Chapter 8: Early Tissue Reactions and Their Effects on Organ Systems Flashcards
Biologic effects of radiation that occur relatively soon after humans receive high doses of ionizing radiation (alpha, beta)
Early Effects
Not common in diagnostic imaging
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
Produced by a substantial dose of ionizing radiation
Early Effects
Biologic effects of radiation that occur relatively soon after humans receive high doses of ionizing radiation
Substantial evidence of the consequences of such effects comes from numerous laboratory animal studies and data from observation of some irradiated human populations
Not common in diagnostic imaging
Produced by a substantial dose of ionizing radiation
Early Effects
The term somatic originates from the Greek term “soma” meaning
body
are effects upon the body that was irradiated
somatic effects
are effects upon future generations
Genetic 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
Vary depending on the duration of time after exposure to ionizing radiation
Early Tissue Reactions
a point at which they begin to appear and below which they are absent
These results have a threshold,
As the radiation dose increase
the severity of these effects also increase
The amount of biologic damage depends on the
actual absorbed dose of ionizing radiation
Vary depending on the duration of time after exposure to ionizing radiation
As the radiation dose increases, the severity of these effects also increases.
These results have a threshold, a point at which they begin to appear and below which they are absent.
The amount of biologic damage depends on the actual absorbed dose of ionizing radiation.
Early Tissue Reactions
If the consequences include cell killing and are directly related to the dose received, they are
somatic tissue reactions
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
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 or False
True
Early Tissue Reactions
Early tissue reactions are caused by
cell death
High-dose effects include:
- Nausea
- Fatigue
- Erythema (diffuse redness over an area of skin after irradiation)
- Epilation (loss of hair)
- Blood disorders
- Intestinal disorders
- Fever
- Dry and moist desquamation (shedding of the outer layer of skin)
- Depressed sperm count in the male
- Temporary or permanent sterility in the male and female
- Injury to the central nervous system (at extremely high radiation doses)
diffuse redness over an area of skin after irradiation
Erythema
loss of hair
Epilation
shedding of the outer layer of skin
Dry and moist desquamation
at extremely high radiation doses
Injury to the central nervous system
Whole-body dose of 6 Gyt can result in
many of these manifestations or organic damage occurring in succession (acute radiation syndrome).
The various types of organic damage may be related to
the cellular effects
intestinal disorders are caused by damage to the sensitive epithelial tissue
lining the intestines
- 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)
.Whole-body dose of 6 Gyt can result in many of these manifestations or organic damage occurring in succession (acute radiation syndrome)
Early Tissue Reactions
Radiation sickness
Acute radiation syndrome (ARS)
Occurs in humans after whole-body reception of large doses of ionizing radiation delivered over a short period of time (from several hours to a few days).
Acute radiation syndrome (ARS)
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 therapy
is the medical term that defines a collection of symptoms
Syndrome
is a collection of symptoms associated with high-level radiation exposure
Acute radiation syndrome (ARS)
Three separate dose-related syndromes occur as part of the total-body syndrome
Acute radiation syndrome (ARS)
Three separate dose-related syndromes or conditions occur as part of the acute radiation syndrome:
- Hematopoietic syndrome
- Gastrointestinal syndrome
- Cerebrovascular syndrome
known as “bone marrow syndrome,”
- most radiation sensitive out of the 3
Hematopoietic syndrome
occurs when people receive whole-body doses of ionizing radiation ranging from 1 to 10 Gyt
Hematopoietic syndrome
manufactures the corpuscular elements of the blood and is the most radiosensitive vital organ system in humans
The hematopoietic system
Radiation exposure causes the number of red blood cells, white blood cells, and platelets in the circulating blood to decrease
Hematopoietic syndrome
Dose levels that produce this syndrome may also damage cells in other organ systems and cause the affected organ or organ system to fail
Hematopoietic syndrome
For persons with hematopoietic syndrome, survival time shortens as the
radiation dose increases
Because bone marrow cells are being destroyed, the body becomes more susceptible to infection (mostly from its intestinal bacteria) and more prone to hemorrhage
hematopoietic syndrome
because of excessive bone marrow destruction causing anemia and little or no resistance to severe infection.
death occurs
Death may occur 6 to 8 weeks after irradiation in some susceptible human subjects who receive a whole-body dose just exceeding
2 Gyt
as the whole-body dose increases from 2 to 10 Gyt, all irradiated individuals will die and in a
shorter period
If the radiation exposure is, however, in the range of 1 to 2 Gyt, bone marrow cells will eventually
repopulate to a level adequate to support life in most individuals. Many of these people recover from 3 weeks to 6 months after irradiation.
