FRCR Radiobiology 3

Question 1

Relative biological effectiveness (RBE) is defined as:

Accepted Answer

The ratio of a reference radiation dose to the test radiation dose required to produce the same biological effect

Answer

The ratio of biological damage in tumor versus normal tissue for the same radiation type

Answer

The ratio of high-LET to low-LET radiation damage

Answer

The ratio of absorbed dose to equivalent dose

Question 2

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

Accepted Answer

Alpha particles

Answer

Gamma rays

Answer

High-energy electrons

Answer

Fast neutrons

Question 3

Reoxygenation in tumors during fractionated radiotherapy refers to:

Accepted Answer

Movement of previously hypoxic tumor cells into better-oxygenated positions after irradiation kills oxic cells

Answer

Re-establishment of blood flow after vessel repair

Answer

Administration of supplemental oxygen during treatment sessions

Answer

Use of hyperbaric oxygen chambers to sensitize tumor cells

Question 4

Which of the following is NOT one of the classic '5 Rs' of radiobiology?

Accepted Answer

Regeneration

Answer

Repair

Answer

Reoxygenation

Answer

Redistribution

Question 5

The abscopal effect in radiotherapy refers to:

Accepted Answer

Tumor regression at sites distant from the irradiated field

Answer

Radiation-induced damage to shielded organs adjacent to the treatment field

Answer

Increased toxicity due to radiation scatter outside the treatment volume

Answer

Synergistic cell kill from combined chemoradiotherapy

Question 6

Which of the following is a clinically established radiosensitizer used concurrently with radiotherapy?

Accepted Answer

Cisplatin

Answer

Amifostine

Answer

Methotrexate

Answer

Bevacizumab

Question 7

Radiation-induced secondary malignancies arise primarily through which mechanism?

Accepted Answer

Induction of mutations in oncogenes or tumor suppressor genes in normal cells

Answer

Direct tumor cell kill triggering inflammatory carcinogenesis

Answer

Activation of carcinogenic viruses latent in irradiated normal tissues

Answer

Generation of reactive oxygen species that promote angiogenesis exclusively