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Biological Aspects
Ch.8 & 9 Biological Aspects of Radiation
| Question | Answer |
|---|---|
| When biologic effects of radiation occur relatively soon after humans receive high doses of ionizing radiation, the biological response demonstrated are called__________. | Early effects |
| T/F Early effects are common in diagnostic imaging. | False. They are not common. |
| The following are factors of __________: -The quantity of ionizing radiation to which the subject is exposed. -The ability of the ionizing radiation to cause ionization of human tissue. -The amount of body area exposed. -The specific body part exposed | Somatic and Genetic Damage |
| When living organisms, such as humans,experience biologic damage from exposure to radiation, the results of this exposure are classified as _____________- | Somatic Effects |
| What are the two classifications of Somatic Effects? | Early and Late |
| If the consequences include cell killing and are directly related to the dose received, they are termed________. | Deterministic Somatic Effects |
| As the radiation dose increases, the severity of early deterministic somatic effects ___________. | Also increases |
| A point at which results begin to appear and below which they are absent is know as a _________________. | threshold |
| The amount of biologic damage depends on_____________. | the actual absorbed dose of ionizing radiation |
| Early deterministic somatic effects depend on the time of exposure to ionizing radiation. How long does it take for them to appear? | Minutes, Hours, Days, and/or Weeks |
| Some possible effects of high-dose consequences in early deterministic effects include: | Nausea, fatigue, Erythema, Epilation, Blood Disorders, Intestinal disorders, Fever, Shedding of outer layer of skin, Depressed sperm count, temporary or permanent sterility in both male and female, and injury to central nervous system |
| This occurs in humans after whole-body reception of large doses of ionizing radiation delivered over a short period of time. | Acute Radiation Syndrome, ARS, radiation sickness |
| A medical term that defines a collection of symptoms. | Syndrome |
| Name the three separate dose-related syndromes that occur as part of the total body Acute Radiation Syndrome: | Hematopoietic Syndrome Gastrointestinal Syndrome Cerebrovascular Syndrome |
| What is another name for Hematopoietic Syndrome? | Bone marrow syndrome |
| How long could death occur after exposure of a whole body dose of 2Gyt? | 6 to 8 weeks |
| This syndrome can occur after whole-body exposure of 1-10Gyt | Hematopoietic Syndrome |
| What can happen to the body if the hematopoietic system is exposed to a whole-body dose of radiation? | Cause the number of red blood cells, white blood cells, and platelets in the blood to decrease; May also damage cells in other organs and cause the affected organ or organs to fail |
| Why could the body be more susceptible to hemorrhaging if the hematopoietic system is damaged due to excessive radiation? | Because the number of platelets decrease with the loss of bone marrow function, the body loses its ability to clot blood |
| What happens to the body when the cells of the lymphatic system are damaged? | The body cannot combat infection |
| In humans, this form of ARS appears at a threshold dose of approximately 6Gyt and peaks after a dose of 10Gyt. | Gastrointestinal Syndrome |
| If a person is exposed to doses of 6Gyt to 10Gyt what is the life expectancy after exposure? | 3 to 10 days |
| What happens to the body during the latent period? How long can it last? | Nothing the symptoms seem to disappear. 5 days. |
| Why does death occur during the Gastrointestinal Syndrome? | The catastrophic death to the epithelial cells that line the gastrointestinal tract. |
| Why could a person die as a result of Gastrointestinal Syndrome? | infection, fluid loss, electrolytic balance, or sometimes by damage to the bone marrow |
| What part of the body is most severely affected part of the gastrointestinal tract? | Small intestine |
| What form of ARS results when the central nervous system and the cardiovascular system receive a dose of 50Gyt or more? | Cerebrovascular Syndrome? |
| What does ARS stand for? | Acute Radiation Syndrome |
| A dose of 50Gyt or more can cause death within? | A few hours to 2 to 3 days |
| How long is the latent period with Cerebrovascular Syndrome? | Up to 12 hours |
| What are the major response stages of Acute Radiation Syndrome? | Prodromal (initial) Latent period Manifest illness Recovery or death |
| This response stage occurs within hours after a whole body absorbed dose of 1 Gyt or more. | Prodromal,or initial stage |
| This response stage lasts approximately 1 week, no visible symptoms occur. During this stage recovery begins or lethal effects begin. | Latent period |
| This response stage is the period where signs and symptoms that affect the Hematopoietic, gastrointestinal, and cerebrovascular systems become visible. | Manifest Stage |
| This method of assesment uses biological samples, usually taken from individuals who have been exposed to radioactive materials | Biologic Dosimetry |
| What does LD 50/30 mean? | Signifies the whole-body dose of radiation that can be lethal to 50% of the exposed population within 30 days |
| Cells contain a repair mechanism inherent in their biochemistry called ____________. | Repair enzymes |
| What can occur when cells are exposed to sublethal doses of ionizing radiation? | Repair and Recovery |
| What percentage of radiation-induced damage is irreparable? | approximately 10% |
| What percentage of radiation-induced damage can be repaired over time? | 90% |
| A destructive response in biologic tissue can occur_____________. | when any part of the human body receives a high radiation dose |
| Shrinkage of organs and tissues is called______. | Atrophy |
| Organ and tissue response to radiation exposure depends on factors such as: | Radiosensitivity Reproductive characteristics Growth Rate |
| Some local tissues suffer immediate consequences from high radiation doses, examples include: | Skin Male and Female reproductive organs Bone Marrow |
| What is radiodermatitis? | A significant reddening of the skin caused by excessive exposure to ionizing radiation |
| The skin consists of three layers: | Epidermis (outer) Dermis (middle) Hypodermis (bottom layer, fat and tissue) |
| Hair follicles, sensory receptors, sebaceous glands, and sweat glands are all considered what type of structure? | Accessory |
| This can be caused when individuals are exposed to radiation because hair follicles are growing tissue. | Epilation or hair loss |
