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86 Cards in this Set

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  • Back
Hereditary Effects
- linear non-threshold relationships (each dose has an effect)
- exposure occurs to the parent, biological effects passed on to progeny
How many chromosomes do haploid cells have?
23 - form diploid cells
When is spermatozoa most radiosensitive in its production cycle?
Spermatogonia (0.5 Gy can cause temp sterility)
How much radiation causes permanent sterility?
5-6 Gy
Which is more radioresistant, oocytes or spermatozoa?
What does radiation to oocytes cause?
Premature menopause

Radiation destroys primitive cells in ovarian follicles, which manufacture female sex hormones
How many chromosomes do somatic cells have?
What are the exons?
Sections of genes containing info that will be translated into proteins for cell function (introns lie in between them)
3 Types of Hereditary Diseases
Mendelian, Chromosomal, & Multifactorial
Radiation & Fruit Flies
- Muller, 1927
- induced mutations w/ radiation, effects became cumulative
- low doubling dose estimated
Relative Mutation Risk
Amount of radiation causing an amount equal to spontaneous mutation rate - doubling dose
How have radiation induced effects been measured in humans?
- children of atomic bomb survivors (doubling dose estimated at 1.56 Sv)
Genetically Significant Dose
- dose absorbed by the gonads of persons that will reproduce children
- averaged over entire population (estimated at .5-.7 mSv per person per year)
Embryologic Syndromes - Lethal Effects
- induced before or immediately after implantation
Embryologic Syndromes - Congenital Malformations
- specific to organ or system developing at the time of exposure
- expressed after birth
What are the primary factors affecting fetal exposure?
Fetal age and amount of dose received
Pre-Implantation Phase
- conception --> 10 days
- irradiation results in increased incidence of spontaneous abortion (either will have great effect or none at all)
- 10 days - 6 weeks
- stem cells for major organs are formed
- irradiation can cause newborn death or congenital abnormalities
Fetal Stage
- 6 weeks - delivery
- irradiation will usually produce congenital abnormalities or no effect
- late effects: leukemia, mental impairment, growth retardation, late-manifesting genetic effects
Teratogenic Effect
- 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)
- small dilated vessels in skin which may be caused by radiation exposure (spider veins)
- sometimes presented as a birthmark
Stochastic (Genetic) Effects
Random effects on exposed population
What's the US population average of radiation exposure?
3.6 mSv
Do diagnostic radiation doses large enough to cause deterministic effects?
No (exceptions: cardiac/IV studies, early fetus exposure)
How are the probability of stochastic effects measured?
Through dose, effective dose, & collective effective dose
Probability of Stochastic Effects - Dose
- 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
Probability of Stochastic Effects - Effective Dose
- measured in rem or Sv (100 rem = 1 Sv)
- considers organs & tissues exposed as well as dose (better determinant of stochastic effects)
Probability of Stochastic Effects - Collective Effective Dose
- considers dose effect on a population
- product of effective dose & number of individuals exposed
Angiography Dose
- uses high dose fluoro "real time" x-rays
- long term exposures
- contrast media injected into vessel
What are some radiation injuries from interventional radiography?
Erythema, epilation (hair removal), dry & moist desquamation, late effects [dermal atrophy, telangiectasia, necrosis]
Nuclear Medicine Dose
- dosage depends on the radiopharmaceuticals administered
- tissues incorporate radioactively labeled compounds, which is then measured
PET Dose
- most commonly used radiopharmaceutical = FDG
- short half life, low patient dose
International Commission on Radiologic Protection
International Commission on Radiation Units & Measurements
National Council on Radiation Protection & Measurements
Who would have the ability to impose radiation regulations in OKC?
State regulates & imposes standards (take recommendations from professional organizations)
Professional Organizations
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)
Dose (Absorbed Dose)
- energy absorbed per unit mass (j/kg)
- rad or Gy
Equivalent Dose
- absorbed dose w/ consideration of type & energy of radiation
- rem or Sv
- rad x Wr = rem
Effective Dose
- equivalent dose w/ consideration of tissue type & sensitivity
- rad x Wr x Wt = rem
Radiation Weighting Factor (Wr)
- used to standardize biologic effects of different types of radiation
- related to the quality of radiation
Tissue Weighting Factor (Wt)
- relative contribution of each tissue or organ
Committed Equivalent Dose
- 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

