CHAPTER 5 - Effects of Long-Term Exposure to Radiation
What is the all-or-nothing response of an embryo?
Embryos that survive display the all-or-nothing response If prenatal death does not happen, visible signs of abnormalities are unlikely, as injured cells are repaired or replaced
True or False. Currently, the incidence of leukemia among American radiologists is higher than other physicians
False
Using Table 5-2 describe the population & exposure, and effects observed for each of the following epidemiologic investigations that form the basis of current cancer dose-response estimates in human populations: 1. Ankylosing Spondylitis 2. Postpartum Mastitis Study 3. Radium Dial Painters
1. patients that are treated with radiotherapy to the spine 2. treated with radiotherapy for post party acute mastitis 3. Young women who injested radium ex. licking brushes
What percentage of the annual GSD comes from natural sources?
102 mrem (78%) comes from natural background radiation
What is the exposure range for thyroid cancer
120-6000 Rads
How many mrem do diagnostic x-rays contribute to the annual GSD?
20 mrem (15%) comes from medical sources
Skin Carcinoma latent period? doses exposed?
5-10 years 500 to 2000 rads - relative risk 4-1 6000 to 10,000 rad range 27-1 risk
What is the annual GSD in the US in mrem
Annual GSD from all radiation sources is 130 mrem
What populations have shown an increase in the incident of leukemia?
Atomic bomb survivors Ankylosing spondylitis treated with radiation Radiololgists
From what population do sources of data on the incidence of radiation-inducted cancer com from
Atomic bomb survivors Medically exposed patients Occupationally exposed personnel Populations who receive high natural background exposure
What population showed an increase in the incidence of lung cancer?
Increased incidence shown in miners of uranium & pitchblende.
Define the doubling-dose and state its range in rads/grays.
Is dose of radiation required per generation to double the spontaneous mutation rate Doubling dose for humans is in the range of 50 to 250 rads (0.5 and 2.5 Gy) for each generation
What is the latent period for both benign and malignant nodules?
Latent period for benign nodules is 3 to 35 years Malignant nodules is 10 to 35 years
What is the latent period for breast cancer?
Latent period varies 10 to 40 years
List some of the radiation-induce malignancies
Leukemia , skin carcinoma, thyroid cancer, breast cancer, osteosarcoma (bone cancer) lung cancer
With _____ LET, breast cancer risk is _______ dependent?
Low age dependent
Does each stage of fetal development have the same response to radiation? Why or why not?
No there are 3 stages Fetus has 3 stages of development Pre-implantation Major organogenesis Fetal or growth stage *Each stage has a different response to radiation ---Caused by relative radiosensitivity of tissues at time of exposure
What are the principle effects of radiation to the fetus?
Prenatal or neonatal death Congenital abnormalities Growth impairment Reduced intelligence Genetic abnormalities Cancer induction
If a fetus is irradiated in the first nine days post-conception, what can happen?
Radiation during this stage can cause prenatal death
Match the following: a. relative risk b. absolute risk c. excess risk ____ Can be determined when at least two different dose levels are known. ____ Can be used when radiation dose is not exactly known. ____ When the number of cases in the irradiated population can be observed, it can be compared with the number that is normally expected.
Relative risk- When radiation dose is not exactly known (1 is normal= no risk, 10 highest) Absolute risk- Can be determined when at least two different dose levels are known. ( Excess risk- When the number of cases in the irradiated population can be observed, it can be compared with the number that is normally expected.
True or False There is no evidence of radiation-induced leukemia in studies of American radiographers.
True
True or False. The low doses received during mammography have been shown to increase the risk of breast cancer.
false
What populations demonstrated an increase in thyroid cancer?
infants with enlarged thyroid being treated with radiation
Describe the genetically significant dose (GSD).
is an average calculated from gonadal dose received by entire population Takes into account the expected contribution of these people to children in future generations
Leukemia latent period? risk period Doses that people were exposed to?
latent period of 4-7 years At risk period of 15 - 20 years 100-2000 Rad
What populations demonstrated in increase in skin carcinoma?
people treated with radiation for acne and ringworm
what is the formula for Relative Risk What is the formula for Excess Risk What is the formula for Absolute risk
relative risk= observed cases/ expected cases Excess cases=observed cases- expected cases number of cases/number of persons/per rad /per year
What population demonstrated osteosarcoma?
watch-dial painters in early 1920s
Are the low doses associated with occupational exposure to radiation considered carcinogenic?
you don't know, you cannot say for certain