(a) What are the mechanisms of radiation damage?
(b) Does the direct action or indirect action contribute more to
radiation damage? Why?
(c) Which are the free radicals that are most damaging to cells?
(d) Does the presence of oxygen increase or decrease radiation
damage?
(a) Why are erythroblasts more radiosensitive than red blood cells?
(b) Which phase of the cell cycle is most radiosensitive?
(c) Which molecule of the cell structure is most radiosensitive?
(d) What are the different factors affecting radiation damage?
(a) Define D 0 ,Dq, and nas illustrated in the cell survival curve.
(b)Dqis smaller for high-LET radiations than for low-LET radiations.
True or false?
(c)D 0 is smaller for high-LET radiations than for low-LET radiations.
True or false?
(d) What is the value of nfor mammalian cells?
(a) The cell survival curve is steeper at high radiation doses than at
low radiation doses. Explain why and its implication.
(b) Does the shape of the cell survival curve vary with high-LET
radiations and at very high-dose rates?
(a) Choose the dose in rad that has been suggested as a practical
threshold for radiation-induced abortion: (i) 2; (ii) 5; (iii) 10; (iv)
20; (v) 50.
(b) How many days after conception can prenatal death occur as a
result of in utero irradiation?
(c) Which one of the following organs is most affected to be mal-
formed by prenatal radiation exposure? (i) heart; (ii) stomach; (iii)
head; (iv) gonads; (v) upper extremities.
(d) What is the period of pregnancy during which the incidence of
abnormalities and malformations in human neonates is expected
to be the highest?
(e) What are the effects of radiation on the fetus?
(f) The incidence of childhood leukemia after in utero irradiation with
a few rad of diagnostic x-rays increases by a factor of (i) 1.5–2.0;
(ii) 2.5–3.0; (iii) 3.5–6.0.
(a) What are the dose ranges and approximate time limits of death for
hemopoietic, gastrointestinal, and cerebrovascular syndromes?
(b) What are the prodromal syndromes and when do they appear?
(c) What is the dose at which almost total immunosuppression occurs
in humans?
(a) Define the oxygen enhancement ratio (OER).
(b) Why is the oxygen effect absent for high-LET radiations?
(c) What are radiosensitizers? Name some of them.
