Chapter 3: Electromagnetic Energy Flashcards
Irradiated
Referring to matter that intercepts radiation and absors part or all of it; exposed.
Nucleus
Center of a living cell; spherical mass of protoplasm that contains the genetic material (DNA) that is stored in its molecular structure.
Center of an atom that contains neutrons and protons.
Quantum Theory
Theory in the physics of matter smaller than an atom and of electromagnetic radiation.
Quantum An x-ray photon.
Unit
Standard of measurement
Rectification
Process of converting alternating current to direct current.
Electromagnetic Energy
Type of energy in x-rays, radio waves, microwaves, and visible light.
Substance
Any drug, chemical or biologic entity.
Atom
Smallest particle of an element that cannot be divided or broken by chemical means.
Transmission
Passage of an x-ray beam through an anatomical part with no interaction with atomic structures.
Ionizing Radiation
Radiation capable of ionization.
Infrared light
Light that consists of photons with wavelengths longer than those of visible light but shorter than those of microwaves.
Nucleon
A proton or a neutron.
Useful Beam
Primary radiation used to form an image.
Wavelength
Distance between similar points on a sine wave; the length of one cycle.
Radiopaque
Referring to a tissue or material that absorbs x-rays and appears bright on a radiograph.
Speed
Term used to loosely describe the sensitivity of film to x-rays.
Law of conservation of matter
Principle that states that matter can be neither created nor destroyed.
Field
Interactions among different energies, forces, or masses that cannot be seen nut can be described mathematically.
Reduction
Process by which an electron is given up by a chemical to neutralize a positive ion.
X-ray imaging system
X-ray system designed for radiography, tomography, or fluoroscopy.
Output
Process of transferring the results of a computation from primary memory to storage or to the user.
Electromagnetic Spectrum
Continuum of electromagnetic energy.
Force
That which changes the motion of an object, a push or a pull. Expressed in newtons (N).
Visible light
Radiant energy in the electromagnetic spectrum that is visible to the human eye.
Radiolucent
Referring to a tissue or material that transmits x-rays and appears dark on a radiograph.
Attenuation
Reduction in radiation intensity that results from absorption and scattering.
Frequency
Number of cycles or wavelengths of a simple harmonic motion per unit time.
Expressed in Hertz (Hz).
1 Hz = 1 cycle/s.
Conductor
Material that allows heat or electric current to flow.
Tissue
Collection of cells of similar structure and function.
Electromagnetic Radiation
Oscillating electric and magnetic fields that travel in a vacuum with the velocity of light.
Includes x-rays, gamma rays, and some nonionizing radiation (such as ultraviolet, visible, infrared and radio waves)
Velocity
Rate of change of an object(s) position over time; speed.
The velocity of all electromagnetic radiation is 3 x 10^8 m/s.
Electron
Elementary particle with one negative charge.
Electrons surround the positively charged nucleus and determine the chemical properties of the atom.
Reflection
Return or reentry of an x-ray.
Mass
A quantity of matter; expressed in kilograms.
Wave theory
Theory that electromagnetic energy travels through space in the form of waves.
Window
Thin secton of a glass envelope through which the useful beam emerges.
Spectrum
Graphic representation of the range over which a quantity extends.
Element
Atoms that have the same atomic number and the same chemical properties.
Substance that cannot be reduced further without changing its chemical properties.
Wave equation
Formula that states that velocity equals frequency multiplied by wavelength.
Refraction
Deviation of course that occurs when photons of visible light traveling in straight lines pass from one transparent medium to another.
Volt
SI unit of electric potential and potential difference.
Translucent
Surface that allows light to be transmitted but greatly alters and reduces its intensity.
Opaque
Surface that does NOT allow the passage of light.
Joule
Unit of energy
The work done when a force of 1 N acts on an object along a distance of 1 m.
Weight
Force on a mass that is caused by the acceleration of gravity.
Properly expressed in newtons (N), but commonly expressed in pounds. (lbs) 4.4lb = 1N.
Microwave
Short-wavelength radiofrequency.
Absorption
Transfer of energy from an electromagnetic field to matter; removal of x-rays from a beam via the photoelectric effect.
Process by which ultrasound transfers energy to tissue through conversion of acoustic.
Sine wave
Variation in the movement of photons in electrical and magnetic fields.
Electric Field
Lines of force exerted on charged ions in the tissues by the electrodes that cause charged particles to move from one pole to another.
Pair production
Interaction between the x-ray and the nuclear electric field that causes the x-ray to disappear and that causes two electrons 1 positive and 1 negative to take its place.
Wave-particle duality
Principle that states that both wave and particle concepts must be retained, because wave-like properties are exhibitied in some experiments and particle-like properties are exhibited in others.
Electron Volt
Unit of energy equal to that which an electron acquires from a potential difference of 1 V.
Matter
Anything that occupies space and has form or shape.
Hertz
Unit of frequency; the number of cycles or oscillations that occur each second during simple harmonic motion.
Magnitude
Number that represents a quantity.
Planck’s Constant
Fundamental physical constant that relates the energy of radiation to its frequency.
Origin
Point at which two axes meet on a graph.
Electric Current
Flow of electrons
Energy
Ability to do work ; measured in joules (J).
Ultraviolet light
Light that is located at the short end of the electromagnetic spectrum between visible light and ionizing x-rays.
It is beyond the range of human vision.
Sinusoidal
Simple motion; a sine wave.
Work
Product of the force on an object and the distance over which the force acts.
Expressed in joules (J).
W = F x d
Square law
Principle that states that one can compensate for a change in the source - to - object distance by changing the mAs by the factor SID squared.
Amplitude
Width of a waveform
Amplitude is 1/2 the range from crest to valley over which the sine wave varies.
Orgrans
Collection of tissues of similar structure and function.
Law of conservation of energy
Principle that states that energy may be transformed from one form to another but cannot be created or destroyed; the total amount of energy is constant.
Field of view
Image matrix size provided by digital x-ray imaging systems.
Photon
Electromagnetic radiation that has neither mass nor electric charge but interacts with matter as though it is a particle.
X-rays and gamma rays
Photons interact with matter most easily when the matter is approximately the same size as the photon wavelength.
X-Rays behave as though they are particles.
Visible light behaves like a wave.
Emulsion
Material with which x-rays or light photons from screens interact and transfer information.
Radiofrequency
Electromagnetic radiation with frequencies from 0.3 kHz to 300 GHz ; Magnetic resonance imaging uses RF in the range of approximately 1 to 100 mHz.
Transparent
Surface that allows light to be transmitted almost unaltered.
Crookes tube
Forerunner of modern fluorescent, neon, and x-ray tubes.
Inverse square law
Law that states that the intensity of radiation at a location is inversely proportional to the square of its distance from the source of radiation.
Inverse Square Law Pt 2
X-rays / Gamma Rays
The only difference between x-rays and gamma rays is their origin.
Visible light is identified by wavelength, radiofrequency is identified by frequency, and x-rays are identified by energy.
