intro to radiology Flashcards
what is a radiograph?
an image produced by x-rays passing through and object and interacting with the photographic emulsion on a film
why are X-rays used in dentistry?
teeth are mineralised tissues- different parts of the tooth will absorb differing amounts of radiation
caries=demineralisation=radiolucent
enamel-highly mineralised=radiopaque
when was the first x-ray taken in dentistry?
1896
what is the nucleus of an atom made up of?
protons (+) and neutrons (no charge)
what charge does the nucleus of an atom have?
positive
what is the nucleus of an atom surrounded by?
electron shells
what do electron shells contain?
diff numbers of electrons that allow an atom to remain stable?
what electron shell is closest to the nucleus?
K
how many electrons do K and L energy shells have?
K-2
L-8
can electrons exist between shells?
no- this is the forbidden zone
they can only move between shells if binding energy is overcome
what is the atomic number of atoms?
Z- the number of protons in the nucleus
what is the atomic mass number?
A-number of protons + no of neutrons
what is an isotope?
same atomic number- but diff number of neutrons
what is an ion?
a charged atom/molecule
if there are more electrons than protons in an ion it is known as ?
an anion
if there are more protons than electrons it is known as?
a cation
what determines the chemical properties of an atom?
electrons
an atom in its ground state is known as what?
neutral- number of electrons is the same as number of protons
removing and adding electrons to an atom is known as what?
ionisation
an atom that has lost an electron is known as what?
a cation- a positive ion
an atom that has gained an electron is known as what?
an anion- a negative ion
do electrons closest to the nucleus have more or less energy than those further away from the nucleus?
less energy than those further away
when is ionisation a problem?
when it occurs in living cells
-can cause damage to tissue
-can damage DNA leading to cancer/tumours
describe the order of electromagnetic spectrum?
radiowaves
microwaves
infrared
visible light
UV
X-rays
gamma rays
what has longest wavelength and what has the shortest?
longest=radiowaves
shortest=gamma waves
what part of spectrum has most and least energy?
least-radiowaves
most-gamma rays
what does the electromagnetic spectrum describe?
the types of electromagnetic radiation
what is electromagnetic radiation?
a stream of photons (energy)
what are examples of ionising radiation?
UV
x rays
gamma rays
what causes ionising radiation?
high energy photons cause ionisation of atoms- releasing chemicals and cause DNA damage
what is needed for electrons to move through a current?
voltage (potential difference)
are x-rays involved in radioactive decay?
no- only alpha, beta and gamma
what are X-rays very similar to?
gamma
are x rays fast or slow?
fast
do x rays cause ionisation?
yes
do X-rays have a weight, mass or charge?
no
do x rays have the same energy values as gamma rays?
no- they are lower
define the voltage?
the power that causes a current to flow or electrons to move from cathode to anode
what is needed for electricity to flow?
a circuit
