Radiation Biology

Question 1

What do the free radicals from the indirect effects of radiation combine to produce?

Answer 1

Hydrogen peroxide

Question 2

What is a low energy incident photon?

Answer 2

Its energy is well below the binding energy of the electron.

Question 3

T/F Dental X-rays make up a high percentage of ionizing radiation sources.

Answer 3

false – it only makes up 0.26% of the artificial (non-background) radiation sources.

Question 4

Radiation is absorbed by water; molecules are ionized and form free radicals that damage biological molecules with the cell (including DNA)

Answer 4

Indirect effects of radiation

Question 5

Severity increases as the absorbed dose increases.

Answer 5

Deterministic effects

Question 6

Probability increases as the absorbed dose increases.

Answer 6

Stochastic effects

Question 7

What are the types of damages done to DNA?

Answer 7

• Change or loss of a base
• Breakage of a single or both DNA strand
• Cross-linking of DNA strands to other DNA strands or to proteins

Question 8

How do mutations affect cells and DNA?

Answer 8

• Altered cell functions
• Uncontrolled cell growth
• Heritable genetic effects (reproductive cells)

Question 9

What are the effects of radiation on the teeth of children?

Answer 9

• Delayed or aborted root development
• Dwarfed teeth
• Failure to form one or more teeth

Question 10

What are the types of naturally occurring background radiation?

Answer 10

• Radon
• Cosmic
• Internal radionuclides
• Terrestrial

Question 11

A flight from London to New York will equal to receiving a dosage of _________________ mSv which would be the same as getting a ______________________ dental x-ray

Answer 11

0.032 mSv, panoramic

Question 12

Which are the categories of biological effects of radiation?

Answer 12

• Deterministic: severity increases as the absorbed dose increases
• Stochastic: probability increases as the absorbed dose increases

Question 13

Radiation is absorbed by water; molecules are ionized and form _____ _________ that damage biological molecules within the cell (including DNA)

Answer 13

free radicals

Question 14

What is the biggest source of ionizing radiation that is naturally occurring?

Answer 14

radon

Question 15

What are “short term” effects?

Answer 15

first days or weeks after exposure

Question 16

What are “long term” effects?

Answer 16

months and years after exposure (damage to the fine vasculature)

Question 17

Which effect of x-rays has a bigger impact on biological macromolecules: direct or indirect?

Answer 17

indirect effect

Question 18

CT is an example of what type of radiation?

Answer 18

Artificial radiation

Question 19

True or False: All ionizing radiations can produce biological changes.

Answer 19

True

Question 20

What is the primary mechanism of indirect radiation damage?

Answer 20

Radiation ionizes water, forming free radicals that damage biological molecules.

Question 21

What is the Law of Bergonié and Tribondeau?

Answer 21

Radiosensitivity is directionally proportional to the mitotic rate of a cell and inversely proportional to the degree of differentiation

Question 22

Where are locations of deterministic effects of radiotherapy of the head and neck?

Answer 22

Oral mucosa, Taste buds, Salivary glands, Bone, Teeth, Musculature

Question 23

The further from the equator you are, the ___ you are exposed to cosmic radiation.

Answer 23

more

Question 24

What is a food that has one of the highest contents of radiation?

Answer 24

Brazilian nuts

Question 25

The stochastic effects are related to _____ doses of radiation

Answer 25

low

Question 26

The sum of equivalent doses weighted by radiosensitivity of exposed tissue or organ is called

Answer 26

effective dose

Question 27

What is cosmic radiation?

Answer 27

Cosmic radiation comes from the stars and the amount of exposure varies with altitude.

Question 28

What cells are intermediately radiosensitive?

Answer 28

The intermediately radiosensitive cells are the fine vasculature, growing bone and cartilage, salivary glands, thyroid glands, lungs, kidney, and liver.

Question 29

T/F: In coherent scattering, there is a significant biological effect.

Answer 29

False. There is NO biological effect because there is no ionization.

Question 30

What is the basis of stochastic effects of radiation?

Answer 30

the probability increases as the absorbed dose increases

Question 31

What are the two sources of radiation?

Answer 31

* Naturally occurring (background radiation) * Artificial

Question 32

What are some sources of artificial radiation?

Answer 32

CT, radiology, dental, consumer products

Question 33

How does age have to do with radiosensitivity/ being a modifying factor?

Answer 33

Younger patients are at higher risks, as they have more radiosensitive cells and more time to develop radiation-induced cancer.

Question 34

What happens when both strands of DNA are damaged in a cell?

Answer 34

A DNA double-strand break is the most important damage type and is believed to be the detrimental event for cell killing, tumor-induction, and heritable effects of ionizing radiation.

Question 35

What organs, cells etc. have a HIGH radiosensitivity?

Answer 35

* Lymphoid Organs * Bone Marrow * Testicles (Germ Cells) * Intestines * Mucous Membranes

Question 36

How is the double-stranded helix held together?

Answer 36

weak hydrogen bonds between nucleotide base pairs

Question 37

Deterministic effects on musculature:

Answer 37

* inflammation * fibrosis * contracture and trismus * masseter and pterygoid

Question 38

Which part of the salivary glands is radiosensitive & what can damage of this structure lead to?

Answer 38

The parenchymal component & atrophy of glandular tissue.

Question 39

What are the ways ionizing radiation damages biological tissues?

Answer 39

Through direct and indirect effects. Direct hits critical cellular components like DNA, indirect ionizes water molecules forming free radicals.

Question 40

What is osteoradionecrosis?

Answer 40

Bone tissue death due to radiation-induced damage to the bone's vascular supply.

Question 41

What causes radiation caries?

Answer 41

changes in salivary glands and saliva production

Question 42

What is mucositis?

Answer 42

area of oral mucosa with redness and inflammation

Question 43

How is a breakage of a single strand of DNA repaired?

Answer 43

Enzymes + intact second strand as a template

Question 44

A double stranded helix held together by weak hydrogen bonds between nucleotide base pairs. It contains genetic information responsible for the development and function of an organism

Answer 44

Deoxyribonucleic acid (DNA)

Question 45

Breakage of a single DNA strand typically has ___ biologic consequence

Answer 45

little

Question 46

What is an analogy for how the Stochastic effect works?

Answer 46

It's like the lottery. Buying more tickets will increase your chances of winning, but it will have no effect on the amount you win. Cancer is a Stochastic effect. You cannot control the severity of it but the probability of getting it will be affected.

Question 47

What is osteoradionecrosis?

Answer 47

It is when bone is exposed to radiation and becomes necrotic. You lose osteoblast activity; there is reduced vascularization, and osteoclast activity is less regulated. Bone then becomes more prone to infection

Question 48

How does Compton Scattering differ from Photoelectric Absorption?

Answer 48

**Photoelectric Absorption:** Photon disappears, full energy transfer **Compton Scattering:** Photon changes direction, partial energy transfer Both cause ionization