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Trimester 7 > x-ray physics- unit 1 lectures > Flashcards

x-ray physics- unit 1 lectures Flashcards

1
Q

what is matter composed of?
what are the 3 subatomic particles that atoms have?
what is the nucleus composed of?
what do the electron shells contain?
in a stable atom the # of electrons and protons are?
which model of the atom is considered the most representative of structure of matter?

A
  • atoms
  • protons (p+) / neutrons n0/ electrons e-
  • nucleus composed of protons and neutrons
  • electron shells contain orbital electrons
  • stable atom the # of e- and p0 is EQUAL
  • Bohrs model is the most representative of structure of matter
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2
Q

what are in constant motion around the nucleus?
what determine the energy of the shell?
what is the electron binding energy?
how is electron binding energy measured?
how is each shell identified?
which shell is the closest to the nucleus?
which shell has the most binding energy?
list the shells starting from nucleus out?

A
  • orbital shells are in constant motion
  • the distance from the nucleus determines the energy
  • EBE is the amount of energy needed to remove the electron from an atom
  • it is measured in KeV
  • identified by a letter
  • K is the shell that is closest to the nucleus
  • the most binding energy is the K shell
  • K-L-M-N-O-P-Q
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3
Q

as the atomic # increases, the K shell binding energy does what?
what is the binding energy of tungsten?

A
  • the K shell binding energy increases

- the binding energy of tungsten is 69.5 keV

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4
Q

what is mechanical energy result of?
what is potential energy?
what energy is “in motion” ?
what type of energy is released in a chemical reaction?
what energy is motion at the molecular level?
when electrons move through an electrical wire it is called what energy?
the energy contained in the nucleus of an atom is called?
what is electromagnetic energy- what does it involve?

A
  • mechanical energy is action of machines or physical movement
  • the capacity to do work (stored)
  • kinetic energy is energy in motion
  • chemical energy is released in a chemical reaction
  • heat and thermal energy is motion at the molecular level
  • moving through an electrical wire is called electrical energy
  • energy in the nucleus of atom is nuclear energy
  • EME is electrical and magnetic disturbances in space and involves many forms including x-rays and gamma rays
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5
Q 
what are some natural sources of electromagnetic radiation? 
what are cosmic rays?
what is terrestrial radiation
what EM is part of human metabolism? 
what are some artificial sources of EM?
A
  • cosmic rays/ terrestrial radiation/ radionuclides are natural sources
  • particles that are emitted by the sun and stars
  • emitted from deposits of uranium, thorium and other radioactive substances found in the earth
  • radionuclides- radioactive nucleus- potassium-40 part of metabolism
  • artificial forms of EM are tobacco/ tv/ smoke detectors/ x-rays
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6
Q

what is binding energy?
as the number of protons increase so does the binding energy of what?
how does the positive charges in the nucleus effect the atoms?
which electron is harder to remove from the nucleus?

A
  • the energy needed to remove an orbital electron from the atom
  • the binding energy of a given electron increases
  • atoms with high atomic # are bound more tightly than atoms with low atomic #
  • it takes more energy to remove a K shell electron than a shell farther away from the nucleus
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7
Q

x-rays are a form of what?
where are they created and when?
EM weak radiation is called? and highly penetrating rays are called?
what is the range of various forms of EM radiation called?

A
  • man-made electromagnetic energy.
  • created in an x-ray tube when high speed electrons are suddenly stopped
  • weak is thermal rays to highly penetrating gamma rays
  • the range is called electromagnetic spectrum
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8
Q

what differs between one form of EM and another?
what about velocity in forms of EM radiation?
what is equal to the speed of light?

A
  • frequency and wavelength
  • velocity is the same for all forms of EM
  • velocity is equal to the speed of light
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9
Q

when traveling through space, EM radiation behaves ?

when interacting with matter, EM radiation behaves as?

A
  • as a sine wave

- as a particle

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10
Q 
according to wave theory how does the EM energy travel?
describe wavelength?
how is it measured? 
what is the frequency? 
what is the unit of frequency?
A
  • travels in forms of sine waves
  • distance between 2 successive points
  • measured crest to crest or trough to trough
  • the frequency is the number of waves that passes a given point in a given time frame- number of cycles per second
  • unit of frequency is hertz
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11
Q

what is the wave equation?
what is the same for all forms of EM radiation?
which two properties are inversely proportional to one another?
photon energy is directly proportional to what?
photon energy is inversely proportional to what?
what frequencies and wavelength are at the bottom of the spectrum?
give an example of these?
where is visible light located on the spectrum?
what type of frequency and wavelength are located at the top of the spectrum?
give an example of these?

