UNIT 3: Early Tissue Reactions Flashcards
List the events/populations that provide evidence of early effects: Whole body doses
-Atomic Bomb Survivors
-Marshall islanders who were inadvertently subjected to high level of fallout during an Atomic bomb test in 1974
-Nuclear radiation accident victims, such as those injured in the 1986 chernobyl disaster
-Patients who have undergone radiation therapy
List the events/populations that provide evidence of early effects: Local tissue damage
An enourmous amount of radiation from high level fluoro cases and multiphase CT will cause those early effects
Genetic effects
effects upon future generations due to the irradiation of germ cells in previous generations
Somatic effects
divided into early and late effects
Threshold dose
● effect is only seen after dose is received to the tissues or whole body
● most early effects follow this mode
● local tissue effects such as skin, hair follicles, cataracts
● ARS
Non-Threshold Dose
any dose may cause the effect seen with some late effects
What is the dose/response graph?
A generalized graph for all early tissue effects
Label the dose/response graph (curve) of early tissue reactions: A, B, C
A. Severity of biological effect
B. Absorbed dose of ionizing radiation
C. Response to increasing absorbed dose
What are the 3 syndromes of ARS?
Hematopoietic, Gastrointestinal, Cerebrovascular
Hematopoietic Symptoms and Threshold
-Nausea; vomiting; diarrhea; decrease in number of red blood cells, white blood cells, and platelets in the circulating blood; hemorrhage; infection
- 1–10 Gy
Gastrointestinal Symptoms and Threshold
-Severe nausea, vomiting, diarrhea, fever, fatigue, loss of appetite, lethargy, anemia, leukopenia, hemorrhage, infection, electrolytic imbalance, and emaciation
- 6–10 Gy
Cerebrovascular Symptoms and Threshold
-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
- 50 Gy and above
List and define the 4 stages of ARS:
- Prodromal- initial signs and symptoms: Nausea, vomiting and diarrhea
- Latent period- symptoms fade
- Manifest illness – symptoms return with more intensity
- Recovery or death- exposed recovers or dies
Define LD’s
the % of deaths in a irradiated population/days
What does LD 50/30 mean?
Often used to express the lethality of radiation doses on experimental animals. 50% of animals will die in 30 days.
What does LD 50/60 mean?
Often used to express the lethality of radiation doses on humans. 50% of humans will die in 60 days.
List the LD 50/30 for adults without medical support
LD 50/30 for adult humans is estimated to be 3.0 to 4.0 Gyt without medical support
3 layers of the skin
-Epidermis, or outer, layer
-Dermis, or middle, layer composed of connective tissue
-Hypodermis, a subcutaneous layer of fat and connective tissue
What are the local skin effects?
Erythema, Moist and Dry Desquamations, Epilation (hair loss)
Erythema and its threshold dose
Redening of skin. A single absorbed dose of 2 Gyt can cause radiation-induced skin erythema within 24 to 48 hours after irradiation
Moist and dry Desquamation and its threshold dose
Shedding of the outer layer of skin, occurs at higher radiation doses. Desquamation generally manifests first as moist skin peeling, and then a dry skin flaking may develop. 18 Gy.
Epilation Symptoms and Threshold dose
Hair loss (also called alopecia), can be caused by exposure to radiation since hair follicles are growing tissue. Moderate doses of radiation generally produce temporary hair loss, whereas large radiation doses can result in permanent hair loss.
Temporary: 3Gyt
Permanent: 7 Gyt
Who is at risk for local skin effects during high dose fluoroscopy?
- Larger patients: Less possible SOD, Automatic Brightness Stabilization
- Drugs: Actinomycin D & Adriamycin
- Patients with Ataxia, Telangiectasia, Diabetes or Collagen vascular disease
- Previous fluoroscopic guided procedures
Early effects on reproductive systems and doses: Male and Female
-Males: Doses as low as 0.1 Gy can depress the male sperm population, and this same dose has the potential to cause genetic mutations in future generations
-Females: a gonadal dose of 0.1 Gy may delay or suppress menstruation
The hematopoietic system consists of:
Bone marrow, Circulating blood, Lymphoid organs (lymph nodes, spleen, and thymus gland)
Hematologic Effects
a whole-body radiation dose of 0.25 Gy would be required to produce a measurable hematologic depression. Such a dose could cause enough of a decrease in the number of lymphocyte in the blood to render the body vulnerable to infection by foreign invaders.
Cytogenetic effects
May be defined as the study of cell genetics with an emphasis on cell chromosomes. Metaphase is the phase of cell division in which chromosome damage caused by radiation exposure can be evaluated. Chromosome aberrations (deviation from normal development or growth of structures that contain genetic material) and chromatid aberrations have been observed at metaphase. Difficult to see at <100mGy. Multi-hit aberrations are more concerning for late effects. No known threshold.
List the possible effects after bone marrow and circulating blood receives a significant (cell killing) dose: Lymphocytes
The lymphocytes and the spermatogonia are the most radiosensitive cells in the body. Lymphocytes are reduced in number within minutes or hours after exposure, and they are very slow to recover.
