Early Radiation Effects on Organ Systems Flashcards
Definition of somatic effects
Biologic damage experienced by living organisms (such as humans) as a result of exposure to ionizing radiation.
Depending on the length of time from the moment of irradiation to the first appearance of symptoms of radiation damage, the effects are classified as either:
Late somatic effect or early somatic effects.
Effects of ionizing radiation that appear within minutes, hours, days, or weeks of high doses; also called acute effects.
Early somatic effects
Data concerning early somatic effects of ionizing radiation derived from:
laboratory animal studies and irradiated human populations.
Non-genetic effects that appear months or years following exposure to ionizing radiation:
Late somatic effects
Somatic and genetic damage factors:
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 parts exposed.
Ionizing radiation produces the greatest amount of biologic damage in the human body when:
a large dose of densely ionizing radiation (high-LET) is delivered to a large or radiosensitive area of the body.
If the consequences of irradiation include cell killing and are directly related to the dose received, they are termed:
deterministic somatic effects.
These effects have a threshold, a point at which they begin to appear and below which are absent.
deterministic somatic effects.
The amount of deterministic somatic effects depends on:
the absorbed dose.
Depending on the exposure, early deterministic somatic effects appear within:
minutes, hours, days or weeks.
Severity of early deterministic somatic effects is:
dose-related.
High dose early deterministic somatic effects include:
nausea fatigue erythema epilation (loss of hair) blood disorders intestinal disorders fever dry and moist desquamation depressed sperm count temporary or permanent sterility in male and females injury to CNS (extremely high doses)
When the whole body is exposed to a dose of _____, many of the manifestations of early deterministic somatic effects occur in succession and may be related to the cellular effects discussed in previous chapter.
6 Gy(t) (600 rad)
Occurs in humans after whole body reception of large doses of ionizing radiation delivered over a short period of time.
Acute Radiation Syndrome (ARS). (This is a result from something as large as a nuclear disaster…not medical imaging.)
Data about ARS has been obtained from epidemiological studies of:
Atomic bomb survivors of Hiroshima and Nagasaki
Marshall Islands
Nuclear radiation accident victims (‘86 Cherynobyl disaster)
Radiation therapy patients
The clinical signs and symptoms of ARS present themselves in four stages:
The prodromal stage
The latent period
The manifest illness (or acute stage)
Death
The three possibilities of manifest illnesses of ARS include:
Hematologic syndrome
Gastrointestinal syndrome
CNS syndrome
Also called “initial stage.”
Immediate response of ARS.
Means “running before” and refers to the initial stage of the disease.
May last from a few hours to a couple of days.
Severity of symptoms is dose related.
Immediate response of radiation sickness.
Prodromal Stage
Individuals who are exposed to radiation levels greater than ____ usually show prodromal symptoms which include varying degrees of nausea, vomiting and diarrhea and a reduction in the white blood cells of the circulating blood (leukopenia)
1 Gy(t) (100 rad)
The time between the exposure and the onset of prodromal symptoms is an indication of the:
magnitude of the exposure. At higher doses, the duration of the prodromal stage becomes shorter until it may be difficult to separate it from the manifest illness.
The onset of prodromal symptoms shortly after exposure indicates:
a major radiation exposure to the whole body.
Some references refer to the prodromal stage as:
the NVD syndrome (Nausea, Vomiting, Diarrhea)
The latent period is also called:
The period of “well being.”
During the “latent period,” the exposed individual has no:
clinical symptoms or illness from the radiation exposure and appears to have recovered with no ill effects (not so…)
The latent period can extend from a few hours or less (at doses in excess of 50 Gy(t)) to:
weeks (at doses from 1 to 5 Gy(t)). Higher doses result in shorter latent periods.
Manifest illness is also referred to as:
The acute stage.
During the acute stage, what is evident?
the full clinical effects.
The acute stage is a dose related period characterized by what?
Three separate syndromes: Hematologic (hematopoetic) syndrome, Gastrointestinal Syndrome, and CNS Syndrome.
Hematopoietic syndrome occurs when humans receive whole body doses of ionizing radiation ranging from:
1 to 10 Gy(t) (100-1000 rad)
Gastrointestinal syndrome occurs when humans receive whole body doses of ionizing radiation ranging from:
6 to 10 Gy(t) (600-1000 rad)
CNS syndrome occurs when humans receive whole body doses of ionizing radiation of:
over 50 Gy(t) (over 5000 rad)
Prodromal stage of Hematopoietic syndrome starts at ____, lasts ____, and consists mainly of:
2 hours, 2 days, nausea and vomiting.
Describe the latent period of Hematopoietic syndrome:
follows the prodromal stage, can extend as long as 4 weeks and is characterized by a general feeling of wellness. There are no signs of illness, although the number of cells in the circulating blood are declining during this time. Stem cells die during the prodromal and latent periods.
