How to Obtain Authorized User Status

These FAQs are provided as a resource and are intended for educational and informational purposes only. They do not constitute legal advice. You should consult with legal counsel, as well as your radiation safety staff, to determine compliance with all applicable federal, state, local and institutional laws, rules or regulations. ASTRO assumes no responsibility for the accuracy of the below information.

What is an Authorized User (AU) and why would I need to become one?

An AU is a person that meets regulatory training requirements, as determined by the Nuclear Regulatory Commission (NRC) in 10 CFR 35, Medical Use of Byproduct Material. This includes uses such as unsealed sources (radiopharmaceuticals), manual brachytherapy, remote afterloader brachytherapy, gamma stereotactic radiosurgery units, Gamma Knife, and Y90 microspheres.

If you plan on using any modality that is regulated by the NRC, you must become an AU under each specific section of the regulations. For instance, you can be an AU for manual brachytherapy and radiopharmaceuticals, but not for remote afterloader brachytherapy. However, if in the future you decide that you will be treating patients with a remote afterloader, you will need to become an AU under that specific section of the regulations.

AU Eligibility and the ABR

Why doesn’t my board certification indicate that I am AU Eligible?

In March 2022, the American Board of Radiology (ABR) notified the Nuclear Regulatory Commission (NRC) of their intent to terminate the NRC-recognition of all ABR certification processes after December 31, 2023.

Therefore, as of January 1, 2024, any radiation oncologist who is interested in becoming an Authorized User (AU) under 10 CFR 35, Medical Use of Byproduct Material, must obtain AU status via the “alternate pathway.”

See also:

What is the “alternate pathway?"
“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
I finished my residency in 2024 (or later) and therefore do not have an “AU Eligible” determination, how do I become an AU?
Does the NRC have any further guidance?

What does the ABR decision to no longer confer AU eligibility mean and how do I become an AU?

The ABR decision to no longer confer AU eligibility means that instead of the ABR verifying AU eligibility, radiation oncologists will now need to personally demonstrate compliance and meet eligibility for AU status by following the requirements found in 10 CFR 35, Medical Use of Byproduct Material. Each section has specific training and experience (T&E) requirements that must be met before AU status is granted.

See also:

What is the “alternate pathway?"
“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
I finished my residency in 2024 (or later) and therefore do not have an “AU Eligible” determination, how do I become an AU?
Does the NRC have any further guidance?

What is the “alternate pathway?"

The “alternate pathway” is how radiation oncologists become AUs without using board certification to prove compliance with training and experience (T&E) requirements. Fortunately, the ACGME’s Review Committee for Radiation Oncology has already recommended that all radiation oncology residency programs meet the minimum number of training and experience hours required to meet NRC requirements. Each section of 10 CFR 35, Medical Use of Byproduct Material has specific T&E requirements that must be met before AU status is granted.

See also:

“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
I am within seven years of residency and have an “AU Eligible” designation, how do I become an AU?
I finished my residency in 2024 (or later) and therefore do not have an “AU Eligible” determination, how do I become an AU?
I’ve been board certified for 15 years, but never became an AU, now my practice wants to administer radiopharmaceuticals, what do I need to do?
Does the NRC have any further guidance?

Residents and Residency Programs

I am a resident, what do I need to do to become an AU?

As a resident you must ensure that in addition to maintaining meticulous records, complete with preceptor attestations, your training program fills out both NRC form 313A (AUT) and form 313A (AUS) and provides those completed forms to you upon your graduation. NRC form 313A (AUT) addresses AU T&E requirements for unsealed sources, including oral applications of I-131 and parenteral administrations of therapeutic radiopharmaceuticals. NRC form 313A (AUS) addresses T&E requirements for manual brachytherapy, remote afterloader units, teletherapy and gamma stereotactic radiosurgery unites, and the ophthalmic use of strontium-90. This information must also be accessible to you indefinitely should you need it in the future. Your new employer can use this information to add you to their license.

A second option is available to you: ask your training program to make you an AU under their license. This will be dependent on what type of license the facility has, and the structure of your training program. First, you should discuss this with your program director, who will then discuss your request with your radiation safety officer and your radiation safety committee. This will streamline adding you as an AU to subsequent programs/institutions throughout your career.

