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Radiation Physics and Radiobiology Flashcards

7 cards from real ARRT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Radiation Physics and Radiobiology flashcards as text

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

    Answer: Alpha particles

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

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

    Answer: Comparing tumor hypoxia sensitivity to radiation

    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.

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

    Answer: Compton scattering

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

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

    Answer: Gray

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

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

    Answer: Beta-minus decay

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

  6. What is the primary mechanism by which ionizing radiation damages DNA indirectly?

    Answer: Free radical formation from water radiolysis

    Indirect DNA damage occurs when radiation ionizes water molecules, producing hydroxyl radicals (·OH) that then attack and break DNA strands.

  7. Which of the following best describes the inverse square law?

    Answer: Intensity decreases by a factor of four when distance doubles

    The inverse square law states that radiation intensity is inversely proportional to the square of the distance, so doubling distance reduces intensity to one-quarter.