The Radiation Safety Officer Role: Duties, Authority, and Program Management

The Radiation Safety Officer (RSO) is the individual named on a radioactive material license who is responsible for implementing the facility's radiation protection program — and, just as importantly, the person the regulations vest with the authority to make it work.¹² Under 10 CFR 35.24, the RSO ensures that radiation safety activities are carried out in accordance with approved procedures and regulatory requirements, oversees the program day to day, keeps occupational and public exposures As Low As Reasonably Achievable (ALARA), investigates overexposures and medical events, and has the standing authority to stop unsafe operations.¹³

The role is defined by a tight cluster of regulations: 10 CFR 35.24 establishes the RSO's authority and responsibilities; 10 CFR 35.50 sets the training and experience required to qualify; 10 CFR 35.26 governs how the radiation protection program may change; and 10 CFR Part 20 supplies the dose limits, monitoring triggers, and ALARA framework the RSO administers.¹²³⁴ For broad-scope licensees, a Radiation Safety Committee adds an institutional layer of review. This guide explains what the RSO actually does, how a person qualifies for the role, how the program is structured and reviewed, and how the duties map to the specific Code of Federal Regulations sections an inspector will cite — for the technologists, physicists, and administrators who build and run these programs in Florida, Maryland, Virginia, Washington DC, California, and Nevada.

Introduction

A radiation protection program is only as strong as the authority behind it, and that authority is the Radiation Safety Officer. Every NRC or Agreement State medical-use license names a specific person as RSO, and that name is not a formality — it is a regulatory designation that carries defined duties, qualification requirements, and accountability.²⁵ When inspectors find that surveys lapsed, dosimetry went unreviewed, or a medical event was reported late, the finding almost always traces back to an RSO who lacked the time, resources, or delegated authority to run the program the license describes.⁶

The federal framework places medical use of byproduct material under 10 CFR Part 35, layered on the general radiation protection standards of 10 CFR Part 20.³⁴ Part 35 names the RSO and defines the role; Part 20 supplies the substance the RSO manages — the occupational dose limit of 5 rem (0.05 Sv) per year, the public limit of 0.1 rem (1 mSv) per year, the monitoring trigger at 10% of any limit, and the ALARA obligation that sits above all of them.⁴ Understanding the RSO role means understanding both: the authority granted by Part 35 and the program administered under Part 20. For the broader licensing context the RSO operates within, see our NRC radioactive material license guide.

Topic Explanation

The Radiation Safety Officer is a named, qualified individual with delegated authority over a facility's radiation protection program. The designation is specific to a license, and the duties are non-transferable in the sense that someone must hold them — the role cannot simply go vacant while licensed material is in use.

Key Terms

• Radiation Safety Officer (RSO): The individual identified on the license who is responsible for implementing the radiation protection program and who meets the training and experience criteria of 10 CFR 35.50.²⁵
• Associate Radiation Safety Officer (ARSO): An individual named on the license, qualified under 10 CFR 35.51, who oversees specific types of use under the RSO's overall direction.⁷
• Radiation protection program: The documented set of procedures, controls, surveys, training, recordkeeping, and reviews by which a licensee meets Part 20 and Part 35; 10 CFR 20.1101 requires it to be developed, documented, and implemented, with periodic content and implementation review.⁸
• ALARA: "As Low As Reasonably Achievable" — the principle, required under 10 CFR 20.1101(b), that exposures be kept below the regulatory limits to the extent reasonable, taking technology and economics into account.⁸
• Radiation Safety Committee (RSC): An institutional committee required for broad-scope (Type A) medical-use licensees that reviews and approves authorized users, the RSO, and significant program changes.⁹
• Authorized User (AU): A physician named on the license to direct specific medical uses of byproduct material; distinct from the RSO, who owns the safety program rather than directing clinical use.³

RSO Versus Authorized User Versus Medical Physicist

These three roles are routinely confused, and the distinction matters in an inspection. The RSO owns the radiation protection program — surveys, dosimetry, training, recordkeeping, ALARA, and event reporting. The Authorized User is the physician who directs clinical administrations of radioactive material within an authorized use category. The medical physicist (often the Authorized Medical Physicist, AMP, for certain uses) performs the equipment performance evaluations, calibrations, shielding reviews, and dosimetry calculations that support both. One person can sometimes hold more than one role — a qualified medical physicist frequently serves as RSO — but the responsibilities themselves remain distinct.

