Radiation Biology Exam 1 Prep Questions with
Accurate Answers Graded A+ (2024/2025)
Dividing the radiation doses into split fractions has less effect on cell survival for
neutrons (high LET) compared to photon radiation
True or False - ✔️✔️True
What is the recommended time required between radiation doses in order to allow for
reassortment of the cell population to enter a new radiosensitive cell phase?
4 hours
24 hours
6 hours
2 hours - ✔️✔️6 hours
Which stage of mitosis is most variable amongst mammalian cells?
G1
G2
S
Z - ✔️✔️G1
Which cell cycle stage is OER highest in?
G1
S
G2
Z - ✔️✔️S
What is the prominent HDR source used today?
Iridium-192
Cesium-137
Iodine-125
Iodine-131 - ✔️✔️Iridium-192
A decrease in dose rate has decreased cell survival
True or False - ✔️✔️False
An increase in dose rate for Iridium-192 HDR applications improves local recurrence
rates
True or False - ✔️✔️True
Fractionated doses allow for better repair for multiple-track damage
True or False - ✔️✔️True
Which phase of the cell cycle is most resistant?
, G1
S
G2
M - ✔️✔️S
Which phase of the cell cycle is associated with the molecular checkpoint gene? -
✔️✔️G2
Which of the following categories of mammalian cells is the most radioresistant?
Differentiating Intermitotic Cells
Vegetative Intermitotic Cells
Reverting Postmitotic Cells
Fixed Postmitotic Cells - ✔️✔️Fixed Postmitotic Cells
What was the distance for oxygen diffusion discovered by Thomlinson and Gray in their
research?
10 micrometers
300 micrometers
50 micrometers
150 micrometers - ✔️✔️150 micrometers
What is the reasoning for fractionating radiation doses for a tumor in order to exploit
differential cell killing with hypoxic/oxic cells?
Reassortment
Repair
Reoxygenation
Repopulation - ✔️✔️Reoxygenation
Which of the following radiation types has the highest LET?
Alpha Particles
Protons
Gamma Rays
X-Rays - ✔️✔️Alpha Particles
Which of the following radiation types would the oxygen enhancement effect be greatest
for?
Protons
Alpha Particles
Neutrons
Gamma Rays - ✔️✔️Gamma Rays
Which term explains how free radicals can be more easily repaired under hypoxia but
may be made more permanent with oxygenation?
Oxygen Fixation Hypothesis
Relative Biologic Effectiveness
Accurate Answers Graded A+ (2024/2025)
Dividing the radiation doses into split fractions has less effect on cell survival for
neutrons (high LET) compared to photon radiation
True or False - ✔️✔️True
What is the recommended time required between radiation doses in order to allow for
reassortment of the cell population to enter a new radiosensitive cell phase?
4 hours
24 hours
6 hours
2 hours - ✔️✔️6 hours
Which stage of mitosis is most variable amongst mammalian cells?
G1
G2
S
Z - ✔️✔️G1
Which cell cycle stage is OER highest in?
G1
S
G2
Z - ✔️✔️S
What is the prominent HDR source used today?
Iridium-192
Cesium-137
Iodine-125
Iodine-131 - ✔️✔️Iridium-192
A decrease in dose rate has decreased cell survival
True or False - ✔️✔️False
An increase in dose rate for Iridium-192 HDR applications improves local recurrence
rates
True or False - ✔️✔️True
Fractionated doses allow for better repair for multiple-track damage
True or False - ✔️✔️True
Which phase of the cell cycle is most resistant?
, G1
S
G2
M - ✔️✔️S
Which phase of the cell cycle is associated with the molecular checkpoint gene? -
✔️✔️G2
Which of the following categories of mammalian cells is the most radioresistant?
Differentiating Intermitotic Cells
Vegetative Intermitotic Cells
Reverting Postmitotic Cells
Fixed Postmitotic Cells - ✔️✔️Fixed Postmitotic Cells
What was the distance for oxygen diffusion discovered by Thomlinson and Gray in their
research?
10 micrometers
300 micrometers
50 micrometers
150 micrometers - ✔️✔️150 micrometers
What is the reasoning for fractionating radiation doses for a tumor in order to exploit
differential cell killing with hypoxic/oxic cells?
Reassortment
Repair
Reoxygenation
Repopulation - ✔️✔️Reoxygenation
Which of the following radiation types has the highest LET?
Alpha Particles
Protons
Gamma Rays
X-Rays - ✔️✔️Alpha Particles
Which of the following radiation types would the oxygen enhancement effect be greatest
for?
Protons
Alpha Particles
Neutrons
Gamma Rays - ✔️✔️Gamma Rays
Which term explains how free radicals can be more easily repaired under hypoxia but
may be made more permanent with oxygenation?
Oxygen Fixation Hypothesis
Relative Biologic Effectiveness
