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Radiology > Radiation Biology-Day 2 > Flashcards

Radiation Biology-Day 2 Flashcards

1
Q

Radiobiology

A

The study of the effects of ionizing radiation on living systems.

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2
Q

2 possible results of radiobiology

A

Direct effect

Indirect effect

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3
Q

Direct effect

A

Energy passed directly through biologic molecule

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4
Q

Indirect effect

A

Energy absorbed by water in organism, and water is ionized.

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5
Q

Direct effects are __of biologic effects organisms

A

1/3

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6
Q

Direct effects: X-rays interact with biologic molecules by removing a ____ atom and an ____in the creation of free radicals

A

hydrogen; electron

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7
Q

Free radicals

A

Highly reactive

Short lived

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8
Q

Fate of free radicals

A

dissociations

cross-linking

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9
Q

Indirect effect: ___ of water producing organic free radicals

___ and ___ interact with organic molecules

__ of biologic damage comes from indirect effects

A

Radiolysis

Peroxide and peroxyl

2/3

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10
Q

How long do direct and indirect effects take to happen?

A

Both take 10^-5 seconds to happen. BUT years to manifest.

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11
Q

Interaction with DNA is the primary source of?

A

cell death, genetic mutations and carcinogenesis

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12
Q

DNA changes due to?

A

Breakages
Cross-linking to other DNA or proteins
Change or loss of base
Disruption of the hydrogen bonds between DNA strands

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13
Q

DNA Strand Breakage-describle single and double strand breaks

A

Single breaks are readily repairable using the second strand as a template

Double strand breaks are responsible for most cell killing, carcinogenesis and heritable effects

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14
Q

Most radiosensitive part of cell?

A

nucleus

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15
Q

Cell cycle sensitivity

A

Mitosis and G2 > G1 > S

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16
Q

___ and ___ aberrations (a departure from the normal)

A

Chromosome and chromatid

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17
Q

Frequency of mutations increase in proportion with

A

dose, no threshold

18
Q

Mutations usually

A

deleterious to organism

19
Q

Rate of mutations is reduced as time between

A

exposure and conception increases

20
Q

Law of Bergonie and Tribondeau

A

Radiosensitive cells are more:

Rapidly dividing
Longest mitotic potential
Undifferentiated cells

21
Q

Law of Bergonie and Tribondeau: High radiosensitivity

A

Bone marrow, spleen, lymph nodes, gonads, lymphocytes

22
Q

Law of Bergonie and Tribondeau: Medium radiosensitivity

A

Skin, organs (liver, heart, lungs)

23
Q

Law of Bergonie and Tribondeau: Low Radiosensitivity

A

Muscle, Bone, Nervous System

24
Q

DETERMINISTIC EFFECT

A

Effects that occur that depend on dose absorbed
Effects occur once threshold is reached
Caused by killing of many cells

25
Q

STOCHASTIC EFFECT

A

Effects occur independent of dose
NO THRESHOLD
Caused by sublethal damage to DNA

26
Q

Cancer treatment

A

Chemotherapy
Surgery
Radiation Therapy

27
Q

Diagnostic radiation

A

lower radiation levels for interpretation

28
Q

Therapeutic Radiation:

A

high radiation levels used to treat cancer

29
Q

Radiation Therapy aka

A

XRT

30
Q

Most common cancer affecting the oral cavity

A

Squamous cell carcinoma

31
Q

Prior to XRT what is prior choice of treatment?

A

local resection

32
Q

XRT consists of

A

60-70 Gy over 6-7 weeks

33
Q

Short term effects

A

Days to weeks after exposure

Effects are noted as a decrease in radiosensitive cells: hair, mucosa, bone marrow, lymphocytes

34
Q

Long term effects

A

Months to years post-exposure

loss of parenchymal cells and replacement of normal tissue with fibrous connective tissue

35
Q

Radiotherapy on Taste buds

A

Taste acuity reduced by a factor of 1000-10,000

Reversible; 60-120 days

36
Q

Radiotherapy on Salivary glands

A

Serous glands more sensitive
Saliva reduced and becomes more viscous
ph reduced

37
Q

Radiotherapy on teeth

A

Children show changes in tooth development

38
Q

Radiotherapy on radiation caries

A

Rampant form of dental decay
Lesions on buccal, occulsal, incisal, and palatal surfaces
Lesions circumferential around crown in cervical area

39
Q

Radiotherapy on Bone

A

Radiation damages vasculator and cortical bone
Destroys osteoblasts/osteoclasts
Leads to osteonecrosis of bone
Most important clinical feature

40
Q

Gy

A

Radiation dose

41
Q

As a dentist before radiation therapy

A

Restore all carious lesions

Remove teeth with extensive caries or poor periodontal support

Allow 2-3 weeks to heal

42
Q

As a dentist after radiation therapy

A

Daily application of viscous topical 1% neutral sodium fluoride gel in custom made applicator trays

Removal of teeth should be avoided

Radiology (8 decks)

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