Ch 2 & 8 Flashcards
(89 cards)
Studies relationships between matter and energy
Physics
Has mass and occupies space
Matter
The quantity of matter contained in an object
Mass
Force used to do work
Energy
Smallest particle of an element that still possess the chemical properties of that element
Atom
Simple substances
Element
Complex substances
Compound
A material that has definite constant composition
Simple vs complex, elements vs compounds, atoms vs molecules
Substance
Two or more substances combined
Mixture
Smallest particle of a compound possessing characteristics of the compound
Molecule
3 states of matter (dependant upon varying degrees of molecular attraction largely due to temperature)
Solid
Liquid
Gas
E=mc^2
<p>Law of conservation of energy (E = energy, m = mass, c = speed of light)</p>
<p>Unit of energy</p>
<p>Joule</p>
<p>Energy is emitted and transferred through matter; heat and light both come from the sun</p>
<p>Radiation</p>
<p>Mini solar system
| Electrons don't orbit perfectly, more like beehive</p>
<p>Bohr (1913)</p>
<p>Small dense center of atom that contains nucleons, protons and neutrons</p>
<p>Nucleus</p>
<p>Electrons can't be divided
Protons and neutrons made up of quarks
M theory (string theory): links this and relativity</p>
<p>Quantum physics</p>
<p>Distinguishes elements by number of protons contained in nucleus</p>
<p>Atomic number (Z#)</p>
<p>Atoms that have the same number of protons in the nucleus but differ in the number of neutrons</p>
<p>Isotope</p>
<p>Adding or removing of electrons from an atom
X-ray photons can interact with atom, results in the ejection of electrons
Changes charges between atoms
Causes disruptions in body's metabolic relationships (can harm patient) so exposing patients to this radiation thus requires order from licensed practitioner</p>
<p>Ioniziation</p>
<p>An atom that has gained or lost an electron</p>
<p>Ion</p>
<p>How many protons and neutrons in atom, neglects mass of atom's electrons
Mass of proton 1836 times greater than electron, mass of neutron 1838 times greater than electron</p>
<p>Mass number (A#)</p>
<p>Defines location where electron might be at any given time</p>
<p>Orbital</p>
<p>Chemical combining characteristics that describe how an atom will bond with other atoms
\+1 atoms gives up and electron, -1 atom gains an electron</p>
<p>Valence</p>
Energy needed to eject an electron from an atom, how tightly bound electrons are bound to the nucleus of that particular atom Related to how close electron is related to nucleus Increases as atomic number increases K shell energy greatest (electrons bound tighter than in other shells) Depending on how many protons are in the nucleus, the binding power will be stronger the higher the proton number (ex: H vs lead) Atoms have different number of protons in the nucleus which affect how tightly bound electrons will be Unit: electron volts (eV); energy of one electron when accelerated by one volt = keV
Electron binding energy (Eb)
Atom never has more than eight electrons in its outer shell, for this reason atoms begin to fill in next shell before maximum is reached Atom with eight electrons in outer shell chemically stable (inert)
Octet rule
Ability to do work, force acting upon object over distance expends this Work = force x distance
Energy
Action of physical movement
Mechanical energy
2 types of mechanical energy
Potential | Kinetic
Energy released from a chemical reaction Ex: body converts this energy from food into mechanical energy or mood; battery converts this energy into electrical energy
Chemical energy
Results from movement of molecules, temperature measures it Ex: toaster converts electrical energy to this
Heat/thermal energy
Electricity, results from movement of electrons in conductor Ex: light bulb converts electric energy to light
Electrical energy
Obtained by breaking bonds between particles within nucleus Ex: nuclear power plants convert this energy to electricity
Nuclear energy
Combination of electric and magnetic fields travelling through space, results from acceleration of a charge Can travel through medium or vacuum (x-ray tube = vacuum) Wave/particle duality Can cause excitation/ionization
Electromagnetic (EM) energy
EM travels in waves and there are little particles within each wave
Wave/particle duality
The distance between any two successive points on a wave; distance between two peaks
Wavelength
Number of waves that pass a particular point in a given time frame
Frequency (hertz, Hz)
Intensity of the wave defined by its maximum height
Amplitude
Waves are disturbances in a medium; ex: ocean, sound, etc. Wavelength: angstrom Frequency (v): cycles per second (Hz)
Wave theory
Frequency and wavelength are inversely related Velocity = frequency x wavelength (V = v x wavelength) Velocity of all EM radiation is c, c = 3 x 10^8 m/s c = v x wavelength
Wave equation
High frequency, high energy EM radiation Interacts like particle when contacting matter Photon (bundle of energy) energy and frequency directly related When bundle of energy interacts with something, it's able to break it apart; different bundles of energy in each x-ray If frequency doubled, energy doubles; E=hv
Particle theory
Who discovered x-rays and when?
