Chapters 1-2: Radiation History & Radiation Physics Flashcards
Ionization, X-Radiation, X-ray Machine, Dental X-ray Production
List the two types of electrical circuits used in the production of x-rays.
- filament circuit / low-voltage circuit
- high-voltage circuit
Define the term: photoelectric effect
- one of the interactions of x-radiation with matter in which the x-ray photon collides with a tightly-bound, inner-shell electron and gives up all its energy to eject the electron from its orbit
- all of the energy of the photon is absorbed by the displaced electron in the form of kinetic energy
What component of the tubehead surrounds and protects the x-ray tube with insulating oil?
the metal housing
Define the term: ion
- an electrically unbalanced particle
- an atom that gains or loses an electron
How is voltage measured in the production of x-rays?
kilovoltage (kVp)
What is the term for the electrical current when the electrons flow in one steady, constant direction through the conductor?
direct current (DC)
Define the term: image
a picture or likeness of an object
What component of the anode in the x-ray tube us used to dissipate the heat away from the tungsten target during the production of x-ray photons?
the copper stem
List the two parts of an atom
- nucleus
- electrons in orbit
Which type of x-radiation is the most detrimental to humans?
scatter radiation
Describe the process of the electrical current in a step-down transformer.
- the primary/input coil contains more wire coils that receive and energize the alternating electrical current
- this induces an electrical current in the secondary/output coil that contains less wire coils
- the resulting electrical current is directed in the x-ray tube
Define the term: x-ray
a beam of energy that has the power to penetrate substances and record image shadows on image receptors
What is the particle concept of electromagnetic radiations?
electromagnetic radiations are discrete bundles of energy with no mass or weight that travel in waves at the speed of light in a straight line
Why would a substance be considered radioactive?
if it gives off energy in the form of particles or rays as a result of the disintegration of the atomic nuclei
What charges are present in a neutral atom?
an equal number of protons (positive charges) and electrons (negative charges)
What is the term for the path of an electrical current?
circuit
What percentage of Compton scatter occurs in dental radiography?
62%
How many volts are used in the high-voltage circuit?
65,000-100,000 V
How many volts are used in the filament circuit?
3-5 V
What is considered “the heart” of the x-ray generating system?
the x-ray tube
What forms when atoms are combined?
molecules
What is the wave concept of electromagnetic radiation?
electromagnetic radiations are waves that travel in various wavelengths at the speed of light
Which component of the cathode in the x-ray tube produces electrons when heated?
tungsten filament
Is the cathode in the x-ray tube positively or negatively charged?
negatively charged
What is radiography the science of?
the art and science of making radiographs by the exposure of an image receptor to x-rays
Describe the speed of x-rays.
X-rays travel at the speed of light
Define the term: dental radiograph
a photographic image produced on an image receptor by the passage of x-rays through teeth and related structures
What is the term used to measure the speed of a wave?
velocity
Define the term: element
substances made up of only one type of atom
Are frequency and wavelength conversely or inversely related?
conversely (if the frequency of the wave is high, the wavelength will be short, and vice versa)
How is the atomic number of an atom determined?
by the number of protons inside the nucleus, which equals the number of electrons outside the nucleus
List the four types of particulate radiation.
- electrons (beta particles or cathode rays)
- alpha particles
- protons
- neutrons
Define the term: beta particles
fast-moving electrons emitted from the nucleus of radioactive atoms
What is the conversion of alternating to direct current of electricity?
rectificatoin
What are placed in the in the x-ray tubehead to filter out the nonpenetrating, longer-wavelength x-rays from the exiting x-ray beam?
aluminum disks
What is the purpose of a step-up transformer?
to increase the voltage from the incoming 110-220 line voltage to the necessary 65,000-100,000 V used by the high-voltage circuit
Define the term: nucleus
the dense core of the atom, composed of protons and neutrons
How do electrons travel inside an atom?
in well-defined paths called orbits or shells
What is the purpose of an autotransformer?
a voltage compensator that automatically corrects minor fluctuations in the electrical current
Define the term: dental imaging
the creation of digital, print, or film representations of anatomic structures for the purpose of diagnosis
Describe the fluorescence capabilities of x-rays.
