-
The total body response to radiation is presented in terms of 3 ______ ______
Radiation Syndromes
-
Characteristics of each syndrome are dependent on the ______ received and exposure conditions.
dose
-
What are the 3 specific exposure conditions that apply in dealing with radiation syndromes?
- 1. exposure must be acute (minutes)
- 2. total body or nearly total body exposure must occur
- 3. exposure must be from an external penetrating source rather than ingested, inhaled, or implanted radioactive sources.
-
What are the 3 syndromes
- Hematopoetic
- Gastrointestinal
- Cerebrovascular
-
What is the hemopoetic syndrome
blood syndrome that has a deficiency of WBCs, lymphocytes and platelets.
-
What is induced by a total body dose of 100-1000 cGy?
Hematopoetic Syndrome
-
In hematopoetic syndrome LD 50/60 for humans is estimated to be between_____ and ______ by varies with ____, _____, and _______
- 350-450 cGy
- age, health, and gender
-
Who is more resistant to get the hematopoetic syndrome?
- females and the middle aged person
- males and very young and old are more sensitive
-
What is the depression of all blood cell counts
pancytopenia
-
Note for hematopoetic syndrome
- most patients receiving less than 300cGY will survive and eventually recover over 3-6 month period
- After 300-500 cGy death may occur in 4-6 weeks
- After 500-1000 cGy death is likely within 2 weeks.
- No record exists of human survival when the total body dose exceeds 1000 cGy.
-
Which syndrome is induced if the total body dose is between 1000 and 10,000 cGy?
Gastrointestinal Syndrome
-
Which syndrome can also be induced at a dose as low as 600 cGy and overlaps with the cerbrovascular syndrome at doses of 5000 cGy or more?
gastrointestinal
-
What is the mean survival time for the gastrointestinal syndrome?
3-10 days or up to 2 weeks with medical support
-
How does the gastrointestinal syndrome occur?
as a result of damage to the gastrointestinal tract and bone marrow.
-
What is the most radiosensitive portion of the digestive system?
small intestines
-
After exposure doses of _______, severe depopulation of crypt cells leads to partial or complete denudation (wearing away) of the villi lining the lumen of the small intestine.
1000 cGy
-
This syndrome was formerly known as the _____ _____ _____ _______and occurs exclusively after doses of 10,000 cGy or more.
- central nervous system syndrome
- Cerebrovascular syndrome
-
Which syndrome can overlap the gastrointestinal syndrome because it can be induced by a dose as low as 5000 cGy?
Cerebrovascular Syndrome
-
How fast can deat occur after the cerbrovascular syndrome doses at over 10,000 cGy?
several days or less
-
what can damage the developing embryo and fetus in utero?
radiation
-
how is radiation damage manifested when given in utero?
as lethal effects, congenital abnormalities present at birth or late effects observed years later.
-
How can the below effects be produced?
lethal effects, congenital abnormalities present at birth or late effects observed years later.
- 1. irradiation of the sperm or ovum before fertilization, thus resulting in inherited effects
- 2. exposure of the fetus to radiation , thus resulting in congenital defects.
-
What are the newly formed balls of cells known as?
embryo
-
At what stage is it considered an embryo?
10 days to 6 weeks
-
At the end of the 6th week of pregnancy, what is it called?
fetus
-
Unlike the adult the _____ _____ _____ is responsive to radiation and can be damaged at relatively low doses.
fetal nervous system.
-
Hematopoetic Syndrome dose range is
100-1000 cGy
-
Hematopoetic Syndrome recovery time is
dose dependent- 3 weeks to 6 months; some people do not survive
-
Hematopoetic Syndrome time of death?
3 weeks to 2 months
-
Hematopoetic Syndrome organ and system damaged?
