Residency · Residency · Nuclear Medicine
NRC Regulatory Framework for Nuclear Medicine
Introduction
The Nuclear Regulatory Commission (NRC) regulates the medical use of byproduct material in the United States under 10 CFR Part 35 (Medical Use of Byproduct Material). Understanding the NRC's regulatory framework is essential for nuclear medicine physicians, who may serve as authorized users (AUs) or radiation safety officers (RSOs). Agreement states may have additional or equivalent regulations administered by state radiation control programs.
Regulatory Structure
NRC Authority
The NRC was established by the Energy Reorganization Act of 1974 as the successor to the Atomic Energy Commission. It regulates reactor-produced radioactive materials, known as byproduct material. The NRC does not regulate naturally occurring radioactive material (NORM), accelerator-produced material in agreement states, or x-ray equipment. Regulation of naturally occurring and accelerator-produced radioactive material (NARM) was transferred to the NRC under the Energy Policy Act of 2005.
Agreement States
Agreement states are those that have entered into agreements with the NRC to regulate byproduct material within their borders. These states must maintain regulatory programs that are adequate and compatible with NRC regulations. Currently, 39 agreement states regulate their own radioactive materials programs. Non-agreement states are directly regulated by the NRC.
Key Regulatory Documents
The primary regulatory documents include 10 CFR Part 20 (Standards for Protection Against Radiation), 10 CFR Part 35 (Medical Use of Byproduct Material), 10 CFR Part 30 (Rules of General Applicability to Domestic Licensing), and NUREG-1556, Volume 9 (Consolidated Guidance for Medical Use Licenses).
10 CFR Part 35: Medical Use of Byproduct Material
License Types
A specific license is required for possession and use of byproduct material. A broad scope license provides greater flexibility, allowing the institution to manage its own radiation safety program. A limited specific license is more restrictive, authorizing only specific isotopes and quantities.
Authorized Users and Training Requirements
An authorized user (AU) is a physician authorized on the radioactive materials license for medical use. Training pathways vary by category of use. Section 35.100 covers uptake, dilution, and excretion studies. Section 35.200 covers imaging and localization studies. Section 35.300 covers written directive-required uses, which are therapeutic doses. Section 35.390 addresses therapeutic use of unsealed byproduct material. Section 35.396 covers parenteral administration for non-sodium iodide therapies. Sections 35.400 and 35.500 address manual and remote afterloader brachytherapy, and section 35.600 covers sealed source therapy such as gamma knife. The most common pathway to becoming an authorized user is board certification through the ABR or ABNM, though an alternate pathway with preceptor attestation is also available.
Radiation Safety Officer (RSO)
The RSO must be identified on the license and is responsible for implementing the radiation safety program. Training requirements are specified in 10 CFR 35.50. The RSO's duties include maintaining ALARA, overseeing surveys, and managing radioactive materials. The RSO has the authority to stop unsafe practices.
Written Directives
When Required
A written directive under 10 CFR 35.40 is required for I-131 sodium iodide greater than 1.11 MBq (30 microcuries), any therapeutic dose of unsealed byproduct material, all brachytherapy administrations, and all gamma stereotactic radiosurgery treatments.
Content Requirements
The written directive must include verification of patient identity by two methods, the radiopharmaceutical name, dosage, and route of administration. It must be signed and dated before administration. Amendments are allowed before completion if properly documented.
Procedures for Administration
Patient identification is verified using the patient's name and one additional identifier. The written directive must be completed and signed prior to administration. Post-administration documentation includes the actual administered activity. Records are retained for 3 years.
Radiation Safety Program Requirements
ALARA Program
An institutional ALARA program reflects the commitment to keeping doses as low as reasonably achievable. Annual review of occupational exposures is required. Investigation levels are defined as Level I (exceeding 10% of the applicable limit) and Level II (exceeding 30% of the applicable limit). Management and the RSO review exposure trends.
Personnel Monitoring
Personnel monitoring is required when a worker is likely to receive more than 10% of the annual occupational dose limits. Annual dose limits are 50 mSv total effective dose equivalent and 500 mSv to the extremities. The declared pregnant worker limit is 5 mSv for the gestation period. Dosimetry records are retained until license termination.
| Category | Annual Dose Limit | Notes |
|---|---|---|
| Occupational (TEDE) | 50 mSv (5 rem) | Whole body |
| Occupational (extremity) | 500 mSv (50 rem) | Hands/feet (ring badge) |
| Occupational (lens of eye) | 150 mSv (15 rem) | — |
| Declared pregnant worker | 5 mSv (0.5 rem) for gestation | Monthly monitoring required |
| Individual member of public | 1 mSv (100 mrem)/year | In unrestricted areas |
| ALARA Investigation Level I | >10% of limit | Review required |
| ALARA Investigation Level II | >30% of limit | Action required |
Surveys and Contamination Control
Daily surveys are performed in radiopharmaceutical preparation areas. Weekly wipe tests assess removable contamination. The trigger level for unrestricted areas is 200 dpm per 100 cm2. Survey meters are calibrated annually.
Radioactive Material Security
Radioactive material must be secured from unauthorized access at all times. Inventory and accountability records are maintained. Transportation must comply with DOT regulations. Package receipt procedures include wipe testing within 3 hours of receipt.
Dose Limits for the Public
The total effective dose equivalent to individual members of the public is limited to 1 mSv (100 mrem) per year. The dose rate in unrestricted areas must not exceed 0.02 mSv (2 mrem) in any one hour. Patient release criteria are based on administered activity or measured dose rate.
Clinical Pearls
A written directive must be completed and signed before administration of any therapeutic dose of unsealed byproduct material or any I-131 sodium iodide dose exceeding 1.11 MBq (30 microcuries).
The authorized user bears ultimate responsibility for the medical use of byproduct material, including proper patient identification, dose verification, and compliance with the written directive.
Agreement states administer their own radiation control programs but must maintain standards that are adequate and compatible with NRC regulations.
The annual occupational dose limit is 50 mSv total effective dose equivalent, with a pregnancy dose limit of 5 mSv for the entire gestation period.
References
- U.S. Nuclear Regulatory Commission. "10 CFR Part 35 -- Medical Use of Byproduct Material." NRC Regulations.
- U.S. Nuclear Regulatory Commission. "NUREG-1556, Vol. 9, Rev. 3: Consolidated Guidance About Materials Licenses -- Medical Use." 2019.
- U.S. Nuclear Regulatory Commission. "10 CFR Part 20 -- Standards for Protection Against Radiation." NRC Regulations.
- Siegel JA, et al. "NRC Regulation of Nuclear Medicine: Guide for Diagnostic Nuclear Medicine and Radiopharmaceutical Therapy." J Nucl Med. 2020;61(Suppl 2):13S-17S.