| A _________is a permanent alteration in the DNA sequence that makes up a gene. | |
| The testes of the male and the ovaries of the female do not respond in the same way to irradiation because_______________. | of the difference in the way that these cells are produced and progress |
| Which type of cells constantly reproduce? | spermatogonia, the stem cells of the testes |
| In the female, the oogonia, the ovarian stem cells, multiply to millions of cells only during fetal development, before birth, and then ________________. | Steadily decline in number throughout life |
| The study of genetics with an emphasis on cell chromosomes | cytogenetics |
| A cytogenetic analysis of chromosomes may be accomplished through the use of a chromosome map called a | karyotype |
| This is the phase of cell division in which chromosome damage caused by radiation exposure can be evaluated | Metaphase |
| Only a very small percentage of chromosome breakage occurs from ______________________ on a macromolecule such as DNA | the direct action of ionizing radiation |
| The most radiosensitive vital organ system in human beings? | Hematopoietic |
| Radiation-induced damage at the cellular level may lead to measurable somatic and hereditary damage in the living organism as a whole later in life, this is called_______. | Late effects |
| Some examples of measurable late biologic damage are: | Cataracts, Leukemia, and Genetic Mutations |
| Cataracts is considered to be a ______________ effect | deterministic |
| Leukemia and Genetic Mutations are considered to be ______________ consequences | Stochastic |
| A science that deals with the incidence, distribution, and control of disease in a population | Epidemiology |
| This type of study consists of observations and statistical analysis of data, such as the incidence of disease within a group of people | Epidemiologic Studies |
| The radiation dose response relationship is demonstrated graphically through a curve that maps_______________? | observed effects of radiation exposure in relation to the dose of radiation received. |
| A point at which a response or reaction to an increasing stimulation first occurs | Threshold |
| What does threshold mean in reference to ionizing radiation? | That below a certain radiation level or dose, no biologic effects are observed. |
| _________________ begin to occur only when the threshold level or dose is reached. | Biologic effects |
| This relationship indicates that any radiation dose has the capability of producing a biologic effect. | Nonthreshold |
| What does it mean If ionizing radiation is the stimulus & the biologic effect is its response, if a nonthreshold relationship exists between radiation dose & a biologic response, some biologic effects will be caused in organisms by even the smallest dose? | No radiation dose can be considered absolutely "safe" |
| This term states that the equation that best fits the data has components that depend on dose to the first power (linear or straightline behavior) and also dose squared (quadratic or curved behavior). | Linear-quadratic |
| The BEIR Committee recommends the use of the ______________of radiation dose-response for most types of cancers. | Linear nonthreshold curve |
| This term implies that the chance of a biologic response to ionizing radiation is DIRECTLY proportional to the dose received | Linear nonthreshold (LNT) curve |
| The linear-quadratic nonthreshold curve (LQNT) estimates: | The risk associated with low-level radiation |
| What health concerns are presumed to follow the linear-quadratic nonthreshold curve? | Leukemia Breast Cancer Heritable Damage |
| Deterministic effects of significant radiation exposure such as skin erythema and hematologic depression may be demonstrated using what curve? | Linear threshold dose-response curve |
| What does a linear threshold dose-response curve show? | That a biologic response does not occur below a specific dose level |
| What type of threshold is generally employed in radiation therapy to demonstrate high-dose cellular response to radiation within specific tissues such as skin, lens of the eye, and various types of blood cells? | Sigmoid, S-shaped (nonlinear), threshold curve |
| The _________ of the Sigmoid, S-shaped (nonlinear) threshold curve indicates that the limited recovery occurs at lower radiation dose | Tail |
| At the highest radiation doses, the curve________________ and then veers downward because the affected living specimen or tissue dies before the observable effect appears | gradually levels off |
| When living organisms that have been exposed to radiation sustain biologic damage, the effects of this exposure are classified as | somatic effects |
| An example of _______________ effect is irradiation of an individual's genetic material (sperm or eggs) leading to a genetic malformation in offspring. | non-somatic |
| The classification of somatic effects may be subdivided into two categories: | Stochastic effects Deterministic effects |
| In _________ effects, the probability that the effect happens depends upon the received dose, but the severity if the effect does not. | stochastic |
| The occurrence of a ___________ is an instance of a stochastic somatic effect. | Cancer |
| In deterministic effects, however, both the probability and the severity of the effect depend upon ___________. | the dose |
| An example of a deterministic somatic effect is a______________. | cataract |
| These effects are consequences of radiation exposure that appear months or years after such exposure. | Late somatic effects |
| Slowly developing changes to the body from radiation exposure received is classified as | Late Deterministic Somatic Effects |
| Late responses in the body to radiation exposure that do not have a threshold, occur in an arbitrary or probabilistic manner, and have a severity that does not depend on dose are classified as: | Late stochastic effects |
| The ________ risk model predicts that a specific number of excess cancers will occur as a result of exposure. | Absolute |
| The ________ risk model predicts that the number of excess cancers will increase as the natural incidence of cancer increases with advancing age in a population | Relative |
| Biologic effects of ionizing radiation on future generations are termed___________. | genetic (heredity) effects |
| Mutations in genes and DNA that occur at random as a natural phenomenon are called__________________. | spontaneous mutations |
| __________ attempt to repair cellular damage by mending structural breaks in chromosomes that have been hit by ionizing radiation. | Enzymes |
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