A
  • velocity=frequency X wavelength
  • velocity is the same- “speed of light”
  • frequency and wavelength are inversely proportional to one-another
  • photon energy is directly proportional to frequency
  • photon energy is inversely proportional to wavelength
  • at the bottom of the spectrum are low frequencies and long wavelengths
  • an example of these would be radio and microwaves
  • at the top of the spectrum are high frequencies and short wavelengths
  • an example of these are gamma and x-rays
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12
Q
  • when were x-rays discovered?
  • who were they discovered by?
  • describe the x-ray and properties?
A
  • x-rays discovered in november 8, 1895
  • discovered by dr. whilhelm conrad roentgen
  • x-ray properties include: - highly penetrating form of electromagnetic radiation/ electrically neurtral- not effected by electric or magnetic fields/ cam be polyenergetic and heterogeneous (wide variety of energies and wavelengths) / release small amounts of heat as it passes through matter/ travels in straight lines/ travels at the speed of light/ can ionize matter/ causes fluorescence- emission of light/ cannot be focused by a lens/ affects photographic film/ produces chemical and bilogical changes in matter through ionization/ produces secondary and scatter radiation.
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13
Q

how are x-rays produced?
what is this called?
how is electricity involved?

A
  • produced when high energy electricity produces high speed electrons that interact with matter
  • this is called an anode
  • electricity involved in distribution and movement of electrons
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14
Q

in electrodynamics what is the electrical circuit?
what is the “source” of electrons and how does it move?
what are the sources of excess electrons?

A
  • electrical circuit is the pathway that permits electrons to move through resisting electrical devices and back to the source.
  • the negative pole is the source of electrons which moves toward the positive receiving pole
  • sources of excess electrons include: batteries, generators, solar converters and atomic reactors
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15
Q
  • what are some common factors used to describe electrical flow or electricity?
A
  • quantity # of electron flow
  • force of electron flow
  • opposition to the flow of electrons
  • direction of electron travel
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16
Q 
the quantity of electron flowing = what? 
what does the current refer to?  
what is the unit of current? 
what is found on all x-ray machines? 
what does it regulate and produce?
A
  • the quantity of electron flowing = amp
  • the current refers to the quantity or number of electron flowing- the number of electrons flowing past a given point per unit of time.
  • the unit of current is the ampere or amp or milliamperage (same as amp)
  • milliamperage (mA) found on all x-ray machines to regulate the number of electrons available to produce an x-ray photon.
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17
Q 
what does the force of electron flow = ? 
what is the unit of force? 
the force is the strength of? 
kVp is found where? 
what does kVp regulate and when? 
what does kVp stand for?
A
  • force of electron flow = volt
  • the unit of force is the volt
  • the force is strength of electron flow
  • kVp is found on all x-ray machine to regulate the force of electrons striking the anode, when producing x-ray photons
  • kVp stands for kilovoltage peak
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18
Q

define resistance?

what is the unit of resistance?

A
  • resistance is the amount of opposition to the current in a circuit
  • unit of resistance (impedance_ is the OHM
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19
Q

how is direction described?
what is DC define?
what is AC define?

A
  • direction is described as DC or AC
  • DC is direct current- all electrons move in the same direction all of the time
  • AC is alternating current- electrons first move in one direction then reverse and flow in the opposite direction
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20
Q

which radiolucent tabletop permits c-rays to pass through?
which do not permit tilting of the up or down
which tabletop allows the table to move up and down? standing position and trendelen

A
  • floating tabletop and stationary tabletop
  • fixed table
  • tilting tabletop allows up and down movement
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21
Q

who invented the bucky?

what is it?

A
  • bucky tray is named for Dr. Gustav Bucky who was inventor of radiographic grid
  • it is installed over the film cassette
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22
Q

how many tube supports are there?

describe the 3 most common?

A
  • 5 versions

- overhead- floor to ceiling and floor

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23
Q

what type is this?

A

overhead

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24
Q

what type of support is this?

A

floor support

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25
Q

describe the upright units?
what is the AKA for upright bucky
is it movable or unmovable radiographic grid?
where is the film loaded into?

A
  • wall bucky
  • movable radiographic grid
  • cassette tray
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26
Q

what is the power to x-ray generator called?
how is the electricity supplied to the building?
what is this power called? and aka?

A
  • called in-coming line current
  • electricity supplied by 60 hertz AC/ 3-phase power cycle/ nearly all x-ray equipment operates from an incoming line of 210-220 bults
  • the power is called incoming line current or Mains
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27
Q

what is the purpose of the x-ray generator?

what does it allow the operator to select and control?

A
  • allows the operator to select and control the kilovolts peak - kVp and milliamperage mA and time in seconds mAs necessary for the examination
  • allows the operator to select the focal sopt size appropriate to the requirements of the exam
  • allows the operator to choice a manual or automatic exposure timing
  • increase the low voltage from the utility company to high voltage - kilovolts- necessary for x-ray production
  • converts AC from the tuility company to pulsating DC required by the x-ray tube to allow electron to flow from the cathode to the anode
  • protects the operator and patient from electrical shock from high voltage involved when using the x-ray machine
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28
Q

the x-ray circuit is divided into two circuits- what are they?
describe main circuit and what it supplies the x-ray tube
what does filament circuit supply?

