RSO Cheat Sheet 2026

The 30 highest-yield RSO facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which of the following is a required component of a Radiation Protection Program under NRC regulations? → Personnel dosimetry and exposure records
2. Which type of radiation has the greatest ionizing power but the least penetrating ability? → Alpha particles
3. If a worker suspects they have been contaminated with radioactive material, what should they do first? → Remove contaminated clothing and contain it
4. Secular equilibrium between a parent and daughter radionuclide occurs when: → The parent's half-life is much longer than the daughter's
5. The mean lethal dose (LD50/30) for humans from acute whole-body radiation exposure without medical treatment is approximately: → 4–5 Gy
6. A whole-body counter is used to measure: → Internally deposited gamma-emitting radionuclides
7. In the event of a radiation spill, what is the FIRST action that should be taken by the Radiation Safety Officer (RSO)? → Prevent access to the area and contain the spill
8. The specific activity of a radioactive material is defined as: → Activity per unit mass
9. Which of the following is a deterministic radiation effect? → Cataract of the eye lens
10. The tissue weighting factor (wT) for the gonads in ICRP Publication 103 is: → 0.08
11. NRC regulations require that a licensee notify the NRC Operations Center within 4 hours of discovering a radiation dose to an individual that: → Exceeds 25 rem (250 mSv) TEDE in 24 hours or other immediate notification thresholds
12. Which of the following best describes the role of the RSO in safety audits? → To manage only financial aspects of the radiation program
13. NRC regulations require that radiation safety training for workers be provided: → Before workers begin work in or frequenting restricted areas, and refreshed as necessary
14. Mixed waste contains both radioactive material and: → RCRA hazardous chemical waste
15. NRC Class A, B, and C classifications for LLRW are based primarily on: → The radionuclide content and concentration relative to NRC tables in 10 CFR 61.55
16. Which nuclear process results in the emission of a positron (β+)? → Beta-plus decay
17. When should a radiation worker wear their dosimeter at the collar level rather than at the waist? → When wearing a lead apron in fluoroscopy or other high-dose-rate x-ray environments
18. The inverse square law states that radiation intensity from a point source varies with distance by: → Decreasing proportionally to the square of the distance
19. A radiation emergency response plan for a nuclear medicine department must include all of the following EXCEPT: → A list of all workers' personal financial information
20. Internal dose assessment via bioassay is required when a worker's intake of radioactive material could result in a committed effective dose exceeding: → 10 mSv (1 rem)
21. What is the first step in responding to a radiation spill in a laboratory? → Evacuate personnel and prevent access to the area
22. Greater-than-Class-C (GTCC) LLRW differs from Class C in that it: → Cannot be disposed of in near-surface facilities and requires deep geological disposal
23. Which radiation-induced DNA lesion is considered the most biologically significant for cell killing and carcinogenesis? → Double-strand break
24. A personnel dosimeter reading must be investigated when it exceeds what percentage of the applicable dose limit according to NRC guidance? → 25%
25. An optically stimulated luminescence (OSL) dosimeter differs from a TLD primarily because it: → Releases stored dose information using light rather than heat
26. A radiation worker receives an equivalent dose of 50 mSv to the lens of the eye in one year. According to current ICRP guidance, this: → Exceeds the annual occupational lens dose limit of 20 mSv
27. Which statement correctly describes the relationship between photon energy and penetrating ability for X-rays and gamma rays? → Higher-energy photons are more penetrating
28. Which shielding material is most appropriate for attenuating high-energy gamma radiation in a radiology facility? → Lead or concrete
29. Low-level radioactive waste (LLRW) in the United States is regulated primarily under: → The Low-Level Radioactive Waste Policy Act and NRC 10 CFR Part 61
30. When fast neutrons are slowed down (moderated) to thermal energies, the process is primarily achieved by: → Elastic scattering collisions with light nuclei