# 91 FR 47042: Reducing Barriers to Medical Use Licensing

> Federal · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-15080

## Section

- **Citation:** 91 FR 47042
- **Heading:** Reducing Barriers to Medical Use Licensing
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Federal Register / Vol. 91 / 91 FR 47042

## Text

NUCLEAR REGULATORY COMMISSION 10 CFR Part 35 [NRC-2025-1237] RIN 3150-AL50 Reducing Barriers to Medical Use Licensing AGENCY:
Nuclear Regulatory Commission.

ACTION:
Proposed rule and guidance; request for comment.

SUMMARY:
The U.S. Nuclear Regulatory Commission (NRC) is proposing to amend its regulations to reduce barriers to medical use licensing. This proposed rule responds to Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” which requires the NRC to conduct a review and wholesale revision of its regulations. This proposed rule, if adopted, would reduce overly prescriptive regulations, increase flexibility, and modernize radiation safety practices for the medical use of byproduct material. It also would enable more efficient and predictable licensing for emerging medical technologies and reduce unnecessary burden in training and experience requirements for medical authorized users. The NRC is revising guidance for this proposed rule. This proposed rule also would incorporate minor editorial corrections.

DATES:
Comments must be submitted electronically using https://www.regulations.gov by 11:59 p.m. eastern time on September 10, 2026.

ADDRESSES:
Submit your comments, identified by Docket ID NRC-2025-1237, at https://www.regulations.gov. If your material cannot be submitted using https://www.regulations.gov, call or email the individuals listed in the FOR FURTHER INFORMATION CONTACT section of this document for alternate instructions.
Do not include any personally identifiable information (such as name, address, or other contact information) or confidential business information that you do not want publicly disclosed. All comments are public records; they are publicly displayed exactly as received, and will not be deleted, modified, or redacted. Comments may be submitted anonymously.
Follow the search instructions on https://www.regulations.gov to view public comments.
You can read a plain language description of this proposed rule at https://www.regulations.gov/docket/ NRC-2025-1237. For additional direction on obtaining information and submitting comments, see “Obtaining Information and Submitting Comments” in the SUPPLEMENTARY INFORMATION section of this document.
FOR FURTHER INFORMATION CONTACT:
Irene Wu, Office of Nuclear Material Safety and Safeguards, telephone: 301-415-1951, email: Irene.Wu@nrc.gov and Katie Tapp, Office of Nuclear Material Safety and Safeguards, telephone: 301-415-0236, email: Katherine.Tapp@nrc.gov. Both are staff of the U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

SUPPLEMENTARY INFORMATION:
EXECUTIVE SUMMARY
A. Need for Regulatory Action
On May 23, 2025, President Donald J. Trump signed Executive Order (E.O.) 14300, “Ordering the Reform of the Nuclear Regulatory Commission.” E.O. 14300 directs the NRC to conduct a comprehensive review and wholesale revision of its regulations and guidance documents in alignment with objectives outlined in section 2 of the E.O. This rulemaking addresses section 5 of the E.O., focusing on the regulations in title 10 of the Code of Federal Regulations (10 CFR) part 35, “Medical Use of Byproduct Material,” and guidance documents related to the medical use of byproduct material. The proposed changes would facilitate the licensing of innovative technologies while maintaining the NRC's commitment to public health and safety. The proposed changes also aim to improve efficiency, reduce regulatory burden, and ease administrative burden for the NRC, Agreement States, licensees, and individuals or entities that seek medical use licenses.
B. Major Provisions
The major provisions of this proposed rule include the following:
1. Broadening the definition of “physician” to include foreign-trained individuals as long as they are licensed by a State or Territory of the United States, the District of Columbia, or the Commonwealth of Puerto Rico to prescribe drugs in the practice medicine.
2. Replacing the recentness in training requirement (within 7 years) with a performance-based continuing education model and removing specific work experience requirements for generator systems due to changes in industry practice.
3. Eliminating the requirement for license amendments to add authorized users for diagnostic uses, allowing licensees to approve and document these users internally due to the lower risk of these non-therapeutic uses.
4. Removing prescriptive training hours requirements for physicians who have received significant radiation safety and clinical training during the completion of a clinical radiation specialty residency, while retaining the alternative board certification and cross-qualification pathways.
5. Updating work experience categories for “oral” and “parenteral” administration of any radioactive drug requiring a written directive, allowing flexibility for future radiopharmaceuticals.
6. Moving specialty board certification approval requirements to a new section for clarity and regulatory efficiency, removing specific accrediting body references in residency training requirements, and clarifying that required work experience may be supervised by an authorized user at an NRC or Agreement State licensed medical facility.
7. Codifying provisions for emerging medical technologies (EMTs) currently licensed under subpart K of 10 CFR part 35, by establishing clear licensing pathways, training and experience requirements, and performance-based safety criteria. The EMTs include modern gamma stereotactic radiosurgery (GSR) devices, ophthalmic source/applicator devices, generators, and microsources.
8. Establishing clear requirements for rubidium-82 (Rb-82) generators, including codified definitions for breakthrough, calibration flexibility for dynamic systems, and updated licensing and training provisions to codify enforcement guidance.
9. Removing the written directive requirement for diagnostic administrations of sodium iodide I-131, aligning regulatory oversight with current clinical practice and other diagnostic administrations with comparable risk.
10. Refining written directive and medical event reporting requirements to exclude events caused by emergent patient conditions or real-time clinical decisions, while preserving reporting for events with potential safety significance, such as those involving equipment defects or unintended harm, reducing unnecessary burden and improving regulatory clarity.
11. Refining embryo/fetus dose reporting requirements to exclude cases where pregnancy could not reasonably be determined prior to administration, aligning oversight with clinical realities and reducing unnecessary reporting.
12. Expanding decay-in-storage eligibility by increasing the allowable
13. Eliminating the license amendment requirement for human subject research already approved by an Institutional Review Board (IRB) and covered under existing medical use authorizations, streamlining research initiation while maintaining safety and ethical oversight.
14. Removing duplicative and prescriptive requirements for mobile medical services, aligning them with general radiation safety regulations and providing licensees greater flexibility without compromising protection of patients, workers, or the public.
15. Extending the temporary Radiation Safety Officer (RSO) duration and refining Radiation Safety Committee (RSC) requirements to reflect current clinical practice, reduce administrative burden, and focus oversight on higher-risk therapeutic uses requiring written directives.
16. Removing outdated and redundant provisions across 10 CFR part 35, including prescriptive mobile medical survey requirements, obsolete waiver clauses, and recordkeeping requirements, to modernize the regulatory framework.
C. Costs and Benefits
This proposed rule is considered a deregulatory action and is expected to reduce barriers to medical use licensing by enabling more efficient and predictable licensing, increasing flexibility, and easing administrative burden for the NRC, Agreement States, licensees and individuals or entities that seek medical use licenses. Over the 5-year analysis period (2027-2031), the proposed revisions are estimated to generate net savings of $39.1 million (savings minus costs), undiscounted. Using 2024 as the base year, the net present value (NPV) of these net savings is $35.6 million, discounted at 3 percent, or $31.7 million, discounted at 7 percent. The licensees, accounting for the largest share of net savings, would save about $30.5 million over 5 years, undiscounted, with an NPV of $27.8 million discounted at 3 percent, or $24.8 million discounted at 7 percent. Overall, the projected annualized cost savings would be $7.2 million discounted at 3 percent, or $6.4 million discounted at 7 percent. Although this proposed rule would reduce barriers to medical-use licensing (including new technologies) and generate net savings, some costs would still be incurred over the 5-year period, primarily due to small increases in recordkeeping requirements from the proposed new regulations for new technologies and aligning with other modalities contained in 10 CFR part 35, as well as implementation costs. The additional recordkeeping costs, which represent operational costs for licensees, are estimated at $2.4 million (undiscounted), $2.2 million (discounted at 3 percent), and $2.0 million (discounted at 7 percent) over this 5-year period. Implementation costs for both NRC and industry stakeholders are estimated at about $2.9 million (undiscounted), $2.8 million (discounted at 3 percent), and $2.7 million (discounted at 7 percent). When compared with the projected savings, the operational (expanded recordkeeping requirements) costs account for a small share, about 6 percent of the projected net savings.
For more information, please see the regulatory analysis included later in this notice.
Table of Contents
I. Obtaining Information and Submitting Comments A. Obtaining Information B. Submitting Comments II. Executive Order 14300: Ordering the Reform of the Nuclear Regulatory Commission III. Background A. Training and Experience B. Emerging Medical Technologies C. Rubidium-82 Generators D. Written Directives for Diagnostic Sodium Iodide I-131 E. Reductions in Event Reporting F. Decay-in-Storage IV. Discussion A. Training and Experience B. Emerging Medical Technologies C. Rubidium-82 Generators D. Other Topics V. Specific Requests for Comments VI. Regulatory Flexibility Certification VII. Regulatory Analysis A. Need for the Rule B. Analytical Framework C. Estimated Costs and Savings of This Proposed Rule D. Rulemaking and Implementation Costs VIII. Backfitting and Issue Finality IX. Cumulative Effects of Regulation X. Plain Writing XI. National Environmental Policy Act A. Introduction B. Environmental Impacts of the Proposed Agency Action C. Summary of the Environmental Impacts of the Proposed Agency Action D. Environmental Impacts of the Alternative to the Proposed Agency Action E. Agencies and Persons Consulted F. Draft Finding of No Significant Impact XII. Paperwork Reduction Act XIII. Executive Orders A. Executive Order 12866: Regulatory Planning and Review (as Amended by Executive Order 14215, Ensuring Accountability for All Agencies) B. Executive Order 14154: Unleashing American Energy C. Executive Order 14192: Unleashing Prosperity Through Deregulation D. Executive Order 14267: Reducing Anti-Competitive Regulatory Barriers E. Executive Order 14270: Zero-Based Regulatory Budgeting To Unleash American Energy F. Executive Order 14294: Fighting Overcriminalization in Federal Regulations XIV. Coordination With NRC Agreement States XV. Compatibility of Agreement State Regulations XVI. Coordination With the Advisory Committee on the Medical Uses of Isotopes XVII. Voluntary Consensus Standards XVIII. Availability of Guidance XIX. Availability of Documents I. Obtaining Information and Submitting Comments
A. Obtaining Information
Please refer to Docket ID NRC-2025-1237 when contacting the NRC about the availability of information for this action. You may obtain publicly available information related to this action by any of the following methods:
• Federal Rulemaking website: Go to https://www.regulations.gov and search for Docket ID NRC-2025-1237.
• NRC's Agencywide Documents Access and Management System (ADAMS): You may obtain publicly available documents online in the ADAMS Public Documents collection at https://www.nrc.gov/reading-rm/adams.html. To begin the search, select “Begin ADAMS Public Search.” For problems with ADAMS, please contact the NRC's Public Document Room (PDR) reference staff at 1-800-397-4209, at 301-415-4737, or by email to PDR.Resource@nrc.gov. For the convenience of the reader, instructions about obtaining materials referenced in this document are provided in the “Availability of Documents” section.
• Public Meeting: The NRC plans to conduct a public meeting to describe the proposed amendments and answer questions from the public on the proposed rule. The NRC will publish a notice of the location, time, and agenda of the meeting on the NRC's public meeting website within 10 calendar days of the meeting. Stakeholders should monitor the NRC's public meeting website for information about the public meeting at: https://www.nrc.gov/public-involve/public-meetings/index.cfm.
• NRC's PDR: The PDR, where you may examine and order copies of publicly available documents, is open PDR.Resource@nrc.gov or call 1-800-397-4209 or 301-415-4737, between 8 a.m. and 4 p.m. eastern time, Monday through Friday, except Federal holidays.
