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RAD 380 - Physics of Radiation Therapy > Test 1 > Flashcards

Flashcards in Test 1 Deck (175):
1

Kilo- (k)

1000 units (10^3)

2

Hecto- (h)

100 units

3

Deka- (da)

10 units

4

Deci- (d)

0.1 units

5

Centi- (c)

0.01 units (10^-2)

6

Milli- (m)

0.001 units (10^-3)

7

Mega- (M)

1,000,000 units (10^6)

8

Speed of light

3 x 10^8 m/s

9

3 subatomic particles

Neutrons
Electrons
Protons

10

Neutrons and protons inside the nucleus

Nucleons

11

2 nucleons

Neutrons
Protons

12

Radius of the nucleus

10^-15 m

13

Radius of the electronic orbit of electrons around the nucleus

10^-10 m

14

The nucleus orbit is _______ than the electron orbit

Smaller

15

The mass of a nucleon is about _______ times that of an electron

2,000

16

A theory of atomic structure in which an atom is assumed to consist of protons as nucleons in the nucleus, with electrons moving in distinct circular orbits around it, each orbit corresponding to a specific quantized energy state

Bohr's model

17

Max number of electrons in each respective shell

2n^2

18

Electrons closer to the nucleus have ________ binding energy

Higher

19

Number of protons

Atomic number (Z)

20

Number of nucleons

Atomic mass number (A) (amus)

21

Formula for the number of neutrons

N=A-Z

22

How is the chemical identity of an element determined?

By the number of protons in the nucleus

23

What determines an element's chemical behavior?

The number of electrons

24

Two atomic nuclei with the same atomic number/Z/number of protons but a different number of neutrons

Isotope

25

Same number of neutrons but different atomic number (Z)

Isotone

26

Same mass number/number of nucleons (protons + neutrons)/A, but different atomic number/number of protons/Z

Isobar

27

Same mass number/number of nucleons/A, but in a different nuclear state (metastable state/different energy level = excited state)

Isomer

28

Every gram atomic weight of a substance contains ______ number of atoms

The same

29

Avagadro's number (NA)

6.0221 x 10^23 atoms per gram atomic weight (mole) or electrons/gram

30

Atomic mass unit

amu

31

1 amu = how many kg or Mev

1.66 x 10^-27
931.4 MeV

32

Formula to find the number of atoms per gram for an element

Avagadro's number (NA)/atomic weight (AW)
6.0221 x 10^23 atoms/gram / AW

33

1 amu is equal to what of a Carbon-12 atom?

1/12 of a Carbon-12 atom

34

When subatomic particles join together to form an atom it takes energy to do so; the subatomic particles give up some of their mass to be converted to attain this necessary energy to hold the particles together
Difference of the mass of an element versus the mass of all subatomic particles in that particular atom

Mass defect

35

Amount of energy required to remove an electron from the atom

Binding energy

36

Mass of a proton

1.00727 amu

37

Mass of a neutron

1.00866 amu

38

Mass of an electron

0.000548 amu

39

Formula for mass defect

Atomic mass number - ((# of P+ * 1.00727) + (# of N * 1.00866) + (# of E- * (0.000548))

40

Einstein's Theory of Relativity

Energy (E) = mass (m) * speed of light (C)^2

41

kgm^2/s^2

Joules (J)

42

1 eV = how many J?

1.60218 x 10^-19 J

43

5 steps to find binding energy

Find the mass defect (amu)
Convert it to kilograms (kg)
Find the energy converted (E=mc^2)
Convert to eV
Convert to megaelectronvolts (MeV)

44

Formula for converting mass defect (amu) to kg

Mass defect (amu) x (1.66 x 10^-27 kg/1 amu) = kg

45

Formula for converting energy (J) to eV

eV = J/1.602x10^-19 eV

46

Formula for converting eV to MeV

MeV = eV/1,000,000

47

Basic unit of energy

Joule (J)

