Biological Effects of Ionizing Radiation (V. 2)

Question 1

two types of biological effects on a tissue level

Answer 1

• somatic effects

- genetic effects

Question 2

somatic effects includes all irradiated body cells except _____

Answer 2

germ cells of reproductive system

Question 3

somatic effects are __ and may be….

Answer 3

deleterious; may be stochastic or deterministic

Question 4

genetic effects include…

Answer 4

responses of irradiated reproductive cells

Question 5

genetics effects become primarily important when they are passed on to ______; genetic effects have no consequence on those who….

Answer 5

future generations; do not procreate

Question 6

somatic effects can be…

Answer 6

• acute

- delayed/chronic (latent)

Question 7

acute somatic effects time and instance

Answer 7

within 60 days, usually after a single massive dose

Question 8

delayed somatic effects time

Answer 8

two months (60 days) to as late as 20 years

Question 9

time lapse between radiation exposure and appearance of effects

Answer 9

latent period (usually only used in related to stochastic (malignancy) results)

Question 10

magnitude of somatic effects depends on…

Answer 10

• individual
• species
• cellular/tissue
• extent of exposure (full v. partial body)
• total dose
• dose rate

Question 11

individual variability refers to that certain individuals in the same species are more _____ than others in response to radiation

Answer 11

sensitive or resistant

Question 12

the expression ______ is frequently used in radiobiology

Answer 12

LD50 (30 days)

Question 13

LD50 means that a certain dose ___________, and the 50% who survive are due to _____

Answer 13

kills 50% of exposed animals within 30 days, individual variability

Question 14

species variability notes…

Answer 14

mammals take less Gy than yeast, fruit fly, bacteria…

Question 15

LD50 refers to…

Answer 15

total body exposure

Question 16

dose rate dependence…radiation dose that would be lethal if given in a short time may result in _______ if given in small increments during a period of years

Answer 16

no detectable effects

Question 17

around ___ of somatic damage is repaired, but irreparable damage is ______

Answer 17

4/5, cumulative

Question 18

when cumulative somatic damage reaches high level, ______ may appear

Answer 18

clinical manifestations

Question 19

3 dose-effect relationship theories

Answer 19

• threshold response
• linear quadratic response
• linear reponse

Question 20

threshold dose theory

Answer 20

an increase in radiation dose may not produce an observable effect until tissue has received a minimal level of exposure

Question 21

in threshold dose theory, once the threshold has been exceeded, increasing the dose will demonstrate exceeding _____

Answer 21

tissue damage

Question 22

examples of threshold dose responses

Answer 22

cataract, erythema of skin

Question 23

linear response theory

Answer 23

suggests all exposure carries a certain probability of harm and that effects of multiple small doses are additive
“no safe dose”
every dose carries risk

Question 24

linear quadratic response theory

Answer 24

implies lesser risk at lower dose rate than linear response or when exposure is fractionated
however, no safe dose

Question 25

____ are more radioresistant probably due to high levels of ____

Answer 25

females, estrogen

Question 26

lower metabolic rate and lower stage of nutrition, the ______

Answer 26

higher the radioresistance

Question 27

_________ are more efficient in causing biological damage

Answer 27

alpha particles

Question 28

radioresistance of many biological tissues increases ___ times when irradiation is conducted with reduced oxygen

Answer 28

2-3

Question 29

dose required to produce deterministic effects

Answer 29

1-2 Gy

Question 30

with chronic deterministic effects, there is usually a __________

Answer 30

threshold dose below which the effects are not manifested

Question 31

with chronic deterministic effects, with increasing dose the severity of defect ____

Answer 31

increases

Question 32

skin deterministic effects

Answer 32

1.65-3.5 Gy = erythema | higher doses = dermatitis

Question 33

hair determinstic effects

Answer 33

2. 0-6.0 Gy = epilation (loss of hair) | - ^^latent period of 3 weeks

Question 34

sterility deterministic effects (exposure to gonads)

Answer 34

``` males = 4.0 Gy females = 6.5 Gy ```

Question 35

when was x-ray discovered?

Answer 35

November 1895

Question 36

first case of radiation-induced human injury

Answer 36

1896

Question 37

first case of x-ray induced cancer reported

Answer 37

1902

Question 38

cataract deterministic effect

Answer 38

2. 0-5.0 Gy for single exposure | 10. 0 Gy for exposures over a period of month/years

Question 39

standard therapeutic radiation dose for treating cancer = _____ administered over a period of ______ at a rate of ____ Gy ____

Answer 39

50-60 Gy, 10-14 weeks at a rate of 2.5 Gy twice weekly

Question 40

adult teeth are ______ to direct effects of radiation; no effect on _______

Answer 40

very resistant, enamel/dentin/cementum

Question 41

radiation effect/caries type in which individuals whose salivary glands do not function d/t radiation (xerostomia)

Answer 41

radiation caries

Question 42

radiation caries occur at the ____

Answer 42

CEJ

Question 43

radiation on developing teeth characteristics....

Answer 43

less than 10 Gy has very little/no visible effect

Question 44

radiation to infant and their developing dentition may include...

Answer 44

- destruction of tooth bud - tooth malformation - delay in eruption

Question 45

small teeth/small roots in response to radiation can be termed...

Answer 45

radiation stunting of teeth

Question 46

most serious complication of radiation effects on oral tissue

Answer 46

jaw osteoradionecrosis

Question 47

jaw osteoradionecrosis is primarily due to damage to the _____ of the jaw and the consequent __________

Answer 47

blood vessels, decreased capacity of the bone to resist infection

Question 48

jaw osteoradionecrosis is more common in ____

Answer 48

Mandible than the Mx

Question 49

with jaw osteoradionecrosis, ________ makes possibility of bone infection/necrosis becomes very high

Answer 49

tooth extraction/other injury

Question 50

at 3rd or 4th week of radiation therapy, oral mucosa becomes ______(___). As therapy continues, mucosa forms ______.

Answer 50

red and inflamed (mucositis), yellow pseudomembrane

Question 51

when is mucositis d/t radiation therapy most severe?

Answer 51

at end of treatment period

Question 52

with mucositis d/t radiation therapy, secondary infections by _____ is a common complication

Answer 52

candida albicans

Question 53

with mucositis d/t radiation therapy, healing begins soon after ____ and is usually complete in about _____ after therapy

Answer 53

treatment, two months

Question 54

taste acuity is _________ into radiation therapy; complete recovery of taste usually occurs in ________ following treatment completion

Answer 54

reduced or lost about 4 weeks; 2 to 4 months