Intro Radiography Flashcards
What do xrays allow a view of?
Mineralised tissues
Who discovered xrays? And when?
Wilhelmina Conrad roentgen
1895
When were x Ray’s first used in dentistry?
1896
What does an atom contain?
Positive charged protons
No charge neutrons
Negative charged electrons
What does the nucleus contain?
Protons and neutrons
Where are electrons located?
Orbit nucleus in energy shells
How many is the maximum number of electrons for each shell?
K-2 L-8 M-18 N-32 O-50
What keeps electrons within shells?
Binding energy
What is required to removed electrons from an atom?
Energy
What is the atomic number?
Number of protons in nucleus
What is neutron number?
Number of neutrons in nucleus
What is the atomic mass number?
Atomic number + neutron number
What is an isotope?
Atoms with same atomic number
Different neutron number
What is a radioisotope?
Isotopes with unstable nuclei which undergo radioactive disintegration
Describe an alpha Particle
2 protons + 2 neutrons Large Positive charge Slow Penetrate 1-2 MM. In tissue Energy- 4-8 MeV Damage potential- extensive ionisation
Describe beta particles
Electrons Small Negative charge Penetrate 1-2 cm in tissue Energy- 100 kev- 6mev Damage potential- ionisation
Gamma rays
Electromagnetic radiation No size No charge Very fast Pass through tissue Damage potential- ionisation
What type of particles are similar to xrays used in dentistry?
Gamma rays
Energy levels less
What is energy measured in?
eV
What is frequency measured in ?
Hertz
What is wavelength measured in?
Metres or nano metres
At what speed do photons travel?
Speed of light - 186 282 miles per second
What is a radiograph?
A latent image cause by xrays passing through and object and causing physical change to crystals on the emulsion of a film