48

1 J/kg = ? Rads = ? Gy

1 J/kg = 100 Rads = 1 Gy

49

100 cGy = ? Gy

100 cGy = 1 Gy

50

1 cGy = ? rad = ? Gy

1 cGy = 1 rad = 0.01 Gy

51

Combination of two lighter nuclei that takes energy to put them together; low mass nuclei are combined to produce a larger nucleus
Nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy
If light energy could combine, the average binding energy of the resulting nucleus would be greater, leaving excess energy to be released
Occurs in nature
Fuse two small particles to make a big one

Nuclear fusion

52

Nucleus with an atomic number greater than 56 splits into two smaller nuclei and have a higher binding energy per nucleon and therefore energy is released (ex: atomic bomb or Uranium Nuclear Reactors split atoms to give off energy)
Occurs when high Z nuclei are bombarded by neutrons; after absorbing the neutrons, it splits into nuclei of lower Z, as well as more neutrons
Ex: (235/92)U + (1/0)n --> (236/92)U --> (141/56)Ba + (3)(1/0)n + Q (energy)

Nuclear fission

53

As nature attempts to balance forces, spontaneous transformation of a nucleus into a lower binding energy occurs
This larger nucleus breaks into two or more parts that can be radioactive themselves (alpha particles, beta, etc.); excess energy is released as gamma rays and a new product called the daughter is more tightly bound (higher binding energy)
Nature attempts to minimize energy/make it as negative as possible by transforming one nucleus into another with lower (more negative) binding energy; this excess energy is released as radiation
Nuclei are breaking apart to become stable

Radioactive decay

54

Resulting nucleus of radioactive decay that is more tightly bound
Some radioactive substances break down and give rise to a radioactive product

Daughter

55

Nuclei that do not undergo radioactive decay

Stable

56

Wave model (energy)

C=vλ

C=velocity
v=frequency (Hz or 1/sec)
λ=wavelength

57

Describes the relationship between energy and frequency (λ)

Plank's constant

58

Graphs binding energy per nucleon vs. atomic number

Curve of binding energy (BE)

59

Average binding energy (BE) of most nuclei

8 MeV per nucleon

60

BE per nucleon reaches peak with what element?

Iron (Fe56)

61

Excess energy is released from radioactive decay as this

Gamma rays

62

Too many protons make the nucleus _______

Unstable

63

Ratio of neutrons to protons

1.4 neutrons for 1 proton

64

A material composed of the antiparticle "partners" to the corresponding particles of ordinary matter
A particle and its antiparticle have the same mass as one another, but opposite electric charge and other quantum numbers

Antimatter

65

Particle with equal mass and magnitude to an electron but opposite sign of charge (+)

Postiron (e+)
Anti-electron

66

Every particle has an ______

Antiparticle

67

When positron meets electron, they disappear, leaving behind to gamma ray photons that travel in opposite directions
This is an example of the complete conservation of matter into energy as described by Einstein's equation E=mc^2
Charge is conserved because the net charge both before and after is zero

Annihilation reaction
e+ +e- = 2y

68

What is the energy of each gamma ray emitted during annihilation reaction?

0.511 MeV

69

Gamma radiation emitted during annihilation reaction

Annihilation radiation

70

The total energy of the two gamma photons emitted during annihilation reaction is equal to what?

The rest mass energy of the positron plus electron

71

What is common radiation therapy doses (Gy)?

1.8-2 Gy

72

Plank's constant formula (to find wavelength given energy)

E =hc/λ

E = energy (J)
h = Plank's constant = 6.62 x 10^-34 J-sec
c = speed of light = 3x10^ 8 m/s
λ = wavelength (m) = usually a small number with an exponent at -14 to -15 range

73

Plank's constant number (h)

6.62 x 10^-34 J-sec

74

Frequency formula (wave + quantum model)

V = c/λ

V = frequency (1/s or Hz)
c = speed of light = 3x10^ 8 m/s
λ = wavelength (m) from Plank's constant formula

75

Electron density formula

Number of electrons/grams = (NA x Z)/Aw

NA = 6.0221 x 10^23 atoms/g
Z = atomic number/number of protons
Aw = atomic weight/protons + neutrons

