What 3 radiation syndromes is induced by total body exposure
What are the 3 specific exposures conditions when dealing with radiation syndromes
exposure must be acute (minutes)
total body or nnearly total body exposure must occur
exposure must be from an external penetrating source rather than ingested, inhaled or implanted radioactive sources
What amount of exposure induces hematopoeitic syndrome?
100 to 1000 cGy
What does LD50/60 mean?
lethal dose 50% in 60 days
50% of the exposed populatioon will be dead in 60 days
what is the lethal dose fro humans estimated to be?
350 to 450 cGy
Typically who is more resistant males or females?
the extremely young & old are typically more radiosenstive
although the affected person feel sgood, what is beginning to die
bone marrow stem cells
Depression of all blood cell counts
what is the primary cause of death from the hematopoietic syndrome
infection and hemmoraging after destruction of the bone marrow
what amount of exposure induces the gastrointestinal syndrome
1000 to 10,000 cGy
the small intestine is the most radiosensitive portion of the digestive system
what amount of exposure induces the cerebrovascular syndrome
5,000 cGy or more
In the stages of fetal development when is the embyro stage
day 10 to week 6
In the stages of fetal development when does it become a fetus?
at the end of week 6
The maximum permissible dose to the fetus during the entire gestational period from occupational exposure of the mother should not exceed 0.5 rem with monthly exposure not exceeding 0.05 rem
what is considered to be the most radiosensitive form of animals and humans
the embryo & fetus
in reguard to fetal effects of radiation, the prinicpal factors of importance are the dose and the stage of gestation at which it is delivered.
define late effects
the biologic response of low doses may not be observable for extended periods, ranging from years to generations
late effects are termed as _____ if body cells are involved
late effects are termed as _____ if reproductive (germ) cells are invovled
Latent period: The time interval between irradiation and the appearance of a malignancy is known as the latent period
the most important late somatic effects induced by radiation is
radiation is classified as a _____.
carcinogen, or cancer causing agent
___ ___ has been implicated as a cause of skin cancer, leuukemia, osteosarcoma, lung cancer, breast cancer, anf thyroid cancer.
** Skin cancer: Squamous cell and basal cell carcinomas have been the most frequently observed skin cancers following radiation exposure
Lung carcinoma was once known as
Radoon gas: The naturally occuring deposits of radioactive materials in the rocks of the earth decay through a long series of steps until they reach a stable isotope of lead. One of these steps involve radon gas.
ionizing radiation is known as a
Define mutation frequency
the number of spontaneous mutations that occur in each generation of an organism
Mutation frequency can be increased by any mutagenic agent, including radiation
If the mutation frequency in a generation is doubled by exposure to radiation dose then it is known as
waht is the goal of radiation therapy for cancer
to eradicate the tumor while not destaying normal tissues in the treatment field
Growth Fraction refers to the relationship between cancer cells proliferating and those cells resting
The rate at which tumor cells grow depend on these 3 major factors:
1) the division rate of proliferating parenchymal cells
2) the percentage of these cels in the tumor (GF), and
3) the degree of cell loss from the tumor
oxygen tension =
differing levels of oxygen availability for the tumor cells depending ontheir proximity to functioning blood vessels
no oxygen available
Date fromthe animal tumors estimate that approximately 15% or more of the tumor cell population may be hypoxic.
This is known as what?
therapy treatment are broken up and given in daily doses over an extended period of time but the total dose is the same
The biologic effects on tissue from fractionated radiation therapy depend on the 4 R's of radiation biology.
These are known as:
reapir of sublethal damage
the process by which hypoxic cells gain access to oxygen and become radiosenstive between radiation fractions
IMRT stands for
intensity modulated radiation therapy
what does TD5/5 mean?
Tissue dose associated with a 5% injury rate within 5 years