Radiology Flashcards
how are x rays and gamma rays similar
both have high frequencies –> high energy
very short wavelength
why is it bad to have shorter wavelengths
greater potential of damage to cells –> higher energy
what determines energy of photons
potential difference
what increase photon energy
increase pd
which photons more likely absorbed by patients
lower energy
which photons more likely pass through patients
higher energy
what current determines how many photons produced
current
larger current –> photons more likely to reach sensor
what does aluminium filter do
low energy photons absorbed by filter
higher energy photons reach patients
what does rectangular collimation do
reduce dose up to 50%
reduce damage to patients
reduce amount radiation exposure to patients
by changing shape of x-ray beam
what is radiopaque
white, enamel
what is radiolucent
black
what are 2 mechanisms of damage
direct + indirect
how does direct mechanism cause damage
mutations to DNA due to damage to bonds between nucleic acids
more dangerous
how does indirect mechanism cause damage
radiolysis of water moles - makes free radicals
more likely
what are the 3 harmful effects
somatic deterministic
somatic non-deterministic
genetic non-deterministic
what is somatic deterministic
if dose greater than threshold dose
then damage always occurs
what is somatic non-deterministic
no threshold dose
results DNA mutations
leads to cancer
very low possibility
what are 5 effects radiology has on salivary glands
salivary gland tissue has low turnover rate
damage take 6 months to manifest
slow to repair
damage takes long time to occur + resolution also long
salivary glands most sensitive tissue – absorbs large amount of radiation
what is amount of background radiation and where does it come from
2.7mSv per annum
sun, plants, radon gas
what is daily dose of radiation
7.4 microSv
what is flight distance
quantity of radiation
what is radiation absorbed dose
amount energy absorbed from radiation beam per unit mass of tissue
what is effective dose
tissue weighting factor
how sensitive each tissue is to radiation
high number = more sensitivity
breast tissue + salivary glands
what is dose of radiograph with parotid glands
16-24microSv
