Who is responsible for radiation safety in a mobile service — the provider or the client?

The mobile provider, as the license holder, carries primary responsibility for radiation safety, instrument QC, surveys, transport, and records. The client site is responsible for permitting the use through a signed management letter and for the conditions of the space it provides. The signed letter required by 10 CFR 35.80(a) is where these authorities and responsibilities are formally delineated, which is why it is more than a formality.

Should a medical physicist or RSO review a mobile nuclear medicine program?

Yes. A qualified radiation safety officer and medical physicist should establish and periodically audit the instrument QC, survey, transport, recordkeeping, and reciprocity procedures that 10 CFR 35.80 and the license require. Because a mobile service repeats the same compliance steps at many addresses, a well-designed, auditable procedure is what keeps the program defensible across all of them.

Mobile Nuclear Medicine Service: NRC Compliance

Q: What is a mobile nuclear medicine service?

A mobile nuclear medicine service is a licensed provider that brings byproduct material — and often the imaging equipment — to a client's location to perform nuclear medicine studies, rather than the client possessing and using the material itself. The mobile provider holds the radioactive material license and is responsible for radiation safety, while the client site permits the use at its address. In the United States, this arrangement is governed principally by 10 CFR 35.80, 'Provision of mobile medical service' (or the equivalent Agreement State rule).

Q: What does 10 CFR 35.80 require of a mobile medical service?

10 CFR 35.80 requires the mobile provider to obtain a letter signed by the management of each client permitting use of byproduct material at that address and delineating responsibilities; to check instruments that measure activity of unsealed byproduct material (a dose calibrator, at minimum a constancy check) before medical use at each client's address or on each day of use, whichever is more frequent; to check survey instruments for proper operation with a dedicated check source before use at each address; and to survey all areas of use before leaving to confirm compliance with 10 CFR Part 20. Survey records are kept for three years.

Q: How does a mobile service handle transport of radioactive material?

Transport between the base of operations and client sites is regulated by the U.S. Department of Transportation under 49 CFR (primarily Parts 172 and 173), covering package integrity, labeling, marking, placarding where applicable, shipping papers, and driver requirements, in addition to the NRC or Agreement State possession license. Package receipt, surveys, and wipe testing on return also apply.

Q: What happens when a mobile service crosses state lines?

Radioactive material licensing is not automatically portable. When a mobile service operates in an Agreement State other than the one that issued its license, it generally must obtain reciprocal recognition — for NRC licensees entering an Agreement State, or vice versa, this is typically done through NRC Form 241 and the receiving authority's reciprocity process. The service must confirm which authority has jurisdiction at each location before operating there.

A mobile nuclear medicine service delivers byproduct material and imaging to a client's site under the mobile provider's own radioactive material license, and its compliance backbone is 10 CFR 35.80, "Provision of mobile medical service." That single section requires a management letter from each client, instrument checks before use at every address, area surveys before leaving, and defined records — all layered on 10 CFR Part 20 dose limits, U.S. Department of Transportation transport rules, and Agreement State reciprocity when the service crosses jurisdictional lines.¹²³

Because a mobile service repeats the same steps at many locations, the difference between a defensible program and a citation-prone one is a well-designed, auditable procedure applied consistently. This guide lays out the regulatory framework, the technical checks, the transport and reciprocity dimensions, and the recordkeeping that hold a mobile program together.

Introduction

Mobile nuclear medicine lets hospitals and clinics that cannot justify a full in-house program still offer studies such as bone scans, cardiac perfusion imaging, and other Tc-99m-based procedures. A van or shared unit arrives on a scheduled day, the studies are performed, and the material and equipment leave. The clinical convenience is real — but so is the regulatory complexity, because the same radioactive material license obligations that a fixed facility meets once at one address must be met by a mobile service repeatedly, at every client, every day of use.¹⁴

The governing rule in the NRC framework is 10 CFR 35.80, which recognizes mobile medical service as a distinct activity and attaches specific conditions to it. Layered on top are the general medical-use requirements of 10 CFR Part 35, the radiation protection standards of 10 CFR Part 20, DOT transport regulations under 49 CFR, and — critically for services that operate in more than one state — Agreement State reciprocity.¹²³⁵

DRPS supports mobile and fixed nuclear medicine programs across Florida, Maryland, Virginia, Washington DC, California, and Nevada with radioactive material license support and radiation safety officer consulting that turns these requirements into repeatable, auditable procedures.

Topic Explanation

What "mobile medical service" means

In the NRC framework, a mobile medical service is the provision of medical use of byproduct material at a client's address by a licensee based elsewhere. The mobile provider holds the license; the client permits use at its site. This division of roles is the heart of the arrangement and the reason 10 CFR 35.80 exists: it ensures that even though the material moves, a single licensee remains accountable for its safe use at each location.¹

Two structures are common. In one, the provider brings both the radiopharmaceuticals and the gamma camera (often in a coach or trailer). In another, the provider brings the material and staff to use a camera the client already owns. Either way, the license, the radiation safety officer's authority, and the 10 CFR 35.80 obligations travel with the provider.