Wilhelm Conrad Rontgen in 1895
12 x-ray properties
Penetrating and invisible form of EM radiation (can't be seen, stopped by lead) Electrically neutral (not affected by electric or magnetic field) Polyenergetic or heterogeneous energies (various energies/wavelengths) Release heat when passing through matter Travel in straight lines Travel at speed of light Can ionize matter Cause fluorescence in certain crystals Cannot be focused by lens Affect photographic film Produce chemical and biological changes in matter (patients) through ionization and excitation Produce secondary and scatter radiation
2 responsibilities of radiographers
Minimize dose | Protect patients and others from unnecessary exposure
2 sources of ionizing radiation
Natural | Man-made
2 groups of ionizing radiation
Particulate | Electromagnetic
High-energy electrons, neutrons and protons From radioactive decay Alpha and beta particles Used in nuc med
Particulate radiations
High-energy helium nucleus (two protons and two neutrons) Decaying radioactive material Large amount of mass and charge Can travel 5 centimeters (cm) in air, not very harmful external source but if injected in you it is one of the worst types of radiation Weighting factor of 20
Alpha particles
2 types of particulate radiation
Alpha | Beta
Electrons from decaying radioactive material Little mass and charge Can travel 10-100 cm in air, not as dangerous as alpha
Beta particles
2 types of biologic damage
Direct interaction | Indirect interaction
X-rays interact with water molecules which produce free radicals that cause damage More damage done in diagnostic field
Indirect interaction
2 classifications of biological effects of ionizing radiation
Somatic | Genetic
Evident in individual, w/in person who receives rad (patient or radiographer) Ex: burns, erythema (redness), cataracts, cancer
Somatic
Evident in offspring of individual | Birth defects
Genetic
6 things influenced by biological effects of ionizing radiation
Total dose received Rate of dose Age at exposure Type of radiation Sensitivity of cells Body part irradiated
```2 sources of ionizing radiation exposure
Natural Man-made
3 natural sources of ionizing radiation exposure
Cosmic radiation Terrestrial radiation Radionuclides naturally present (internal and external, injected in body for nuc med scans)
6 man-made sources of ionizing radiation exposure
X-rays Radiopharmaceuticals Consumer products (smoke detectors) Air travel (closer to sun) Nuclear fuel production Fallout
```5 major areas of radiation exposure in U.S.
