Radiation Biology-Day 2

Question 1

Radiobiology

Answer 1

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

Question 2

2 possible results of radiobiology

Answer 2

Direct effect

Indirect effect

Question 3

Direct effect

Answer 3

Energy passed directly through biologic molecule

Question 4

Indirect effect

Answer 4

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

Question 5

Direct effects are __of biologic effects organisms

Answer 5

1/3

Question 6

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

Answer 6

hydrogen; electron

Question 7

Free radicals

Answer 7

Highly reactive

Short lived

Question 8

Fate of free radicals

Answer 8

dissociations

cross-linking

Question 9

Indirect effect: ___ of water producing organic free radicals

___ and ___ interact with organic molecules

__ of biologic damage comes from indirect effects

Answer 9

Radiolysis

Peroxide and peroxyl

2/3

Question 10

How long do direct and indirect effects take to happen?

Answer 10

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

Question 11

Interaction with DNA is the primary source of?

Answer 11

cell death, genetic mutations and carcinogenesis

Question 12

DNA changes due to?

Answer 12

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

Question 13

DNA Strand Breakage-describle single and double strand breaks

Answer 13

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

Question 14

Most radiosensitive part of cell?

Answer 14

nucleus

Question 15

Cell cycle sensitivity

Answer 15

Mitosis and G2 > G1 > S

Question 16

___ and ___ aberrations (a departure from the normal)

Answer 16

Chromosome and chromatid

Question 17

Frequency of mutations increase in proportion with

Answer 17

dose, no threshold

Question 18

Mutations usually

Answer 18

deleterious to organism

Question 19

Rate of mutations is reduced as time between

Answer 19

exposure and conception increases

Question 20

Law of Bergonie and Tribondeau

Answer 20

Radiosensitive cells are more:

Rapidly dividing
Longest mitotic potential
Undifferentiated cells

Question 21

Law of Bergonie and Tribondeau: High radiosensitivity

Answer 21

Bone marrow, spleen, lymph nodes, gonads, lymphocytes

Question 22

Law of Bergonie and Tribondeau: Medium radiosensitivity

Answer 22

Skin, organs (liver, heart, lungs)

Question 23

Law of Bergonie and Tribondeau: Low Radiosensitivity

Answer 23

Muscle, Bone, Nervous System

Question 24

DETERMINISTIC EFFECT

Answer 24

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

Question 25

STOCHASTIC EFFECT

Answer 25

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

Question 26

Cancer treatment

Answer 26

Chemotherapy Surgery Radiation Therapy

Question 27

Diagnostic radiation

Answer 27

lower radiation levels for interpretation

Question 28

Therapeutic Radiation:

Answer 28

high radiation levels used to treat cancer

Question 29

Radiation Therapy aka

Answer 29

XRT

Question 30

Most common cancer affecting the oral cavity

Answer 30

Squamous cell carcinoma

Question 31

Prior to XRT what is prior choice of treatment?

Answer 31

local resection

Question 32

XRT consists of

Answer 32

60-70 Gy over 6-7 weeks

Question 33

Short term effects

Answer 33

Days to weeks after exposure Effects are noted as a decrease in radiosensitive cells: hair, mucosa, bone marrow, lymphocytes

Question 34

Long term effects

Answer 34

Months to years post-exposure loss of parenchymal cells and replacement of normal tissue with fibrous connective tissue

Question 35

Radiotherapy on Taste buds

Answer 35

Taste acuity reduced by a factor of 1000-10,000 | Reversible; 60-120 days

Question 36

Radiotherapy on Salivary glands

Answer 36

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

Question 37

Radiotherapy on teeth

Answer 37

Children show changes in tooth development

Question 38

Radiotherapy on radiation caries

Answer 38

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

Question 39

Radiotherapy on Bone

Answer 39

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

Question 40

Gy

Answer 40

Radiation dose

Question 41

As a dentist before radiation therapy

Answer 41

Restore all carious lesions Remove teeth with extensive caries or poor periodontal support Allow 2-3 weeks to heal

Question 42

As a dentist after radiation therapy

Answer 42

Daily application of viscous topical 1% neutral sodium fluoride gel in custom made applicator trays Removal of teeth should be avoided