
m(p)= 1.00727, m(n)= 1.00866

Answer 1

0.1939u

Question 2

how many atoms are in a gram of potassium-38?
Aw = 39.10
Na = 6.0221x10^23

Answer 2

1.540x10^22 atoms

Question 3

which force holds the nucleons together in the nucleus?

Answer 3

strong nuclear force

Question 4

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

Answer 4

D. it is impossible to know the exact position and momentum of an electron

Question 5

which of the following is a true statement regarding the Pauli Exclusion Principle?

Answer 5

more than one electron cannot be in the same quantum state at the same time

Question 6

what is the importance of the margic numbers with respect to nuclei?

Answer 6

nuclei with a magic number of neutrons and/or protons are more likely to be stable

Question 7

how many atoms in 4.0026 grams of heliuim?
Z=2. A=4, Aw= 4.0026
Na= 6.0221x10^23

Answer 7

6.0221x10^23

Question 8

T/F: every gram atomic weight of a substance contains the same number of atoms

Answer 8

true

Question 9

T/F: the highest electron binding energy is found in the electron shell closest to the nucleus

Answer 9

true

Question 10

for a radionuclide with a half-life of 15.7 years, what is the average life?

Answer 10

22.6 years

Question 11

the rate of disintegration of alarge number of radioactive atoms of a material is

Answer 11

the activity of the material

Question 12

a radionuclide has a decay constant of 0.00924/day. what is the half-life?

Answer 12

75 days

Question 13

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?

Answer 13

2.2 MBq

Question 14

what always happens when an atom goes through radioactive decay?

Answer 14

it becomes more stable

Question 15

the average life of cobalt-60 is 7.59 years. what is the half-life?

Answer 15

5.27 years

Question 16

iridiu-192 has a half-life of 74.3 days. the average life of iridium-192 is

Answer 16

107 days

Question 17

one becquerel is equal to

Answer 17

1 disintegration per second

Question 18

which type of radioactive decay only occurs with radionuclides with high atomic numbers?

Answer 18

alpha particle decay

Question 19

which type of radioactive decay is a precursor to annihilation radiaiton?

Answer 19

positron emission

Question 20

which type of radioactive decay can be modelled as a neutron converting to a proton in the nucleus?

Answer 20

beta minus decay

Question 21

which type of radioactive decay is often followed by the emission of a characteristic x-ray?

Answer 21

electron capture

Question 22

a nuclear reaction which releases additional energy in the reaction is known as

Answer 22

exoergic

Question 23

most stable nuclei have what combiniation of protons and neutrons?

Answer 23

even nmber of protons, even number of neutrons

Question 24

what is true regarding secular equilibrium?

Answer 24

the activity of the daugher radionuclide equals the activity of the parent radionuclide

Question 25

the process by which neutron interacts with a nucleus and the nucleus splits into two seperate nuclei is called

Answer 25

fission

Question 26

what is the A & Z for P?

Answer 26

A: 1 Z: 1

Question 27

what is the A & Z for N?

Answer 27

A: 1 Z: 0

Question 28

what is the A & Z for α?

Answer 28

A: 4 Z: 2

Question 29

which of the following types of generator has the lowest x-ray production efficiency?

Answer 29

single phase

Question 30

x-rays are created in an x-ray tube when the electrons strike the

Answer 30

target

Question 31

anodes are often made of copper because

Answer 31

copper performs as a good heat sink

Question 32

what is the fuction of diodes used in a voltage rectification circuit?

Answer 32

they only allow current to flow in one direction

Question 33

in the x-ray tube the electrons are created by the

Answer 33

filament

Question 34

the portion of the circuit which prevents electrons from traveling from the anode to the cathode is called

Answer 34

the voltage rectifier

Question 35

tungsten is a good x-ray target due to its

Answer 35

high atomic number high melting point high x-ray production

Question 36

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

Answer 36

D. all the above

Question 37

which is true regarding characterisitic x-rays?

Answer 37

they occur at discrete energies

Question 38

what is the efficiency of bremsstrahlung prodction for a tungsten target (Z= 74) and a beam of 200 kV electrons in percent?

