Physicist's Notes · Ranger Survey Meter

Four cadence bands, one survey instrument, and the AERB dossier built from data.

A working radiation-safety survey programme runs at four cadence bands — daily, weekly, monthly, annual — with the radiopharmacist owning daily, the physicist owning weekly and monthly, and the RSO owning annual. This post walks each band, the NORM-screening protocol that sits alongside routine surveys, and the six-item AERB inspection dossier the Ranger USB log feeds.

The four cadence bands

What to scan, what passes, what triggers escalation

Band	Trigger	Scan	Pass	Fail action
Daily — radiopharmacist	Before the first dispensing run; end of dispensing shift	Bench surface, dispensing-area floor, dose-calibrator well, waste-area corridor	All locations within ± 2× ambient background	Investigate hot spot; clean if surface; escalate to physicist if persistent
Weekly — physicist	One scheduled slot per week	Full hot-lab + injection-room + waste-store walk-through	No location > 4× background; all readings logged to RMS	Identify source — usually a misplaced vial, glove drop or spill incident
Monthly — physicist	First working day of the month	Wipe tests on all sealed-source storage cabinets + dispensing benches	Removable activity < 0.4 Bq/cm² (typical AERB threshold for sealed sources)	Quarantine the source; clean the surface; document the incident
Annual — RSO	Once per calendar year; before AERB inspection	Calibration check against a NIST-traceable Cs-137 reference + full facility survey log review	Sensitivity within ± 20 % of published 3,340 CPM/mR/hr; calibration certificate renewed	Send for factory calibration; replace if drift exceeds calibration tolerance twice

Source: AERB Safety Code for Nuclear Medicine Facility; AERB Atomic Energy (Radiation Protection) Rules 2004; IAEA Safety Reports Series 40.

NORM screening

The separate protocol that sits alongside routine surveys

NORM screening covers naturally-occurring radioactive materials — Th / U decay products in scrap metal, building materials, mining samples and some industrial scrap.
The Ranger's 10 keV photon threshold catches the U / Th X-ray complex (typically 12–20 keV) and the Bi-214 / Pb-214 progeny line at 295 keV — the two signatures NORM screening looks for.
Screening protocol: pass the detector window across the surface at ≈ 2 cm distance, at a walk-speed slow enough that any spot stays under the window for ≥ 5 seconds.
Alarm threshold: typically set at 3× ambient background. Investigation threshold at 5–10× background depending on site activity.
When a hot spot is found: log the location, dose rate, and take a wipe sample. The wipe goes to gamma spectroscopy (well counter) for isotope identification.

AERB inspection dossier

Six items the Ranger USB log feeds

USB log file for each survey day, exported from Observer software (CSV or PDF), timestamped to the device clock
Annual NIST-traceable Cs-137 calibration certificate, retained for the AERB facility-licence period
Wipe-test result log: location, surface area swabbed, gamma-spec result, removable activity in Bq/cm²
Calibration drift trend: sensitivity reading at each annual calibration, plotted to catch instrument degradation early
Incident log: any survey reading that exceeded the action threshold, including the response taken
AERB inspection-ready package: all six items above bundled per inspection window

Source: AERB Safety Code for Nuclear Medicine Facility — record-keeping section; manufacturer Observer software.