Radiology

Question 1

how are x rays and gamma rays similar

Answer 1

both have high frequencies –> high energy

very short wavelength

Question 2

why is it bad to have shorter wavelengths

Answer 2

greater potential of damage to cells –> higher energy

Question 3

what determines energy of photons

Answer 3

potential difference

Question 4

what increase photon energy

Answer 4

increase pd

Question 5

which photons more likely absorbed by patients

Answer 5

lower energy

Question 6

which photons more likely pass through patients

Answer 6

higher energy

Question 7

what current determines how many photons produced

Answer 7

current

larger current –> photons more likely to reach sensor

Question 8

what does aluminium filter do

Answer 8

low energy photons absorbed by filter

higher energy photons reach patients

Question 9

what does rectangular collimation do

Answer 9

reduce dose up to 50%
reduce damage to patients
reduce amount radiation exposure to patients
by changing shape of x-ray beam

Question 10

what is radiopaque

Answer 10

white, enamel

Question 11

what is radiolucent

Answer 11

black

Question 12

what are 2 mechanisms of damage

Answer 12

direct + indirect

Question 13

how does direct mechanism cause damage

Answer 13

mutations to DNA due to damage to bonds between nucleic acids
more dangerous

Question 14

how does indirect mechanism cause damage

Answer 14

radiolysis of water moles - makes free radicals

more likely

Question 15

what are the 3 harmful effects

Answer 15

somatic deterministic
somatic non-deterministic
genetic non-deterministic

Question 16

what is somatic deterministic

Answer 16

if dose greater than threshold dose

then damage always occurs

Question 17

what is somatic non-deterministic

Answer 17

no threshold dose
results DNA mutations
leads to cancer
very low possibility

Question 18

what are 5 effects radiology has on salivary glands

Answer 18

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

Question 19

what is amount of background radiation and where does it come from

Answer 19

2.7mSv per annum

sun, plants, radon gas

Question 20

what is daily dose of radiation

Answer 20

7.4 microSv

Question 21

what is flight distance

Answer 21

quantity of radiation

Question 22

what is radiation absorbed dose

Answer 22

amount energy absorbed from radiation beam per unit mass of tissue

Question 23

what is effective dose

Answer 23

tissue weighting factor
how sensitive each tissue is to radiation
high number = more sensitivity
breast tissue + salivary glands

Question 24

what is dose of radiograph with parotid glands

Answer 24

16-24microSv

Question 25

what is dose of radiograph without parotid glands

Answer 25

7-14 microSv

Question 26

what is the dose for intramural film

Answer 26

0.3-21.6 microSv

Question 27

what 6 equipment dose reduction techniques are there

Answer 27

focus to skin distance less than 20cm
alternating current
aluminium filtration - photons absorbed to reduce dose
rectangular collimation
pd increases, - darker image
current + time can alter dose