production of x rays

Question 1

what occurs at the cathode/filament?

Answer 1

it contains a very fine wire made of tungsten where a small current passes along 8-10mA

it has to go through a step down transformer because the supply which isd coming in is 13 amps

electrons become excited so the wire gets hot and may even give off light

electrons are lost from outer shell which causes an electron cloud to form over the cathode

Question 2

how is the electromagnetic spectrum divided

Answer 2

non - ionising and ionising radiation
longer wavelengths (radiowaves and microwaves) are non ionising, shorter wavelengths with higher energies such as x rays and gamma rays are ionising

Question 3

what is scattering?

Answer 3

a random change in direction of x ray photons after hitting something

Question 4

what is ionisation ?

Answer 4

removal of electrons to give electrons and positive ions

Question 5

what is absorption?

Answer 5

energy deposited into the tissue
represents dose of radiation which the patient recieves

Question 6

what is intensity

Answer 6

number of x ray photons in a defined area of the beam

Question 7

what is attenuation

Answer 7

reduction in intensity of x ray beam due to scattering and absorption

Question 8

what is penetration?

Answer 8

the ability of photons to pass through or into tissues/materials

Question 9

what are the characteristics of x rays

Answer 9

photons travel in a straight line (x ray photons form a divergent beam)
they can be absorbed
can be scattered
produce a latent image on film emulsion
cause ionisation
can cause biological damage

Question 10

what is the radiation dose?

Answer 10

the amount of radiation absorbed by the patient
low energy photons are often absorbed by soft tissues
DIFFERENT TO RADIATION EXPOSURE!