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141 Cards in this Set

  • Front
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process of emitting radiant energy in the form of waves or particles
radiation
energy that is transmitted
radiation
found certain electronic tubes could emit radiant enery
1895, Roentgen
x stands for
unknown quantity
discovered certain natural thing emmitted radiation and discovered 3 types of radiation
1896, Becquerel
later named the 3 types of radiation alpha, beta, and gamma
Ernest Rutherford
electrically neutral
(same number of electrons as protons)
atom
3 types of particles
electron
proton
neutron
very light particles that revolve around the nucleus in orbits
charge of -1
electron
particles with a mass about 2000 times that of the electron
charge of +1
proton
The number of protons in the nucleus is
Z number or the atomic number
particles with about the same mass of a proton electrically neutral
neutron
protons and neutrons are found in the
nucleus
protons and neutrons are made of particles called
(building blocks of an atom's nucleus)
quarks
list the 6 types of quarks
up
down
strange
charm
truth
beauty
electrons are not made up of smaller particles
an electron is a type of particle called
lepton
same number of protons
different number of neutrons
the additional neutrons to the nucleus may make it radioactive 1) particulate
2) electronmagnetic
isotopes
mass of 4 amu (atomic mass unit)
CHARGE OF +2
doubly ionied helium atom
in air, 1 cm/MeV of energy
travel 4-8 cm
low penetration
Alpha
more penetrating than alpha particles
travel approximatley 12 feet/MeV of energy in air
travel several millimeters in tissue
mass of 0.00055 amu
charge of -1 or +1
Beta
uses of beta rays
radioactive phosphorus helps reduce fluid accumilation
Iodine-131 helps to treat thyroid CA (beta and gamma)
negative electron
produced by radioactive decay
Negatron
positive electron
radioactive decay or pair production
Positron
ionizing radiation and electromagnetic waves
x and gamma radiation
all electromagnetic waves have the same
velocity
Characteristic frequency (highest)
wavelengths (shortest)
amplitudes
travel in empty space
x and gamma radiation
originate from within the nucleus
gamma rays
originate from outside the nucleus
x-rays
a measure of the amount of ionization produced by x-radiation or gamma radiation in air (below 3 MeV)
roentgen
unit of measurement used for calibrating x-ray equipment
coulombs per kilogram
radiation absorbed dose
rad
100 rads =
1 gray
dependent on the penetrating ability of the radiation and the composition of the absorbing matter
f factor
radiation equivalent man
quantity of any ionizing
rems
100 rem =
1 Sv
measures radioactive decay of material (half-life)
curie
based on 50% original actvity
becquerel
milli
1/1000 th of the unit
larger unit to milli #
multiple the larger unit x 1000
smaller unit to larger unit
divide by 1000
amount, rate, & distribution of radiation emitted
dosimetry
detects and measures exposure to radiation
dosimeter
person who plans dosage and pattern in radiation therapy
dosimetrist
amount of radiation by collecting ions in a chamber filled with helium or argon gas
ionization chamber
determine exposure rate measurements in millroentgens per hour
ionization chamber
monitor staff/visitors in pt's room that has a radioactive implant
ionization chamber
great for x, gamma, and high-energy beta rays
ionization chamber
detects radiation sources and low level radioactive contamination (rate meter)
Geiger-Mueller counter
uses a sodium iodine crystal that produces flashes of light (scintillation)
similar to an AEC system
pocket ionization chambers
most sensitive detector of x and gamma radiation
pocket ionization chambers
Basic Rules of Using Field Survey Instruments
1. read the instructions
2. chech batteries before use
3. handle carefully
4. keep calibrated
5. store securely, access quickly
sensitive to doses as low as 10 mrem (0.1 Sv)
most sensitive to an energy of 50 keV
film badges
advantages of film badges
in use since 1940's (most popular)
inexpensive
easy to handle/easy to process
disadvantages of film badges
wait for reading
accurate only at 10 mrem and higher
fogs due to humidity, temp, light leaks
film badge reports for x =, gamma radiation (penetrating x rays)
deep
film badge reports for beta, low -energy x and gamma radiation
shallow
basic features of personnel monitoring
portable
rugged
sensitive
reliable
low cost
true or false
a seperate badge must be worn at each job
true
where should your badge be worn?
