Brainscape's Knowledge GenomeTM

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


See full index

Health Physics > Biological Effects of Radiation > Flashcards

Biological Effects of Radiation Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

What are two radiation effects on water?

A
  1. Primary Reactions (Direct Action)
  2. Secondary Reactions (Indirect Action)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The ______ reactions are responsible for much of the biological damage caused by _____ LET radiations.

A

The primary reactions are responsible for much of the biological damage caused by high LET radiations.

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

Define

What is a free radical?

A
  • A highly chemically reactive form of an element due to the presence of an unpaired valence electron.
  • It tries to combine chemically with other species so that its single unpaired electron can form a covalent bond with some other unpaired electron to complete its sub-shell.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Is a free radical an ion?

A

No

  • A free radical is electrically neutral.
  • It has an equal number of protons in the nucleus to balance the negative electrons.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What two free radicals are formed in irradiated water?

A
  1. Hydrogen radical (the hydrogen atom, not diatomic hydrogen)
  2. Hydroxyl radical (OH)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the overall time span that primary reactions take place?

A

10-10 seconds

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

What is the overall time span that secondary reactions take place?

A

10-5 seconds

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

What are the three most probable secondary reaction equations?

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

About ____ of the injuries produced by low LET radiation exposure to cellular DNA is traceable to the ______ radical.

A

About 2/3 of the injuries produced by low LET radiation exposure to cellular DNA is traceable to the hydroxyl radical.

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

Pharmaceuticals useful for treating radiation accident victims fall into what two types?

A
  1. Treatement for external radiation exposure
  2. Treatment for internally deposited radioactive material
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the three different uses of drugs to treat external radiation exposure?

A
  1. Pre-irradiation protection to reduce the amount of damage at the time of exposure.
  2. After-irradiation pharmaceutical to repair damage at the molecular level.
  3. Pharmaceuticals used to “jump-start” the body into producing new stem cells.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is cystene used for?

A
  • An organic compound that has been found to donate its hydrogens to neutralize hydroxyl free radicals.
  • It has been found to raise the LD50/60 in humans by a factor of up to 1.7 times.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you measure the usefullness of a protective agent?

A
  • Dose Reduction Factor (DRF)
  • DRF is the change to the normal lethal dose (LD50/30) for a test animal that can be produced.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define

LD50/30

A

The value of the dose delivered to a group of animals such that 50% of the exposed population will survive for 30 days without any medical treatment or intervention.

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

Define

LD50/60

A

The value of the dose delivered to a group of humans such that 50% of the exposed population will survive for 60 days without medical treatment or intervention.

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

What is the value for LD50/60?

A

410 rads +/- 150 rads

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

Describe

Cell cycle

A
  • G1 - Resting gap period
  • S - Synthesis phase (15 hours while cell duplicatse its DNA)
  • G2 - Resting gap period
  • M - Mitosis (1 hour)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define

Biodosimetry

A

The methods in which changes caused by exposure to ionizing radiation are directly measured in a living system to determine the radiation dose received.

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

Define

Checkpoint gene

A
  • Gene p53 acts as a gatekeeper during the first resting phase G1 of the cell cycle.
  • The cycle is put on hold by p53 if it detects DNA damage and only allowed to continue after repair has been completed.
  • If p53 is mutated, cancer risk increases.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Biodosimetry

What are the two different types of methods used in biodosimetry?

A
  1. Biological based techniques use detection of biological tissue damage (usualy at the cellular level).
  2. Physical measurements of changes induced by radiation in body tissues.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Biodosimetry

What is an advantage and disadvantage of physical measurement techniques?

A

Advantage

  • It can be performed at times well after the exposure incident.

Disadvantage

  • The downside is that it will be unknown whether the dose measured was received at a particular time or is the result of cumulative exposures over a lifetime.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Biodosimetry

What is an advantage and disadvantage of biological measurement techniques?

A

Advantage

  • Biological measurements are more sensitive and can detect lower radiation doses than physical measurements.

Disadvantage

  • Problems arise when it is realized that most of the biological damange is not completely radiation specific.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Biodosimetry

The two most commonly analyzed tissues in physical biodosimetry are ____ and ____.