The core obligations of 10 CFR 35.80

10 CFR 35.80 imposes a specific, checkable set of duties on the mobile provider. In summary, the licensee must:¹

Obtain a client management letter. Before providing service, obtain a letter signed by the management of each client that permits the use of byproduct material at the client's address and clearly delineates the authority and responsibility of the licensee and the client.
Check activity-measuring instruments. Check instruments used to measure the activity of unsealed byproduct material (the dose calibrator) for proper function before medical use at each client's address or on each day of use, whichever is more frequent — with, at minimum, a constancy check.
Check survey instruments. Check each survey instrument for proper operation with a dedicated check source before use at each client's address.
Survey before leaving. Before leaving a client's address, survey all areas of use to ensure compliance with the requirements of 10 CFR Part 20.
Keep records. Retain the record of each area survey for three years, including the date, the results, the instrument used, and the name of the individual who performed the survey.

These are not aspirational; they are inspection items. A mobile provider that cannot produce the client letters and the survey records for its sites has a compliance gap regardless of how safely it actually operated.

For the general medical-use requirements that surround these mobile-specific duties, and for how licenses are structured, see our overview of radioactive material license support and the role of the radiation safety officer.

Key Technical Principles

The dose calibrator constancy check

Before medical use at each client's address (or each day of use), the mobile provider must confirm the dose calibrator reads correctly — at minimum a constancy check using a long-lived reference source such as Cs-137 or Co-57.¹ Constancy asks a simple question: does the instrument give the same, decay-corrected reading it gave when it was last verified?

The expected activity of the reference source decays predictably:

A (t) = A_{0} e^{- λ t}, λ = \frac{ln 2}{T _{1/2}}

For a Cs-137 check source ( $T_{1/2} \approx 30.08$ years), the decay constant is:

λ = \frac{ln 2}{30.08 yr} \approx 0.0230 yr^{- 1}

The percent deviation of the measured reading from the decay-corrected expected value is:

% dev = \frac{A _{measured} - A _{expected}}{A _{expected}} \times 100%

Suppose a Cs-137 source assayed at $A_{0} = 7.40 MBq$ exactly 3.00 years ago. The expected reading today is:

A_{expected} = 7.40 \times e^{- 0.0230 \times 3.00} \approx 6.91 MBq

If the calibrator reads 6.60 MBq, the deviation is $(6.60 - 6.91) /6.91 \times 100% \approx - 4.5%$ . Acceptance criteria are commonly applied at within ±10% following NUREG-1556 Volume 9 guidance and manufacturer instructions; the current regulation requires calibration of activity-measuring instruments in accordance with nationally recognized standards or the manufacturer's instructions rather than a single fixed numeric tolerance.⁵⁶ A result outside the facility's action level triggers investigation and, if needed, a full accuracy check or service before clinical use. Our guide to dose calibrator quality control covers the full constancy, accuracy, linearity, and geometry test set.

The survey instrument operability check

A survey meter that fails silently is worse than none, because it gives false assurance. Before use at each address, the mobile provider checks each survey instrument for proper operation with a dedicated check source — confirming battery status, background, and an on-scale response to a known source.¹ This is distinct from the periodic calibration of the meter, which must still be performed on schedule; see survey meter calibration program.

The area survey before leaving

Before leaving each client's address, the provider surveys all areas of use to confirm compliance with 10 CFR Part 20 — checking for removable contamination and elevated ambient dose rates in injection, imaging, waste, and patient areas.¹² This survey is both a safety act and a documentation act: it protects the client's staff and next occupants, and it produces the record that proves the site was left clean.

The compliance map

10 CFR 35.80 requirement	Primary responsibility	Frequency	Record
Client management letter permitting use	Mobile provider + client management	Before service at each new client	Signed letter retained per license
Dose calibrator function (min. constancy)	Mobile provider	Before medical use at each address, or each day of use (whichever more frequent)	Constancy/QC record
Survey instrument operability with check source	Mobile provider	Before use at each address	Operability check record
Area survey of all use areas	Mobile provider	Before leaving each address	Survey record — 3 years
Transport of material to/from site	Mobile provider	Each trip	Shipping papers, package surveys

The requirements and record retention reflect 10 CFR 35.80; the transport row reflects the DOT rules discussed below.¹³

Clinical Impact

A well-run mobile service extends access to nuclear medicine without diluting radiation safety — but only if the compliance steps are treated as clinical prerequisites, not paperwork. Each check protects a real person: the constancy check protects patients from a mis-assayed dosage; the survey-meter operability check protects staff from an undetected spill; the exit survey protects the client's next patients and cleaning staff from residual contamination.¹²

The occupational-exposure picture for mobile staff is generally favorable when procedures are followed. Studies of nuclear medicine staff dose show that whole-body doses remain well within the 10 CFR Part 20 occupational limits, and that extremity (fingertip) doses — which can be several times the ring-badge reading — are the more sensitive quantity for staff who handle and inject unsealed activity.⁷ This is why extremity monitoring and good handling technique matter as much on a mobile service as in a fixed hot lab.

