Absorption is the transformation of the energy of radiation (x-rays) into another form.
Alloy is a composition of two or more metals.
Angiogram is a picture of one or more blood vessels which are filled with X-ray dye.
Atomic Number is the number of protons in the nucleus.
(This is equal to the number of electrons in orbit around the nucleus in
a neutral atom.
Background radiation refers to the low intensity
radiation due to cosmic rays and naturally occuring radioactive
material.
Barium This is a chalky liquid which outlines various parts of the digestive tract on an X-ray. It is inert and is not absorbed by the body. A patient may drink it to enable an x-ray study of their esophagus, stomach or small intestine.
Bremsstrahlung is electromagnetic radiation (usually
x-rays) produced by the rapid deceleration of an electron which passes
close to a nucleus (translates as "braking radiation").
Casting is the process of shaping molten metals in a
mould.
CAT scan This is short for Computer Assisted
Tomography. This technique uses X-rays to generate computerized images
(pictures) of all parts of the body. The technique can create
three-dimensional pictures. (Sometimes referred to as CT scan, for
Computer Tomography).
Cathode rays are electrons emitted from the negatively charged plate in a discharge tube.
Cathode Ray Tube is a vacuum tube which allows the direct observation of cathode rays (e.g. a television tube).
Compton Effect is the reduction in energy of a photon, as a result of its interaction with an electron.
Contrast A substance which is apaque to x-rays, used during an X-ray examination. It can be given orally or intravenously (by injection).
Crystal is a solid material whose atoms are arranged in a precise pattern.
Crystallography is the study of the structure of crystals.
Diffraction is the spreading of a wave after passing
through a gap of comparable dimensions to the wavelength of the wave
Discharge tube is a partially evacuated tube in which
electrons travel whenever a suitable voltage is applied between the
electrodes in the tube.
Elastic scattering is the result of elastic collisions
where the particles which collide do not lose energy due to the
collisions.
Electromagnetic waves are caused by the acceleration of
charged particles. These waves involve electric and magnetic fields
vibrating transversely and sinusoidally at right angles to the direction
that the wave is travelling. The waves do not require a medium for
propogation and travel through a vacuum at 300 million meters per
second.
Dose the amount of energy deposited per unit mass.
Electron is a tiny particle which has negative charge.
Film badges contain photographic film and are usually
worn by workers who are in regular contact with ionizing radiation. The
badge indicates the extent of their exposure to ionising radiation.
Fluorescent materials are those which emit light when
radiation strikes them.
Frequency is the number of oscillations (cycles) per
second (measured in hertz).
Glancing angle is the angle between a ray and the
reflecting surface.
Hard X-rays are those of high frequency and therefore
high penetrating ability.
Hertz (Hz) is a unit of frequency; equal to one
oscillation per second.
Induction Coil is a device for producing high voltages from low
voltage direct current, using electromagnetic induction.
Intensity is the amount of energy passing through unit area
normal to the direction of the wave.
Ion is a charged atom
Ionisation is the process of forming ions
(It often involves the removing of electrons from atoms).
Ionization chamber is a device for measuring the amount
of ionizing radiation.
Ionizing radiation has sufficient energy to interact
with atoms and remove electrons from their orbits, causing the atom to
become charged or "ionized."
Irradiated means exposed to radiation.
KE is Kinetic Energy which is the energy a body has by
virtue of its motion.
keV is a kilo-electron Volt (1000 electron volts) and
is a measure of energy applicable to sub-atomic particles.
Lattice is a regular network of fixed points about
which the atoms or molecules vibrate in a crystal.
Linear Accelerator is a collection of cylindrical
electrodes used to accelerate charged particles to high energies.
Mammogram is an X-ray of the breast. It is used to
detect breast cancer and other abnormalities of the breast.
MeV is a million electron volts.
Monochromatic one colour (i.e. waves of a single
wavelength i.e. of a single frequency)
Mutation refers to a change in the chemical
constitution of the chromosomes of an organism.
Nanometer is ten to the power of minus nine of a meter
(one millionth of a milli-meter).
Nucleus is the positively charged core of an atom.
Opaque means not permitting certain types of wave
motion to pass through.
Pair Production refers to the creation of an electron
and a positron as a result of a photon of radiation passing close to a
nucleus.
PE is Potential Energy which is the energy a body has
by virtue of its position.
Photodiode is a semiconductor component whose
conductivity is modulated by the absorption of light.
Photoelectric effect is the emission of electrons from
the surface of a metal when light of sufficiently short wavelength is
incident on the metal.
Photons may be thought of as bundles of energy. The
amount of energy in a photon is proportional to the frequency of the
radiation.
Polarized radiation is where the electric and magnetic
oscillations are confined to one plane (rather than three-dimensional).
Positron is a particle with the same mass as an
electron but with a positive charge (equal in magnitude to that of an
electron).
Quantum Mechanics is the branch of physics that
interprets physical phenomena occuring on a very small scale (e.g. the
motion of electrons).
Radiation is defined as the emission and propagation of
energy in the form of rays, waves or particles through a medium.
Examples include radio waves, microwaves, visible light, ultraviolet,
x-rays and cosmic rays.
Radiation dose is the amount of energy deposited per
unit mass of matter.
Radiation therapy This is where large doses of X-rays
are used to treat cancer by killing cancer cells.
Radioactivity is the spontaneous disintegration of the
nucleus of certain elements with the consequent emission of radiation.
(The chemical nature of the original atom is changed in the process).
Radiologist A doctor who interprets X-ray images to
diagnose disease.
Radiology In general, "radiology" refers to medical
imaging techniques that allow doctors to see inside a patient's body.
Although the word "radiology" implies radiation, not all of the
techniques actually use radiation.
Refract means that a ray changes direction as it passes
from one medium to another of different density.
Scan This is a term used to describe the computerized
images (pictures) generated by computer assisted tomography.
Sievert is the SI unit of dose equivalent being that
arising when the absorbed dose of ionising radiation is one Joule per
kilogram.
Soft X-rays are those of relatively low frequency and
therefore low penetrating ability.
Spectrometer is an instrument used for measuring the
wavelength of radiation.
Spectrum is a display of colours (as in the rainbow).
It may also refer to a distribution of radiation after it has been
diffracted.
Thermionic emission is the emission of electrons from
the surface of a metal when the metal is heated.
Tomography is a technique for using x-rays for
photographing one specific plane of the body, for diagnostic purposes.
Tungsten is a metal with atomic number 74 and a melting
point of 3410 C.
Vacuum Pump reduces the pressure of a gas in a
container by extracting some of the gas.
Voltage is a measure (in volts) of the potential
difference between two parts of an electrical circuit.
Wave is a transmission of energy.
Wavelength is the distance between two successive
crests.
Weld is a joining of two metal surfaces by heating
sufficiently to melt them together.