TD 5/5 indicates the dose requred to cause a 5% chance of injury to people irradiated within ___following exposure.
B. TD 5/5 indicate 5% chance of injury within 5 years following exposure.
LD 50/30 indicates the dose likely to cause death in 50% of the population within ___ following exposure.
D. LD 50/30 is the lethal dose to 50% of the population in 30 days following exposure
The TD 5/5 for the whole kidney using standard fractionation is approximately:
C. The TD 5/5 for the whole kidney is about 23 Gy. Lower volumes of the kidney would increase the tolerance dose up to 50 Gy
The TD 5/5 for the whole brain using standard fractionation is approximately:
B. TD 5/5 for the whole brain is 45 Gy. Lower the volume of brain would increase the tolerance up to 60 Gy
The period of organogenesis normally occurs during the ____ week(s) of fetal development.
A. Organogenesis, or the formation of organs, occurs during the second through the eight weeks of fetal development
The radiosensitivity in tissue may be enhanced by:
A. Oxygen enhances the sensitivity to radiation by increasing the possibility of free radical production
The phase of cellular division most resistant to radiation is the ___phase.
D. The "S" phase is most resistant to radiation. The "S" phase is the stage of DNA synthesis
The immediate symptoms that appear after an acute radiation exposure are called:
D. The prodromal syndrome occurs immediately after a large acute radiation exposure. Nausea, of the prodromal stage of radiation sickness
The law of Bergonie and Tribondeau states that ionizing radiation is more effective against cells that are:
A. Cells that are highly mitotic, undifferentiated and have a long dividing life are most responsive to radiation according to Bergonie and Tribondeau
The development of a radiation-induced cancer is known as a (deterministic/strochastic) affect.
stochastic. Stochastic effects occur long after radiation exposure; typically years following exposure
Nausea is associated with the (hematologic/prodomal) syndrome.
prodomal. Symptoms of the prodromal syndrome include nausea, vomiting, diarrhea, and anorexia
Radiation interacts with tissue (uniformly/randomly).
randomly. The effects of radiation in tissue are a consequence of random interactions.
The (OER/RBE) describes the relative response to radiation in the presence or absence of oxygen.
OER. OER is the acronym for oxygen enhancement ratio. This ratio compares the effects of radiation in oxygenated tissue to hypoxic tissues
Cells are most sensitive during the (M,G2,S) phase of division.
M. The phase of mitosis is the most sensitive phase of cell division
The fraction of cells actually progressing through cycles of division is known as the (growth/surviving) fraction.
growth. During division, a portion of the cells are dividing causing growth of the tumor and another portion is dormant. The portion of cells dividing is known as the growth fraction
The period over which radiation is delivered is referred to as the (protraction/fractionation).
protraction. Protraction is the time over which radiation is delivered. Protraction is tracked by documenting elapsed days during the therapy regimen.
Erythematous skin reactions during fractionated radiation therapy are seen as a result of:
C. Erythema, or skin redness, is a result of vascular dilation
Epilation may initially be observed in patients receiving radiation under standard fractionation schemes at an approximate dose of:
A. Epilation, or hair loss, is typically observed after 15 Gy during standard fractionation (i.e. 2 Gy/day, 5 days/week)
The production of free radicals most often occurs from the irradiation of:
A. Free radicals are a result of the breaking of the chemical bond between hydrogen and oxygen molecules in water
Protracted or fractionated dose are better tolerated by tissue than single doses because:
A. Protracted or fractionated doses allow for the repair of normal tissue
Which of the following is an effect of radiation on DNA?
A. Cross-linking of broken segments of chromosomes are a consequence of DNA injury caused by radiation
As the dose of radiation increases:
A. The cumulative effect of radiation dose is the decreased ability for tissue to recover. This is desirable in the cancerous tissue and is demonstrated by increased severity of normal tissue injury as doses accumulate. Although normal tissue can recover more readily than cancerous tissue, more dose means longer delay in recovery
In linear or nonlinear threshold dose-response curves, the following is true of the response:
B. Threshold dose-response curves indicate that there is no overt response by exposed tissue below certain doses.
Radiation sickness symptoms associated with the reduced number of leukocytes is a major characteristic of:
B. Hematopoietic syndrome is caused by reduced blood cells. Leukocytes are most sensitive of blood cells are the first to show decrease leaving victims felling fatigued and vulnerable to deadly infections
The average energy deposited per unit of path length to a medium by ionizing radiation as it passes through that medium best describes:
A. LET or linear energy transfer is the energy deposited in an absorber as radiation passes through
The most radiosensitive tissue group among the following is the:
C. Compared to the others, the epithelial cells in the alimentary tract have a longer mitotic future and divide more often that mature central nervous and connective tissues found in muscle and cardiovascular systems
The four Rs of radiation biology are:
C. The four Rs include reoxygenation, repopulation, redistribution and repair
The whole body syndrome most likely to be observed follwoing a single dose of 1-10 Gy is the:
C. At this dose range, a decrease in peripheral blood cells and depression of the bone marrow is likely to occur
Which of the following would be a stochastic or late radiation response?
D. The development of radiation induced lung cancer would occur 10-20 years following exposure. A stochastic effect is one that occurs much later after initial exposure
Which of the following is a more accurate representation of cell radiosensitivity?
A. The Do value on the cell survival curve most accurately represents the sensitivity of certain cells to radiation. The smaller the Do, the more radiosensitive
The standard radiation used to determine RBE is:
C. RBE value compares a test radiation to 250 keV xrays
The central nervous system syndrome may be observed in those exposed to single whole body doses of:
D. The single whole body dose of 5000 cGy or greater, would likely cause the exposed to suffer from the CNS syndrome
Without medical intervention, a person exposed to a single whole body dose of ___ may die within 10 days.
A. Single whole body dose of about 10 Gy, or 1000 cGy would cause bone marrow suppression. Blood transfusion may rescue, but without this intervetion death would likely occur within 10 days
Normal tissue healing following radiation occurs by:
B. normal tissue may recover from radiation exposure by regeneration of cells or repair of cellular damage
Irradiation of the salivary glands may lead to permanent xerostomia above doses of ___using the typical 2 Gy per treatment, 5 treatments per week fractionation scheme.
B. High doses above 40 Gy may lead to permanent reduction in saliva
Exceeding the TD 50/5 for the spinal cord may lead to:
C. Beyond the tolerance of the spinal cord, there would likely be swelling and cell death
Tissue injury ___ as the volume of tissue irradiated increases.
A. The more volume exposed the greater the injury. A smaller proportion of cells are left to repair and repopulate damaged cells when a greater volume is exposed