Bone marrow
-
Hematopoetic Syndrome signs and symptoms
- Decreased # of stem cells in bone marrow
- increased amt of fat in bone marrow
- pancytopenia (depression of all blood counts)
- anemia
- hemorrhage
- infection
-
Gastrointestinal Syndrome dose range
1000-5000 cGy
-
Gastrointestinal Syndrome time of death
3-10 days
-
Gastrointestinal Syndrome organ and system damage
small intestine
-
Gastrointestinal Syndrome signs and symptoms
- denudation (wearing down) of villi in small intestine
- neutropenia
- infection
- bone marrow depression
- electrolyte imbalance
- watery diarrhea
-
Gastrointestinal Syndrome recovery time
none
-
Cerebrovascular Syndrome dose range
> 5000 cGy
-
Cerebrovascular Syndrome time of death
<3 days
-
Cerebrovascular Syndrome organ and system damaged
brain
-
Cerebrovascular Syndrome signs and symptoms
- Vasculitis
- edema
- meningitis
-
Cerebrovascular Syndrome recovery time
none
-
What should not exceed .5 rem (5 mSv) with monthly exposure not exceeding .05 rem )0.5 mSv) ?
The maximum permissible dose to the fetus during the entire gestational period from occupational exposure of the mother
-
The _____ _______ dose to the fetus during the entire gestational period from occupational exposure of the mother should not exceed .5 rem (5 mSv) with monthly exposure not exceeding .05 rem )0.5 mSv) ?
maximum permissible
-
what are the most radiosensitive forms of animals and humans?
embryo and the fetus
-
in regard to fetal effects of radiation, the principal factors of importance are......
the dose and the stage of gestation at which it was delivered
-
Because the latent period for an effect from radiation is inversely proportional to radiation does, the biological response to low dose is not observable for extended periods of time ranging from years to generations. These effects are known as late effects and are termed ____ _____ if body cells are involved and ____ _____ if reproductive (germ) cells are involved
- somatic effects
- genetic effects
-
What is the time interval between irradiation and the appearance of a malignancy?
latent period
-
What is the most important late somatic effect induced by radiation?
carcinogenesis
-
Radiation is classified as a
carcinogen or cancer-causing agent
-
What is considered to be an all or nothing event?
carcinogenesis
-
Any dose no matter how low, has some potential of inducing _____
cancer
-
What is a non threshold even with the probability of an effect increasing as the dose increases?
cancer induction
-
Carcinogenesis is an example of a ____ _____ in which every dose carries some magnitude of risk
stochastic effect
-
The latent period for leukemia induction by radiation is usually ____ to _____ _____ with the peak incidence approx____ to ____ _____ after exposure
-
Radiation induced solid tumors have a latent period ranging from
20-30 years or longer
-
When and where was the 1st radiation induced skin cancer?
1902 on the hand of a radiologist
-
what have been the most frequently observed skin cancers following radiation exposure?
squamous cell and basal cell carcinomas
-
when the young female watch dial painters licked their brushes that had radium paint on the tip to paint the clock faces, what did they develop in 1915-1930
osteosarcoma or bone cancer
-
What is the naturally occurring deposits of radioactive materials in the rocks of the earth and decay thru a long series of steps until they reach a stable isotope of lead?
Radon gas
-
The dose range from 1200-6000 cGy was a popular treatment for what and had a 100 fold increase in thyroid cancer
Irradiation of the enlarged thymuses in children before the 1930s
-
Ionizing radiation is known as a
mutagen
-
Note
somatic late effects can occur in an irradiated individual, and exposure of reproductive (germ) cells in that individual may affect future generations.