Committed Effective Dose
- committed equivalent dose w/ consideration of tissue weighting factors

Collective Equivalent Dose
- equivalent dose of a population
- measured in person-Sv
Collective Effective Dose
- effective dose of a population
Collective Committed Effective Dose
- effective dose of internally deposited sources in a population
What's the max effective dose for a radiation worker?
No higher than 50 mSv/yr for any one year

Should average to 20 mSv/yr over a 5-year time span
Equation to determine individual worker's lifetime effective dose maximum
Person's age x 10 mSv
Whole Body Dose
250 mrem = 2.5 mSv/quarter
Lens of Eye Dose
250 mrem = 2.5 mSv/quarter
Shallow Skin Dose
750 mrem
Extremity, non-nuclear
1875 mrem
Extremity, nuclear pharmacy
3750 mrem
Fetal Exposure
0.5 mSv/month
Exposure for People under 18
1 mSv/year
Emergency Occupational Dose
0.5 Sv
Nonoccupational Exposure
Frequent/Continual - 1 mSv/year

Infrequent - 5 mSv/yr
Negligible Individual Dose
Annual effective dose 0.01 mSv
Radiation Detriment
- 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
What subjects does a radiation detriment include?
Small component for heritable effects, large component for lethal cancers, allowance for non-lethal cancers
ICRP suggested Detriment Adjusted Risk Coefficients for Stochastic effects for a population @ low dose rates
5.5% /Sv for cancer
0.2% /Sv for heritable effects
5.7% /Sv total
Average Annual Dose to Radiation Workers
2 mSv, results in detriment of 1 in 10,000
What are the standards for personnel monitoring devices?
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
Film Badge
- used to be most commonly used method
- plastic holder holds film & acts as low energy x-ray filter; metal filters (Al & Cu);
Film Packet
Contains sensitive dosimetry film backed by lead foil to absorb backscatter

Film darkens w/ density which is proportional to amount of exposure
What's the film packet's film detection range?
10 mrem - 500 rem
What's a densitometer do?
Used to determine the density & an exposure value
Can a film badge discriminate between different types of exposure?
Yes, can detect the difference between x-rays, gamma rays, or beta radiation
Advantages of a Film Badge
- cheap, lightweight, durable, not affected by outside influences
- capable of discriminating between radiation types
Disadvantages of a Film Badge
Delayed reading time, limited accuracy, movement away from film
Pocket Ionization Chambers
- 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])
What must occur before using a pocket ionization chamber?
Device must be "charged" to a predetermined voltage where the quartz fiber will be positioned at 0 on the scale
How does a positive electrode become neutral?
As the air surrounding the electrode is ionized the quartz fiber acquires the released electrons & becomes more neutrally charged
When must a pocket ionization chamber be read by?
Must be read same day as exposure (charge can leak away giving false readings)
Advantages of Pocket Ionization Chamber
Convenient, easy to carry, more accurate & sensitive than film, immediate results
Disadvantages of Pocket Ionization Chamber
Expensive, must be read daily, no permanent legal record, must be handled carefully
Thermoluminescent Dosimeter (TLD)
- 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
How long can a TLD be worn?
Up to 3 months
Advantages of TLD's
Accurate, sensitive, durable, reusable, can be worn up to 3 months
Disadvantages of TLD
Costs twice as much as film badge, reusable but once heated no record of exposure remains, analyzer must be calibrated to get accurate readings
Optically Stimulated Dosimeter
- 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
Radiation Survey Instruments
- 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
"Cutie Pie" Survey Meter
- measures x-rays, gamma & beta radiation
- most often used to measure exposure rates in RF facilities or from radiation therapy patients
Geiger-Muller Detector
- 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
Victoreen Condenser R-Meter
- measures total exposure in a given period of time using ionization chambers specific to individual exposure ranges
- used for calibrating x-ray equipment