Patient release and post-administration instructions
Patient release after Ac-225 administration is governed by 10 CFR §35.75, the same framework used for other radionuclide therapies: release is permitted when the total effective dose equivalent (TEDE) to any other individual from exposure to the released patient is unlikely to exceed 5 mSv (500 mrem). The framework is the same; the dose-rate inputs and instruction set are alpha-specific.
Three decisions at release
Dose-rate measurement
Measure dose rate at 1 m (and document the geometry) before release. For Ac-225, the measured dose rate reflects the daughter-chain gamma — primarily Bi-213's 440 keV — not the parent alpha. Use this measurement as the input to the §35.75 calculation, not a generic factor.
Living situation assessment
AU assesses the patient's home situation: presence of children, pregnant household members, shared sleeping arrangements, caregivers. The release decision and any restrictions must account for the most-exposed plausible household contact, not the average.
Written instructions
Per §35.75(b), if release would result in TEDE >1 mSv to any other individual, the licensee must provide written instructions on how to maintain doses ALARA. Most Ac-225 patients should receive written instructions by default.
Patient-facing instructions (typical scope)
Personal hygiene & toileting
Flush twice after toileting; wash hands thoroughly; sit to urinate for the duration specified by the AU. Excretion is the dominant route by which the patient releases activity into the household environment in the first days post-administration.
Household contact
Time-and-distance guidance for sleeping arrangements, close contact with children and pregnant individuals, and use of shared bathrooms. Specific durations are dose-rate-driven and set by the AU; pre-printed instructions should leave the day count blank for the AU to complete.
Special-situation guidance
Hospitalized or institutionalized patients
If the patient cannot meet release criteria, the licensee must follow §35.315 (release-criteria patient confinement) for room placement, posting, dose-rate monitoring, and visitor controls. Plan inpatient capability before scheduling; do not discover it on the day of administration.
Caregivers and family
Caregivers may receive doses above public limits if they have been informed of the risks and have consented. Document the conversation per institutional policy; the AU should lead, not delegate, this discussion.
Travel and re-entry
Patients should be given a wallet card with isotope, date of administration, treating facility, and 24-hour contact — useful for radiation portal monitors at airports, courthouses, and border crossings, which can detect residual activity for days to weeks.
Pre-printing the patient instruction sheet with the isotope name, AU/RSO contact lines, and standard hygiene guidance — while leaving duration fields blank for the AU to fill in from the day-of dose-rate measurement — can help. Static sheets with hard-coded day counts tend to drive inconsistent release practice across a multi-AU program.
- 10 CFR §35.75 — Release of individuals containing unsealed byproduct material or implants containing byproduct material.
- 10 CFR §35.315 — Safety precautions for patients confined for medical reasons.
- NRC Regulatory Guide 8.39 — Release of Patients Administered Radioactive Material.