Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Rad Onc > Physics Basics > Flashcards

Physics Basics Flashcards

1
Q

What is the term to describe two atoms whose nuclei contain the same number of protons but different numbers of neutrons?

A

Isotopes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the term to describe two atoms whose nuclei contain the same number of neutrons but different numbers of protons?

A

Isotones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the term to describe two atoms whose nuclei contain the same number of nucleons but differ in their nuclear energy states?

A

Isomers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the mass of an amu (atomic mass unit)?

A

1/12 the mass of a C-12 atom = 1.66x10-27 “in between” weight of proton/neutron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an electron volt (eV)?

A

The kinetic energy acquired by an electron passing through a potential difference of 1V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the energy equivalent (E0) [E=mc2] of an electron at rest?

A

E0 = 0.511 MeV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the energy equivalent [E=mc2] of 1 amu?

A

931.5 MeV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Electrons can exist only in those orbits for which the angular momentum of the electron is an integral multiple of ____.

A

h/2π (h = Planck’s constant = 6.626x10-34 J-sec)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the maximum number of electrons in an orbit?

A

2(n2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are valence electrons?

A

Electrons in the outermost shell (lowest binding energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What impact does the Z of an atom have on the Coulomb forces/binding energy of electrons?

A

Higher Z = higher binding energy due to greater nuclear charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the four fundamental forces of nature, in order of strength?

A
  • Strong nuclear force (strongest)
  • Electromagnetic force
  • Weak nuclear force
  • Gravity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What equation describes the amount of energy carried in a photon?

A

E = hv (h = Planck’s constant = 6.626x10-34 J-sec)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

As the wavelength of a photon becomes shorter, what happens to frequency? Energy?

A

As wavelength shortens…

  • Frequency - higher
  • Energy - higher
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the A of an atom (i.e. I-131)? What is the Z of an atom?

A

A = mass number = number of nucleons Z = atomic number = number of protons **In a stable nucleus, A should = 2*(Z)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the Half Value Layer (HVL)? What equation describes this?

A

HVL = amount of material required to attenuate beam to 1/2(E0) HVL = [-ln(0.5)/u] where u(mu) is a constant of the material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is pair production? What is the threshold energy of the incident photon required for pair production to occur?

A

Pair production = photon passes close to nucleus, resulting in energy conversion into positron-electron pair Threshold energy = >/=1.022 MeV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the energy dissipated by an ionizing event?

A

~33eV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the difference between x-rays and gamma-rays?

A

x-rays produced extranuclearly, g-rays produced intranuclearly **otherwise identical in nature and properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where to x- and game-rays fall on the electromagnetic spectrum?

A

Short-wavelength end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are alpha particles?

A

Nuclei of helium atoms consisting of two protons and two neutrons with a net positive charge Can be produced by an accelerator or by decay of heavy nucleotides (i.e. uranium, radium)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which sources of radiation are directly ionizing? Indirectly ionizing?

A

charged particles - directly ionizing (sufficient kinetic energy to disrupt atomic structure of absorber) electromagnetic radiation - indirectly ionizing (when absorbed, give up energy produce fast-moving charged particles that produce damage)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the Compton process?

A

Incident photon strikes outer shell electron, ejecting the electron (transfer of kinetic energy) and diverting the path of the now lower energy incident photon (scattering)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Following a Compton interaction, is the wavelength of the scattered photon higher or lower than that of the incident photon?

A

lower (lower energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

An interaction proceeds as follows: an incident photon strikes an inner-shell electron, giving up all of its energy and resulting in ejection of the electron from its shell. What type interaction has just occurred?

A

Photoelectric effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

An interaction proceeds as follows: an incident photon strikes an inner-shell electron, giving up all of its energy (ie photoelectric effect) and resulting in ejection of the electron from its shell. What is the result of this ejection?

A
  • Electron from an outer shell “drops down” to fill the vacancy - Emission of characteristic x-rays by this transfer of energy
27
Q

The mass absorption coefficient for which of the following process varies based on Z: -Compton process -photoelectric effect

A

photoelectric effect

28
Q

What is a free radical?

A

atom/molecule with an unpaired orbital electron in the outer shell

29
Q

Which sources of radiation are directly ionizing? Indirectly ionizing?

A

charged particles - directly ionizing (sufficient kinetic energy to disrupt atomic structure of absorber) electromagnetic radiation - indirectly ionizing (when absorbed, give up energy produce fast-moving charged particles that produce damage)

30
Q

What is the Compton process?

A

Incident photon strikes outer shell electron, ejecting the electron (transfer of kinetic energy) and diverting the path of the now lower energy incident photon (scattering)

31
Q

What is the photoelectric effect?

