The most common alarms in any program are not threats. They are either medical isotopes (a hospital patient discharged after a scan or therapy) or NORM (oilfield pipe scale, granite, fertilizer, tile, ceramics, antique uranium glass, lantern mantles). A confident operator dispatches these in minutes; a confused one creates community fear.
8.2 Objectives
Recognize the signature of common medical isotopes.
Recognize NORM signatures and the contexts they appear in.
Avoid escalating routine events to public-alert level.
Build a clean record so that pattern-of-life data (e.g., recurring NORM at a single facility) is captured.
8.3 Triggers for SOP-3
Hospital discharge area portal alarm
Cargo with placards consistent with NORM (oilfield, mining, fertilizer)
Public area NORM signature (granite plaza, antique shop, ceramics importer)
Repeated alarms at a single recurring location
8.4 The Common Medical Isotopes: What You'll See
Patient context is the strongest clue. The operator should ask the alerting party (officer, hospital staff, citizen): was a recent medical procedure involved? If yes, identification usually takes seconds.
Isotope
Use
Typical persistence
Spectrum hint
Tc-99m
Bone scan, cardiac, sentinel node
Hours
Single peak ~140 keV; common
F-18
PET scan
Hours
Annihilation peak at 511 keV; gone within a day
I-131
Thyroid therapy/diagnosis
Days to weeks
Multiple peaks incl. 364 keV; persistent
I-123
Thyroid imaging
Hours
~159 keV peak
Lu-177
Targeted radionuclide therapy (oncology)
Days
Multiple peaks; 113, 208 keV
Ga-67
Inflammation/infection imaging
Days
Multiple peaks 93, 184, 300, 393 keV
Tl-201
Cardiac perfusion
Days
Lower-energy gammas + characteristic X-rays
Operator workflow for a suspected medical alarm:
Identify with the SAM handheld.
Confirm patient context with the alerting party.
Document: name (with appropriate privacy handling), procedure, time of dose, isotope.
Release if appropriate; advise patient to carry a wallet card if recurring portal alarms are likely (some hospitals provide these).
Log the event for pattern recognition.
8.5 NORM in the Wild
Naturally occurring radioactive materials produce alarm signatures that operators see again and again:
K-40 in fertilizer, salt substitutes, granite, ceramics, certain foods. Single peak at 1460 keV. Always present at low levels.
Th-232 series in thoriated welding rods, lantern mantles, certain ceramics, and granite. Multiple peaks including 583 keV (Tl-208), 911 keV, 2614 keV.
U-238 / Ra-226 series in oilfield pipe scale, phosphate fertilizer, certain ceramics, granite countertops. Many peaks, with 186 keV (U-235 / Ra-226) and 1764 keV (Bi-214) as common landmarks.
A NORM ID is not the end of the conversation. A cargo of NORM should be consistent with the manifest. A fertilizer truck reading thorium does not match, that calls for further inspection. A truck of granite slabs reading uranium daughters absolutely matches. Context and identification work together.
8.6 Differentiation in Practice
A patient scan and a Cs-137 industrial source look nothing alike on a spectrum:
Tc-99m = single peak at 140 keV. Done.
Cs-137 = single peak at 662 keV. Done.
F-18 = single peak at 511 keV. Done.
NORM = a forest of peaks spread across the spectrum, often dominated by K-40 at 1460 keV.
The SAM family's CeBr/LaBr resolution makes these distinctions trivial. Operators who once needed reachback for ambiguous calls now resolve them on scene.
8.7 When to Still Escalate
Even a confident medical or NORM identification deserves escalation in some cases:
Combined NORM + something else. A truck reads uranium daughters AND a discrete Cs-137 peak, the second isotope is the issue.
Patient context that doesn't add up. A "discharged patient" with Cs-137 identification, that's not a patient.
Recurring identification at an unexpected location. A daily I-131 alarm at a non-hospital address, log and investigate.
Anything you can't explain. When in doubt, send it.