Radioactive iodine isolation period based on administered activity
Radiation safety “restricted time/period” after ^131I therapy is determined by administered activity and target population exposure assumptions, with separate guidance for nighttime (sleeping) and daytime (work/public contact) restrictions. [1]
Isolation periods after radioiodine for hyperthyroidism
Restricted periods shown are 24-hour cycles after administration. [1]
Nighttime restriction: sleeping separation from adults
- 10 mCi: 3 days [1]
- 15 mCi: 6 days [1]
- 20 mCi: 8 days [1]
- 30 mCi: 11 days [1]
Nighttime restriction: sleeping separation from pregnant partners, infants, or children
- 10 mCi: 15 days [1]
- 15 mCi: 18 days [1]
- 20 mCi: 20 days [1]
- 30 mCi: 23 days [1]
Daytime restriction: return to work
- 10 mCi: 1 day [1]
- 15 mCi: 1 day [1]
- 20 mCi: 2 days [1]
- 30 mCi: 5 days [1]
Daytime restriction: avoidance of extended time in public places
- 10 mCi: 1 day [1]
- 15 mCi: 1 day [1]
- 20 mCi: 1 day [1]
- 30 mCi: 3 days [1]
Isolation periods after radioiodine for thyroid carcinoma or remnant ablation
Restricted periods shown are 24-hour cycles after administration. [1]
Nighttime restriction: sleeping separation from adults
- 50 mCi: 1 day [1]
- 100 mCi: 1 day [1]
- 150 mCi: 2 days [1]
- 200 mCi: 4 days [1]
Nighttime restriction: sleeping separation from pregnant partners, infants, or children
- 50 mCi: 6 days [1]
- 100 mCi: 13 days [1]
- 150 mCi: 18 days [1]
- 200 mCi: 21 days [1]
Daytime restriction: return to work
- 50 mCi: 1 day [1]
- 100 mCi: 1 day [1]
- 150 mCi: 1 day [1]
- 200 mCi: 1 day [1]
Daytime restriction: avoidance of extended time in public places
- 50 mCi: 1 day [1]
- 100 mCi: 1 day [1]
- 150 mCi: 1 day [1]
- 200 mCi: 1 day [1]
Setting-based applicability limits
Inpatient treatment is recommended when the proposed ^131I dose is ≥200 mCi or when calculated TEDE to family/caregivers or to higher-sensitivity individuals is expected to exceed prespecified limits. [1]
Dose-advice interpretation constraints
The restricted periods above are examples that should be modified based on patient-specific factors and local radiation safety officer calculations. [1]