🏠 I-131 Post-Therapy Contact / Release Time (Rough)
UseTeaching contact-restriction magnitude. Written institutional/RSO/national instructions always override.
SourceNRC / SNMMI patient-release guidance concepts (activity/dose-rate criteria; jurisdiction-specific)
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
Paste the link in Slack, Teams, X, or LinkedIn — the preview image comes from this page’s Open Graph card.
Methodology · worked example, guidelines & full notes
Not a release tool.
When to use
Teaching contact-restriction magnitude. Written institutional/RSO/national instructions always override.
How it works
t = ln(A0/A_thr)/(ln2/T½); default physical T½=8.02 d; optional Teff.
Key points
- Not a release tool.
- Thresholds are jurisdiction-specific.
- Physical T½ is conservative.
References
- NRC / SNMMI patient-release guidance concepts (activity/dose-rate criteria; jurisdiction-specific)
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Administered/residual activity | 100 |
|---|---|
| Unit | mCi |
| Activity threshold | 30 mCi |
| Effective half-life Teff (optional) | 2.5 d |
| Dose-rate limit (optional) | 50 µSv/h |
→Rough estimate (physical T½)13.93 d
- Activity：100 mCi / 3700 MBq
- Threshold：30 mCi (1110 MBq)
- Days to threshold (physical T½)：13.93 d
| Administered/residual activity | 100 |
|---|---|
| Unit | mCi |
| Activity threshold | 33 mCi (1.22 GBq · US outpatient historical) |
| Effective half-life Teff (optional) | 2.5 d |
| Dose-rate limit (optional) | 50 µSv/h |
→Rough estimate (physical T½)12.83 d
- Activity：100 mCi / 3700 MBq
- Threshold：33 mCi (1221 MBq)
- Days to threshold (physical T½)：12.83 d
Verification & sources · governance
FAQ
Frequently asked questions
- What are the limits and cautions when using I-131 Post-Therapy Contact / Release Time (Rough)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- Does I-131 Post-Therapy Contact / Release Time (Rough) upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is I-131 Post-Therapy Contact / Release Time (Rough) calculated in practice? Can you show a worked example?
- Inputs: Administered/residual activity 100, Unit mCi, Activity threshold 30 mCi, Effective half-life Teff (optional) 2.5 d, Dose-rate limit (optional) 50 µSv/h → Result: Rough estimate (physical T½) 13.93 d（Activity: 100 mCi / 3700 MBq, Threshold: 30 mCi (1110 MBq), Days to threshold (physical T½): 13.93 d） Inputs: Administered/residual activity 100, Unit mCi, Activity threshold 33 mCi (1.22 GBq · US outpatient historical), Effective half-life Teff (optional) 2.5 d, Dose-rate limit (optional) 50 µSv/h → Result: Rough estimate (physical T½) 12.83 d（Activity: 100 mCi / 3700 MBq, Threshold: 33 mCi (1221 MBq), Days to threshold (physical T½): 12.83 d）