List the possible effects after bone marrow and circulating blood receives a significant (cell killing) dose: Granulocytes
Granulocytes experience a rapid rise in number (granulocytosis) followed first by a rapid decrease and then a slower decrease in number (granulocytopenia).
List the possible effects after bone marrow and circulating blood receives a significant (cell killing) dose: Thrombocytes
The depletion of platelets (thrombocytopenia) after irradiation develops more slowly, again because of the longer time required for the more sensitive precursor cells to reach maturity.
List the possible effects after bone marrow and circulating blood receives a significant (cell killing) dose: Erythrocytes
Less sensitive than the other blood cells because of their very long lifetime in the peripheral blood.
Vocab: Acute Radiation Syndrome (ARS)
When a very high dose of radiation is received around the whole body, many early effects can occur at once. Also called radiation sickness.
Vocab: Desquamation
shedding of the outer layer of the skin
Vocab: Early Tissue Reactions
tissue reactions that occur within hours or days of exposure.
Vocab: Epilation
Hair loss
Vocab: Genetic Effects
effects that appear in your offspring
Vocab: Genetic Mutations
changes in genetic code that appear in future generations
Vocab: Grenz Rays
rays with long wavelength and low frequency
Vocab: Karyotype
-an individual’s complete set of chromosomes
-a chromosome map that consists of a photograph or photomicrograph, of the human cell nucleus during metaphase, when each chromosome can be individually
perceived. The karyotype is constructed by extracting the individual chromosomes and pairing them on the map with their sister chromosomes. These chromosome
pairs are usually aligned by size, beginning with the largest pair and ending with the smallest pair
Vocab: Latent Period
the time between getting exposed and when symptoms occur.
Vocab: Manifest Illness
the symptoms of the illness
Vocab: Metaphase
-the phase of cell division in which chromosome damage caused by radiation exposure can be seen
-Chromosome aberrations (deviation from normal development or growth of structures that contain genetic material) and chromatid aberrations have been observed at metaphase
Vocab: Pluripotent Stem Cell
The hematopoietic system which consists of: Bone marrow, Circulating blood, Lymphoid organs (lymph nodes, spleen, and thymusgland). Cells of this system develop from a single precursor cell, the pluripotential stem cell. The following are other types of cells that originate from this one type of primary cell: lymphocytes, granulocytes, thrombocytes or platelets, and erythrocytes
Vocab: Prodromal Stage
beginning, stage. Severe nausea, vomiting, and diarrhea persist for as long as 24 hours.
Vocab: Radiodermatitis
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
Vocab: Repair and Recovery(cellular)
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.
Vocab: Somatic Effects
Biological damage to the exposed individual caused by exposure to ionizing radiation
Vocab: Somatic Tissue Reactions
if the consequences include cell killing and are directly related to the dose received, they are somatic tissue reactions. As the radiation dose increases, the severity of early somatic tissue reactions also increases
Are early tissue reactions common in diagnostic imaging?
No
The use of high-level fluoroscopy for extended periods can result in
Radiation-induced skin injuries
Possible high radiation dose consequences include:
• Nausea
• Fatigue
• Erythema (diffuse redness over an area of skin after irradiation) (Fig. 8.2)
• Epilation (loss of hair)
• Blood disorders
• Intestinal disorders
• Fever
• Dry and moist desquamation (shedding of the outer layer of skin) (Fig. 8.3)
• 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)
What is the most radiosensitive vital organ system in humans?
hematopoietic system
For persons with hematopoietic syndrome, survival time _________ as the radiation dose __________
Shortens, Inrceases
the most severely affected part of the GI tract is the
Small intestine
LD ___/___ for humans is perhaps the most accurate measure for human survival than any shorter period
50/60
repeated radiation injuries have a __________ effect
Cumulative
What is atrophy?
shrinkage of organs and tissues
What happens when an organ or tissue fails to recover from radiation exposure?
Necrosis or death
Organ and tissue response to radiation exposure depend on factors such as:
• 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
In 1898 after personally suffering severe burns, which he ultimately attributed to accumulated radiation, a Boston dentist, began investigating the potential hazards of radiation exposure. What was his name?
William Herbert Rollins
A single absorbed dose of 2 Gyt can cause radiation-induced skin erythema within
24 to 48 hours after irradiation
Desquamation, or shedding of the outer layer of skin, occurs at ______ radiation doses
high
Therapeutic ratio
The overall goal of any therapeutic treatment is to deposit the radiant energy to an overwhelming extent into an image-guided volume that both encloses the tumor and any microscopic extent of it and also includes a small added margin (this particular volume is called the planning target volume or PTV: it allows for uncertainties in planning and treatment delivery) while delivering a substantially lower dose to as much healthy surrounding tissue as possible
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
T or F: Both low and high radiation doses can cause chromosomal damage that may not be apparent immediately.
True
Are early effects deterministic or stochastic?
Deterministic
Early effects
Biologic effects of radiation that occur relatively soon after humans receive high doses of ionizing radiation
If someone has gastrointestinal syndrome, fatality primarily occurs as a result of
Catastrophic damage to the epithelial cells that line the gastrointestinal tract
Early tissue reactions, Late tissue reactions, Stochastic effects