A
  • divided into main and filament circuit
  • main circuit supplies the x-ray tube with the high voltage kVp0 need
  • filament circuit supplies the filament of the x-ray tube with power
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29
Q

what does main x-ray circuit do and what does it include?

A
  • it modifies the incoming line current to the high voltage necessary to produce x-ray
  • main breaker/ autotransformer and kVp selector/ exposure switch
    / exposure timer/ step-up transformer/ ground/ rectification circuit
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30
Q

what does the main breaker do?

A
  • it controls the incoming line current and protects the equipment from overload
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31
Q

what is autotransformer and kVp selector used for?

what does the kVp readout show?

A
  • used to select a pre-determind kVp

- kVp readout on the console shows the kV that will be applied to the x=ray tube- determines how hot it sill gets

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32
Q 
what is the exposure switch? 
what does it initiate? 
what does dead man type prevent? 
what does the first half initiate? 
what does the anode turn at high speed? 
what does the second half initiate?
A
  • it is a two-stage dead man type switch
  • exposure switch initiates exposure
  • dead man type prevents the exposure from continuing when tech is in the room- it is a safety device. - the moment you let go it stops.
  • the first half- activates the rotor- (the rotating anode and heats the filament)
  • anode must turn at high speed to avoid melting the target area with high kVp exposures
  • the 2nd half initiates the exposure
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33
Q

what terminates the exposure?
what are the different types?
what does the electronic timers terminate?
what does the automatic exposure control timers used to provide?
what does it terminate?
what does it rely on?

A
  • the timer circuit terminates the exposure
  • electronic timers and automatic exposure control timers
  • the electronic timers terminate the exposure when the set “time” is reached
  • the automatic exposure control timers are used to provide consistency of radiographic quality
  • the automatic exposure control timers terminates the exposure when set amount of radiation is detected by the chambers
  • it relies on excellent positioning skills and knowledge of anatomy of interest
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34
Q

what is function of step-up transformer?

what is needed to produce x-rays in the x-ray tube?

A
  • step up transformers is to increase the voltage selected by the autotransformer-
  • kVp selector and step it up to te kVp level needed to produce x-ray in the x-ray tube
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35
Q

where is the “ground” located?

what is the function of the “ground” ?

A
  • the ground is located on the high voltage side of the step-up transformer
  • the function is to ground the equipment for safety
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36
Q

what is the function of rectification circuit? why?

what is “voltage ripple”? is it good or bad?

A
  • the rectification circuit converts AC from the step-up transformer into pulsating DC for x-ray production
  • because the x-ray tube requires DC for x-ray production- allows electron to flow only form the cathode to anode in the x-ray tube
  • peak to trough is called “voltage ripple” it represents fluctuation in the power supply to the x-ray tube which is BAD
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37
Q

what is this?

A

x-ray circuit

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38
Q

what is the function of the filament circuit?
when electricity flows through the filament what happens?
what does mA setting control?
what happens when mA is increased?
what does filament circuit regulate?
what does filament circuit consists of?

A
  • the filament circuit modifies the incoming line power to produce thermionic emission from te filament wire- (x-ray tube)
  • when electricity flows through the filament, it gets hot causing electrons to “boil off” through thermionic emission
  • mA setting determines how hot the filament gets and how many electrons boil off
  • increase mA, filament gets hotter, more thermionic emission, larger space charge cloud (bundle of electrons around the filament)
  • filament circuit regulates the number of electrons available at the filament to produce x-rays
  • filament circuit consists of variable resistor (mA selector) and step-down transformer
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39
Q

where is the variable resistor located?

what is the function?

A
  • variable resistor is an mA selector on the control panel

- modified the voltage and amperage to the correct level for the step-down transformer

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40
Q

what is the filament transformer?
what is the function?
what does mA determine
what does the filament current determine?
when the temperature is higher what happens?

A
  • the filament transformer is a step-down;
  • filament transformer function- it steps-down voltage and increases amperage to heat the x-ray tube filament
  • mA (amperage) determines how hot the filament will get and how many electrons are available to produce x-rays
  • the filament current (A) determines the temperature of the filament- thus the number of electrons that will be available to bombard the target
  • when the temperature is higher the amount of electrons available and the quality of x-rays emitted from the tube is greater?
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41
Q

when are x-rays produced?

what are the 4 things needed to produce x-rays?

A
  • x-rays are produced when high speed electrons are suddenly slowed or stopped
  • the 4 things needed to produce x-rays are: source of electrons/ method to accelerate the electrons/ ways to suddenly decelerate or stop electrons / vacuum
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42
Q

what does the x-ray tube consist of?

what is it surrounded by?

A
  • x-ray tube consists of cathode assembly / anode assembly and glass envelope
  • the x-ray tube is surrounded in a protective housing
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43
Q

what is cathode assembly?
what does it consists of
what does the filament provide?
what does the focusing cup do?

