ARRT Radiation Physics and Radiobiology 2

Question 1

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

Accepted Answer

Alpha particles

Answer

Alpha particles have the highest LET because they are heavy, doubly charged particles that deposit energy very densely over a short range.

Question 2

The oxygen enhancement ratio (OER) is MOST relevant in which radiobiological context?

Accepted Answer

Comparing tumor hypoxia sensitivity to radiation

Answer

OER quantifies how much more radiation dose is needed to achieve the same cell kill in hypoxic versus well-oxygenated conditions, directly relevant to tumor radiobiology.

Question 3

Which interaction predominates when a 100 keV photon passes through soft tissue?

Accepted Answer

Compton scattering

Answer

At 100 keV in soft tissue, Compton scattering predominates because this energy range is above the threshold for photoelectric dominance in low-Z materials.

Question 4

The unit of radiation absorbed dose in the SI system is:

Accepted Answer

Gray

Answer

The Gray (Gy) is the SI unit of absorbed dose, equal to 1 joule of energy deposited per kilogram of matter.

Question 5

Which radioactive decay mode results in the emission of an electron from the nucleus?

Accepted Answer

Beta-minus decay

Answer

Beta-minus decay occurs when a neutron converts to a proton, releasing an electron (beta particle) and an antineutrino from the nucleus.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Radiation Physics and Radiobiology 2