Radiation Biology

Question 1

Somatic Cells

Answer 1

Cells in the human body - i.e. skin, muscle,)

Question 2

chromosomes

Answer 2

clusters of DNA molecules

Question 3

DNA

Answer 3

Central nucleus of a human cell holds the genetic code
large macromolecule = DNA
Hereditary information
Double helix
Base pairs = adenine, guanine, thymine, cytosine

Question 4

genetic cells

Answer 4

Cells of reproductive organs
females = oogonium
males = spermatogonium
Under go meiosis

Question 5

germ cells

Answer 5

immature cell

contain all hereditary information for an individual

Question 6

LET

Answer 6

how the ionizing radiation energy is deposited along a track or path in tissue.

High LET = passes thru tissue depositing large amount of energy in a short distance (greater biologic effect) = Alpha & Beta particles

Low LET = spreads energy over a large distance (does not cause significant damage in any one cell) - x-ray & gamma rays

Question 7

meiosis

Answer 7

reduction and division of genetic cells

Number of chromosomes is reduced to half 46 to 23

Question 8

mitosis

Answer 8

Division of somatic cells
Phases:
1- Prophase
2- Metaphase
3- Anaphase
4- Telophase

Question 9

RNA

Answer 9

Contained in both cell nucleus and cytoplasm
Similar to DNA but with a single strand of nucleic acid
Messenger RNA
Transfer RNA

Question 10

cataracts

Answer 10

cloudiness or opacity of eye
single acute dose of 2 Gy
threshold dose of 10 Gy
latent period = several years

Question 11

epilation

Answer 11

temporary hair loss

threshold above 3 Gy

Question 12

erythema

Answer 12

redness of skin

dose level of 6 Gy (600 rad)

Question 13

gastrointestinal syndrome

Answer 13

6 - 10 Gy
kills most stem cells in the Gi tract
All hematologic effects and…
severe nausea, vomiting and diarrhea

Death in 2 weeks

Question 14

GSD

Answer 14

measures effect on the genetic pool of radiation exposure to the gonads

Medical exposures contribute to about 200 uGy (20 mad)

Question 15

hematologic syndrome

Answer 15

affects blood forming tissues
depression of bone marrow

decrease in WBC, RBC, thrombocytes and lymphocytes

death in 3 weeks
3 Gy

Question 16

latent period

Answer 16

2nd stage of high dose effects
no clinical or visible symptoms

few hours to several days

Question 17

manifest stage

Answer 17

3rd stage - three syndrome become manifest, hematologic, GI and CNS

Question 18

OER

Answer 18

oxygen enhancement ratio of the radiation doses necessary to produce the same effect w/ and w/o oxygen

high LET value of 1 = so effective in producing damage that the presence or absence of oxygen does NOT matter

low LET value of 2 to 3 = oxygen enhances the effect of radiation

Question 19

prodromal stage

Answer 19

Initial stage of radiation response
less than 1Gy may show symptoms
varying degrees of nausea, vomiting and diarrhea

Question 20

RBE

Answer 20

biological effect of radiation with different LET value are compared by comparing their RBE

Ratio of dose standard to produce the same biological effect

X-rays have an RBE close to 1

High LET have have higher RBE