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

The Law of Bergonie and Tribondeau concluded that cells tend to be radiosensitive if they have what three properties?

A
  1. Cells have a high division rate.
  2. Cells have a long dividing future.
  3. Cells are of an unspecialized types.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Define

Relative Biological Effectiveness

A

The ratio of biological effectiveness of one type of ionizing radation relative to another, given the same amount of absorbed energy.

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

Graph

RBE vs. LET

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

Graph

Curves for various dose-response theories.

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

What are the four major types of cells in circulating blood?

A
  1. Erythrocytes
  2. Lymphocytes
  3. Granulocytes
  4. Platelets
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the purpose of the human blood cell types?

A
  • Erythrocytes - Oxygen transport to the cells
  • Lymphocytes - Generate antibodies to fight infection
  • Granulocytes - Fight infection by phagocytosis
  • Platelets - Blood clotting agent and vessel integrity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Acute Radiation Exposure

In what exposure range does the GI tract become the leading organ of concern?

A

10 - 50 Sv

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

Acute Radiation Exposure

In what range does the Central Nervous System become the leading organ of concern?

A

Over 50 Sv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Acute Radiation Exposure

What is the “Therapeutic Range” for radiation exposure? What is the concern?

A

1 to 10 Sv

  • Maintenance of minimum levels of circulating blood cells.
  • Because blood cells originate from stem cells in the bone marrow, the effects seen in this range are often referred to as the “Bone Marrow Syndrome”
33
Q

Define

Late Effects

A
  • Effects which exhibit themselves a period of years after an acute exposure.
  • The incidence is generally dependent on the radiation dose, dose rate, age at the time of irradiation, and state of health.
34
Q

There are four main types of genetic mutations that occur in humans and animals

A
  1. Dominant mutations ⇒ Caused by a single gene from one of the parents to the offspring.
  2. Receissive mutations ⇒ Result only if the same altered gene is furnished by both parents.
  3. Chromosomal rearrangements ⇒ Lead to mutations by mixing up the order of the genetic code.
  4. Multifactorial mutation ⇒ The result of multiple genes being involved with the additional probability of influence from environmental factors (e.g., eating habits).
35
Q

Define

Doubling Dose

A

The radiation dose which, if delivered to a large population, would produce an additional number of mutations equal to the number of spontaneous (natural) mutations.

36
Q

What are examples of genetic mutations?

A
  • Anemia
  • Down syndrome
  • Asthma
  • Diabetes
37
Q

What is the BEIR VII (2006) estimated doubling dose?

A

82 +/- 29 rads

38
Q

What type of risk estimate is the doubling dose?

A

Relative risk of genetic injury (the risk is compared to the natural mutation rate).

39
Q

Define

Somatic Effects

A

The results produced directly in the exposed individual.

40
Q

What are thre categories of somatic effects?

A
  1. Life shortening (from accelerated aging)
  2. Leukemia
  3. Other cancers
41
Q

Define

Dose Rate Effectiveness Factor

A
  • Factor by which radiation cancer risks observed (following large acute doses) can be reduced when the same amount of radiation is delivered at low dose rates or in a series of small dose fractions.
  • Created as a method to recognize the existence of biological repair mechanisms.
  • The DREF could only be used for accumulated doses below 20 rem and dose rates less than 5 rem year-1.
42
Q

What is the value for DREF?

A

NCRP 64 (1980)

  • Between 2 and 10 for low LET radiations like X- and gamma rays.
  • It should only be used for accumulated doses below 20 rem and dose rates less than 5 rem year-1.

ICRP ⇒ 2

BEIR VII ⇒ 1.5

43
Q

Prenatal Radiation Exposure

What can radiation doses delivered during pregancy produce?

A
  • Spontaneous abortion
  • Malformed organs
  • Mental/growth retardation
  • Teratogenic effects
44
Q

Prenatal Radiation Exposure

When is prenatal death observed?

A

When radiation is received during the preimplantation phase (the first 2 weeks after conception).

45
Q

Prenatal Radiation Exposure

Production of deformed organs and limbs in the fetus is observed when?

A

During the organogenesis phase (2 to 6 weeks after conception)

46
Q

Prenatal Radiation Exposure

After 6 weeks post-conception, radiation exposure has what effect?

