Test 1 Flashcards
Kilo- (k)
1000 units (10^3)
Hecto- (h)
100 units
Deka- (da)
10 units
Deci- (d)
0.1 units
Centi- (c)
0.01 units (10^-2)
Milli- (m)
0.001 units (10^-3)
Mega- (M)
1,000,000 units (10^6)
Speed of light
3 x 10^8 m/s
3 subatomic particles
Neutrons
Electrons
Protons
Neutrons and protons inside the nucleus
Nucleons
2 nucleons
Neutrons
Protons
Radius of the nucleus
10^-15 m
Radius of the electronic orbit of electrons around the nucleus
10^-10 m
The nucleus orbit is _______ than the electron orbit
Smaller
The mass of a nucleon is about _______ times that of an electron
2,000
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
Max number of electrons in each respective shell
2n^2
Electrons closer to the nucleus have ________ binding energy
Higher
Number of protons
Atomic number (Z)
Number of nucleons
Atomic mass number (A) (amus)
Formula for the number of neutrons
N=A-Z
How is the chemical identity of an element determined?
By the number of protons in the nucleus
What determines an element’s chemical behavior?
The number of electrons
Two atomic nuclei with the same atomic number/Z/number of protons but a different number of neutrons
Isotope
Same number of neutrons but different atomic number (Z)
Isotone
Same mass number/number of nucleons (protons + neutrons)/A, but different atomic number/number of protons/Z
Isobar
Same mass number/number of nucleons/A, but in a different nuclear state (metastable state/different energy level = excited state)
Isomer
Every gram atomic weight of a substance contains ______ number of atoms
The same
Avagadro’s number (NA)
6.0221 x 10^23 atoms per gram atomic weight (mole) or electrons/gram
Atomic mass unit
amu
1 amu = how many kg or Mev
- 66 x 10^-27
931. 4 MeV
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
1 amu is equal to what of a Carbon-12 atom?
1/12 of a Carbon-12 atom
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
Amount of energy required to remove an electron from the atom
Binding energy
Mass of a proton
1.00727 amu
Mass of a neutron
1.00866 amu
Mass of an electron
0.000548 amu
Formula for mass defect
Atomic mass number - ((# of P+ * 1.00727) + (# of N * 1.00866) + (# of E- * (0.000548))
Einstein’s Theory of Relativity
Energy (E) = mass (m) * speed of light (C)^2
kgm^2/s^2
Joules (J)
1 eV = how many J?
1.60218 x 10^-19 J
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)
Formula for converting mass defect (amu) to kg
Mass defect (amu) x (1.66 x 10^-27 kg/1 amu) = kg
Formula for converting energy (J) to eV
eV = J/1.602x10^-19 eV
Formula for converting eV to MeV
MeV = eV/1,000,000
Basic unit of energy
Joule (J)
1 J/kg = ? Rads = ? Gy
1 J/kg = 100 Rads = 1 Gy
100 cGy = ? Gy
100 cGy = 1 Gy
1 cGy = ? rad = ? Gy
1 cGy = 1 rad = 0.01 Gy
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
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
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
Resulting nucleus of radioactive decay that is more tightly bound
Some radioactive substances break down and give rise to a radioactive product
Daughter
Nuclei that do not undergo radioactive decay
Stable
Wave model (energy)
C=vλ
C=velocity
v=frequency (Hz or 1/sec)
λ=wavelength
Describes the relationship between energy and frequency (λ)
Plank’s constant
Graphs binding energy per nucleon vs. atomic number
Curve of binding energy (BE)
Average binding energy (BE) of most nuclei
8 MeV per nucleon
BE per nucleon reaches peak with what element?
Iron (Fe56)
Excess energy is released from radioactive decay as this
Gamma rays
Too many protons make the nucleus _______
Unstable
Ratio of neutrons to protons
1.4 neutrons for 1 proton
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
Particle with equal mass and magnitude to an electron but opposite sign of charge (+)
Postiron (e+)
Anti-electron
Every particle has an ______
Antiparticle
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
What is the energy of each gamma ray emitted during annihilation reaction?
0.511 MeV
Gamma radiation emitted during annihilation reaction
Annihilation radiation
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
What is common radiation therapy doses (Gy)?
1.8-2 Gy
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
Plank’s constant number (h)
6.62 x 10^-34 J-sec
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
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
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
931.4 MeV = ? amu
1 amu
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
Amount of substance that contains as many atoms as there are atoms in 12 grams of Carbon-12
Mole
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)
Phenomenon where radiation is given off in the form of particles or electromagnet waves; atom is attempting to become stable
Radioactivity
2 forms of radioactivity
Particle form
Electromagnetic
2 particle forms of radioactivity
Alpha (a)
Beta (B- or +)
2 beta particles
Electrons (B-)
Positrons (B+)
Helium nuclei
4/2He^2+ (2 protons, 2 neutrons, 0 electrons)
Travel a short distance in matter
Alpha (a) particles
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
All elements with Z greater than what are radioactive/unstable?