Key Technical Principles

The RSO role is best understood as a set of specific, citable duties paired with specific qualification routes. Both are spelled out in Part 35, and an effective program treats each duty as a scheduled, owned, documented obligation rather than an aspiration.

Core RSO Duties Mapped to Regulation and Cadence

The table below maps the principal RSO responsibilities to their controlling regulation and the typical frequency at which each is performed or reviewed. Frequencies marked "license-specified" depend on the conditions written into the individual license and the program's own procedures; confirm them against the license and the authority having jurisdiction.

Every line is a real, citable obligation, and the consistent pattern — visible in enforcement records — is that violations are usually timeliness or documentation failures on tasks the program was already supposed to perform.⁶ For the inspector's-eye view of where these break down, see our guide to common radiation safety violations.

RSO Qualification Pathways (10 CFR 35.50)

A person cannot simply be appointed RSO; they must meet the training and experience criteria of 10 CFR 35.50.² There are three principal routes, summarized below.

The 200-hour classroom and laboratory curriculum under 35.50(b) covers defined subject areas — radiation physics and instrumentation, radiation protection, mathematics pertaining to the use and measurement of radioactivity, radiation biology, and radiation dosimetry. The preceptor written attestation is the linchpin of the experience route: a current RSO who has supervised the candidate attests in writing that the individual has satisfactorily completed the requirements and is competent to function independently as an RSO for the types of use the license authorizes.² An Associate RSO (ARSO) is qualified under the parallel criteria of 10 CFR 35.51 and may be named to oversee specific use types under the RSO's overall direction.⁷

ALARA Investigational Levels — Worked

The RSO administers ALARA in practice through investigational levels — facility-set dose thresholds, below the regulatory limit, that trigger graded review before a worker ever approaches the limit. They are not themselves a regulatory limit; they are an ALARA management tool implemented under 10 CFR 20.1101(b), and they are conventionally tiered as Level I and Level II.⁸¹⁰

The reference point is the occupational annual limit in 10 CFR 20.1201: a total effective dose equivalent (TEDE) of 5 rem (0.05 Sv) per year.⁴ A common ALARA structure sets the investigational levels as fractions of that limit. Using the conventional 10%/30% structure from NRC ALARA program guidance, the monthly Level I and Level II thresholds are computed from the annual limit prorated to a month:¹⁰

A monthly badge result below Level I needs no individual action beyond routine logging. A result at or above Level I is noted and trended by the RSO; a result at or above Level II triggers a documented RSO investigation into why the dose occurred and what, if anything, should change.¹⁰ The specific percentages and the monthly-versus-quarterly basis are a program choice, not a fixed rule — many programs adopt the 10%/30% convention from NRC guidance, but the RSO sets and documents the actual levels in the ALARA program.

The same fraction-of-limit logic underlies the monitoring trigger itself. 10 CFR 20.1502 requires personnel monitoring when a worker is likely to receive more than 10% of any applicable limit in a year — i.e., more than 0.5 rem TEDE annually:⁴

That 0.5 rem figure is also the threshold at which the RSO's dose-record review takes on real weight: a worker trending toward it is a worker whose workload, technique, or shielding the RSO should be examining well before the annual limit is in play. For the mechanics of building and running that monitoring program, see our guide to occupational exposure monitoring programs.

The Radiation Safety Committee for Broad-Scope Licenses

Most medical-use licenses are limited- or standard-scope, and for these the RSO carries program responsibility without a mandatory committee. Broad-scope (Type A specific licenses of broad scope) licensees are different: they are required to establish a Radiation Safety Committee (RSC) to oversee the use of byproduct material.⁹ The RSC typically includes the RSO, an authorized user for each type of use permitted, a representative of management, and a representative of nursing or other affected staff. Its core functions are to review and approve (or disapprove) proposed authorized users, proposed RSO and ARSO designations, and significant changes to the radiation safety program, and to review the program — including the ALARA program and occupational dose trends — at least annually.⁹ Even where an RSC is not required, larger institutions often maintain one as a governance mechanism that distributes oversight and documents institutional commitment to radiation safety.

Clinical Impact

The RSO role is where regulatory compliance and patient and staff safety meet. A capable, empowered RSO is the difference between a program that is safe on paper and one that is safe in practice.