76

What is the difference between kVp versus keV/MeV?

kVp infers there is a spectrum (highest energy) made from Brems interactions/manmade x-ray that is usually 1/3 of the beam = manmade
keV/MeV is a monoenergetic beam that is naturally occurring from radioactive decay

77

931.4 MeV = ? amu

1 amu

78

Number of constituent particles in atoms or molecules, contained in one mole
Ratio of molar mass of a compound to that of the mass of a sample (Carbon-12)
Has a reciprocal dimension

Avagadro's constant

79

Amount of substance that contains as many atoms as there are atoms in 12 grams of Carbon-12

Mole

80

Number of atoms in 12 grams of Carbon-12
Dimensionless quantity
12 grams of Carbon-12 has 6.022 x 10^23 carbon atoms

Avagadro's number (NA)

81

Phenomenon where radiation is given off in the form of particles or electromagnet waves; atom is attempting to become stable

Radioactivity

82

2 forms of radioactivity

Particle form
Electromagnetic

83

2 particle forms of radioactivity

Alpha (a)
Beta (B- or +)

84

2 beta particles

Electrons (B-)
Positrons (B+)

85

Helium nuclei
4/2He^2+ (2 protons, 2 neutrons, 0 electrons)
Travel a short distance in matter

Alpha (a) particles

86

Gamma (y) rays, same as x-rays only originating from the nucleus
High energy photons (neutral)
Any photons emitted by nuclei or in electron-positron annihilation
Monoenergetic because it is naturally occurring (keV); specific energy

Electromagnetic radiation from radioactivity

87

All elements with Z greater than what are radioactive/unstable?

82 (lead)
Bismuth 83

88

Potential to decay, energy in an atom
Rate of decay; disintegrations per unit of time

Activity

89

Activity formula

At=Aoe^-λt

At = activity after time
Ao= original activity
t = time elapsed
λ = decay constant (ln2/T^1/2)

90

Amount of time for radioactive substance to decay to half its original activity or to decay to half the number of radioactive atoms (50% of the number of atoms remain or 50% of the original activity is present)
Shows radioactivity and decay is an exponential decay function/asymptotic

Half-life (T^1/2)

91

SI and traditional unit of activity

SI: Becquerel (Bq)
Traditional: Curie (Ci)

92

1 Bq = ? disintegrations per second

1 disintegration per second

93

1 Bq = ? Curie (Ci)

2.7 x 10^-11 Ci

94

1 Ci = ? Bq

3.7 x 10^10 Bq

95

1 mCi = ? Ci = ? Bq

1 mCi = 1/1000 Ci = 3.7 x 10^7 Bq

96

A function whose value is a constant raised to the power of the argument

Exponential function

97

Line that gets closer to 0 but never touches

Asymptotic

98

Decay constant

λ = -ln2/T^1/2 = -0.693/T^1/2

99

ln2

0.693

100

Portion of atoms decaying per unit of time

Decay constant (λ)

101

Average lifetime of a radioactive atom; sum of all nuclei divided by total number of nuclei involved
Inverse of the decay constant

Mean/average life (Ta)

102

Formula for average life

Ta = 1.44(T^1/2)
Average life = 1.44(half-life)

103

How many known elements are there?

118

104

How many elements occur naturally?

The first 92

105

2 kinds of radioactive equilibrium

Transient equilibrium
Secular equilibrium

106

Half-life of parent is not much longer than the daughter
Daughter product appears to decay with the half-life of the parent
T^1/2 parent > T^1/2 daughter (about 10 times)
Ex: Mo-99 (67 h) > Tc-99m (6.7 h); equilibrium occurs at about 1.5 days

Transient equilibrium

107

Half-life of parent is much longer than the daughter
Daughter product appears to decay with the half-life of the parent
T^1/2 parent >> T^1/2 daughter
Ex: Ra-226 (1626 yrs) >> Rn-222 (3.8 days); equilibrium occurs at about 20-25 days

Secular equilibrium

108

Exponential function graph

Logarithmic

109

5 modes of decay

Alpha (a) = alpha particles
Beta (B-) or negatron = electron
Beta (B+) or positron = opposite of electron
Electron capture
Internal conversion

110

Type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms/decays into an atom with a mass number that is reduced by four and an atomic number that is reduced by two
When bonds are broken, energy is given up
Heavy mass and charge = high interactions with matter (high QF)
Mass and energy are interchangeable
4/2He
Parent -> daughter + radioactive particle + energy

Alpha (a) decay

111

Alpha decay is most frequent with _____ atomic numbers (Z>_____)

High, 82

112

(A/Z)X => (A-4/Z-2)Y + (4/2)He + Q (energy)

Alpha (a) decay

113

In what energy range does alpha decay occur?

4-8 MeV

114

How many times more effective in cell damage is alpha decay (high LET)?

20 x

115

Radiation absorbed dose

Rad

116

Radiation in man

Rem

117

Number applied to the absorbed dose at a point in order to take into account the differences in the effects of different types of radiation
Multiply by this to find the biological effect

Quality factor (QF)

118

3 things alpha decay gives off and 1 it ends with

2 protons
2 electrons
0 neutrons

Ends with a particle

119

Decay process which involves the ejection of a positron (B+) or negatron (B-)

Beta decay

120

(1/0)n --> (1/1)p + (0/-1) B + v

Negatron (B-) emission

121

Decay process which converts a neutron to a proton and gives off an electron
Has excess neutrons (high n/p ratio) that must be reduced by emitting an electron
Neutron => proton + (B-) + antineutrino + Q (energy)

Negatron (B-) emission

122

(1/1)p --> (1/0)n + (0/+1) B + v

Positron (B+) decay

123

Proton to neutron and kicks off betatron
Deficiency in neutrons (low n/p ratio)
Proton + energy (1.02 MeV) => neutron + (B+) + neutrino + Q (energy)
Proton --> neutron gives off positron to balance
1.02 MeV is the threshold energy; energy transmission of 1.02 MeV gets shared between the neutrino and positron
Mean energy is about E/3
Characteristic x-rays (27-31 keV)

Positron (B+) decay

124

Has no charge, no negligible mass, and hardly interacts with matter

Antineutrino

125

From where does beta decay originate?

From within the nucleus

126

Electron but with opposite charge

Positron (B+)

127

Rest mass of a beta particle

0.511 MeV

128

Alternative to positron decay; unstable nuclei deficient of neutrons seeks to increase n/p ratio (both reduce Z by 1)
Orbital electron gets captured by nucleus and combines with a proton, transforming into a neutron
Too many protons, needs more neutrons
Most often happens with K-shell (proximity) with heavier elements
Creates a vacancy in an electron shell => Auger electrons; atom reabsorbs energy then ejects an orbital electron with that energy

Electron capture

129

Characteristic and auger interactions are more probable with what Z?

Characteristic is more probable with high Z
Auger is more probable with low Z (<30)

130

(1/1)p + (0/-1)e --> (1/0)n + v + Q

Electron capture

131

Nucleus has excess energy after an interaction and passes it to an orbital electron => electron ejected from the atom
Atomic number remains the same, just becomes ionized/charged since there is a difference in electron composition
Alternative to gamma-emission

Internal conversion

132

8 nuclear reactions

a, proton
a, neutron
Proton bombardment
Deuteron bombardment
Neutron bombardment
Photodisintegration
Fission
Fusion

133

Change in the identity or characteristics of an atomic nucleus that results when it is bombarded with an energetic particle
Adding things together

Nuclear reactions

134

An element is bombarded with an alpha particle and gives off a proton
(A/Z)X + (4/2)He --> (A+3/Z+1)Y +(1/1)H + Q

a, proton

135

An element is bombarded with an alpha particle and gives off a neutron to remain stable
(A/Z)X + (4/2)He --> (A+3/Z+2)Y +(1/0)H + Q

a, neutron

136

A proton is captured by the nucleus and emits a gamma (y) ray; other less common proton reactions involve the nucleus capturing a proton, but emitting a neutron, deuteron, or alpha particle
An element is bombarded with a proton and gives off a different element and a gamma ray

