Isotopes of bromine

[4][5] Radiobromine has the advantage that organobromides are more stable than analogous organoiodides, and that it is not uptaken by the thyroid like iodine.

[13] This isotope undergoes β+ decay rather than electron capture about 76% of the time,[6] so it was used for diagnosis and positron emission tomography (PET) in the 1980s.

[4] However, its decay product, selenium-75, produces secondary radioactivity with a longer half-life of 120.4 days.

[15] However, except for longer-term tracing,[6] this is no longer considered practical due to the difficult collimator requirements and the proximity of the 521 keV line to the 511 keV annihilation radiation related to the β+ decay.

[15] The Auger electrons emitted during decay are nevertheless well-suited for radiotherapy, and 77Br can possibly be paired with the imaging-suited 76Br (produced as an impurity in common synthesis routes) for this application.