• It protects staff. By administering monitoring (10 CFR 20.1502), enforcing ALARA, and acting on investigational-level triggers, the RSO keeps occupational doses well below the 5 rem limit and identifies the technologist, cardiologist, or radiochemist whose dose trend signals a workflow or shielding problem.⁴⁸
• It protects patients. The RSO oversees the controls — dose-calibrator QC, written-directive verification, patient-release calculations — that prevent the administered-activity errors at the root of most medical events under 10 CFR 35.3045.³ When a medical event does occur, the RSO drives the investigation, the regulatory notification, and the corrective action.
• It protects the public and the license. Posting, surveys, source security, and waste decay-in-storage all flow through the RSO, and a lapse in any of them is both a public-safety gap and an enforcement exposure for the institution.⁶

The clinical stakes rise sharply in therapy programs. As radiopharmaceutical therapy expands, professional bodies have emphasized the central role of medical physics and robust radiation protection in delivering these treatments safely — the EFOMP policy statement on dosimetry in molecular radiotherapy, for example, stresses the responsibilities and inter-disciplinary collaboration needed to implement patient-specific dosimetry and protection as therapy moves from fixed activities toward individualized treatment.¹¹ Commissioning data from new facilities likewise show that a robust ALARA program is what keeps staff doses well below limits even in higher-activity environments such as on-site PET cyclotrons.¹²

Practical Tips

A strong RSO turns the duty table above into a running system. The highest-yield practices:

• Run a compliance calendar. Every dated obligation — daily dose-calibrator constancy, daily/weekly surveys, six-month leak tests and inventory, annual instrument calibration, annual training, and the annual program review — gets a due date, an owner, and a logged completion. A survey that is not logged did not happen, as far as an inspector is concerned.
• Document your authority. The single best predictor of a clean inspection is an RSO with protected time and written authority. Keep a signed delegation-of-authority memo and a current job description that mirror 10 CFR 35.24, and make sure management has formally granted the authority to stop unsafe operations.
• Set and use investigational levels. Write Level I and Level II into the ALARA program, review every badge cycle against them, and document the investigation whenever Level II is exceeded — that record is exactly what an inspector looks for.
• Verify the controls, don't assume them. Spot-check written directives before administrations, confirm posting matches measured dose rates, and watch the leak-test and inventory calendar — these generate findings out of proportion to their effort.
• Conduct a real annual program review. Under 10 CFR 20.1101(c), review both the content and the implementation of the program at least annually. Treat it as an internal audit with findings and corrective actions, not a signature on a form.
• Mock-inspect. Use the NRC or Agreement State inspection checklist and recent NRC Information Notices to surface issues while there is still time to fix them. Pair the RSO's program review with a qualified medical physicist's equipment evaluations and survey-meter calibrations so the safety data the program rests on is defensible.

Regulatory Considerations

The RSO role is defined by a compact set of regulations, and getting the jurisdiction right is itself part of the job:

• 10 CFR 35.24 — Authority and responsibilities for the radiation protection program. Names the RSO, requires the licensee to provide the authority, resources, and time to implement the program, and assigns the RSO responsibility for ensuring radiation safety activities follow approved procedures and for stopping unsafe operations.¹
• 10 CFR 35.50 / 35.51 — Training for the RSO and Associate RSO. Board certification, the 200-hour-plus-experience route with preceptor attestation, or qualification as an existing authorized individual.²⁷
• 10 CFR 35.26 — Radiation protection program changes. A licensee may make certain changes without prior NRC approval if the change is consistent with the regulations and license, is approved by the RSO (and RSC where applicable), and is documented and recorded — with notification to the regulator within 30 days.⁵
• 10 CFR 35.3045 / 35.3047 — Event reporting. Medical events and doses to an embryo/fetus or nursing child carry defined notification timelines the RSO must meet.³
• 10 CFR Part 20 — Standards for Protection Against Radiation. Dose limits (5 rem/yr occupational TEDE; 0.1 rem/yr public), the monitoring trigger at 10% of a limit (20.1502), surveys (20.1501), and the ALARA program and review requirements of 20.1101.⁴⁸
• NUREG-1556 Volume 9 — the NRC's program-specific guidance for medical-use licenses, including the model radiation protection and ALARA program content reviewers expect to see implemented.¹³

Jurisdiction follows the same rule as the rest of the materials program: the NRC directly regulates non-Agreement States and Washington DC, while Florida, Maryland, Virginia, California, and Nevada are Agreement States whose own radiation-control programs license and inspect under requirements at least as stringent as the NRC's.¹⁴ An Agreement State's RSO requirements mirror 10 CFR 35.24 and 35.50 because state programs must be compatible with the NRC's. And the byproduct-versus-machine boundary still applies: the RSO's Part 35 authority covers radioactive (byproduct) material, while diagnostic X-ray equipment (CT, radiography/fluoroscopy, mammography) is regulated by the FDA and the states — often overseen by the same physics and safety personnel, but under a separate framework. For one state's specifics, see our guide to Florida radiation safety requirements.

