Таллий-201

Thallium-201 in the form of thallium chloride which is used in myocardial perfusion imaging. It has a maximum radioactive half-life of 43 hours ^{(ARSAC 2024)}, and the terminal elimination half-life of the thallium ion from the body is about 10 days.

Thallium-201 levels in the milk of two mothers who received a dose of 111 MBq would not have resulted in irradiation in excess of the maximum allowable radiation dose, even without any break in breastfeeding time. ^{(Johnston 1996, Murphy 1989).}

The breastfeeding interruption time is calculated so that the dose to the infant is less than 1 mSv in a single administration. The annual infant dose should also be less than 1 mSv and consideration should be given to extending break times if multiple exposures are expected. ^{(ARSAC 2024)}

Note: 1 mCi (millicurie) = 37 Mbq (megabecquerel)

The time for discontinuation of breastfeeding after administration of Thallium-201 depends on the dose admitted to the mother and on the various experts and specialized agencies (For some doses there is no agreement among the different bibliographic sources):

• 80 Mbq dose → 10 hours ^{(ARSAC 2024)}, or no discontinuation required ^{(Mountford 1999).}
• 100 Mbq dose (3 mCi) → 48 hours ^{(Mattsson 2021, ICRP 2008, Johnston 1996)}
• 100 Mbq dose (3 mCi) → 96 hours ^{(ACMUI 2019, IAEA 2018, Stabin 2000)}
• > 110 MBq dose → 2 weeks ^{(US.NCR 2016)}

In case of doubt, milk radioactivity can be measured at a nuclear medicine center until measurements on milk samples demonstrate that it is safe to restart feeding. ^{(ARSAC 2024, Stabin 2000)}

After doses above 150 MBq, consideration should be given to temporarily limiting close contact between mother and infant. ^{(ARSAC 2024)}

During the discontinuation period, milk should be expressed regularly as completely as possible and either discarded or frozen and stored appropriately (ARSAC 2024) This stored milk will be suitable for consumption after 10 T ½ (20 days) when the radioactivity will have completely disappeared. If the mother has expressed and stored milk prior to th^{e test, she may give it to the baby during the period of interrupted breastfeeding.} (ARSAC 2024)

See below the information of this related product:

• Scintigraphy (Unsafe. Moderate/severe adverse effects. Compatible under certain circumstances. Follow-up recommended. Use safer alternative or discontinue breastfeeding from 5 to 7 T ½ . Read Commentary.)