Radiation Biology & X-ray Tubehead Key Terms Only Flashcards
Use this deck to study the terms for radiation and the creation of x-rays in the x-ray tubehead
absorption
- the total transfer of energy from the x-ray photon to the atoms of matter through which the x-ray beam passes
- depends on the energy of the x-ray beam and the composition of the absorbing matter or tissues
alpha particles
- a type of particulate radiation emitted from the nuclei of heavy metals
- contain two protons and two neutrons and are positively charged
aluminum disks
- disks or sheets of aluminum, usually 0.5mm thick, that are placed in path of the x-ray beam
- used to filter our the nonpenetrating, longer-wavelength x-rays
amperage
the number of electrons that pass through a conductor
the strength of an electrical current
ampere (A)
the unit of measure used to describe the number of electrons passing through a conductor * (electrical current strength)*
anode
- the positive electrode in the x-ray tube
- consists of a wafer-thin tungsten plate embedded in a solid copper rod
- converts electrons into x-ray photons
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
neutral atom
an atom that contains an equal number of protons and electrons
atomic number
the total number of protons in the nucleus, which is also equal to the number of electrons outside the nucleus
atomic weight / mass number
the total number of protons and neutrons in the nucleus of an atom
autotransformer
a voltage compensator that corrects for minor fluctuations in the current flowing through the x-ray machine
beta particles
fast-moving electrons emitted from the nucleus of radioactive atoms
binding energy / electrostatic force / binding force
- the attraction between the positive nucleus and the negative electrons that maintains electrons in their orbits
- determined by the distance between the nucleus and electrons
cathode
- the negative electrode in the x-ray tube
- consists of a tungsten wire filament in a molybdenum cup
- supplies the electrons necessary to generate x-rays
cathode ray
a stream of high-speed electrons that originate from the cathode in an x-ray tube
cell
the basic structural unit of living organisms
cell differentiation
individual characteristics of a cell that determine the response of the cell to radiation exposure
cell metabolism
the physical and chemical processes of a cell that determine the response of the cell to radiation exposure
central ray (CR)
the central portion of the primary beam of x-radiation
cephalostat
in extraoral imaging, a device that includes a receptor holder and head positioner that allow the dental radiographer to position both receptor and patient easily
circuit
a path of electrical current
filament circuit / low-voltage circuit
- the circuit that regulates the flow of electrical current to the filament of the x-ray tube
- controlled by the milliamperage settings
high-voltage circuit
- the circuit that provides the high voltage required to accelerate electrons and to generate x-rays in the x-ray tube
- controlled by the kilovoltage settings
- uses 65,000-100,000 volts
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 outer-shell electron
- no change in the atom occurs, and an x-ray photon of scattered radiation is produced
collimation
the restriction of the size and shape of the x-ray beam in order to reduce patient exposure
collimator / collimating device
a diaphragm, usually made of lead, used to restrict the size and shape of the x-ray beam
Compton electron
- an outer-shell electron that is ejected from its orbit during Compton scatter
- carries a negative charge
Compton scatter
one of the interactions of x-radiation with matter in which the x-ray photon collides with a loosely bound, outer-shell electron and gives up part of its energy to eject the electron from its orbit, causing the x-ray photon to lose its energy and continue in a different direction a lower energy level
control devices
- the components of the control panel of the x-ray machine that regulate the x-ray beam
- includes the timer, kilovoltage and milliamperage selectors
control panel
a part of the x-ray machine that contains an on/off switch and indicator light, an exposure button and indicator light, and control devices to regulate the x-ray beam
copper stem
a portion of the anode that dissipates heat away from the tungsten target
coulomb (C)
a unit of electrical charge
critical organ
an organ that, if damaged, diminishes the quality of an individual’s life
cumulative effects
the additive effects of repeated radiation exposure
cumulative occupational dose
the accumulated lifetime radiation dose for occupationally exposed workers
alternating current (AC)
a current in which electrons flow in opposite directions
direct current (DC)
a current in which electrons flow in one direction
digital image
an image composed of pixels
digital imaging
a system of filmless imaging used to capture an image using a sensor, breaking it into electronic pieces, and presenting and storing the image using a computer
dose
the amount of energy absorbed by a tissue
total dose
the quantity of radiation received, or the total amount of radiation energy absorbed
dose equivilent
a measurement used to compare the biologic effects of different types of radiation
dose rate
the rate at which exposure to radiation occurs and the absorption takes place (determined by dose/time)
dose-response curve
a curve that can be used to correlate the damage of tissues with the amount of radiation received
electrical current
the flow of electrons through a conductor to produce x-rays
electricity
- the energy used to make x-rays
- used as a source of power
electromagnetic spectrum
- the entire range of wavelengths of electromagnetic radiations
- extends from gamma rays (with the shortest wavelengths) to radio waves (with the longest wavelengths)
electron
a tiny, negatively charged particle found outside the nucleus in the atom
electron volt
the unit of measurement for the binding energy of orbital electrons
element
substances that make up only one type of an atom
energy
what occurs when matter is altered
exposure
a measure of ionization produced in air by x-radiation or gamma radiation
occupational exposure
contact with blood or other infectious materials involving the skin, eye, or mucous membranes that results from procedures performed by the dental professional
exposure button
a component of the dental x-ray machine control panel the activates the x-ray machine to produce x-rays
exposure factors
factors that influence the density of an image (ex: milliamperage, kilovoltage, exposure time)
exposure incident
a specific incident involving contact with blood or other potentially infectious materials that results from procedures performed by the dental professional
exposure light
a component of the dental x-ray machine control panel that provides a visible signal when x-rays are produced
exposure time
the interval during which x-rays are produced
extension arm
a part of the dental x-ray machine that suspends the x-ray tubehead and houses the electrical wires that extend from the control panel to the tubehead
extraoral imaging
an inspection of large areas of the skull or jaws that requires the use of extraoral imaging receptors
filament circuit
- regulates the flow of the electrical current to the filament of the x-ray tube using 3-5 volts
- controlled by the milliamperage settings
filtration
the use of absorbing materials (ex: aluminum) for removing low energy x-rays from the primary beam
added filtration
aluminum disks inserted in the dental x-ray machine between the x-ray tubehead seal and collimator to remove low-energy x-rays from the primary beam
inherent filtration
portions of the x-ray tubehead that serve to filter low-energy x-rays, including the glass window of the x-ray tube, the insulating oil, and the tubehead seal
total filtration
the combination of the inherent filtration and added filtration in an x-ray machine
focal spot
the tungsten target of the anode that converts bombarding electrons into x-ray photons, concentrating the electrons and creating an enormous amount of heat