rhs Flashcards
radiation
A form of energy carried by waves or a stream of particles
x-radiation
a high-energy radiation produced by the collision of a beam of electrons with a metal target in an x-ray tube
x-ray
A beam of energy that has the power to penetrate substances and record image shadows on receptors (photographic film or digital sensors)
Radiology
The science or study of radiation as used in medicine; a branch of medical science that deals with the therapeutic use of x-rays, radioactive substances, and other forms of radiant energy
Radiograph
an image or picture produced on a receptor (radiation-sensitive film, phosphor plate, or digital sensor) by exposure to ionizing radiation; a two-dimensional representation of a three-dimensional object
Dental radiograph
A photographic image produced on film by the passage of x-rays through teeth and related structures
Radiography
The art or science of making radiographs by the exposure of film to x-rays
Dental radiography
The production of radiographs of the teeth and adjacent structures by the exposure of an image receptor to x-rays
Dental radiographer
Any person who positions, exposes, and processes dental x-ray image receptors
Image
a picture or likeness of an object
Image receptor
A recording medium; examples include x-ray film, phosphor plate, or digital sensor
Dental imaging
the creation of digital, print, or film representations of anatomic structures for the purpose of diagnosis
What is one of the most important uses of dental images?
detection (of diseases and conditions that cannot be identified clinically)
Who discovered the X-ray?
Wilhelm Roentgen in 1895
X =
unknown
Fluorescence
a glow that results when a fluorescent substance is struck by light, cathode rays, or x-rays
Who built the first vacuum tube?
Heinrich Geissler in 1838
Hand mit Ringen ( hand with rings)
the first “medical” x-ray performed by Roentgen
Cathode rays
streams of electrons that are produced when a high voltage is applied to electrodes in an evacuated tube: (Johann Hittorf)
originate in an x-ray tube
Who made the first dental radiograph?
Otto Walkhoff, 1895
Describe the first hot-cathode x-ray tube
a high vacuum tube that contained a tungsten filamen
Who developed the first hot cathode x-ray tube?
William Coolidge,1913
the prototype for all modern x-ray tubes
What served as the precursor for all modern dental x-ray machines?
a mini version of the x-ray tube that was placed inside the head of an x-ray machine and immersed in oil
Do fast films require a short or long exposure time?
short, which reduces patient exposure to radiation
Bisecting technique
x-ray technique that applies the geometric principle in which the central ray bisects the angle formed by the dental film and the long axis of the tooth
Paralleling technique
x-ray technique, also known as the right-angle technique, whereby the film and tooth and PID are parallel
Bite-wing technique
Also known as the interproximal technique is used to examine the interproximal surfaces of teeth.
What extraoral technique is most used often in dentistry?
panoramic radiography
Panoramic radiograph
shows all of the structures in both dental arches in a single film
Commonly known as a panorex
What does digital imaging allow for?
instant and easy transmission of images and electronic storage
reduces patient exposure to radiation and chemical waste
what do atoms consist of?
a central nucleus and orbiting electrons
what is the identity of an atom determined by?
the composition of its nucleus and the arrangement of its orbiting electrons
electrons
Tiny, negatively charged particles that have very little mass
what is the nucleus composed of?
protons and neutrons
occupies very little space in the atom
protons carry
positive electrical charges
neutrons carry
no electrical charge
atomic weight is determined by?
the number of protons and neutrons in the nucleus
atomic number
the number of protons inside the nucleus = the number of electrons outside the nucleus
Which shell is located closest to the nucleus and has the highest energy level?
