Ouhsc Radiobiology Test 3

Front 1

Hereditary Effects

Back 1

- linear non-threshold relationships (each dose has an effect)
- exposure occurs to the parent, biological effects passed on to progeny

Front 2

How many chromosomes do haploid cells have?

Back 2

23 - form diploid cells

Front 3

When is spermatozoa most radiosensitive in its production cycle?

Back 3

Spermatogonia (0.5 Gy can cause temp sterility)

Front 4

How much radiation causes permanent sterility?

Back 4

5-6 Gy

Front 5

Which is more radioresistant, oocytes or spermatozoa?

Back 5

Oocytes

Front 6

What does radiation to oocytes cause?

Back 6

Premature menopause

Radiation destroys primitive cells in ovarian follicles, which manufacture female sex hormones

Front 7

How many chromosomes do somatic cells have?

Back 7

46

Front 8

What are the exons?

Back 8

Sections of genes containing info that will be translated into proteins for cell function (introns lie in between them)

Front 9

3 Types of Hereditary Diseases

Back 9

Mendelian, Chromosomal, & Multifactorial

Front 10

Radiation & Fruit Flies

Back 10

- Muller, 1927
- induced mutations w/ radiation, effects became cumulative
- low doubling dose estimated

Front 11

Relative Mutation Risk

Back 11

Amount of radiation causing an amount equal to spontaneous mutation rate - doubling dose

Front 12

How have radiation induced effects been measured in humans?

Back 12

- children of atomic bomb survivors (doubling dose estimated at 1.56 Sv)

Front 13

Genetically Significant Dose

Back 13

- dose absorbed by the gonads of persons that will reproduce children
- averaged over entire population (estimated at .5-.7 mSv per person per year)

Front 14

Embryologic Syndromes - Lethal Effects

Back 14

- induced before or immediately after implantation

Front 15

Embryologic Syndromes - Congenital Malformations

Back 15

- specific to organ or system developing at the time of exposure
- expressed after birth

Front 16

What are the primary factors affecting fetal exposure?

Back 16

Fetal age and amount of dose received

Front 17

Pre-Implantation Phase

Back 17

- conception --> 10 days
- irradiation results in increased incidence of spontaneous abortion (either will have great effect or none at all)

Front 18

Organogenesis

Back 18

- 10 days - 6 weeks
- stem cells for major organs are formed
- irradiation can cause newborn death or congenital abnormalities

Front 19

Fetal Stage

Back 19

- 6 weeks - delivery
- irradiation will usually produce congenital abnormalities or no effect
- late effects: leukemia, mental impairment, growth retardation, late-manifesting genetic effects

Front 20

Teratogenic Effect

Back 20

- embryonic defects due to chemical or radiation exposure
- increased risk @ 10 mGy
- causes childhood malignancies, microcephaly, & mental impairment (severe between 8 & 15 weeks exposure), spina bifida, etc
- IQ reduction (exposures of .2 Sv & greater)

Front 21

Telangiectasis

Back 21

- small dilated vessels in skin which may be caused by radiation exposure (spider veins)
- sometimes presented as a birthmark

Front 22

Stochastic (Genetic) Effects

Back 22

Random effects on exposed population

Front 23

What's the US population average of radiation exposure?

Back 23

3.6 mSv

Front 24

Do diagnostic radiation doses large enough to cause deterministic effects?

Back 24

No (exceptions: cardiac/IV studies, early fetus exposure)

Front 25

How are the probability of stochastic effects measured?

Back 25

Through dose, effective dose, & collective effective dose

Front 26

Probability of Stochastic Effects - Dose

Back 26

- refers to absorbed dose when used alone
- measured in rad or Gy (100 rad = 1 Gy)
- doesn't take into account differing sensitivity of body parts or differential exposure

Front 27

Probability of Stochastic Effects - Effective Dose

Back 27

- measured in rem or Sv (100 rem = 1 Sv)
- considers organs & tissues exposed as well as dose (better determinant of stochastic effects)

Front 28

Probability of Stochastic Effects - Collective Effective Dose

Back 28

- considers dose effect on a population
- product of effective dose & number of individuals exposed

Front 29

Angiography Dose

Back 29

- uses high dose fluoro "real time" x-rays
- long term exposures
- contrast media injected into vessel

Front 30

What are some radiation injuries from interventional radiography?