Ubiquitous background, including Radon Medical procedures Consumer products Industrial and security activities Occupational exposure
```Number of ionizations in given quantity of air When you make an exposure, there are a bunch of photons that come out of the tube and through air and cause ionization Exposure in air; quantity of x-rays
Exposure
“The quantity of x-rays or gamma rays required to produce a given amount of ionization charge in a unit of mass air”; used in inverse square law
Roentgen (R)
Units of exposure
1 R = 2.58 x 10-4 C/kg | Roentgen (R)
Measures amount of energy absorbed | Unit can be used to measure any material
Absorbed dose
Conventional unit of absorbed dose
1 rad = 100 ergs/gm
SI unit of absorbed dose
1 Gray (Gy) = 1 Joule/kg
Kinetic Energy Released in Matter Radiation interacts with matter: energy carried by photon is transformed to kinetic energy to particles (electrons) At diagnostic energies equivalent to dose (rads/gray) Unit Gy
Kerma
Kinetic energy released per unit mass of air Used to describe tube output ant input to image receptors This of 1 cGy = 1 rad Equivalent to 1 R of exposure
Air kerma
Total amount of energy deposited in matter Ex: CT Abdomen 1 section delivers dose of 1 rad, 20 slices total Tissue volume of each section 1 rad = 20 rad No radiation in CT
Integral dose
Product of absorbed dose in tissue and radiation weighting
Equivalent dose (Ht)
Different types of ionizing radiation produce different biological responses X-rays have weighting factor of 1
Radiation weighting
Conventional unit of equivalent dose
rem
SI unit of equivalent dose
Sievert (Sv)
Sum of equivalent doses of specific tissues | Not all tissues are equally sensitive to radiation
Effective dose (E)
Describes quantity of radioactive material Expressed as number of radioactive atoms to decay per unit time Nuc med
Activity (A)
Conventional unit of activity
Curie (Ci) | 1 Ci = 3.7 x 1010 disintegrations per second (dps)
SI unit of activity
Becquerel (Bq) | 1 Bq = 1 dps
Dose-measuring device
Dosimeter
2 classifications of dosimeters
Field survey instruments | Personnel monitoring devices
3 types of field survey instruments
Geiger-Mueller survey instruments Scintillation detection devices Ionization chamber instruments
Gas-filled detector (volume of gas between two electrodes) Ionizing radiation creates ion pairs in gas Used to demonstrate presence of radiation Not for precise measurement Most effective with particulate radiation Common use in nuc med Least effective in detecting x- or gamma radiation
Geiger-Mueller Survey Instruments (GM counters)
Emit light when stimulated by ionizing radiation Light converted to electric signal Commonly used in nuclear medicine and CT scan equipment
Scintillation detection devices
Diagnostic Used to evaluate equipment performance, leakage radiation and patient exposure Gas filled chamber, anode, cathode & automatic readout Configuration Mechanism of action
Ionization chamber instruments
Provided to workers who could accumulate 1/10 of recommended dose limit Should be worn at level of collar
Personnel Monitoring Devices
4 personnel monitoring devices
Optically stimulated luminescence (OSL) dosimeter Film badge dosimeter Thermoluminescent dosimeter (TLD) Pocket dosimeter
```Most common type of personnel monitor Detector: thin layer of aluminum dioxide Laser light processing of aluminum dioxide causes luminescence (level of luminescence proportional to amount of exposure received) Filters of copper and tin and an open window demonstrate energy of exposure and if exposure occurred while static or in motion Issued on monthly or quarterly basis Sensitive to 1 millirem (mrem): picks up on very small amount of radiation (better than others) Environmentally stable and durable
Optically stimulated luminescence (OSL) dosimeter
Detector: two pieces of film in light tight packet Packet placed in holder with filter elements (copper, cadmium, and aluminum; filters provide information on energy of radiation) Film processed and optical density evaluated Demonstrates amount of exposure Sensitive to 10 mrem, readings under 10 mrem not detectable (reported as M) Environmentally sensitive to heat, humidity, pressure, prolonged exposure to light
Film Badge Dosimeter
Detector: lithium fluoride crystals Crystals store energy when exposed to ionizing radiation and release stored energy when heated as visible light Amount of light released proportional to amount of exposure Sensitivity similar to film badge: 10 mrem Environmental sensitivities also similar to film badges Heat, humidity, temperature, pressure, and prolonged exposure to light Compact design Desirable for extremity badges Small & often made into rings
Thermoluminescent dosimeter (TLD)
Ionization of air in small chamber Readout occurs digitally Can be read from display on side of dosimeter No permanent record
Pocket dosimeter | Electronic Personal Dosimeter
