Since boiling water is unreliable in destroying endospores, how should you use heat in medical applications to ensure spore destruction

Endospores are resistant to heat and radiation, but can be destroyed by burning or by autoclaving at a temperature higher than 100 °C.
They are able to survive at 100 °C for hours, although the more time they spent there the fewer that will survive.
Another possible way is to make them reactivate to their vegetative state and then destroy them, because they are easier to kill.