X-rays can cause certain substances to fluoresce or emit radiation in longer wavelengths
List the two concepts of that describe how electromagnetic radiations move through space.
- particle concept
- wave concept
What electrical charge do neutrons carry?
- no electrical charge
- they are neutral
Approximately how much of the x-ray energy produced at the anode is considered general radiation?
approximately 70%
What component of the anode in the x-ray tube serves as a focal spot for the bombarding electrons from the cathode, which will then convert those electrons into x-ray photons?
the tungsten target
Define the term: scatter radiation
a form of secondary radiation that is caused by an x-ray beam being deflected from its path by its interaction with matter
List the two components of the anode in the x-ray tube.
- tungsten target
- copper stem
What component of the x-ray tubehead aims and shapes the exiting x-ray beam?
the position-indicating device (PID)
Define the term: secondary radiation
x-radiation that is created when the primary beam interacts with matter
Describe the penetrating power of x-rays.
X-rays can penetrate liquids, solids, and gases, depending on the composition of that substance
What occurs when matter is altered?
energy
Where is the beginning of the electricity needed to generate x-rays created?
when the x-ray machine is turned on, the electrical current enters the control panel from the wall outlet
How are electromagnetic radiations arranged?
according to their energies on the electromagnetic spectrum
Define the term: coherent scatter / unmodified scatter
- one of the interactions of x-radiation with matter in which the path of a low-energy x-ray photon interacts with an outershell electron
- no change in the atom occurs
- scatter radiation is produced
What occurs when the x-rays produced inside the tube are directed to exit the tubehead?
- the leaded-glass housing prevents the x-rays from escaping in all directions and allows a small number to pass through
- the x-rays travel travel through th tubehead seal and the aluminum disks filter out the longer wavelengths from the x-ray beam
- the lead collimator restricts the size of the x-ray beam
- the remaining x-ray beam travels down the position-indicating device and exit at the opening of the tubehead
What component of the x-ray tubehead alters the voltage of the incoming electricity?
the transformer
What component of the x-ray tubehead seals in the insulating oil and filters out the x-ray beam?
the tubehead seal
Describe the appearance of x-rays.
X-rays are invisible
Define the term: ionization
- the production of ions
- the process of converting an atom into an ion, resulting in the formation of a positive atom and a dislodged negative electron
What are particulate radiations?
tiny particles of matter that possess mass and travel in straight lines at high speeds to create kinetic energy
Do shorter wavelengths carry more or less penetrating power?
more penetrating power
What determines the energy and penetrating power of the radiation?
wavelength
Define the term: molecule
two or more atoms joined together by chemical bonds
Which circuit in the x-ray tube is controlled by the milliamperage settings?
the filament circuit
Describe the wavelength of x-rays.
X-rays travel in waves and have short wavelengths with a high frequency
Describe the absorption properties of x-rays.
X-rays are absorbed by matter, depending on the atomic structure of that matter and the wavelength of the x-ray
Explain the difference between radiology and radiography.
- radiology is the overall branch of medicine that studies the uses of radiation in medicine
- radiography is the science of making physical radiographs by exposing x-rays
Define the term: mass number / atomic weight
the number of protons and neutrons in the nucleus of an atom
List the three types of transformers used to adjust the electrical current during the production of x-rays.
- step-down transformer
- step-up transformer
- autotransformer
Describe the mass of x-rays.
X-rays have no mass
Define the term: wavelengths
the distance between the crest of one wave and the crest of the next
Define the term: frequency
the number of wavelengths that pass a given point in a certain amount of time
Define the term: general radiation / braking radiation / bremsstrahlung radiation
a form of radiation that occurs when speeding electrons slow down because of their interactions with the tungsten target in the anode
What occurs within the x-ray tube when the exposure button is pushed?
