an increase of exposure results in __________ chance of interaction.
an increase
an increase of exposure __________ severity.
does not increase
our radiation protection guides are based on the late effects of radiation and on:
linear, nonthreshold dose-response relationship
in late effects, diagnostic exposure is:
low LET and chronic
late effects are the result of:
while the early effects result from:
late: low doses delivered over long periods of time
early: high doses of radiation
Personnel in diagnostic imaging experience _________________________ over a long time span.
low doses and low LET periodically
two primary long term effects resulting from low dose radiation over long periods of time:
malignancy
genetic effects
there is not a specific dose to relate to various late effects such as:
malignancy
genetic effects
life-span shortening
local tissue effects
what is the method of choice when studying late effects?
epidemiological method
when a large number of people exposed to toxic substance requiring considerable statistical analyses:
epidemiological method
name some problems that arise with the epidemiological method:
the dose is usually not known but presumed to be low
the frequency of response is very low
**this results in less statistical accuracy than early effects**
inflammation of the skin caused by exposure to x-rays or emissions from radioactive particles:
radiodermatitis
give examples of radiodermatitis:
callused, discolored and weathered appearance
skin very tight and brittle
late-developing carcinoma
(erythema early effect takes 200 rads)
in chromosomal effects of radiation to local tissue, _______________ is the early effect while _____________ is the late effect.
hematologic depression (25 rads)
leukemia
chromosomal damage in the _________________ can take place in both early and late effects
circulating lymphocytes
(early: 5 rads chromosomal aberration)
may not become apparent until many years after the radiation exposure:
low dose aberration
radiation exposure can remain in the peripheral lymphocytes for as long as:
20 years
(if lymphocyte stem cells are irradiated, they may not undergo replication and maturation for many years - this explains the possible delay)
who developed the first cyclotron, when, and what was its principle use?
E. O. Lawrence
1932
to produce radionuclides for use in nuclear medicine, and fluorine-18 in PET
where are the largest cyclotrons in the world located?
Argonne National Laboratory in the U.S. and CERN in Switzerland
describe how the cyclotron contributed to cataracts:
physicists used a fluorescent screen to locate the high energy beam which resulted in very high doses to the lens of the eye
by 1960, several hundred cases of cataracts were reported in the high-energy physics
where do high energy cataracts form?
in the posterior pole of the lens
concerning cataracts, radiosensitivity of the lens is ____________, the latent period varies from ___________ years, and the average latent period is _____ years.
age dependent
5-30 years
15 years.
High LET such as ______________ radiation have a ______ RBE for the production of cataracts.
neutron and proton
high
dose-response relationship for cataracts is:
nonlinear, threshold
concerning cataracts, acute threshold is _________; chronic threshold is approximately _________.
200 rads (acute)
1000 rads (chronic)
in CT, a patient can receive up to _______ per slice intersecting the lens of the eye. On average, the lens may be intersected ______ resulting in _______ to the lens of the eye.
5 rads
twice
10 rads
concerning the late effects of radiation in life-span shortening, dose response is:
linear, nonthreshold
concerning the late effects of radiation in life-span shortening - at worst, humans can expect a reduced life span of:
approximately 10 days per rad
give some examples of life-span shortening:
radiation worker: 12 days
being male rather than female: 2800 days
heart disease: 2100 days
being married: 2000 days
one pack of cigarettes a day: 1600 days
working as a coal miner: 1100 days
cancer: 980 days
30 pounds overweight: 900 days
airplane crashes: 1 days
motor vehicle accident: 200 days
the period after the prodromal stage of the acute radiation syndrome during which there is no visible sign of radiation sickness:
latent period
time period a person could actually die from a disease brought on by radiation:
risk period
what are the three types of risk estimates in late effects of radiation?
relative risk
excess risk
absolute risk
when one observes a large population for late radiation effects without having any precise knowledge of the radiation dose to which they were exposed:
relative risk
determined by the number of observed cases in the irradiated population and comparing
them with the number that would have been expected on the basis of known population levels:
excess risk
when one must assume a linear dose-response relationship and if the dose-response relationship is assumed to be nonthreshold, then only one dose level is required:
absolute risk
which type of risk estimate deals with observed or expected cases?
relative risk
name some human population groups affected by leukemia as a radiation-induced malignancy:
atomic bomb survivors
american radiologist
radiation therapy patients
children irradiated in utero
radiation-induced leukemia follows what type of dose-response relationship?
