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what are 2 incidents of modern radiation incidents?
Three Mile Island and Chernobyl
Define Late effects
long-term effects such as malignant disease, local tissue damage, life-span shortening, genetic damage, and potential effects to the fetus.
Three Mile Island - what was the exposure and mile radius?
8 mrem at 10 miles
Three Mile Island - what was the addition of cancer deaths of population and what was the mile range?
.7 additional deaths at 50 mile radius
What is the suggestion in regards to death and three mile island
- political backlash against nuclear power will cause more deaths due to the production of power in the traditional ways
- 100 per year due to mining and transportation
- 125,000 per year chronic respiratory disease
- 1 million person-days of aggraved heart and lung symptoms
Why was Chernobyl more of a threat?
much larger area impacted and much higher exposure levels
statistics of Chernobyl
- of 444 workers on site
- 203 suffered acute radiation syndrome
- 100-200 rem (105 workers) - no deaths
- 200-400 rem (53 workers) - one died
- 400-600 rem (23 workers) - 7 died
- 600-1600 rem (22 workers) - 21 died
- study the distribution and cause of disease in human populations
- observation only, not experimentations
what is the focus of epidemiology of radiation been on
what are the limitations of epidemiology?
- incidence of cancer is compared to expected incidence
- increase may not be statistically significant
- not possible to isolate all factors
- dosimetry problems
NUMBER OF CASES PER 1 MILLION PEOPLE/ONE RAD
example: 1 million people exposed to 1 rad results in 6 more cases than expected, would be an absolute risk of 6
number of excess cases than what would be expected
- used when dose is unknown
- exposed group is compared to unexposed group
- ranges from 1-10
What risk types are preferred?
Absolute Risk and Relative Risk
what is the most radiogentic tumor
what is the type for adults
acute and chronic myeloid leukemia
what is the type for children
acute and chronic lymphocytic leukemia
what dx has the shortest latent period of any malignant dx?
leukemia at 5-7 years
what is the risk period for leukemia
considered 20 years
what is osteosarcoma?
what type of cancer was observed in radium dial painters?
osteosarcoma or bone cancer
what is the half-life of Radium? Where is it deposited?
1620 years. Bone
Why is Radium bone cancer not compared to diagnostic x-rays?
Radium emits high LET alpha and beta particles
with osteosarcoma or bone cancer what bones are most affected?
femur, mandible, and pelvis
- increased incidence not seen in chest fluoro study
- increased incidence was seen in miners
- attributed to radon
- most miners also smoked which compound problem
- increase of 6-8 times in non-smokers
- increase of 20 times in smokers
Thyroid Cancer - where did this turn up the most
what is the latent period for thyroid cancer
what is the response curve of thyroid cancer
- linear, non-threshold
- even 1 photon will cause damage
women are how many times more likely to develop radiation induced thyroid tumors over males and why
4 times greater risk - due to hormonal changes
can radiation induce this type of cancer
at what age do we see no increased risk
over 40 years of age
why continue with mammography?
benefits outweigh the risk
list the 9 conclusions
1 single exposure can elevate incidence of cancer 2. no radiounique cancer 3. almost all cancers increase with irradiation 4. breast, bone marrow, and thyroid especially radio-sensitive (mitotically active) 5. most prominent radiogenic tumor is leukemia 6. solid tumors of latent period of at least 10 years 7. age of exposed individual most important factor 8. increase in cancer incidence varies between organs and cancer types 9. dose-effect curves are assumed to be linear (linear, non-threshold) - as dose doubles incidence doubles. Law of bergonia and tribedaux
what is the largest organ of the body
what is the function of the skin
to cover, protect from microbes, control body temp, regulate blood flow, and excrete wastes
at what level is radiation induced damage most likely to occur
basal level or subcutaneous
skin may not regenerate at what exposure levels?
levels over 1000 rad - collimated local tissue dose not whole body dose
the male system is considered ___________except for the ___________which are ______ __________.
radio-resistant, testes, moderately radio-sensitive
in the male reproductive system
at what levels do we see temporary sterility,
at what levels do we see permanent sterility?