A
  • it is a negative electrode in the x-ray tube
  • it consists of filament and focusing cup
  • the filament provides the source of electrons
  • the focusing cup focuses on high speed electron speed electron stream across the tube toward the focal spot
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44
Q

what is the filament structure?
what is the primary material
what material is added and for what reason?
what is a compromised vacuum called?
most x-ray tubes have what kind of arrangement?
these allow for what kind of focal spots?
what is this tube called?

A
  • filament structure is a small coil of thoriated tungsten alloy wire.
  • the primary material is tungsten
  • the added material is thorium to reduce vaporization
  • a compromised vacuum is called a “gassy tube”
  • most x-ray tubes have a dual focus arrangement with 2 filaments- a long filament and a short filament.
  • these allow the selection of a large or small focal spot
  • this type of tube is called a DUAL FOCUS TUBE
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45
Q

what is the filament function?
how does this process work?
what is the bundle of electrons called?
what is this process of electrons boiling off called?

A
  • filament produce the source of electrons needed to produce s-rays
  • resistance or friction causes the filament to heat- when the filament is hot enough, electrons will boil off of the filament producing a bundle of electrons surrounding the filament.
  • the bundle of electrons is called “space charge cloud”
  • the process of electrons boiling off in response to heat is called THERMIONIC EMISSION
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46
Q

what is the function of the focusing cup?
what type of charge does it have?
what is the purpose?

A
  • function of focusing cup is to house the filaments
  • the focusing cup has a negative charge
  • the purpose is to narrow the thermionic cloud as it is riven toward the anode
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47
Q

what is anode assembly?

what does is consists of?

A
  • the anode assembly is positive electrode of the x-ray tube

- it consists of the anode disc/ molybdenum stem/ and AC induction motor

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48
Q

what is the anode role?
primary function?
what is the anode a source of?

A
  • the role of the anode: diagnostic x-ray tubes are typically rotating anodes for heat dissipation
  • the primary function of the anode is to serve as the target surface or focal spot
  • the anode is a source of photon production
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49
Q

what is the focal track alloy?

what is the primary metal of choice for x-ray production?

A
  • focal track is a tungsten-rhenium alloy

- primary metal of choice for -ray production is tungsten

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50
Q

what is the anode connected to and how?

the AC induction motor rotates the anode allowing what?

A
  • anode is connected to the alternating current induction motor by a molybdenum stem
  • ## the AC induction motor rotates the anode allowing it to dissipate heat without damage (rotates at 10,000 rpm)
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51
Q

define anode angle?

what is the most common diagnostic radiographic target angle?

A
  • anode angle id the angle of the target surface with respect to the central ray in the x-ray field
  • the most common diagnostic radiographic target angle is 120 degrees
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52
Q

what is the target area of the anode?
what are the AKA’s for target area?
the “target is the point that all distances are ?

A
  • the target area of the anode is the portion of the anode where high voltage electron stream will impact, and x-rays are produced.
  • the aka’s are target, SID focus, focal point, focal spot
  • the target is the point that all distances are MEASURED
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53
Q

describe the anode focal spot?
what is the effective focal spot?
what does the length of the filament determine?
the filament length controls what?
what does equipment with a dual focus tube allow?
what is a small focal spot? what are the pros and cons?
what is a larger focal spot? what are the pros and cons?

A
  • the anode focal spot is the actual focal spot on the anode that the electrons stream actually strike during the exposure and were x-ray photons are produced.
  • the effective focal spot is the area of the focal spot projected out of the tube.
  • the length of the filament determines the size of the focal spot
  • the filament length controls the electrons stream width- therefore, how large of an area the electron stream strikes on the anode.
  • equipment with a dual focus tube (two filaments) allows the selection of a large or small focal spot.
  • small focal spot uses the short filament- pro/ provides better image spatial recorded detail/ con- can only be used for lower mA techniques due to the amount of heat generated on a small area of the anode.
  • the larger focal spots can sustain higher mA techniques uses the long filament/ pro- higher mA tech. can be used and con- produces images with decreased recorded detail .
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54
Q

what is line-focus principle?

what does tis permit?

A
  • it is a geometric principle used to reduce the size of the effective focal spot
  • it permits the best recorded detail wile permitting as large an actual area as possible for heat dissipation
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55
Q

define the anode heel effect?

A
  • the x-ray beam intensity along the anode- cathode axis varies- greater on the cathode side- the x-ray produced from the anode side of the tube must pass through the heel of the anode- a decrease in the intensity (number of photons) of the x-ray beam on the anode side of the tube.
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56
Q

Within the anode heel effect what is the difference of beam intensity?
If you had a body part that varies in thickness where would you place the cathode side of the tube?
When facing the table what side is the cathode on?

A
  • 45% difference of beam intensity from anode to cathode side
  • you would place the cathode side of the tube over the thickest part
  • when facing the table the cathode side is to your right
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57
Q 
function of the glass envelope is? 
what does it allow for? 
what is it made of?
A
  • the glass envelope maintains a vacuum inside the tube
  • it allows for x-rays to be produced and heat to be created
  • made of pyrex glass which is able to withstand the tremendous amount of heat generated.
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58
Q

what is the protective housing?
what is the purpose of the tube housing?
photons that escape the housing are referred to as?
to cool the tube it contains what kind of oil?
some may have what to cool?
what is the protective housing made of and lined with?

A
  • protective housing is the envelope of the x-ray tube that is encased in a protective housing or tube housing
  • the purpose of the tube housing is to control leakage radiation, isolate the high voltage, and cool the tube.
  • photons that escape the housing (except the port) are referred to as leakage radiation
  • to cool the tube it contains a dielectric oil
  • some units have a cooling fan
  • the protective housing is made of cast steel and lined with lead
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59
Q

what can cause tube malfunction?
what does the term blown tube refer to?
what is the most common cause of tube malfunction?
what does a gassy tube indicate?

A
  • moderate overloading of the tube- pitting/heavy overloading or failure of the rotating anode melting of anode- failure to preheat anode cracking of anode and excessive rotoring eventual thinning and breaking of the filament.
  • blown tube refers to a broken filament
  • blown tube is the most common cause of tube malfunction
  • gassy tube indicates the vacuum is compromised
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60
Q

what are the steps for x-ray production?

A
  1. rotor prep switch is depressed- filament heats up, space charge electron cloud is formed, and the rotating anode gets up to speed.
  2. the exposure switch is depressed- kVp is applied and placing a strong positive charge on the anode
  3. kinetic energy is transferred to the electrons- electrons accelerate toward the positive anode with tremendous velocity- negatively charged electrons are attracted to a positively charged anode.
  4. electrons strike the anode focal spot- electrons are suddenly slowed or stopped, and transfer their kinetic energy called target interactions
  5. after loosing all of its kinetic energy the electron continues on through the circuit
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61
Q

what is the target interaction?
what is % of kinetic energy converted to heat?
how much is converted to x-ray photons?

A
  • target interaction is the process of transferring electron kinetic energy to the target material
  • 99% of the incident electrons kinetic energy is converted to heat
  • less than 1% of incident electrons kinetic energy is converted to x-ray photons
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62
Q

what are the target interaction types?

the interaction that occurs depends on what?

A
  • bremsstrahlung interaction- aka braking or slowing and characteristic interactions
  • the interaction that occurs depends on the electron kinetic energy and the Eb energy of target energy shells
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63
Q

what x-ray is the most prevalent throughout the diagnostic range?

A

-bremsstrahlung x-ray is the most prevalent throughout the diagnostic range- only interaction up to 70kVp- incident electron interacts with the nuclear force field or directly impacts the nucleus- electrons come near the nucleus- or electrostatic force of the positive nucleus causes the negative electron to slow down and change its course- energy is lost and emitted as a photon/ Brems photon energy is exactly the difference between the entering and exiting electron kinetic energy

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64
Q

when does characteristic x-ray occur?

A
  • the characteristic x-ray occur when an incident electron interacts with a K shell electron and ejects it (ionization)
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65
Q

describe an atom using bohrs model and describe the subatomic particles

A

matter is composed atoms- atoms have 3 basic subatomic particles:
- protons +
- neutrons n0 (neutral)
- electrons -
the small dense nucleus is made up of protons and neutrons
electron shells contain orbital electrons- electrons are in constant motion around the nucleus in orbital shells
- the distance from the nucleus determines the energy of the shell-
- orbital shell closest to the nucleus is K it is the most binding

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66
Q

in a stable atom, what is the relationship between the number of protons and neutrons?

A

they are equal

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67
Q

what is “binding energy” what is its unit of measurement?

A

binding energy is the amount of energy needed to remove the electron from an atom
- it is measured in KeV

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68
Q

label electron orbital shells

A 
K- is the closest to the nucleus and it is the most binding
L-
M-
N-
O-
P
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69
Q

what is the relationship between electron orbital shell and the binding energy of electrons in that shell?

A

electron binding energy is the amount of energy needed to remove the electron from an atom-

  • as the number of protons increases so does the binding energy of a given electron
  • it takes more energy to remove a K shell electron than a shell farther away from the nucleus
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70
Q

shells closest to the nucleus have ___ electron binding energies- explain why?

A
  • stronger binding energies
  • due to the positive charges in the nucleus, atoms with high atomic # are bound more tightly than atoms with low atomic #’s
  • it takes more energy to remove a K shell electron than a shell farther away from the nucleus
  • as the atomic “ increases the K shell binding energy increases
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71
Q

what is the relationship between an atoms atomic number and electron binding energy?

A

as the atomic # increases the K shell binding energy increases

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72
Q

what are the types of energy and define?