-
The # of spontaneous mutations that occur in each generation of an organism is
mutation frequency
-
If the mutation frequency in a generation is doubled by exposure to radiation, the radiation dose is known as
doubling dose
-
What is the TD 5/5 for bladder
6000 cGy
-
What is the TD 5/5 for the rectum
6000 cGy
-
What is the TD 5/5 for the Lens
500 cGy
-
What is the TD 5/5 for the Fetus
200 cGy
-
What is the TD 5/5 for the heart
4500 cGy
-
What is the TD 5/5 for the Intestine
4500 cGy
-
What is the TD 5/5 for the kidney
1500 cGy
-
What is the TD 5/5 for the Liver
2500 cGy
-
What is the TD 5/5 for the lung
3000 cGy
-
What is the TD 5/5 for the spinal cord
4500 cGy
-
What is TD 5/5
The tissue dose associated eith a 5% injury rate within 5 years
-
what is TD 50/5
tissue dose associated eith a 50% injury rate within 5 years
-
what is TD 5/5 for the brain
5000-6000 cGy
-
What is the TD5/5 for the esophagus
6000 cGy
-
What is the goal of Radiation therapy
To eradicate the tumor all the while not destroying normal tissue
-
___ ____ can be induced in tumor AND in normal tissues
biologic damage
-
The tolerance dose of the normal tissue limits the ____ that can be administered to the tumor
dose
-
What is the functional cells of an organ (mutant cells)
Parenchymal
-
What are connective tissue cells called
Stromal
-
Describe cells belonging to group 1 of parenchymal
- viable
- actively mitotic
- responsible for tumor growth
-
the % of group 1 cells in a tumor varies from ___ to ____ and is termed ___ ____
-
The ____ _____ typically decreases as the size (volume) of the tumor increases
growth fraction
-
describe cells belonging to group 2 of parenchymal
- viable
- not dividing
- basically in the G0 phase
-
Which cells have retained the ability to re enter the cell cycle and divide if properly stimulated?
G0 phase or group 2
-
Which group is not viable
3 and 4
-
The rate at which tumors grow depends on 3 major factors
- the division rate of proliferating parenchymal cells
- the % of these cells in the tumor
- the degree of cell loss from the tumor
-
What is characteristically unorganized compared with that of normal cells
tumor growth
-
During the early stages, tumors begin to outgrow their_____ _____
vascular supply
-
Differing levels of O2 availability is
oxygen tension PO2
-
Tumors located more than 200 um from the nearset blood vessels (capillaries) are ____ and unable to proliferate
anoxic
-
What do anoxic cells that have died form?
necrotic area
-
Tumor cells closest to blood vessels are well oxygenated and called _____ and are actively dividing and compose the GF of the tumor
oxic cells
-
Gradually decreased O2 tensions are
hypoxic cells
-
15% or more of the tumor cell population may be ____ and this is known as the ___ ____ of the tumor
-
The vasculature network that forms in each growing tumor with factors such as division rate, GF, cell loss, ultimately gives rise to ___,____,and ____ cell populations in the tumor.
-
What is the #1 radiosensitizer
O2
-
The biologic effects on tissue from fractionated radiation therapy depend on the
- 4 Rs
- Repopulation
- Redistribution
- Repair
- Reoxygenation
-
What are the most radiosensitive phases
G2 and M
-
What results in a redistribution of surviving cells after radiation
Partial Synchronization
-
When you irradiate a cell population that is in various phases, typically results in death of cells in G2 and M and survival to cells in S, this process is known as
partial synchronization
-
What has occurred within hours of radiation exposure in normal and tumor cells in vitro?
Repairs of sublethal damage
-
What takes advantage of repair processes in normal tissues that are active between radiation fractions?
Fractionated radiation treatment
-
Repair of sublethal damage is ____ dependent
O2
-
Because a proportion of tumor cells are thought to be ____, tumors in general are presumed to be incapeable of repairing sublethal radiation damage as efficiently as normal tissues
hypoxic
-
Which R only applys to tumors?
Reoxygenation
-
What is the process by which hypoxic cells gain access to O2 and become radiosensitive between radiation fractions?
reoxygenation
-
what decreases during fractionation of xrays and gamma rays
-
what 5 methods have been used with varying degrees of success of improved tumor response
- radiosensitizers
- radioprotectors
- high LET radiations
- chemotherapy agents
- hyperthermia (heat)
-
what related the treatment schedule in terms of total dose and time with clinical outcome including early and late effects and tumor cure?
Isoeffect curves
-
The use of ___ ____ led to treatment schedules fro fractionate XRT that gave a high probability of tumor control without exceeding the tolerance of normal tissue
Isoeffect curves
-
What has reduced radiation toxicity to surrounding tissues altering the ratio of normal tissue dose to tumor dose?
- IMRT
- intensity modulated radiation therapy
|
|
