Radiology intro Flashcards
Who discovered x-ray? Where? When? What was the first radiograph taken of?
Wilhelm Conrad Roentgen, 1895 in Germany. Radiograph of his wife’s hand
Properties of x-ray..
Forms electromagnetic radiation, Causes ionisation, undetectable to human senses.
Basic production of x-ray
Electrons fired at atoms, creating kinetic energy resulting in electromagnetic radiation and heat. Then the x-ray photons are aimed at a subject
What does the atom consist of?
Protons and Neutrons (in the central nucleus) and Electrons (orbiting shells)
Atomic number (z) represents…
Number of protons
Mass number (A) represents…
Number of protons and neutrons
Isotopes and Radio-isotopes
Isotopes - same elements with different number of neutrons
Radio-isotopes are unstable that undergoes radioactive decay
What does the number of electron determine?
Chemical properties of an atom
“Ground state” is…
Neutral atom.
Number of electron = Number of protons
What is ionisation?
Ionisation is removing or addition of electrons to an atoms
Atom minus an electron is…
Positive ion (cation)
Atom added on with electron is…
Negative ion (anion)
What is the most inner shell labelled? and the other shells?
Innermost K - holds 2 electrons.
Then L - 8 electrons
Then M - 18 electrons
then N, O etc
What does binding energy depend on?
i) Which shell electron is in
ii) how many protons and neutrons are in the nucleus
Alpha particles radioactive emissions
2 protons and neutrons. Large, positive, extensive ionisation
Beta particles radioactive emissions
Electrons.
Small, negative, ionisation
Gamma particles radioactive emissions
Electromagnetic radiation, ionisation
When is ionisation a problem?
When it occurs in living cells. Causes DNA damage.
Indirect: produces free radicals that leads to DNA damage.
Electromagnetic radiation properties:
No mass, No charge, can travel in a vacuum
What is frequency?
Number of cycles per unit time. Measured in hertz, Hz/s
What is wavelength?
Distance travelled per cycle. Measured in metres, m
Formula for speed?
speed = frequency x wavelength
Flow of electric charge known as? .. measured in..?
Current. Measured in amps, A
How many direction current have?
Two.
Direct - unidirectional (batteries)
Alternative - reverses (mains)
What is voltage?
Difference in electrical potential between 2 points in electrical field
What is created when voltage applied to wire coil?
Electrons vibrate and create current
What is the result of the vibrating electrons produce heat and light?
Wire becomes hot and gives off light
Radiant heat causes movement of air molecules result in …
surrounding area becoming hot
What happens to wavelength when frequency increases?
Decreases (vice versa)