linear, nonthreshold
describe leukemia cases in atomic bomb survivors:
from 100,000 atomic bomb survivors, cases hit a plateau at 5 years and declined slowly for approximately 20 years
describe the latent and at-risk periods for leukemia as a radiation-induced malignancy:
latent period of 4 to 7 years
at-risk period of approximately 20 years
give some causes of leukemia occurring as a radiation-induced malignancy:
radiologist receiving over 100rads/yr
ankylosing spondylitis patients receiving radiation for relief
radiation therapy patients relapsing with leukemia
when studying the effects of cancer as a radiation malignancy, ______ of all deaths are due to cancer which can obscure the data.
20%
list three examples of thyroid cancer occurring as a radiation-induced malignancy:
500 rads for thymic enlargement in newborns resulted in thyroid nodules and cancer 20 years later
native children of rongelap atoll in 1954 were exposed to an excess of 1200 rads from the fallout of a hydrogen bomb test
chernobyl 1986, recent studies have shown no excess leukemia or cancer, but there was an increase in thyroid nodularity
give an example of bone cancer occurring as a radiation-induced malignancy:
1920-1930 watch dial painters exposure to high amounts of radium (half-life 1620 years); ingested radium metabolizes like calcium which resulted in as much as 50,000 rads to the bone
today tritium and promethium is used for the glow purpose without the excessive exposure
concerning skin cancer as a radiation-induced malignancy, give the following:
B) how it begins: radiodermatitis
induced by: radiation therapy orthovoltage (200-300kVp) or superficial xray (50-150kVp)
latent period: approximately 5-10 years
risk: 500-2000 rads relative risk of 4:1, 4000-6000 rads risk of 14:1, 6000-10000 rads risk of 27:1
describe aspects of breast cancer occurring as a radiation-induced malignancy:
patients were treated for TB with fluoroscopy of the chest to induce a pneumothorax in affected lung
patients would receive as much as several hundred rads per treatment
the relative risk of radiation induced breast cancer due to this procedure was found to be 10:1
patients also treated with 75 to 1,000 rads for postpartum mastitis resulting in a relative risk factor of 3:1
atomic bomb survivors of 10 rad or more showed a relative risk of 4:1
describe some aspects/locations of lung cancer occurring as a radiation-induced malignancy:
50% of bohemian mines of germany died of lung cancer
today it is known that radon found in the mines contributed to the lung cancer of these miners
radiation exposure in colorado mines are contributed to high levels of uranium (half-life 10,000,000,000 years)
a decay product of uranium is radon, a radionuclide capable of emanating through rock to produce a high level in the air to be breathed
describe some aspects of liver cancer occurring as a radiation-induced malignancy:
thorium dioxide made up 25% of thorotrast media used during 1925-1945 for angiography
latent period of 15 to 20 years
thorium dioxide deposited in phagocytic cells of the reticuloendothelial system and concentrated in the liver and spleen
concerning late effects, give the risk period for:
bone cancer
leukemia
and the latent period for:
skin cancer
leukemia
liver
thyroid
cataracts
bone cancer: 50 yrs
leukemia: 20 yrs
skin cancer: 5-10 yrs
leukemia: 4-7 yrs
liver: 15-20 yrs
thyroid: 5-10 yrs
cataracts: 5-30 yrs
give information concerning total risk of malignancy when it comes to three mile island:
2,000,000 people residing in 80 km radius near the susquehanna river in pennsylvania
ave. doses were 160 km-1.5 rad, 80km-8mrad
20% of population will have cancer considering statistics not taking into account the additional exposure from three mile island
prediction is 1.2 deaths due to exposure
be familiar with this chart:
BEIRS: Biologic Effects of Ionizing Radiation
a relationship in which the increased incidence of cancer is a constant number of cases after a minimal latent period:
absolute age-response relationship
a relationship where the increased incidence of cancer is proportional to the natural incidence:
relative age-response relationship
what are the three main concerns dealing with radiation and pregnancy (before, during, after)?
before: concern with interrupted fertility
during: possible congenital effects in newborns
after: related to genetic effects
____________ irradiation does NOT impair fertility.
low-chronic
describe what we know about the risks of radiation during pregnancy (in utero):
all observations point to first trimester during pregnancy as the most radiosensitive period
the first 2 weeks of pregnancy may be of least concern because the response is all-or-nothing