A
  • Stunted growth and possible mental retardation
  • The peak for mental retardation seems to be from 8 to 15 weeks after conception
47
Q

BEIR V (1990) concluded that doses up to _____ Sv, cancer mortality follows a _____ relationship, except for leukemia which follows a _____ relationship.

A

BEIR V (1990) concluded that doses up to 4 Sv, cancer mortality follows a linear relationship, except for leukemia which follows a linear-quadratic relationship.

Amount of effect seen = cD

Amount of effect seen = cD + kD2

48
Q

Describe

Mitotic cell death

A
  • Reproductive cell death / cellular inactivation.
  • Most common death from radiation.
  • Cells die because of damaged chromosomes while trying to divide.
49
Q

Describe

Apoptosis

A
  • Programmed cell death that occurs normally
  • Greek for “falling off”
50
Q

List

Types of radiation damage

A
  • Nonlethal damage
  • Sublethal damage
  • Potentially lethal damage
  • Lethal damage
51
Q

Decribe

Nonlethal radiation damage

A

Slows down, but does not stop, cell proliferation

52
Q

Describe

Lethal radiation damage

A

Damage is irreparable, irreversible, and leads irrevocably to cell death.

53
Q

Describe

Sublethal radiation damage

A

Cells be either be repaired, or accumulate more dose to become lethal.

This is the basis for fractionation in radiation therapy.

54
Q

Describe

Potentially lethal radiation damage

A

Cell death/survival can be modified by post exposure environmental conditions.

55
Q

List

Factors affecting sensitivity to radiation

A
  • Size of sensitive structure
  • Repair capacity
  • Genetic redundancy
  • Genome organization
  • Chemicals (radiosensitizers/radioprotectors)
  • Age and gender
  • Temperature
  • Dose rate
56
Q

Define

Oxygen Enhancement Ratio (OER)

A
  • OER is the ratio of the radiation dose given under anoxic conditions to produce a certain affect relative to a radiation dose given under full oxygenated conditions to produce the same effect.
  • Oxygen is the “most biological” factor that modifies the radiation response. Oxygen increases ⇒­ Radiosensitivity increases
  • Additional oxygen abundance creates additional free radicals which increase damage to target tissue.
57
Q

List

Four R’s of Radiobiology

A
  1. Repair
  2. Reassortment/redistribution
  3. Repopulation
  4. Reoxygenation
58
Q

Describe

Repair

(4 R’s of Radiobiology)

A
  • Prompt repair of sublethal damage
  • Fractionating the dose allows time for cellular repair prior to receiving the full dose
59
Q

Describe

Reassortment/redistribution

(4 R’s of Radiobiology)

A
  • Progression of cells through the cell cycle during the interval between radiation doses.
  • Cell cycle moves from G2/M (growth and mitosis are radiosensitive) to S (synthesis is radioresistant)
60
Q

Describe

Repopulation

(4 R’s of Radiobiology)

A
  • Increase of surviving fraction due to cell division
  • Time interval between cell cycle is greater than cell cycle division time, which causes an increase in the number of cells surviving.
61
Q

Describe

Reoxygenation

(4 R’s of Radiobiology)

A
  • Oxygen returns to hypoxic (oxygen depleted) cells increasing radiosensitivity.
  • Applies to tumor/cancer cells and is another reason fractionation aids radiation therapy.
62
Q

List

Required conditions for Acute Radiation Syndrome

A
  • Radiation dose must be large (> 0.7 Gy)
  • Dose typically must be external
  • Radiation must be penetrating (able to reach internal organs)
  • Dose delivered over a short time (typically minutes)
63
Q

List

Four stages of Acute Radiation Syndrome

A
  • Prodromal syndrome (0 – 48 hours)
  • Latent period (0 – 3 weeks)
  • Manifest illness (0 – 8 weeks)
  • Recovery or death (> 6 – 8 weeks)
64
Q

What are two direct effects of radiation on DNA?

A

Knocking-out tumor suppressor gene

  • TP53 gene ⇒ Tumor suppressor gene that is lost or mutated in more than half of all human tumors.
  • P53 protein ⇒ Produced by the gene controls arrest of cell cycle and pathway to apoptosis.

“Activating” oncogenes

  • Oncogene ⇒ Gene that contributes to cancer formation when mutated or inappropriately expressed.
  • “Activated” oncogenes ⇒ Allow bypass of apoptosis and enable proliferation of damaged/mutated cells.
65
Q

List

Indirect effects of radiation

A
  • Bystander effect ⇒ Effect extends to unirradiated cells, increasing the “target” cell population, or activing repair enzyme expression.
  • Genomic instability
  • Adaptive responses
  • Threshold and/or hormesis
66
Q

A woman is 10 weeks pregnant.

Give two reasons for and against taking a 2 rem X-ray on the woman’s abdomen.

A

Support

  • Radiation induced malformations to the fetus are not likely after 10 weeks of pregnancy.
  • Risks from cancer later in life are minimal for a dose of 2 rem in the abdominal area.

Against

  • Other diagnostic tests might provide the desired diagnostic information.
  • The desired diagnostic information will likely not aid in the medical treatment of the woman for her pregnancy.
67
Q

List 3 possible effects of in-utero exposure at 10 weeks of pregnancy

A
  1. Cancer in later life
  2. Mental retardation
  3. Congenital malformations
68
Q

Why does the oxygen enhancement ratio decrease with increasing LET?

A

Oxygen modifies indirect effects, but does not modify direct effects

Indirect effects come from gammas and X-rays with low LET; therefore, as LET increases, the necessity for the presence of oxygen decreases.

69
Q

What are the respiratory tract compartments?

A
  • Upper respiratory tract
  • Tracheal/bronchial tree
  • Lymphatic
70
Q

What are three pieces of information needed to determine the risk of injury to a fetus from a radiation exposure?

A
  1. Age of fetus
  2. Dose to fetus
  3. Dose to risk conversion factors for the effects possible at that stage in gestation
71
Q

Name three general types of biological effects of ionizing radiation that are taken into consideration in the derivation of dose limits for radiation workers

A
  • Stochastic ⇒ Somatic effects (e.g., cancer)
  • Non-stochastic ⇒ Deterministic effects (e.g., erythema)
  • Genetic ⇒ Hereditary effects in the progeny of the exposed individual
72
Q

List

Five deterministic effects resulting from exposure to acute, high dose rate ionizing radiation.

A
  1. Cataracts
  2. Epilation
  3. Skin erythema
  4. Desquamation (skin comes off in flakes)
  5. GI syndrome
73
Q

List three reasons for the increase to the risk coefficient in ICRP 60.

A
  • Revised dosimetry of Japanese bomb survivors (neutron dose now considered insignificant)
  • Change from an additive to a multiplicative risk projection model.
  • Observed increase in total cancers (other than leukemia) in the Japanese study is still rising (largely a result of the excess mortality of those exposed as children).
74
Q

What are the ICRP 60 risk coefficients for workers and the general public?

A

Worker ⇒ 0.04 Sv-1

General public ⇒ 0.05 Sv-1

75
Q

What is the difference between an additive and multiplicative risk projection model?

A

Additive ⇒ Postulates broadly that the excess mortality is independent of normal mortality.

Multiplicative ⇒ Postulates there is a simple proportion between the natural cancer mortality and excess due to radiation for the whole time after the minimum latency period.

76
Q

List three factors that contribute to the uncertainty of a specific risk factor calculation.

A
  • Age ⇒ How the risk varies as a function of time for persons exposed at various ages.
  • Dose ⇒ How the risk increases with dose.
  • Normal incidence ⇒ Statistical uncertainty associated with the relatively small number of radiation induced cases observed in a population in a given category compared to normal incidence.
77
Q

What will be the most likely effect from a 30 rem dose equivalent delivered to a fetus at 3 days, 3 weeks, and 3 months after conception?

A

3 days ⇒ Death

3 weeks ⇒ Teratogenic effects

3 months ⇒ Cancer

78
Q

Define

Genetic doubling dose

A

The dose of radiation that produces twice the frequency of genetic mutations as would have been observed without radiation.

79
Q

What is the range of the genetic doubling dose value?

What two studies were used to determine the genetic doubling dose?

A

50 – 250 rad

Megamouse and Fruit Fly experiments

Health Physics (17 decks)

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