A
  • mechanical- result of the action of machines or physical movement- includes potential energy (the capacity to do work (stored) and kinetic energy (energy in motion
  • chemical energy- energy released in a chemical reaction
  • heat/thermal energy- is the energy of motion at the molecular level
  • electrical energy- work done when electrons (negative particles) move through a wire (electrical charge)
  • nuclear energy- the energy contained in the nucleus of atom
  • eletromagnetic energy- electrical and magnetic disturbances in space
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73
Q

what are natural sources of electromaginetic energy

A
  • cosmic ray: particles that are emitted by the sun and stars
  • terrestrial radiation: emitted from deposits of uranium, thorium, and other radioactive substances found in the earth
  • radionuclides’s- radioactive nucleus- potassium-40 part of the human metabolism
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74
Q

what are x-rays

A

a form of man made electromagnetic energy created in an x-ray tube when high speed electrons are suddenly stopped

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75
Q

what is the difference between the wavelength frequency and energy of different types of EM energy?

A

frequency in the EM spectrum varies from very low frequency such as radio wave, to extremely high frequency such as gamma rays

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76
Q

as frequency increases, energy _____

A

increases

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77
Q

what is the velocity of all forms of EM energy?

A

velocity is the same for all forms of EM radiation- equal to the speed of light- 3x108 meters/ second in a vacuum

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78
Q

define and describe the “wave-particle duality of EM radioation”

A

when traveling through space, EM radiation behaves as a sine wave- when interacting with matter EM radiation behaves as a particle

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79
Q

explain where different forms of EM radiation fall on the EM spectrum

A 
- radio 10 (4)- 10 (2)
 microwave 1
infrared 10 (-2)
visible 10 (-5)
ultraviolet 10 (-5) 
x-ray 10 (-8)
gamma 10 (-10)
80
Q

explain the wave theory and how velocity, frequency and wavelength relate to each other

A
  • electromagnetic energy travels in forms of sine waves
  • wavelength- distance between 2 successive points- measured crest to crest or trough to trough
  • frequency- the number of waves that passes a given point in a given time frame- number of cycles per second
  • velocity is the same for all forms of EM radiation-
81
Q

who and when x-rays were discovered

A
  • x-rays were discovered by dr. wilhelm conrad rowntgen

- discovered on november 8, 1895

82
Q

what are the 12 properties of x-rays

A
83
Q

describe the characteristics of the x-ray table top

A
84
Q

describe different types of tube support systems

A
85
Q

define incoming line current and in what form is electricity supplied

A
86
Q

what is the purpose of the x-ray generator

A
87
Q

what are the two main divisions of the x-ray circuit and what is the function of each?

A
88
Q

what is a dead man exposure switch?

A
89
Q

what is the name and function of each device in the main x-ray circuit

A
90
Q

what occurs during each stage of a two stage exposure switch?

A
91
Q

what are the two types of timers and how do they know when to terminate the exposure?

A
92
Q

what is rectification and why is it necessary

A
93
Q

what is pulsating DC current

A
94
Q

what is pulsating DC current

A
95
Q

what is voltage ripple and how does it affect efficiency of x-ray production

A
96
Q

what is the function of the filament circuit

A
97
Q

what are the components of the filament circuit and what are their functions

A
98
Q

what is thermionic emission

A
99
Q

what controls thermionic emission?

A
100
Q

what are the 4 things needed to produce x-rays

A
101
Q

what 3 elements are provided by the physical components of the xray tube

A
102
Q

what 3 major components makes up the x-ray tube

A
103
Q

describe the cathode assembly

A
104
Q

what is a dual focus tube

A
105
Q

by looking at the control panel, how can you tell if your equipment has a dual focus tube

A
106
Q

describe the structure of the filaments

A
107
Q

what is vaporization

A
108
Q

what is the function of the filament and focusing cup

A
109
Q

by what process is the space charge cloud produced

A
110
Q

what causes the filament to become hot and boil off electrons

A
111
Q

what it the space charge cloud

A
112
Q

what does the mA setting on the operators panel control

A
113
Q

describe the focusing cup

A
114
Q

describe the anode assembly

A
115
Q

why do dx xray tubes use rotating anodes

A
116
Q

what are the 3 primary functions of the anode disc

A
117
Q

the focal track is made of what alloy

A
118
Q

what type of motor rotates the anode

A
119
Q

describe anode angle and what is mc in dx radiography

A
120
Q

what terms are used to refer to the specific spot on the anode that is struck by the electron stream and where x-ray photon are produced

A
121
Q

define actual and effective focal spot

A
122
Q

if the anode angle remains unchanged, how will the filament length affect the focal spot size?

A
123
Q

what are the pros / cons of a large and small focal spot

A
124
Q

what is the line focus principle

A
125
Q

what is the anode heel effect- what causes it- how can it be used to your advantage

A
126
Q

describe the envelope

A
127
Q

describe the protective housing including function and structure

A
128
Q

what are the mc tube malfunctions and their cause

A
129
Q

what is the most common cause of tube failure

A
130
Q

what is target interaction

A
131
Q

what element do target interactions occur with - what is the material of choice for the anode

A
132
Q

how much of the incident electron kinetic energy is converted to heat- x-ray photons

A
133
Q

what are the two interaction by which x-ray photons are produced- what tow factors determine which interaction will occur

A
134
Q

what is the only x-ray production interaction that can occur up to 70kVp- why

A
135
Q

describe x-ray production by a bremsstrahlung - brems- interaction

A
136
Q

what determine the x-ray energy of a photon produced by a brems interaction

A
137
Q

describe x-ray production by a characterisitc interaction

A
138
Q

why is characteristic x-ray production only possible at or above 70kVp

A
139
Q

what determine the x-ray energy of a photon produced by a characteristic interaction

A
140
Q

during characteristic s-ray production only electrons dropping in to the ____ shell will result in a dx x-ray photon- why?