Answer 38

1.3

Question 39

what is the efficiency of bremsstrahlung prodction for a tungsten target (Z=79) and a beam of 2.5 MV electrons in percent?

Answer 39

17.8

Question 40

which megavoltage unit would be best for dlivering a photon beam to two seperate rooms?

Answer 40

microtron

Question 41

what is the biggest disadvantage of a cobalt-60 teletherapy machine?

Answer 41

lower beam output

Question 42

which component of a linear accelerator injects the electrons into the accelerating tube?

Answer 42

electron gun

Question 43

in which component are the electrons given more energy ina modern linear accelerator?

Answer 43

accelerating tube

Question 44

which of the follwoing in NOT a function of the bending magnet of a linear accelerator?

Answer 44

flatten the electron field

Question 45

what are the functions of the bending magnet of a linear accelerator?

Answer 45

- focus the electron beam - guide the electron beam toward the xray target - refine the elctron enegery

Question 46

what is the correct order of the beam path for x-ray treatment in a linear accelerator?

Answer 46

x-ray target, primary collimator, flattening filter, ionization chamber

Question 47

calculate the penunra for | source size= 0.5, SDD=65, SSD= 100, d= 5

Answer 47

0.31

Question 48

which of the follwoing achines uses a radioactive material for treatment?

Answer 48

gamma knife

Question 49

which treatment machine rotates the x-ray beam around the patient similar to a CT scanner

Answer 49

tomotherapy

Question 50

geometric penumra improveswith increasing...

Answer 50

source to diaphram distance

Question 51

which heavy particle has a depth dose distribution similiar to cobalt-60?

Answer 51

neutron

Question 52

which of the follwoing is true about the Bragg Peak?

Answer 52

A. it give more dose at depth than at the surface B. the peak occurs where the proton energy is lowest C. both

Question 53

calculate how many atoms per gram there would be in pure aluminum. Z= 13, A=27 Aw= 26.982 Na= 6.0221 x10^23

Answer 53

2.232x10^22 atoms/g

Question 54

what is the binding energy for phosphorus? Z= 15, A=31, Aw= 30.97 Mp= 1.00727 Mn= 1.00866

Answer 54

258 MeV

Question 55

which force holds the nucleons together in the nucleus?

Answer 55

strong nuclear force

Question 56

for a radionuclide with a half-life of 15.7 years, the average life is

Answer 56

22.6 years

Question 57

One becquerel is equal to

Answer 57

1 dps

Question 58

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?

Answer 58

2.2 MBq

Question 59

the rate of disintegration of a large number of radioactive atoms of a material is

Answer 59

proportinal to the number of radioactive atoms present

Question 60

when the parent half-life is much, much great than the daughter half-life this is called

Answer 60

secular equilibrium

Question 61

what always happens when an atom goes through radioactive decay?

Answer 61

it becomes more stable

Question 62

for low Z material the stable elements have a nucleus with

Answer 62

an approximately equal number of protons and neutrons

Question 63

what type of radioactive decay can be modelled as a neutron converting to a proton in the nucleus?

Answer 63

beta minus decay

Question 64

most stable nuclei have what combination fo rpotons and neutrons?

Answer 64

even number of protons, even number of neutrons

Question 65

as the atomic number increases the ration of neutrons to protons in stable nuclei

Answer 65

ceomes increasingly greater than one

Question 66

which type of generator has the lowest efficiency?

Answer 66

single phase

Question 67

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

Answer 67

C. it is caused by the interaction of coulomb forces

Question 68

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

Answer 68

B. they occur at discrete energies

Question 69

the portion of the circuit which prevents electron from traveling from the anode to the cathode is called

Answer 69

the voltage rectifier

Question 70

in an x-ray tube the low voltage circuit causes the electrons to travel from the cathode to the anode

Answer 70

false

Question 71

tungsten is a good x-ray target due to

Answer 71

high melting point high x-ray production high atomic number

Question 72

copper is often used to make anodes because

Answer 72

copper performs as a good heat sink

Question 73

the area between the anode and cathode is known as the

Answer 73

high voltage

Question 74

anode is the _____ side and the cathode is the ______ side

Answer 74

positive | negative

Question 75

what is the source of the electrons

Answer 75

cathode