Chapter 8 Flashcards
Biologic effects of radiation that occur relatively soon after humans receive high doses of ionizing radiation
Early Effects
Not common in diagnostic imaging
Produced by a substantial dose of ionizing radiation
Early Effects
Substantial evidence of the consequences of such effects comes from numerous laboratory animal studies and data from observation of some irradiated human populations
early effects
are effects upon the body that was irradiated
somatic effects
are effects upon future generations because of irradiation of germ cells in previous generations
genetic effects
Biologic damage sustained by living organisms (such as humans) as a consequence of exposure to ionizing radiation
somatic effects
Depending upon the length of time from the moment of irradiation to the first appearance of symptoms of radiation damage, the effects are classified as either
Early somatic effects
Late somatic effects
-minutes
-hours
-days
-couple weeks
early effects
-high dose of ionizing radiation
-not common
-substantial dose
early effects
when the radiation dose is increased what happens to the biologic damage
increased biologic damage
a point at which they begin to appear and below which they are absent
threshold
Vary depending on the duration of time after exposure to ionizing radiation
Early Tissue Reactions
what does the amount of biologic damage depend on ?
The amount of biologic damage depends on the actual absorbed dose of ionizing radiatio
no tolerance
nonthreshold
tolerate up to a certain point
threshold
Appear within minutes, hours, days, or weeks of the time of radiation exposure
early tissue reactions
Requires a substantial dose of ionizing radiation to produce these biologic changes soon after irradiation
early tissue reactions
true or false
With the exception of certain lengthy high-dose-rate procedures, diagnostic imaging examinations do not usually impose radiation doses sufficient to cause early tissue reactions
true
list some high dose effects of early tissue reactions
High-dose effects include nausea, fatigue, erythema, epilation, blood disorders, intestinal disorders, fever, dry and moist desquamation, depressed sperm count in the male, temporary or permanent sterility in the male and female, and injury to the central nervous system (at extremely high radiation doses)
can result in many of these manifestations or organic damage occurring in succession (acute radiation syndrome)
Whole-body dose of 6 Gyt
Radiation sickness
ARS
Occurs in humans after whole-body reception of large doses of ionizing radiation delivered over a short period of time
ars
what does ars stand for
acute radiation syndrome
Data from epidemiologic studies of human populations exposed to doses of ionizing radiation sufficient to cause ARS have been obtained from
Atomic bomb survivors of Hiroshima and Nagasaki
Marshall Islanders who were inadvertently subjected to high levels of fallout during an atomic bomb test in 1954
Nuclear radiation accident victims such as those injured in the 1986 Chernobyl disaster
Patients who have undergone radiation therap
is a collection of symptoms associated with high-level radiation exposure
ARS
how many separate dose related syndromes occur as part of the total body syndrome
three separate dose-related syndromes occur as part of the total-body syndrome
Symptoms of ARS
-Hematopoietic syndrome (bone marrow syndrome)
-gastrointestinal syndrome
-cerebrovascular syndrome
most radiation sensitive out of the three symptoms of ARS
Hematopoietic syndrome (bone marrow syndrome
-from 1 to 10 Gy
-damage to the body
(1-2 gry recover in a couple weeks or months)
(5-6 gry w/o med = death)
Hematopoietic syndrome (bone marrow syndrome
*Appears at a threshold dose of approximately 6 Gyt and peaks after a dose of 10 Gyt
*Damage to the body
Gastrointestinal syndrome
*Results from doses of 50 Gyt or more *Damage to the body
Cerebrovascular syndrome
signs of gastrointestinal syndrome:
Severe nausea, vomiting, diarrhea, fever, fatigue, loss of appetite, lethargy, anemia, leukopenia, hemorrhage, infection, electrolytic imbalance, and emaciation
symptoms of cerebrovascular syndrome
Same as hematopoietic and gastrointestinal, plus excessive nervousness, confusion, lack of coordination, loss of vision, burning sensation of the skin, loss of consciousness, disorientation, shock, periods of agitation alternating with stupor, edema, loss of equilibrium, meningitis, prostration, respiratory distress, vasculitis, coma
symptoms of prodomal
Nausea, vomiting, diarrhea, fatigue, leukopenia
average survival time of Hematopoietic
6–8 wk (doses over 2 Gyt)
symptoms of Hematopoietic
Nausea; vomiting; diarrhea; decrease in number of red blood cells, white blood cells, and platelets in the circulating blood; hemorrhage; infection
symptoms of latent phase
none
average survival time of gastrointestinal stage
3-10 days
average survival time of cerebrovascular
several hours to 2-3 days
what is the most sensitive in the gi tract
small intestine
what are the stages of acute radiation lethality
-prodromal (first stage)
-latent (second stage)
-hematopoietic (manifest)
-gastrointestinal (manifest)
-cerebrovascular (manifest)
-recovery
ARS presents in four major response stages:
Prodromal, or initial, stage
Latent period
Manifest illness
Recovery or death
lethal dose for people without being medicated
LD 50/30
what is the estimated dose for humans
For adult humans the estimated dose is 3.0 to 4.0 Gy
LD 50/30
Signifies the whole-body dose of radiation that can be lethal to 50% of the exposed population within 30 days
Lethal dose
Location of nuclear power plant
Date of accidentDescription of events
Use of biologic criteria in the identification of radiation casualties during the first 2 days after the accident
Impact of accident on workers, firefighters, and local residents
Doses of ionizing radiation received
Dose assessment as determined from biologic dosimetry
ARS and the Chernobyl Nuclear Power Plant Accident
Human population affected by ARS as a consequence of war
Follow-up studies of survivors who did not die of ARS demonstrated late tissue reactions and stochastic effects of ionizing radiation.