Back 30

Erythema, epilation (hair removal), dry & moist desquamation, late effects [dermal atrophy, telangiectasia, necrosis]

Front 31

Nuclear Medicine Dose

Back 31

- dosage depends on the radiopharmaceuticals administered
- tissues incorporate radioactively labeled compounds, which is then measured

Front 32

PET Dose

Back 32

- most commonly used radiopharmaceutical = FDG
- short half life, low patient dose

Front 33

ICRP

Back 33

International Commission on Radiologic Protection

Front 34

ICRU

Back 34

International Commission on Radiation Units & Measurements

Front 35

NCRP

Back 35

National Council on Radiation Protection & Measurements

Front 36

Who would have the ability to impose radiation regulations in OKC?

Back 36

State regulates & imposes standards (take recommendations from professional organizations)

Front 37

Professional Organizations

Back 37

UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation)
BEIR Committee (Biological Effect of Ionizing Radiation)
EPA (Environmental Protection Agency)
NRC (Nuclear Regulatory Committee)
OSHA (Occupational Safety & Health Administration)
DOE (Department of Energy)

Front 38

Dose (Absorbed Dose)

Back 38

- energy absorbed per unit mass (j/kg)
- rad or Gy

Front 39

Equivalent Dose

Back 39

- absorbed dose w/ consideration of type & energy of radiation
- rem or Sv
- rad x Wr = rem

Front 40

Effective Dose

Back 40

- equivalent dose w/ consideration of tissue type & sensitivity
- rad x Wr x Wt = rem

Front 41

Radiation Weighting Factor (Wr)

Back 41

- used to standardize biologic effects of different types of radiation
- related to the quality of radiation

Front 42

Tissue Weighting Factor (Wt)

Back 42

- relative contribution of each tissue or organ

Front 43

Committed Equivalent Dose

Back 43

- internal sources; deposited radionuclides' radiation amount
- natural sources of radionuclides from food or inhalation; radionuclides from nuc med exams
- dose rate decreases w/ half life

rad/Gy

Front 44

Committed Effective Dose

Back 44

- committed equivalent dose w/ consideration of tissue weighting factors

rem/Sv

Front 45

Collective Equivalent Dose

Back 45

- equivalent dose of a population
- measured in person-Sv

Front 46

Collective Effective Dose

Back 46

- effective dose of a population

Front 47

Collective Committed Effective Dose

Back 47

- effective dose of internally deposited sources in a population

Front 48

What's the max effective dose for a radiation worker?

Back 48

No higher than 50 mSv/yr for any one year

Should average to 20 mSv/yr over a 5-year time span

Front 49

Equation to determine individual worker's lifetime effective dose maximum

Back 49

Person's age x 10 mSv

Front 50

Whole Body Dose

Back 50

250 mrem = 2.5 mSv/quarter

Front 51

Lens of Eye Dose

Back 51

250 mrem = 2.5 mSv/quarter

Front 52

Shallow Skin Dose

Back 52

750 mrem

Front 53

Extremity, non-nuclear

Back 53

1875 mrem

Front 54

Extremity, nuclear pharmacy

Back 54

3750 mrem

Front 55

Fetal Exposure

Back 55

0.5 mSv/month

Front 56

Exposure for People under 18

Back 56

1 mSv/year

Front 57

Emergency Occupational Dose

Back 57

0.5 Sv

Front 58

Nonoccupational Exposure

Back 58

Frequent/Continual - 1 mSv/year

Infrequent - 5 mSv/yr

Front 59

Negligible Individual Dose

Back 59

Annual effective dose 0.01 mSv

Front 60

Radiation Detriment

Back 60

- concept used to quantify the harmful effects of radiation exposure to different body parts
- takes into account severity of disease relative to lethality, loss of quality of life, & years of life lost

Front 61

What subjects does a radiation detriment include?