Manifest illness of the hematopoietic syndrome is characterized by:
the reduction of all blood cell counts (pancytopenia). This results in anemia and hemorrhage (due to depression of RBC’s) and serious infections (due to depression of white cells-leukopenia.)
Hematopoietic syndrome: Manifest illness: at the lower limits of the dose range (which is_____), bone marrow cells will:
1 - 2 Gy(t) or 100 - 200 rad, repopulate the marrow to an extent great enough to support life in the majority of individuals.
Many people who suffer from the manifest illness of hematopoietic syndrome will recover how long after irradiation?
3 weeks to 6 months.
A few sensitive individuals may die how long after a whole body exposure to 200 rad? (2Gy(t))
6-8 weeks. As whole body dose increases from 2 to 10 Gy(t) irradiated individuals die sooner.
The primary cause of death in the hematopoietic syndrome is:
destruction of bone marrow, resulting in infection and hemorrhage.
Victims who received doses in excess of 5 Gy(t) at Chernobyl benefited from:
bone marrow transplants.
In humans, the gastrointestinal form of ARS appears at a threshold dose of about _____ and peaks after a dose of ____
6 Gy(t), 10 Gy(t)
Without medical support, persons receiving doses of 6 - 10 Gy(t) may die ______ days following exposure. Even with medical support, the exposed person will live only a few days longer.
3- 10
Prodromal stage of Gastrointestinal syndrome occurs within:
a few hours of post exposure.
Prodromal stage of gastrointestinal syndrome characterized by:
severe nausea and vomiting, which may be accompanied by severe cramps and diarrhea.
The latent period of the gastrointestinal syndrome can last as long as:
5 days.
The manifest illness stage of the gastrointestinal syndrome signs and symptoms
fever fatigue loss of appetite lethargy anemia leukopenia hemorrhage infection electrolyte imbalance emaciation
Death occurs from manifest illness stage of GI syndrome primarily because of:
damage to epithelial cells lining the GI tract.
Death of the exposed person due to epithelial damage to the GI tract during the manifest illness stage of ARS occurs within:
3-5 days of irradiation. Can also be caused by damage to bone marrow.
Gastrointestinal syndrome Manifest Illness stage: The _____ is most affected. The epithelial cells function as an essential barrier and their breakdown can cause:
small intestine. Infection (mostly from its own intestinal bacteria), dehydration and severe diarrhea.
CNS syndrome causes death within:
a few hours or 2-3 days after exposure.
Prodromal stage begins:
after irradiation.
Signs and symptoms of prodromal stage of CNS syndrome include:
excessive nervousness confusion severe nausea vomiting diarrhea loss of vision burning sensation of the skin loss of consciousness
Latent period of CNS syndrome may last up to:
12 hours.
Manifest illness of CNS syndrome signs and symptoms
Prodromal symptoms come back with increased severity and other symptoms appear.
CNS syndrome: Damaged blood vessels permit:
fluid to leak into the brain and cause increased fluid content creating intracranial pressure.
CNS syndrome: death caused by:
increased pressure in the confining cranial vault as a result of increased fluid content.
CNS syndrome: Manifest Illness: the bone marrow and the GI tract do not exhibit dramatic changes in the CNS syndrome because:
the individual does not live long enough. An increased survival time would result in the manifestation of dramatic changes in these systems.
ARS as a consequence of Chernobyl: Of the 444 people working at the power plant at the time of the explosion:
2 died instantly, 29 died within 3 months as a result of burns and severe injuries (Whole body doses of 6 Gy(t))
Japanese atomic bomb survivors are also examples of:
a human population affected by ARS.
LD 50/30:
Lethal Dose. Signifies the whole-body dose of radiation that can be lethal to 50% of the exposed population within 30 days.
LD 50/30 for adult humans is estimated to be:
3-4 Gy(t) or 300 - 400 rad without medical support.
Whole body doses greater than 6 Gy(t) may cause:
death to the entire population in 30 days w/o medical support.
With medical support, humans have tolerated doses as high as:
8.5 Gy(t)
Regardless of treatment, whole-body equivalent doses of greater than ____ are considered fatal
12 Gy(t)
When cells are exposed to sublethal doses of ionizing radiation , repair and recovery are:
possible. The surviving cells begin to repopulate permitting the functionally damaged organ to regain some/most of its functional ability.
Organs with oxygenated cells recover _____ than do hypoxic cells.
better
If both oxygenated and hypoxic cells receive a comparable dose of low-LET radiation:
Oxygenated cells are more severely damaged but those that survive repair themselves and recover from the injury. Hypoxic cells are less severely damaged, but do not repair and recover as efficiently.
Approximately __% of radiation-induced damage may be repaired over time. ____% is irreparable.
