1) Which of the following statements is FALSE concerning the Arrhenius analysis of mammalian cell killing by heat?
A. This analysis suggests proteins as the likely targets for heat-induced cell killing.
B. The break point in the Arrhenius plot reflects the development of thermotolerance.
C. The Arrhenius relationship has been used to define the temperature dependence of the rate of heat-induced cell killing.
D. An Arrhenius curve plots the log of the slopes (1/Do) of heat survival curves as a function of temperature.
E. The break point in the Arrhenius plot occurs at approximately 39°C.
2) Hyperthermia combined with radiation may be effective in cancer therapy because:
A. tumor cells are intrinsically more sensitive to heat than normal cells.
B. hypoxic tumor cells, which may be at a low pH and nutritionally-deprived, exhibit enhanced sensitivity to heat.
C. heat increases the number of ionizations produced by a given dose of radiation.
D. normal tissues tend to retain more heat than tumors.
E. heat can produce maximum radiosensitization even if delivered several days after irradiation.
3) Which of the following statements concerning hyperthermia is TRUE?
A. Heat-induced radiosensitization occurs because heat produces additional DNA damage.
B. Hyperthermia transiently down-regulates genes that encode heat shock proteins.
C. Upon heating, the heat shock transcription factor, HSF1, stimulates production of heat shock proteins.
D. Heat shock proteins facilitate the aggregation of nuclear proteins.
E. Hyperthermia does not induce apoptotic cell death.
4) Which of the following statements concerning thermotolerance is TRUE?
A. Thermotolerance is a heritable resistance to heat-induced cell killing.
B. A brief exposure to a temperature above 43°C results in greater resistance to subsequent heat treatment at a lower temperature due to the development of thermotolerance (“step-down heating”).
C. Thermotolerance develops during the heating of tissues at temperatures higher than 43°C.
D. The onset and decay of thermotolerance correlate with the appearance and disappearance of proteins associated with the repair of heat-induced DNA strand breaks.
E. Heat shock proteins are molecular chaperones.
5) Which of the following statements concerning possible long-term consequences of radiotherapy is FALSE?
A. Because IMRT reduces the total dose received by normal tissues, the risk of second malignancies should also be reduced.
B. Compared to the general population, individuals who survive an initial cancer are at an increased risk for developing a second cancer.
C. There is an increased incidence of second tumors among patients initially treated for soft tissue sarcomas.
D. Radiotherapy to the breast or chest wall of young women is associated with long-term cardiotoxicity and an increased risk of second breast cancers.
6) In children, which of the following organs is the most sensitive to the induction of both benign and malignant tumors by X-rays?
A. bone marrow
B. intestine
C. breast
D. thyroid
E. lung
7) Among those who develop fatal cancers after total body irradiation, approximately what percentage are leukemias?
A. 0.1%
B. 2%
C. 15%
D. 40%
E. 80%
8) For children epilated by X-rays for the treatment of tinea capitis, which of the following organs did NOT demonstrate an excess relative risk for a radiation-induced malignancy?
A. brain
B. thyroid
C. pharynx
D. bone marrow
9) Cancers induced in humans by acute, whole-body irradiation with low total doses:
A. include excess breast cancers in female radium dial painters
B. can be distinguished from those occurring naturally
C. clearly follow a linear, no-threshold (LNT) dose response
D. exhibit similar latency periods for both leukemias and solid tumors
E. are more likely to appear in individuals who were young at the time of irradiation
10) Which of the following statements concerning radiation-induced effects among survivors of the atomic bombings of Hiroshima and Nagasaki is CORRECT?
A. There is little or no evidence for an increase in heart disease among survivors who received less than 5 Gy.
B. Susceptibility to radiation-induced breast cancer increases with increasing age at the time of exposure.
C. The latency period between irradiation and the appearance of most solid tumors is 1-3 years.
D. Statistically significant increases in mortality from non-cancer causes with increasing dose have been observed.
E. For a population of 1,000 people, each exposed to an acute, whole body dose of 1 Sv, roughly 8 would die from a radiation-induced cancer.
11) Which of the following biological effects has been noted in the children of cancer survivors treated with radiotherapy?
A. An excess incidence of low birth weight and premature birth have been reported among the offspring of female radiotherapy patients.