A
141
Q

most x-rays are produced through which interaction

A
142
Q

film fog is due to

A

compton scatter

143
Q

when a proton strikes matter it will either?
what does attenuated mean?
attenuation occurs through a combination of?

A
  • it will either pass through without interaction- producing “good” IR exposure or be attenuated
  • attenuated is the reduction in the number of x-ray photons in the beam, and subsequent loss of energy- fewer photons exit the body then enter it.
  • attenuation occurs through a combination of photoelectric absorption and compton scatter
144
Q

what is differential absorption?

what does it result in?

A
  • various tissue types and volumes, absorb the beam differently
  • this results in image contrast and formation of the x-ray image
145
Q

what is the basic interaction that matter has with x-ray?

A
  • basic interactions include- photoelectric absorption, compton scattering, and coherent scattering
146
Q

what are the steps to photoelectric absorption?

A
  1. incident photon interacts with tightly bound inner shell electron of tissue atom and is completely absorbed
  2. x-ray photon is completely absorbed and not longer exists
  3. ejected electron leaves a vacancy in a inner shell
  4. an electron from a higher shell drops into the vacancy left in the lower shell
  5. this process will continue until the vacancy is in the outermost shell- this is called characteristic cascade
147
Q

what is the likelihood of photoelectric absorption?
it is more likely to occur as ? decreases?
when the x-ray photon interacts with?? high atomic number elements- what is result?
when the x-ray photon interacts with an inner shell electron- what is result?

A
  • more likely to occur as kVp decreases- lower photon energy
  • interacts with high atomic # elements the higher electron binding energies
  • interacts with an inner shell electron, higher electron binding energy
148
Q

describe compton scattering
what type of energy does a scattered photon have
what will stop a compton scattered photon from interacting?

A
  • incident photon strikes and ejects a loosely bound outer shell electron/ the remaining photon energy travels off in a random direction as a compton scattered photon
  • scattered photon has less energy than the original incident photon
  • compton scattered photon will continue to interact until it undergoes photoelectric absorption or exits the patient.
149
Q

what is the primary source of occupational exposure?
what happens if the compton scatter photon exits the patient and stikes the IR- film?
what is this called?
what does is decrease?
when is compton scatter more likely?

A
    • compton scatter is the primary source of occupational exposure
  • it it exits the patient and strikes the film it will cause unwanted radiographic density.
  • this is called radiation fog
  • it decreases visibility of detail
  • compton scatter is more likely as kVp increases and when the photon interacts with a loosely bound outer shell electron
150
Q

what are the AKA’s for coherent scattering?

what is the interaction of coherent scattering? describe?

A
  • AkA’s for coherent scattering are- classical, rayleigh, thomson scatter
  • the interaction between very low energy photon and matter- it is a very low energy photon striking an atom and scatters in a random direction, without loosing any energy
151
Q

what is the effect on technical factor selection?
during an exposure the majority of the beam is what?
how much of the beam transmits without interaction? what does it form?
during an exposure one of two things will occur- what are they?

A
  • during an exposure the majority of the beam is attenuated-
  • majority of the beam is attenuated
  • only a small percentage transmits without interaction to form the image.
  • during an exposure 1. x-ray transmit without interaction- this is called transmitted x-ray, remnant x-rays or exit radiation 2. attenuation- photoelectric absorption or compton scatter
152
Q

as kVp increases what increases and what decreases?
because compton scatter increases what does this result in?
as kVp decreases what decreases and what increases?
what type of image does this result iin?

A
  • as kVp increases- transmission increases and attenuation decreases, but of the interactions that do occur- more compton scatter and less photoelectric absorption
  • this compton scatter increases radiation fog which is bad- providing a lower contrast radiograph
  • as kVp decreases- attenuation increases and the interactions that do occur- more photoelectric absorption and less compton scatter
  • more photoelectric absorption results in less radiation fog and a high contrast radiograph (good)
153
Q

what would be the effect of scatter radiation?

A

fog

154
Q

how are x-rays produced?

A

x-ray are produced when high energy electricity produces high speed electrons that interact with matter (anode)

155
Q

what is electricity?

A

distribution and movement of electrons

156
Q

what is an electrical current?

A

pathway that permits electrons to move through resisting electrical devices and back to the source

157
Q

how do electrons move in a circuit?

A

the electrons move from the negative pole (source of electrons) and move toward the positive receiving pole.

