RT Radiation Biology

Question 1

Which of the following correctly lists the 4 R's of radiobiology?

Accepted Answer

Repair, Reoxygenation, Redistribution, Repopulation

Answer

Reduction, Resistance, Regeneration, Recovery

Answer

Repair, Reduction, Reoxygenation, Resistance

Answer

Redistribution, Resistance, Recovery, Repopulation

Question 2

Which phase of the cell cycle is considered MOST radiosensitive?

Accepted Answer

M phase (mitosis)

Answer

Late S phase

Answer

G1 phase

Answer

Early S phase

Question 3

What is the oxygen enhancement ratio (OER) for high-LET radiation such as fast neutrons?

Accepted Answer

Approximately 1.0 (no oxygen enhancement)

Answer

Approximately 2.5–3.0

Answer

Approximately 1.5

Answer

Approximately 3.5

Question 4

What is the primary purpose of the linear-quadratic (LQ) model in radiation therapy?

Accepted Answer

Predicting cell survival and comparing fractionation schedules

Answer

Calculating tumor volume from imaging

Answer

Measuring radiation output from a linac

Answer

Determining beam energy selection

Question 5

Which cell cycle phase is considered MOST radioresistant?

Accepted Answer

Late S phase

Answer

M phase

Answer

G2 phase

Answer

G1 phase

Question 6

What does the alpha/beta ratio describe in radiobiology?

Accepted Answer

The fractionation sensitivity of tissues and tumors

Answer

The ratio of high-LET to low-LET radiation used in treatment

Answer

The oxygen enhancement ratio for a given tissue

Answer

The relative biological effectiveness of a radiation type

Question 7

Which type of ionizing radiation has the HIGHEST linear energy transfer (LET)?

Accepted Answer

Alpha particles

Answer

X-rays (photons)

Answer

Electrons

Answer

Gamma rays