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Rad Theory > Chapter 1 Importance Of Radiographs > Flashcards

Chapter 1 Importance Of Radiographs Flashcards

1
Q

RADIATION HISTORY

A

• Radiology is a method of recording images of dental structures by the use of x-rays
• X-rays were first discovered by Dr. Wilhelm Conrad
Roentgen on November 8, 1895 in Wurzberg, Bavaria
• In his honour, x-rays are often referred to as Roentgen Rays

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2
Q

W.C Roentgen

A

Discovered x-rays

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3
Q

Dr. Otto Walkoff

A

First dental radiograph

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4
Q

Dr. Edmund Kells

A

First dental radiograph in United States
Living patient 1896

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5
Q

First pre wrapped intra oral radiographs

A

• By 1913, the Eastman Kodak Company manufactured the first pre-wrapped intraoral radiographic films

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6
Q

Who introduced Bisecting technique

A

• Weston Price, a Cleveland dentist, introduced the bisecting technique in 1904
• Howard Riley Raper redefined the original bisecting technique and introduced the bitewing technique in 1925 also wrote first text in 1913

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7
Q

Who applied parallel technique in dental

A

Franklin W. McCormack in 1920 applied the paralleling technique in dental

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8
Q

F.Gordon Fitzgerald

A

•F. Gordon Fitzgerald, the “father of modern dental radiography” reviewed interest in the paralleling technique with the introduction of the long-cone paralleling technique in
1947

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9
Q

RADIATION

A

RADIATION
• A form of energy carried by waves or stream of particles

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10
Q

XRadiation

A

X-RADIATION
• A high-energy radiation produced by the collision of a beam of electrons with a metal target in an x-ray tube

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11
Q

X-ray

A

X-RAY
• A beam of energy that has the power to penetrate substances and record image shadows on photographic film
X-RAY
• Weightless bundle of energy (x-ray photon)
• Possess particles of waves and particles
• Invisible and cannot be detected by any of the senses
• Possess no mass, no weight, no charge
• Travel at the speed of light
• Possess short wavelengths and high frequency
X-RAY
• Travel in straight lines and can be deflected or scattered
• Absorbed by matter
• Interact with materials they penetrate and cause ionization
• Produce an image on photographic film
• Cause biological transformations in living cells

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12
Q

Radiology

A

RADIOLOGY
• The study or science of radiation that deals with the use of x-rays, radioactive substances, and other forms of radiant energy in the diagnosis and treatment of disease

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13
Q

Radiograph

A

RADIOGRAPH (RADIOGRAM)
A picture that is, a visible photographic record on a film produced by the passage of x-rays through an object or body

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14
Q

Dental Radiography

A

DENTAL RADIOGRAPHY
• The making of radiographs of the teeth and adjacent structures by the exposure of film to x-rays

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15
Q

Dental radiographer

A

DENTAL RADIOGRAPHER
• Any person who positions, exposes, and processes dental x-ray film

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16
Q

Matter

A

MATTER
• Anything that occupies space and has mass
• When matter is altered, energy results
• All matter is composed of atoms

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17
Q

Atom

A

ATOM
• A tiny, invisible particle that is the fundamental unit of matter
• The smallest part of an element that has the properties of that element
ATOMIC STRUCTURE
ATOM
• An atom consists of 2 parts: a central nucleus and orbital electrons
• At present, 118 different atoms have been identified
• Hydrogen - simplest atom (atomic number = 1)
• Atoms are arranged in increasing atomic number on a chart known at the “PERIODIC TABLE OFTHE ELEMENTS”

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18
Q

Nucleus

A

NUCLEUS
• The core of the atom
• Composed of protons (positively charged particles) and neutrons (neutrally charged particles ie: no electrical charge)
• The nucleus of an atom occupies very little space
• Most of the atom is empty space
• Ex: atom = football stadium nucleus = football

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19
Q

Electrons

A

ELECTRONS
• Tiny negatively charged particles that have very little mass
• The arrangement of electrons and neutrons in an atom resembles that of a miniature solar system
• Electrons travel around the nucleus in orbtis or shells like the planets revolve around the sun
ORBITS / SHELLS
• An atom contains a maximum of 7 shells
• The shells or orbits are designated with the letters K L M NO P Q
• The K shell is located closest to the nucleus and has the highest energy level
• Each shell has a maximum number of electrons it can hold

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20
Q

Strongest Binding energy

A

BINDING ENERGY / BINDING FORCE
• Electrostatic force or attraction between the positive nucleus and the negative electrons
• Determined by the distance between the nucleus and the orbiting
electron
• It is different for each shell
• The strongest binding energy is found closest to the nucleus in the
K-shell

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21
Q

Molecules

A

• Molecules are atoms that bond together in different ways; atoms are joined by chemical bonds
• Molecules can be formed by the transfer of electrons, or by the sharing of electrons
b
• Like the atom, a molecule is a tiny invisible particle
• Sometimes there are 2 or more atoms; other times there may be thousands
• When 1 atom of oxygen bonds with 2 atoms of hydrogen, it forms a water molecule Eg: H20 (simplest molecule)

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22
Q

Ionization

A

IONIZATION
• Production of ions, or the process of converting an atom into
ions
• Deals only with electrons and requires sufficient energy to overcome the electrostatic force that binds the electron to the nucleus

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23
Q

Ion

A

ION
• An ion is an atom or molecule which has lost or gained one or more electrons, making it positively or negatively charged.