B. Submitting Comments
Comments must be submitted electronically using https://www.regulations.gov no later than 11:59 p.m. eastern time on September 10, 2026. Please include Docket ID NRC-2025-1237 in your comment submission.
The NRC cautions you not to include identifying or contact information that you do not want to be publicly disclosed in your comment submission. The NRC will post all comment submissions at https://www.regulations.gov as well as enter the comment submissions into ADAMS. The NRC does not routinely edit comment submissions to remove identifying or contact information.
If you are requesting or aggregating comments from other persons for submission to the NRC, then you should inform those persons not to include identifying or contact information that they do not want to be publicly disclosed in their comment submission. Your request should state that the NRC does not routinely edit comment submissions to remove such information before making the comment submissions available to the public or entering the comment into ADAMS.
II. Executive Order 14300: Ordering the Reform of the Nuclear Regulatory Commission
On May 23, 2025, President Donald J. Trump signed Executive Order (E.O.) 14300. Section 5, “Reforming and Modernizing the NRC's Regulations,” requires the NRC to undertake a review and wholesale revision of its regulations and guidance documents as guided by the policies set forth in section 2 of the E.O. This rulemaking addresses section 5 with a focus on the regulations and guidance documents pertaining to the medical use of byproduct material.
III. Background
Since 1946, physicians have used byproduct material in the diagnosis, treatment, and research of medical conditions. Over the decades, the medical use of byproduct material has evolved significantly, driven by advances in isotopes, procedural complexity, and medical technologies. Today, more than 20 million patients undergo procedures involving byproduct material each year in the United States, a number expected to grow as new medical devices and radiopharmaceuticals are developed, researched, and approved by the U.S. Food and Drug Administration (FDA).
As part of its ongoing efforts to modernize the regulatory framework in accordance with E.O. 14300, the NRC has reviewed its regulations governing the medical use of byproduct material under 10 CFR part 35. This review has led the NRC to propose changes to the training and experience requirements to ensure they are risk-informed, reduce unnecessary burden on physicians who already receive substantial radiation safety training as part of their medical education, and enhance regulatory clarity. In addition, the NRC proposes to codify certain well-established EMTs and regulatory provisions specific to the use of Rb-82 generators. The NRC uses “well-established EMTs” to refer to EMTs with extensive operating experience and widespread clinical use, for which licensing and training practices are stable and supported by NRC and Agreement State experience. In selecting EMTs for codification, the NRC prioritized those with the most extensive history and highest levels of use and with performance-based safety criteria that can be standardized in 10 CFR part 35. These updates aim to improve efficiency and predictability in licensing and oversight. The proposed changes also seek to eliminate outdated or unnecessarily burdensome requirements, allow for flexibility to facilitate licensing of innovative devices and medical uses, align regulations with current clinical practices, and improve clarity for licensees. Nothing in this proposed rule would relieve licensees from complying with applicable FDA, Federal, or State requirements or National Institutes of Health grant compliance obligations related to the use of radioactive drugs or devices. These proposed changes are detailed in Section IV, “Discussion,” of this document.
Several key topics addressed in this proposed rule benefit from additional context and relevant background information, as provided in the following sections.
A. Training and Experience
The training and experience requirements in 10 CFR part 35 are designed to ensure that individuals authorized to use byproduct material in medical applications possess the necessary knowledge, skills, and competencies to ensure radiation safety. The regulations in 10 CFR part 35 include provisions related to the training and experience of physicians who use or supervise the medical use of byproduct material, known as authorized users (AUs). The AU training and experience requirements in 10 CFR part 35 have evolved over time in response to changes in medical practice, stakeholder input, and broader shifts in medical education. The current framework includes requirements for classroom and laboratory training and supervised work experience that requires a prescriptive number of hours for all AUs, regardless of whether they completed residency training in a clinical radiation specialty. This is in addition to the individual (1) being a physician licensed to prescribe drugs in the practice of medicine by their respective State or Territory of the United States, the District of Columbia, or the Commonwealth of Puerto Rico; (2) either having obtained written attestation that they are able to independently fulfill the radiation safety-related duties as an AU for the medical uses authorized, or having received board certification from a board recognized by the NRC or an Agreement State; and (3), in some cases, having obtained device-specific training. 10 CFR part 35 also contains training and experience requirements for other individuals important to radiation safety, including authorized medical physicists (AMPs), authorized nuclear pharmacists (ANPs), and RSOs.
The NRC last made significant revisions to the training and experience requirements in 2002 and 2005. Since then, stakeholders have raised concerns about the impact of these requirements, particularly the prescriptive number of hours required for unsealed use of byproduct material for therapy contained in § 35.390, “Training for use of unsealed byproduct material for which a written directive is required.” From 2015 to 2016, both the NRC staff and the Advisory Committee on the Medical Uses of Isotopes (ACMUI) independently reviewed the training and experience requirements for medical uses authorized under § 35.300, “Use of unsealed byproduct material for which a written directive is required.” In its March 2016 report, the ACMUI concluded that no changes to the 700-hour requirement were warranted at that time as they found no evidence that the requirement adversely affected patient access. However, the ACMUI recommended forming a subcommittee to periodically review the training and experience requirements and make recommendations as needed.
In 2016, the ACMUI established a subcommittee to review the training and experience requirements across all modalities regulated under 10 CFR part
The subcommittee's draft interim report, discussed in a public meeting on March 1, 2018, expressed concern about the declining number of nuclear medicine physicians and the potential long-term implications for patient access. While the subcommittee acknowledged the difficulty in quantifying the impact of this trend, it noted the absence of data suggesting a surplus of AUs and emphasized the need to consider future workforce needs.
In response to these ongoing concerns, the Commission issued Staff Requirements Memorandum (SRM)-M170817 on August 17, 2017, directing the NRC staff to evaluate whether tailored training and experience requirements should be established for different categories of radiopharmaceuticals, how those categories should be defined ( e.g., by risk or delivery method), and whether training and experience requirements should be based on hours or competency. The staff's initial evaluation was documented in SECY-18-0084, “Staff Evaluation of Training and Experience Requirements for Administering Different Categories of Radiopharmaceuticals.” In that paper, the staff concluded that additional stakeholder outreach was needed.
Following further engagement with stakeholders, including the ACMUI and Agreement States, the NRC staff submitted SECY-20-0005, “Rulemaking Plan for Training and Experience Requirements for Unsealed Byproduct Material (10 CFR part 35),” to the Commission on January 13, 2020. On January 27, 2022, the Commission issued SRM-SECY-20-0005, maintaining the existing training and experience requirements and directing staff to continue to obtain stakeholder input on training and experience requirements for EMTs as part of the broader rulemaking effort to update 10 CFR part 35.
At the time E.O. 14300 was issued on May 23, 2025, the NRC staff was actively evaluating training and experience requirements for Rb-82 generators and EMTs. The E.O. directed the NRC to undertake a comprehensive review and modernization of its regulations, including those governing the medical use of byproduct material. The proposed changes to training and experience in this rulemaking are in response to the E.O. and build upon the historical evolution of the training and experience requirements and the extensive body of stakeholder feedback and Commission direction developed over the past two decades.
Specifically, this proposed rulemaking removes prescriptive hours for physicians who have received significant radiation safety and clinical training over years of a clinical radiation specialty residency. In addition, it proposes to remove the requirement for diagnostic AUs to be listed on a license and removes outdated training topics and requirements associated with arbitrary dates of when physicians last received training, allowing licensees to focus training and experience on topics more relevant to clinical practice. Finally, the NRC proposes changes to the training and experience requirements' organization for all authorized individuals ( i.e., AUs, AMPs, ANPs, and RSOs) to enhance regulatory clarity.
B. Emerging Medical Technologies
In 2002, the NRC added subpart K, “Other Medical Uses of Byproduct Material or Radiation from Byproduct Material,” (§ 35.1000) to 10 CFR part 35 to provide a flexible regulatory framework for licensing new or existing EMTs that do not fit within the existing subparts of 10 CFR part 35. The regulations in § 35.1000 define the process to obtain a license or license amendment for EMTs. EMTs often require unique provisions for training and experience, facility and equipment specifications, or other safety-related considerations that are not addressed in the existing 10 CFR part 35 subparts (subparts D through H). As a result, the NRC and Agreement States evaluate each EMT on a case-by-case basis to determine the specific risks associated with the EMT and any additional regulatory requirements needed for its medical use and may develop model- and vendor-specific licensing guidance to support consistent and safe licensing and use.
Licensing guidance for EMTs is developed with input from the ACMUI, vendors, and regulatory staff, and includes general licensing considerations, radiation safety protocols, and training and experience expectations for individuals authorized to use the technology. While not binding, licensing guidance for EMTs provides applicants with an acceptable means to satisfy the requirements for a license for the EMT. Applicants who commit to following the EMT licensing guidance may have those commitments incorporated as license conditions. Alternatively, applicants may propose other sets of regulations and specific conditions to use the EMT that become binding through license conditions in accordance with § 35.1000.
Since 2002, the NRC and Agreement States have licensed at least 18 EMTs under subpart K, including microspheres, GSR units, photon-emitting teletherapy systems, radiopharmaceutical generator systems, and ophthalmic applicator sources and devices. While subpart K offers a quick path for licensing EMTs with unique radiation safety needs as they are being introduced, continued licensing of well-established EMTs under subpart K offers limited regulatory benefit and can lead to inconsistencies and lack of clarity, as subpart K relies on guidance and the incorporation of license conditions rather than codified rules. This approach also places a resource burden on regulators due to frequent updates of EMT-specific guidance.
On June 27, 2023, the NRC published an associated regulatory basis document, “Rubidium-82 Generators, Emerging Technologies, and Other Medical Use of Byproduct Material Regulatory Basis Document,” for public comment. The majority of the comments were in favor of incorporating well-established EMTs into the main body of 10 CFR part 35. However, to meet the timeline established in E.O. 14300 for publishing this proposed rule, the scope of EMTs addressed in this proposal has been narrowed to focus on some well-established technologies with the most extensive history and highest levels of use, such as modern GSR devices, ophthalmic source/applicator devices, generators, and microsources. Uses and EMTs not included in this rulemaking include intravascular brachytherapy systems, liquid and diffusing brachytherapy sources and devices, and radioactive seed localization. While these technologies currently remain licensed under § 35.1000, and they may be incorporated into the main body of 10 CFR part 35 in a future rulemaking depending on NRC and industry need and available resources.
C. Rubidium-82 Generators
Rb-82 generators produce Rb-82 chloride, a positron-emitting radiopharmaceutical used for cardiac imaging. These generators differ from other generators licensed under § 35.200, “Use of unsealed byproduct material for imaging and localization studies for which a written directive is not required,” due to the short 75
D. Written Directives for Diagnostic Sodium Iodide I-131
A written directive is the AU's written order for administration of byproduct material or radiation from byproduct material to a specific patient or human research subject. Section 35.40, “Written directives,” establishes requirements for which medical uses of byproduct material require written directives. Under the current regulations, a written directive is required for diagnostic administrations of sodium iodide I-131 in quantities greater than 1.11 megabecquerels (30 microcuries), even when the administration is solely for diagnostic purposes. This is the only diagnostic use that currently requires a written directive; all other uses requiring a written directive are therapeutic in nature and are subject to more stringent requirements commensurate with their higher risk. Because diagnostic sodium iodide I-131 currently requires a written directive, it is licensed under subpart E of 10 CFR part 35, which otherwise applies exclusively to therapeutic uses. In contrast, all other diagnostic uses of unsealed byproduct material are regulated under subpart D of 10 CFR part 35, which does not require a written directive and reflects the lower risk associated with diagnostic procedures.
The requirement for a written directive for diagnostic sodium iodide I-131 was established by rule on April 24, 2002. At that time, the radiation safety considerations associated with the diagnostic use of millicurie quantities of sodium iodide I-131 were considered to be more similar to therapeutic uses than to other diagnostic procedures, such as those involving technetium-99m (Tc-99m). However, the practice of nuclear medicine has evolved significantly since 2002. On October 1, 2007, the NRC published a final rule to amend 10 CFR part 35 to implement provisions of the Energy Policy Act of 2005 requiring the NRC to license medical use of accelerator-produced radioactive material, including positron emission tomography (PET) (72 FR 55864). This introduced diagnostic procedures involving higher radiation exposure risk and more complex safety considerations. As a result, the relative risk profile of diagnostic sodium iodide I-131 use has shifted.
Today, diagnostic sodium iodide I-131 is typically administered in unit dosages, often in capsule form, rather than as liquid preparations compounded onsite. This change has reduced the radiation safety risks associated with handling and administering radioactive material. Additionally, the training and expertise of diagnostic nuclear medicine staff have increased in parallel with the broader use of PET and other advanced imaging modalities. These developments have brought radiation safety considerations for diagnostic sodium iodide I-131 in line with those of other diagnostic procedures regulated under subpart D of 10 CFR part 35. There are also now over 50 years of operating experience using diagnostic dosages of sodium iodide I-131, contributing to a better understanding of diagnostic sodium iodide I-131 and safety considerations surrounding its use. For the foregoing reasons, this proposed rule would remove the requirement that diagnostic sodium iodide I-131 administrations need a written directive, moving its authorization from subpart E to subpart D of 10 CFR part 35.
E. Reductions in Event Reporting
Sections 35.3045, “Report and notification of a medical event,” and 35.3047, “Report and notification of a dose to an embryo/fetus or a nursing child,” establish the criteria for reporting medical events and dose to embryo/fetus from the administration of byproduct material or radiation from byproduct material. These events represent unintended deviations from the AU's planned administration of radioactive materials that may result in doses exceeding specified thresholds. Medical event reporting is consistent with item number 3 in the NRC's risk-informed, performance-based Medical Use Policy Statement, which states the NRC will, when justified by the risk to patients, regulate the radiation safety of patients primarily to assure the use of radionuclides is in accordance with the physician's directions. These reports enable the NRC to investigate safety concerns, ensure corrective actions are taken at a licensee level, and take action such as providing communication to the industry or working with the manufacturer and the FDA to prevent recurrence at the national level.
The NRC first required reporting of medical use errors, then termed “misadministrations,” in 1980. In 2002, the NRC comprehensively revised 10 CFR part 35, renaming “misadministrations” as “medical events” and refining the reporting criteria to focus on outcomes with potential radiation safety significance. The revised rule introduced a dose-based threshold to exclude events associated with most diagnostic procedures from reporting, recognizing their low risk. Despite these improvements, stakeholders have raised concerns that the current criteria may still result in the reporting of events that do not reflect licensee error, such as those caused by emergent patient conditions ( e.g., vascular spasms or seizures) or real-time clinical decisions made in the interest of patient care. The NRC is proposing changes to medical event reporting requirements to avoid unnecessary reporting of these events while maintaining oversight of significant occurrences that could impact radiation safety.
F. Decay-in-Storage
On April 24, 2002, § 35.92, “Decay-in-storage,” was revised to allow medical licensees to dispose of short-lived radioactive waste “without regard to its radioactivity” once they can confirm the waste has become indistinguishable from background. This provides medical licensees with a practical and cost-
IV. Discussion
This discussion section has been divided into multiple sections (Training and Experience, Emerging Medical Technologies, Rubidium-82 Generators, and Other Topics) and subsections to better present information on the major topics impacted by this proposed rule. Each section will discuss what action the NRC is proposing, why the action is being proposed, and who the action affects and how.
The NRC prepared an unofficial redline strikeout version of the proposed changes to regulatory text that is intended to help the reader identify the changes. The NRC is providing the unofficial redline as a reader tool only. Comments on the rule text should be made in this proposed rule.
A. Training and Experience
1. Flexible Physician Training Pathways
The current definition of physician in § 35.2, “Definitions,” means a medical doctor (MD) or doctor of osteopathy (DO) licensed by a State or Territory of the United States, the District of Columbia, or the Commonwealth of Puerto Rico to prescribe drugs in the practice of medicine. The NRC is proposing to change this definition to remove the specific requirement for the individual to be an MD or DO. This change is intended to expand eligibility for foreign-trained physicians whose primary medical qualifications may not be titled MD or DO, but who are fully licensed to practice medicine in the United States, to become AUs. AUs must still meet the training and experience requirements in the applicable subparts of 10 CFR part 35.
In addition, the NRC is proposing to remove from regulations the listing of specific accrediting bodies for residency programs under the training and experience requirements for AU physicians in §§ 35.190. 35.290, 35.390, 35.392, 35.394, 35.396, 35.490, and 35.690. Over time, both residency programs and their accrediting bodies have evolved to incorporate NRC requirements into their curricula. As a result, the NRC no longer finds it necessary to specify accrediting bodies in the regulations. Under this proposed rule, the residency programs would be required to include the proposed classroom and work experience topics to ensure that physicians receive training as part of a structured educational program. This approach allows for greater flexibility by permitting any accredited program, regardless of the accrediting body, to qualify, provided it includes the specified training topics.
2. Physician Residency Pathways
The NRC is proposing to revise its regulations to recognize the structured and comprehensive nature of accredited residency programs in certain medical specialties that inherently include radiation safety training and experience as part of the clinical specialty. Specifically, the NRC proposes to remove the prescriptive requirements in §§ 35.190, 35.290, 35.390, 35.392, 35.394, 35.396, 35.490, and 35.690 for specific numbers of classroom, laboratory, and work experience hours for physicians who have completed residency training in specialties where radiation safety and the clinical use of byproduct material are inherently integrated into the curriculum. This proposed change acknowledges that the depth and scope of training provided in these accredited residency programs are tailored to the clinical application of byproduct materials. The NRC believes that successful completion of such a residency program along with written attestation from a preceptor or residency program director, provides sufficient assurance of an individual's competency to serve as an AU, without the need for fixed hour requirements.
To implement this change, the NRC is proposing to add a residency-based training and work experience pathway for the medical use of unsealed byproduct material in §§ 35.190, 35.290, 35.390, 35.392, 35.394, and 35.396. This new pathway would apply to §§ 35.190 (Training for uptake, dilution, and excretion studies), 35.290 (Training for imaging and localization studies), 35.390, and 35.396 (Training for the parenteral administration of unsealed byproduct material requiring a written directive), where current regulations do not explicitly reference residency training. For §§ 35.490 (Training for use of manual brachytherapy sources) and 35.690 (Training for use of remote afterloader units, teletherapy units, and GSR units), no new pathway would be created as the regulations already require completion of a residency. For all applicable sections, the NRC would remove the prescriptive hour requirements for classroom, laboratory, and work experience for individuals who have completed an accredited residency in specified specialties. This change would not amend the topics that must be covered for classroom and laboratory training and work experience that must be completed in a structured educational program. The topics listed in the regulations are essential to ensuring radiation safety. Individuals completing a residency-based pathway would still need to receive training and experience in all required topic areas during their residency. The written attestation from a preceptor or residency program director should confirm that the individual has completed the required training and experience as required and is able to independently fulfill the radiation safety-related duties as an AU for the medical use the individual is requesting.
The NRC would retain the NRC-approved specialty board pathway and alternate pathway with specified hours for individuals who have not completed residency training in specialties identified in regulations. Finally, the proposed regulations would retain the equivalent qualification pathways where an AU who is qualified for § 35.290 also is qualified for § 35.190, an AU who is qualified for § 35.390 also is qualified for §§ 35.290 and 35.190, and an AU who is qualified for 35.490 also is qualified for § 35.491, “Training for ophthalmic use of strontium-90.”
3. Device and Use Specific Training
Currently, §§ 35.300, 35.392, 35.394, 35.396, and 35.491 require physicians to complete a prescribed number of cases to qualify as an AU. This fixed case requirement does not allow flexibility for physicians who can complete the required work experience and demonstrate the knowledge and competency in radiation safety-related duties through other means than a prescriptive number of cases for the medical use for which they are requesting AU status.
This proposed rule would replace the specified number of cases to qualify as an AU in the NRC's regulations with a requirement that the physician receive sufficient experience in casework during either their residency or the
In addition, §§ 35.300, 35.392, 35.394, and 35.396 currently state that the physician must have experience in administering dosages of radioactive drugs in their respective categories. However, the physical act of administering dosages of radioactive drugs is a practice of medicine and is not always performed by the physician seeking AU status. The purpose of training and experience for AUs is to ensure radiation safety rather than medical competency; this proposed rule revises this requirement to focus on preparing written directives and observing or performing the administration of dosages. While the AUs do not need to physically perform the administration, they must participate in the entire process, gaining experience in all required topics, to ensure they can independently perform all radiation safety-related duties for the medical use for which they are requesting AU status.
In addition, currently, § 35.59, “Recentness of training,” requires individuals to demonstrate related continuing education and experience if their required training and experience was obtained more than 7 years prior to the date of application. However, as the medical use of byproduct material continues to evolve at a quick pace, particularly with the expansion of radiopharmaceutical therapies, experience gained even a few years ago does not ensure that authorized individuals, such as AUs, possess current training or experience in the specific uses for which they are applying. In many cases, the uses for which individuals were originally trained differ significantly from current or emerging practices.
Inadequate training of staff, including AUs, before treating the first patient has been identified as a root cause of a significant number of events, including those described in NRC Information Notice 2024-04, “Recent Medical Events involving Administration of Therapeutic Radiopharmaceuticals.” Similarly, as documented in Information Notice 2019-07, “Methods to Prevent Medical Events,” NRC staff determined that several additional medical events were linked to insufficient training following the introduction of new equipment or software. The ACMUI has also concluded that many medical events involve users who perform treatments infrequently and recommended refresher training for AUs. These findings underscore the need for a performance-based continuing education requirement to ensure that authorized individuals maintain current knowledge and skills as practices and technologies evolve, particularly as the NRC proposes to remove the outdated recentness requirement in § 35.59.
The ACMUI and other stakeholders have recommended that licensees receive additional application-specific training for existing and future EMTs. This includes the potential for future radiopharmaceutical therapies to be licensed under 10 CFR part 35, subpart H. Stakeholders also have expressed concern that the current § 35.59 lacks clarity regarding what constitutes acceptable training and experience to meet the recentness requirement. This has led to uncertainty about what documentation should be submitted with license applications. To address these concerns, the NRC this proposed rule would revise § 35.59 to remove the prescriptive requirement to demonstrate recent training and experience at the time of application and would introduce a performance-based continuing education requirement. This would ensure authorized individuals maintain the necessary education and experience to support radiation safety and regulatory compliance for the uses they are authorized.
Recognizing the differing risk profiles between diagnostic and therapeutic uses, the NRC is proposing a change that would require AUs for diagnostic uses to maintain education or experience in the type of use. For uses requiring a written directive, AUs must maintain education and experience in the specific source, microsource, device, or radioactive drug. This proposed rule also would require instruction on changes to applicable regulations, license conditions, and the licensee's written radiation protection and written directive procedures. This is particularly important because AUs are responsible for supervising others under § 35.27, “Supervision,” and ensuring safe use of byproduct material. As part of this performance-based approach, licensees would no longer be required to submit documentation of recent training and experience with a license application. Instead, a new recordkeeping requirement would be added in a new section, § 35.2059, “Records of continuing education and training,” to ensure that licensees maintain appropriate documentation of continuing education and experience.
The NRC also is proposing to remove the specific work experience requirement for eluting generator systems, measuring and testing the eluate for radionuclidic purity, and processing the eluate with reagent kits to prepare labeled radioactive drugs. Changes in industry practice have resulted in a limited number of generators in use at medical facilities, creating challenges for AU trainees to meet this portion of the experience requirement. The NRC believes that the classroom portion of the requirements for the chemistry of byproduct material could adequately cover the topics previously addressed through hands-on experience. This change would provide the necessary radiation safety information as an alternative to direct work experience.