Survival probability of patients with hematopoietic syndrome is enhanced by
intense supportive care and special hematologic procedures
benefited from bone marrow transplants is not an absolute cure for patients with because many individuals undergoing bone marrow transplant die of burns or other radiation-induced damage they sustained before the transplanted stem cells have had a chance to support recovery.
hematopoietic syndrome
*From 1 to 10 Gyt
*Damage to the body
*Outcome
- once you get to 5 and 10 GYt with no medical attention you have death
- bone marrow transplant are not always a cure but does help
Hematopoietic syndrome (bone marrow syndrome)
The irradiated person’s general state of health at the time of irradiation strongly influences the possibility of
recovery
appears at a threshold dose of approximately 6 Gyt and peaks after a dose of 10 Gyt.
Gastrointestinal syndrome.
Without medical support to sustain life, exposed persons receiving doses of 6 to 10 Gyt may die if not medically treated within how many days
3 to 10 days after being exposed.
Even if medical assistance is provided, the exposed person will live only a few days longer. Survival time does not change with dose in this syndrome.
Gastrointestinal syndrome
minutes, hours, days and couple weeks
Early Tissue reactions
considered days, week, and minutes what kind of somatic effect
early somatic effects
considered months, years what kind of somatic effects?
late somatic effects
- no tolerance to radiation
- going to have biological damage
Threshold or Non threshold
Non threshold
Up to a certain point radiation is okay until it reaches a certain number / point then you are going to start seeing biological damage
Threshold or Non threshold
Threshold
repeated radiation injuries is considered a
cumulative dose
is the medical term that defines a collection of symptoms
Syndrome
Severe nausea, vomiting, and diarrhea persist for as long as 24 hours
Gastrointestinal syndrome
beginning, stage occurs called
prodromal
may last for several days. During this time, the outward symptoms disappear
latent period
most sensitive part of your GI tract
small intestine
signs of gastrointestinal syndrome:
- Severe nausea
- Vomiting
- Diarrhea
- Fever (as in hematopoietic syndrome)
- Fatigue
- Loss of appetite
- Lethargy
- Anemia
- Leukopenia (decrease in the number of white blood cells)
- Hemorrhage (GI tract bleeding because the body loses its blood-clotting ability)
- Infection
- Electrolyte imbalance
- Emaciation
decrease in the number of white blood cells
Leukopenia
GI tract bleeding because the body loses its blood-clotting ability
Hemorrhage
Fatality occurs primarily as a result of catastrophic damage to the epithelial cells that line the GI tract. This results in the death of the exposed person within 3 to 5 days from a combination of infection, fluid loss, and electrolytic imbalance
Gastrointestinal syndrome
Because epithelial cells function as an essential biologic barrier, their breakdown leaves the body vulnerable to:
- Infection (mostly from its intestinal bacteria)
- Dehydration
- Severe diarrhea
Some epithelial cells regenerate in the period before death occurs. However, because of the large number of epithelial cells damaged by the radiation, death may occur before sufficient cell regeneration is accomplished. The workers and firefighters at Chernobyl who did not survive are examples of humans who died as a result of GI syndrome.
Gastrointestinal syndrome
receive doses of 50 Gyt or more of ionizing radiation.
Cerebrovascular syndrome
A dose of this magnitude can cause death within a few hours to 2 or 3 days after exposure.
- severe damage to the body
Cerebrovascular syndrome
Signs and symptoms of Cerebrovascular syndrome:
- Excessive nervousness
- Confusion
- Severe nausea
- Vomiting
- Diarrhea
- Loss of vision
- Burning sensation of the skin
- Loss of consciousness
- Disorientation and shock
- Periods of agitation alternating with stupor
- Ataxia (confusion and lack of muscular coordination)
- Edema in the cranial vault
- Loss of equilibrium
- Fatigue
- Lethargy
- Convulsive seizures
- Electrolytic imbalance
- Meningitis
- Prostration
- Respiratory distress
- Vasculitis
- Coma
beginning stage
- dose of 1 Gyt
- Nausea, vomiting, diarrhea, fatigue, leukopenia (white blood cells are depleting)
- whole body dose of 1 GYt or more
Prodromal stage
white blood cells are depleting
leukopenia
Your hidden symptoms you can’t really see what’s going to be happening yet
- dose 1 to 100 Gyt
- no visible signs
- this is where your body is going to recover or continue on having different effects
Latent stage
Hematopoietic, gastrointestinal, and cerebrovascular fall under something called what which refers to what you are able to see.