I am a residency program director; how can I help my residents become AUs? Is it better to make them an AU before they graduate?

The first step is ensuring that you are maintaining meticulous T&E records, complete with preceptor attestations. Both NRC form 313A (AUT) and form 313A (AUS) should be filled out and provided to trainees upon graduation. Copies of records and completed NRC forms should be kept and made available to former trainees indefinitely should they need them in the future.

A second option is available to you: if your trainees have satisfied the training and experience requirements under 10 CFR 35, you can apply to make your trainees AUs under your facility’s license. This will be dependent on what type of license your facility has and the structure of your training program. You should discuss this option with your radiation safety officer and your radiation safety committee. This option may make it easier and faster for graduates to get on the license at their new place of employment.

There is no “right way” in this situation. Each residency program needs to determine which option is best for them.

Post Residency

I am within seven years of residency and have an “AU Eligible” designation, how do I become an AU?

If you are within seven years of residency, and have an “AU Eligible” designation, you need to speak to your radiation safety officer and your radiation safety committee to be added to your facility’s license. Just having the “AU Eligible” designation does not guarantee that you will become an AU; you must be prepared to share your training and experience records with your radiation safety office/radiation safety committee for your application. If you don't have your records, you will need to contact your training program.

See also:

“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
Does the NRC have any further guidance?

I finished my residency in 2024 (or later) and therefore do not have an “AU Eligible” determination, how do I become an AU?

You will have to contact your residency program to ask them to fill out both NRC form 313A (AUT) and form 313A (AUS), complete with preceptor attestations. Once you have the forms, give them to your radiation safety officer and radiation safety committee, and they can add you to the license.

See also:

“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
Does the NRC have any further guidance?

I’ve been board certified for 15 years, but never became an AU, now my practice wants to administer radiopharmaceuticals, what do I need to do?

Regardless of whether your ABR certification indicates that you are “AU Eligible,” your first step is to contact your regulator, which depending on where you are working could be an agreement state, or the NRC. A list of state and federal radiation safety programs can be found at the bottom of this page. The NRC requires additional training and experience after seven years; however, the requirements are determined on a case-by-case basis.

See also:

“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
Does the NRC have any further guidance?

I am an AU for manual brachytherapy, but now I want to administer radiopharmaceuticals, what do I need to do?

If you are an AU under one section of the regulations, in this case manual brachytherapy (10 CFR 35.400), but want to now administer radiopharmaceuticals (10 CFR 35.300), you will need to apply to become an AU for that section of the regulations.

See also:

“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
I am within seven years of residency and have an “AU Eligible” determination, how do I become an AU?
I finished my residency in 2024 (or later) and therefore do not have an “AU Eligible” determination, how do I become an AU?
I’ve been board certified for 15 years, but never became an AU, now my practice wants to administer radiopharmaceuticals, what do I need to do?
Does the NRC have any further guidance?

I am an AU for radiopharmaceuticals, does this mean I am also an AU for all NRC-regulated modalities

No. If you plan on using any modality that is regulated by the NRC, you must become an AU under each specific section of the regulations. For instance, if you are an AU for manual brachytherapy (10 CFR 35.400) and radiopharmaceuticals (10 CFR 35.300), but not for remote afterloader brachytherapy (10 CFR 35.600), and you decide to treat patients with a remote afterloader (10 CFR 35.600), you will need to become an AU under that specific section of the regulations for remote afterloader.

See also:

“What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?”
I am within seven years of residency and have an “AU Eligible” determination, how do I become an AU?
I finished my residency in 2024 (or later) and therefore do not have an “AU Eligible” determination, how do I become an AU?
I’ve been board certified for 15 years, but never became an AU, now my practice wants to administer radiopharmaceuticals, what do I need to do?
Does the NRC have any further guidance?
I am an AU for manual brachytherapy, but now I want to administer radiopharmaceuticals, what do I need to do?

NRC Regulations and Guidance

What are the different requirements for training and experience for each section of 10 CFR 35, Medical Use of Byproduct Material?