4. Authorized User Approval for Non-Therapeutic Uses of Unsealed Byproduct Material
The NRC is proposing to amend its regulations to eliminate the requirement for licensees to submit a license amendment before allowing an individual to serve as an AU for medical uses authorized under § 35.100, “Use of unsealed byproduct material for uptake, dilution, and excretion studies for which a written directive is not required,” or § 35.200, “Use of unsealed byproduct material for imaging and localization studies for which a written directive is not required.” Under this proposed rule, licensees would be permitted to approve individuals as AUs for these non-therapeutic uses of unsealed byproduct material without prior NRC review and approval, provided the individual meets the applicable training and experience requirements specified in subpart D. Licensees would be required to maintain documentation of their internal review and approval process, including verification that the individual satisfies the relevant training and experience criteria. This documentation would be subject to NRC inspection.
This proposed change reflects the NRC's risk-informed, performance-based regulatory approach and acknowledges that the medical uses authorized under §§ 35.100 and 35.200, such as diagnostic imaging and localization studies, do not require a written directive and are considered lower-risk activities. By removing the license amendment
5. Training and Experience Categories of Therapeutic Uses of Unsealed Byproduct Material
The NRC is proposing to amend §§ 35.390(b)(1)(ii)(G) and 35.14(a) to remove the prescriptive requirement that individuals seeking AU status must have experience with both low-dose (less than or equal to 1.22 gigabecquerels or 33 millicuries) and high-dose (greater than 1.22 gigabecquerels or 33 millicuries) oral administrations of sodium iodide I-131. Under the current regulation, applicants must document a minimum of three cases in each of these two categories. This rigid structure may not reflect the evolving landscape of radiopharmaceuticals. The proposed change would consolidate these two categories into a single, broader category: oral administration of any radioactive drug for which a written directive is required. This proposed revision eliminates the specific dose-based thresholds for sodium iodide I-131 and instead focuses on the route of administration and the requirement for a written directive. This approach is more risk-informed and performance-based. This proposed change preserves the integrity of the training and experience requirements while allowing for greater flexibility in how those requirements are met. It also would ensure that the regulation remains adaptable to future developments in radiopharmaceuticals that may be administered orally and require a written directive. This proposed amendment would only apply to the categories in § 35.390 for physicians seeking full authorization and does not remove or change the existing work experience requirements for those who desire the limited scope pathway provided in §§ 35.392, “Training for the oral administration of sodium iodide I-131 requiring a written directive in quantities less than or equal to 1.22 gigabecquerels (33 millicuries),” and 35.394, “Training for the oral administration of sodium iodide I-131 requiring a written directive in quantities greater than 1.22 gigabecquerels (33 millicuries).” These limited pathways would remain available for physicians who seek authorization for these specific uses without completing the training and experience requirements for all therapeutic uses of unsealed byproduct material authorized under § 35.390.
The NRC also is proposing to remove unnecessary limitations in the current § 35.390(b)(1)(ii)(G)( 3 ), which requires AU applicants to have work experience with a radionuclide that is primarily used for its electron emission, beta radiation characteristics, alpha radiation characteristics, or photon energy of less than 150 kilo-electron volt (keV). This proposed rule would amend § 35.390(b)(1)(ii)(G)( 2 ) to require parenteral administration of any radioactive drug for which a written directive is required, replacing the removed requirement with a broader, more flexible requirement while still ensuring safety. This proposed change would allow training involving any future radiopharmaceuticals delivered by a parenteral route to be included under this regulation. These revisions provide flexibility for future individuals seeking AU status while ensuring such individuals continue to demonstrate the foundational knowledge and clinical experience necessary to support radiation safety. In conjunction with the proposed changes to § 35.59, these updates also would ensure that individuals maintain current knowledge specific to the uses they are authorized to perform.
6. Authorized User Pathway To Become a Radiation Safety Officer
Under the current regulations, § 35.50(c)(3) allows physicians to be simultaneously approved as both the RSO and AU on a new medical use license or permit, provided they also meet the requirements of § 35.50(d). The NRC is proposing to amend this regulation to allow individuals to seek this pathway on an existing license or permit. There is no safety basis for limiting this pathway solely to new licenses or permits, and this change would provide greater flexibility for an AU to become an RSO on a license at any time without compromising safety.
7. Regulatory Clarification of Training and Experience Regulations
To improve clarity, the NRC is proposing to restructure the training and experience requirements in 10 CFR part 35 by consolidating the specialty board certification approval process into a new section, § 35.58, “Specialty board certification approval.” Currently, the specialty board certification requirements for AUs, RSOs, AMPs, and ANPs are embedded within multiple subparts throughout 10 CFR part 35. When a licensee is reviewing the requirements needed to complete a licensing application for approval as an AU, the requirements of a specialty board certification process is not needed to support the application. Therefore, the NRC is proposing a separation to clarify the training and experience requirements for AUs and to simplify the approval process for specialty boards.
The proposed amendment moves the specialty board approval process from §§ 35.50(a), 35.51(a), 35.55(a), 35.190(a), 35.290(a), 35.390(a), 35.392(a), 35.394(a), 35.490(a), 35.590(a), and 35.690(a) to proposed new § 35.58.
In addition, this proposed rule would clarify that work experience required under each subpart may be obtained under the supervision of an AU at a medical facility authorized to use byproduct materials under that subpart. Under the proposed change, licensees would not be required to verify the training and experience of supervising individuals, as they are already authorized to use the material. This regulatory change would clarify who can supervise required work experience.
B. Emerging Medical Technologies
1. Expansion of Medical Use Generators
The NRC is proposing amendments to 10 CFR part 35 to modernize and expand the regulatory framework for medical use generators. Currently, § 35.204, “Permissible molybdenum-99, strontium-82, and strontium-85 concentrations,” provides specific concentration limits for parent radionuclides for molybdenum-99 (Mo-99)/Tc-99m and Rb-82 generators to limit such exposure, but provides no such limit for Germanium-68/Gallium-68 (Ge-68/Ga-68) generators or flexibility for other new or emerging generators. In addition, generator regulations are contained within subpart D, which are limited to diagnostic uses. As a result of this narrow regulatory framework, generator systems such as the Ge-68/Ga-68 generators have been regulated under § 35.1000. Additionally, the current regulatory requirements for breakthrough testing and effluent limits are prescriptive and located within the diagnostic subpart, which would not be appropriate for future therapeutic applications. As generator technologies become more common and new therapeutic generators are developed, reliance on § 35.1000 would create unnecessary delays in licensing and implementation because each new generator type would need to undergo case-by-case review and approval under
To address these issues, the NRC is proposing to revise and expand the regulatory provisions applicable to medical use generators to accommodate both diagnostic and therapeutic applications and to reduce reliance on § 35.1000 for licensing new generator systems. Specifically, the NRC is proposing to—
a. Revise § 35.2 to add a definition for “breakthrough” to reflect current industry practices and terminology.
b. Move generator breakthrough testing requirements contained in §§ 35.204 and 35.2204, “Records of molybdenum-99, strontium-82, and strontium-85 concentrations,” to new sections §§ 35.93, “Permissible concentrations for generator-produced radionuclides,” and 35.2093, “Records of generator breakthrough testing,” respectively. The proposed new § 35.93 would be located in subpart C (General Technical Requirements) as opposed to subpart D (Unsealed Byproduct Material—Written Directive Not Required) where the current generator breakthrough testing requirements in § 35.204 are contained. This move would support the anticipated licensing of therapeutic generators, which may not fall under the current scope of subpart D. In addition, the proposed § 35.93 would remove prescriptive requirements limited to specific generators and replace them with a more flexible approach that allows licensees to develop and implement written procedures to define acceptable breakthrough limits and testing frequencies that are consistent with generator labeling as set forth in its FDA product approval or nationally recognized standards. To ensure safety and regulatory alignment, the proposed changes would require that the limits and testing frequency be consistent with generator labeling as set forth in its FDA product approval or nationally recognized standards, such as those published by the United States Pharmacopeia (USP). These proposed changes align with the current recommendations outlined in the § 35.1000 licensing guidance for the Ge-68/Ga-68 generators and would ensure that breakthrough testing practices remain current with evolving safety and performance standards and allow flexibility for emerging generators. These proposed changes also would allow licensing of emerging generators without further rulemaking or a separate case-by-case licensing evaluation and guidance development under § 35.1000.
c. Include a requirement in § 35.93(a)(2) that licensees must ensure individuals using generator systems have received operational and safety training specific to the generator model. This codifies expectations that were previously addressed only in guidance ( e.g., EGM-13-003), and expands them to apply to all radionuclide generators, not just rubidium-based generator systems, enhancing regulatory clarity and stability. In addition, § 35.93(b) would require that licensees provide instruction in their generator procedures to individuals involved in generator use, particularly when procedures are first implemented or significantly changed. Because the NRC is proposing to require training on the specific generator model and procedures being used, the NRC is also able to propose the removal of broader training and experience requirements for all physicians seeking authorization under § 35.200 described above. This approach is informed by operational experience, where untrained users used the wrong eluant without understanding the associated risks leading to generator breakthrough events and unnecessary radiation exposure to patients. Ensuring that users are trained on the specific systems they operate mitigates these risks. Overall, this proposed change would represent a significant reduction in regulatory burden, particularly since most physicians do not directly use or supervise generator systems in clinical settings, while still maintaining a high standard of safety in generator operation. Proposed conforming changes also would be made to the associated recordkeeping requirement contained in § 35.2310, “Records of safety instruction,” to add the proposed new § 35.93.
d. Similar to § 35.204, the proposed § 35.93(a)(3) would prohibit the administration of generator eluate to patients or human research subjects if breakthrough measurements exceed the licensee's established limits. Section 35.93(c) would retain the requirement to report any such exceedance at the time of generator elution, but reference new proposed § 35.3093, “Report and notification for an eluate exceeding breakthrough limits,” instead of § 35.3204, “Report and notification for an eluate exceeding permissible molybdenum-99, strontium-82, and strontium-85 concentrations.” Section 35.93(d) would require licensees to retain records of each breakthrough test in accordance with § 35.2093, replacing the previous reference to § 35.2204.
e. Confirming changes would be made to information collections contained in § 35.8, “Information collection requirements: OMB approval,” and recordkeeping requirements would be moved from § 35.2204 to § 35.2093.
These proposed changes are intended to remove the need for licensing emerging generators under § 35.1000 in order to increase licensing efficiency, eliminate unnecessary prescriptiveness, align regulatory requirements with current standards, and ensure that the NRC's regulations remain adaptable to future innovations. By relocating generator requirements out of the diagnostic subpart and into a more general framework, the NRC aims to facilitate broader adoption of generator-based technologies commensurate with the NRC's role in maintaining appropriate oversight and safety assurance.
2. Ophthalmic Applicator Sources and Devices
The NRC is proposing to amend subpart F to replace references to “strontium-90 sources” with “beta-emitting sources,” to reflect the broader range of beta-emitting isotopes that may be used in superficial ophthalmic treatments and remove the outdated assumption that only strontium-90 (Sr-90) is applicable. The proposed revised language would ensure that the regulation remains relevant as new technologies and isotopes are introduced into clinical use, reducing reliance on § 35.1000 licensing, such as what is currently done for the NeoVista Inc's Epi-Rad90 Sr-90 Ophthalmic System and Liberty Vision (LV) Yttrium-90 (Y-90) Disc and iWand®, by allowing these technologies to be licensed under subpart F instead. While § 35.400, “Use of sources for manual brachytherapy,” allows AUs who meet training and experience requirements under § 35.490 to currently use beta-emitting sources for superficial ophthalmic procedures, these proposed amendments would reduce training and experience criteria contained in § 35.491 for superficial ophthalmic procedures for all beta-emitting sources. These amendments aim to modernize regulatory language, support innovation in treatment methods, and align with the NRC's risk-informed, performance-based regulatory framework.