24
Q

IONIZING RADIATION

A

IONIZING RADIATION
• Radiation that is capable of producing ions by removing or adding an
electron to an atom
2 CLASSIFICATIONS:
• PARTICULATE RADIATION
• ELECTROMAGNETIC RADIATION

25
Q

PARTICULATE RADIATION

A

• Tiny particles of matter
• Possesses mass
• Travels in straight lines at high speeds
• Transmits kinetic energy
BETA PARTICLES
• Fast moving electrons emitting from the nucleus
CATHODE RAY
• Stream of high speed electrons originating in an x-ray tube
ALPHA PARTICLES
• Protons and neutrons emitting from the nuclei of heavy metals

26
Q

ELECTROMAGNETIC RADIATION

A

• Radiation that is manmade or occurs naturally
• Possesses no mass, no weight, and no electrical charge
• Travels at the speed of light (186,000 miles/ second
• Travels as both a particle and a wave; therefore, both concepts are considered
• Propagates electric fields at right angles to the path of travel
• Possesses different measurable energies ie: frequencies and wavelengths

27
Q

Wave lengths
Electromagnetic Radiation

A

Determines energy and penetrating power of radiation
• Measured in nanometers = short wavelengths
• Measured in meters = long wavelengths
• The shorter the distance between the crests, the shorter the wavelength and higher the energy and ability to penetrate matter

28
Q

Electromagnetic radiation
Frequency

A

FREQUENCY
• Number of wavelengths that pass a given point in a certain amount of time
• Frequency and Wavelength are inversely related
• High frequency=short wavelength
• Short frequency=long wavelength
• Low frequency radiation= long wavelength=less energy
• High frequency radiation=short wavelength=more energy

29
Q

X-RAY MACHINE

A
30
Q

Tube head

A

• Where x-rays are produced
• Sealed glass bulb (envelope) similar to a glass envelope of an ordinary light bulb except this envelope has lead incorporated into it
• Inside the tube, all the air has been pumped out to create a VACCUM
• It is immersed in an OIL bath which provides electrical insulation and helps to dispense HEAT caused by the generation of x-rays

31
Q

TUBE HEAD

A
32
Q

CATHODE

A

CATHODE
• Negative charge terminal
• Tungsten filament wire (coil) is attached to the cathode pole

33
Q

Where is tungsten filament embedded

A

• The tungsten filament wire is embedded in the MOLYBDENUM CUP (Focusing Cup) which is responsible for directing the electrons to the tungsten target of the anode
• When the tube head is in operation, an electric current passes through the coil heating it to INCANDESCENCE ie: the coil becomes white with the generation of heat (glowing with heat)

34
Q

Thermionic Emission

A

CATHODE
• This causes the release (emittance) or “boiling off” of electrons from the heated tungsten filament which is known as
THERMIONIC EMISSION
• Dr. William D. Coolidge invented the thermionic emission tube in
1913
• The design of the coolidge tube eliminated the need for gas to create electrons, replacing gas with an incandescence

35
Q

Anode

A

• Positive charge terminal
D
• Mostly made up of copper COPPER ROD
• Copper like oil is used to dissipate heat
• Certain materials such as aluminum, silver, and copper are excellent conductors of current, whereas materials such as glass or plastic conduct poorly and are often used as insulators
• The tungsten target is attached to the copper stem
• The speeding electrons hit the tungsten target; the target measures about 1mm x 1.5 mm

36
Q

Collimate

A

COLLIMATOR
• Lead plate with a central hole that fits directly over the opening of the metal housing where the x-rays exit
• It restricts the size of the x-ray beam (7cm = 2.75”)

37
Q

FILTER

A

• Made up of aluminum
• 1.5 to 2.5 mm in thickness
• Filters out long wavelengths with poor penetration power

38
Q

Milliamperage (ma)

A

MILLIAMPERAGE (mA)
• Ampere is the unit of measurement for the electrical current
• Milliampere seconds (mAs) refers to the total QUANTITY of x-rays produced ie: it controls the amount or quantity of the electric current entering the x-ray machine as well as the heat of the filament wire
• The hotter the filament wire, the more electrons created ie: the greater the electron cloud
• It also controls or determines the amount of FILM BLACKENING ie: the higher the mA, the darker the x-ray
• Range: 7mA to 15mA

39
Q

Kilovoltage (kVp)