158
Q

what are sources of XS electrons?

A

batteries, generators, solar converters, atomic reactors

159
Q

what are the factors used to describe electricity

A

of electron flowing, force of electron flow, opposition to the flow of electrons, direction of electron travel

160
Q

define amp/milliamp

A

unit of electric strength/current

161
Q

define volt

A

unit of force- strength of electron flow

162
Q

define ohms

A

unit of electrical resistance

163
Q

what is meant by AC or DC?

A

DC- electrons move in same direction all the time

AC - electrons first move in one direction then reverse and flow in the opposite direction

164
Q

4 things needed to produce x-ray

A

source- anode, accelerate, vacuum

165
Q

what 3 elements are provided by the physical componenets of the x-ray tube

A

source, anode, envelope

166
Q

what 3 major components make up the x-ray tube

A

cathode assembly, anode assembly, glass envelope

167
Q

describe the cathode assembly

A

filament and focusing cup- filament surrounded by the focusing cup - focusing cup- focuses the high speed electron stream across the tube toward the focal spot

168
Q

what is a dual focus tube

A

on the machine a long and short filament so that you can choose either a lg or sm focal spot
- gassy tube- the vacuum is compromised- vaporization of filament or anode or envelope gets cracked

169
Q

on control panel, how to tell if equipment has dual focus tube

A

you can select lg or sm focal spot not selecting filament- tells which filament will heat up - control how big of an area the electron stream hits by controlling the beam size

170
Q

describe filament

A

very thin and coiled wire- provides the source of electrons

171
Q

what is vaporization

A

filament gets hot and the metal vaporizes and causes the gassy tube

172
Q

function of filament and focusing cup

A

filament- provides source of electrons through thermionic transmission
focusing cup houses the filament narrows the thermionic cloud

173
Q

by what process is the space charge cloud produced?

A

the filament heats and electrons boil off producing the cloud- thermionic emission

174
Q

what causes the filament to become hot and boil off electrons

A

milliamperage- electricty

175
Q

what is the space charge cloud

A

electrons boiled off of filament

176
Q

what does the nA setting on the operators panel control

A

the current

177
Q

describe the focusing cup

A

anode disc, molybdenum stem, AC induction motor

178
Q

why do dx x-ray tubes use rotating anodes

A

heat dissipation

179
Q

what are the 3 primary functions of the anode disc?

A
180
Q

focal track is made of what alloy

A

tungsten- rhenium alloy- rhenium improves the elasticity

181
Q

what type of motor rotates the anode

A

AC induction motor it rotates the anode and dissipates the heat

182
Q

anode angle, and MC in dx readiography

A

angle of the target surface with response to the central ray in teh x-ray field, MC is 12

183
Q

terms are used to refer the specific spot on the anode that is struck by the electron stream and where x-ray photon are produced

A

actual focal spot- directed toward pt effective focal spot

184
Q

define actual and effective focal spot

A

actual focal spot- area on anode that the electron stream strikes during exposure and where photons are produces - effective focal spot- area of the focal spot projected out of the tube

185
Q

if anode angle is unchanged, how will the filament length affect the focal spot size

A

length of filament determines size of focal spot

186
Q

what are the pros and cons of a lg and sm focal spot

A

smaller focal spot- pro/ shorter filament- better resolution
con/ over heats filament- burn out the tube faster
larger focal spot- pro/ higher mA tech/ Con-produces images with decreased resolution

187
Q

what is the line focus principle

A

spread the heat out as much as possible while still getting the best recorded detail

188
Q

what is the anode heel effect- what causes it

A

when the x-ray beam intensity varies from anode to cathode. x-rays produced from the anode side of the tube must pass through eh heel of the anode- decreased number of photon- decreased intensity

189
Q

describe the envelope

A

maintain vacuum inside the tube- allows x-ray to be produced and heat to be created

190
Q

describe the protective housing including function and structure?

A

envelope encased in protective housing- made of cast steel, lined with lead, it controls leakage radiation, isolate high voltage, cool the tube

191
Q

what are the more common tube malfunctions and their cause

A

moderate overloading of the tube-pitting/ heavy overloading meliting of anode- failure to preheat anode- causes cracking of anode- XS rotoring eventual thinning and breaking of the filament- blown tube- broken filament- vacuum compromised

192
Q

what is the MC cause of tube failure?

A

blown tube

193
Q

what is target interaction

A

process of transferring e-kinetic energy to the target material

194
Q

what element do target interactions occur with?

A

tungsten

195
Q

how much of the incident electron kinetic energy is converted to heat? x-ray photon?

A

heat- 99%

XR photon- 1%

196
Q

what are the two interactions by which x-ray photons are produced? what two factors determine which interaction will occur?

A

bremsstrahlun interactions and characteristic interaction- depends on e-kinetic energy and electron energy of target energy shells

197
Q

what is the only x-ray production interaction that can occur up to 70kVp? and why?

A

bremsstrahlung

Trimester 7 (13 decks)

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