RAD 201 Chapter 9 Flashcards

Questions and Answers

Radiation-induced cataracts in humans follow a ______ dose-response relationship.

Threshold, linear

Nonthreshold, nonlinear

Nonthreshold, linear

Threshold, nonlinear (correct)

Among the atomic bomb survivors, the number of leukemia victims has _____ since the late 1940s and early 1950s. However, the occurrence rates of other radiation-induced malignancies have continued to _ since the late 1950s and early 1960s.

Increased slowly; decrease

Slowly declined; escalate (correct)

Increased rapidly; decrease

Rapidly declined; decrease

To assess the magnitude and severity of late effects on the exposed population from the 1986 nuclear power station accident at Chernobyl, which follow-up is necessary?

Follow-up is not necessary

Long-term follow-up studies (correct)

Minimal follow-up

Short-term follow-up studies

Which of the following late effects caused by exposure to ionizing radiation is considered to be the most important?

Cancer Signup and view all the answers

The human body can incorporate radium into bone because it is chemically similar to:

Calcium Signup and view all the answers

During the 1950s and 1960s, the Navajo people developed lung cancer years after their exposure to uranium mining. This provides an example of which of the following?

Late stochastic effects Signup and view all the answers

In general, laboratory experiments with mice prove that cataracts may be induced with doses of ionizing radiation as low as:

0.1 Gyt Signup and view all the answers

In which of the following human populations is the risk for causing a radiation-induced cancer not directly measurable?

All patients in diagnostic radiology subjected to a radiation dose below 0.1 Sv Signup and view all the answers

Mutations in genes and DNA that occur at random as natural phenomena are called:

Spontaneous mutations Signup and view all the answers

Existing data on radiation-induced genetic effects in humans:

Are both contradictory and inconclusive Signup and view all the answers

When a prediction is made that the number of excess cancers rises as the natural incidence of cancer increases with advancing age in the population, the risk is considered to be:

Relative Signup and view all the answers

What is the mean value of the radiation doubling equivalent dose for humans, as determined from studies of the children of the atomic bomb survivors of Hiroshima and Nagasaki?

1.56 Sv Signup and view all the answers

Genetic effects from exposure to ionizing radiation occur as a result of radiation-induced damage to the DNA molecule in which of the following?

Sperm and Ova Signup and view all the answers

What do agents such as specific chemicals, viruses, and ionizing radiation have in common?

They are all mutagens that may increase the frequency of mutations Signup and view all the answers

Which of the following are sources of low-level radiation exposure?

1, 2, and 3 Signup and view all the answers

During the preimplantation stage of development, if the fertilized ovum is irradiated with a dose in the range of 0.05 to 0.15 Gyt, which of the following will result?

Embryonic death Signup and view all the answers

After the Chernobyl disaster in 1986, what was administered to children to block the gland's uptake of iodine-131, which can cause thyroid cancer?

Potassium iodide Signup and view all the answers

Epidemiologic studies are of significant value to radiobiologists who use the information from these studies to formulate dose-response curves for making predictions of the risk of ____________ in human populations exposed to low levels of ionizing radiation.

Cancer Signup and view all the answers

Radiation-induced abnormalities are caused by unrepaired damage to:

DNA molecules in the sperm or ova of an adult Signup and view all the answers

Some mutations in genetic material occur spontaneously, without a known cause. In humans, a hereditary disorder is present in approximately _________ of all live births in the United States.

10% Signup and view all the answers

Currently, evidence of radiation-induced hereditary effects has not been observed in persons employed in diagnostic imaging or in persons undergoing radiologic examinations. Even with this information, it is still recommended that:

1 and 2 only Signup and view all the answers

Radium decays with a half-life of:

1622 years Signup and view all the answers

The term linear nonthreshold relationship implies that the biologic response to ionizing radiation is:

Directly proportional to the dose all the way down to levels approaching zero Signup and view all the answers

Genetic mutations at the molecular level are called:

Point mutations Signup and view all the answers

Studies showed that postpartum patients treated with ionizing radiation for relief of mastitis are a group of individuals in whom the results of radiation exposure to healthy breast tissue indicate that radiation:

Can cause breast cancer Signup and view all the answers

Study Notes

Radiation-Induced Effects

Radiation-induced cataracts exhibit a threshold, nonlinear dose-response relationship.
Among atomic bomb survivors, leukemia cases slowly declined, whereas rates of other radiation-induced malignancies have steadily escalated since the late 1950s.
Long-term follow-up studies are essential for assessing late effects on populations exposed to the Chernobyl disaster.

Importance of Health Risks

The most critical late effect of ionizing radiation exposure is cancer.
Radium can be integrated into bones due to its chemical similarity to calcium.

The Navajo miners exposed to uranium exemplify late stochastic effects, developing lung cancer years post-exposure.
Laboratory studies indicate cataracts can occur with ionizing radiation doses as low as 0.1 Gyt.

Risk Measurement and Genetics

The risk for radiation-induced cancer in diagnostic radiology patients receiving doses below 0.1 Sv is deemed not directly measurable.
Spontaneous mutations are genetic changes that arise randomly as natural occurrences.

Genetic Effects of Radiation

Data on genetic effects from radiation exposure in humans is contradictory and inconclusive.
As cancer incidence rises naturally with age, the risk attributed to radiation is classified as relative.

Dosimetry and Genetic Insights

The mean radiation doubling equivalent dose for humans, based on studies of atomic bomb survivors, is 1.56 Sv.
Genetic effects from radiation exposure occur in the sperm and ova, but not in somatic cells.

Mutagens and Radiation Sources

Ionizing radiation, chemicals, and viruses are all mutagens, capable of increasing mutation frequencies in populations.
Sources of low-level radiation exposure include X-rays, employment-related exposures, and natural background radiation.

Developmental Impact and Public Health

Irradiation of the fertilized ovum during the preimplantation stage can lead to embryonic death if exposed to doses between 0.05 to 0.15 Gyt.
Following the Chernobyl incident, potassium iodide was administered to prevent thyroid cancer from iodine-131 exposure.

Epidemiological Studies and Health Risks

Epidemiological studies inform radiobiologists about dose-response curves to predict cancer risk from low-level ionizing radiation exposures.
Radiation-induced damage primarily affects DNA molecules in sperm or ova, implicating hereditary effects.

Hereditary Disorders and Safety Recommendations

Approximately 10% of all live births in the U.S. involve hereditary disorders.
Despite no observed hereditary effects from exposure in diagnostic imaging, ongoing safety practices include effective gonadal shielding and maintaining radiation exposure as low as reasonably achievable (ALARA).

Radium and Radiation Response

Radium has a half-life of 1622 years, indicating its long-term presence in the environment.
The concept of a linear nonthreshold relationship suggests that biological response to radiation is directly proportional to the dose, including very low levels.

Mutation Types

At the molecular level, genetic mutations are categorized as point mutations.
Evidence indicates that scattered radiation can lead to breast cancer in postpartum patients treated with ionizing radiation for mastitis.

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Description

Test your knowledge with flashcards from RAD 201 Chapter 9. This chapter focuses on the effects of radiation exposure, specifically terms like dose-response relationships and radiation-induced malignancies. Perfect for students preparing for exams in radiology or related fields.