The information in this answer is provided as a resource and is intended for educational and informational purposes only. It does not constitute legal advice. You should consult with legal counsel, as well as your radiation safety staff, to determine compliance with all applicable federal, state, local and institutional laws, rules or regulations. ASTRO assumes no responsibility for the accuracy of the below information.

35.390 Training for use of unsealed byproduct material for which a written directive is required: 700 hours of T&E, including 200 hours of classroom and laboratory training, and 500 hours of work experience. The physician must receive written attestation.

Classroom and laboratory training: Radiation physics and instrumentation; radiation protection; mathematics pertaining to the use and measurement of radioactivity; chemistry of byproduct material for medical use; and radiation biology.
Work experience: Ordering, receiving and unpacking radioactive materials safely and performing the related radiation surveys; Performing quality control procedures on instruments used to determine the activity of dosages, and performing checks for proper operation of survey meters; Calculating, measuring, and safely preparing patient or human research subject dosages; Using administrative controls to prevent a medical event involving the use of unsealed byproduct material; Using procedures to contain spilled byproduct material safely and using proper decontamination procedures; Administering dosages of radioactive drugs to patients or human research subjects from the three categories in this paragraph: Oral administration of less than or equal to 1.22 gigabecquerels (33 millicuries) of sodium iodide I–131, for which a written directive is required; Oral administration of greater than 1.22 gigabecquerels (33 millicuries) of sodium iodide I–131; Parenteral administration of any radioactive drug that contains a radionuclide that is primarily used for its electron emission, beta radiation characteristics, alpha radiation characteristics, or photon energy of less than 150 keV, for which a written directive is required.
Written attestation: Has obtained written attestation that the individual has satisfactorily completed the requirements in 35.390. The attestation must be obtained from either: a preceptor AU who meets the requirements and has experience in administering dosages in the same dosage category(ies); or a residency program director.

35.490 Training for use of manual brachytherapy sources: 700 hours of T&E that includes 200 hours of classroom and laboratory training and 500 hours of work experience, under the supervision of an AU. The physician must receive written attestation.

Classroom and laboratory training: Radiation physics and instrumentation; radiation protection; mathematics pertaining to the use and measurement of radioactivity; and radiation biology.
Work experience: Ordering, receiving and unpacking radioactive materials safely and performing the related radiation surveys; Checking survey meters for proper operation; Preparing, implanting and removing brachytherapy sources; Maintaining running inventories of material on hand; Using administrative controls to prevent a medical event involving the use of byproduct material; Using emergency procedures to control byproduct material; and has completed three years of supervised clinical experience in radiation oncology, under an AU who meets the requirements.
Written attestation: Has obtained written attestation that the individual has satisfactorily completed the requirements in 35.490 and is able to independently fulfill the radiation safety-related duties as an AU of manual brachytherapy sources. The attestation must be obtained from either: a preceptor AU who meets the requirements or a residency program director.

35.690 Training for use of remote afterloader units, teletherapy units, and gamma stereotactic radiosurgery units: 700 hours of T&E that includes 200 hours of classroom and laboratory training and 500 hours of work experience. The physician must receive written attestation.

Classroom and laboratory training: Radiation physics and instrumentation; radiation protection; mathematics pertaining to the use and measurement of radioactivity; and radiation biology.
Work experience: Reviewing full calibration measurements and periodic spot-checks; preparing treatment plans and calculating treatment doses and times; using administrative controls to prevent a medical event involving the use of byproduct material; implementing emergency procedures to be followed in the event of the abnormal operation of the medical unit or console; checking and using survey meters; and selecting the proper dose and how it is to be administered; and has completed three years of supervised clinical experience in radiation therapy, under an authorized user who meets the requirements.
Written attestation: Has obtained written attestation that the individual has satisfactorily completed the requirements in 35.690 and is able to independently fulfill the radiation safety-related duties as an authorized user of each type of therapeutic medical unit. The attestation must be obtained from either: a preceptor AU who meets the requirements or a residency program director.

