Gallium-67 (67Ga)

Gallium-67 (⁶⁷Ga) is a radioactive isotope of gallium. It is used in the form of intravenous injection of gallium-67 citrate to detect certain lymphomas and carcinomas and some inflammatory lesions.

⁶⁷Ga has a long elimination radioactive half-life of 78 hours: 3.3 days ^{(ACMUI 2019}); the biological half-life of gallium citrate is 48 to 68 hours ^{(Mountford 1989)} and is detected in breast milk for at least 2 weeks. ^{(Rubow 1991, Tobin 1976, Larson 1971)} and in the infant intestine. ^{(Rubow 1991)}

Nuclear medicine centers can measure the radioactivity of milk to determine when breastfeeding can be safely resumed. ^{(Stabin 2000)} 

Following administration of ⁶⁷Ga, a 21 to 28 day breastfeeding interruption is recommended ^{(Mattsson 2021, ACMUI 2019, IAEA 2018 p283, Sachs 2013, ICRP 2008 p164, Mountford 1999)} so that the infant does not receive a radiation dose greater than 1 mSv. ^{(Mattsson 2021)}

Other agencies ^{(US.NCR 2016 pU-10)} propose breastfeeding interruption times depending on the dose administered: 

• 1 month for 150 MBq [4 mCi].
• 2 weeks for 50 MBq [1.3 mCi].
• 1 week for 7 MBq [0.2 mCi].

If, despite this long period, the mother wishes to continue breastfeeding, it is advisable:

• Have milk expressed prior to the test available to administer during the interruption period or feed with a breast milk substitute.
• Express milk regularly during the interruption period, which can be stored frozen and used again after 10 physical half-lives of ⁶⁷Ga, i.e. 33 days, during which time the radioactivity has disappeared. ^(LactMed)

A dose of less than 190 MBq of ⁶⁷Ga administered to the mother does not require avoiding close contact with the baby. ^{(Mountford 1999)}