K shell
elements
substances made up of only one type of atom
the binding energies of orbital electrons are measured in?
electron volts (eV) or kilo electron volts (keV)
molecules are formed by
the transfer of electrons OR by the sharing of electrons between the outermost shells of atoms
ion
an atom that gains or loses an electron and becomes electrically unbalanced
Ionization
the process of converting an atom into ions
what does ionization deal with?
electrons; requires sufficient energy to overcome the electrostatic force that binds the electron to the nucleus
what is the results in an ion pair?
when an electron is removed from an atom in the ionization process
the atom becomes the – ion and the ejected electron becomes the — ion
positive, negative
Radioactivity
the process by which certain unstable atoms or elements undergo spontaneous disintegration, or decay, in an effort to attain a more balanced nuclear state
T/F: in dentistry radiation/x-radiation is used, not radioactivity
True
Ionization radiation
radiaition that is capable of producing ions by removing or adding an electron to an atom
Particulate radiation
tiny particles of matter that possess mass and travel in straight lines and at high speeds
Which type of energy do particulate radiations transmit?
kinetic energy
by means of their extremely fast-moving, small masses
four types of particulate radiations
alpha particle, electron (beta & cathode rays), protons, and neutrons
alpha particle
emitted from the nuclei of heavy metals and exist as two protons and neutrons, without electrons
electromagnetic radiation
the propagation of wavelike energy (without mass) through space and matter
the energy propogated is followed by oscillating electric & magnetic fie
T/F: Electromagnetic raditions are machine made and occur unnaturally
false; man made and occur naturally
what are examples of electromagnetic radiations?
gamma rays, x-rays, visible light, microwaves, radiowaves
electromagnetic spectrum
electromagnetic radiations arranged according to their energies
do all energies of the electromagnetic spectrum share common characteristics?
yes!
T/F: only high energy radiations are capable of ionization
True
ie. gamma rays and x-rays
Particle concept
characterized electromagnetic radiations as discrete bundles of energy called photons or quanta
Photons
bundles of energy with no mass or weight that travel as waves at the speed of light and move through space in a straight line “carrying the energy” of electromagnetic radiation
Wave concept
characterizes electromagnetic radiations as waves and focuses on the properties of velocity, wavelength, and frequency
velocity
speed of the wave
travels as waves as the speed of light in a vaccum
wavelength
the distance between the crest of one wave and the crest of the next
determines the energy and penetrating power of the radiation
the shorter the distance between the crests,
the shorter the wavelength and the higher the energy and ability to penetrate matter
wavelength is measured in?
nanometers (nm; 1 x 10^-9) for short waves and meters (m) for longer waves
frequency
the number of wavelengths that pass a given point in a certain amount of time
T/F: frequency and waves are inversely related
True
if the freq of the wave is high, the wavelength will be short & vice ver
What does diagnostic radiography use?
high frequency, shorter waves
properties of x-rays: appearance
x-rays are invisible
properties of x-rays: mass
x-rays have no mass or weight
properties of x-rays: charge
x-rays have no charge
properties of x-rays: speed
x-rays travel at the speed of light
properties of x-rays: wavelength
x-rays travel in waves and have short wavelengths with a high frequency
properties of x-rays: path of travel
x-rays travel in straight lines and can be deflected, or scattered
properties of x-rays: focusing capability
x-rays cannot be focused to a point and always diverge from a point
properties of x-rays: penetrating power
x-rays can penetrate liquids, solids, and gases
the composition of the substance determines whether x-rays penetrate or
properties of x-rays: absorption
x-rays are absorbed by matter; the absorption depends on the atomic structure of matter and the wavelength of the x-ray
properties of x-rays: ionization capability
x-rays interact with materials they penetrate and cause ionization
properties of x-rays: fluorescence capabality
x-rays can cause certain substances to fluorescence or emit radiation in longer wavelengths (ie. visible light and ultra violet light)
properties of x-rays: effect on receptor
x-rays can produce an image on a receptor
properties of x-rays: effect on living tissues
x-rays can cause biologic changes in living cells
component parts of a dental x-ray machine
control panel, extension arm, and tubehead
control panel contains
an on-off switch, indicator light(2), exposure button, and control devices to regulate the x-ray beam
extension arm contains
suspends the x-ray tubehead and houses the electrical wires that extend from the control panel to the tubehead
allows for movement and positioning of the tubehead