- signs and symptoms come visible
manifest
the lower the dose
the less severe the symptoms
the higher the dose
the more severe the symptoms
dose of 1 to 10 Gyt
- 6–8 wk (doses over 2 Gyt)
- Nausea; vomiting; diarrhea; decrease in number of red blood cells, white blood cells, and platelets in the circulating blood; hemorrhage; infection
Hematopoietic
average survival time of gastrointestinal stage
3-10 days
dose of 6 to 10 Gyt
- 3–10 days survival time
- Severe nausea, vomiting, diarrhea, fever, fatigue, loss of appetite, lethargy, anemia, leukopenia, hemorrhage, infection, electrolytic imbalance, and emaciation
Gastrointestinal
dose of 50 Gyt and above
- Several hours to 2–3 days survival time
- 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
Cerebrovascular
last stage of acute radiation lethality
- the recovery is the 3 month mark there can be permanent damage
- are they able to recover or is there going to be death
recovery
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 ( 3 types)
Recovery or death
The massive explosion that blew apart the unit 4 reactor at the nuclear power station in Chernobyl in the Soviet Union on April 26, 1986, provides an example of humans developing ARS. During the explosion, several tons of burning graphite, uranium dioxide fuel, and other contaminants such as cesium-137, iodine-131, and plutonium-239 were ejected upward into the atmosphere in a 3-mile-high radioactive plume of intense heat. Of 444 people working at the power plant at the time of the explosion, two died instantly, and 29 died within 3 months of the accident as a consequence of thermal trauma and severe injuries caused by whole-body doses of ionizing radiation of approximately 6 Gyt or more.1–3
- Without useful physical monitoring devices, biologic criteria such as the occurrence of nausea and excessive vomiting played an essential role in the identification of radiation casualties during the first 2 days after the nuclear disaster. ARS caused the hospitalization of at least 203 people.3,4 Determining the lapse of time from the exposure of the victims to the onset of nausea and vomiting completed the biologic criteria. Dose assessment was determined from serial measurements of levels of lymphocytes and granulocytes in the blood and quantitative analysis of the frequency of dicentric chromosomes (altered chromosomes with two centromeres) present in blood and hematopoietic cells, originating from bone marrow. The data were compared with doses and effects from earlier radiation mishaps.2,3
Acute radiation syndrome as a consequence of the Chernobyl nuclear power plant accident
An analysis in which damage to tissues is used to estimate radiation dose is referred to as
biologic dosimetry
The Japanese atomic bomb survivors of Hiroshima and Nagasaki are examples of a human population affected by ARS as a consequence of war. Follow-up studies of the survivors, who did not rapidly die of this syndrome, demonstrated late tissue reactions (e.g., cataracts) and stochastic effects of ionizing radiation, such as induction of leukemia. The atomic bombing of Japan and the nuclear accident at Chernobyl caused the medical community to recognize the need for a thorough understanding of ARS and the appropriate medical support of persons affected.
Acute radiation syndrome as a consequence of the atomic bombing of Hiroshima and Nagasaki
The % of the population in # how many days
Lethal dose (LD)
the LD 50/30 for adult humans is estimated to be
3.0 to 4.0 Gyt without medical support
lethal dose for people without being medicated
LD 50/30
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
another name for non linear
sigmoid
lethal dose for humans when medicated most accurate
LD 50/60 may be more accurate for humans
when there is more oxygen is it easier or harder to repair
easier
Since cells contain a repair mechanism inherent in their biochemistry (repair enzymes), repair and recovery can occur when cells are exposed to sub-lethal doses of ionizing radiation
- After this level of irradiation, surviving cells will be able to divide and thereby begin to repopulate in the irradiated region.
- 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
In the repair of sublethal damage, oxygenated cells, which as a result, receive more nutrients, allow for a better prospect for recovery than do hypoxic, or poorly oxygenated, cells that consequently receive fewer nutrients.
- When both cell categories are exposed to a comparable dose of low-LET radiation, the oxygenated cells are more severely damaged, but those that survive can repair themselves and recover from the injury. Even though they are less severely damaged, the hypoxic cells do not repair and recover as efficiently.
repair and recovery
repeated radiation injuries have
cumulative effect
how much radiation induced damage will be irreparable
10%
how much radiation induced damage will be repaired over time
remaining 90%
A destructive response in biologic tissue is likely to occur when any part of the human body receives a high radiation dose. Significant cell death usually results, leading to the shrinkage of organs and tissues, a process referred to as atrophy.
local tissue damage
consequence to atrophy
Organatrophys and tissues sustaining such damage may lose their ability to function, or they may recover
shrinkage of organs and tissue
atrophy
If recovery does occur, it may be partial or complete, depending on the types of cells involved and the dose of radiation received. Should this not happen, then necrosis, or death, of the irradiated biologic structure results.
