Democritus, you say that in medical imaging, you use an isotope with a half-life of six hours… Do you produce it on-site? How?
Meanwhile, the “islands of stability” are only one isotope each. The next one is at 113, and I remember reading reports that it had, in fact, been synthesized (before 112 or 111). The half-life is an astonishingly long dozen seconds or so, which is pretty impressive, considering that most half-lifes up there are in the millisecond range.
Oh, and if you want an element that’s really tough to produce, try replacing the nucleus of an atom of your choice with a microscopic black hole of the same charge. It might even be stable.