Patients undergoing 131I-NaI therapy are counselled on its effects and the restrictions and precautions that accompany the therapy
Special considerations for 131I-NaI
- Patients are radioactive after therapy with 131I-NaI.
- Those who come into contact with the patient are at risk of being exposed to the radioactivity
- With simple precautions, the radiation exposure to others is low (less than 1 mSv)1
- Patients continue to excrete 131I-NaI for at least two days following therapy2.
- The majority of the 131I-NaI leaves through the urine
- Small amounts will also be excreted in saliva, sweat, tears, vaginal secretions, and feces
Restrictions and precautions
- Patients are counselled on restrictions and precautions they must follow in the days following treatment.
- The restrictions associated with 131I-NaI therapy are addressed with patients as part of the education during the consent process
- MRTs review important restrictions and precautions with patients prior to administration
- Patient support materials are helpful to illustrate the concepts being explained and can serve as a reference and reminder when the patient leaves the department2
- MRTs remind patients about the importance of staying well hydrated and voiding frequently
- Following therapy, precautions are exercised to avoid exposing others to radioactivity.
- The recommended duration of precautions, as well as the specifics of the precaution (e.g., distances), vary according to the dose.
- General precautionary measures are similar for all doses
- Differences for high-dose therapy are highlighted in the right-hand column of the table below
Where the institution has more stringent guidelines, those should be followed1-10.
| Low-dose 131I-NaI | High-dose 131I-NaI |
|---|---|
| Less than 1110 MBq | Greater than or equal to 1110 MBq |
| Duration of precautions | Duration of precautions |
| Up to 7 days | 7-10 days* |
| Personal contact | Personal contact (same as low-dose with identified adjustments) |
| Avoiding intimate or prolonged physical contact with others3 | Avoiding intimate or prolonged physical contact with others3 |
| Maintaining a distance of at least 1 meter from others1 | Maintaining a distance of at least 2 meters from others1 |
| Sleeping in a separate room4 | Sleeping in a separate room4 |
| Avoiding situations that put the patient in close contact with others, such as public transport and public events | Having no close contact with others, such as public transport and public events |
| Travelling alone after treatment
If not possible, the greatest distance possible between the patient and others should be maintained, while limiting time spent with others in confined spaces (e.g., car)5 |
Travelling alone after treatment
If not possible, the greatest distance possible between the patient and others should be maintained, while limiting time spent with others in confined spaces (e.g., car)5 |
| Avoiding prolonged contact with pregnant women and children under 18 | Having no contact with pregnant women and children under 18 |
| Washing hands frequently with soap and warm water6 | Washing hands frequently with soap and warm water6 |
| Taking further precautions to ensure others don’t come into contact with their radioactive bodily fluids: – Wearing slippers or socks at all times7 – Avoiding foods that create residual saliva, such as bones, peels or chewing gum, that require disposal | Taking further precautions to ensure others don’t come into contact with their radioactive bodily fluids: – Wearing slippers or socks at all times7 – Avoiding foods that create residual saliva, such as bones, peels or chewing gum, that require disposal |
| Bathroom | Bathroom |
| Using a bathroom reserved for their exclusive use for at least 2 days following treatment (because the majority of radioactivity will be excreted via the urine)8 | Using a bathroom reserved for their exclusive use for at least 2 days following treatment (because the majority of radioactivity will be excreted via the urine)8 |
| Flushing the toilet twice after each use with the toilet lid closed5 | Flushing the toilet twice after each use with the toilet lid closed5 |
| Sitting when using the toilet (both genders)1 | Sitting when using the toilet (both genders)1 |
| Taking extra care to wash hands with soap and warm water after using the bathroom6 | Taking extra care to wash hands with soap and warm water after using the bathroom6 |
| Showering at least once a day – baths should be avoided6 | Showering at least once a day – baths should be avoided6 |
| Cleaning the bathroom thoroughly after the precautionary period has passed, before anyone else uses the room, and items that have come into contact with bodily fluids should be disposed of (e.g., toothbrush)6 | Cleaning the bathroom thoroughly after the precautionary period has passed, before anyone else uses the room, and items that have come into contact with bodily fluids should be disposed of (e.g., toothbrush)6 |
| Pregnancy, breastfeeding and conception | Pregnancy, breastfeeding and conception |
| 131I-NaI may be passed to an infant via the placenta and the breast milk and cause permanent damage to the thyroid9 | 131I-NaI may be passed to an infant via the placenta and the breast milk and cause permanent damage to the thyroid9 |
| Waiting to conceive: both men and women wait 6-12 months before attempting to conceive a child1 | Waiting to conceive: both men and women wait 6-12 months before attempting to conceive a child1 |
| Ceasing breastfeeding 6 weeks prior to treatment: due to excessive dose to the breast tissue1 | Ceasing breastfeeding 6 weeks prior to treatment: due to excessive dose to the breast tissue1 |
| Not resuming breastfeeding after treatment for the current child9 | Not resuming breastfeeding after treatment for the current child9 |
| Patients may safely breastfeed subsequent babies | Patients may safely breastfeed subsequent babies |
- Patients and/or caregivers are informed that they should contact the department in the event of contamination (urine spill, vomiting).
- If the patient expires, the caregiver(s) should contact the department for guidance
Patient compliance with precautions (High-dose 131I-NaI)
- The physician may choose to have the patient admitted to hospital.
- Doses over 1110 MBq (30 mCi) are administered to out-patients only when there is confidence that the patient understands and will comply with the strict radiation safety precaution1,10.
- Specific dose levels for determining out-patient procedures may vary, depending on the values submitted and approved by the CNSC during the licence application process
- MRTs comply with the procedures laid out in their CNSC therapy license conditions10
- If the MRT believes the patient is unwilling or unable to comply, a physician is consulted before the dose is administered
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References
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Department of Nuclear Medicine McMaster University Medical Centre. Hamilton Health Sciences Patient Information. Precautions after Out-patient Radioactive Iodine (I-131) Therapy. Available from: http://www.hamiltonhealthsciences.ca/documents/Patient%20Education/I131RadioactiveIodineTherapyHHS-trh.pdf [Accessed 21 Feb 2013]
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Sisson JC, Freitas J, McDougall IR, et al. Radiation safety in the treatment of patients with thyroid diseases by radioiodine 131I : practice recommendations of the American Thyroid Association. Thyroid 2011;21(4):335-346.
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Society of Nuclear Medicine and Molecular Imaging. Fact sheet: Guidelines for Patients Receiving Radioiodine I-131 Treatment. Available from: http://www.snmmi.org/AboutSNMMI/Content.aspx?ItemNumber=5609. Accessed 24 May 2018.
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Canadian Nuclear Safety Commission. Licence Application Guide, Nuclear Substances and radiation Devices, RD/GD 371 (section E2.4). Government of Canada, CNSC. Nov 2011. Available from: http://www.suretenucleaire.gc.ca/pubs_catalogue/uploads/November-2011-RDGD-371-Licence-Application-Guide-Nuclear-Substances-and-Radiation-Devices_e.pdf. [Accessed 28 May 2018]