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Chapter 9 Late Deterministic and Stochastic Radiation Effects

Terms in this set (100)

late effects
are the long term results of radiation exposure
Examples of late biologic damage are:
Cataracts, Leukemia, Genetic mutations
Cataracts
deterministic effect
Leukemia and Genetic mutations
stochastic consequences
Epidemiology
as a "science that deals with the incidence, distribution, and control of disease in a population"
Many causes of radiation-induced skin cancer among radiation workers in the early _____ were documented.
1900s
Exposed populations provided proof that high radiation doses can certainly induce ____ n humans
cancer
Low radiation doses are not actually ______
measurable
Radiobiologists engaged in research have a common goal to establish_______
relationships between radiation and dose reponse
The information obtained can be used to _____ to predict the rick of occurrence of malignancies in human populations that have been exposed to low levels of ionizing radiation.
attemp
Radiation dose-response relationship
is demonstrated graphically through a curve that maps the observed effects of radiation exposure in relation to the dose of radiation received
Threshold
may be defined as a point at which a response or reaction to an increasing stimulation first occurs
Nonthreshold
relationship indicates that any radiation dose has the capability of producing a biologic effect
Linear nonthreshold curve
of radiation dose-response for most types of cancers and the committee recommends the use
LNT
implies that the chance of a biologic response to ionizing radiation is directly proportional to the dose received
Example of LNT
if the absorbed dose is doubled, the biologic response probability, and therefore its actual occurrence in a large population sample is also doubled
linear-quadratic nonthreshold curve LQNT
estimates the risk associated with low-level radiation and the curve to be a more accurate reflection of stochastic and genetic effects at low-dose levels from low-LET radiation
The following health concerns are presumed to follow this LQNT:
Leukemia, breast cancer, heritable damage
The regulatory agencies have chosen to be ______ that is, to use a model that may overestimate risk but is not expected to underestimate risk
conservative
sigmond, or S- shaped nonlinear threshold curve
of the radiation dose-response relationship is generally employed in radiation therapy to demonstrate high-dose cellular response to the radiation within specific tissues such as skin, lens of the eye, and various types of blood cells
somatic effects
when living organisms that have been exposed to radiation sustain biologic damage, the effects of this exposure are classified
Example of a non-somatic effect is
irradiation of an individual's genetic material leading to a genetic malformation in offspring
The classification of somatic effects may be subdivided into:
Stochastic effects
Deterministic effects
Stochastic effects the probability that the effect happens depends upon the received dose, but
the severity of the effect does not
Deterministic effects both the probability and the severity of the effect depend upon____
the dose
An example of a deterministic somatic effect is a____
cataract
The ___ radiation absorbed dose to the lens of the eye, the worse the cataract will become
more
_______ exists that low-level ionizing radiation doses below _____ Sv cause a significant increase in the risk of malignancy.
No conclusive proof, 0.1
3 categories of adverse health consequences require study at low levels of exposures:
cancer induction
damage to the unborn from irradiation in utero
genetic effects
Late deterministic effects are not likely to occur from
diagnostic imaging procedures
Late stochastic effects could be initiated by even the _______ exposure if many low probability occurrences were to be simultaneously realized
smallest amount of radiation
The 3 major types of late effects are:
Carcinogenesis
Cataractogenesis
Embryologic effects
Doses as low as 0.1 Sv in groups of occupationally exposed individuals and virtually all patients the risk is
not directly measurable in population studies
Absolute risk
model predicts that a specific number of excess cancers will occur as a result of exposure
Relative risk
model predicts that the # of excess cancers will increase as the natural incidence of cancer increases with advancing age in a population
Cancer
is the most imp0rtant late stochastic effect caused by exposure to radiation
Carcinogenesis
this effect is a random occurrence that does not seem to have a threshold and for which the severity of the disease is not dose related
Radium Induced Cancer
distinguishing its physical appearance is difficult b/c it does not appear different form cancers initiated by other agents
Radium Watch Dial Painters
followed this procedure unfortunately ingested large quantities of radium
Radium
it is chemically similar to calcium and incorporated into bone tissue
Radium caused for the watch dial painters:
Osteoporosis
Osteogenic sarcoma
Carcinoma
Radium's Z number is?
88 and half life is 1622 years
The bones most frequently affected by cancer included the______.
pelvis, femur, mandible
Doses of _ Gy or more are _____ to have induced the aforementioned malignancies.
5; assumed
How many women in the industry were there?
1474
How many were diagnosed with cancer of paranasal sinuses?
61
How many were diagnosed with cancer of the materiod air cells?
21
Studies attributed the death of at least __ of the radium poisoning.
18
Uranium
a radioactive element with a very long half-life of 4.5 million years and decays through a series of radioactive nuclides by emitting alpha, beta and gamma radiation
Radon's Z #?
86 and half-life of 3.8 days
How much percentage of the European Uranium miners a late stochastic effect of lung cancer?
50 %
Navojo people and white workers got approximately lent dose of?
