RADIATION BIOLOGY COMPREHENSIVE EXAM
2026/2027 QUESTIONS AND SOLUTIONS RATED A+
✔✔What are non-stochastic effects? - ✔✔Deterministic somatic effects directly related
to the dose received.
✔✔ What are acutely responding tissues? - ✔✔Rapidly dividing cells that show injury
after a short period of time.
✔✔What are late responding tissues? - ✔✔Slowly dividing cell populations that show
injury after at least 3 months post-irradiation.
✔✔What are acute effects of radiation? - ✔✔First effects seen, can be reversible or
irreversible, examples include pneumonitis and esophagitis.
✔✔What are chronic effects of radiation? - ✔✔Irreversible and permanent effects due to
depletion of critical nonparenchymal cells.
✔✔What is a primary chronic effect? - ✔✔Due to the depletion of critical
nonparenchymal cells.
✔✔What is a secondary chronic effect? - ✔✔A consequence of irreversible and
consequently progressive acute effect.
✔✔What is regeneration in the context of radiation? - ✔✔Replacement of damaged
cells in the organ by the same cell type.
✔✔What is repair in the context of radiation? - ✔✔Replacement of original cell by
different cell type.
✔✔What are the two clinical factors that influence radiation response? - ✔✔Dose and
volume.
✔✔What is a fractionated dose? - ✔✔Dose divided into different time slots.
✔✔What is an acute change in radiation effects? - ✔✔Examples include inflammation,
edema, and hemorrhage.
✔✔What is a chronic change in radiation effects? - ✔✔Examples include ulceration,
obstruction, and necrosis.
✔✔Why are circulating blood cells considered radioresistant? - ✔✔They are non-
dividing and mature; exception is lymphocytes.
, ✔✔What reflects bone marrow damage in circulating blood? - ✔✔Sensitivity of the
different stem cells and lifespan of each cell type.
✔✔What are the effects of decreased platelets? - ✔✔Decreased ability to clot.
✔✔What are the effects of decreased RBCs? - ✔✔Anemia.
✔✔What are the effects of decreased WBCs? - ✔✔Decreased ability to fight infection.
✔✔List the radiation sensitivity of cells from most sensitive to least sensitive. - ✔✔1.
Lymphocytes, 2. Granulocytes, 3. Platelets, 4. Erythrocytes.
✔✔What are acute changes caused by irradiation of the skin? - ✔✔Inflammation, dry or
moist desquamation, erythema.
✔✔What is maturation depletion? - ✔✔Depletion of mature sperm.
✔✔How does radiation affect male fertility? - ✔✔Causes maturation depletion of mature
sperm; temporary sterility at 2.5 Gy, permanent sterility at 5-6 Gy.
✔✔What dose of radiation produces sterility in women? - ✔✔6.25 Gy (625 rads)
produces sterility.
✔✔What pathology is produced by a collection of dead cells within the eye? -
✔✔Cataracts; 100% of the population develops this at 7 Gy.
✔✔What effect may be observed after irradiation of blood vessels? - ✔✔Occlusion of
small vessels can lead to loss of nutrients and oxygen.
✔✔What are the results of high doses of radiation delivered to the heart? -
✔✔Pericarditis and pancarditis.
✔✔What does a moderate dose of radiation produce in growing bone and cartilage? -
✔✔Temporary delay of mitosis and death of immature cells.
✔✔What does a high dose of radiation produce in growing bone and cartilage? -
✔✔May result in no more bone formation.
✔✔Why is the liver considered a moderately radiosensitive organ? - ✔✔Due to large
blood supply.
✔✔What changes may be observed after irradiation of the urinary system? - ✔✔Loss of
tubules, kidney becomes atrophic, renal failure.
2026/2027 QUESTIONS AND SOLUTIONS RATED A+
✔✔What are non-stochastic effects? - ✔✔Deterministic somatic effects directly related
to the dose received.
✔✔ What are acutely responding tissues? - ✔✔Rapidly dividing cells that show injury
after a short period of time.
✔✔What are late responding tissues? - ✔✔Slowly dividing cell populations that show
injury after at least 3 months post-irradiation.
✔✔What are acute effects of radiation? - ✔✔First effects seen, can be reversible or
irreversible, examples include pneumonitis and esophagitis.
✔✔What are chronic effects of radiation? - ✔✔Irreversible and permanent effects due to
depletion of critical nonparenchymal cells.
✔✔What is a primary chronic effect? - ✔✔Due to the depletion of critical
nonparenchymal cells.
✔✔What is a secondary chronic effect? - ✔✔A consequence of irreversible and
consequently progressive acute effect.
✔✔What is regeneration in the context of radiation? - ✔✔Replacement of damaged
cells in the organ by the same cell type.
✔✔What is repair in the context of radiation? - ✔✔Replacement of original cell by
different cell type.
✔✔What are the two clinical factors that influence radiation response? - ✔✔Dose and
volume.
✔✔What is a fractionated dose? - ✔✔Dose divided into different time slots.
✔✔What is an acute change in radiation effects? - ✔✔Examples include inflammation,
edema, and hemorrhage.
✔✔What is a chronic change in radiation effects? - ✔✔Examples include ulceration,
obstruction, and necrosis.
✔✔Why are circulating blood cells considered radioresistant? - ✔✔They are non-
dividing and mature; exception is lymphocytes.
, ✔✔What reflects bone marrow damage in circulating blood? - ✔✔Sensitivity of the
different stem cells and lifespan of each cell type.
✔✔What are the effects of decreased platelets? - ✔✔Decreased ability to clot.
✔✔What are the effects of decreased RBCs? - ✔✔Anemia.
✔✔What are the effects of decreased WBCs? - ✔✔Decreased ability to fight infection.
✔✔List the radiation sensitivity of cells from most sensitive to least sensitive. - ✔✔1.
Lymphocytes, 2. Granulocytes, 3. Platelets, 4. Erythrocytes.
✔✔What are acute changes caused by irradiation of the skin? - ✔✔Inflammation, dry or
moist desquamation, erythema.
✔✔What is maturation depletion? - ✔✔Depletion of mature sperm.
✔✔How does radiation affect male fertility? - ✔✔Causes maturation depletion of mature
sperm; temporary sterility at 2.5 Gy, permanent sterility at 5-6 Gy.
✔✔What dose of radiation produces sterility in women? - ✔✔6.25 Gy (625 rads)
produces sterility.
✔✔What pathology is produced by a collection of dead cells within the eye? -
✔✔Cataracts; 100% of the population develops this at 7 Gy.
✔✔What effect may be observed after irradiation of blood vessels? - ✔✔Occlusion of
small vessels can lead to loss of nutrients and oxygen.
✔✔What are the results of high doses of radiation delivered to the heart? -
✔✔Pericarditis and pancarditis.
✔✔What does a moderate dose of radiation produce in growing bone and cartilage? -
✔✔Temporary delay of mitosis and death of immature cells.
✔✔What does a high dose of radiation produce in growing bone and cartilage? -
✔✔May result in no more bone formation.
✔✔Why is the liver considered a moderately radiosensitive organ? - ✔✔Due to large
blood supply.
✔✔What changes may be observed after irradiation of the urinary system? - ✔✔Loss of
tubules, kidney becomes atrophic, renal failure.