- the high-voltage circuit is activated
- the electrons in the cathode are accelerated across the x-ray tube to the molybdenum cup in the anode
- the electrons are directed in a narrow beam to the tungsten target and are converted into x-ray energy and heat
- the heat is absorbed by the copper stem and insulating oil
- the remaining x-rays are directed into the x-ray tubehead
During the ionization process, what is the result of an ion pair?
- when an electron is removed from the atom
- the atom becomes the positive ion
- the ejected electron becomes the negative ion
Describe the effect of x-rays on an image receptor.
X-rays can produce an image on an image receptor
When electrons are being converted into x-rays, how much is converted into x-ray energy and heat?
- 1% x-rays
- 99% heat
Do longer wavelengths carry more or less penetrating power?
less penetrating power
What is the purpose of a step-down transformer?
to decrease the voltage from the incoming 110-220 line voltage to the necessary 3-5 V used by the filament circuit
What is the term for the energy used to make x-rays?
electricity
From the following, which is the only radiation to be created in the x-ray tube?
1. alpha particles
2. beta particles
3. cathode rays
4. protons
5. neutrons
cathode rays (the rest originate in the nucleus of an atom)
List some of the uses/benefits of dental images.
- to detect lesions, diseases, and conditions of the teeth and surrounding structures that cannot be seen clinically
- to confirm or classify suspected diseases
- to localize lesions or foreign objects
- to provide information during dental procedures
- to evaluate growth and development
- to illustrate the changes of caries, disease, and trauma
- to document the condition of a patient at a specific point in time
- to aid in the development of a clinical treatment plan
What is the difference between the wire coils of a step-up transformer and a step-down transformer?
the wire coils in a step-up transformer have more coils in the secondary/output coil than in the primary/input coil
Define the term: characteristic radiation
a form of radiation that occurs when a high-speed electron dislodges an inner-shell electron from an atom, causing ionization of th atom
Define the term: image receptor
a recording medium (ex: film, phosphor plates, digital sensors)
What are the two ways that molecules can be formed?
- by the transfer of electrons
- by the sharing of electrons between the outermost shells of an atom
How are electrons maintained in their orbit inside the atom?
by electrostatic force (the attraction between the positive nucleus and the negative electrons)
What three events can occur after the x-ray beam exits the tubehead and arrives at the patient?
- the x-rays can pass through the patient with no interaction
- the x-rays can be completely absorbed by the patient
- the x-rays can be scattered
Define the term: Compton electron / recoil electron
- an outer-shell electron that is ejected from its orbit during Compton scatter
- carries a negative charge
List the two groups of ionizing radiation.
- particulate radiation
- electromagnetic radiation
List the four possibilities of x-ray photon interaction with matter.
- no interaction
- absorption/photoelectric effect
- Compton scatter
- coherent scatter
What type of x-radiation interaction occurs most in scatter radiation?
Compton effect
Is the anode in the x-ray tube positively or negatively charged?
positively charged
What is placed over the opening of the metal housing in the x-ray tubehead to restrict the size of the exiting x-ray beam?
the lead collimator
List the two components of the cathode in the x-ray tube.
- tungsten filament
- molybdenum cup
Describe the effect of x-rays on living tissues.
X-rays can cause biologic changes in living cells
Define the term: radiation
a form of energy carried by waves or a stream of particles
Which has more penetrating power- primary or secondary radiation?
primary radiation
Describe the path of travel of x-rays.
X-rays travel in straight lines, but can be deflected/scattered
During the production of x-rays, what is considered a self-rectifier to alter the current of electricity?
the x-ray tube
Cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared light, radar waves, microwaves, and radio waves are all examples of what time of ionizing radiation?
electromagnetic radiation
List the two types of radiation created by the conversion of the electron’s kinetic energy into x-ray photons.
- general radiation / braking radiation / bremsstrahlung radiation
- characteristic radiation
What are the two measurements used to determine the binding energy?
- electron volts (eV)
- kilo electron volts **(keV) **
What is the purpose of the anode in the x-ray tube?
to convert the bombarding electrons from the cathode into x-ray photons that will exit the x-ray tubehead
What is found on the control panel of the x-ray machine?
