Brainscape's Knowledge GenomeTM

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


See full index

BDS3 RADIOLOGY > 4 - Biological effects of ionising radiation > Flashcards

4 - Biological effects of ionising radiation Flashcards

1
Q

Describe an alpha particle.

A
  • 2 protons, 2 neutrons
  • large particle, travels a few inches
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe a beta particle.

A
  • electron
  • small, travels a few feet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe a gamma ray.

A
  • EM radiation
  • high energy, travels long distances
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe x-rays.

A
  • high or low energy
  • travel long distances
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is ionising radiation?

A

Radiation that has enough energy to knock an electron out of an atoms electron shell, making it an ion

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

How much energy is deposited into matter when it is ionised?

A

35 eV

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

How much energy is involved in atomic bonds?

A

4 eV

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

Define direct damage to DNA.

A

Radiation interacts with atoms of the DNA molecule or another important part of the cell

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

Define indirect damage to DNA.

A

Radiation interacts with the water in the cell, producing hydroxyl free radicals which damage the DNA

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

What type of radiation typically causes double strand damage?

A

Alpha

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

What effect does double strand damage have to DNA?

A
  • harder to repair than single damage
  • strands sometimes rejoin incorrectly and this can cause mutations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is dose rate?

A
  • the rate at which damage is caused, compared to the amount of radiation received
  • if the dose rate is lower, the cell can repair damaged DNA before more damage occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What factors affect tissue radiosensitivity?

A
  • the type of cells that make up the tissue
  • whether the cells are actively dividing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the radiosensitivity of stem cells.

A

Divide frequently therefore are very radiosensitive

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

Describe the radiosensitivity of differentiated cells.

A

No mitotic behaviour, therefore less radiosensitive

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

Which tissues would be considered highly radiosensitive?

A
  • bone marrow
  • lymphoid tissue
  • GI
  • gonads
  • embryonic tissues
17
Q

Which tissues would be considered moderately radiosensitive?

A
  • skin
  • vascular endothelium
  • lungs
  • lens of eye
18
Q

Which tissues would be considered least radiosensitive?

A
  • CNS
  • bone and cartilage
  • connective tissue
19
Q

What are the three responses of a cell to mutation?

A

Repaired = viable cell
Death = nonviable cell
Survives but remains mutated = cancer

20
Q

Define dose.

A

The measure of energy deposited in the subject by radiation, measured in Gy

21
Q

Define equivalent dose.

A

Absorbed dose multiplied by the weighting factor of the radiation, measured in Sv

22
Q

Define effective dose.

A

Equivalent dose multiplied by the tissue weighting factor, measured in Sv

23
Q

Which radiations have a weighting factor of 1?

A

X-rays, beta, gamma rays

24
Q

Which types of radiations have a weighting factor of 20?

A

Alpha

25
Q

What is the LNT?

A
  • linear no threshold
  • assumes all radiation is harmful, and there is no safety threshold
  • damage is directly proportional to radiation dose
26
Q

What are the two types of biological radiation effects?

A
  • deterministic
  • stochastic
27
Q

Describe deterministic effects.

A
  • tissue reactions
  • only occur over a certain threshold dose
  • severity is related to dose received
  • unusual in radiology (except interventional radiology)
  • effects seen a few days after exposure
28
Q

Describe stochastic effects.

A
  • no threshold
  • probability of occurrence is related to the dose received
  • effects are either somatic (in the recipient) or genetic (in the recipient’s children)
  • effects develop over years
29
Q

What are some deterministic effects seen in the body after radiation exposure?

A
  • hair loss
  • skin damage
  • sterilisation
  • bone marrow depletion
30
Q

How does radiation affect pregnancy?

A
  • embryo could be damaged or killed if exposed to enough radiation directly
  • during organogenesis, exposure can cause growth retardation
  • doses required are 1000s times greater than intraoral dentistry
31
Q

What are sources of background radiation?

A
  • cosmic rays
  • radionuclides in food
  • gamma radiation from soil, rocks etc
  • air travel
32
Q

What effective dose does an intraoral radiograph carry?

A

0.005mSv

33
Q

Define justification.

A

Practices must have sufficient benefit to individuals or society in order to offset the detriment

34
Q

Define optimisation.

A

Individual doses and the number of people exposed should be kept to as low as reasonably practicable (ALARP), taking into account economic and social factors

35
Q

Define dose limitation.

A

System of individual dose limits so that the risks to individuals are acceptable

36
Q

How are patient doses reduced?

A
  • E speed film or faster (require less photons)
  • kV range 60-70
  • focus to skin distance greater than 200mm
  • rectangular collimation
37
Q

What are DRLs?

A
  • diagnostic reference levels
  • standard doses for standard sized patients
  • adults = 0.9mGy for digital
  • child = 0.6mGy for digital
38
Q

Why is image quality important?

A

If the image quality is not sufficient then the x-ray is not justified

BDS3 RADIOLOGY (9 decks)

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