Licensing Examination Practice

Illinois Radiation Therapy Technologist Licensing Examination Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of fractionation in radiation therapy?
• Reduce tumor oxygenation
• Allow normal tissues to repair between doses
• Increase tumor cell proliferation
• Deliver the total dose in a single session

Rationale: Fractionation allows normal tissues time to repair sub-lethal

damage while still effectively treating the tumor.

• Which of the following is the most radiosensitive phase of the cell

cycle?

• G1 phase 1 / 4

• S phase
• M phase
• G2 phase

Rationale: Cells are most sensitive to radiation during mitosis (M phase)

because DNA is highly condensed and vulnerable.

• What is the unit of absorbed radiation dose?
• Roentgen
• Curie
• Gray (Gy)
• Sievert

Rationale: Gray (Gy) measures absorbed dose, the amount of energy

deposited per kilogram of tissue.

• Which imaging modality is most commonly used for treatment

planning in external beam radiation therapy?

• Ultrasound

B. PET

• CT

D. MRI

Rationale: CT provides precise 3D anatomical information critical for

accurate radiation treatment planning.

• What is the main advantage of IMRT (Intensity-Modulated Radiation

Therapy) over conventional 3D-CRT? 2 / 4

• Shorter treatment times
• Less precise dose distribution
• Ability to deliver conformal doses while sparing normal tissue
• Uses lower energy photons

Rationale: IMRT allows dose modulation to conform tightly to tumor shape

while minimizing exposure to surrounding normal tissues.

6. The half-life of a radioactive isotope is:

• The time it takes for the isotope to decay completely
• The time it takes for half of the isotope to decay
• The time it takes to deliver a therapeutic dose
• The time it takes for the isotope to double in activity

Rationale: Half-life is the period during which half of the radioactive atoms

decay.

• In linear accelerator radiation therapy, which component shapes the

treatment field?

• Gantry
• Multi-leaf collimator (MLC)
• Waveguide
• Bending magnet

Rationale: MLCs consist of movable leaves that shape the radiation beam

to match the tumor's contour. 3 / 4

• Which type of radiation has the highest linear energy transfer (LET)?
• X-rays
• Gamma rays
• Alpha particles
• Beta particles

Rationale: Alpha particles deposit more energy per unit distance (high LET)

compared to photons and beta particles.

• What is the standard daily dose for conventional fractionated external

beam radiation therapy?

• 5 Gy
• 1.8–2 Gy
• 3–4 Gy
• 0.5 Gy

Rationale: Standard fractionation delivers 1.8–2 Gy per day to balance

tumor control and normal tissue tolerance.

• Which of the following is a late-responding normal tissue effect?
• Skin erythema
• Nausea
• Fibrosis
• Hair loss

Rationale: Late-responding tissues, such as connective tissue, manifest

effects like fibrosis months or years after treatment.

• / 4