at the level of the sternum
lab jacket collar
should the film badge be worn outside or inside a lead apron
outside
common mistakes made while wearing a film badge
washing and drying film badge
LEAVING IT on a lead apron
leaving it on the dash of car
not always wearing it
not inserting it correctly into the holder
not being responsible
uses lithium fluoride crystals that absorb energy
can be worn up to 3 months
sensitive as low as 5 mrem (0.05 mSv)
Thermoluminescent Dosimeters
Advantages of Thermoluminescent Dosimeters
are tissue equivalent
wear up to 3 months
can be reused
are highly accurate
do not fog
Disadvantages of Thermoluminescent Dosimeters
are expensive
do not provide a permanent record
break
looks like a pocket flashlight, electrode is positively charged
pocket dosimeters
advantages of pocket dosimeters
can be used for periods
can give immediate readings
disadvantages of pocket dosimeters
charge can leak = false reading
trauma can change reading
most sensitive / subject to false readings
no permanent record
particle spectrum
mass of 4 amu
charge of +2
doubly ionized
travel 4-8 cm
lowest penetration
most ionizing
alpha
particulate
more penetrating 12 ft/MeV of enery air
travel several millimeters in tissue
mass of 0.0005 amu
charge of -1 or +1
Uses
beta
radiation equialent man
REM
occupational exposure
Quaintity received by workers
Rems effects on organs
amount of biological effects (effectiveness)
difference in anysis of film badges
some types of radiation produce more damge than x-rays
Amounts of effects is based on the effective dose
(how it is used and how it relates to the absorbed dose)
1 sievert = __ rem
100 rem
Radiation absorbed dose
rad
Dose to biological material
evergy deposited in tissue
rad
Fraction of RAD depends on the energy (penetrating ability of the radiation and the composition of the absorbing material)
rad
f factor
any type of ionizing radiation to expose the matter (can come from difference sources)
amount of radiation transferred to an object (dose to patient)
amount of energy absorbed by an object
rad
Rad =
Gray
1 gray= __ RAD
100 RAD
the number of photons that are absorbed in the patient
absorption
reduction in number of photons as they pass through matter
(due to absorption or deflection of the beam)
attenuation
Monoenergetic radiation
emitted with a single energy therefore, attenuation is an exponential process
gamma radiation
beam is consistent/amount of absorber will reduce the intensity to HVL
half value layer
____ can interact with the entire atom, nucleus or an orbital electron (influenced by the photon's energy)
photons
Middle energies
orbital electrons
hight energies
(MeV therapy) interact with the nucleus
closest to positive charged nucleus
greatest force of attraction to nucleus (binding energy)
k shell electron
the farther an electron is form the nucleus, the _____
binding energy and the ____ the energy level
lower
higher
four factors affect attenuation
transmission
number of photons
density
atomic number
interaction with matter in which a photon strikes an inner shell electron, causing its ejection from orbit with the complete absorption of the photon's energy
photoelectric effect
more likely to occur in bone, as opposed to soft tissue
photoelectric effect
atomic number of bone
13.8
in photoelectric absorption, the incident photon is ____ absorbed
completely
interaction are more likely to occur if the x-ray photons' energy is greater than, but close to, the binding energy of the electron
photoelectron interactions have a greater likelihood of occurrence when the electron is more tightly bound to its orbit (basis for lead aprons)
photoelectric effect
The loss of an electron causes the atom to be positively charged or a/an
ionized Ion pair: atom and electron
number of ion pairs produced per unit of distance traveled
specific ionization
if LET is increased/si is
increased
alpha and beta
increased LET/increased si

less penetrating but causes more damage
x and gamma LET
Decreased LET/ decreased si

more penetrating but don't give up energy quickly
electrons move closer to the nucleus shell by shell
characteristic cascade
interaction with matter in which a low-energy photon (below 10MeV) is absorbed and released with its same energy, frequency and wavelength but with change of direction
coherent scattering
classic
Thomson
refers to as "unmodified scattering" occurs when a very low energy x-ray photon interacts with a relatively bound orbital electron and sets it into vibration. Unmodified scattering occurs in energy levels below the range useful in clinical radiology.
