Abstract: A lighting system includes a plurality of lighting devices and a control device. The plurality of lighting devices are installed in a facility. The control device controls the plurality of lighting devices. The control device controls lighting light projected by at least one lighting device, belonging to the plurality of lighting devices, into colored lighting light, of which a color is different from a color white, to give, upon acquiring information about an event in question, a sign depending on the event in question.

Abstract: Emission computed tomograph wherein a pluralty of detectors surround an object to be examined so as to detect X- or gamma radiation emitted by said object. In front of each of said detectors there is provided a collimator which comprises a pair of main plates and a subsidiary plate interposed therebetween. The plates are made of a material capable of blocking penetration of the radiation therethrough and so supported as to be swingable over an angle sufficient to cover the whole of said object. The plates of all the collimators are simultaneously swung to the same side and at the same angular speed thereby to change the direction of incidence of said radiation on each of said detectors.

Abstract: An emission computed tomograph provided with different types of collimators for selective use with different kinds of radionuclides. The different collimators are alternatively brought into operative position in front of the radiation detector in accordance with the kind of radionuclide being used.