Knowledge Hub · Stack Monitor
AERB facility licence renewal at a PET cyclotron facility centres on the annual stack-release summary. The continuous-monitoring trace is the source data — peak release rate, total annual release, isotope breakdown. This page walks the regulatory basis, the detector physics, and the baseline-vs-spectroscopic decision.
Why this matters
AERB licence condition
AERB licensing for a cyclotron and PET-production facility requires continuous monitoring of gaseous effluents released through the building exhaust. The stack monitor sits in the duct (or adjacent, with a collimator) and produces the continuous activity-vs-time trace that becomes the annual stack-release dossier. No equivalent monitor at the stack means no AERB licence renewal — the inspection is not "did anything escape" but "show me the record".
Based on: AERB Safety Code for Medical Cyclotron Facilities.
Read source ↗511 keV detection
Positron-emitter facilities release activity that decays through 511 keV annihilation photons. A NaI(Tl) scintillator sits at the right efficiency-vs-cost point — sensitive enough to read trace activity above building background, cost-effective enough for continuous unattended deployment. Higher-resolution detectors (HPGe) are overkill for the stack-release use case; lower-cost plastic scintillators don't have the 511 keV efficiency.
Based on: IAEA Safety Reports Series 38 — Determination and Use of Scaling Factors for Waste Characterization.
Read source ↗In-duct vs adjacent-duct
Cyclotron building duct paths are not always service-accessible. The stack monitor supports either in-duct installation (detector inside the duct for maximum sensitivity) or adjacent-duct installation (detector beside the duct, with a collimator to shape the field of view) for sites where in-duct mounting is impractical. The same instrument serves both deployments — site flexibility without a separate product.
Based on: Manufacturer product page — installation options.
Read source ↗Baseline vs spectroscopic
The baseline variant (DIM-09, 1K-channel MCA with ROI analysis) is sufficient when the stack release is mono-isotope or near-mono-isotope — a typical F-18-only production facility. The spectroscopic variant (DIM-15 MCA, 1K / 2K / 4K / 8K channels with built-in peak analysis) identifies which isotope is in the release stream from the spectrum itself — useful for multi-tracer cyclotrons (F-18 + Ga-68 + C-11) or for incident-investigation purposes where the question is "what was released".
Based on: Manufacturer product page — variant comparison.
Read source ↗Production-cycle correlation
A cyclotron production cycle has a characteristic stack-release signature — F-18 production typically peaks at end of run and decays through the morning. Correlating the stack-monitor trace against the production-day log verifies that releases match expected production yields. A pattern mismatch (release without a recorded run, or a release magnitude inconsistent with the production yield) is the first indication of a process anomaly.
Based on: AERB Safety Code for Medical Cyclotron Facilities — release recording.
Read source ↗Annual licence-renewal dossier
AERB facility licence renewal requires the annual stack-release summary — total activity released, peak-release rate, isotope breakdown, comparison against the licensed authorised limit. The stack monitor + RMS archive provides the data; the radiation-safety officer summarises the dossier from continuous data rather than from operator estimation. The dossier becomes a data-export task, not a reactive-recordkeeping task.
Based on: AERB Atomic Energy (Radiation Protection) Rules 2004; AERB facility-licence renewal framework.
Read source ↗AERB and IAEA documents that frame stack-release monitoring at positron-emitter facilities.
Indian framework for cyclotron facility licensing, including stack-release monitoring requirements.
Indian regulatory framework for radiation protection, facility licensing and release recording.
IAEA framing for radionuclide characterisation in releases and waste.
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