Guide

10 CFR 35 medical use readiness for radiopharmaceutical sites

10 CFR Part 35 is the US Nuclear Regulatory Commission's medical-use regulation — it controls who may possess and use byproduct material in humans, what training the Authorized User and Radiation Safety Officer must have, and how written directives govern therapeutic administrations. Part 35 is enforced directly by NRC in non-Agreement States and by state-level radiation-control programs in the 39 Agreement States (whose rules must be compatible but are often more detailed). Every commercial radiopharmaceutical manufacturer, hospital therapy program, and PET imaging center in the US operates under Part 35 in parallel with 21 CFR 212 or USP <825>.

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License types and subparts

Subpart C covers the general administrative framework. Subpart D handles unsealed byproduct material for uptake, dilution, and excretion studies (e.g., I-123 thyroid uptake). Subpart E covers imaging and localization (F-18 FDG, Tc-99m kits, Ga-68 generators). Subpart F is the high-risk subpart — unsealed therapeutic use including I-131 sodium iodide therapy and Lu-177 / Y-90 antibody and peptide therapies. Subpart H covers sealed sources for brachytherapy.

Authorized User and RSO — the two named people

Every license must name a Radiation Safety Officer (35.50, training and experience requirements explicit) and at least one Authorized User per modality. The AU's training and experience must match the subpart — Subpart F therapy AUs need substantially more documented hours than Subpart E imaging AUs. NRC's Form 313A series captures this. AU and RSO appointments require license amendment, not just internal HR action.

Written directive — the core therapy control

Under 35.40 every Subpart F therapy administration requires a written directive signed by the AU before administration, specifying patient, radionuclide, activity, dosage form, and route. Any deviation greater than 20 percent of prescribed activity, or to the wrong patient/radionuclide/route, is a medical event under 35.3045 and must be reported to NRC within 24 hours by telephone and 15 days in writing.

Patient release and instructions (35.75)

Patients dosed with therapeutic activities of I-131, Lu-177, or other long-lived isotopes can only be released when the projected total effective dose equivalent to any other individual is below 5 mSv (500 mrem). Documented written instructions on radiation-safety precautions are mandatory and a frequent inspection finding when missing or generic.

Agreement States — the operational wrinkle

39 Agreement States enforce their own compatible rules; California, Texas, New York, Illinois, and Florida concentrate most US radiopharma activity. Multi-state networks must maintain state-specific licenses in parallel — there is no single national license. Agreement-state rule packages often diverge on patient-release instructions, instrument calibration cadence, and RSO continuing-education requirements.

Inspection cadence and common findings

NRC and Agreement-State inspections run on a 1–5 year cadence depending on subpart and prior performance. The 2020–2025 finding pattern: missing or inadequate written directives, incomplete medical-event investigations, lapsed dose calibrator constancy/linearity records, untimely survey or wipe-test records, and survey instrument calibration overdue. Medical events are the single highest-severity category and trigger formal Enforcement actions.

Standards covered in this guide

Each standard, retailer code or assurance scheme referenced above has its own deep-dive page with scope, audit detail and common pitfalls.

ALCOA+

The nine-letter mnemonic regulators use to grade your data integrity — and what every Part 11 audit really tests.

CAPA

Structured investigation + fix loop for recurring problems — required by every quality regime.

Where this lives in V5 Ultimate

The clauses above aren't theoretical — every one maps to a shipped module and an industry profile. Jump to the parts of the product that turn this guide into evidence on a Monday morning.

Industries this hits hardest

Frequently asked

Do we need separate licenses for imaging and therapy?

Not separate licenses, but separate subpart authorizations on the same license, each with its own AU(s). A Subpart E imaging program cannot administer Lu-177 therapy without amending the license to add Subpart F authorization.

What is the difference between a medical event and a recordable event?

A medical event under 35.3045 is administration deviating by >20% from prescribed activity, wrong patient, wrong radionuclide, wrong route, or wrong site — reportable to NRC. A recordable event is a smaller deviation captured in internal records but not reported.

Does 10 CFR 35 apply to a commercial radiopharmaceutical manufacturer?

Manufacturers possess byproduct material under a different NRC license type (commercial possession), not Part 35 — Part 35 applies to medical end users. But manufacturers shipping to medical users must understand 35 so labeling, calibration, and dose-calibration instructions are usable downstream.

How does Part 35 interact with the FDA's authority?

Part 35 governs the use of the radionuclide; FDA governs the drug product itself (efficacy, GMP, labeling). They overlap at the bedside: an AU administering an approved drug under a written directive is operating under both regimes.

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