Hot lab
The hot lab is where Ac-225 is received, drawn, QC'd, and prepared for administration. The functional requirements build on a standard RLT hot lab, with differences concentrated in contamination-control surfaces and instrumentation — not in overall footprint or shielding mass.
Functional zones inside the hot lab
Surfaces & finishes
Non-porous, seamless work surfaces (stainless or sealed laminate). Avoid joints and crevices where contamination can lodge. Backsplashes and floor coving (typically 4-6 inches up the wall) to facilitate decontamination. Flooring sealed and continuous under benches.
Engineering controls
HEPA-ventilated containment or hood for compounding and any operation with aerosolization potential. Shielded L-block sized for daughter gammas (Bi-213, 440 keV). Negative pressure relative to surrounding spaces where the design supports it.
Instrumentation
Dose calibrator with an Ac-225 setting validated by the AMP. ZnS alpha probe at the survey station for direct frisking. Low-background alpha (or alpha/beta) counter for wipe samples. G-M pancake remains in use for daughter-gamma frisking — not as a replacement for alpha-specific survey.
Storage
Shielded source storage with documented inventory. Separate, clearly labeled storage for incoming doses, in-use material, and waste awaiting decay. Storage capacity sized to the program's peak hold inventory, not its average.
Design decisions to lock in early
Shared vs. dedicated hood
If the hot lab is shared with diagnostic radiopharmaceuticals (Tc-99m, F-18), decide explicitly whether Ac-225 work occurs in the same hood on a dedicated tray, or in a separate hood. Document the decision and the rationale; cross-contamination of a diagnostic workflow with alpha activity is operationally painful to resolve.
Workflow direction
Plan a one-way workflow from receipt → storage → draw → QC → packaging → transport. Reverse traffic across the same bench is the most common source of cross-contamination in retrofitted spaces.
It's worth validating the Ac-225 dial setting on your specific dose calibrator with the AMP and manufacturer — generic settings can be off by clinically meaningful amounts. Documenting the validation matters too; regulators typically ask.
- 10 CFR §35.60 — Possession, use, and calibration of instruments used to measure the activity of unsealed byproduct material.
- NCRP Report No. 155 — Management of Radionuclide Therapy Patients.