An imaging capsule with a fail-safe radiation mechanism includes a first rotatable disk with a radiation source mounted thereon and having a collimator structure allowing emission of radiation from radiation source from a few locations on the first disk. A second rotatable disk surrounds the first disk, is rotatable relative to first disk, and includes areas that block radiation and areas that are transparent to emission of radiation. In a rest position, second disk is situated relative to first disk such that areas that block radiation are blocking the emission of radiation from the locations on the circumference of the disk that allow the emission of radiation. A motor is activated to rotate one of the disks and allow emission of radiation. A connector is configured to automatically return first disk and second disk to the rest position when the motor is deactivated.