Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS3 Radiology > X-Ray Production > Flashcards

X-Ray Production Flashcards

1
Q

where are the x-rays produced in a dental x-ray unit

A

tubehead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the function of the collimator

A

helps to direct the x-ray beam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the components of the x-ray tube

A

glass envelop
cathode (-ve cahrged)
anode (+ve charge)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the filament

A

coiled metal wire that has high current electricity passed through it and heats up and electrons are released from atoms in the wire by thermionic emission so a cloud of electrons forms around the cathode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the cathode filament made of

A

tungsten - has a high melting point, atomic number and is malleable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the cathode focusing cup

A

metal cup shaped around filament which is negatively charged and repels electrons released from the filament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the focusing cup made of

A

molybdenum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what occurs between the cathode and anode

A

the filament sits nearer the cathode and when electrons are produced they are repelled away from the negative cathode and are pushed very quickly to the positive anode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the measurement used when measuring electrons

A

electron volts (eV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the most important part of the anode

A

the target

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the function of the anode target

A

produces photons when bombarded with electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the important point on the anode target

A

the focal spot - which is a precise area on the target where electrons collide and x-rays are produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is situated around the target

A

heat dissipating block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the function of the heat dissipating block

A

when electrons collide with the target lots of heat is given off - it takes it away from the target to prevent damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the penumbra effect

A

blurring of the radiographic image due to focal spot not being a single point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how is the penumbra effect minimised

A

shrinking the size of the focal spot

17
Q

how can you shrink the size of the focal spot

A

using focal spot angulation

18
Q

what is a problem with focal spot angulation

A

lots of heat concentrated on small points - can overheat target and it will break

19
Q

what is the solution to the heat problem of focal spot angulation

A

use angled target - better heat tolerance as the electrons are spread over a larger area

20
Q

what holds the cathode and anode in place

A

glass envelop - helps to keep air out of the cathode and anode vacuum

21
Q

what is incorporated in the glass envelop

A

lead all over apart from where you want the photons to go

22
Q

what is filtration

A

removes lower energy (non-diagnostic) x-rays from the beam

23
Q

what is used for filtration

A

aluminium of adequate thickness

24
Q

what is the spacer cone

A

dictates the distance between focal spot of target and patient

25
Q

what size should the spacer cone be if the energy is less than 60kV

A

100mm

26
Q

what size should the spacer cone be if the energy is more than 60kV

A

200mm

27
Q

what are the three fates of x-ray photons that are emitted from the focal spot

A

stopped by the attenuation of lead shielding (in the glass envelop or from the tubehead itself)
stopped by the aluminium infiltration
exit tubehead to form x-ray beam

28
Q

what is the collimator function and structure

A

lead diaphragm attached to spacer cone which reduces patient dose by cropping x-ray beam to size and shape of x-ray receptor

29
Q

what size should the collimator be

A

50 mm x 40 mm

30
Q

what parts are incorporated in the control panel of an x-ray unit

A

on/ off switch
electronic timer
exposure time selector and presets
warning light and noise
kV selector

31
Q

what are the two consequences of electrons bombarding the target

A

heat production
x-ray production

32
Q

when do heat producing interactions occur

A

when bombarding electrons reach outer shell electrons and loses kinetic energy which is turned into heat energy

33
Q

what are the two x-ray producing interactions

A

continuous radiation interactions (majority)
characteristic radiation interactions

34
Q

what is continuous radiation

A

the bombarding electron passes close to the nucleus but avoids the electrons the nucleus slows down the electron and changes its direction - this lost kinetic energy is released as x-ray photons

35
Q

what is characteristic radiation

A

electron comes in and reacts with the inner shell electrons in tungsten atom and displaces it to a more peripheral shell or removes it completely
the remaining electrons reorganise themselves to fill innermost shells and this causes loss of energy which is emitted as photons specific energy

36
Q

what is photon energy equal to in characteristic radiation

A

the difference in the binding energies of the 2 shells involved

BDS3 Radiology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions