Brainscape's Knowledge GenomeTM

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


See full index

physics factoids > Radiation biology > Flashcards

Radiation biology Flashcards

1
Q

‘Exposure’

A

ability of X-rays to ionize air, measured in Roentgens

concentration of radiation, in air, at a specific point

ionization produced in a specific volume of air

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

Absorbed Radiation dose

Radiation dose

A

amount of energy absorbed per unit mass at a specific point (Gy or Rads)

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

Gy and Rads

A

1 Gy = 100 Rads

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

Equivalent dose =

A

Dose x weighting factor

weighting factor based on different types of radiation

For Xrays and gamma rays = 1

alpha particles = 20

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

Effective dose =

A

Type of radiation and type of tissue

Sv

EfD = EqD x Tissue factor

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

Kerma

A

PRIMARY energy transfer (no scatter, not overall dose)

Can’t measure in body, measure at air entrance point

Entrance air kerma

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

Kerman and photon energy

low vs high

A

Low energy photon primarily PE, KERMA and entry dose roughly the same

High energy photons pass through, KERMA = MORE than absorbed dose

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

KAP

A

Kerma x beam area

thought of as total radiation used in exam more than actual dose

INDEPENDENT of source distance

Mag will increase entrance skin kerma but NOT change KAP

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

Entrance Kerma, KAP and collimation

A

KAP WILL decrease with collimation

Entrance KERMA will increase a small amount 2/2 ABC

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

KERMA, KAP stochastic and deterministic risks

A

KAP estimate/correlates with stochastic risk

Entrance Air KERMA with deterministic effects

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

Relative Biologic Effectiveness

RBE calc?

A

Capability of radiation with differing LET’s to produce a biologic reaction

Dose of 250kV x-rays/ Dose in Gy of test radiation

ex: reaction produced by 5Gy of test radiation. It takes 10Gy of 250kV x-rays to produce same effect. RBE = ?

10/5 = 2. Test radiation is twice as good at producing the biologic effect

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

LET and RBE

as LET increases?

A

directly related to a point. Above a threshold (100keV/micrometer), max damage is being done and more radiation is ‘wasted’

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

Oxygen Enhancement Ratio

OER at high vs low LET

A

relative effectiveness of radiation to produce damage at different oxygen levels

Tissue is more sensitive to damage in an oxygenated state

Only relevant at LOW LET

HIGH LET will do a lot of damage in low or high oxygenated states (OER = 1. damage without oxygen = damage with oxygen)

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

Direct vs Indirect ionizing radiation

A

Direct act Directly on DNA

Indirect if they act on water (free radical fucks up DNA later)

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

Syndrome with most sensitivity to x-rays

A

Ataxia Telangiectasia

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

‘Instant death of a large number of cells’

A

1000 Gy in a period of seconds/minute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

‘Mitotic death’

A

When a cell dies after 1 or more divisions

(a small dose can do this)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

‘Mitotic delay’

A

A very small dose (0.01 Gy) just before a cell divides can cause a delay or failure in the timing of the normal dividing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Most sensitive phase

overall sensitivity of phases

A

M phase

M > G2 > G1 > S

(G1 = variable in length)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Law of B and T

cell sensitivity

A

Most sensitive cells = lots of turnover, not much differentiation (Skin, blood, GI tract, reproductive)

Less sensitive, little turnover, lots of differentiation (brain, nerves, muscles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Most sensitive part of GI tract?

A

small bowel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Survival curve graph

? vs ?

quasi-threshold

A

dose vs cell survival

repair mechanisms = quasi-threshold = shoulder on graph = sublethal damage to the cell

only exists with lower LET radiation curves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

effect on blood

A

lymphoctyes = most sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

ARS

3 subtypes

4 phases

A

4 phases

GI - latent - syndrome/subtype - recovery/death

Bone Marrow, GI, CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

ARS

Bone Marrow

Dose

latent period

outcome

A

>2Gy

1-6 weeks

possible to survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

ARS

GI

Dose

latent period

outcome

A

>8Gy

5-7 days

death within 2 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

ARS

CNS

Dose

latent period

outcome

A

20-50 Gy

4-6 hours

Death within 3 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

lethal dose 50/30

A

Dose that will kill 50% of people within 30 days

3-4 Gy without treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Fetus and radiation

First 2 weeks

A

50-100 mGy may cause fetal loss (all or nothing).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Fetus and radiation

8 - 15 weeks

A

8-15 weeks = MOST VULNERABLE

over 100-200 mGy a/w

reduced head diameter and retardation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Fetus and radiation

childhood leukemia

A

increased risk with just a few radiographs

32
Q

Fetal thyroid

A

BEFORE week 8 does NOT take up iodine

after that = hosed

33
Q

General risk of cancer

A

4-5% per Sv

34
Q

Skin stuff

Early transient erythema

Dose

onset

35
Q

Skin stuff

Robust erythema

Dose

onset

A

6 Gy

1 week

36
Q

Skin stuff

Telangiectasia

Dose

onset

A

10Gy

52 weeks

37
Q

Skin stuff

Dry desquamation

Dose

onset

A

13 Gy

4 weeks

38
Q

Skin stuff

Moist desquam/ulceration

Dose

onset

A

18Gy

4 weeks

39
Q

Skin stuff

Secondary ulceration

Dose

onset

A

24 Gy skin dose

>6 weeks

40
Q

Hair

temporary epilation

A

3Gy

21 days onset

41
Q

Hair

Permanent epilation

A

7 Gy

21 days

42
Q

Cataracts

anterior vs posterior

A

senile cataracts = anterior

radiation cataracts = posterior lens

43
Q

Cataracts latent period

A

20 years after exposure

44
Q

Cataracts acute exposure

45
Q

cataracts annual dose rate limit

A

0.15 Gy/year

46
Q

Sterility/infertility

female

A

In general younger patient, more dose required to cause sterility

female age 12 - 10 Gy

female age 45 - 2Gy

female no age given - around 6 Gy

47
Q

Sterility

male

A

Male temporary 0.15 Gy - 2.5 Gy

Male permanent - 5 Gy

48
Q

Male/Female shielding

A

Male

Just below symphysis

Female

1 inch medial to each palpable asis

49
Q

Symptom/Dose

nausea (30% of people)

A

0.75 - 1.25 Gy WB

50
Q

Symptom/Dose

Depress lymphocytes

A

0.25 Gy WB

51
Q

Symptom/Dose

LD 50/60 (Marrow)

52
Q

Symptom/Dose

LD 50/4 (GI)

A

8 - 10 Gy WB

53
Q

Symptom/Dose

LD CNS

54
Q

Symptom/Dose

double normal mutation rate

55
Q

Effective background USA dose

A

3mSv per year

56
Q

Dose trigger for addnl F/U

A

15 Gy to a single exposure field

sentinel event

57
Q

Exposure limits

Occupational

lens

A

150 mSv/year

58
Q

Exposure limits

Radiation worker

A

50 mSv/year

59
Q

Exposure limits

occupational

extremity

A

500mSv/year

60
Q

Public exposure limits

infrequent

61
Q

Public exposure limits

continuous

62
Q

Public exposure limits

embryo/fetus via mother

A

5mSv/year

(1mSv to fetus directly)

63
Q

Public exposure limits

fetus post declared preg

A

0.5mSv/month

64
Q

Public exposure limits

controlled areas

A

50 mSv/year

65
Q

Public exposure limits

uncontrolled areas

A

5 mSv/year

66
Q

Public exposure limits

Genetically Significant dose

67
Q

High yield blitz

majority of energy received by biologic material from x-rays is transferred by?

68
Q

High yield blitz

60% of damage to biologic tissue is mediated by?

A

free radicals

69
Q

High yield blitz

A

final number of DS DNA breaks more important than initial, some will be repaired

70
Q

High yield blitz

Risk of radiation induced Ca

adult

kid

old person

A

4-5% per Sv adult

15% per Sv kid

1/10th that older than 50

71
Q

High yield blitz

Transient erythema timing

A

can be seen in hours, main wave after 10 days

72
Q

High yield blitz

radiation sterility in females

A

mimics menopause

in males no effect on libido or hormone levels, latent period

73
Q

High yield blitz

A

Radon workers get more lung cancer

74
Q

High yield blitz

highest contributor to USA effective dose

A

inhaled Radon, an alpha emitter, 55% of effective dose

75
Q

High yield blitz

gen pop man made greatest exposure?

A

medical imaging

physics factoids (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions