Fundamentals of Radiologic Theory Flashcards
What year were x-rays discovered, and by whom? What was the first this he x-ray’d?
Discovered by Wilhelm Conrad Roentgen in 1895. Took x-ray of wifes hand
Who produced the first dental radiograph and in what year?
Dr. Otto Walkhoff in 1895
Who produced the first intra oral radiograph?
Dr. Edmund Kells
Who created the first dental x-ray unit? What mistakes did he make?
William Rollins. Burnt his hand which led to interest in radiation protection
Who developed the first hot cathode x-ray tube which was the prototype for all modern x-ray units?
William Coolidge
What advancement was made in 1933 to x-ray units?
Oil was added to the tube to control heat
What year did Kodak develop pre-wrapped film?
1913
Who developed the bisecting technique?
Weston Price
Who else worked on bisecting and also developed the bitewing technique?
Riley Raper
Who were the three men who developed and worked on PT?
Dr. Edmund Kells, Franklin McCormack, Dr. Fitzgerald
Who did the first pano?
Hisatugu Numata in 1933
What happens when photons interact with material?
Ionization
What kind of charge do photons have?
No charge
What speed to rays move at?
186,000 miles per second
What is wavelength?
Distance from the crest of one wave to the crest of the next wave
What units are wavelengths measured in?
Angstrom units
1/1000,000,000cm
What is the range of length of x-ray wavelengths used in diagnostic radiography?
0.1 to 0.5 Angstrom
What does longer wavelength mean
Lower frequency, less energy, less ability to penetrate matter
Weaker- not for dental
What does shorter wavelength mean?
Higher frequency, more energy, greater ability to penetrate matter
More ideal for dental
What does frequency mean?
The number of crest passing a fixed point per second
When are x-rays produced?
When subatomic particles interact with atoms
2 Major parts of atoms
Centrally located nucleus
Electrons orbiting around the nucleus
Which atom has the simplest arrangement?
Hydrogen Atom
WHat does the nucleus consist of?
Positively charged protons
Neutrons
How many protons and electrons are in a neutral atom?
Same number of protons and electrons
What is ionization?
The production of ion pairs by the removal of an electron from an atom of the matter which is struck by the x-rays
One or more electrons are removed from their orbit/shell
WHat happens to an atom when it becomes ionized?
It loses its electrical neutrality and becomes positively charged
Called a positive ion
Why do we need to understand ionization?
We need to understand the therapeutic and harmful effects x-radiation can have on tissues. They can alter or destroy cells
If too many cells are destroyed, normal function of tissue can be altered
What happens when H2O in the body’s tissues becomes ionized?
Causes the atomic structure to be altered to H2O2 (hydrogen peroxide)
Causes local tissue damage
What are the two types of ionizing radiation?
Particulate and Electromagnetic
WHat is the major difference in the way x-rays and light affect photo-magnetic plates?
Radiation can penetrate opaque objects
What are the three sets of terms used for units of radiation that are being phased out?
Roentgen, RAD and REM
Which terms used for units of radiation are gaining greater acceptance?
The INternational System:
- Coulombs per KG replaces Roentgen
- Gray replaces RAD
- Sievert replaces REM
What are the 3 quantities used for x-ray protection measurement?
Exposure
Absorbed dose
Dose equivalent
What is exposure? What units are used?
Measurement of ionization in air produced by x-rays or gamma rays
Coulomb/Kg/Roentgen
What is absorbed dose? What units are used?
Amount of energy deposited in any form of matter by any type of radiation
gray (Gy) & RAD are used
What is dose equivalent? What units are used?
Term used for radiation protection purpose to compare biological effects of various types of radiation
Sievert (Sv)/ REM
What units are used to measure all radiation?
Grays/RADs and Sieverts/REMs