There is also a business-continuity dimension. Because a mobile provider serves many clients, a single systemic procedural gap — a missing client letter template, an uncalibrated meter, an unlogged survey — is replicated across every site until it is caught, often during an inspection. Getting the procedure right once, and auditing it, protects the entire operation.

Practical Optimization Tips

1. Standardize the client letter

Maintain a template management letter that captures the address, the scope of permitted use, and an explicit delineation of licensee and client responsibilities, and obtain it — signed — before the first service date at any new client.¹

2. Build a per-site QC packet

Create a single, repeatable checklist that walks the technologist through the dose calibrator constancy check, the survey-meter operability check, and the exit survey, with fields for date, source, results, instrument, and initials. One packet per site-day makes the records self-documenting.

3. Decay-correct reference sources in advance

Pre-compute the decay-corrected expected reading for each check source so the technologist can compare against a value, not a memory. This makes out-of-tolerance results obvious and defensible.⁶

4. Treat the exit survey as non-negotiable

Never leave a site without the documented area survey. Build it into the close-out routine so it cannot be skipped when the schedule runs late.¹²

5. Manage transport as a regulated activity

Package, label, and ship material per DOT rules, survey packages on receipt and return, and keep shipping papers with the vehicle. See radioactive material transport under DOT and package receipt and wipe testing.

6. Confirm jurisdiction before every new location

Verify which authority licenses radioactive material at each address, and secure reciprocity before operating across state lines. See NRC/Agreement State reciprocity and Form 241.

Common pitfalls to avoid

Missing or generic client letters. The letter must permit use at a specific address and delineate responsibilities.¹
Skipping instrument checks under time pressure. The constancy and operability checks are required before use at each address, not weekly.¹
Undocumented exit surveys. An unrecorded survey is, for inspection purposes, a survey that did not happen.¹
Assuming a license is portable. Operating in another Agreement State without reciprocity is a jurisdictional violation.
Overlooking extremity dose. Fingertip dose can substantially exceed ring-badge readings for staff handling unsealed activity.⁷

Regulatory Considerations

Mobile nuclear medicine compliance is a stack of coordinated authorities, and a mobile program must satisfy all of them at once. The core frameworks are:

10 CFR 35.80 — Provision of mobile medical service, the mobile-specific rule requiring client letters, instrument checks, exit surveys, and records.¹
10 CFR Part 35 — Medical Use of Byproduct Material, the general medical-use license framework, including authorized users, the RSO, dosage determination, and written directives where applicable.⁵
10 CFR Part 20 — Standards for Protection Against Radiation, setting the occupational and public dose limits (for example, the 50 mSv/year occupational total effective dose equivalent limit and the 1 mSv/year public limit) that the exit survey and program controls are designed to meet.²
NUREG-1556, Volume 9, Revision 3 (2019) — the current program-specific licensing guidance for medical use, which addresses mobile service expectations, instrument QC, and records.⁶
49 CFR (DOT), Parts 172 and 173 — hazardous materials transport rules for packaging, marking, labeling, shipping papers, and placarding of radioactive material moved between the base and client sites.³

Agreement States administer their own equivalent programs, and licensing is not automatically portable. Of the states DRPS serves, Florida, Maryland, Virginia, California, and Nevada are NRC Agreement States that license medical use under their own radiation-control rules, while Washington, DC and Delaware are regulated directly by the NRC. A mobile provider operating across these jurisdictions must confirm which authority issues and inspects its license at each location and obtain reciprocal recognition — for NRC licensees, through the NRC Form 241 process — before working outside its home jurisdiction.⁸ Coordinating the license, the RSO program, transport, and reciprocity is exactly the kind of documentation that separates a defensible mobile program from a fragile one; our guides to preparing for an NRC inspection and radiochemical purity QC address adjacent parts of the same program.

Frequently Asked Questions (FAQs)

What is a mobile nuclear medicine service?

It is a licensed provider that brings byproduct material — and often the imaging equipment — to a client's location to perform nuclear medicine studies, rather than the client possessing the material itself. The provider holds the radioactive material license and is responsible for radiation safety; the client permits use at its address. In the NRC framework this is governed by 10 CFR 35.80.¹

What does 10 CFR 35.80 require of a mobile medical service?

