How do we track the capsule through the GI tract?

We use scintigraphic imaging to track the Enterion^TM capsule. A small amount of indium-111 (¹¹¹In) is sealed in the capsule, and the capsule is dosed to a volunteer with a water drink that contains technetium-99m (^99mTc). The ^99mTc radiolabelled water is used to provide an outline of the GI tract, and the ¹¹¹In radiolabel allows us to superimpose the Enterion capsule to precisely map its location.