90, 10
_______ usually results after such a substantial partial-body exposure and leads to atrophy.
Substantial cell death
Atrophy may cause organs and tissues to:
lose their ability to function or they may recover.
Organ and tissue response to radiation exposure depends on:
radiosensitivity
reproductive characteristics
growth rate
Examples of tissues that suffer immediate consequences from high radiation doses:
skin
male and female reproductive organs
bone marrow
Effects on the skin: early radiologists and dentists developed:
radiodermititis
Radiodermititis is:
reddening of the skin caused by exposure to ionizing radiation. EVentually lead to cancerous lesions on hands and fingers.
William Herbert Rollins:
Boston dentist who suffered severe burns on hands and fingers. Known as first advocate of radiation protection.
Three layers of the skin are:
epidermis, dermis, and hypodermis. (outer to inner layers)
all layers of skin and accessory structures are involved in response of tissue to:
radiation exposure.
A single absorbed dose of ____ can cause kin erythema within 24 to 48 hours after irradiation.
2 Gy(t)
Desquamation:
shedding of outer layer of skin.
High radiation doses can cause this effect on the skin:
Desquamation.
Epilation or alopecia:
hair loss
ring worm was once treated (and cured) by irradiation of the affected area with:
grenz rays (10 - 20 kvp) If ringworm was located on scalp, hair would fall out for a period of time.
High level fluoro used during cardiovascular or therapeutic interventional procedures can result in:
radiation induced skin injuries.
Doses as low as ____ are capable of depressing male sperm population and also has potential to cause genetic mutation in future generations.
.1 Gy
A gonadal dose of ___ may delay or suppress menstruation in the female.
.1 Gy
Males: stem cells of testes are spermatogonia and ________ reproduce.
constantly
It takes __ - __ weeks for male stem cell to develop into functionally mature germ cell.
3 - 5
Ovarian stem cell is the:
oogonia
Oogonia multiply to millions of cells during:
fetal development and then decline throughout life.
Mature ova cells range in size from small to large. intermediate size follicles are _____ radiosensitive, small follicles are _____ radiosensitive, and large follicles are _____ radiosensitive
most, least, moderately
A radiation dose of ____ may lead to temporary sterility for up to 12 months in males.
2 Gy(t)
A radiation dose of ___ maybe lead to permanent sterility in males.
5-6 Gy(t)
Ovaries are very radiosensitive when?
during fetal stage and easy childhood. If ovaries are irradiated during this period of time, germ cell death occurs because of ovarian atrophy.
A dose of ___ to gonads may delay or supress menstruation.
.1 Gy(t)
Radiosensitivity of ovaries declines between ages:
20 & 30.
A single radiation exposure of ___ to ovaries usually results in temporary sterility in females.
2 Gy(t)
A dose of ____ will result in permanent sterility in females.
5-6 Gy(t)
Genetic mutations are also a consequence of:
gonadal irradiation.
Genetic mutations have been produced in experimental animals when their ovaries were irradiated with dose as low as ____
.25 Gy(t)
During the 1920’s and 30’s, periodic ________ were used as a means for monitoring imaging personnel.
blood counts
A whole body radiation dose of ____ would produce a measurable hematologic depression.
.25 Gy(t)
Cells of the hematopoietic system all develop from a single precursor cell:
Pluripotential stem cell
Cells of the hematopoietic system include:
Lymphocytes, granulocytes, thrombocytes and erythrocytes.
Lymphocytes:
WBC’s that play active role in producing immunity for the body.
Granulocytes
WBCs that act as scavengers to fight bacteria
Thrombocytes:
platelets, blood cells that initiate blood clotting and prevent hemorrhage.
Erythrocytes:
RBCs that through their hemoglobin carry oxygen from the lungs to all body tissue and cells as blood circulates.
Life span of Lymphocytes:
a few hours
life span of erythrocytes
almost 120 days.
Most pronounced effect 0of radiation on hematologic system is:
a reduction in the number of blood cells in the peripheral circulation.
Highly specialized, non dividing cells in circulating flood with the exception of lymphocytes are relatively:
radioINsensitive.
True or false: Lymphocytes are not radiosensitive
False. Lymphocytes are very radiosensitive.
A radiation dose of ____ will cause a decrease in neutrophils.
.5 Gy(t)
A radiation dose greater than ____ can cause a decrease in the number of thrombocytes.
.5 Gy(t)
A measurable hematologic depression can be cause by a whole-body dose of radiation as low as ____
.25 Gy(t)
Depletion of cells that protect the body against disease results in:
the body losing its ability to fight infection.
Cytogenetics:
Study of cell genetics with emphasis on cell chromosomes
Karyotype:
Cytogenetic analysis of chromosomes throughout he use of a chromosome map.
Chromosome damage caused by radiation can be evaluated during:
metaphase.