A signed management letter from each client permitting use and delineating responsibilities; a check of the dose calibrator (at minimum constancy) before medical use at each address or each day of use; a survey-instrument operability check with a dedicated source before use at each address; an area survey of all use areas before leaving; and retention of survey records for three years.¹

Who is responsible for radiation safety — the provider or the client?

The mobile provider, as license holder, carries primary responsibility for QC, surveys, transport, and records. The client permits the use through the signed management letter and is responsible for the space it provides. The 10 CFR 35.80(a) letter is where these authorities are formally delineated.¹

How does a mobile service handle transport of radioactive material?

Transport is regulated by the DOT under 49 CFR (chiefly Parts 172 and 173), covering package integrity, labeling, marking, placarding where applicable, shipping papers, and driver requirements, in addition to the NRC or Agreement State possession license. Package surveys and wipe testing on return also apply.³

What happens when a mobile service crosses state lines?

Licensing is not automatically portable. Operating in an Agreement State other than the one that issued the license generally requires reciprocal recognition — for NRC licensees this typically involves NRC Form 241 and the receiving authority's reciprocity process. Confirm jurisdiction before operating at any new location.

Should a medical physicist or RSO review a mobile program?

Yes. A qualified RSO and medical physicist should establish and audit the instrument QC, survey, transport, recordkeeping, and reciprocity procedures the rule and license require, because a mobile service repeats the same steps at many addresses.

Key Takeaways

10 CFR 35.80 is the backbone. Client letters, instrument checks, exit surveys, and three-year survey records are the mobile-specific, inspectable duties.¹
The provider owns radiation safety. The license, RSO authority, and obligations travel with the mobile provider; the client permits use at its address.¹
Checks are per-address, not periodic. The dose calibrator constancy check and survey-meter operability check are required before use at each client's address.¹
Transport is separately regulated. DOT 49 CFR governs packaging, labeling, and shipping between base and client sites.³
Licensing is not portable. Confirm jurisdiction and obtain reciprocity before crossing state lines.
Procedure quality scales. A well-designed, auditable procedure protects every site at once; a systemic gap repeats at every site until caught.⁶⁷

Conclusion

Mobile nuclear medicine service expands access to imaging, but it multiplies compliance obligations across many addresses. 10 CFR 35.80 distills those obligations into a small, checkable set — a client letter, instrument checks, an exit survey, and records — that must be executed the same way, every day, at every site. Around that core sit Part 20 dose limits, DOT transport rules, and Agreement State reciprocity. A mobile provider that builds these into a standardized, auditable procedure, overseen by a qualified RSO and supported by a medical physicist, will protect patients and staff and stand up to inspection wherever it operates. The material moves; the accountability does not.

How DRPS Can Help

Diagnostic Radiation Physics Services helps mobile and fixed nuclear medicine providers translate 10 CFR 35.80 and the surrounding rules into practical, documented workflows. This includes radioactive material license support and amendments, radiation safety officer program design, instrument QC and survey procedure development, transport and reciprocity guidance, and inspection preparation, delivered by board-certified medical physicists through our PET/CT and nuclear medicine physics service.

DRPS supports facilities across our service locations, including Florida, Maryland, Virginia, Washington DC, California, Nevada, New York, Pennsylvania, New Jersey, and Delaware.

A mobile program earns its efficiency only if the safe process is also the standard process — at every address, every day.

Related Resources

References

U.S. Nuclear Regulatory Commission. 10 CFR 35.80: Provision of Mobile Medical Service. ecfr.gov
U.S. Nuclear Regulatory Commission. 10 CFR Part 20: Standards for Protection Against Radiation. ecfr.gov
U.S. Department of Transportation. 49 CFR Parts 172 and 173: Hazardous Materials Regulations (Radioactive Materials). ecfr.gov
U.S. Nuclear Regulatory Commission. 10 CFR Part 35: Medical Use of Byproduct Material. nrc.gov
U.S. Nuclear Regulatory Commission. 10 CFR 35.60: Possession, Use, and Calibration of Instruments Used to Measure the Activity of Unsealed Byproduct Material. ecfr.gov
U.S. Nuclear Regulatory Commission. NUREG-1556, Volume 9, Revision 3: Consolidated Guidance About Materials Licenses — Program-Specific Guidance About Medical Use Licenses. 2019. nrc.gov
Adliene D, Griciene B, Skovorodko K, Laurikaitiene J, Puiso J. Occupational radiation exposure of health professionals and cancer risk assessment for Lithuanian nuclear medicine workers. Environ Res. 2020;183:109144. doi:10.1016/j.envres.2020.109144. doi.org
U.S. Nuclear Regulatory Commission. NRC Form 241: Report of Proposed Activities in Non-Agreement States, Areas of Exclusive Federal Jurisdiction, or Offshore Waters, and Reciprocity. nrc.gov