Radiation Biology

Question 1

This occurs when an X-ray photon ionizes water which results in the production of hydrogen and hydroxyl free radicals

Answer 1

Free radical formation

Question 2

Uncharted atom or molecule that exists with a single , unpaired electron in its outermost shell ( highly reactive and unstable)

Answer 2

Free radical

Question 3

To achieve stability , the free radicals may :

Answer 3

> recombine with other free radicals without causing changes in the molecule
combine with other free radicals and cause changes
combine with ordinary molecules to form a toxin (hydrogen peroxide) capable of producing widespread cellular changes

Question 4

2 theories of radiation injury

Answer 4

Draft theory and indirect theory

Question 5

Theory where cell damage results when ionizing radiation directly hits critical areas, or targets within the cell

Answer 5

Direct theory

Question 6

Theory where X-ray photon are absorbed within the cell and cause formation of toxins which in turn damage the cell

Answer 6

Indirect theory

Question 7

2 classification of biological effects of radiation

Answer 7

Stochastic and deterministic effects

Question 8

The probability of occurrence increases with the increasing absorbed dose ( cancer and genetic mutation)

Answer 8

Stochastic effects

Question 9

The severity of the response is proportional to the dose (loss of hair, cataract formation, acute radiation syndrome)

Answer 9

Deterministic effects

Question 10

2 radiation effects

Answer 10

Somatic and genetic effects

Question 11

Effects that are seen within minutes, days or weeks after exposure (acute radiation syndrome)

Answer 11

Short term effects

Question 12

Effects that appear after years, decades or generations (cancers, birth abnormalities)

Answer 12

Long term effects

Question 13

Effects on radiation seen on the person irradiated (cancer, cataracts)

Answer 13

Somatic effect

Question 14

Effects not seen on the person irradiated but are passed on to future generations (genetic mutations)

Answer 14

Genetic effects

Question 15

TRUE or FALSE

Nucleus is more radio sensitive than cytoplasm

Answer 15

True (sensitive site is the DNA within the chromosomes)

Question 16

TRUE or FALSE

The type of damage depends on the stage of cell in the cell cycle at time of irradiation

Answer 16

True

Question 17

TRUE or FALSE

Younger the tissue and organ, the more radio resistant

Answer 17

False (radio sensitive )

Question 18

TRUE or FALSE

When level of metabolic activity increases, the radiosensitivity decreases

Answer 18

False ( also increases)

Question 19

TRUE or FALSE

As the rate for cells and the growth rate for tissue increases, the radiosensitivity increases

Answer 19

True

Question 20

TRUE or FALSE

Mature cell is more resistant to radiation

Answer 20

True

Question 21

Radiation effects on cell kinetics

Answer 21

Mitosis delay, cell death and recovery

Question 22

Characteristics of most radiosensitive cells

Answer 22

> have high mitotic rate
undergo many future mitoses
most primitive in differentiation

Question 23

5 categories of radiosensitivity

Answer 23

> vegetative inter mitotic cells - basal cells
differentiating intermitotic cells - spermatocytes
multi potential CT cells - fibroblast
reverting postmitotic cells- parenchymal cells of the liver
fixed postmitotic cells- neurons

Question 24

Severity of damage depends on the amount of radiation received

Answer 24

Dose

Question 25

Rate of exposure

Answer 25

Dose rate

Question 26

Rate of loss of energy from a particle as it moves along its track

Answer 26

Linear energy transfer (LET)

Question 27

TRUE or FALSE

Greater cell damage occurs in the presence of oxygen

Answer 27

True

Question 28

2 system used to define radiation measurement

Answer 28

> traditional system ( R, rem, rad)

> systeme Internationale unit (Kerma, sv, gy)

Question 29

Measurement of ionization in air produced by X-rays

Answer 29

Exposure

Question 30

Quantity of x- radiation or gamma radiation that produces and electrical charge of 2.58 x 10-4 coulombs in a kilogram of air at standard temperature and pressure conditions

Answer 30

Roentgen

Question 31

Unit that Measures the kinetic energy from photons to electrons

Answer 31

Kerma

Question 32

What are the HIGH radiosensitive organs

Answer 32

Lymphoid organ, testis, intestine, mucous membrane, bone marrow

Question 33

What are the intermediate radiosensitive organs

Answer 33

Growing cartilage and bones, fine vasculature, liver, lungs, kidney and salivary glands

Question 34

What are the low radiosensitive organs

Answer 34

Optic lens, mature erythrocytes, muscle cells, neurons

Question 35

Amount of energy absorbed by a tissue

Answer 35

Dose

Question 36

This is used to compare the biological effects of 2 different types of radiation to a tissue or organ

Answer 36

Dose equivalent measurement

Question 37

A special unit of dose that is equal to the deposition of 100 ergs if energy per gram of tissues (100 ergs/gm)

Answer 37

Radiation absorbed dose

Question 38

Sum of the products of absorbed dose average over a tissue or organ and a quality factor (QF) or radiation weighting factor (WR) specific for a type of radiation

Answer 38

Rem

Question 39

Dimensionless multiplier used to place the exposure effects of different types of radiation on a common scale

Answer 39

Quality factor

Question 40

This is used to estimate the risk in humans (WT xHT “equivalent dose to each organ or tissue)

Answer 40

Effective dose

Question 41

Critical organs during dental radiograph exposure

Answer 41

Skin, thyroid glands, eyes, bone marrow

Question 42

Study of the effects of ionizing radiation on living systems

Answer 42

Radiation biology