Specifically, the NRC is proposing to amend § 35.491 to modernize and clarify the training and experience requirements for physicians authorized for superficial beta emitter ophthalmic treatments, currently licensed under § 35.1000, and any new innovative superficial ophthalmic treatments. The section title would be amended to read, “Training for superficial ophthalmic use of beta-emitting sources,” and
As the proposed amendment would allow use of a broader range of isotopes instead of just one, the NRC is proposing to introduce device-specific training for the applicable AUs authorized via §§ 35.490 and 35.491. The applicable AUs would be able to satisfy this training either through a vendor-provided program for new users or through supervised instruction by an AU or AMP authorized to use the same device. This aligns with the current recommendations outlined in the § 35.1000 licensing guidance for Liberty Vision, ensuring that AUs are not only trained in radiation safety and clinical application but also are proficient in the specific operational and safety features of the device they will use.
In addition, confirming changes would be made to expand § 35.433, “Strontium-90 sources for ophthalmic treatments,” to allow for any beta-emitting source, not just Sr-90, to be used for ophthalmic treatments. This proposed rule also would make conforming changes to the recordkeeping requirement in § 35.2433, “Records of decay of strontium-90 sources for ophthalmic treatments,” to reflect the broader terminology, requiring licensees to retain records of the activity of each beta-emitting source. This proposed change does not alter the intent or scope of the recordkeeping requirement but instead updates the terminology to reflect current and future clinical practices.
3. Remote Afterloader, Teletherapy, and Gamma Stereotactic Radiosurgery
Subpart H of 10 CFR part 35 establishes requirements for the use of sealed sources in photon-emitting remote afterloader units, teletherapy units, and GSR units. These requirements were originally developed based on the operational characteristics of the devices available at the time. For example, regulations for GSR units were developed in 2002 and calibration and spot check regulations contained in §§ 35.635, “Full calibration measurements on gamma stereotactic radiosurgery units,” and 35.645, “Periodic spot-checks for gamma stereotactic radiosurgery units,” were based on the NRC's review of units and clinical practice used in 1995. In 1995, the units used stationary sources, helmet collimators that needed to be changed manually, trunnions, and head frames drilled into the skull. However, the evolution of medical technology has introduced new units with design and engineering elements that make their operation significantly different than these previous units, resulting in their inability to be licensed under 10 CFR part 35 subpart H. As a result, modern GSR units are currently licensed under § 35.1000.
To support licensing these units under § 35.1000, the NRC developed several licensing guidance documents, including for Akesis Galaxy Rti, Leksell Gamma Knife® Perfexion TM , Leksell Gamma Knife® Icon TM , Elekta Esprit, Xcision® GammaPod TM , and ViewRay TM System for Radiation Therapy. In addition, the NRC expects more EMTs would be licensed under § 35.1000 if subpart H to 10 CFR part 35 is not changed. As licensing under subpart K can increase burden on licensees and regulators and lead to inconsistencies, this proposed rule would eliminate the need to use subpart K for licensing for modern GSR units. In addition, the NRC is proposing additional amendments to support the broader goals of E.O.s 14300 and 14267 to align regulations with current clinical practices and reduce unnecessary requirements that may limit innovation.
To reduce unnecessary regulatory burdens that may hinder innovation, the NRC is proposing to amend:
a. Section 35.2 to include a definition for “gamma stereotactic radiosurgery” and revise the existing definition of “teletherapy.” These changes are part of a broader initiative to modernize and clarify terminology used in 10 CFR part 35, improve consistency in regulatory language, and better reflect current clinical practices and medical community standards;
b. Section 35.610(a)(1) to allow flexibility in securing either the console or its keys, rather than requiring both, while still maintaining the requirement to secure the unit and treatment room when not in use; and
c. Sections 35.615(a) and (b) to remove the prescriptive requirement for a physical door to control access, while preserving the requirement that access to each treatment room entrance must be controlled using an electronic interlock.
These proposed changes preserve the core safety principles of the current regulations while allowing for alternative, modern mechanisms to ensure therapeutic units remain secure and controlled.
As GSR technology advances, the differences between units impacting radiation safety are increasing. With the proposal to allow more unit types to be licensed under subpart H, it is essential that AUs, operators, and calibrators receive training specific to the units they will use. To address this, the NRC is proposing to amend § 35.610(d)(1) to require vendor-provided operational and safety training for all individuals who will operate or calibrate the unit, including the AU, prior to the first use of a new or upgraded unit. Unlike traditional units for which subpart H was originally written, modern units may incorporate various types of immobilization devices, and in the event of an emergency, it is critical that responders are trained to safely release a patient from the specific device in use. Therefore, the NRC is proposing to revise § 35.610(e) to add a requirement to ensure emergency training includes instruction on the specific immobilization devices used with the unit. These amendments would ensure safety is maintained while subpart H is expanded to include different types of units, minimizing the need for future subpart K licensing.
GSR units have advanced along with their safety systems, which help ensure patients are treated accurately and as prescribed. This advancement is detailed in the ACMUI subcommittee report titled “Physical Presence Requirements for the Leksell Gamma Knife® Icon TM .” Currently, § 35.615(f)(3) requires both an AU and an AMP to be physically present throughout the entire GSR treatment. However, due to the enhanced safety features of modern GSR units, the NRC is proposing to reduce this physical presence requirement by amending § 35.615(f)(3), now proposed § 35.615(e)(3):
a. The AU and AMP would still be required to be physically present at the initiation of treatment to ensure proper setup and confirm that the patient receives the intended dose to the correct location.
b. After initiation, the AU may leave the treatment area but must remain immediately available in case of an emergency or treatment interruption that requires a medical decision.
c. Given the high dose rates involved in GSR treatments, the AMP would still be required to remain physically present during the continuation of treatment.
d. The licensee would have the flexibility to designate other appropriate personnel to be physically present to respond to emergencies and remove the patient from the radiation field if necessary.
e. In the event of an unexpected interruption, both the AU and the AMP would be required to evaluate the situation before treatment re-initiation.
This proposed amendment reduces the amount of time the AU must be physically present during GSR
To allow modern and future radiation therapy units, including GSRs, to be licensed under 10 CFR part 35, subpart H, the NRC is proposing to modify or remove prescriptive spot check and full calibration requirements. These proposed changes would eliminate outdated, redundant, or overly prescriptive provisions, better accommodate modern equipment designs, and align with the NRC's risk-informed, performance-based regulatory framework.
Specifically, for GSRs, the NRC is proposing to amend the following full calibration requirements contained within § 35.635:
a. Remove all references to helmet factors in paragraphs (a)(3) and throughout (b). These references are obsolete because newer GSR technologies do not rely on physical helmets or use integrated collimation systems. Removing all references to helmet factors eliminates unnecessary specificity that no longer reflects current practice and equipment design.
b. Revise paragraph (a)(2)(iii) to include collimation components in required post-repair calibrations aligning with the current recommendations outlined in § 35.1000 licensing guidance for modern GSR units. The current language limits the calibration trigger to repairs involving source removal or source assembly components. This proposed rule includes “major repair of component(s) associated with the source assembly or collimation,” ensuring calibrations are conducted when critical components that affect dose distribution are modified. This clarification improves regulatory clarity without increasing burden.
c. Replace outdated and device-specific calibration checks in paragraph (b) with a more performance-based set of criteria. The list includes references to obsolete components ( e.g., helmet microswitches, trunnion centricity) that are no longer applicable to modern units. The proposed revised calibration elements focus on broad system functions such as accuracy of positioning, localization, attenuation, and collimation devices; isocenter coincidence; timer linearity and on-off error; function of system interlocks; and availability of backup power systems. These revisions would provide licensees with greater flexibility in meeting calibration requirements, while aligning with the current recommendations outlined in § 35.1000 licensing guidance for modern GSR units.
d. Add a requirement for full calibration to verify the operability and availability of emergency response equipment required under § 35.610. This change would account for modern and future gamma stereotactic radiosurgery (GSR) units, which incorporate varied emergency response equipment that licensees must ensure is available and operational to respond in the event of an emergency, such as a stuck shutter. Although rare, such events have been reported to the NRC and resulted in sources continuing to be exposed following treatment where licensees have had to use emergency equipment. This requirement would not be expected to increase burden because licensees are already required to have emergency response equipment operational and available to implement emergency procedures specified in § 35.610 and perform full calibration of the unit in accordance with § 35.635.
Next, the NRC is proposing to amend § 35.645 to eliminate redundant and overly prescriptive requirements for periodic spot-checks of GSR units that are already addressed through nationally recognized standards or manufacturer protocols. Specifically, the NRC is proposing to—
a. Remove prescriptive specific spot checks for the GSR units contained in § 35.645(c)(1)-(2) and (d)(1)-(6), such as helmet microswitches, trunnion centricity, emergency timing circuits, and intercom systems. The prescriptive list of outdated requirements for modern GSR units would be replaced with a performance-based approach allowing licensees to follow written procedures established by the AMP and to rely on nationally recognized standards or NRC-accepted manufacturer instructions. NRC-accepted manufacturer instructions would be listed on the NRC's medical use toolkit on the emerging medical technology page after the NRC confirms the instructions to check the necessary systems and components as required per regulation and contain clear tolerance limits for licensee use. This change provides flexibility while maintaining safety and quality assurance.
b. Restructure § 35.645 to clearly define the frequency of required spot checks, aligning with the current recommendations outlined in § 35.1000 licensing guidance for modern GSR units.
c. Revise the current § 35.645(e) into proposed §§ 35.645(d) and (e) to permit the licensee to continue using the unit, provided that any system or device identified as not functioning properly is not used for treatment. The requirement in § 35.645(e) that a licensee must not use a unit if a malfunction is found in a system necessary for treatment would be retained.
d. For remote afterloader units, the NRC is proposing to amend § 35.643 to eliminate redundant and overly prescriptive requirements for periodic spot-checks that are already addressed through nationally recognized protocols or NRC-accepted manufacturer procedures. These changes are intended to streamline regulatory requirements, reduce unnecessary burden on licensees, and align with the NRC's risk-informed, performance-based regulatory framework. Specifically, the NRC is proposing to remove prescriptive specific spot checks for the high dose rate (HDR) units contained in § 35.643(d)(1)-(8), such as electrical interlocks, source exposure indicator lights, viewing and intercom systems, emergency response equipment, and computer clock settings. These requirements would be replaced with a performance-based approach allowing licensees to follow written procedures established by the AMP and to rely on nationally recognized standards or NRC-accepted manufacturer instructions, as described in § 35.643(b). NRC-accepted manufacturer instructions would be listed on the NRC's medical use toolkit on the EMT page after NRC confirms the instructions contain procedures and acceptable tolerance limits for necessary spot checks and calibrations. This shift would align required checks with standards and allow licensees to use innovative or emerging technologies while maintaining safety.
As very few teletherapy units currently exist in the U.S., the NRC is not proposing additional changes to remove prescriptive spot-check or full calibration requirements for these units, as was done for HDR and GSR. However, for consistency with the updates to HDR and GSR regulations, the NRC is proposing to amend spot check requirements contained within §§ 35.632(d) for teletherapy units. This amendment would allow licensees to
4. Establishment of Subpart I for Microsource Brachytherapy
The NRC is proposing to establish a dedicated regulatory framework for microsource brachytherapy by developing a new subpart I under 10 CFR part 35 and making other conforming changes. These changes are intended to incorporate microsources, such as Y-90 microspheres, into traditional medical-use subparts in a way that reflects their unique characteristics. Due to microspheres' unique characteristics, they are currently licensed under § 35.1000. To support licensing these units under subpart K, the NRC developed two licensing guidance documents for 3 types of microspheres, TheraSphere®, SIR-Spheres®, and Eye90®. The use of microspheres for permanent implant manual brachytherapy has grown significantly over the past two decades, and the NRC anticipates continued growth and innovation in this area, including the development of new microsource systems. This proposed rule would eliminate the need to use subpart K for licensing microspheres, while still ensuring proper radiation safety oversight.
The new subpart I of 10 CFR part 35 mirrors the structure of existing subparts F and H but specific requirements would be tailored to the specific operational and safety considerations of microsource brachytherapy based on current licensing conditions contained in § 35.1000 licensing guidance to include microsources. The NRC is proposing to amend § 35.2 to add definitions for “microsource,” “microsource brachytherapy,” and “shunting,” and revise the definition of “prescribed dosage” to include microsources. Adding these definitions is part of a broader effort to modernize and clarify terminology used in 10 CFR part 35 to improve consistency in regulatory language and better reflect current clinical practices and medical community standards.
The NRC is proposing to amend written directive requirements in § 35.40 to include microsource brachytherapy. Specifically, the proposed amendments would—
a. Revise § 35.40(b)(5) to explicitly include “microsource brachytherapy” alongside permanent manual brachytherapy, ensuring that written directives for microsource treatments document the treatment site, radionuclide, and either total source strength or prescribed dosage before administration.
b. Update §§ 35.40(a)(2) and (b)(5) to include microsource brachytherapy with manual brachytherapy to allow changes to the written directive after administration but before the patient leaves the post-treatment recovery area.
c. Modernize terminology to reflect current clinical practice, replacing “permanent implant brachytherapy” with “permanent manual or microsource brachytherapy,” and allowing for documentation of either total source strength, prescribed dosage, or administered activity, which is particularly relevant for microsphere therapies.
Additionally, the proposed subpart I would introduce the following provisions:
a. Section 35.700 would establish the conditions under which microsources may be used, including sourcing from licensed manufacturers or use under an FDA-accepted investigational device exemption (IDE). This provision would ensure that microsources are obtained and used in a manner consistent with existing safety and quality standards.
b. Section 35.710 would outline safety procedures and instruction requirements. Specifically, § 35.710(a) would mandate that microsource administration devices be used in accordance with the Sealed Source and Device Registry, consistent with current licensing guidance. In addition, § 35.710(b) would require licensees to develop, implement, and maintain written procedures for responding to abnormal situations ( e.g., spills, equipment failures, or emergent conditions that could affect the administration of microsources). This is a new requirement that is not currently addressed in the current § 35.1000 microsphere licensing guidance and which is not expected to increase regulatory burden. The addition would be necessary for safety to ensure that applicants have documented procedures to manage abnormal situations that may periodically occur during microsource use, enhancing safety and preparedness and reducing risk. Section 35.710(c) also would require initial operational and safety training for individuals handling microsources, including training provided by the manufacturer or certified trainers, in line with current § 35.1000 licensing guidance. Further, to align with regulations in other subparts for other therapeutic modalities that may involve patients who cannot be released under § 35.75, radiation safety instructions are proposed to be added for personnel caring for such patients or human research subjects in § 35.710(d). These instructions emphasize patient control, contamination prevention, and emergency response. This change is not expected to increase the burden for current yttrium-90 microsphere licensees, as patients are typically released under current clinical practice. However, it is essential to ensure personnel have clear and consistent safety instructions in the event that future microsource administrations require inpatient care. Recordkeeping requirements are proposed to be added for training and procedures to ensure accountability and compliance.
c. Proposed new § 35.790 would define the training and experience requirements for AUs of microsources in line with current § 35.1000 licensing guidance and changes described in Section IV.A., “Training and Experience,” of this document. Specifically, the proposed amendment would require:
i. Completion of a diagnostic and interventional radiology residency, along with classroom and laboratory training in radiation safety fundamentals.
ii. Supervised clinical experience involving at least three microsource cases, including hands-on work with ordering, preparing, administering, and evaluating treatments. Unlike the proposed changes that remove specific case requirements for unsealed byproduct material and superficial ophthalmic use of beta-emitting sources, this proposed rule retains a minimum of three microsource cases currently contained in the § 35.1000 licensing guidance for Y-90 microspheres and is being retained to ensure practitioners have sufficient experience to maintain safety given the continued high number of reported events and the unique delivery systems used for each microsource type.
iii. Written attestation from a qualified preceptor or residency program director confirming the individual's readiness to independently perform radiation safety duties.
Alternatively, prior authorization under § 35.390, 35.396, or 35.490 with supplemental microsource-specific training and attestation would meet the training and experience requirement. The addition of § 35.396 would allow for additional physicians to be licensed based on their prior training and experience under § 35.396, reducing burden from past § 35.1000 licensing guidance recommendations.
a. The regulations in § 35.2310 would establish the recordkeeping requirements for safety instruction provided under §§ 35.93, 35.310,
b. The regulations in § 35.2710 is a proposed new section that would establish the recordkeeping requirements associated with safety procedures and instruction for microsource use. This section would ensure that licensees maintain documentation of written procedures for managing abnormal situations involving microsource administration, aligning microsource recordkeeping requirement for procedures with other modalities contained in 10 CFR part 35 while adding minimal burden. The NRC is proposing these requirements to support accountability and reinforce safe clinical practice in the use of microsource brachytherapy systems.
5. Increasing Flexibility for Safety Precautions Regarding Exposure From Patients
The NRC is proposing to amend its regulations to reduce regulatory burden and increase flexibility for licensees in managing patients or human research subjects who cannot be released under § 35.75. Specifically, the NRC is proposing to combine safety precautions from individual modality subparts into a new section, § 35.76 contained in subpart C, which would be applicable to all uses. By combining the safety precautions, licensees would have flexibility to house individuals who cannot be released under § 35.75 in the same room, regardless of whether they received the same type of administration. This change would allow, for example, a patient who received radiopharmaceutical administration under subpart E to be roomed with a patient who received microsource administration under subpart I, provided the licensee can do so in accordance with 10 CFR part 20 dose limits. This would increase flexibility in patient management and facility use without compromising radiation safety.
The NRC is also proposing to revise the requirement that patients receiving unsealed byproduct material must have a private sanitary facility. This proposed rule would instead require that such patients have access to a sanitary facility used only by individuals who have received similar administrations, without leaving the controlled area. This change would support more efficient facility design and use while maintaining adequate protection against contamination and exposure in uncontrolled areas.
6. Reduce Barriers for Innovative Emerging Medical Technologies
The NRC is proposing amendments to 10 CFR part 35 to reduce regulatory barriers that may delay or discourage the adoption of innovative EMTs. These changes are part of a broader initiative to modernize the medical use regulations and ensure they remain risk-informed, performance-based, and adaptable to technological advancements.
One set of proposed changes addresses the calibration of dose calibrators and survey instruments. Specifically, § 35.60(c) would be amended to permit licensees to submit written calibration procedures for NRC approval in cases where the instrumentation required under paragraph (a) cannot be calibrated using nationally recognized standards or the manufacturer's instructions. This revision would facilitate the use of innovative instrumentation for emerging and novel radioisotopes in medical applications without the need for licensing under subpart K or exemption as current licensees must calibrate these instruments using nationally recognized standards or manufacturer instructions. The NRC would evaluate the submitted procedures to determine whether they achieve calibration tolerances comparable to those established in nationally recognized standards. Conforming changes would be made to §§ 35.12(b)(2) and (c)(2). This approach is intended to support the safe and effective use of new technologies in nuclear medicine while reducing regulatory barriers that may hinder medical research and the development of future clinical applications involving byproduct material.
Similarly, the proposed revision to § 35.61 would reduce the prescriptiveness of survey instrument calibration requirements, allowing licensees greater flexibility to tailor calibration methods to the energy characteristics of new isotopes. Specifically, the proposed amendments would:
a. Revise § 35.61(a)(1) to require calibration of survey instruments for the radiation type and energy range measured, rather than specifying calibration of all scales up to 10 mSv (1000 mrem) per hour. This change would provide licensees with greater flexibility while ensuring that instruments are appropriately calibrated for their intended use.
b. Additionally, the requirement in § 35.61(a)(2) to calibrate two separate readings on each scale or decade would be removed, as it is overly prescriptive and not necessary to ensure accurate instrument performance. The requirement to conspicuously note the date of calibration on the instrument, currently in § 35.61(a)(3), would be retained as § 35.61(a)(2).
The NRC also is proposing to revise § 35.604, “Surveys of patients and human research subjects treated with a remote afterloader unit,” to remove the term “portable” from the description of survey instruments. This change would accommodate the use of innovative detection technologies, provided they meet performance and calibration requirements. The revised language would continue to ensure that radiation sources are properly surveyed and returned to a shielded position before the end of the procedure, while allowing licensees to adopt newer technologies within existing regulatory framework.
Another proposed change clarifies the licensing pathway for manual brachytherapy sources. Under current regulations, subpart F governs the use of sealed sources in manual brachytherapy, but the term “implant” in §§ 35.404(a) and (b), and 35.2404, “Records of surveys after source implant and removal,” has led to confusion regarding whether topically administered sources could be licensed under this subpart. The proposed revisions would clarify that manual brachytherapy sources both topically and inserted within a patient or human research subject are subject to subpart F. This clarification would streamline the licensing process for treatments such as those for skin cancers or post-surgical sites and ensure that licensees can efficiently implement innovative brachytherapy devices without compromising safety.
7. Other Regulatory Clarifications and Implementation Changes for Emerging Medical Technologies
The NRC is proposing amendments to certain regulatory requirements in 10 CFR part 35 to clarify the intent and application of several regulatory provisions related to the medical use of byproduct material. These clarifications are part of the NRC's broader effort to ensure that its regulations remain clear, risk-informed, and aligned with current clinical practices, particularly as new technologies emerge and evolve.
One area of focus is §§ 35.57(b)(4) and 35.1000(c), which address the continued use of medical technologies initially licensed under subpart K. As these technologies become well established and are incorporated into traditional subparts of 10 CFR part 35, the NRC seeks to ensure that licensees and AUs do not need to reapply for approval to continue using them. The proposed changes would establish a clear regulatory pathway to preserve existing authorizations when a § 35.1000 use transitions into a standard subpart use, thereby reducing administrative burden and supporting continuity of care.
The NRC also is proposing to revise § 35.27(a)(1) to replace the phrase “written directive procedures” with “procedures for administrations requiring a written directive.” This change would align the language with § 35.41, “Procedures for administrations requiring a written directive,” and clarify that the regulation applies to the implementation of the written directive, not to the physician's clinical decision-making process. The proposed revision reinforces the NRC's intent to ensure that licensees have procedures in place to verify that the medical use of byproduct material is administered in accordance with the physician's instructions, as documented in the written directive.
Additionally, the NRC is proposing to revise § 35.41(b)(4) to remove prescriptive language that limits the applicability of the requirement for verifying computer-generated dose calculations to specific subparts such as § 35.600 or § 35.1000. This proposed change broadly applies to any modality that uses computer-generated dose calculations, regardless of the subpart under which it is licensed. The proposed revision would ensure that the requirement applies broadly, without inadvertently triggering subpart K licensing for modalities that adopt these technologies in the future.
Together, these proposed changes are intended to clarify regulatory intent, reduce unnecessary burden, support the safe and efficient adoption of EMTs, and ensure that the NRC's medical use regulations remain flexible, forward-looking, and focused on safety outcomes.
C. Rubidium-82 Generators
The proposed revision would include amendments to 10 CFR part 35, subpart A, “General Information,” subpart B, “General Administrative Requirements,” subpart C, “General Technical Requirements,” and subpart D, “Unsealed Byproduct Material—Written Directive Not Required,” to resolve outstanding regulatory issues regarding the use of Rb-82 generators that are currently dispositioned through use of enforcement discretion as described in EGM 13-003. To continue regulating Rb-82 generators without the need for enforcement discretion and without impacting safety, changes would be necessary to allow for the currently accepted methods for calibration of radiation detectors in a dynamic mode and to address dosage measurements for Rb-82 generators. These criteria are currently implemented under EGM 13-003 and remain in effect today. The proposed amendments would codify these requirements into regulation, eliminating the need for ongoing enforcement discretion while maintaining the same safety basis. The NRC is proposing to revise § 35.63 to address longstanding challenges associated with determining the activity of radiopharmaceutical dosages in certain clinical scenarios, particularly those involving short-lived isotopes administered via direct infusion systems, which cannot meet the regulations for measuring patient dosages before administration.
1. Specifically, the title of § 35.63 would be revised from “Determination of dosages of unsealed byproduct material for medical use” to “Determination of dosages for medical use” to reflect the broader applicability of the section. Paragraph (a) to §  35.63 would be amended to exempt incremental administrations that meet the criteria in new paragraph (e) from the requirement to determine and record the activity of each dosage before medical use.
2. Paragraphs (b) and (c), which describe acceptable methods for determining the activity of unit and non-unit dosages, respectively, would be retained but revised to clarify that they do not apply to incremental administrations that meet the criteria in paragraph (e).
3. A new paragraph (d) would be added to allow licensees to determine and record the activity of each incremental dosage administered from a direct infusion system using either a calibrated instrument that is part of the system or a combination of measurement and mathematical calculations.
4. Paragraph (e) would establish specific criteria under which incremental administrations may be performed using direct infusion systems. These criteria include: (1) the administered radioisotope must have a half-life of less than three minutes; (2) a written directive must not be required (for diagnostic use, a written directive would not be required because these administrations involve very short-lived isotopes delivered in small quantities through automated systems, making pre-administration measurement impractical and risk minimal); (3) the radioisotope must be administered directly from the generator or system without additional preparation steps; and (4) the administration must follow the manufacturer's guidelines and procedures. These provisions are designed to accommodate the unique characteristics of isotopes such as Rb-82, which cannot be practically measured before administration using traditional methods due to rapid decay and automated delivery systems.
5. The existing dosage deviation limit in paragraph (d) would be redesignated as paragraph (f) and retained without change, as would the recordkeeping requirement in paragraph (e), which would become paragraph (g). These proposed changes would accommodate the unique characteristics of isotopes such as Rb-82, which cannot be practically measured prior to administration using traditional methods, while maintaining adequate assurance that patients receive the prescribed dosage.
To address direct measurements allowed under the proposed addition of § 35.63(d), § 35.60(d) would be added to require licensees to test the infusion pump flow rate and radiation detectors used by developing, implementing, and maintaining written test procedures. These tests would continue to be required at least every 12 months to ensure continued accuracy and reliability of the infusion systems and associated detectors over time and following any repair that could affect calibration in accordance with EGM 13-003 and the proposed new § 35.60(e). Conforming changes would be made in §§ 35.60(f) and 35.2060, “Records of calibrations of instruments used to measure the activity of unsealed byproduct material,” to ensure licensees retain a copy of procedures used to verify the infusion pump flow rate. These criteria, with the exception of the proposed record keeping requirements for testing procedures under § 35.2060(b), are currently implemented under EGM 13-003 and remain in effect today. The new recordkeeping requirement would ensure traceability and regulatory oversight by documenting not only test results but also the approved methods used to obtain those results, while adding minimal burden. This would close a gap in current rules, align with best practices for quality assurance, and
D. Other Topics
1. Written Directives for Diagnostic Sodium Iodide I-131
The NRC is proposing to amend § 35.40 to remove the requirement that a written directive be prepared for diagnostic administrations of sodium iodide I-131. Currently only diagnostic administrations of sodium iodide I-131 in quantities greater than 1.11 megabecquerels (30 microcuries) require a written directive. This proposed change would reclassify these diagnostic uses under the licensing framework of 10 CFR part 35, subpart D, which governs diagnostic uses of unsealed byproduct material that do not require a written directive. To support this change, §§ 35.100 and 35.200 would be revised to remove the introductory clause referencing § 35.40(b) as a limiting condition. The revision would ensure consistency with the updated written directive requirements in § 35.40.
This revision also would reflect the evolution of clinical practice and radiation safety standards in diagnostic nuclear medicine. In the past decade, only one reported medical event involved a diagnostic administration of sodium iodide I-131 at a dosage level requiring a written directive. This event occurred because the licensee failed to complete the written directive before administration, even though the patient received the correct prescribed dosage. In contrast, there have been three medical events in the same period where patients scheduled for diagnostic administration of sodium iodide I-123 received the wrong radionuclide. Additionally, two older events (both more than 5 years ago) involved patients prescribed doses below the threshold requiring a written directive who instead received higher-than-intended doses of sodium iodide I-131. These examples show that diagnostic administrations of sodium iodide I-131 at dosage levels requiring a written directive have a risk profile comparable to other diagnostic administrations that do not require a written directive. By removing the written directive requirement for these diagnostic administrations, licensees would still be required to report any medical event that occurs, maintaining appropriate safety oversight while eliminating the unnecessary requirement.
2. Reductions in Event Reporting
The NRC is proposing to amend § 35.3045(a) to exclude requiring licensees to report events that result from emergent patient conditions that prevent completion of administration as planned. In addition, the NRC is proposing to add a definition of emergent patient conditions to § 35.2 to clarify that emergent patient conditions are unexpected developments or acute changes in patients' condition, such as vascular spasm or seizure, that occur during the administration which cause a deviation from the planned administration. To ensure the NRC takes appropriate actions to reduce occurrence of significant events, the NRC is also proposing to amend § 35.3045(b) to require reporting of an event under this proposed exclusion if the event is expected to cause unintended permanent functional damage to an organ or physiological system, as determined by a physician. This clarification does not introduce a new reporting category; rather, it aligns emergent patient condition events with existing requirements for events caused by actions of patients, known as patient intervention. This proposed change would be expected to reduce reporting burden by approximately nine events per year while ensuring the NRC is still notified of significant events that could cause unintended significant harm to patients. The proposed changes are intended to reduce unnecessary reporting burden; improve clarity; better align the rule with a risk-informed, performance-based regulatory framework; and continue to ensure significant events that result in unintended permanent functional damage are reported.
In addition, the NRC is proposing to amend § 35.40(a)(2) to allow AUs to revise the written directive during administration for all brachytherapy procedures, except for high dose-rate (HDR) remote afterloader treatments, provided the changes are documented and signed by the AU within 24 hours of the procedure. This change would provide clarity that licensees may use the post-administration portion of the written directive when determining whether a medical event occurred and allows AUs to approve real-time adjustments based on the medical needs of the patient, consistent with their medical judgment. This includes adjusting the written directive if stasis occurs during administration, consistent with the current Y-90 microsphere licensing guidance. However, to ensure leaks or defects in administration device or supplies are reported, the NRC is proposing to add § 35.3045(a)(3) to require reporting if the total dose or dosage delivered differs from the prescribed dose or dosage defined on the written directive before administration by 20 percent, as caused by a leak or defect in administration device or supplies, unless the event resulted from patient intervention or an emergent patient condition. This would ensure the NRC can take appropriate action to prevent reoccurrence of similar events.
Section 35.3047 requires licensees to report any dose to an embryo/fetus that is greater than 50 mSv (5 rem) dose equivalent that is a result of an administration of byproduct material or radiation from byproduct material to a pregnant individual unless the dose to the embryo/fetus was specifically approved, in advance, by the AU. Over the years, this has resulted in licensees reporting events where they made reasonable effort to determine pregnancy status but due to early gestational age or other medical conditions of the patient, they were unable to determine the patient's pregnancy status at the time of administration. Because this is a medical issue and there is no action for the NRC to take in these events, the NRC is proposing to amend the regulation to add § 35.3047(a)(2) to exclude requiring licensees to report these events when they made a reasonable effort to determine pregnancy status, but pregnancy could not be reasonably excluded prior to the administration by the licensee.
The NRC has determined that the proposed revisions to § 35.3045 would maintain adequate protection of public health and safety while improving the utility, clarity, and clinical relevance of medical event reporting. By focusing reporting requirements on events that may indicate a breakdown in safety controls, such as those caused by equipment defects or procedural errors, the rule continues to support the NRC's oversight mission while reducing unnecessary administrative burden on licensees.
3. Expanding Use of Decay-in-Storage
The NRC is proposing to amend § 35.92 to increase the allowable physical half-life for byproduct material eligible for decay-in-storage from 120 days to 275 days. This change would allow licensees to use decay-in-storage for longer-lived materials, such as Lu-177m, which is becoming more prevalent in medical facilities as new lutetium-177 (Lu-177) radiopharmaceuticals receive FDA approval. In addition, this amendment
This proposed amendment would reduce unnecessary disposal costs and regulatory burden for medical licensees while maintaining public health and safety. Under the current rule, licensees must dispose of Lu-177 waste as low-level radioactive waste if it contains Lu-177m, even if the licensee has the space and shielding to safely store the material until it decays to background levels. As medical licensees already maintain secure, shielded storage areas for decay-in-storage, this proposed change would not require new infrastructure or introduce new risks. The proposed change supports the NRC's risk-informed, performance-based regulatory approach by focusing regulatory requirements on materials that pose a greater hazard, while allowing flexibility for low-risk materials.
4. Reduction in License Amendments for Human Subject Research
Under § 35.6(c), licensees currently must seek a license amendment for certain proposed research involving humans even if they are licensed for the type of medical use involved and the research is approved by an institutional review board (IRB). This duplicative requirement has led to delays in research and increased administrative workload for both licensees and the NRC. Therefore, the NRC is proposing to amend § 35.6 to eliminate the requirement for licensees to submit a license amendment before conducting research involving human subjects, provided the licensee is already authorized for the medical use of byproduct material and has obtained IRB approval and informed consent from the research subject. Conforming changes also would be made to § 35.8 as the proposed change would reduce the need for a licensing amendment request. By removing the requirement for an unnecessary license amendment application, the NRC would facilitate timely and efficient research without compromising safety or ethical standards.
5. Reduce Duplication Requirements for Mobile Medical Services
The NRC is proposing to amend regulations specific to mobile medical services contained in § 35.80 to eliminate prescriptive requirements that are redundant to regulations contained in 10 CFR part 20 and other sections of 10 CFR part 35. These changes would ensure regulations for mobile medical licensees are aligned with survey requirements in 10 CFR part 20, and consistent with requirements for transfer of byproduct material for other 10 CFR part 30 licensees. In addition, these proposed changes would reduce unnecessary limitations on licensees and align with the NRC's risk-informed, performance-based regulatory framework.
Specifically, the proposed amendments would remove the following provisions:
a. Section 35.80(a)(2), which requires licensees to check instruments used to measure the activity of byproduct material before use at a client's address. This requirement is overly prescriptive and redundant with § 35.60, which requires that all licensees possess and calibrate instruments used to measure activity of unsealed byproduct material and microsources before administration in accordance with specific requirements. Because § 35.60 provides reasonable assurance that patients receive prescribed dosages for both mobile and non-mobile medical licensees, § 35.80(a)(2) is unnecessary.
b. Section 35.80(a)(3), which requires licensees to check survey instruments for proper operation with a dedicated check source before use at each client's address. This is a standard health physics practice and is already encompassed by the broader requirement in § 20.1501(c) to perform adequate radiation surveys that are necessary to ensure compliance with radiation safety regulations contained in 10 CFR part 20 and are reasonable under the circumstances to evaluate the magnitude and extent of radiation levels, concentrations or quantities of residual radioactivity, and the potential radiological hazards of the radiation levels and residual radioactivity detected. The removal of this provision would eliminate unnecessary regulatory specificity and clarify that there are not different requirements for mobile medical licensees versus non-mobile medical licensees who can also transport survey instruments to different sites.
c. Section 35.80(a)(4), which requires licensees to survey all areas of use to ensure compliance with 10 CFR part 20 before leaving the client's address. Removing this provision would align regulations for mobile medical licensees with regulations for other 10 CFR part 30 licensees who have temporary job sites and would avoid duplicative regulation with § 20.1501 while ensuring radiation safety.
d. Section 35.80(b), which prohibits the delivery of byproduct material to a client unless the client is licensed to receive it. Section 20.1802 requires licensees to control and maintain constant surveillance of licensed material that is in a controlled or unrestricted area and that is not in storage, which would already preclude a mobile medical licensee from delivery of byproduct material to a client unless they would be able to safely secure it or the client has a license. Therefore, retaining this provision in § 35.80 is unnecessary.
Conforming changes are being proposed to remove associated survey records as currently required in § 35.2080(b). The proposed amendments would not introduce new risks or reduce the level of protection for workers, patients, or the public. Rather, they would remove outdated or duplicative requirements and provide licensees with greater flexibility in how they meet existing performance-based requirements, consistent with their capabilities.
6. Expand Temporary Radiation Safety Officer and Changes to Radiation Safety Committee
Section 35.24 outlines the authority and responsibilities for licensees' radiation protection programs, including requirements for RSOs and RSCs. The NRC is proposing to revise § 35.24 to increase the allowable service period for temporary RSOs and to revise the required composition and applicability of RSCs to better reflect current clinical practices. This change would reduce regulatory burden on medical use licensees while maintaining appropriate oversight of radiation safety programs.
First, the NRC proposes to amend § 35.24(c) to extend the allowable duration for a qualified individual to serve as a temporary RSO from 60 days to 120 days per calendar year. Under the current rule, licensees may allow a qualified individual to act as a temporary RSO for up to 60 days without submitting a license amendment. However, the NRC has found that this timeframe is often insufficient for licensees to recruit, hire, and onboard a permanent RSO, particularly in specialized or rural medical settings. Extending the temporary RSO period to 120 days would provide licensees with greater flexibility during staffing transitions or extended absences, reduce the need for license amendments, and support continuity of oversight and safety by avoiding the need to designate multiple RSOs during a transition period.
Second, the NRC proposes to revise § 35.24(f) to clarify that an RSC is only required if a licensee is authorized for
Finally, the NRC proposes to revise the required composition of the RSC by removing the requirement to include a representative of the nursing service. The current rule specifies that the RSC must include an AU for each type of use, the RSO, a representative of management, and a representative of the nursing service. However, in modern medical practice, patients receiving therapeutic byproduct material are often treated on an outpatient basis and are not under the care of nursing staff. As a result, the nursing representative is frequently not involved in the radiation safety aspects of treatment. Removing this requirement would reduce administrative burden on licensees while preserving the core safety oversight functions of the RSC. Licensees may still choose to include a nursing representative or any other clinical staff member on the RSC at their discretion.
These proposed changes are consistent with the NRC's ongoing efforts to modernize its medical use regulations, reduce unnecessary regulatory burden, and align requirements with current clinical practice. The NRC has determined that these proposed amendments would not introduce new risks and would maintain adequate protection of public health and safety for workers, patients, and the public, while providing greater flexibility and clarity.
7. Removal of Redundant Regulations and Addition of Implementation Clauses
As part of the larger response to E.O. 14300, the NRC reviewed 10 CFR part 35 in its entirety to remove redundant regulations. As a result of this review, the NRC is proposing to remove § 35.5 because maintenance of records is already required by § 30.51, which applies to 10 CFR part 35 licensees.
In addition, the NRC reviewed 10 CFR part 35 to remove outdated regulations related to implementation of previous rulemakings. On October 1, 2007, the NRC published a final rule to amend 10 CFR part 35 to implement provisions of the Energy Policy Act of 2005 requiring that the NRC license the medical use of accelerator-produced radioactive material or discrete sources of radium-226 (72 FR 55864). In §§ 35.10(a) and 35.11(c)(1) and (2), the NRC regulations provide waivers for certain entities using this material from requiring a specific license until the entity submitted a medical use license application. As these waivers had end dates of no later than August 8, 2009, for § 35.10(a); December 1, 2008, for § 35.11(c)(1); and August 7, 2009, for § 35.11(c)(2), these paragraphs are outdated and would be removed. In addition, the clause “on or after October 24, 2002,” regarding calibration measurements of brachytherapy sources in § 35.432, is outdated and also would be removed.
V. Specific Requests for Comments
The NRC is seeking advice and recommendations from the public on this proposed rule. The NRC is particularly interested in comments and supporting rationale from the public on the following:
1. The NRC is proposing to revise the definition of “teletherapy” in § 35.2 to clarify that it refers to external beams of ionizing radiation are delivered from an external source without stereotactic guidance. However, the NRC is also considering removing the specific reference to stereotactic guidance or adding additional clarifying language to further expand the definition. As such, the NRC is seeking comments on examples of teletherapy uses and whether the NRC would need to further revise the definition of teletherapy to ensure these teletherapy uses are included. Please provide the basis for your response.
2. As part of this rulemaking package, the NRC has developed guidance to clarify that the physical presence of an AU for the medical use of byproduct is not required under § 35.11(b)(1). 10 CFR 35.11(b)(1) permits licensees to allow individuals who are not AUs to perform certain tasks under the supervision of an AU who is named on the license or permit. As indicated, the NRC has developed guidance to clarify that there is no requirement regarding the location of the AU during the use. The current compatibility category of § 35.11(b) is category C, allowing Agreement States to be more restrictive and potentially require the physical presence of an AU. The NRC has received concerns from industry stakeholders that § 35.11(b) raises transboundary concerns as medical networks have grown and many cross state lines, such that the regulation should be compatibility category B. In addition, the industry stakeholders have expressed concerns that requiring an AU to be physically present or within a specified location of the medical use limits access to treatments in rural areas. As such, the NRC is considering changing this regulation to be compatibility category B. The NRC is requesting specific comments on the appropriate compatibility category for § 35.11(b).
3. The NRC is proposing to establish specific criteria in § 35.63 to allow incremental administrations to be performed using direct infusion systems, including a criterion that calls for the administered radioisotope to have a half-life of less than three minutes. These provisions are designed to accommodate the unique characteristics of isotopes such as Rb-82, which cannot be practically measured using traditional methods due to their rapid decay and automated delivery systems. The NRC is seeking feedback on whether the proposed three-minute timeframe is appropriate or if a higher threshold would be beneficial for a current or expected future medical use and if so, what length half-life would be appropriate (for example, 5 minutes or 10 minutes). Please provide the basis for your response.
4. The NRC is proposing to change § 35.92(a) to allow licensees to hold byproduct material with a physical half-life of less than or equal to 275 days, instead of 120 days, to allow licensees to hold Lu-177m and Co-57 flood sources for decay-in-storage. The NRC is seeking feedback on whether an even longer half-life limit would be beneficial for medical use in this context. Specifically, the NRC is considering increasing the physical half-life beyond 275 days if there is a radioisotope used in medicine that could benefit from such an increase without causing a significant increase in risk. Please comment on whether increasing the half-life limit beyond 275 days would provide a meaningful benefit to medical licensees. If you believe a longer limit would be appropriate, indicate what specific half-life (for example, 300 days or 365 days) you recommend and explain the medical use which would benefit from your recommendation. In addition, describe any safety or operational considerations the NRC should evaluate if the limit is extended further.
5. The NRC is proposing to change the definition of “physician” in § 35.2 to expand eligibility for individuals to become AUs. This change is intended to
6. The NRC is proposing to remove the requirement for a written directive for a diagnostic administration of sodium iodide I-131 in quantities greater than 1.11 megabecquerels (30 microcuries). The requirement was historically established to reduce the potential for unintended thyroid irradiation associated with irreversible thyroid uptake and to help prevent wrong-patient or wrong-procedure administrations. The NRC is seeking feedback on whether eliminating this written directive requirement could raise any safety concerns or otherwise affect patient protection beyond risks associated with diagnostic administrations. In particular, the NRC seeks input on whether current clinical practices of patient identification, procedure verification, and pregnancy screening provide sufficient assurance that diagnostic administration of sodium iodide I-131 are performed safely without the need for a written directive. The NRC is also seeking feedback on whether the removal of this requirement would reduce unnecessary administrative burden on licensees while maintaining adequate protection of patients. Please provide the technical or operational basis for your response, including any relevant experience, data, examples from clinical practices, or information on current institutional practices used to verify patient identity and the intended procedure.
7. The NRC is proposing to remove prescriptive requirements for specific numbers of classroom and laboratory training hours and work experience hours for physicians who have completed residency training in specialties where radiation safety and the clinical use of byproduct material are inherently integrated into the curriculum. This proposed rule identifies diagnostic radiology, nuclear medicine, and radiation oncology as specialties that would not need to complete these prescriptive training hours for training related to uptake, dilution, excretion, imaging, and localization studies. The NRC is seeking feedback on whether these residency programs do and would continue to include sufficient training in these areas, without the prescriptive hour requirements, as the NRC considers whether to remove or maintain the current requirements.
8. In addition, the NRC is proposing to keep the current training hours requirements for physicians who completed fellowship but is considering removing these training hours requirements provided the fellowship curriculum sufficiently integrates radiation safety and the clinical use of byproduct material to ensure the physician can independently fulfill radiation safety-related duties as an AU for medical use. Thus, the NRC is seeking feedback on whether any fellowship curriculum sufficiently integrates radiation safety and the clinical use of byproduct material to ensure the physician can independently fulfill radiation safety-related duties as an AU for medical use, and on any potential considerations of including fellowship training in addition to residency training for meeting the training and experience requirements in subparts D through H of 10 CFR part 35. Please provide the basis for your response.
VI. Regulatory Flexibility

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## Nearby sections

- [91 FR 205 Airworthiness Directives; General Atomics AeroTec Systems GmbH (Type Certificate Previously Held by RUAG Aerospace Services GmbH) Airplanes](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2025-24233.md)
- [91 FR 457 Airworthiness Directives; Gulfstream Aerospace LP Airplanes](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00119.md)
- [91 FR 633 Special Conditions: ZeroAvia, Inc. Model ZA601 Electric Engines](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00171.md)
- [91 FR 937 Air Plan Approval; Ohio; Ohio Permit Rules Revisions](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00258.md)
- [91 FR 1098 National Bank Chartering](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00372.md)
- [91 FR 1104 Airworthiness Directives; The Boeing Company Airplanes](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00409.md)
- [91 FR 1257 Fisheries of the Northeastern United States; Amendment 25 (Revised) to the Northeast Multispecies Fishery Management Plan; Atlantic Cod Stocks in Need of Conservation and Management](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00498.md)
- [91 FR 1464 National Bank Chartering; Correction](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00603.md)
- [91 FR 1471 Corporate Credit Unions](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00595.md)
- [91 FR 1473 Amendment of Class D Airspace and Establishment of Class E Airspace; Fort Worth, TX](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00604.md)
- [91 FR 1477 Marketable Treasury Securities Redemption Operations](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00598.md)
- [91 FR 1494 The Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule III for Model Years 2022 to 2031 Passenger Cars and Light Trucks](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00537.md)
- [91 FR 1724 Removing Redundant, Obsolete, and Inefficient Provisions From the Regulations Governing Restrictions on Lobbying](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00687.md)
- [91 FR 1726 Edith Nourse Rogers STEM Scholarship](https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-00634.md)

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2026-15080. Check the current official text before relying on it. Not legal advice.