local tissue damage
organ and tissue response to radiation exposure depends on :
-radiosensitivity
-reproductive characteristics
-growth rate
Some local tissues suffer immediate consequences from high radiation doses. Examples of such tissues include the following:
- Skin
- Male and female reproductive organs
- Bone marrow
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
2Gyt
true or false
skin constantly regenerating
true
1st layer of defense protecting yourself
the skin
exposed skin immune to
infections
a significant reddening of the skin caused by excessive exposure to relatively low-energy ionizing radiation that eventually led to cancerous lesions on the hands and fingers
radiodermatitis
In 1898 after personally suffering severe burns, which he ultimately attributed to accumulated radiation exposures.
- a Boston dentist, began investigating the potential hazards of radiation exposure. His experimentation led to him becoming the first known determined advocate for radiation protection.
- performed experiments on guinea pigs that led to “three important safety practices for radiographers: wear radiopaque glasses; enclose the x-ray tube in protective housing; and irradiate only areas of interest on the patient, covering adjacent areas with radiopaque materials.
William Herbert Rollins
Because the skin functions as an ongoing regenerative protection system, it is relatively
radiosensitive
Approximately of the body’s surface skin cells are replaced daily by stem cells from an underlying basal layer
2%
shedding of the outer layer of skin, occurs at higher radiation doses. generally manifests first as moist skin peeling, and then a dry skin flaking may develop
- 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
Historically, skin diseases, such as ringworm, were treated and successfully cured by irradiating the affected area with
grenz rays (x-rays in the energy range of 10 to 20 kVp)
Human germ cells are relatively
radiosensitive
Doses as low as can depress the male sperm population, and this same dose has the potential to cause genetic mutations in future generations
0.1 Gyt
In females, a gonadal dose of may delay or suppress menstruation
0.1 Gyt
stem and germ cells are sensitive because they are
immature
who keep reproducing sperm
Males
are more sensitive because they are born with the amount of eggs that they have and that’s it
females
with females as you get older
you become more sensitive
Gonadal dose of ionizing radiation that will cause temporary sterility in the male and in the female
2 to 3 Gyt with medical attention
Gonadal dose of ionizing radiation that will cause permanent sterility in the male and in the female
about 5 to 6 Gyt
the ovarian stem cells they multiple into millions of cells only through
fetal development
Animal experiments and data from irradiated human populations have provided important information on gonadal response to radiation exposure. Irradiated human populations include:
- Patients who have undergone radiation therapy
- Radiation accident victims
- Volunteer convicts
male germ cells from most sensitive (least resistant, most immature, radiosensitive) to least sensitive (most mature, least sensitive, most resistant, radioresistant)
- spermatogenia
- spermatocyte
- spermatid
- sperm
female germ cells from most sensitive ( most immature, least resistant) to least sensitive ( most mature, radioresistant)
- primordial follicle
- mature follicle
- corpus luteum
- ovum
In the female, the oogonia, the ovarian stem cells, multiply to millions of cells only during fetal development, before birth, and then they steadily decline in number throughout life
true or false
true
As a brief review, recall that during the 1920s and 1930s, periodic blood counts were the only means of radiation exposure monitoring for radiation workers engaged in radiologic practices.
true or false
true
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
what dose do you see start seeing changes in your blood
0.25 gyt
When blood counts were used to monitor the effects of radiation exposure among those who worked with radiation, a whole-body radiation dose of would be required to produce a measurable hematologic depression
- Such a dose could cause enough of a decrease in the number of lymphocytes in the blood to render the body vulnerable to infection by foreign invaders.
0.25 Gyt
The hematopoietic system consists of:
- Bone marrow
- Circulating blood
- Lymphoid organs (lymph nodes, spleen, and thymus gland)
Consists of bone marrow, circulating blood, and lymphoid organs (lymph nodes, spleen, and thymus gland)
Hematopoietic System
Cells of this system develop from a single precursor cell, the pluripotential stem cell
Hematopoietic System
Radiosensitivity of lymphocytes, neutrophils, granulocytes, thrombocytes (platelets), and erythrocytes
hematopoetic system
Most of these blood cells are manufactured in
bone marrow
The human body may experience health-related consequences throughout life if there is a decrease in the numbers of these various cells. Some of these consequences will be increased susceptibility to aggressive infectious organisms, higher risk of hemorrhage, and anemia.
Hematopoietic system
are the most immature and sensitive to radiation
stem cells
defined as the study of cell genetics with an emphasis on cell chromosomes
cytogenetics
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,
karyotype
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
most sensitive stage of mitosis
metaphase
most chromosome damage result from your
indirect free radical