- on-off switch and its indicator light
- exposure button and its indicator light
- control devices (exposure time, kilovoltage, milliamperage settings)
Fill in the blank: A radiograph is a ______-dimensional representation of three-dimensional object
A radiograph is a two -dimensional representation of a three-dimensional object
What is the term for the electrical current when the electrons flow in two, opposite directions?
alternating current (AC)
What part of the dental x-ray machine produces the x-rays?
the x-ray tubehead
When and where does thermionic emission occur in the production of x-rays?
when the electrons pass through and heat the tungsten filament in the cathode
What is the term for the measurement of the number of electrons moving through a conductor?
amperage (A)
What is the term for the measurement of force that causes electrons to move from the negative cathode to the positive anode in the x-ray tube?
voltage volts = V
What is the fundamental unit of matter?
the atom
Define the term: radiograph
an image or picture produced on an image receptor (ex: digital sensor, phosphor plate) by exposure to ionizing radiation
Define the term: x-radiation
a high-energy radiation produced by the collision of a beam of electrons with a metal target in an x-ray tube
Which component of the cathode in the x-ray tube focuses the electrons into a narrow beam to direct them toward the anode?
the molybdenum cup
Describe the focusing capability of x-rays.
X-rays cannot be focused to a point and will always diverge from a point
Define the term: ionizing radiation
radiation that is capable of producing ions by removing or adding an electron to an atom
What suspends the x-ray tubehead from the control panel?
the extension arm
How is current measured in the production of x-rays?
milliamperage (mA)
Define the term: Compton scatter
- one of the interactions of x-radiation with matter in which the x-ray photon collides with a loosely-bound, outershell electron and gives up part of its energy to eject the electron from its orbit
- the x-ray photon loses energy and continues in a different direction at a lower energy level
Describe the charge of x-rays.
X-rays have no charge
What percentage of interactions of the dental x-ray beam with matter account for the photoelectrical effect?
30%
Who is a dental radiographer?
any person who positions, exposes, and processes dental x-ray image receptors
Which circuit in the x-ray tube is controlled by the kilovoltage settings?
the high-voltage circuit
What device is used to increase or decrease the voltage in an electrical current?
a transformer
Define the term: electromagnetic radiation
the propagation of wavelike energy (without mass) through space or matter
Define the term: cathode rays
streams of high-speed electrons that originate in an x-ray tube
Is general or characteristic radiation more common in the conversion of electrons to x-ray photons?
general radiation
What type of ionizing radiation are x-rays?
electromagnetic radiation
Define the term: absorption
the total transfer of energy from the x-ray photon to the atoms of matter through which the x-ray beam passes
What electrical charge do protons carry?
positive charge
What prevents overheating in the metal housing of the tubehead by absorbing the heat that is created during x-ray production?
insulating oil
What does x-radiation absorption depend on?
- the energy of the x-ray beam
- the composition of the absorbing matter
What is radiology the study of?
the science or study of radiation as used in medicine
In dentistry, is radiation or radioactivity used?
radiation
Define the term: matter
anything that occupies space and has mass
Define the term: radioactivity
Why is it important that the x-ray tube rectifies the electrical current to a direct current during the production of x-rays?
direct current creates a smooth, steady supply power that will produce similar x-rays that will reduce the patient’s exposure to radiation
Define the term: electrical current
the flow of electrons through a conductor to create electricity
Define the term: binding energy / binding force
the attraction between the positive nucleus and the negative electrons that maintains electrons in their orbits
What is the purpose of the cathode in the x-ray tube?
to produce and supply the electrons necessary to generate x-rays
Define the term: dental radiography
the production of radiographs of the teeth and surrounding structures by the exposure of an image receptor to x-rays
List the two electron classifications in particulate radiation.
- beta particles
- cathode rays
Define the term: primary radiation / primary beam / useful beam
the penetrating x-ray beam that is produced at the target of the anode and that exits the tubehead
What electrical charge do electrons carry?
negative
What component of the x-ray tube prevents generated x-rays from escaping in all directions?
the leaded-glass housing