A

• It controls the SPEED of the electrons when traveling from the CATHODE to the ANODE as well as the WAVELENGTH
• The speed of the electrons, in turn, determines the PENETRATING POWER of the x-rays produced

40
Q

KILOVOLTAGE PEAK (KVP)

A

• When the voltage is increased, the electrons travel faster and produce hard radiation and are able to penetrate most dense structures producing a high quality picture kVp and penetrating power are DIRECTLY related
• Ex: as kVp increases, penetrating power increases
• Range: 50 - 100 kVp

41
Q

TIMER

A

TIMER
• Regulates the length of time that the current will pass through the x-ray tube
• The length of time needed to expose the film adequately will vary from patient to patient ie: for children, the exposure time is decreased by 1/3, and for edentulous patients, the exposure time is decreased by ¼
• The timer, like mA dial controls FILM BLACKENING (DENSITY)

42
Q

Exp time is effected by

A

Exposure Time is affected by:
a) Radiographic Technique
b) Type of x-ray film
c) Tissues being radiographed
d) Target film distance

43
Q

Alternating Current (AC)

A

• The cathode and the anode are connected with high voltage to move electrons at a very high speed.
• The voltage is about 1000 times more than what comes out from a 110-volt wall outlet

44
Q

Step down transformer

A

STEP-DOWNTRANSFORMER
• Decreases the voltage from the incoming 110- 220- line voltage to 3-5 volts used by the filament circuit
• Has more wire coils in the primary coil than in the secondary coil
• The coil that receives the alternating electrical current is the primary (input) coil; the secondary coil is the output coil

45
Q

Step up transformers

A

• Increases the voltage from the incoming 110: 220- line voltage to 65,000-100,000 volts used by the high voltage cireuit
• Has more wire coils in the secondary coil than in the primary coil

46
Q

Autotransformer

A

AUTOTRANSFORMER
• Serves as a voltage compensator
• It corrects for minor fluctuations in the current

47
Q

Bremstrahlung Radiation

A

BREMSTRAHLUNG RADIATION
• Sudden stopping or “braking” of high speed electrons when they hit the tungsten target in the anode

48
Q

General Radiation

A

GENERAL RADIATION
• Occurs when an electron hits the nucleus or comes close to the nucleus of the tungsten atom
•When an electron comes close to the nucleus, it is attracted to the nucleus and slows down resulting in an x-ray photon of LOWER energy
• Consists of many different energies and wavelengths

49
Q

Characteristics Radiation

A

• CHARACTERISTIC RADIATION
• Produced when a high speed electron dislodges an inner shell electron from the tungsten atom and causes IONIZATION
• The remaining orbiting electrons are rearranged to fill the vacancy
• Accounts for a small part of x-ray production

50
Q

Primary and Secondary Radiation

A

PRIMARY & SECONDARY RADIATION
• PRIMARY RADIATION
• X-ray beam that is produced at the target of the anode and exits the tubehead
• Referred to as the primary or useful beam

• SECONDARY RADIATION
• X-radiation that is created when primary beam interacts with matter ex: soft tissues of head, cranial bones and teeth
• Less penetrating than primary radiation

51
Q

SCATTER & LEAKAGE RADIATION

A

SCATTER & LEAKAGE RADIATION
SCATTER RADIATION
• A form of secondary radiation
• A result of an x-ray photon deflected in all directions traveling to all parts of the client’s body and to all areas of the operatory
• Detrimental to client and radiographer
LEAKAGE RADIATION
• Occurs if the x-ray tubehead is not properly sealed and lead lined

52
Q

ENERGY ABSORPTION &
PHOTOELECTRIC EFFECT

A

• Absorption depends upon the energy of the x-ray beam
• Absorption occurs as a result of “photoelectric” effect
• IONIZATION takes place in photoelectric effect ie: an x-ray photon collides with an inner shell electron giving up all its energy to eject the electron from its orbit
• ‘The ejected electron is known as a PHOTOELECTRON possessing a negative charge with minimal penetrating power
• The remaining atom has a positive charge
• Photoelectric effect accounts for 30% of x-ray production

53
Q

COMPTON SCATTER

A

• Evidence of ionization
• X-ray photon collides with outer shell electron and gives up part of its energy to eject the electron from its orbit
• X-ray photon looses energy traveling in a different direction at a lower energy level
• The new, weaker x-ray photon interacts with other atoms until all of its energy is gone
•Ejected electron is known as COMPTON or RECOIL electron possessing a negative charge
• Accounts for 62% of the scatter that occurs in radiography

54
Q

COHERENT SCATTER

A

• UNMODIFIED SCATTER
• Occurs when a low energy x-ray photon interacts with an
outer shell electron
• Results in no change in the atom
• X-ray photon of scattered radiation is produced
• No evidence of ionization
• X-ray photon is “unmodified” ie: it undergoes a change in direction without a change in energy
• Accounts for only 8% of x-radiation :

55
Q

Compton scatter

A
56
Q

COHERENT SCATTER

A

Rad Theory (12 decks)

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