A

Incident photon strikes inner shell electron and is entirely absorbed, providing sufficient energy to overcome binding energy and extra kinetic energy. The vacancy is immediately filled by an outer shell electron, producing characteristic x-rays

32
Q

Which of the following depends on the Z of the material? 1) Compton process 2) photoelectric effect

A

Photoelectric effect

33
Q

What equation describes the kinetic energy of an electron ejected through a photoelectric interaction?

A

hv - E(B) hv = energy of incident photon E(B) = binding energy of electron

34
Q

How does the mass absorption coefficient for photoelectric absorption correlate to Z?

A

appx Z^3

35
Q

A radioactive nuclide has Z > 82. How is this species most likely to decay?

A

Emission of alpha particle

36
Q

What is an alpha particle composed of?

A

2 protons, 2 neutrons (helium nucleus)

37
Q

A radioactive nuclide undergoes alpha decay. What impact does this have on the mass number (A) and atomic number (Z) of the atom?

A

A decreases by 4 (2 protons, 2 neutrons) Z decreases by 2 (2 protons)

38
Q

What is the general reaction for alpha decay?

A

(A,Z)X –> (A-4, Z-2)Y + (4,2)He + Q Q = disintegration energy, appears as kinetic energy of alpha particle and product nucleus

39
Q

What does the activity of a radioactive material describe?

A

Number of disintegrations per unit time =gN where gamma is the decay constant

40
Q

What units can be used to describe radioactive activity?

A

1 Bq = 1 disintegration per second 1 Ci = 3.7E10 Bq (1mCi = 3.7E7 Bq)

41
Q

Given the decay constant (g) for a radioactive nuclide, what is the half-life?

A

T1/2 = 0.693/g

42
Q

All elements with Z > ___ are radioactive.

A

Z > 82

43
Q

All naturally occurring radioactive elements can be grouped in to 3 series: uranium, actinium, and thorium. These series all terminate at stable isotopes of what element?

A

All terminate at stable isotopes of lead (A = 206, 207, and 208)

44
Q

What is the half-life of Co-60?

A

5.26yrs

45
Q

Co-60 emits two monoenergetic photons (g-rays) of what energy? Avg energy?

A

1.17 and 1.33 MeV Avg = 1.25 MeV

46
Q

What is the HVL (Pb) for 60-Co?

A

11mm Pb

47
Q

What is the half-life of Sr-90? Y-90?

A

28.9 yrs

48
Q

90-Sr emits ___ rays of what energy?

A

Beta-rays, 2.27MeV

49
Q

What is the physical half-life of 131-I? What else is needed to calculate the effective half-life?

A

T1/2 = 8d Biological half-life is required to calculate effective halflife 1/Teff = 1/Tphys + 1/Tbio

50
Q

What is the rest mass of a proton? A neutron?

E=mc2

A

Proton = 938 MeV

Neutron = 939 MeV

51
Q

What is the mass defect? What is the energy equivalent (E=mc2) of this value?

A

Mass difference between an atom and the sum of its constituent parts (ie, the energy required to form an atom)

Energy equivalent = binding energy of the nucleus

52
Q

What is the binding energy of an electron?

A

Minimum energy required to rip electron from atom

53
Q

As the number of protons in a given element increases to >20, what happens to the neutron:proton ratio?

A

Elements with Z>20 have a greater neutron:proton ratio

54
Q

What equation describes the decay constant (lambda)?

A

Lambda = Ln(2)
t1/2

=the probablility that a single nucleus within an element will undergo decay in a given time

*negative in exponential decay equation because probability decrease over time

55
Q

What is activity (A) and what are its units?

A

Activity = rate of decay

Unit = Bq (1 disintegration/sec)

1 Curie (Ci) = 3.7x1010 Bq

56
Q

What is the Emax of B-particles emitted from Sr-90?

A

2.27 MeV

57
Q

What is the half-life of Sr-90?

A

t1/2 = 28 years

58
Q

1 Ci = ??? Bq

A

1Ci = 3.7 x 1010 Bq

1Bq = 1 disintegration/sec

59
Q

How can the mean life (Ta) of a radioactive atom be determined?

A

Ta = 1.44 x t1/2

60
Q

In an element with a high n/p ratio (ie too many neutrons), what are the products of ß decay?

A

conversion of neutron –> proton

emission of electron (ß-/negatron), antineutrino, and Q (disintegration energy)

61
Q

What type of B decay results in emission of an antineutrino?

A

ß- decay

62
Q

What type of B decay occurs in an element with a low n/p ratio (ie too many protons)?

A

B+ decay

conversion of proton –> neutron

emission of B+, neutrino, and Q

Positron (B+) is inherently unstable and destined for annhilation event, thus ultimately emitting 2x0.511 MeV photons

63
Q

What nuclear processes can result in an element with an excess of protons?

A

Positron emission

Electron capture

64
Q

How is 99mTc produced?

A

99mTc has short t1/2 of 6hrs, so must be supplied as 99Mo

99Mo is supplied to hospitals after extraction from the neutron-irradiated uranium (235U) targets

Rad Onc (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions