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radiation biology > Radiation Biology > Flashcards

Radiation Biology Flashcards

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AP® Biology flashcards
1
Q

What does a cell survival curve describe?

A

The relationship between dose and the proportion of cells that survive

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2
Q

2 definition of cell death?

A

Loss of function (differentiated cells) & Loss of reproductive integrity (proliferating cells)

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3
Q

What is Cell survival?

A

A Cell community that kept its reproductive integrity (not only capability)

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4
Q

What is Clonogenic capability?

A

A cell survivor that reproduces indefinitely to produce a large clone or colony.

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5
Q

What is the Law of Bergonie & Tribondeau?

A

The law is that cell radiosensitivity is related to: Cell mitotic rate; Cells that undergo many future mitosis; and Cell that is the most primitive in differentiation.

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6
Q

Which cells are the exception to the law of Bergonie & Tribondeau?

A

Oocytes & Lymphocytes

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7
Q

What are the major ‘Direct” effects of radiation on tissue cells?

A

Hypoplasia & Atrophy (inhibition of mitosis, precocious maturation, mitotic linked death)

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8
Q

Salivary glands are affected how, and by what radiation dose?

A

At 20-30 Gy they recover in 6-12 months with reduced salivary flow.
At 60 Gy we see complete destruction of the gland,

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9
Q

What is the definition of ‘Doubling dose’?

A

The amount of radiation a population requires to produce, in the next generation, as many additional mutations as arise spontaneously.

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10
Q

What is the Nyquist Theory?

A

The best resolution is half (0.5) the sampling frequency.

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11
Q

3 types of radiation damage?

A

Lethal, Potentially lethal damage (PLD), and Sublethal damage.

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12
Q

What are the 4 R’s of radiobiology?

A

Repair, Reassortment, Repopulation, Reoxygenation

Repair, Reoxygenation, Redistribution, Repopulation

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13
Q

What are 5 most radiosensitive tissues?

A

Lymphoid, Hematopoietic, Spermatogenic, Ovarian follicular epithelium, intestinal epithelium.

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14
Q

What are 4 medium radiosensitive tissues?

A

Connective tissue, Fine vasculature, Growing cartilage & bone, Conn. tissue of the CNS.

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15
Q

What are 5 radioresistant tissues?

A

Mature cartilage & bone, Epithelium of many tissues, neuronal tissue, muscle (striated)

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16
Q

What are the 4 stages of Acute radiation syndrome?

A

Prodromal, Latent, Manifest illness, Recovery or death.

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17
Q

What are the signs of Prodromal (NVD) stage?

A

Nausea, vomiting, diarrhea. (Deterministic effect)

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18
Q

What is the Latent stage?

A

When the patient looks and feels generally healthy.

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19
Q

What is the Manifest illness stage?

A

When the patient has symptoms, and can last from hours to months.

20
Q

What is Cerebrovascular syndrome? At what dose?’Early Lethal Effects’?

A

Happens at >50 Gy. Severe NVD, disorientation, respiratory distress, and death occurs within hours

21
Q

What are signs and dose for Gastrointestinal syndrome?

A

> 10 Gy. Death within 3-10 days. Symptoms due to depopulation of epithelial lining of GI tract. Severe NVD.

22
Q

What are signs and dose of Hematopoietic syndrome?

A

<8Gy. Death within 30-60 days post radiation. Suppresses normal bone marrow and spleen functions.

23
Q

Compare the pathophysiology of GI syndrome & hematopoietic syndrome.

A

The difference is the turnover time of the cells in the respective tissues. GI cells turnover much faster, so this syndrome will kill you faster .

24
Q

In Humans what is LD 50/30 and LD50/60 doses?

A

LD 50/30 is defined as the dose which causes a mortality rate of 50% of a group within a specified time.
LD 50/30 occurs at ~6 Gy.
LD 50/60 occurs at ~ 4 Gy.

25
Q

What is the major tumor suppressor gene?

A

P53

26
Q

What is ‘Adaptive Response’?

A

This is when large radiation exposure is preceded by by a small “tickle” dose, the effect of the large dose can be diminished. (like getting a tan to prevent sunburn)

27
Q

What are the most Radioresistant phases of the cell cycle?

A

S & G2.

28
Q

What are the most Radiosensitive phases of the cell cycle?

A

M (and late G2???)

29
Q

What are the advantages to preoperative XRT?

A

Unresectable lesions may become resectable; Extent of surgical resection diminished; smaller treatment portals; decreased metastasis. Disadvantage is decreased wound healing.

30
Q

What are advanatages of post-operative XRT?

A

Better surgical staging; greater dose can be given; tissue heals better; surgical resection is easier. Disadvantage is distant metastasis by manipulation.

31
Q

What is the acute toxicity limiting factor for an aggressive XRT schedule?

A

Mucositis

32
Q

What is the dose required for permanent sterility in men and women?

A

Men - 6 Gy single dose

Women - 2 Gy single dose

33
Q

What is the monthly radiation limit for pregnant women?

A

0.5 mSv per month

34
Q

What is the difference between natural cataracts & radiation induced cataracts?

A

Natural cataracts start on the external aspect of the lens, while radiation induced cataracts start on the internal aspect (at the posterior pole).

35
Q

What is the threshold dose for cataracts?

A

2 Gy, or 8 Gy if fractionated. (also the latent period becomes shorter if dose is increased)(This shows its a deterministic “late” effect).

36
Q

What is ‘Inverse dose Rate’?

A

This is when decreasing the dose rate actually increases cell killing. Due to allowing cells to cycle through the cell cycle, instead of stopping at G2.

37
Q

Definition of Absorbed Dose.

A

Measure of energy absorbed by any type of radiation per unit mass of any type of matter. Unit - Gy.

38
Q

Definition of Equivalent Dose.

A

Used to compare biologic effects of different types of radiation. Uses Radiation factor. Unit - Seivert.

39
Q

What is formula for Equivalent dose?

A

HT = ∑ WR x DT

40
Q

Definition of Effective Dose?

A

The sum of all of the weighted equivalent doses in all the tissues or organs. Uses a Tissue weighting factor.

41
Q

What is the ‘Negligible Individual dose’?

A

Dose below which further efforts to reduce radiation exposure to the person are unwarranted. 0.01 mSv.

42
Q

What are the dose limits for Occupational exposure?

A

50 mSv/year, or 10 mSv x Age.

43
Q

What is the effective dose limit for a pregnant woman?

A

0.5 mSv/month

44
Q

What is effective dose limit for the public?

A

Frequent exposures - 1 mSv/year. Infrequent exposures - 5 mSv/year.

45
Q

What is Dose limit for Deterministic effects for the Lens of the Eye?

A

150 mSv/year.

46
Q

What is the does limit for deterministic effects for the skin, hands, and feet?

A

500 mSv/year.

radiation biology (1 decks)

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