Radiation protection Somatic Effects

Radon
A colorless, odorless, heavy radioactive gas that is a decay product of uranium
Carcinogens
cancer-causing agents
Carcinogenesis
The development of cancer
Carcinomas
solid tumors that start in the epithelial tissue; one of the two major categories of cancers
Gene
The basic unit of heredity.

A specific section on a chromosome, the DNA double helix that contains a specific sequence of nitrogenous organic bases that is related to a particular characteristic.

Gene amplification
The over-expression of a gene that occurs when there are extra copies of the proto-oncogene in a cell.
Gene p53
A key suppressor gene; unlike other suppressor genes, gene p53 also kills malignant cells.
Leukemia
Literally, white blood; a neoplastic overproduction of white blood cells.
Oncogenes
Genes that direct a cell to function abnormally.

Point mutations
The genetic mutation that results when a single base pair in the DNA strand is lost or changed.
Proto-oncogenes
The source of oncogenes; present in all mammalian cells, proto-oncogenes participate in normal cell growth.
Reciprocal translocation
A multi-hit aberration in which the tops of adjacent chromosomes are broken and the resulting fragments attach to one another, possibly resulting in the alteration of some genetic information the most common form of radiation-induced chromosomal abnormalities may not necessarily result in cell death.
Sarcomas
Cancers that begin in connective tissue; one of the two major categories of cancers.
Somatic cells
Refers to all the cells in the human body except the germ cells (genetic cells).
Suppressor genes
Genes that suppress the replication of malignant cells.
Somatic effects
A somatic effect is biologic damage to the exposed individual caused by exposure to ionizing radiation.

Early somatic effects
Effects that appear within minutes, hours, days or weeks after exposure to ionizing radiation.
Late somatic effects
Effects that appear months, years, or decades after exposure to ionizing radiation. May result from previous whole or partial body high radiation doses, or they may be the product of individual low-level doses sustained over the years.
Nonstochastic effects (deterministic)
Biological somatic effects of ionizing radiation that can be directly related to the dose received. Require a threshold dose. Does not occur below the threshold dose.

Above the threshold, the severity of the biologic damage increases as the dose increases.

Nonstochastic (deterministic) early effects
Nausea, fatigue, intestinal disorders, desquamation, erythema, epilation, hematologic depression, reduced fertility/sterility, central nervous system damage
non-stochastic (deterministic) late effects
Cataracts, life span shortening, fibrosis, organ atrophy, reduced fertility/sterility, loss of parenchymal cells (the functional cells of an organ)
Stochastic effects (probabilistic)
Mutational, nonthreshold, randomly occuring biological somatic changes in which the chance of occurrence of the effect rather than the severity of the effect is proportional to the dose of ionizing radiation. This means that the effect occurs randomly and the severity of the effect is not dose dependent- the chance of occurrence is proportional to the dose. Example: the more radiation exposure – the greater the odds of developing cancer.
Stochastic (probabilistic) effects (late only)
Carcinogenesis and embryologic effects or birth defects
Ring formation
the formation that results when the ends of a severed chromosome join and form a ring-generally results in cell death
Dicentric
A chromosome with two centromeres-generally results in cell death.
Acentric
A chromosome fragment that has no centromere
Reciprocal translocation aberration
A multi-hit aberration in which the tops of adjacent chromosomes are broken and the resulting fragments attach to one another. The most common form of the radiation-induced chromosomal abnormalities-may not necessarily result in cell death.

Associated with an increase in certain types of cancer.

Cancer
The most important late stochastic somatic effect caused by exposure to ionizing radiation. The end result of a series of events occurring within a cell, not a single event.

May stay in one location or metastasize.

Genetic effects
When a damaged sperm or ovum combines with another reproductive cell, the mutation can be transmitted to future generations.
The greater the radiation exposure dose
the greater the probability of cancer
What cells can become cancerous?
All human cells, although it is more common in certain parts of the body
Cancer is characterized by:
uncontrolled growth and spread of abnormal cells. Cells produce more rapidly.
Relative Risk
Risk model used to estimate late radiation effects on large populations when there is no precise knowledge of the radiation dose; it predicts a percentage increase in incidence.
Latent period
The period between the interaction with a cancer-causing agent and the expression of the cancer.
Extensive personal radiation protection procedures should be followed by radiographers because:
A link has been established between radiation exposure and cancer.
Population group with the highest risk of developing cancer
Men
What is the risk of developing cancer from the level of radiation exposure received during diagnostic imaging procedures?
extremely low
Committee on the Biological Effects of Ionizing Radiation
Group that directs many of the risk studies related to radiation exposure
Most common cause of skin cancer
Over-exposure to sun and ultraviolet light
Primary types of carcinogens are
chemicals and radiation
Is the severity of cancer dose dependent
No
Do the diagnostic benefits of radiography outweigh any possible risk of radiation-induced cancer
Yes
Latent period of a solid tumor
20 to 50 years
How is gene p53 different from other genes
it suppresses and kills tumors
Approx how many diseases are grouped under the term cancer?
100
What are the most common sites for cancer to develop?
Blood-forming tissue, lymphatic system, skin, uterus
Which radiation dose-response relationship does Leukemia and breast cancer follow?
linear-quadratic radiation dose response relationship
Why are the normal expectations of cancer higher among men than women?
Men smoke more than women, men face more occupational hazards
Why are the risk of developing cancer greater in someone exposed to ionizing radiation when young rather than old?
With older individuals, natural death may occur before the end of the latent period.
Normal activity of cancer
Remains in one place in the body and spreads to other parts of the body through the bloodstream or lymphatic system
How can radiation exposure activate oncogenes?
Through gene amplification, by chromosomal reciprocal translocation, from a point mutation
1 in 9
the probability of a woman developing breast cancer
What is the number one cancer killer
Lung Cancer
Normal latent period for thyroid cancer
10 to 20 years
5%
The approximate percentage of cancers that can be traced to occupational exposure to chemicals or environmental pollution
What dose of ionizing radiation does not increase the probability of developing cancer?
What is the overall 5-year survival rate of persons with lung cancer?
13%
What increases the risk of breast cancer for women?
Age over 50, previous case of breast cancer, childlessness (nulliparity), first child after 30
Absolute Risk
The prediction of cancer risk following radiation exposure in a certain population; a specific number of excessive malignancies will occur due to the dose
What percentage of cancers results from teh exposure to carcinogens or hereditary genetic mutations
Approx 80%
What dose response relationship does cancer follow?
linear-nonthreshold
x

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