coherent scattering
Causes excitation rather than ionization
coherent scattering
coherent scattering results in a
change of direction of the incident photon
interaction with matter in which a higher-energy photon strikes a loosely bound outer electron, removing it from its shell, and the remaining energy is released as a scattered photon
compton scattering
occurs when the x-ray photons interact with a loosely bound OUTER shell electron
compton scattering
can pose a danger for radiology personnell especially during fluroscopy
compton scattering
acquires a certain amount of kinetic energy which must be subtracted from the energy of the entering photon
compton electron
As Z number increases the probability of Compton scatter
decreases
the energy of the incident photon is ___ absorbed
partially
incoming x-ray photon from the primary beam
incidetn photon
less energy than the incident photon
longer wavelength
lower frequency
compton photon
0-180 degrees
scatter
interaction between matter and a photon possesing a minimum of 1.02 MeV of energy, producing two opposite charged particles
pair production
occurs when a megavoltage with energy of at least 1.02 MeV splits into a positron and negatron
pair production
conversion of mass into energy
Annihilation
does nto occur in diagnostic radiology (nuclear industry only) x-ray photons with a minimum of 10 MeV of energy that can interact directly with the nucleus of the atom. Causes a state of excitement within the nucleus, followed by the emission of a nuclear fragment.
photodisintregration
no charge in the total energy of the interacting particles
elastic
total kinetic energy is changed
inelastic
rate at which energy is deposited in the form of a charged particle as it travels through matter
Linear Energy Transfer (LET)
amount of radiation absorbed by the patient
dose
5 methods of dose
1. skin
2. ESE
3. depth dose
4. organ dose
5. intergral dose
radiation received by a portion of the patient's skin max. dose any tissue will receive during this exposure most often used easiest to measure
skin dose
used to regulate diagnostic exposures based on technical factors
Entrance skin dose
measures percentage of skin dose at certain depths
depth dose
conversion of mass into energy
Annihilation
does nto occur in diagnostic radiology (nuclear industry only) x-ray photons with a minimum of 10 MeV of energy that can interact directly with the nucleus of the atom. Causes a state of excitement within the nucleus, followed by the emission of a nuclear fragment.
photodisintregration
no charge in the total energy of the interacting particles
elastic
total kinetic energy is changed
inelastic
rate at which energy is deposited in the form of a charged particle as it travels through matter
Linear Energy Transfer (LET)
amount of radiation absorbed by the patient
dose
5 methods of dose
1. skin
2. ESE
3. depth dose
4. organ dose
5. intergral dose
radiation received by a portion of the patient's skin max. dose any tissue will receive during this exposure most often used easiest to measure
skin dose
used to regulate diagnostic exposures based on technical factors
Entrance skin dose
measures percentage of skin dose at certain depths
depth dose
amoutn received by a specific organ
organ dose
total amount of energy absorbed by a specific mass of tissue
integral dose
output intensity varies directly with
mAs and the square of the kVp
inverse relation ship with the square of the distance from the focal spot K is constant
inverse relation ship with the square of the distance from the focal spot K is constant
Output intensity
K (mAs) KVP2
over
d2
Exposure from Radionuclides
1. the amount of the radionuclide in curies
2. the physical half-life of the radionuclide
3. the mixture of radiation emitted
4. the biodistribution
5. the biologic half-life of the material
x and gamma pass through matter by
absorption
attenuation
transmission