B. A lower average IQ has been measured in the children of patients irradiated for cranial tumors.
C. For patients treated with whole body irradiation, offspring show decreased height and weight at birth.
D. The children of patients treated for gastrointestinal cancers show an increased incidence of hepatic tumors.
E. More neonatal complications occur among children whose fathers received radiotherapy.
12) Which of the following is NOT a general conclusion of epidemiological studies of irradiated human populations?
A. Most regulatory and advisory committees recommend that risk estimates derived from acute exposures be reduced by a Dose and Dose-Rate Effectiveness Factor (DDREF) of approximately 2.0 in order to apply them to chronic, low dose and low dose-rate exposures.
B. Analyses of the Japanese A-bomb survivor data indicate that radiation risk is dependent on age at exposure, time since exposure, and gender.
C. For solid tumors in A-bomb survivors, a linear-quadratic fit to the data is significantly better than a linear fit.
D. Studies of populations living near nuclear power plants, or of populations exposed to elevated background radiation, usually do not provide a direct quantitative estimate of risk.
E. Based on the BEIR VII estimates, human exposure to ionizing radiation accounts for a relatively small lifetime excess cancer risk, estimated at about 1% per 100 mSv.
13) Patients exposed to ionizing radiation for imaging or therapy serve as valuable populations for the study of radiation-induced carcinogenesis. All of the following statements are true concerning these populations, EXCEPT:
A. Prenatal X-rays were first associated with an increased risk of childhood leukemia and cancer in the 1950s in a UK-wide study called the Oxford Survey of Childhood Cancers (OSCC).
B. Studies of populations who received diagnostic radiation exposures are, in principle, more suited than populations who received therapeutic exposures, for the evaluation of health risks following low doses of radiation.
C. Based on studies of the offspring of irradiated mothers, a prenatal dose of 1-2 cGy is sufficient to cause a statistically significant increase in radiation-induced cancer.
D. The carcinogenic effects of radiation exposure in utero and in childhood are similar because the cells that give rise to most childhood cancers persist and are proliferative for many years after birth.
E. An excess relative risk of 50 per Gy, and an excess absolute risk of 8% per Gy, have been reported for childhood cancer caused by prenatal irradiation.
14) The genetically significant dose (GSD) is:
A. of particular concern with respect to radon inhalation
B. approximately 1 Sv and corresponds to the average annual dose received from all medical procedures involving ionizing radiation performed in the US
C. the annual average gonadal dose to a population adjusted for the relative child expectancy of that population
D. an estimate of the number of children born each year with a radiation-induced mutation
E. the extrapolated lifetime gonadal dose for an individual
15) Which one of the following statements is CORRECT concerning radiation mutagenesis?
A. Radiation produces unique mutations not otherwise seen spontaneously.
B. It has been reported that children of radiotherapy patients have an increased incidence of genetic abnormalities compared to children whose parents had not been irradiated prior to conception.
C. Roughly 25% of the spontaneous mutations in humans can be attributed to exposure to background radiation.
D. The genetic doubling dose for humans has been estimated at 1-2 Sv.
E. The absolute mutation rate in humans is approximately 8% per Sv.
16) Which of the following statements is FALSE regarding studies of the Japanese A-bomb survivors by the Radiation Effects Research Foundation (RERF)?
A. More than 40% of the survivor cohort are still alive today.
B. Significantly more mutations are noted in children born to parents where one or both had been irradiated, and these data form the basis for the genetic doubling dose estimate for humans.
C. More than 60% of the survivor cohort received acute exposures less than 100 mSv.
D. One strength of the RERF Life Span Study is that robust dose estimates are available for the survivors, based on a dosimetry model called DS02.
E. A cohort of survivors, called the Adult Health Study, receive thorough clinical examinations every two years.
17) Which of the following statements concerning the landmark “mega-mouse” study of radiation mutagenesis, is INCORRECT?
A. The dose response curve for radiation-induced mutations was linear with no threshold.
B. Radiation dose-rate was not found to affect the induction of mutations.
C. Males were more susceptible to radiation-induced mutations than females.
D. Mutation rates at the different loci studied varied widely.
E. The estimated doubling dose for mutations was approximately 1 Gy.