Frequently Asked Questions (FAQs)

What does a Radiation Safety Officer do?

The RSO is the individual named on a radioactive material license who is responsible for implementing the radiation protection program. Under 10 CFR 35.24, the RSO ensures radiation safety activities follow approved procedures and regulatory requirements, oversees day-to-day operations, keeps exposures ALARA, investigates overexposures and medical events, and has the authority to stop unsafe operations.

What are the qualifications to be an RSO under 10 CFR 35.50?

There are three principal routes: certification by an NRC-recognized specialty board; completion of 200 hours of classroom and laboratory training plus one year of full-time radiation safety experience, with a preceptor written attestation; or being an Authorized User, Authorized Medical Physicist, or Authorized Nuclear Pharmacist already identified on the license whose training covers the radionuclides and uses in the program.

Does every license need a Radiation Safety Committee?

No. A Radiation Safety Committee is required for broad-scope (Type A) medical-use licensees, where it reviews and approves authorized users, the RSO, and major program changes. Limited- and standard-scope licensees are not required to have one, though many larger institutions maintain a committee as a governance best practice.

What is the difference between an RSO and an Associate RSO?

The RSO is the single individual with overall responsibility for the radiation protection program. An Associate RSO, qualified under 10 CFR 35.51, may be named on the license to oversee specific types of use under the RSO's overall direction. Naming an ARSO does not relieve the RSO of overall program responsibility.

What is ALARA and what are investigational levels?

ALARA means keeping exposures As Low As Reasonably Achievable, a documented commitment required under 10 CFR 20.1101. Investigational levels are facility-set dose thresholds — commonly tiered as Level I and Level II as fractions of the 5 rem/yr occupational limit — that trigger graded RSO review and corrective action before a worker approaches the regulatory limit.

What must an RSO report to the NRC?

The RSO ensures timely reporting of medical events (10 CFR 35.3045), doses to an embryo/fetus or nursing child above thresholds (35.3047), lost or stolen sources, overexposures, and certain leaking sealed sources. A medical event generally requires a telephone report to the NRC or Agreement State within 24 hours and a written report within 15 days.

Can a consultant serve as an outsourced RSO?

Yes. Many smaller imaging centers and nuclear medicine clinics engage a qualified medical physicist or health physicist as their named RSO or as RSO support, provided that person meets 10 CFR 35.50 and is given the documented authority and resources required by 10 CFR 35.24. The arrangement must be reflected on the license and in the radiation protection program.

Key Takeaways

• The RSO is the named, qualified individual responsible for implementing a facility's radiation protection program; 10 CFR 35.24 grants the authority and assigns the responsibilities, including the standing authority to stop unsafe operations.¹
• Qualification under 10 CFR 35.50 follows one of three routes — board certification; 200 hours of training plus one year of experience with a preceptor attestation; or status as an existing Authorized User/Medical Physicist/Nuclear Pharmacist on the license — with the Associate RSO governed by 35.51.²⁷
• The RSO's duties map to specific CFR sections on a defined cadence: surveys and monitoring (Part 20), instrument QC and leak tests (35.60/35.61/35.67), training (19.12/35.27), program changes (35.26), and event reporting (35.3045).³⁴⁵
• ALARA investigational levels — commonly Level I and Level II set as fractions of the 5 rem/yr limit — let the RSO catch and correct dose trends well before the regulatory limit; monitoring itself is triggered at 10% of a limit (0.5 rem/yr) under 20.1502.⁴⁸
• A Radiation Safety Committee is required for broad-scope (Type A) licensees and reviews users, the RSO, and major program changes; smaller licensees rely on the RSO with an annual program review under 20.1101(c).⁸⁹
• Florida, Maryland, Virginia, California, and Nevada are Agreement States with RSO requirements mirroring the NRC's; Washington DC is regulated directly by the NRC.¹⁴

