ARRT Radiation Physics and Radiobiology Practice Questions
Safety · 21 of the 200 scored questions in ARRT’s content specifications
230 questions across all eight subcategories in 230 minutes, with a score for Physics and Radiobiology so you know where you stand.
Free Physics and Radiobiology drillWhy does bone attenuate x-rays more than soft tissue?
Radiation Physics and Radiobiology on the ARRT radiography exam
Radiation Physics and Radiobiology has 21 of the 200 scored questions, part of the Safety category. It covers how the x-ray tube makes x-rays, what controls the energy and number of photons, how photons interact with the body, the SI units ARRT uses, and how radiation damages cells and tissues.
- Share of the exam
- 21 of the 200 scored questions now; 21 from March 1, 2027
- Our drill
- 10 questions from 50 Physics and Radiobiology questions, untimed, an explanation after every answer; one free attempt, unlimited with a pass
What Radiation Physics and Radiobiology questions test
- X-ray production: thermionic emission, acceleration across the tube, and deceleration at the anode
- Target interactions: bremsstrahlung and characteristic radiation, and how kVp and target material change the spectrum
- Beam characteristics: quality and quantity, primary versus remnant radiation, wavelength and frequency, and the inverse square law
- Photon interactions: photoelectric absorption, Compton scatter and coherent scatter, and attenuation by tissue thickness and atomic number
- SI units (NCRP Report No. 160): gray, sievert, coulomb per kilogram and air kerma
- Radiobiology: dose-response curves, LET and RBE, the law of Bergonié and Tribondeau, the oxygen effect, deterministic versus stochastic effects, fetal risk and the acute radiation syndromes
Sit the full exam under the real clock
230 questions across all eight subcategories in 230 minutes, with a score for Physics and Radiobiology so you know where you stand.
Free Physics and Radiobiology drillHow to study it
- Work inverse square law problems until they take under a minute: intensity changes with the square of the distance ratio.
- Remember the two interaction rules: photoelectric absorption makes contrast and patient dose; Compton scatter makes fog and occupational dose.
- Learn which cells are most radiosensitive (lymphocytes, spermatogonia, stem cells) and which are least (nerve and muscle cells).
- Take the physics and radiobiology drill until you score 80% or better.
Common questions
Does the ARRT radiography exam use SI units?
Yes. ARRT’s content specifications say SI units are the primary units of radiation measurement on the radiography exam: gray for absorbed dose and air kerma, sievert for equivalent and effective dose, and coulomb per kilogram for exposure.
How many physics questions are on the ARRT radiography exam?
Radiation Physics and Radiobiology has 21 scored questions, under both the current specifications and the specifications effective March 1, 2027.
230 questions across all eight subcategories in 230 minutes, with a score for Physics and Radiobiology so you know where you stand.
Free Physics and Radiobiology drillThe other ARRT radiography content areas
Sources
- ARRT: Radiography Examination Content Specifications, in force through February 28, 2027 (PDF)
- ARRT: Radiography Examination Content Specifications, effective March 1, 2027 (PDF)
- ARRT: 2026 Primary Eligibility Pathway Handbook: exam format, scoring, exam window and attempts (PDF)
- ARRT: Fees
- ARRT: Annual Exam Report 2025: passing score and approximate percent correct (PDF)
- ARRT: Updated Radiography documents (May 1, 2026), changes effective March 1, 2027
- NCRP Report No. 116, Limitation of Exposure to Ionizing Radiation
Original practice questions for exam preparation, written to the ARRT Radiography Examination Content Specifications, not ARRT exam questions. Independent practice, not affiliated with or endorsed by The American Registry of Radiologic Technologists (ARRT) or Pearson VUE. ARRT and R.T. are trademarks of the ARRT.