Late Tissue/Stochastic Effects Flashcards
a point or level at which a response or reaction to an increasing stimulation first occurs.
Threshold
indicates that a radiation absorbed dose of any magnitude has the capability of producing a biologic effect.
Nonthreshold effect
The ______ is demonstrated graphically through a curve (the dose–response [DR] curve) that maps the observed effects of radiation exposure in relation to the dose of radiation received.
radiation dose–response relationship
Appear months or yeas after exposure and are classified as either stochastic or tissue reactions
Late somatic effects
The _____ model predicts that the number of excess cancers will increase as the natural incidence of cancer increases with advancing age in a population
relative risk
The _______ model estimates that a specific number of malignancies will occur as a result of exposure
absolute risk
Radiation causes [dominant/recessive] mutations
Recessive
Currently, evidence of radiation-induced hereditary effects has not been observed in persons employed in diagnostic imaging or in patients undergoing radiologic examinations. Even with this information, it is still recommended that
all radiation exposure be maintained as low as reasonably achievable (ALARA).
During the 1950s and 1960s, the Navajo people of Arizona and New Mexico who mined uranium for fuel for nuclear weapons and power plants developed lung cancer years after their exposure. This provides an example of which of the following?
Late stochastic effects
During the preimplantation stage of development, the fertilized ovum divides and forms a ball-like structure containing undifferentiated cells. If this structure is irradiated with a dose in the range of 0.05 to 0.15 Gyt which of the following will result?
Embryonic death
Genetic mutations at the molecular level are called
point mutations.
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 of adults
Which of the following late effects caused by exposure to ionizing radiation is considered to be most significant?
Cancer
When a prediction is made that the number of excess cancers will increase as the natural incidence of cancer increases with advancing age in the population, the risk is considered to be:
Relative
What is the mean value of the radiation doubling dose for humans, as determined from studies of the children of the atomic bomb survivors of Hiroshima and Nagasaki?
1.56 Sv
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%
Radiation-induced cataracts in humans follow a ______ dose–response relationship.
threshold, nonlinear
What is the correct order of the major response to ARS (acute radiation syndrome)?
prodromal, latent, manifest, death/recovery
Absolute risk model estimates:
Malignancies that will occur as a result of irradiation
As radiation dose increases, the severity of early tissue reactions:
Increases
Which body system is the most radiosensitive?
Hematopoietic
Somatic cells divide through the process of:
Mitosis
Cancer and genetic effects are examples of:
Stochastic effects
T/F: A normal human has 46 different chromosomes composed of 23 pairs in each somatic cell.
True
T/F: Organogenesis lasts approximately from 10 days to 12 weeks post-conception.
True
Experiments with mice show that cataracts may be caused by doses as low as:
0.1 Gy
Gastrointestinal syndrome has a threshold dose of:
6 Gy
