RAD BIOLOGY 2

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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
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 or: 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 radi: 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 nuclea: 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

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