10 Sv or more
The result of the alarmingly high # of American Uranium miners died of what?
cancer and other respiratory diseases
What did the American Uranium miners do after work when they went home and caused a risk of radiation?
they did not change their work clothes on returning home b/c the clothes were radiocactive material, and the families were extremely vulnerable to radiation cancers
Who were the early medical radiation workers that were exposed at large amounts of radiation without realizing the dangers of it?
radiologists, dentists, technologists
When compared with their nonradiologist counterparts, substantial numbers also had a higher incidence of blood disorders such as:
Aplastic anemia, Leukemia
Today, as a result of programs stressing radiation safety education, appropriate use of ________, radiation workers employed in medical imaging need not experience any adverse health effects as a consequence of their work.
protective devices, improvements in x-ray imaging equipment
Thorotrast
between 1925 and 1945 it was used as a contrast agent of diagnostic angiography and by weight is 25 % thorium dioxide
Patients injected with contrast agent Thorotrast by?
intravascular injection
What was the primary recipients for this Thorotrast?
liver, spleen
After the latent period of 15 to 20 years with Thorotrast, the cumulative destruction wrought by the alpha particle- emitting contrast agent resulted in many cases of:
liver cancer, spleen cancer, angiosarcomas, biliary duct carcinomas
During what years did the infants were treated for an enlarged Thymus gland with radiation?
1940s and early 1950s
The Thymus gland enlargement in many infants with what?
respiratory distress
To treat for the large Thymus gland, the doses was of x-radiation?
1.2 to 60 Gy
Some 20 years later what started happen to the infants that were treated with this much x-radiaiton?
thyroid noducles and carcinomas
Patients treated with radiation for the relief of mastitis and also put radiation on the health breast tissue too help indicate that?
that radiation can cause breast cancer
In a study of 531 women who received a mean dose of -____ cGy
247
'breast cancer incidence doubled from___ expected to ___ actual."
3.2%, 6.3%
Mammography
performed for either screening or diagnostic purposes could possibly cause the development of breast cancer
Rongelap Atoll recieved a mean dose of radiation to the thyroid gland of ____ Gy
21
Utrik Atoll recieved ___ Gy
2.80
The dose of __ Gy is considered to be the population average dose for these 2 areas combined
12
The 300,000 people living in these 2 cities at the time of these bombings, _____ were killed and ____ were injured
88,000; 70,000
Epidomiologic date about the Hiroshima atomic bomb survivors also indicate that a linear relationship exits between what?
radiation dose and radiation induced leukemia
Available information of the kind necessary to establish the existence of a _______
threshold dose response relationship
However, when more recent studies revealed that the uranium fueled bomb dropped on Hiroshima provided more ____ exposure and less ____ exposure then believed.
gamma radiation, neutron
If the evacuees are monitored for at least 30 years, important estimates of radiation induced leukemias, thyroid cancers, and other malignances ___ obtained
may be
10 days after the Chernobyl accident, more than __ countries received fallout
20
more than ___ people recieved from the fallout of the Chernobyl accident
400,000
Dr. Richard Wilson estimated what?
that about 200.000 people throughout the world will develop a radiation induced malignancy form the Chernobyl accident
Iodine-131 ( half life- 8 days)
was to help prevent Thyroid cancer but don't accidental overdose it the physicians use potassium iodide to children in Poland and other countries after Chernobyl
The appearance of such radiation-induced thyroid malignancies is usually ___ years after exposure
10 to 20
What will induce the formation of cataracts?
2 Gy
What is the lowest dose of Gy that cataracts maybe induced?
0.1
Radiation induced cataracts in humans follow a _____ relationship
threshold, nonlinear dose response
Gestation in humans is divided into 3 stages:
-Preimplantation- 0 to 9 days after sex
-Organogenesis- 10 days to 12 weeks after sex
-Fetal stage- 12 weeks to term
First trimester is the most crucial period b/c why?
the embryo fetus contains a large # of stem cells during this period of gestation
Preimplantation stage
the fertilized ovum divides and forms a ball like structure containing undifferentiated cells
If the ball like structure in the preimplantation stage is irradiated with a dose of?
.05 to .15 Gy embryonic death will occur
Organogenesis
occurs at approx. 10 days to 12 weeks after sex the developing fetus is most susceptible to radiation congenital abnormalities during this period
Genetic effects
biologic effects of ionizing radiation on future generations are termed by and responses occur as a result of radiation induced damage to the DNA molecule in the sperm or ova of an adult
Spontaneous mutations
mutations in genes and DNA that occur at random as a natural phenomenon
Spontaneous mutations in human genetic material cause wide variety of disorders or diseases:
hemophilia, huntington's disease, down syndrome, duchenne's muscular dystrophy, sickle cell amenia, cystic fibrosis, hydrocephalus
A hereditary disorder is present in approx. ___ of all live births in the USA.
10%
Certain agents can increase the frequency of mutations. Some of these include:
Elevated temperatures
Ionizing radiation
Viruses
Absorption of certain chemicals
Point mutations
genetic mutations at the molecular level
That even the smallest radiation dose could cause some hereditary damage, there is ______ gonadal radiation dose.
no such thing as a 100% safe
Existing data on radiation induced genetic effects in humans are both what?
contradictory and inconclusive
Doubling dose
is the radiation dose that cause the # of spontaneous mutations occuring in a given generation to increase to 2 times their original #
The radiation doubling equivalent dose for humans, determined by the studies of the children of Hiroshima and Nagasaki bombing, is estimated to have a mean value of ___ Sv based on the hereditary indicators of untoward what?
1.56-- pregnancy outcome, childhood mortality, sex chromosome aneuploidy
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