An embolization device for occluding a body cavity includes one or more elongated, expansible, hydrophilic embolizing elements non-releasably carried along the length of an elongated filamentous carrier that is preferably made of a very thin, highly flexible filament or microcoil of nickeltitanium alloy. The image capturing device is configured to receive a plurality of images reflected by the plurality of reflective devices. The tubes have a first fluid flowing through them and the vaporous fluid flowing around them. Bristles for the brush are heated to form a small fuse at their ends. The speed reducer is disposed between the rotor and the hub with bearings provided between the speed reducer and the hub. The light receiving device includes a photoelectric conversion element for receiving a light signal and performing photoelectric conversion of the light signal, and a data detection section for using an decision level for the light signal received by the photoelectric conversion element to detect modulation data included in the light signal.