35.1000 Other medical uses of byproduct material or radiation from byproduct material: Specific T&E requirements are found in the guidance documents associated with the relevant technology. Guidance documents can be found on the NRC website, and include modalities such as GammaKnife and Y90 microspheres, among others. Contact your state radiation protection program (for Agreement States) or the NRC for specific instructions.

Does the NRC have any further guidance?

Yes. The NRC provides extensive guidance in NUREG-1556, Volume 9, Revision 3, Consolidated Guidance About Materials Licenses: Program-Specific Guidance About Medical Use Licenses.

Applicants must have successfully completed the applicable T&E criteria described in 10 CFR 35 within seven years preceding the date of the application.
If the applicant completed training more than seven years preceding the date of the application, they must submit documentation of related continuing education and experience since completing the required training and experience.
1. Acceptable continuing education and experience for physicians include the following:
  1. successful completion of classroom and laboratory review courses that include radiation safety practices relative to the proposed type of authorized medical use (this review may include various types of instruction, including online training, as long as the subject matter relates to radiation safety and safe handling of byproduct material for the uses requested).
  2. practical and laboratory experience with patient procedures using radioactive material for the same use(s) for which the applicant is requesting authorization.
  3. practical and laboratory experience under the supervision of an AU at the same or another licensed facility that is authorized for the same use(s) for which the applicant is requesting authorization.
  4. for therapy devices, experience with the therapy unit and/or comparable linear accelerator experience and completion of an in-service review of operating and emergency procedures relative to the therapy unit to be used by the applicant.
Applicants must use the most current version of the applicable NRC Form 313A. Verify that the most current version is being used by checking the “Expires” date in the right, top-hand corner of the form.
1. Use NRC Form 313A (AUS) for manual brachytherapy sources (10 CFR 35.400), ophthalmic use of strontium-90 (10 CFR 35.400), remote afterloader unit(s) (10 CFR 35.600), teletherapy unit(s) (10 CFR 35.600) and gamma stereotactic radiosurgery unit(s) (10 CFR 35.600).
2. Use NRC Form 313A (AUT) for use of unsealed byproduct material for which a written directive is required (10 CFR 35.300), oral administration of sodium iodide I-131 requiring a written directive in quantities less than or equal to 1.22 gigabecquerels (33 millicuries) (10 CFR 35.300), oral administration of sodium iodide I-131 requiring a written directive in quantities greater than 1.22 gigabecquerels (33 millicuries) (10 CFR 35.300), and parenteral administration of any radioactive drug that contains a radionuclide that is primarily used for its electron emission, beta radiation characteristics, alpha radiation characteristics, or photon energy of less than 150 keV, for which a written directive is required.

Note: The NRC will publish an Interim Staff Guidance for the Implementation of 10 CFR Part 35 Training and Experience Requirements sometime in 2025. We will update these FAQs as necessary at the time of publication.

Do all agreement states accept the NRC 313A forms? If not, what do I need to do?

It is possible that some agreement states will not accept the NRC 313A forms. In this case, you will need to use that state’s forms. Your RSO will know whether the NRC 313A forms are acceptable, or if you will need to fill out the state’s form. For links to state radiation protection programs, and relevant forms (where available) please see “State Regulatory Resources” at the bottom of this page.

See also:

Does the NRC have any further guidance?

Contact Information and Other Resources

Who can I contact at ASTRO if I have more questions?

You can send an email to [email protected] if you have additional questions.

Do you have any other resources?

“How to Become an Authorized User”, Dr. Michael Folkert, MD, PhD, Department of Radiation Oncology, University of Washington School of Medicine.

Beyond the Beam: A Radiation Oncology Curriculum for Radiopharmaceutical Therapy

State Regulatory Resources

New York City

Radioactive Materials Program

Advocacy

How to Obtain Authorized User Status

What is an Authorized User (AU) and why would I need to become one?

AU Eligibility and the ABR

Residents and Residency Programs

Post Residency

NRC Regulations and Guidance

Contact Information and Other Resources

State Regulatory Resources

Radioactive Materials Program

Forms

Agreement State

Radioactive Materials Program

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Not an Agreement State

Radioactive Materials Program

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