Ch. 11 Radiobiology & Radiation Safety

Question 1

biologic damage produced from received exposure based on radiation type
- Pts receive both an exposure & absorbed dose (absorbed dose will always be greater than exposure)
-absorbed dose & dose equivalent are always identical numbers

Answer 1

Radiation Weighing Factor

Question 2

-Ionization may occur to any part of the cell including the material that makes up the membrane, the water within the membrane, or the DNA forming free radicals
-some damage may cause malfunction to the cell

Answer 2

Biological effects of radiation: cellular level

Question 3

the amount of xray energy transferred on average per the length of passage through the tissue (explains how much radiation was absorbed in a given section)
- high transfers of a large amount into a small section can do more damage)

Answer 3

Linear Energy Transfer (LET)

Question 4

when tissues contain more oxygen, they are more sensitive

Answer 4

Oxygen Enhancement Ratio (OER)

Question 5

Age (younger is more sensitive)
Differentiation (Simple cells are more sensitive)
Metabolic rate (cells that use energy more rapidly are more sensitive)
mitotic rate (cells that multiply fast are more sensitive)

Answer 5

Cell sensitivity based on the Law of Bergonie & Tribondeau

Question 6

Blood cells, Thyroid gland, breast tissue, cells with mucous

Answer 6

cell types that are extremely sensitive

Question 7

nerve, muscle, bone cells

Answer 7

cell types that are not sensitive

Question 8

tissues of embryos, fetuses, infants, children, adolescents

Answer 8

tissue types that are very sensitive

Question 9

when do destructive interaction occur?

Answer 9

at atomic level

Question 10

effects observed within 3 months of exposure
- very predictable
- quantity of exposure is required to produce the effects

Answer 10

short-term effects

Question 11

hematologic system (blood)
gastrointestinal system (digestive tract)
central nervous system (brain & spinal cord)
- compromised immune system caused by death of white blood cells
- unable to fight off infections
- fatal, but suffering is prolonged

Answer 11

acute radiation syndrome (ARS)

Question 12

“latent effects” observed several years after exposure & may not be apparent until 30 years
- 10-15 years is when the greatest % of effects are observed
- very random & unpredictable

Answer 12

Long-term effects

Question 13

cataracts
increased risk of carcinogenesis (cancer)
shortened life span
leukemia (blood/bone marrow cancer)

Answer 13

typical long-term effects

Question 14

effects the body & tissues of the irradiated individual

Answer 14

Somatic

Question 15

occur as a result of damage to the reproductive cells of an irradiated person
-defects are seen in children/grandchildren
-mutations/changes to reproductive cells after gonads have been exposed

Answer 15

Genetic

Question 16

“as low as reasonable achievable”
- reduce radiation by avoiding repeat exposures, use small radiation fields, use the highest kvp. maintain 40” SID, Shield whenever possible

Answer 16

ALARA

Question 17

fluoroscpy & mobile radiopgraphy

Answer 17

greatest occupational risk

Question 18

Time, Distance, Shielding

Answer 18

3 principle methods of personnel protection

Question 19

dosimeters use aluminum oxide as a radiation detector & is processed using laser light
-measures small doses more accurately with long term stability

Answer 19

Optically Stimulated Luminescence (OSL) Dosimeter

Question 20

worn at collar level outside of lead apron
- a second dosimeter worn at waist level under lead apron if pregenat

Answer 20

where are dosimeters worn?

Question 21

a system used to calculate the upper limit of occupational exposure
-applies to individuals over 18 & are non pregnant
-assumed to be whole-body dose

Answer 21

Effective Dose Limit

Question 22

lifetime effective dose in mSv should not exceed 10x the person’s age
(Ex: 30 y/o = 300 mSv)

Answer 22

Cumulative Effective Dose (CumEfD)

Question 23

monthly limit to the embryo/fetus for a pregnant worker

Answer 23

0.5mSv

Question 24

annual effective dose limit

Answer 24

50 mSv

Question 25

effective dose limit for lens of the eye

Answer 25

150 mSv

Question 26

what is the dose equivalent biologic effect of each of the following:
- blood
-Radiation Sickness (nausea, diarrhea)
-Radiation burn (erythema “skin redness)
-genetic effects (temporary sterility of gonads)
-50% chance of death (LD50/30)
-death

Answer 26

-250 mSv
-1500 mSv
-2000 mSv
-2500 mSv
-3000mSv
-6000 mSv

Question 27

What is the SI unit and the Standard unit for Air KERMA (Exposre)

Answer 27

SI unit:
-Gray or Coulomb/kilogram

Standard Unit:
-Roentgen

Question 28

what is the SI unit and the Standard unit for Absorbed Dose

Answer 28

SI unit:
- Gray

Standard Unit:
-Rad

Question 29

What is the SI unit and Standard unit for Occupational Dose (Dose Equivalent)

Answer 29

SI unit:
- Sievert

Standard unit:
-Rem

Question 30

what is the SI unit and the Standard unit for Radioactivity

Answer 30

SI Unit
- Becquerel

Standard unit:
-Curie