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