Proton bombardment

137

Stable isotope of hydrogen with a mass approximately twice that of the usual isotope

Deuterium

138

(A/Z)X + (1/1)p --> (A+1/Z+1)Y + y (energy)

Proton bombardment

139

Deuterium nucleus
Normal proton with electron spinning around it with a neutron attached
(2/1)d or (2/1)H
One proton and one neutron

Deuteron

140

A nucleus is bombarded with a deuteron and emits a proton or neutron

Deuteron bombardment

141

2 types of deuteron bombardment

Proton produced
Neutron produced

142

Deuteron is not captured by the nucleus and passes close to nucleus; deuteron loses its proton (stripped off)
(A/Z)X + (2/1)d --> (A+1/Z)Y + (1/1)p

Deuteron bombardment when a proton is produced
Stripping

143

A nucleus is bombarded with a deuteron and emits a daughter and a neutron
(A/Z)X + (2/1)d --> (A+1/Z+1)Y + (1/0)n

Deuteron bombardment when a neutron is produced

144

Neutrons, lacking in charge are very effective at penetrating nuclei; a nucleus is bombarded with a neutron and emits an alpha particle
(A/Z)X + (1/0)n --> (A-3/Z-2)Y + (4/2)He

Neutron bombardment (n, y)

145

A high energy photon hits a nucleus and emits a nucleon(s), usually a neutron
(A/Z)X + y --> (A-1/Z)X (isotope) + 1/0n

Photodisintegration

146

(2/1)H + (3/1)H --> (4/2)He + (1/0)n + Q

Fusion

147

How much energy does a linac usually use?

6-18 MeV

148

Half-life of radium-226 (Ra)

1626 years

149

Half-life of radon-222 (Rn)

3.83 days

150

Half-life of cesium-137 (Cs)

30 years

151

Half-life of iridium-192 (Ir)

73.8 days

152

Half-life of cobalt-60 (Co)

5.26 years

153

Half-life of iodine-125 (I)

59.6 days

154

Half-life of palladium-103 (Pd)

17 days

155

Half-life of iodine-131 (I)

8.06 days

156

Rest mass of an electron (e-, B-, (0/-1)B) and positron (e+, B+, (0/+1)B)

9.11 x 10^-31 kg

157

Rest energy of an electron (e-, B-, (0/-1)B) and positron (e+, B+, (0/+1)B)

0.511 MeV

158

What is a practical use of electrons (e-, B-, (0/-1)B)?

RT treatment of shallow tumors

159

What is a practical use of positrons (e+, B+, (0/+1)B)?

Antimatter, PET imaging - gives off positron when it decays
Fluorodeoxyglucose (FDG) with F18 is metabolized like glucose and shows increased metabolic activity (cancer)

160

Charge of an electron (e-, B-, (0/-1)B)

-1

161

Charge of a positron (e+, B+, (0/+1)B) and proton (p or (1/1)H)

+1

162

Rest mass of a proton (p or (1/1)H)

1.672 x 10^-27 kg

163

Rest energy of a proton (p or (1/1)H)

938.3 MeV

164

What is a practical use of protons (p or (1/1)H)?

RT treatment

165

Charge of a neutron (n or (1/0)n)

0

166

Rest mass of a neutron (n or (1/0)n)

1.675 x 10^-27 kg

167

Rest energy of a neutron (n or (1/0)n)

939.6 MeV

168

What is the practical use of a neutron (n or (1/0)n)?

Containment after 10 Mv

169

(4/2)He

Alpha particle (a)

170

(1/1)p

Proton

171

(2/1)d

Deuteron

172

(0/1)n

Neutron

173

(0/-1)e or (0/-1)B

Electron

174

(0/+1)B

Beta plus

175

Amount of time the machine is on, directly proportional to dose

Monitor unit (MU)