FRCR Radiobiology 2

Question 1

What is the standard dose per fraction in conventional radical radiotherapy?

Accepted Answer

1.8–2.0 Gy

Answer

1.2 Gy

Answer

3.0 Gy

Answer

5.0 Gy

Question 2

Which of the following best describes hyperfractionation in radiotherapy?

Accepted Answer

Multiple smaller fractions per day to increase total dose while limiting late toxicity

Answer

Fewer fractions with a higher dose per fraction

Answer

Treating 5 days per week with standard 2 Gy fractions

Answer

Compressing treatment into fewer weeks with the same dose per fraction

Question 3

A treatment delivers 2 Gy × 30 fractions to a tumor with α/β = 10 Gy. What is the Biologically Effective Dose (BED)?

Accepted Answer

72 Gy

Answer

60 Gy

Answer

80 Gy

Answer

90 Gy

Question 4

Accelerated repopulation of tumor cells during radiotherapy is generally thought to begin after approximately:

Accepted Answer

3–4 weeks

Answer

1 week

Answer

2 weeks

Answer

6–7 weeks

Question 5

Prostate cancer has an unusually low α/β ratio estimated at approximately:

Accepted Answer

1.5 Gy

Answer

10 Gy

Answer

5 Gy

Answer

8 Gy

Question 6

Stereotactic body radiotherapy (SBRT) is characterized by which fractionation schedule?

Accepted Answer

6–20 Gy × 3–5 fractions

Answer

1.8–2 Gy × 25–30 fractions

Answer

1.2 Gy × 2 fractions per day

Answer

2 Gy × 15 fractions

Question 7

Which statement correctly compares late-responding and early-responding tissues in fractionated radiotherapy?

Accepted Answer

Late-responding tissues have lower α/β ratios and are more sensitive to high doses per fraction

Answer

Late-responding tissues have higher α/β ratios and are more sensitive to high doses per fraction

Answer

Early-responding tissues have lower α/β ratios and tolerate large fractions well

Answer

Both tissue types respond equally to changes in dose per fraction