Back 61

Small component for heritable effects, large component for lethal cancers, allowance for non-lethal cancers

Front 62

ICRP suggested Detriment Adjusted Risk Coefficients for Stochastic effects for a population @ low dose rates

Back 62

5.5% /Sv for cancer
0.2% /Sv for heritable effects
5.7% /Sv total

Front 63

Average Annual Dose to Radiation Workers

Back 63

2 mSv, results in detriment of 1 in 10,000

Front 64

What are the standards for personnel monitoring devices?

Back 64

1) Lightweight, easy to carry
2) Durable enough to tolerate daily use
3) Able to detect small & large exposures
4) Shouldn't be affected by outside influences

Front 65

Film Badge

Back 65

- used to be most commonly used method
- plastic holder holds film & acts as low energy x-ray filter; metal filters (Al & Cu);

Front 66

Film Packet

Back 66

Contains sensitive dosimetry film backed by lead foil to absorb backscatter

Film darkens w/ density which is proportional to amount of exposure

Front 67

What's the film packet's film detection range?

Back 67

10 mrem - 500 rem

Front 68

What's a densitometer do?

Back 68

Used to determine the density & an exposure value

Front 69

Can a film badge discriminate between different types of exposure?

Back 69

Yes, can detect the difference between x-rays, gamma rays, or beta radiation

Front 70

Advantages of a Film Badge

Back 70

- cheap, lightweight, durable, not affected by outside influences
- capable of discriminating between radiation types

Front 71

Disadvantages of a Film Badge

Back 71

Delayed reading time, limited accuracy, movement away from film

Front 72

Pocket Ionization Chambers

Back 72

- measures amount of ionization or air within the chamber
- chamber contains air, 2 electrodes, & a quartz fiber (acts as part of the positive electrode [also the indicator for reading the exposure on a printed scale])

Front 73

What must occur before using a pocket ionization chamber?

Back 73

Device must be "charged" to a predetermined voltage where the quartz fiber will be positioned at 0 on the scale

Front 74

How does a positive electrode become neutral?

Back 74

As the air surrounding the electrode is ionized the quartz fiber acquires the released electrons & becomes more neutrally charged

Front 75

When must a pocket ionization chamber be read by?

Back 75

Must be read same day as exposure (charge can leak away giving false readings)

Front 76

Advantages of Pocket Ionization Chamber

Back 76

Convenient, easy to carry, more accurate & sensitive than film, immediate results

Front 77

Disadvantages of Pocket Ionization Chamber

Back 77

Expensive, must be read daily, no permanent legal record, must be handled carefully

Front 78

Thermoluminescent Dosimeter (TLD)

Back 78

- contain lithium fluoride chips which absorb radiation
- when irradiated electrons within chips are excited to higher energy levels & trapped; when chips are heated, electrons are released & return to original energy levels, giving off excess energy as light

Front 79

How long can a TLD be worn?

Back 79

Up to 3 months

Front 80

Advantages of TLD's

Back 80

Accurate, sensitive, durable, reusable, can be worn up to 3 months

Front 81

Disadvantages of TLD

Back 81

Costs twice as much as film badge, reusable but once heated no record of exposure remains, analyzer must be calibrated to get accurate readings

Front 82

Optically Stimulated Dosimeter

Back 82

- similar to TLD but a laser is used to stimulate release of energy as light
- dose reading obtained faster than TLD
- unaffected by normal temp variations, has longer usable life than TLD

Front 83

Radiation Survey Instruments

Back 83

- used to monitor areas for the presence of radiation & can give a reasonably good estimate of amount
- measures the amount of electrical charge produced in air by ionization within their detection chambers

Front 84

"Cutie Pie" Survey Meter

Back 84

- measures x-rays, gamma & beta radiation
- most often used to measure exposure rates in RF facilities or from radiation therapy patients

Front 85

Geiger-Muller Detector

Back 85

- measures any type of radiation by detecting individual particles or photons
- used in nuc med facilities as an area monitor
- loses calibration quickly; can malfunction when exposed to high intensity radiation

Front 86

Victoreen Condenser R-Meter

Back 86

- measures total exposure in a given period of time using ionization chambers specific to individual exposure ranges
- used for calibrating x-ray equipment