- 200-250 rad = temp
- 500-600 rad = perm
in the female reproductive system
the female system is _______ ________
and is a function of ___________
in females the function of age
what age group is more radio-resistant?
at younger ages more resistant
level changes and goes more sensitive as we grow older
chromosomal damage is considered for which reproductive system
male or female
considered for both systems
what part of the eye is not as radio-resistant as the other parts
what is the major outcome of exposure to the eyes
what is the latent period for issues with the eyes
up to 30 years
what is the threshold level (in rad)
may be 200 rad but this in not certain
hemopoietic systems consists of what
blood forming organs (marrow), circulating blood, and lymphoid system
where is this most likely found
in the blood forming marrow; primarily ribs, ends of long bones, vertebrae, sternum, and skull also includes the flat bones of the pelvis
why is marrow radiosensitive
blood forming stem cells
why is circulating blood radio-resistant
because it consits of post mitotic RBC and plateletes
what makes up the lymphatic system
lymph nodes, thymus, spleen, and some bone marrow
what is the primary purpose of the lymph system
to produce WBC
what is the sensitivity level of the lymph system
which is more senstive to radiation
blasts or cytes
blasts are more sensitive since they still have their nucleus
cytes no longer have a nucleus
cardiovascular system consists of
blood vessels and heart
cardiovascular system is ______ except for _____ _______. why
radio-resistant, endothelial cells (lining) may divide excessively leading to blockage.
small vessles are more radiosenstive than larger vessels (takes less to block)
The heart is
respiratory system consists of
nose, pharynx, trachea, and lungs
the respiratory system is _____ _____.
what is the only major long-term radiation effect and what is the dose this is seen at
fibrosis major effect seen after doses over 2500 rad
digestive system consists of
mouth, esophagus, stomach, small bowel, large bowel, and auxillary organs
digestive system is considered
moderately radio-sensitive - different portions have different radiosensitivities
SMALL BOWEL IS MOST RADIOSENSITIVE
WHAT IS THE DOSE FOR THE DIGESTIVE SYSTEM
doses of 500 rad can cause atrophy
doses over 1000 rad can permanently destory villi (motility and absorption)
liver is moderatley radio-sensitive - why
due to large blood supply
what dx usually results form damage to livers blood supply
urinary system consists of :
only long term effects are__ & ___ at what rad level?
kidneys, ureters, bladder and urethra
considered - relatively radio-resistant
- renal failure and atrophy
- 2500 rad
what is the functional part of the urinary system
paranchima (meaty portion) see damage quickly
stroma or vasculature - see damage less quick - supportive
growing bone and cartilage
what type of cells are radio-resistant?
why are osteoblasts and chondroblasts moderatley radiosenstive?
consists of stem cells
at what level do we see a halt in mitosis
at what level do we see permanent suppression in mitosis
100 rad see halt in mitosis
1000+ rad see permanent suppression in mitosis
CNS consists of:
sensitivity level is:
level we see damage and the damage is:
brain and spinal cord
2000 rad see necrosis and fibrosis due to damage to vascularity
life span shortening
no data supports that radiation causes life-span shortening - true or false
life-span shortening effects are due to :
due to the radiation induced effects such as leukemia
can not prove that radiation induced cancer
weakest or strongest area of understanding?
most data has been gained from experiments on
experiments with fuit flies - H J Muller's experiments
what was found via H J Mullers fruit fly experiments
- no increase in quality or types of mutations, only increase in incidence
- most mutations were recessive
- no threshold (followed linear, non-threshold)
- did not matter if dose was fractionalized or one large dose
what dose the dose part mean?
mutations are single hit and cumulative
define double dose
double dose - dose necessary to double the frequencey of genetic mutations
GSD - genetic significant dose - averages the gonadal exposure over an entire population (exposed and unexposed)
indicates the genetic effect of exposure on a population
what is the usual response?
what is the rad level that causes prenatal death (divide it down)
typically an "all or nothing" response
- 200 rad causes prenatal death
- day 1 to 80%
- day 9 to 30%
- as fetus ages sensitivity decreases
what exposure will be primarily at root cause
rare but from exposure in organgenesis
10 day precaution measures
28 day rule
10 day - limit to 1st 10 days after menustration onset - least likely to be pregnant
28 day - can be preformed up to 28 days after menustration
all or nothing response
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