TEXAS RADIATION THERAPIST LICENSE
EXAM PRACTICE EXAM QUESTIONS AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
| INSTANT DOWNLOAD PDF
1. Which interaction of x-rays with matter is dominant in
radiation therapy megavoltage beams?
A. Photoelectric effect
B. Coherent scattering
C. Compton scattering
D. Pair production
Rationale: Megavoltage beams primarily interact through
Compton scattering due to energy range and tissue electron
density.
2. The SI unit of absorbed dose is:
A. Roentgen
B. Curie
C. Gray
,D. Sievert
Rationale: The Gray (Gy) is the SI unit representing absorbed
dose in joules per kilogram.
3. Which organ is the most radiosensitive?
A. Heart
B. Kidney
C. Liver
D. Bone marrow
Rationale: Bone marrow contains rapidly dividing stem cells,
making it highly radiosensitive.
4. The term “Dmax” refers to:
A. Maximum field size
B. Depth of maximum dose
C. Maximum dose rate
D. Machine output
Rationale: Dmax is the depth at which the therapeutic beam
delivers its maximum absorbed dose.
5. Which modality uses high-energy photons generated
through Bremsstrahlung?
,A. Brachytherapy
B. Linear accelerator (LINAC)
C. Proton therapy
D. Gamma knife
Rationale: LINACs create high-energy photons via
Bremsstrahlung from high-speed electrons hitting a target.
6. The purpose of multileaf collimators (MLCs) is to:
A. Produce electron beams
B. Shape the radiation field
C. Monitor dose rate
D. Increase SSD
Rationale: MLCs shape fields to conform dose to tumor volume
while sparing normal tissue.
7. 3D-CRT planning requires:
A. Fluoroscopy
B. MRI only
C. CT simulation
D. Ultrasound
Rationale: CT imaging provides electron density and
anatomical data required for 3D dose calculation.
, 8. Hypofractionation refers to:
A. Smaller dose per fraction
B. More fractions per day
C. Larger dose per fraction
D. Two-week treatment
Rationale: Hypofractionation involves fewer treatment days
with larger individual fraction doses.
9. A Geiger-Mueller counter is primarily used for:
A. Photon calibration
B. Radiation area monitoring
C. Dose output testing
D. Patient imaging
Rationale: GM counters are sensitive detectors for
contamination and environmental radiation.
10. The tolerance dose (TD 5/5) for spinal cord is
approximately:
A. 10 Gy
B. 20 Gy
C. 45–50 Gy
D. 70 Gy
EXAM PRACTICE EXAM QUESTIONS AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
| INSTANT DOWNLOAD PDF
1. Which interaction of x-rays with matter is dominant in
radiation therapy megavoltage beams?
A. Photoelectric effect
B. Coherent scattering
C. Compton scattering
D. Pair production
Rationale: Megavoltage beams primarily interact through
Compton scattering due to energy range and tissue electron
density.
2. The SI unit of absorbed dose is:
A. Roentgen
B. Curie
C. Gray
,D. Sievert
Rationale: The Gray (Gy) is the SI unit representing absorbed
dose in joules per kilogram.
3. Which organ is the most radiosensitive?
A. Heart
B. Kidney
C. Liver
D. Bone marrow
Rationale: Bone marrow contains rapidly dividing stem cells,
making it highly radiosensitive.
4. The term “Dmax” refers to:
A. Maximum field size
B. Depth of maximum dose
C. Maximum dose rate
D. Machine output
Rationale: Dmax is the depth at which the therapeutic beam
delivers its maximum absorbed dose.
5. Which modality uses high-energy photons generated
through Bremsstrahlung?
,A. Brachytherapy
B. Linear accelerator (LINAC)
C. Proton therapy
D. Gamma knife
Rationale: LINACs create high-energy photons via
Bremsstrahlung from high-speed electrons hitting a target.
6. The purpose of multileaf collimators (MLCs) is to:
A. Produce electron beams
B. Shape the radiation field
C. Monitor dose rate
D. Increase SSD
Rationale: MLCs shape fields to conform dose to tumor volume
while sparing normal tissue.
7. 3D-CRT planning requires:
A. Fluoroscopy
B. MRI only
C. CT simulation
D. Ultrasound
Rationale: CT imaging provides electron density and
anatomical data required for 3D dose calculation.
, 8. Hypofractionation refers to:
A. Smaller dose per fraction
B. More fractions per day
C. Larger dose per fraction
D. Two-week treatment
Rationale: Hypofractionation involves fewer treatment days
with larger individual fraction doses.
9. A Geiger-Mueller counter is primarily used for:
A. Photon calibration
B. Radiation area monitoring
C. Dose output testing
D. Patient imaging
Rationale: GM counters are sensitive detectors for
contamination and environmental radiation.
10. The tolerance dose (TD 5/5) for spinal cord is
approximately:
A. 10 Gy
B. 20 Gy
C. 45–50 Gy
D. 70 Gy