Created an awareness of the need for a thorough understanding of ARS and appropriate medical support of persons affected
ARS as a Consequence of the Atomic Bombing of Hiroshima and Nagasak
another name for non linear
sigmoid
lethal dose for humans when medicated
LD 50/60 may be more accurate for humans
when there is more oxygen is it easier or harder to repair
easier
Because cells contain a repair mechanism inherent in their biochemistry (repair enzymes), repair and recover can occur when cells are exposed to sublethal doses of ionizing radiation.
After this level of irradiation, surviving cells will be able to divide and thereby begin to repopulate in the irradiated organ.
This process permits an organ that has sustained functional damage as a result of radiation exposure to regain some or most of its useful ability
repair and recovery
how much radiation induced damage will be irreparable
10 percent
how much radiation induced damage will be repaired over time
remaining 90 percent
what type effect does repeated injuries have
culmultive effect
In the repair of sublethal damage, cells that are oxygenated, which as a result receive more nutrients, have a better prospect for recovery than do hypoxic, or poorly oxygenated, cells that consequently receive fewer nutrients.
repair and recovery
consequence to atrophy
Organs and tissues sustaining such damage may lose their ability to function, or they may recover
A destructive response in biologic tissue can occur when any part of the human body receives a high radiation dose.
Significant cell death usually results after such a substantial partial-body exposure. This leads to atrophy of organs and tissues.
local tissue damage
If recovery occurs, it may be partial or complete, depending on the type of cells involved and the dose of radiation received.
If organ and tissue recovery fails to occur, necrosis, or death, of the irradiated biologic structure results
local tissue death
organ and tissue response to radiation exposure depends on :
-radiosensitivity
-reproductive characteristics
-growth rate
three layers of the skin
-epidermis (outer layer)
-dermis (middle layer)
-hypodermis (subcutaneous layer)
accessory structures of the skin include:
-hair follicles
-sensory receptors
-sebaceous glands
-sweat glands
what dose will cause erythema with in 24 to 48 hours
2Gy
true or false
skin constantly regenerating
true
medical term for peeling skin, which occurs when the body sheds dead skin cells from the epidermis, the outermost layer of skin
Desquamation
skin condition that occurs when someone is exposed to ionizing radiation
radiodermatitis
epilation or loss of hair
alopecia
-moderate doses of radiation may result in temporary hair loss
-large doses of radiation may result in permanent hair loss
alopecia
Epilation or loss of hair (alopecia)
Moderate doses of radiation may result in temporary hair loss.
Large doses of radiation may result in permanent hair loss.
Historical evidence of treating skin diseases such as ringworm
Grenz rays
Oncology patients receiving orthovoltage radiation therapy treatment have demonstrated significant evidence of skin damage.
Cardiovascular or therapeutic interventional procedures that use high-level fluoroscopy for extended periods of time can cause significant effects on the ski
effects on the skin
Gonadal dose that can depress the male sperm population or cause a genetic mutation in future generations
Gonadal dose that may delay or suppress menstruation in the female
Radiosensitivity of human germ cell
Gonadal dose of ionizing radiation that will cause temporary sterility in the male and in the female
Gonadal dose of ionizing radiation that will cause permanent sterility in the male and in the femal
effects on the reproductive system
true or false
females more sensitive than males
true
true or false
as you get older, even more sensitive your reproductive organs are
true
what is temp sterility
3
permanent sterility is
5
male germ cels from most sensitive to least sensitive
spermatogenia
spermatocyte
spermatid
sperm
female germ cells from most sensitive to least sensitive
primordial follicle
mature follicle
corpus luteum
ovum
true or false
During the 1920s and 1930s, periodic blood counts were the only means of monitoring workers engaged in radiologic practices
true
what dose do you see start seeing changes in your blood
0.25
made the practice of requiring periodic blood counts for monitoring radiation damage obsolete.
Use of personnel dosimeters for monitoring of occupational exposure
Radiation protection programs have long since abandoned relying on
hematologic depression as a means for monitoring imaging personnel to assess whether they have sustained any degree of radiation damage from occupational exposure
Consists of bone marrow, circulating blood, and lymphoid organs (lymph nodes, spleen, and thymus gland)
Hematopoietic System
Cells of this system all develop from a single precursor cell, the pluripotential stem cell
Hematopoietic System
is the study of cell genetics with emphasis on cell chromosomes
Cytogenetics
A cytogenetic analysis of chromosomes may be accomplished through the use of a chromosome map called
a karyotype. This map consists of a photograph or photomicrograph
is the phase of cell division in which chromosome damage caused by radiation exposure can be evaluated. Chromosome aberrations and chromatid aberrations have been observed at metaphase
Metaphase
Radiosensitivity of lymphocytes, neutrophils, granulocytes, thrombocytes (platelets), and erythrocytes
Hematopoietic System