82 (lead)
Bismuth 83
Potential to decay, energy in an atom
Rate of decay; disintegrations per unit of time
Activity
Activity formula
At=Aoe^-λt
At = activity after time Ao= original activity t = time elapsed λ = decay constant (ln2/T^1/2)
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)
SI and traditional unit of activity
SI: Becquerel (Bq)
Traditional: Curie (Ci)
1 Bq = ? disintegrations per second
1 disintegration per second
1 Bq = ? Curie (Ci)
2.7 x 10^-11 Ci
1 Ci = ? Bq
3.7 x 10^10 Bq
1 mCi = ? Ci = ? Bq
1 mCi = 1/1000 Ci = 3.7 x 10^7 Bq
A function whose value is a constant raised to the power of the argument
Exponential function
Line that gets closer to 0 but never touches
Asymptotic
Decay constant
λ = -ln2/T^1/2 = -0.693/T^1/2
ln2
0.693
Portion of atoms decaying per unit of time
Decay constant (λ)
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)
Formula for average life
Ta = 1.44(T^1/2)
Average life = 1.44(half-life)
How many known elements are there?
118
How many elements occur naturally?
The first 92
2 kinds of radioactive equilibrium
Transient equilibrium
Secular equilibrium
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
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»_space; T^1/2 daughter
Ex: Ra-226 (1626 yrs)»_space; Rn-222 (3.8 days); equilibrium occurs at about 20-25 days
Secular equilibrium
Exponential function graph
Logarithmic
5 modes of decay
Alpha (a) = alpha particles Beta (B-) or negatron = electron Beta (B+) or positron = opposite of electron Electron capture Internal conversion
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
Alpha decay is most frequent with _____ atomic numbers (Z>_____)
High, 82
(A/Z)X => (A-4/Z-2)Y + (4/2)He + Q (energy)
Alpha (a) decay
In what energy range does alpha decay occur?
4-8 MeV
How many times more effective in cell damage is alpha decay (high LET)?
20 x
Radiation absorbed dose
Rad
Radiation in man
Rem
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)
3 things alpha decay gives off and 1 it ends with
2 protons
2 electrons
0 neutrons
Ends with a particle
Decay process which involves the ejection of a positron (B+) or negatron (B-)
Beta decay
(1/0)n –> (1/1)p + (0/-1) B + v
Negatron (B-) emission
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
(1/1)p –> (1/0)n + (0/+1) B + v
Positron (B+) decay
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
Has no charge, no negligible mass, and hardly interacts with matter
Antineutrino
From where does beta decay originate?
From within the nucleus
Electron but with opposite charge
Positron (B+)
Rest mass of a beta particle
0.511 MeV
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
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)
(1/1)p + (0/-1)e –> (1/0)n + v + Q
Electron capture
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
8 nuclear reactions
a, proton a, neutron Proton bombardment Deuteron bombardment Neutron bombardment Photodisintegration Fission Fusion
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
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
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
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
Stable isotope of hydrogen with a mass approximately twice that of the usual isotope
Deuterium
(A/Z)X + (1/1)p –> (A+1/Z+1)Y + y (energy)
Proton bombardment
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
A nucleus is bombarded with a deuteron and emits a proton or neutron
Deuteron bombardment
2 types of deuteron bombardment
Proton produced
Neutron produced
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
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
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)
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
(2/1)H + (3/1)H –> (4/2)He + (1/0)n + Q
Fusion
How much energy does a linac usually use?
6-18 MeV
Half-life of radium-226 (Ra)
1626 years
Half-life of radon-222 (Rn)
3.83 days
Half-life of cesium-137 (Cs)
30 years
Half-life of iridium-192 (Ir)
73.8 days
Half-life of cobalt-60 (Co)
5.26 years
Half-life of iodine-125 (I)
59.6 days
Half-life of palladium-103 (Pd)
17 days
Half-life of iodine-131 (I)
8.06 days
Rest mass of an electron (e-, B-, (0/-1)B) and positron (e+, B+, (0/+1)B)
9.11 x 10^-31 kg
Rest energy of an electron (e-, B-, (0/-1)B) and positron (e+, B+, (0/+1)B)
0.511 MeV
What is a practical use of electrons (e-, B-, (0/-1)B)?
RT treatment of shallow tumors
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)
Charge of an electron (e-, B-, (0/-1)B)
-1
Charge of a positron (e+, B+, (0/+1)B) and proton (p or (1/1)H)
+1
Rest mass of a proton (p or (1/1)H)
1.672 x 10^-27 kg
Rest energy of a proton (p or (1/1)H)
938.3 MeV
What is a practical use of protons (p or (1/1)H)?
RT treatment
Charge of a neutron (n or (1/0)n)
0
Rest mass of a neutron (n or (1/0)n)
1.675 x 10^-27 kg
Rest energy of a neutron (n or (1/0)n)
939.6 MeV
What is the practical use of a neutron (n or (1/0)n)?
Containment after 10 Mv
(4/2)He
Alpha particle (a)
(1/1)p
Proton
(2/1)d
Deuteron
(0/1)n
Neutron
(0/-1)e or (0/-1)B
Electron
(0/+1)B
Beta plus
Amount of time the machine is on, directly proportional to dose
Monitor unit (MU)