Conclusion

The Radiation Safety Officer is the operational backbone of every medical radioactive-material program. The regulations define the role precisely — 10 CFR 35.24 for authority and responsibilities, 35.50/35.51 for who may hold it, 35.26 for how the program changes, 35.3045 for event reporting, and Part 20 for the dose limits, monitoring, and ALARA framework the RSO administers.¹²³⁴⁵ What separates a compliant, genuinely safe program from one that merely looks compliant is not the size of the binder; it is an RSO who has been given real authority, protected time, and resources, and who runs surveys, monitoring, instrument QC, training, investigational levels, and the annual program review as a continuous, documented system. Facilities that empower the RSO this way spend their time on patients and safety, not on deficiency letters.

How DRPS Can Help

The RSO role demands specific qualifications, dedicated time, and continuous program management — a combination many imaging centers and nuclear medicine clinics cannot staff internally. Diagnostic Radiation Physics Services (DRPS) supports facilities across Florida, Maryland, Virginia, Washington DC, California, and Nevada with:

• Named RSO and RSO program support — board-certified physicists serving as your 10 CFR 35.50-qualified RSO or backing your in-house RSO with program management, annual reviews, and audit readiness.
• Radiation protection and ALARA program development — written procedures, investigational levels, and the documented authority that 10 CFR 35.24 requires.
• Annual program reviews and mock inspections against the NRC and Agreement State checklists.
• Survey-meter and dose-calibrator calibration and QC, dosimetry-program review, and shielding evaluations that supply the defensible data the program rests on.
• Medical-event and incident investigation support, license-amendment assistance, and corrective-action planning.

Contact DRPS to discuss your program, or learn more about our Radiation Safety Officer services, radioactive material license support, and medical physicist consulting.

Related Resources

• NRC radioactive material license guide
• Common radiation safety violations
• Occupational exposure monitoring
• Florida radiation safety requirements
• Radiation Safety Officer consulting
• Radioactive material license support

References

1. U.S. Nuclear Regulatory Commission. 10 CFR 35.24, Authority and responsibilities for the radiation protection program. ecfr.gov
2. U.S. Nuclear Regulatory Commission. 10 CFR 35.50, Training for Radiation Safety Officer. ecfr.gov
3. U.S. Nuclear Regulatory Commission. 10 CFR Part 35, Medical Use of Byproduct Material. ecfr.gov
4. U.S. Nuclear Regulatory Commission. 10 CFR Part 20, Standards for Protection Against Radiation. ecfr.gov
5. U.S. Nuclear Regulatory Commission. 10 CFR 35.26, Radiation protection program changes. ecfr.gov
6. U.S. Nuclear Regulatory Commission. Enforcement Policy. nrc.gov
7. U.S. Nuclear Regulatory Commission. 10 CFR 35.51, Training for an Associate Radiation Safety Officer. ecfr.gov
8. U.S. Nuclear Regulatory Commission. 10 CFR 20.1101, Radiation protection programs. ecfr.gov
9. U.S. Nuclear Regulatory Commission. 10 CFR 35.24(c)–(f) and Subpart C, Radiation Safety Committee for broad-scope licensees; see also 10 CFR Part 33, Specific Licenses of Broad Scope. ecfr.gov
10. U.S. Nuclear Regulatory Commission. Regulatory Guide 8.13 (and NUREG-1556 Vol 9 model ALARA program), ALARA program and investigational levels. nrc.gov
11. Sjögreen-Gleisner K, Flux G, Bacher K, et al. EFOMP policy statement No. 19: Dosimetry in nuclear medicine therapy — Molecular radiotherapy. Phys Med. 2023;116:103166. doi:10.1016/j.ejmp.2023.103166. doi.org
12. Ioannidou SP, Katsouli M, Doika E. Commissioning of the first hospital-based PET radiopharmaceutical cyclotron in Greece: personnel dose assessment. J Radiol Prot. 2024;44(2):021510. doi:10.1088/1361-6498/ad460c. doi.org
13. U.S. Nuclear Regulatory Commission. NUREG-1556, Volume 9, Revision 3: Consolidated Guidance About Materials Licenses — Program-Specific Guidance About Medical Use Licenses. nrc.gov
14. U.S. Nuclear Regulatory Commission. Agreement State Program. nrc.gov